Second Edition
Indoor
Air Quality
The
Latest
Sampling
and
Analytical
Methods
CRC Press
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Contents
Preface.....................................................................................................................xv
Acknowledgments ............................................................................................. xvii
About the Author ................................................................................................ xix
Section I The Starting Line
1. Historic Overview ..........................................................................................3
Evolution of Indoor Air Quality Investigations ..........................................3
Litigation ...........................................................................................................5
Differences in Health Effects .........................................................................6
A Misguided Premise .....................................................................................7
Regulations, Requirements, and Guidelines ...............................................7
U.S. Government Directives ......................................................................8
EPA National Ambient Air Quality Standards ......................................8
OSHA Workplace Standards .....................................................................9
ACGIH Workplace Guidelines ................................................................ 10
ASHRAE Criteria for General Public ..................................................... 10
ACGIH Guidelines Revisited in Older ASHRAE Standard........... 11
International Enforcement and/or Guidelines ................................ 12
ASHRAE Criteria for Residences....................................................... 12
ASHRAE Criteria for High Performance Buildings ....................... 12
Summary......................................................................................................... 13
References ....................................................................................................... 13
2. Investigation Plan......................................................................................... 15
Documents Review........................................................................................ 17
Building a Walk-Through ............................................................................. 18
Occupied Areas ......................................................................................... 18
Air Handling System................................................................................ 19
Bathroom Air Exhaust.............................................................................. 20
Sewer System ............................................................................................. 21
Occupant Activities .................................................................................. 21
Interviews with Facilities Personnel ........................................................... 21
Maintenance Staff .......................................................................................... 21
Custodial Staff ...........................................................................................22
Observation of Surrounding Areas............................................................. 23
Assessing Occupant Complaints................................................................. 23
Questionnaires .......................................................................................... 24
v
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Contents
Types of Questionnaires....................................................................... 24
Questionnaire Response Rate ............................................................ 24
Informational Data............................................................................... 25
Interviews................................................................................................... 27
Summary......................................................................................................... 27
References ....................................................................................................... 27
3. The Hypothesis ............................................................................................. 29
Information Review.......................................................................................30
Building Assessment ................................................................................30
Complaint Occupant................................................................................. 31
Hypothesis Development .............................................................................34
The Proactive Approach ............................................................................... 36
Beyond the Scope........................................................................................... 37
Medical Physicians ................................................................................... 37
Industrial Hygienists and Toxicologists ................................................ 38
Psychiatrists ............................................................................................... 38
Summary......................................................................................................... 39
References ....................................................................................................... 39
Section II Omnipresent Bioaerosols
4. Pollen and Spore Allergens ........................................................................43
Occurrence of Pollen and Spore Allergens ................................................43
General Information .................................................................................44
Spore-Producing Fungi and Bacteria ..................................................... 49
Fungi ........................................................................................................... 49
Molds...................................................................................................... 49
Mushrooms ........................................................................................... 52
Rusts and Smuts ................................................................................... 53
Slime Molds...........................................................................................54
Bacteria ....................................................................................................... 55
Indoor Source Information ...................................................................... 55
Sampling Strategy.......................................................................................... 56
Sampling and Analytical Methodologies.................................................... 57
Slit-to-Cover-Slip Sample Cassettes ....................................................... 57
Slit-to-Slide Samplers..................................................................................... 58
Analytical Methods .................................................................................. 59
Commercial Laboratories......................................................................... 59
Helpful Hints............................................................................................. 59
Interpretation of Results ............................................................................... 60
Summary......................................................................................................... 66
References ....................................................................................................... 66
Contents
vii
5. Viable Microbial Allergens ........................................................................ 67
Occurrence of Allergenic Microbes.............................................................. 67
Fungi ........................................................................................................... 68
Molds .......................................................................................................... 68
Yeasts........................................................................................................... 72
Bacteria ....................................................................................................... 72
Bacillus................................................................................................... 73
Thermophilic Actinomycetes ............................................................. 74
Air Sampling Methodologies....................................................................... 74
Sampling Strategy..................................................................................... 75
When and Where to Sample ............................................................... 75
Equipment ............................................................................................. 76
Sample Duration................................................................................... 78
Sample Numbers .................................................................................. 78
Culture Media....................................................................................... 79
Procedural Summary...........................................................................83
Diagnostic Sampling Methodologies..........................................................83
Sampling Strategy.....................................................................................84
Where to Sample .......................................................................................84
What to Sample .........................................................................................85
Sampling Supplies ....................................................................................85
Procedural Summary ............................................................................... 86
Interpretation of Results ............................................................................... 86
Genus Variability ...................................................................................... 87
Airborne Exposure Levels ....................................................................... 89
Bulk and Surface Sample Results ........................................................... 89
Helpful Hints..................................................................................................90
Summary.........................................................................................................90
References ....................................................................................................... 91
6. Pathogenic Microbes.................................................................................... 93
Airborne Pathogenic Fungi .......................................................................... 94
Disease and Occurrence........................................................................... 94
Aspergillus .............................................................................................. 94
Histoplasma capsulatum ......................................................................... 96
Coccidioides immitis ............................................................................... 97
Cryptococcus neoformans ....................................................................... 99
Other Pathogenic Fungi ...................................................................... 99
Sampling and Analytical Methodologies............................................ 102
Interpretation of Results ........................................................................ 103
Airborne Pathogenic Bacteria .................................................................... 103
Pathogenic Legionella................................................................................ 104
Sampling and Analytical Methodologies for Legionella ............... 105
Interpretation of Results.................................................................... 106
Helpful Hints ...................................................................................... 107
viii
Contents
Other Pathogenic Bacteria ..................................................................... 108
Disease and Occurrence of Prominent Airborne Pathogenic
Bacteria ................................................................................................ 108
Sampling and Analytical Methodologies............................................ 111
Interpretation of Results.................................................................... 112
Pathogenic Protozoa .................................................................................... 113
Sampling and Analytical Methodology .............................................. 113
Interpretation of Results ........................................................................ 114
Viruses........................................................................................................... 114
Summary....................................................................................................... 115
References ..................................................................................................... 115
7. Toxigenic Microbes .................................................................................... 119
Mycotoxins.................................................................................................... 119
Disease and Occurrence......................................................................... 121
Sampling and Analytical Methodologies............................................ 123
Fungi Identification............................................................................ 123
Toxin Identification ............................................................................ 124
Interpretation of Results ........................................................................ 126
Bacterial Endotoxins.................................................................................... 127
Sampling and Analytical Methodology .............................................. 128
Interpretation of Results ........................................................................ 130
Summary....................................................................................................... 131
References ..................................................................................................... 131
Section III Chemical Unknowns and Gases
8. Volatile Organic Compounds .................................................................. 135
Health Effects and Occurrences ................................................................ 136
Air Sampling Strategy................................................................................. 139
When to Sample ...................................................................................... 139
Where to Sample ..................................................................................... 140
How to Sample ........................................................................................ 141
Rationale for Total VOC Screening (As Opposed to Component
Identification)................................................................................................ 141
Air Sampling and Analytical Methodologies.......................................... 143
Solid Sorbents and Air Sampling Pumps............................................ 145
NIOSH Method 1500.......................................................................... 145
EPA Method TO-17............................................................................. 147
Passive Organic Vapor Monitors...................................................... 149
Evacuated Ambient Air Containers ................................................ 151
Whole Air Canisters .......................................................................... 152
Ambient Air Sampling Bags ............................................................ 154
Contents
ix
Analytical Comparisons ........................................................................ 156
Helpful Hints ...................................................................................... 158
Interpretation of Results.................................................................... 159
Summary....................................................................................................... 161
References ..................................................................................................... 161
9. Mold Volatile Organic Compounds and Mold Detection.................. 163
Health Effects and Occurrences ................................................................ 163
Sampling for MVOCs .................................................................................. 166
Sampling Strategy................................................................................... 166
Sampling Methodology.......................................................................... 167
Screening Methodologies ........................................................................... 168
Visual Observations................................................................................ 168
Odor Tracking.......................................................................................... 170
Moisture Testing ..................................................................................... 171
Interpretation of Results ............................................................................. 173
Summary....................................................................................................... 174
References ..................................................................................................... 174
10. Carbon Dioxide ........................................................................................... 177
Occurrence of Carbon Dioxide .................................................................. 178
Sampling Strategy........................................................................................ 179
Sampling Methodologies............................................................................ 180
Direct Reading Instrumentation........................................................... 180
Colorimetric Detectors ........................................................................... 180
Helpful Hints................................................................................................ 182
Interpretation of Results ............................................................................. 183
Summary....................................................................................................... 184
11. Carbon Monoxide ....................................................................................... 185
Occurrence of Carbon Monoxide .............................................................. 185
Sampling Strategy........................................................................................ 187
Sampling Methodologies............................................................................ 188
Direct Reading Instrumentation........................................................... 188
Colorimetric Detectors ........................................................................... 188
Helpful Hints................................................................................................ 190
Interpretation of Results ............................................................................. 190
Summary....................................................................................................... 191
Reference ....................................................................................................... 191
12. Formaldehyde .............................................................................................. 193
Occurrence of Formaldehyde..................................................................... 194
Sampling Strategy........................................................................................ 196
Sampling Methodologies............................................................................ 197
Analytical Methodologies .......................................................................... 201
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Contents
Helpful Hints................................................................................................ 202
Interpretation of Results ............................................................................. 202
Summary....................................................................................................... 203
References ..................................................................................................... 203
13. Product Emissions ...................................................................................... 205
Global Response and Product Labelling .................................................. 206
Product Emissions Awareness................................................................... 208
Sensory Irritation Testing in Environmental Chambers ....................... 211
Product Collection ....................................................................................... 212
Environmental Chamber and Analytical Methodology........................ 216
Measurements of Product Emission Factors............................................ 219
Interpretation of Results ............................................................................. 220
Summary.......................................................................................................223
References .....................................................................................................225
Section IV Identification of Dusts
14. Forensics of Dust ........................................................................................ 229
Occurrences of Forensic Dust .................................................................... 230
Sampling Methodologies............................................................................ 232
Settled Surface Dust Sampling .............................................................234
Specialty Tape .....................................................................................234
Clear Tape............................................................................................ 235
Post-it Paper......................................................................................... 235
Micro-vacuuming............................................................................... 235
Airborne Dust Sampling........................................................................ 236
Spore Trap ................................................................................................ 236
Membrane Filters................................................................................ 237
Cascade Impactors ............................................................................. 238
Other Methods.................................................................................... 238
Bulk Sampling ......................................................................................... 239
Textile/Carpet Sampling........................................................................ 239
Analytical Methodologies .......................................................................... 240
Visible Light Microscopy ....................................................................... 240
Specialized Microscopic Techniques ................................................... 241
X-Ray Diffraction................................................................................ 241
Scanning Electron Microscope......................................................... 242
Transmission Electron Microscope................................................... 243
Electron Microprobe Analyzer......................................................... 244
Ion Microprobe Analyzer.................................................................. 244
Commercial Laboratories ........................................................................... 245
Summary....................................................................................................... 245
References ..................................................................................................... 246
Contents
xi
15. Animal Allergenic Dust............................................................................ 247
Animal Allergens ........................................................................................ 248
Mites/Spiders........................................................................................... 248
Booklice .................................................................................................... 251
Cockroaches and Other Insects ............................................................ 251
Domestic Animals ..................................................................................254
Cats ....................................................................................................... 255
Dogs...................................................................................................... 255
Rodents ................................................................................................ 256
Farm Animals ..................................................................................... 257
Other Animals .................................................................................... 257
Occurrence of Animal Allergens............................................................... 257
Sampling Strategy........................................................................................ 258
Screening for Rodents ................................................................................. 260
Sampling Methodologies............................................................................ 260
Analytical Methodologies .......................................................................... 263
Human Testing........................................................................................ 263
Allergenic Dust Testing........................................................................... 264
Interpretation of Results ............................................................................. 265
Other Types of Allergenic Substances ...................................................... 268
Summary....................................................................................................... 269
References ..................................................................................................... 270
Section V Building Systems and Materials
16. HVAC Systems ............................................................................................ 275
The Basic Design .......................................................................................... 275
HVAC Visual Inspection............................................................................. 278
Outdoor Air Intake ................................................................................. 278
Outdoor Air in the Vicinity of Air Intake ........................................... 279
Indoor HVAC Equipment Rooms ......................................................... 279
Filters.......................................................................................................... 279
Condensate Drain Pan............................................................................ 282
Fan Housing.............................................................................................284
Unit and Duct Liner................................................................................284
Supply Registers and Return Air Grills............................................... 286
Level of Maintenance ............................................................................. 288
Air Duct.................................................................................................... 289
Strategy and Sampling................................................................................ 290
Analyzing the Unknown ............................................................................ 292
Interpretation Not So Simple ..................................................................... 292
Summary....................................................................................................... 293
xii
Contents
17. Sewage Systems and Sewer Gases .......................................................... 295
Occurrence of Sewer Gases ........................................................................ 296
Hazardous Gases .................................................................................... 296
Biological Components........................................................................... 297
Noxious Odor Confusion....................................................................... 297
Investigation Procedures ............................................................................ 298
Air Sampling............................................................................................. 299
Identification of Components ........................................................... 299
Tracking Sewer Gases........................................................................ 299
Sewage System Inspection Awareness ................................................300
Poorly Installed Sewer Vents ............................................................300
Plumbing Fixtures and Associated Traps....................................... 301
In-Foundation Line Breaks ............................................................... 301
Septic/Sewage Drains and Lines ..................................................... 302
Interpretation of Results ............................................................................. 302
Summary....................................................................................................... 303
18. Tainted Chinese Drywall .........................................................................305
Health Effects ...............................................................................................306
Screening Considerations ...........................................................................308
Homeowner Assessment .......................................................................308
Inspection Screening ..............................................................................308
Components of Chinese Drywall ..............................................................309
Sampling and Analytical Methodologies.................................................. 311
Bulk Sample Collection and Analysis for Identification
of Chinese Drywall................................................................................. 311
Sample Collection............................................................................... 311
Sample Analysis ................................................................................. 312
Suspect Air and Headspace Sampling for Off-Gassing
Components ............................................................................................. 313
Sample Collection............................................................................... 313
Sample Analyses ................................................................................ 314
Corrosion Testing .................................................................................... 315
Sample Collection............................................................................... 315
Microbiological Testing.......................................................................... 316
Interpretation of Results ............................................................................. 317
Chinese Manufactured Drywall........................................................... 317
Off-Gassing Sulfur-Containing Gases................................................. 317
Causes Corrosion .................................................................................... 318
Summary....................................................................................................... 318
References ..................................................................................................... 319
19. Green Buildings.......................................................................................... 321
21st Century Green ...................................................................................... 322
Green Flush-Out Protocols ......................................................................... 323
Contents
xiii
LEED Indoor Air Quality Management Plan ..................................... 324
ANSI/ASHRAE Standard 189.1—Construction and Plans
for Operation ........................................................................................... 324
Sampling and Analytical Methodologies.................................................. 325
Interpretation of Results ............................................................................. 331
Summary.......................................................................................................334
References .....................................................................................................334
Glossary ............................................................................................................... 335
Appendix A: Abbreviations/Acronyms.........................................................345
Appendix B: Units of Measurement .............................................................. 347
Appendix C: Allergy Symptoms...................................................................... 349
Appendix D: Classification Volatile Organic Compounds ....................... 353
Preface
With the new millennium comes change. Indoor air quality methodologies
have expanded, evolved, and morphed. The focus is shifting from a knee-jerk
to a more proactive response. Although indoor air quality in older buildings
will continue to present old challenges, new construction is going forward
with new challenges.
The intent of this book is to provide environmental professionals, industrial hygienists, and indoor air quality specialists with the latest and greatest methods in response to the knee-jerk indoor air quality challenges and
for assessing new construction prior to occupancy. The focus is to provide
a “practical guide” for developing a theory and following it through to the
identification and interpretation of unknown air contaminants.
Section I, “The Starting Line,” provides a historic overview with regulatory
limits and guidelines; preliminary investigation methods including means
for assessing complaints; and a means for speculation, narrowing the hunt
for offenders. With a well-defined hypothesis, the investigator must test the
hypothesis by sampling. Direction is provided for determining what, when,
where, and how to sample for the various airborne components that may
be found in indoor air quality situations. The components are broken into
bioaerosols, chemicals, and dust.
Section II, “Omnipresent Bioaerosols,” is inclusive of microbials only. This
section discusses sampling methodologies for microbial allergens such as fungi
and pollen; invasive pathogenic microbes; and toxigenic molds/bacteria. Other
biological components such as animal allergens are contained within another
section.
Section III, “Chemical Unknowns and Gases,” contains sampling methodologies for volatile organic compounds; microbial volatile organic compounds;
carbon dioxide; carbon monoxide; formaldehyde; and product emissions.
The microbial volatile organic compounds are discussed within this section
because some researchers speculate that microbial (e.g., mold) by-products
may contribute to the total volatile organic compounds in an enclosed building. Yet some use the techniques to locate mold in wall spaces.
Section IV, “Identification of Dusts,” contains sampling methodologies for
animal allergens such as dust mites and forensic methods for identifying
dust components. Dust components can be checked for chemicals adsorbed
onto or settled on the surface of dust particles, toxic metals, and various
types of fibers (e.g., resin-coated fiberglass).
Section V, “Building Systems and Materials,” is a new section. Often overlooked and underutilized, sewage gases and HVAC systems are discussed
and assessment guidelines provided. The topic of tainted Chinese drywall
has become a bucket of worms—legally, financially, and analytically. In the
xv
xvi
Preface
chapter “Tainted Chinese Drywall,” the background information and more
prominent sampling methodologies are discussed. The last chapter is “Green
Buildings.” The concept of green buildings has shifted from resource conservation only to resource conservation and healthy indoor air quality. The
Leadership in Energy and Environmental Design (LEED) Rating System and
American Society of Heating, Refrigerating and Air Conditioning Engineers
(ASHRAE) 189.1 are discussed, and air sampling methodologies and sample
limits are detailed.
As a passion for detective work is a delightful motivator for performing an
indoor air quality assessment, the person performing such a survey is herein
referred to as the “investigator.” The investigator’s greatest asset is his or her
ability to weave through a convoluted web of complex problems. This book
provides strategies and tools to herald Sherlock Holmes!
Acknowledgments
I wish to dedicate this book to those who have contributed their time and
technical expertise to review and update technical information that is
constantly changing. A special thanks to Sean Abbott, PhD, mycologist
extraordinaire and director of Natural Link Mold Lab, for reviewing the
extensive section on bioaerosols. Paul Pope, MS, analytical chemist for ALS
Laboratory Group, made whole the table on EPA air monitoring methodologies, reviewed “Green Buildings”, and shared his company’s unique
findings regarding tainted Chinese drywall. He truly has been an invaluable resource of all information—established and evolving. Vince Delessio
with EMSL provided information regarding tainted Chinese drywall as
well, and Marilyn Black, PhD, with Air Quality Services reviewed the
evolving chapter on “Product Emissions.” Each of these contributors has
been patient, withstanding my endless questions and ceaseless requests
for data.
Last, but certainly not least, my husband has been my rock of sanity in
the final throes of a topic that changes daily. As my dog runs in circles, the
house is in disarray, and the world races on, I offer my gratitude and heartfelt
thanks to all!
xvii
About the Author
Kathleen Hess-Kosa is the president/owner of Omega Southwest Enviro­
nmental Consulting. In 1972, she received her bachelor of science degree in
microbiology with a minor in chemistry from Oklahoma State University.
After serving as an officer in the Air Force for three years, she returned to
school and earned a master of science degree (1979) in industrial hygiene
from the College of Engineering at Texas A&M University. Her research
involved an animal toxicological study and was conducted at the College
of Veterinary Sciences.
Hess-Kosa worked as a consultant for Firemen’s Fund Insurance Companies
until 1984. This was shortly after she passed the certification exam conducted
by the American Board of Industrial Hygiene. During these five years,
Hess-Kosa had the opportunity to become involved in a variety of unique
industrial hygiene and environmental concerns, including indoor air quality concerns in an 800-occupant office building and information gathering
for performing environmental site assessments and assessing waste. All this
and much more carried over to her private consulting business.
Hess-Kosa has since conducted numerous Phase I environmental site
assessments and published a book concerning the topic. She has actively
pursued obscure sources of information and training to better address the
complex nature of environmental issues, indoor air quality, and multiple
chemical sensitivity. She has successfully identified sources of indoor air
quality problems in more than 90 percent of the numerous investigations
performed, and she has been instrumental in rectifying 100 percent of the
scenarios. It took some time to get to this point, but some of the information
that was collected and has been used by Hess-Kosa is presented within this
book.
xix
Section I
The Starting Line
1
Historic Overview
An estimated 1.34 million office buildings have problems with air quality, and approximately 30 percent of all office employees are potentially
exposed to the health effects of poor indoor air quality.1 More than 50 million
Americans suffer from asthma, allergies, and hay fever. Chronic bronchitis
and emphysema increased by more than 85 percent between 1970 and 1987.
Close to 100,000 Americans die each year because of complications due to
chronic obstructive pulmonary diseases (COPD).1 More than 50 percent of
our nation’s schools have poor ventilation and significant sources of pollution in buildings, where an estimated 55 million students and school staff
members are affected by poor air quality. Health effects are predominantly
observed in children with asthma. In the last 15 years, a 60 percent increase
in the incidence of asthma has occurred amongst school-aged children.
Today approximately 8 percent of all school-aged children have been diagnosed with asthma.
In an effort to address many of the prevailing and ever-looming issues,
indoor air quality investigative methodologies are evolving. Indoor air quality is complex!
Many indoor air quality situations culminate with litigation, differences in
health impact, differences in perceived health effects, regulatory limits, and
guidelines. Guidelines are being created by recognized public agencies, and
investigators are being called upon to make decisions with minimal support
and direction. Finally, indoor air quality investigations are becoming more
proactive, part and parcel of the new “healthy” green buildings.
Evolution of Indoor Air Quality Investigations
The Environmental Protection Agency (EPA) ranks indoor air pollution
among the top four environmental risks in America. People spend about
90 percent of their lives indoors, and pollution is consistently two to five
times higher indoors than outdoors. The indoor pollutant levels have been
reported as high as 100 times the levels encountered outside.
Since the worldwide energy crisis in 1973, advances in energy efficiency
building construction have not been without a downside. In an effort to
conserve fuel in commercial and residential buildings, builders started
3
4
Indoor Air Quality: The Latest Sampling and Analytical Methods
constructing airtight buildings, inoperable airtight windows, and reduced
air exchange rates.
In well-weatherized homes, the air exchange rate is 0.2 to 0.3 air changes
per hour. In older, less energy efficient homes, exchange rates are as high as
2 changes per hour. In energy efficient office buildings, air exchange rates
are around 0.29 to 1.73 changes per hour. The higher exchange rates in older
buildings dilute and clean indoor air contaminants, whereas the newer
buildings retain them. Thus, illness associated with new buildings has come
to be referred to as “tight building syndrome.”
By 1986 the news media began to sensationalize the condition and coined
the term “sick building syndrome.” Sick building syndrome is a condition
whereby the occupants of a building experience health and comfort problems that seem to be linked to a building, and the cause is unknown. Indoor
air quality investigative methods to identify unknown sources of buildingrelated health complaints have continued to evolve.
At the low end of the evolutionary scale, formaldehyde off-gassing from
furnishings in office buildings and from particleboard in mobile homes was
targeted as the single most investigated culprit. One article, published in 1987,
refers to formaldehyde as a “deadly sin.” New media touted, “It Could Be
Your Office That Is Sick,” “Tight Homes, Bad Air,” and “The Enemy Within.”
Sensational! Insurance claims were on the rise, and insurance companies began
to exclude “claims arising directly or indirectly out of formaldehyde whether or
not the formaldehyde is airborne as a fiber or particle, contained in a product,
carried or transmitted on clothing contained in or a part of any building, building material, insulation product or any component part of any building.”
With the passage of time it became clear that the problem was not a simple one, and looking for unknowns was not a simple process. As industrial
hygienists scrambled to identify other possibilities, office building investigations became research projects. The cost was in the thousands of dollars.
Ongoing complaints recurred, and ultimately the industrial hygiene profession pioneered the investigative and sampling methodologies that are in
play today.
The original hit list evolved to include not only formaldehyde but carbon monoxide, carbon dioxide (fresh air/indicator gas), and total organics.
Industrial hygienists further attempted to identify volatile organic compounds (VOC). Many began looking at carpet emissions (e.g., 4-phenylcyclohexene), tobacco smoke, and airborne/surface allergens. All things were
possible. All possibilities were “open for discussion.”
In the latter part of the 20th century, residential concerns were being
addressed with greater frequency. Considerations for sampling included
formaldehyde, carbon monoxide, carbon dioxide, allergens, electromagnetic
radiation, radon, and a medley of household products (e.g., VOC).
By 2000, mold became the new “hot topic.” The focus shifted from formaldehyde and other chemicals to mold. Media headlines heralded, “The Dish
on Hotel Air,” “Moldy Attitudes on Indoor Air Need a Good Scrubbing,”
Historic Overview
5
“The Good, The Bad and The Moldy,” and “Fungal Sleuths.” The shift was
phenomenal. In the public’s eye, mold had become the single most cause of
indoor air quality complaints. This was a little shortsighted, yet it was the
perceived reality. Requests to perform indoor air quality studies were equivalent to a “mold study” even when it wasn’t visibly apparent. Many in the
public had turned a blind eye to other possibilities.
In many cases, when the elusive mold blame game failed and complaints
persisted, investigators were forced to revert back to the basics and carpet
emissions. Yet even today very few investigators go the extra mile of spending the extra money to identify VOC components and to consider other possibilities (e.g., forensic dust and fine particles). Other considerations became
emissions from copy machines, sewer gases, ozone, and outdoor air. The latest concern has been tainted Chinese drywall.
In the 21st century, “green buildings” have become the focus. Although
energy and resource conservation were the primary concern, healthy
buildings began to take on a whole new complexion. Green buildings are
becoming synonymous with healthy buildings. Product emissions testing
and green certification of products has raced to the forefront, beginning
to parallel green building concerns, and indoor air quality standards for
high-performance (e.g., office) buildings have been proposed as of 2009.
The wave of the future is for buildings to be assessed as a unit. Building
systems and materials are seen as a total package. The swath of complexities
is great. Indoor air quality challenges are many, and guidelines are being
developed. The future is now!
Litigation
Managing indoor air quality has become one of the more demanding challenges facing school administrators and potentially office facility managers.
Legal action, negotiation, and arbitration have redefined what is considered
as acceptable. An acceptable response to indoor air quality complaints thus
has come to be defined in terms of reasonable standard of care.
If a student or faculty member initiates an indoor air quality claim against
a school, the person must establish certain facts. First, the claim must demonstrate that the school has a duty to protect faculty from reasonably foreseeable harm. Second, after having demonstrated the existence of a duty, the
claimant must demonstrate that the school failed to provide a reasonable
standard of care. This constitutes negligence. For example, if a staff member reports building-related health symptoms, and the administrators fail to
show a reasonable standard of care, ignoring the complaint would constitute
a clear failure to show reasonable care. Third, the breach must be directly
related to the harm claimed. Recently the term sick building syndrome has
6
Indoor Air Quality: The Latest Sampling and Analytical Methods
come to mean that a building is causing health problems, and the source is
unknown.2
In the court case of Dean H.M. Chenensky et al. v. Glenwood Management
Corp. et al., there is a pending lawsuit involving $180 million regarding mold
exposures. In another case, Robert E. Coiro et al. v. Dormitory Authority of the
State of New York, the plaintiffs are seeking $65 million. Other suits involving
various indoor air quality allegations are ongoing.
Thus, the driving force in indoor air quality investigations has become fear
of litigation. The cost of a thorough indoor air quality investigation is small
as compared to the cost of litigation.
Differences in Health Effects
The health effects of poor indoor air quality are dependent upon several factors. Relevant considerations when determining potential health effects on a
population are the effect of each air contaminant, concentration, duration of
exposure, and individual sensitivity.
The air contaminant may be an allergen, or it may be a carcinogenic chemical.
The allergen will cause an immediate reaction with minimal long-term effects.
A carcinogenic chemical may not have any warning signs of exposure but may
cause cancer years after exposure. It may be an irritant with passing health
effects, or it may be a sensitizing chemical (e.g., isocyanates) whereby future
exposures may result in an extreme immune response. Indoor air generally
consists of a complex medley of substances that may have one or a combination
of effects, and those substances that have the same health effect may not singularly cause health problems, whereas two different substances (e.g., irritants)
may significantly impact human health when present at the same time.
Proper diagnosis is of course dependent upon proper identification of all
contributing components. Then, once the contaminants have been identified,
concentration should be ascertained.
Although there are known concentrations for many air contaminants at
which well-defined health effects become evident, exposure levels defining
the more subtle health effects are not as well-researched. Furthermore, of the
estimated 100,000 toxic substances to which building occupants are potentially exposed, fewer than 400 recommended exposure limits exist for industrial chemicals. The Occupational Safety and Health Administration (OSHA)
regulates industry and EPA regulates outdoor ambient air quality. Currently,
no regulatory agencies control indoor air quality exposure limits.
Exposure duration is of particular concern in assessing indoor air quality
exposures. In office buildings, exposures are generally 8 to 10 hours a day,
five days a week. In residential structures, exposures may be up to 24 hours
a day, seven days a week. As some substances build up in the body over
Historic Overview
7
time, 24-hour exposures may result in an accumulation with the subsequent
impact on health effects. Thus, the impact of a given concentration of air
contaminant is less in office buildings than in residences. Other areas that
should be considered potential long duration exposures include hospital
patient rooms, hotels, mental wards, and prison cells.
Individual sensitivity contributes a huge variable to the combination of
factors affecting the health of building occupants. Infants, elderly people,
and sickly people are the most vulnerable to the health effects of air contaminants. Immune-suppressed individuals (e.g., AIDS patients and organ transplant recipients) and those with genetic diseases (e.g., lupus erythematosus)
are particularly sensitive to common molds. Individuals who drink alcohol
in excess are more susceptible to air contaminants that may affect the liver.
People with dry skin are more susceptible to further drying and skin penetration by chemicals. Those who smoke tobacco products have diminished
body defense mechanisms. Certain medications enhance the effect of environmental exposures. Individuals with predisposed conditions (e.g., lungs
damaged by fire) may have a heightened response to air contaminants.
A Misguided Premise
As they compare the indoor to industrial environments, traditional industrial hygienists see the good, the bad, and the ugly. The indoor air quality
environment is the good, and industrial environments are the bad and ugly.
This is a misguided premise that requires comment.
Indoor air quality exposures involve multiple exposures to unknown substances in enclosed environments often with minimal fresh air, no exposure
duration limits, and a wide range of individual susceptibility. Industrial
exposures involve limited exposures to known chemicals in work environments with local exhaust ventilation, limited exposure duration, and healthy
adults. The indoor environment does not begin to compare to the dirt and
grime of industry. Yet clearly there are differences.
A tight building has multiple factors that can result in sick building syndrome. An enclosed environment does not mean clean air.
Regulations, Requirements, and Guidelines
Currently, federal regulatory limits for indoor air quality are limited. U.S.
government directives are limited in scope. The EPA Ambient Air Quality
Standards are limited to outdoor environmental pollution, and OSHA
8
Indoor Air Quality: The Latest Sampling and Analytical Methods
mandates are limited to industrial pollution. Yet these regulated limits have
been found inadequate or marginal at best in responding to cases involving
indoor air quality.
In an effort to stem the tide of indoor air quality health complaints, various
recognized public contributors have recommended guidelines. Regulatory
standards are mandated and guidelines are recommended. The recommended guidelines are more apt to appropriately address indoor air quality
problems than are regulatory standards.
Guidelines are developed, reviewed, and updated by professional experts
and are frequently cited. Formal guidelines of national importance are the
American Conference of Governmental Industrial Hygienists (ACGIH)
and the American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE), and there are some international contributors.
U.S. Government Directives
A limited number of federal agencies have been given directives to consider
indoor air quality in their standards. In 1994, the Department of Energy was
directed to consider the impact of energy efficient options on habitability and
people, and to achieve a balance between a healthy environment and energy
conservation.3 In 1997, the Department of Housing and Urban Development
promulgated standards for the construction and safety of manufactured
housing that includes features related to indoor air quality.4
EPA National Ambient Air Quality Standards
The EPA air quality focus is to protect human health outdoors in the ambient air. The principal program that may be of some value to the reader is
the National Ambient Air Quality Standard. The intent of this standard is
to control emissions of six pollutants and their precursors when released in
large quantities (e.g., vehicle exhausts and industrial emissions). This standard may be applied in indoor air quality investigations where the outside
air may potentially contribute to exposure levels indoors, such as in large
nonattainment cities. Nonattainment means the city does not comply with
one or a combination of the air quality standards as set forth in Table 1.1.
Where exceeded outdoors, the National Ambient Air Quality Standards are
likely to be exceeded indoors as well.
Nonattainment areas are generally around large cities (e.g., Los Angeles
and New York City) and industrial areas (e.g., New Jersey), but nonattainment
sites are sometimes encountered in unpredictable, isolated areas. They are
designated by state and county, and the regional EPA office can provide the
latest information upon request.
9
Historic Overview
TABLE 1.1
National Ambient Air Quality Standards (NAAQS)
Pollutant
Carbon monoxide
Lead
Nitrogen dioxide
Particulate matter
(PM10)
Particulate matter
(PM2.5)
Primary Stds.
9 ppm (10 mg/m )
35 ppm (40 mg/m3)
1.5 µg/m3
0.053 ppm (100 µg/m3)
3
revokedb
150 µg/m3
35 µg/m3
Ozone
0.08 ppm
0.12 ppm
Sulfur oxides
0.03 ppm
0.14 ppm
a
b
c
d
e
f
g
Averaging Times
Secondary Stds.
8-hour
1-houra
Quarterly average
Annual (arithmetic
mean)
—
none
none
same as primary
same as primary
24-hourc
Annuald (arithmetic
mean)
24-houre
8-hourf
1-hourg
(Applies only in
limited areas)
24-houra
3-houra
—
same as primary
a
—
—
same as primary
same as primary
—
—
0.5 ppm (1300 µg/m3)
Not to be exceeded more than once per year.
Due to lack of evidence linking health problems to long-term exposure to coarse particle
pollution, the agency revoked the annual PM10 standard in 2006 (effective December 17, 2006).
Not to be exceeded more than once per year on average over three years.
To attain this standard, the three-year average of the weighted annual mean PM2.5 concentrations from single or multiple community-oriented monitors must not exceed 15.0 µg/m3.
To attain this standard, the three-year average of the 98th percentile of 24-hour concentrations
at each population-oriented monitor within an area must not exceed 35 µg/m3 (effective
December 17, 2006).
To attain this standard, the three-year average of the fourth-highest daily maximum 8-hour
average ozone concentrations measured at each monitoring station within an area over each
year must not exceed 0.08 ppm.
(a) The standard is attained when the expected number of days per calendar year with maximum hourly average concentrations above 0.012 is <1, as determined by Appendix H. (b) As
of June 15, 2005, the EPA revoked the 1-hour ozone standard in all areas except the 14 8-hour
ozone nonattainment Early Action Compact (EAC) areas.
OSHA Workplace Standards
OSHA claims jurisdiction over all workplace environments. The workplace includes indoor air quality exposures in office buildings as well as in
industry and construction. Yet when it comes to indoor air quality, OSHA
capabilities are limited in that the contaminants must be known and permissible exposure limits are based on outdated limits published by ACGIH
in 1968.
10
Indoor Air Quality: The Latest Sampling and Analytical Methods
Not only are most OSHA limits easily attained in indoor air quality investigations, but there are no provisions for low-level irritants, molds, and allergens. Those investigators who do insist on applying the OSHA standards in
office environments will generally find a dead-end street. These same investigators often state that the OSHA standards have been met so there must not
be a problem. In a building where 80 percent of the occupants have health
complaints, a statement that infers the only problem is mass hysteria will
most assuredly find the investigator’s credibility questioned. The original
OSHA exposure limits were derived from the 1968 ACGIH recommendations. Limits for only a handful of chemical contaminants (e.g., asbestos and
benzene) have since been updated. For this reason, most industrial hygienists consider OSHA limits outdated and opt to use the ACGIH guidelines.
Although backed up by the force of federal law, the OSHA limits are rarely
exceeded in office environments where one or more of the contaminants
have been properly identified. The complex nature of indoor air quality is
not supported by OSHA limits.
ACGIH Workplace Guidelines
The American Conference of Governmental Industrial Hygienists (ACGIH)
is a professional society of scientists that annually reviews and recommends
guidelines to industrial hygienists for use in the assessment of occupational
workplace exposures.
The American Conference of Governmental Industrial Hygienists
(ACGIH) limits are intended for use in the practice of industrial hygiene
as guidelines or recommendations in the control of potential workplace
health hazards and for no other use. … These limits are not fine lines
between safe and dangerous concentrations nor are they a relative index
of toxicity. … A small percentage of workers may experience discomfort
from some substances at concentrations at or below the threshold limit,
and a smaller percentage may be affected more seriously by aggravation of a pre-existing condition or by development of an occupational
illness.
There are around 400 chemicals listed with recommended 15 minute and
8-hour exposure limits. These guidelines were created to address exposures
in the workplace. Occupational exposures are generally limited to 8-hour
exposure durations for healthy adults between the ages of 18 and 65. Thus,
the ACGIH exposure guidelines do not apply to residential exposures where
the exposure parameters differ. ASHRAE has addressed this consideration.
ASHRAE Criteria for General Public5
In 1981, The American Society of Heating, Refrigeration and Air Conditioning
(ASHRAE) introduced a revised mechanical ventilation standard that is now
Historic Overview
11
referred to as the “Ventilation for Acceptable Indoor Air Quality Standard.”
ASHRAE developed and evolved consensus guidelines to address indoor air
quality in public buildings.
Consensus is defined as “substantial agreement reached by directly and
materially affected interest categories. This signifies the concurrence of more
than a simple majority, but not necessarily unanimity. Consensus requires
that all views and objections be considered, and that an effort be made
toward their resolution. Compliance with this is voluntary until and unless
a legal jurisdiction makes compliance mandatory through legislation.” This
definition is according to the American National Standards Institute (ANSI),
of which ASHRAE is a member.6
The purpose of the standard is to “specify minimum ventilation rates
and indoor air quality that will be acceptable to human occupants and are
intended to avoid adverse health effects.” The health effects information and
acceptable exposure limits rely on recognized authorities and their recommendations. Thus, the ASHRAE standard on “Ventilation for Acceptable
Indoor Air Quality” has become the most commonly cited guideline for
investigating indoor air quality in commercial and institutional facilities in
the world.
The standard is intended to provide ventilation design and maintenance
practices for air handling systems except where more stringent design
specifications apply. It should also be noted that in 1999, ASHRAE issued
a disclaimer that “acceptable indoor air quality may not be achieved in all
buildings meeting the requirements of this standard.”5 The 2007 disclaimer
has been slightly altered to reflect “any tests conducted under its Standards
or Guidelines will be nonhazardous or free from risk.”6
ACGIH Guidelines Revisited in Older ASHRAE Standard
In a 1999 publication, ASHRAE recommended the investigator start with
an acceptable limit of one-tenth of the ACGIH TLVs for acceptable indoor
air quality.
A concentration of 1/10 TLV would not produce complaints in nonindustrial population(s) in residential, office, school, or other similar
environments. The 1/10 TLV may not provide an environment satisfactory to individuals who are extremely sensitive to an irritant. … Where
standards or guidelines do not exist, expert help should be sought in
evaluating what level of such a chemical or combination of chemicals
would be acceptable.7
This recommendation has not continued to the succeeding publications,
but it has been referred to by the California Relative Exposure Limits (REL)
for individual organic compounds. The California REL is frequently deferred
to in assessing product emissions.
12
Indoor Air Quality: The Latest Sampling and Analytical Methods
International Enforcement and/or Guidelines
In ANSI/ASHRAE 62.1-2007, “Ventilation for Acceptable Indoor Air Quality,”
outdoor and indoor enforceable regulatory limits and nonenforceable guidance limits are listed in Appendix B, Table B-1, of the Standard. The Canadian
maximum exposure limits are for residences. The Environmental Protection
Agency (EPA) and World Health Organization (WHO) limits are for indoor
and outdoor exposures. All others are for outdoors environmental air or
industrial exposures only. The Canadian limits tend to be the lowest, more
difficult to attain.
ASHRAE Criteria for Residences
ANSI/ASHRAE 62.2-2007, “Ventilation for Acceptable Indoor Air Quality
in Low-Rise Residential Buildings,” is the only ASHRAE standard that
addresses residential indoor air quality, but it does not address acceptable
air quality issues as do the ANSI/ASHRAE 62.1 series for office buildings.
The standard merely sets guidelines to achieve acceptable indoor air quality
for homes by ensuring minimum ventilation. Its purpose is to address only
mechanical ventilation by means of:
• Source control of moisture and other specific improvements through
the use of exhaust fans
• Local ventilation in wet rooms to remove odor and moisture
• Carbon monoxide detectors
• Criteria to minimize back-drafting and other combustion-related
contaminants
• Provision to reduce contamination from attached garages
• Guidance on how to select, install, and operate systems
As there are no actual recommended ASHRAE standards for residences,
the office building standards (ANSI/ASHRAE 62.1-2007 and 189.1) may be
referred to for guidance.
ASHRAE Criteria for High Performance Buildings
In 2010, ASHRAE published a “Standard for the Design of High-Performance,
Green Buildings—Except Low-Rise Residential Buildings.” In this publication, recommended air quality limits are lower than or equal to all U.S. and
international standards.
The intent was to pave the way for more energy efficiency/resource conservation and to provide for healthy building construction that requires
indoor air quality testing. Whereas the 1998 Leadership in Energy and
Environmental Design (LEED) rating proposes an option to perform indoor
Historic Overview
13
air quality testing, ASHRAE 189.1 mandates air testing after construction,
prior to occupancy of high-performance (e.g., office) green buildings. For
more information and details, see Chapter 19, “Green Buildings.”
Summary
Tight building syndrome and sick building syndrome have become household phrases. As indoor air quality complaints escalate, ignored health
complaints in public buildings are becoming the rationale for lawsuits and
homeowners are living in fear. In an effort to stem the tide, environmental
professionals are developing guidelines and recommendations that specifically address indoor air quality.
Indoor air quality investigations have yet to be standardized, regulated,
or managed with consistency. Thus, those performing these investigations
must develop a strong knowledge base and actively pursue each new case
with the enquiring mind of a detective.
References
1. USA Today. Struggling to diagnose sick buildings. usatoday.com/life/health/
generaVlhgen253.htm (July 20, 2000).
2. Hays, L. Lawsuits in the Air. American School & University. 72(10):35 (June
2000).
3. Energy Conservation and Production Act, Pub. L. No. 94 385, 90 Stat. 1125
(1976); 12 U.S.C. section 1701z 8 (1994); 15 U.S.C. section 787 (1994); 42 U.S.C.
sections 787 790 (1994); 42 U.S.C. sections 6801 6892 (1994).
4. 42 U.S.C. section 6851 (1997).
5. ASHRAE Standards Committee. Ventilation for Acceptable Indoor Air Quality.
ASHRAE Publications, Atlanta, Georgia. ASHRAE 62 (1999).
6. ASHRAE Standards Committee. Ventilation for Acceptable Indoor Air Quality.
ASHRAE Publications, Atlanta, Georgia. ASHRAE 62 (2007).
7. ASHRAE Standards Committee. Ventilation for Acceptable Indoor Air Quality:
Guidance for the Establishment of Air Quality Criteria for the Indoor Environment.
ASHRAE Publications, Atlanta, Georgia. ASHRAE 62, Appendix C (1999), p. 17.
2
Investigation Plan
In 1984, the World Health Organization (WHO) suggested that up to 30 percent of all new and remodeled buildings worldwide experienced excessive
indoor air quality complaints.1 From 1989 to 1990, The National Institute
for Occupational Safety and Health (NIOSH) indoor air quality requests
jumped from 8 percent to 52 percent. In 1989, NIOSH completed approximately 500 indoor air quality investigations and concluded that 34 percent
of all sick building syndrome buildings were associated with indoor air
contaminants, outdoor air contaminants, building materials, or microbes.
Fifty-two percent of the buildings had inadequate ventilation, and 13 percent were “source unknown.”2 See Figure 2.1. It is not clear whether the
13 percent was due to an inability to identify unknown sources or due to
typical office building complaints encountered in all office buildings.
Although many environmental professionals have found a typical complaint rate in office buildings to be 8 percent to 12 percent, one publication
claims a normal dissatisfaction rate of 20 percent.3 Yet there is no fine line
between typical and abnormal.
The most typical complaints encountered in all buildings are that of temperature (too hot or too cold) and humidity extremes (too dry). Less common complaints are that of odors (e.g., cafeteria food in an executive’s office),
unwanted noise (e.g., copy machine operation), and inadequate lighting. In
other instances, complaints may be linked to job-related and occasionally
personal psychosocial stress (e.g., headaches) and poor ergonomic conditions. In a survey funded by the Environmental Protection Agency (EPA),
20 nonproblem buildings around the United States were surveyed in order
to develop a baseline of complaints in structures not identified as sick buildings. Data regarding specific complaints arising from buildings with “no
indoor air quality problems,” falling within the 20 percent normal dissatisfaction rate, was as follows:
•
•
•
•
Headache 19 percent
Eye irritation 16 percent
Fatigue 15 percent
Sinus congestion 12 percent
15
16
Indoor Air Quality: The Latest Sampling and Analytical Methods
Indoor Contaminants, 16%
Inadequate
Ventilation, 52%
Outdoor Contaminants, 10%
Building Materials, 4%
Microbial Contaminants, 5%
Unknown Sources, 13%
FIGURE 2.1
Source of complaints in buildings assessed by NIOSH study.
Sick building syndrome symptoms are very similar to buildings designated noncomplaint, nonproblem buildings. The difference is simply in the
number (or percentage) of complaints.
The greater “normal” is exceeded, the greater building-related sick building syndrome becomes a facility management concern. Clearly, when the
complaint rate in a 20-story office building exceeds 80 percent, there is a
problem. But what about complaints from 20 percent of the entire building
with 100 percent of the 15 occupants located within an isolated area of the
high rise complaining? What about a small office of 20 occupants with five
complaining?
Don’t rule out sudden events! Where symptoms occur immediately,
there has likely been an event or sudden release of a toxic substance into
an enclosed area. The release, occasionally referred to as the smoking gun,
may or may not involve an entire building. For example, a prankster released
mace into the air in a grocery store. Eye irritation and breathing difficulties with a sense of suffocation resulted in an evacuation of the entire store.
This scenario led to a series of events that culminated with carbon monoxide
exposures from the emergency response fire truck exhaust in front of the
store where the patrons and store employees gathered outside.
Poor indoor air quality and poor facility management response is a formula for disaster. Poor air quality spells poor employee moral, increased
sick days, and litigation. Many facility managers are becoming ever more
aware and wary of the need for good indoor air quality. In an Internet
publication:
According to a ground breaking Swedish study appearing in The
International Archives of Occupational and Environmental Health, 45%
of “so-called” sick building syndrome victims — treated in hospital
clinics — no longer have the capacity to work. Twenty percent of the sufferers are receiving disability pensions, 25% are “on the sick-list.”4
Although the truth behind the statement remains to be seen, media generated hysteria makes the article a reality. The cost of poor perceived or actual
indoor air quality by far outweighs the cost of a good, sound indoor air quality assessment!
Investigation Plan
17
An effective indoor air quality assessment involves a series of steps that
are outlined herein. Each step is a tool, and a tool is only as good as the
user. With knowledge and experience, some tools may not be necessary. The
investigator may choose to overlook some steps in one situation and follow
them in their entirety in another. For example, an investigation initiated by
complaints of headache and gasoline odors may require a couple of interviews and a building walk-through in order to locate possible sources of
gasoline. No two investigations are the same!
Documents Review
Obtain and review the building layout, mechanical blueprints (if available),
an inventory of activities, and an inventory of known chemicals, custodial
activities, and pesticide treatment activities. Additionally, some investigators
attempt to obtain full architectural plans, specifications, submittals, sheet
metal drawings, commissioning reports, adjusting and balancing reports,
inspection records, and operating manuals.
The building layout is a must have, particularly in public buildings. It may
be in blueprint form, or the schematic may be a fire exit plan. The latter is more
likely to be available and updated. As-built drawings are rarely kept up to date.
Mechanical blueprints for a building are rarely available, especially for
older buildings. If they are present, however, they are often outdated. This
document is one of the single most important documents the investigator
will require. An alternative backup is to have someone knowledgeable in
the mechanical operation of the building (e.g., building engineer or maintenance) sketch which air handler supplies what areas. This same person
should also be asked to update altered as-built drawings to the best of his or
her ability.
Identify each area by activity/activities. Get specific information. For
instance, activities may include word processing and filing carbonless copy
paper, legal casework, operating a blueprint copy machine, and gluing/
paste-up work. The facilities personnel may or may not be able to provide
this information. If not available, the activity information can be collected
during the actual walk-through.
An inventory of chemicals should be collected wherein the potential
for chemical exposures exists. In most public and institutional buildings,
chemical information is sketchy at best. Management may either generalize
substances as custodial cleaning fluid or copy toner, or they may be able to
provide material safety data sheets for all chemicals housed on the premises.
The latter is the least likely to occur.
Relevant to the investigator during the walk-through and while developing an air sampling strategy, custodial activities and schedules should be
18
Indoor Air Quality: The Latest Sampling and Analytical Methods
obtained along with the type of supplies used. This may take some research
on the behalf of the facilities manager or may require the investigator to
schedule interviews with the custodial personnel.
Custodial activities are an often overlooked contribution to indoor air
quality because custodial personnel generally operate after hours. Yet their
activities have been found to impact the indoor air quality significantly. In
one case, the custodial personnel used feather dusters in the office spaces
and emptied their vacuum waste while in the office spaces (and wearing a
paper respirator). In the morning, the office employees complained of visible
dust in the light streaming through the windows.
Pesticide treatment activities are generally out of sight and out of mind.
Although the scheduled peak treatment periods may coincide with complaints, the health effects of pesticides may be overlooked. In one case,
spraying for a cockroach infestation resulted in airborne allergenic parts and
pieces, a situation that could well have been avoided with roach motels.
Building a Walk-Through
The intent of the walk-through is to acquire an overview of the building and
occupant activities. A residential walk-through is considerably less complicated than one involving public buildings.
In public buildings, an initial walk-through should be planned and coordinated. Schedule the walk-through to include the occupancy periods and normal building operation. This accomplishes two things. It shows response to
and concern for the occupant complaints, and the building can be assessed
as it is when fully operational. The investigator is less likely to overlook relevant considerations during peak complaint periods.
In the interest of time, some investigators scale down the initial walkthrough considerably on the first visit by performing a documents review
and assessing questionnaires. With this information, the investigator can
then develop an air sampling strategy and complete the walk-through at a
later date while collecting air samples. Each investigator should be flexible
enough to revise the approach, as scenarios and conditions differ from one
investigative building to the next.
Occupied Areas
The investigator should have a set of floor plans (or a schematic) with all relevant information assessed during the documentation review. Several color
markers may be helpful along with a pen, paper, clipboard (or binder), and
flashlight. A building representative familiar with the air handling system
Investigation Plan
19
should accompany the investigator with a set of keys and tools, and a ladder
should be accessible as well.
The general condition of the occupied spaces in a building should be
assessed. Some items to look for include, but are not limited to, the following:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Odors
Lint or soiling on carpets
Dirt on sheet vinyl and floor tiles
Dust on surfaces (e.g., desks and ledges)
Water damage stains (e.g., ceiling tiles with tealike stains)
Suspended dust in air (e.g., observed in light)
Moisture collecting on surfaces (e.g., condensation on windows)
Dirt and debris around the air diffusers
Cloth versus vinyl upholstery
Presence of homeowner air purifiers
Cleanliness of kitchen/food areas
Rotting food in office spaces and trash receptacles
Presence of plants
Wall penetrations
Peeling paint and vinyl wallpaper
Storage of chemicals
Continue to add to the list as the situation dictates. Always keep in mind, “If
it looks out of place, it probably is!” Ignoring this old adage could culminate
in an oversight. Even if an unexplained sense of something not right should
occur, attempt to identify the reason.
Air Handling System
An investigation of the air handling system generally requires some basic
knowledge beyond the scope of this book. Such an assessment may require
the assistance of a mechanical engineer or an industrial hygienist knowledgeable in HVAC systems.
Although the investigator may not be knowledgeable, air handling systems are one of the single most important contributors or solutions to indoor
air quality problems. Some of the more basic items to look for in a centralized
air handling unit include:
• Rust, damage, and water leaks around the exterior of the units
• Condition and amount of water in the drip pans
20
Indoor Air Quality: The Latest Sampling and Analytical Methods
• Appearance of a slime or fuzzy growth in or around the air handling unit and duct
• Condition of air filters
• Filter exchange schedule logs
• Adequate fresh air intake
• Dirt, damage, and moisture buildup
• Tools and equipment stored in an air handling unit
Between the main air handling units and the occupied spaces, many systems
will have additional conditioning/reconditioning units. As they are generally in the ceiling spaces, these units are a little more difficult to access and
will require a ladder.
In the occupied spaces, the air supply should be measured and assessed
as compared to the specifications. In some instances, building occupants
damped down their air supply vents. These same individuals will often be
the ones complaining the most about poor indoor air quality. Sometimes
occupants get creative and jury-rig a cardboard diverter so the air will not
blow directly onto them. In the absence of air supply measuring equipment,
the investigator should minimally observe and take notes.
In cases requiring negative or positive pressure in a building, pressure
differential should be measured. Once again this may require some outside assistance. In hospitals, operating rooms require positive pressure, and
tuberculosis patient rooms require negative pressure. In buildings with
considerable infusion of outside air through the wall spaces, investigators
deeply entrenched in mold remediation are finding that delivery of positive
pressure alleviates the mold problem considerably. Thus, positive/negative
pressure measurements may be beneficial in some instances. For more details
regarding HVAC systems, see Chapter 16.
Bathroom Air Exhaust
Bathrooms have their own exhausts, and they are frequently poorly maintained. Sometimes the exhaust fan has ceased to function, the exhaust vent
has been closed, or the vents are covered with debris. When the bathroom
exhaust is associated with poor indoor air quality, building occupants may
comment, “The air smells like a toilet.” In some instances, the exhaust air
from the bathrooms gets captured and entrained in the building air supply
system, or the bathroom air is drawn out into the hallways and vicinity of
the bathrooms where the bathrooms are not adequately exhausted.
A quick, easy method to inspect the bathroom exhausts is to observe
movement of dust on vents or to hold toilet tissue to the vent. Observe the
direction of movement. If the tissue hangs down, it is a safe bet that the air is
not being exhausted. Or if air exhaust blows into the room instead of being
Investigation Plan
21
actually exhausted, the blower was probably installed improperly. Poor
design and installation is more common than one would like to believe.
Sewer System
Leaks in sewer systems are more difficult to address than simply tracking sewer odors back to a bathroom. Odors can emanate from the most
obscure, elusive areas of a house and sewer gases may be overlooked for
lack of knowledge for a simple how-to investigate migrating sewer odors,
see Chapter 17.
Occupant Activities
Observe special activities within a building, ordinary and out of the ordinary. Beyond the facilities personnel interviews, the investigator may observe
activities that were not brought up in the discussion. This may involve renovation projects, or commercial and industrial activities. The investigator
should become familiar with all activities being conducted in the building
and then determine chemical usage, direction of air movement, and local
exhaust locations.
Interviews with Facilities Personnel
During the walk-through, the maintenance and custodial personnel should
be interviewed. Keep records of all these conversations. Information that
may not seem relevant at the time may become important later.
Maintenance Staff
The maintenance worker that is most familiar with the air handling system
should be interviewed. In smaller facilities, this may be one individual who
manages everything from nasty toilet odors and bats to complex electrical
problems. In the larger facilities, someone may be dedicated to HVAC management. Whichever is the case, seek assistance from the person most knowledgeable in the system and obtain the following information:
• Location of fresh air intake, local exhaust units, bathroom vents, and
cooling tower(s) (if not indicated on the blueprints/floor plans)
• Placement of air filters (e.g., air handling unit or air return grid)
• Frequency of filter changes in the air handling system
22
Indoor Air Quality: The Latest Sampling and Analytical Methods
• Special problems with the units
• Rationale and usage of air deodorants and biocides in the air handling system
• Typical occupant complaints and maintenance response
• Chemicals used frequently and associated health effects
• Location of stored chemicals
• Management of hazardous materials and/or waste
• Methods and associated complaints when accessing work above
ceiling tiles
• Recent renovation or construction activities
• Methods and schedule for pesticide control
Although a wealthy resource of information, maintenance personnel have a
tendency to be overlooked all too often. Give them the opportunity to voice
their impressions and special observations that may be relevant to the investigation. This encourages cooperation and participation of behind-the-scene
contributors, and there may be some enlightened information that would
otherwise have been unacknowledged.
Custodial Staff
Another overlooked contributor to the indoor air quality is the custodial
staff, which is out of sight, out of mind. However, custodial activities can
greatly impact the air quality of the building. Be forewarned that many are
on contract and have a tendency to feel defensive when queried as to their
activities. You may find someone who speaks impeccable English lapse into,
“I don’t speak English.” The custodial staff interview should include:
•
•
•
•
•
•
•
•
Cleaning schedule for the various areas
Type of vacuum cleaner
Frequency and thoroughness of vacuuming
Location where the vacuum bags are changed or contents dumped
Dusting procedures, frequency, and thoroughness
Chemicals used frequently and associated health effects
Location of stored chemicals
Waste management procedures and frequency
Encourage further input of information and avoid criticizing their procedures. The investigator’s purpose is to collect information. Recommended
procedural changes can come at a later date.
Investigation Plan
23
Observation of Surrounding Areas
Observe activities outside the building. Traffic movement and peak road
usage periods may impact the indoor air quality. Identify areas where automobile, truck, and forklift exhausts may enter the building. The building
air intake or wall penetrations might be so located that vehicular exhaust
contributes to the indoor air quality.
Roof and road asphalting are generally associated with building complaints. Proximity to the fresh air intake should be considered, and information regarding the approximate time of day and duration of the hot as phalt
operation should be noted.
Take note of industrial and commercial activities, the location of exhaust
stacks, apparent visible emissions, and type of industry or commercial activity. Suspect air contaminants can sometimes be associated with known predicable environmental contribution by industry type. For instance, a common
contributor in commercially zoned areas may be naphtha from a dry cleaning operation.
Whenever outside air is suspect, note prevailing wind direction, the relative location of the building fresh air intake, suspect point sources, and
exhaust stacks. Observe all possible mechanical and environmental conditions that may exasperate or contribute to the health complaints within the
building.
Assessing Occupant Complaints
The reason for an indoor air quality investigation is occupant complaints.
Complaints are either ongoing or the focus of a baseline study. For this reason, an assessment of occupant complaints is the most important consideration when conducting a preliminary building investigation.
As individual health complaints can be biased and ambiguous, some investigators choose to perform interviews only. Yet interviews can be unwieldy
in office buildings with high occupancy. Thus, in high-occupancy buildings,
the investigator should both administer questionnaires and conduct limited
interviews. Follow all questionnaires with random interviews or with interviews of select respondents.
Upon completion of the questionnaires and interviews, the purpose is to
isolate, identify, and define complaint and noncomplaint areas. Noncomplaint
areas are frequently overlooked by many investigators, but confirmation and
clarification of these areas is important for comparison air sampling.
24
Indoor Air Quality: The Latest Sampling and Analytical Methods
Questionnaires
Indoor air quality questionnaires should be designed to minimize bias, maximize the response rate, and provide information that is useful to the investigator. This is a tall order, not easy to fill.
Types of Questionnaires
As the questionnaire is to be filled out by a biased building occupant, bias is
impossible to eliminate entirely. The lingering question remains, “How do I
minimize bias?” There is no consensus in the response.
EPA and NIOSH published a one-page, open-ended questionnaire and an
occupant interview form. Responses to such a questionnaire may be as brief
as, “I’m always sick” or “My doctor says I have sick building syndrome,” or
it may include extensive details. When crunching numbers and assessing
open-ended questionnaires, the investigator will often encounter difficulties
weighing the responses.
Some investigators have developed their own questionnaires with a listing
of specific complaints. Others develop these questionnaires with a response
scale (e.g., always, often, sometimes, or rarely). Opponents to this approach
state that symptom labels can be interpreted differently. For instance, one
person may interpret shortness of breath to mean slow, labored breathing
while another may feel it means rapid, shallow breathing. One way around
this is to define or clarify some of the symptoms. Leave space for and encourage comments and observations. It is surprising the information an investigator might glean from offered information.
Questionnaire Response Rate
A 100 percent questionnaire-response rate is a pipe dream. No matter how
well-designed a questionnaire, there will be some that just refuse to or are
unavailable to complete a questionnaire. In marketing surveys, a 20 percent
response rate is considered good, but this is unacceptable in indoor air quality investigations. An effort should be made to get a minimum of 80 percent
return. It is possible!
To better design a questionnaire, the reasons for failure to respond should
be taken into consideration. Some of the reasons for not responding include:
•
•
•
•
•
Too time-consuming
Too difficult to read
Never received it
Not present for the duration of the survey (e.g., out of office)
Lost it
Investigation Plan
25
• Didn’t remember to turn it in
• No complaints
• Fear of management reprisals
Each one of the above issues can be overcome. Create a one-page, easy-toread form with check boxes and comment space for each section either on the
front page or on the back of the one-page questionnaire.
Color-code the questionnaires on the basis of air handling unit zones. This
serves a dual purpose. First, colored paper is harder to lose on a desktop of
all-white paper. Second, organizing the questionnaires is easier when they
have been color-coded.
Give the occupants enough time to fill out the questionnaires, but not so
much time as to allow them to forget or lose it. In offices where occupants
frequently work outside the office, a week is generally enough time. In offices
where occupants are present the entire day, a couple of hours may be sufficient. The timing should be worked out with management.
Either on a cover sheet or in the heading of the questionnaire explain the
rationale for the questionnaire and the importance of having noncomplaint
respondents along with the others. The information may also be made confidential between the consultant and the occupant.
Provide a time and location for the completed questionnaires. This should
be attainable and in close proximity to where the occupant is located or
departs the building.
Informational Data
A well-written questionnaire can provide important or potentially informative information to the investigator. The components may include, but not be
limited to, the following:
•
•
•
•
•
•
•
Physical location in the building
Comfort level (e.g., perceived temperature and humidity)
Odors
Health concerns thought to be associated with the building
Onset of symptoms (e.g., approximated date)
Occurrence of symptoms (e.g., early morning on a Monday)
Pre-existing conditions that might be more adversely impacted by
exposures while in the building
• Occurrence of symptom relief (e.g., two hours after leaving work)
• Observed unusual/suspicious activities or events
26
Indoor Air Quality: The Latest Sampling and Analytical Methods
As data is more easily assessed relative to complaint areas, physical location
is a must. If reluctant to fill in this information, the respondent should be
reminded of its importance and, at a minimum, provide the general area. Yet
area generalities are often inadequate and difficult to pin down. In the same
light, people who tend to not stay put in an office environment are difficult to
assess. Generalities make the final assessment quite challenging.
Comfort level allows the respondent to complain without associated temperature and humidity concerns with health complaints. They are not one
and the same, but comfort level may enhance or reduce perceived health
problems.
Odors are very subjective. Heavy perfume to one may be an overpowering stink to another. The smell of asphalt may be described by one person as
sweet and by another as a chemical smell. The latter description is common
for unfamiliar odors. Whereas most people describe mold by-products as
mildew, others describe it as dirty feet or like the interior of a cave. While it is
difficult to interpret odor descriptions, the information can assist the inspector to glean direction as to the potential source of health complaints.
The actual health complaints should be associated with the building, not outside activities. If providing a checklist format, offer symptoms that are easy to
interpret. For instance, the symptom of congestion may be replaced with stuffy
nose. Irritated skin may be replaced with dry, flaky skin or itchy, red bumps. In a
listing, try to keep the description of symptoms abbreviated and to the point.
The date of onset of symptoms is difficult if not impossible to tie down.
Unless they experience health effects the first time they walked into the
building, people do not notice they are having health problems until long
after the initial exposures. Then most of the occupants will live with it until
they hear others expressing concerns. On the other hand, if an approximate
time period can be associated with occupant activities, building renovation,
or scheduled work activities (e.g., pesticide application), a narrowing of the
gap on source identification may occur.
Pre-existing health conditions or medications that might be adversely
impacted by exposures in the building may or may not be understood by the
respondent, but they can occasionally provide some valuable insights. For
instance, someone who has anemia would be more susceptible to the health
effects of carbon monoxide that others. Asthmatics will experience worsened
conditions when exposed to excessive airborne allergens (e.g., dust mites).
In most indoor air quality situations involving allergens in a building,
the occupant will experience relief within two hours of departure. If the
exposure is to carbon monoxide, relief may not be apparent for a couple days.
This information can be very helpful to the investigator.
Permit the occupant some space to speculate and provide personal insight as
to the source of the problem. Occasionally, occupant observations provide tremendous insight. It has been to the amazement of the author that people given
a chance to contribute, unbeknownst to them, had the answer all along.
Investigation Plan
27
Interviews
When not used as the only means for gathering complaint information,
interviews are where the investigator can clarify information and gain further details not obtained from the questionnaires. Unless you have a preconceived concern or special issue, allow the interviewees to tell you in their
own words about their concerns. Concern is a less intimidating term than
complaints. Listen to what they say without a preconceived notion, and follow up with questions to get a clear focus on that individual’s concerns. If not
already covered, all the items discussed above should be discussed as well.
Yet, a touch of reality, some interviewees will gladly talk all day. Set a time
limit and at some point politely move on.
Summary
Steps include a documents review, building walk-through, interview of facilities personnel, observation of the surrounding areas, and an assessment of
occupant complaints. All steps may or may not be required in each different
situation, and the components are subject to change likewise.
Keep in mind that the procedures presented herein can and should be
expanded or utilized in part. When performing a preliminary investigation,
attempt to avoid preconceived notions and biases. Be prepared to seek that
which is intuited. An open mind is the investigator’s greatest tool.
References
1. U.S. Environmental Protection Agency. Indoor Air Facts No. 4 (revised) Sick
Building Syndrome. Indoor Air Quality, EPA (April 26, 2010).
2. Hedge, A. Addressing the Psychological Aspects of Indoor Air Quality (Paper).
Cornell University, Ithaca, New York (1996).
3. U.S. Environmental Protection Agency and National Institute for Occupa­
tional Safety and Health. Building Air Quality: A Guide for Building Owners
and Facility Managers. U.S. Government Printing Office, Washington, D.C.
(December 1991).
4. Goldstein, R. Sick Building Syndrome: Floods, Mold, Cancer, and the Politics of Public
Health. Organic Consumers Association. Retrieved from http://www.organicconsumers.org/articles/article_17435.cfm (May 12, 2010).
3
The Hypothesis
The objective of an investigator is to identify and solve indoor air quality
complaints in a way that prevents a recurrence, not create other problems.
Although this may seem an overstatement of the obvious, poorly researched
and executed investigations are consistently recurring.
In one situation, an investigator recommended increased fresh air intake.
Health complaints from the occupants were reduced from 90 percent to
20 percent. Another investigator convinced the building management that
the 20 percent could be improved with a building “burn out.” The source of
the complaints had never been identified, but the second investigator, without further investigation, recommended a procedure that worked in another
building. Sounds good! It should work again. The burn out involved elevating temperatures over a long weekend and flushing the building with
100 percent makeup air. The result was 75 percent health complaints, a recurrence of problems.
Another situation involved elevated mold spores and no diagnostic
evaluation to determine the source of amplification. The investigator
speculated that the spores were growing in the perpetually damp building crawl space. The recommendation was to use powerful exhaust fans
to move air through the crawl space and dry out the soil. The result was
air movement over the soil and being exhausted outside where it was
picked up by the air intake and distributed throughout the building.
Health complaints worsened. The reason was an untested hypothesis,
insufficient diagnostic sampling, and recommendations based on unsubstantiated speculation.
A well-researched preliminary investigation is the best avenue to avoid
some of these pitfalls. A strong foundation of information should result in
a hypothesis. Avoid assumptions! Gather information, formulate a hypothesis, test the hypothesis, and make recommendations. The preliminary
investigative process was discussed in the preceding chapter. Herein we discuss putting the information in an easy-to-assess format and formulating a
hypothesis.
29
30
Indoor Air Quality: The Latest Sampling and Analytical Methods
Information Review
An easy-to-access format of the voluminous amount of data possible in performing an indoor air quality investigation can be daunting at best. The
author has reviewed many different formats and found an approach that
works best in most instances. The methods provided are simplified and
should be expanded to suit individual needs. These assessment methods are
a working tool to be expanded and improved upon.
Building Assessment
The building assessment includes information gathered from the building walk-through, interviews of facilities personnel, and observations of
surrounding areas. If not simplified, the information may become a paper
morass, overwhelming and confusing.
One suggested approach wherever possible is to summarize information on
the building blueprint or schematic. This may even be the ever-present fire evacuation plan. Either take notes on the drawing during the walk-through or summarize important information on the drawing after compiling all the data. In
a publication regarding building assessment methods, “Building Air Quality,”
NIOSH/EPA suggest this technique for assessing pollutant pathways.1
Color markers, colored pens, overlays with indelible markers, and a coding system are recommended tools. Several sheets of the basic floor plans
are also helpful. Summary comments may include, but are not be limited to,
the following:
• Air delivery zones, based on air handling units supplying air to
that zone
• Plumbing discrepancies (e.g., leaking pipes)
• Ventilation discrepancies (e.g., air supply vent closed) or observations (e.g., redirected air flow)
• Unspoken comments or fixtures regarding perceived air quality
(e.g., air purifiers and pedestal fans)
• Chemical storage areas
• Location and type of equipment that may involve air contaminants
(e.g., copy machine)
• Water damaged structural components (e.g., water damaged ceiling tiles)
• Lifting/poorly adhered floor tiles and sheet vinyl
• Peeling paint and vinyl wallpaper
• Rusted metal structural components (e.g., air vents and window
frames)
The Hypothesis
•
•
•
•
•
•
•
•
•
•
•
•
•
•
31
Room(s) with carpeting
Stains of flooring (e.g., burned floor tiles or stained carpeting)
Bathroom exhaust discrepancies
Location of elevators and other structures that may impact air movement (e.g., doors and stairwells)
Plants
Wall penetrations
Areas where investigator, not occupants, noticed odors
Location of bathrooms and custodial closets
Commercial/industrial activities in the building
Approximate direction of commercial/industrial activities outside
the building
Direction of prevailing winds
Location of break room/kitchen
Signs of infestations (e.g., cockroaches, rodents, bats, pigeons)
Local exhaust ventilation
Comment about and enter information that does not seem relevant at the
time. When assessing the relative locations of potential sources, discrepancies, and other observations as one, the investigator may be able to relate one
previously disassociated item to another. See Figure 3.1.
Complaint Occupant
The single most important source of information is the occupant. With building complaint input, the investigator can define the complaint area(s) and determine the severity of the complaints as well as look for symptoms, occurrence
of symptoms, and perceived associations. Problem and nonproblem areas can
be identified. Problem areas may be compared to the building assessment findings, and a potential causative agent can be projected. There is just one factor
that complicates the process: buildings with a large number of occupants.
In a large-occupancy building, the investigator must collect a large volume
of information and reduce it to a manageable format. Color-coding questionnaires (e.g., coded air handling zones) is a good start. For confidentiality,
each set should also be numbered, summarized, and filed by the investigator. The numbered and summarized information may then be installed into
a spreadsheet or color-coded on the floor plans. It is best to make entries in
both areas, and clarity is more apt to be gleaned from specific sites occupied
by each of the respondents. Where there are no cubicle or office numbers,
a little more creative coordination is required. For an example of the summary format, see Figure 3.2.
34
Indoor Air Quality: The Latest Sampling and Analytical Methods
Upon completion of the complaint summary or interviews, the investigator should attempt to relate the symptoms to potential sources. This may
involve a direct correlation, or the possibilities may be multiple.
In most sick building syndrome situations, the symptoms are allergenic in
nature (Appendix A) and occur only when the occupant is in the building
and subside within a couple hours after departure from the building. As the
recent trend has been to point an accusatory finger at molds, the full range of
possibilities is frequently overlooked.
To a lesser extent there are those sick building syndrome cases beyond
the norm that involve a wider range of health effects (e.g., disease, febrile,
flu-like symptoms, dermatitis, irritation, and systemic toxicity). These nonallergy health effects may be associated with a single substance, or they may
be complicated by the effect of several substances. Several different agents
may have the same health effect and result in an accumulation of different
low-level exposures, or they may have different health effects contributing
to the overall impact. For reference information concerning health effects,
causative agents, and their occurrence, see Table 3.1.
Hypothesis Development
With the completed building and complaint assessments, the investigator
can project possible scenarios of cause and effect. Write down all probable
explanations for the complaints. Look at the noncomplaint areas as well as
the complaint areas. Look for links between the building components and
complaints. Project sources of exposure and pathways.
One area may have several sources that may contribute to the overall
health complaints. For instance, a carpet infested with dust mites and air
supply vents disbursing mold spores may result in allergy symptoms. If the
investigator theorizes only the mold spores, encounters moderate airborne
exposures, and remediates the air supply vents, the contributing dust mites
will be missed and remain uncorrected with a level of continued allergy
symptoms.
On the other hand, different areas of one building may have different
problems and each of these as complex as that discussed previously. Area 1
may have rodent allergens and airborne fiberglass from the air duct lining,
and Area 2 may have leaking (e.g., chlorofluorocarbons) and excessive levels
of carbon monoxide. Symptoms will be different in these areas. If considered
part of a composite, the two areas will be overlooked as one. The cause and
effect may be overlooked entirely.
These scenarios are not unusual. The investigator should keep an open
mind at all times. Develop a set of hypotheses. Consider the pathways and
test the hypotheses.
The Hypothesis
35
TABLE 3.1
Reference Chapters for Relating Symptoms and Source Occurrence
Allergy symptoms: associated with the building and symptoms subside within a couple
hours of departure
Chapter 4
“Pollen and Spore Allergens”
Chapter 5
“Viable Microbial Allergens”
Chapter 14 “Forensics of Dust”
Chapter 15 “Animal Allergenic Dust”
Disease: associated with a building and symptoms continue until the illness has run its course
Chapter 6
“Pathogenic Microbes”
Dermatitis: associated with the building or a work product, and symptoms may improve
upon removal or departure from the area but recovery may take a few days
Chapter 4
“Pollen and Spore Allergens”
Chapter 5
“Viable Microbial Allergens”
Chapter 6
“Pathogenic Microbes”
Chapter 7
“Toxigenic Microbes”
Chapter 8
“Volatile Organic Compounds”
Chapter 12 “Formaldehyde”
Chapter 14 “Forensics of Dust”
Chapter 15 “Animal Allergenic Dust”
Eye irritation: associated with the building and subsides upon departure
Chapter 4
“Pollen and Spore Allergens”
Chapter 5
“Viable Microbial Allergens”
Chapter 7
“Toxigenic Microbes”
Chapter 8
“Volatile Organic Compounds”
Chapter 9
“Mold Volatile Organic Compounds and Mold Detection”
Chapter 12 “Formaldehyde”
Chapter 14 “Forensics of Dust”
Chapter 15 “Animal Allergenic Dust”
Systemic illness: associated with the building and may subside over time after departure
Chapter 5
“Viable Microbial Allergens”
Chapter 7
“Toxigenic Microbes”
Chapter 8
“Volatile Organic Compounds”
Chapter 9
“Mold Volatile Organic Compounds and Mold Detection”
Chapter 12 “Formaldehyde”
Chapter 14 “Forensics of Dust”
There are two ways to test a hypothesis. The easiest way is to project the
source and associated solution. Where a hypothesis projects an inexpensive solution and sampling is expensive, the hypothesis may be tested by
manipulating building conditions or the ventilation system. As indicated in
Figure 2.1 in Chapter 2, the source of complaints in many indoor air quality
36
Indoor Air Quality: The Latest Sampling and Analytical Methods
investigations had been identified in 52 percent of the study cases as inadequate ventilation. It would be more appropriate to state that ventilation rectified the problem, not that it was the problem.
Sampling is a more direct approach to proving a hypothesis, and is the
only method whereby the investigator can definitively clarify the source or
sources of occupant complaints. As with a medical doctor who develops a
hypothesis as to an illness, the only way he can definitively prove the cause
of the illness is to perform a series of tests. To properly treat an illness the
doctor must identify the appropriate tests that will provide the much needed
information. If the diagnosis is incorrect, treatment of symptoms may or may
not work. It is, likewise, preferable in indoor air quality that the hypothesis
be tested, proven, and acted upon appropriately.
The Proactive Approach
In order to minimize the sampling and effectively target potential sources
of indoor air quality complaints, the investigator would be best served by
having performed a baseline walk-through of the same building when there
were no complaints. The recently published ANSI/ASHRAE Standard 189.1
requires postconstruction air monitoring and an ongoing means to assess
indoor air quality complaints.
A proactive survey involves a scaled down variation of the more in-depth
investigation that results from health complaints. The upfront costs are
greater, but the end result pays off in dividends.
Develop a plan for preventing poor air quality. This plan should include,
but not be limited to, the following:
• A means whereby complaints are addressed in a timely fashion
• A guide for determination of an excessive number of complaints in a
building or area of a building
• A means for maintaining records of building complaints, activities,
and renovations
• A response action
Establish a baseline of occupant concerns and a building profile. A baseline
taken in a healthy building will provide valuable information should the
facilities manager or investigator determine that the building has an inordinately high number of health complaints.
Perform a limited amount of air sampling. This should be kept at a minimum while providing data regarding contaminants that may be reasonably
implicated in future concerns.
The Hypothesis
37
Steps include a walk-through of a facility, an assessment of occupant complaints, identifying problem niches, assessing the building, assessing activities associated with the building, and compilation of all the data. Making
sense of the mass of information collected is the investigator’s greatest
challenge.
Beyond the Scope
There are literally hundreds and thousands of substances that go beyond
the scope of a single textbook. Other areas of expertise that may be requi­
red include medical physicians, industrial hygienists, toxicologists, and
psychiatrists.
Medical Physicians
Medical physicians can address special situations involving individuals
that are particularly susceptible to various environmental agents, and they
can perform some speculative testing of occupants to determine susceptibi­
lity. Some examples are of susceptible individuals are immune-suppressed
patients, individuals that are anemic, and asthmatics. The boy that lived in
a bubble had no immune system to speak of. Were he to be exposed to the
same environment as others he would surely die.
Prescription and over-the-counter drugs can also affect one’s reaction to
environmental influences. If while taking an allergy medication that causes
one to become drowsy an individual is exposed to low levels of a chemical
narcotic, the effect can be enhanced.
Speculative testing is not the ideal approach to indoor air quality situations, but it is applicable in some situations, particularly where there are
no known environmental sampling methods readily available for testing
a hypothesis. In a hospital, a group of people experienced allergy symptoms when working in an area where latex gloves were frequently changed.
Upon performing latex allergy testing on some of the people, the physician
was able to confirm latex sensitivities in those with the greatest number of
complaints.
Occasionally, a person claiming to have multiple chemical sensitivity may
be one of the building occupants. The mere uncapping of a magic marker will
elicit a reaction. Perfumes and deodorants are intolerable. They cannot go to
a gasoline station for fuel without special respirators. If one of these individuals is a respondent to an indoor air quality questionnaire, the response will
likely be dissimilar to the others. Generally, these people will have sought
diagnosis by a physician.
38
Indoor Air Quality: The Latest Sampling and Analytical Methods
Industrial Hygienists and Toxicologists
Industrial hygienists are trained and experienced in the anticipation, recognition, evaluation, and control of health hazards. Some of the less frequently
encountered indoor air quality issues involve substances that are beyond the
abilities of an untrained individual to assess. These substances include metals and pesticides/insecticides.
Some of the metal exposures that may be considered in indoor air quality
are airborne lead, mercury, and arsenic. This may appear simple on direct
analysis, but an assessment must be made on the basis of the form a metal
is in and the environment. For example, Scopulariopsis bevicaulis growing
on wet copper arsenite pigment wallpaper will produce trimethoxy arsenic vapor. Arsine gas is evolved when arsenic compounds react with acids.2
These different forms of arsenic would require different sampling methodologies, and this applies likewise to the other metals.
Misapplied pesticides can have adverse, sometimes life threatening effects
on individuals. One of the most commonly sampled pesticides indoors is
the banned termiticide chlordane. Although banned from use in the United
States, DDT is still encountered in the environment and continues to be used
in Third World countries.
Industrial hygienists and toxicologists stay current with publications on
recent findings in research that is not covered by the media. Of import to
indoor air quality is a recent hazard review on carbonless copy paper. It was
found that some types of carbonless copy paper result in symptoms of skin,
eye, and respiratory tract irritation; allergic contact dermatitis; and some
unclear systemic reactions. Although the chemical agent has yet to be identified, the relationship was indicated through epidemiological studies.
In another case, occupants complaining of dermatitis on the back of their
thighs all sit on fabric upholstered chairs. The chairs are found to be allergen
free. Yet it is noted that custodial staff members use a strong disinfectant for
cleaning the chairs. This is a case of guilt by association.
Psychiatrists
This is the skeptic’s corner, the last recourse for finding the cause of sick building syndrome. As cases go unsolved, investigators turn more and more to perceived indoor air quality on the basis of physical, psychological discomfort,
and odors. Then, too, there is mass psychogenic illness (MPI), or mass hysteria.
Mass psychogenic illness refers to “the collective occurrence of a set of
physical symptoms and related beliefs among two or more individuals
in the absence of any identifiable (cause).” Social psychological processes
of contagion, where complaints and symptoms spread from person to
person, and convergence, where groups of people develop similar symptoms at about the same time ... Environmental events, like an unpleasant
odor, can trigger contagion and convergence processes, and occupants
The Hypothesis
39
who cannot readily identify what has triggered their symptoms often
attribute these to any visible environmental changes, such as installation
of a new carpet, or invisible agents, such as “mystery bugs.” MPI symptoms include headache, nausea, weakness, dizziness, sleepiness, hyperventilation, fainting, and vomiting, and occasionally skin disorders and
burning sensations in the throat and eyes.3
Summary
Upon completion of a preliminary investigation, the information should
be compiled and simplified. Otherwise, the investigator may become overwhelmed and may not be able to see the forest through the trees.
The building and occupant assessments should be critically reviewed and
a hypothesis developed. The hypothesis may involve one or several potential
sources, and it may be complicated by the existence of one or several disassociated areas. Too often this point is overlooked. Recommendations to remediate
one of several problems may result in unsatisfactory results. The objective is to
open the door to all possibilities, to limit the amount of testing required to prove
a hypothesis, and to appropriately target identifiable, quantifiable sources.
The most direct approach to proving a hypothesis is sampling. Sampling
may involve one, or a combination of, screening, air sampling, and diagnostic
tests. Yet even the testing may result in incomplete, inconclusive information
if not performed properly. There have been instances whereby an untrained,
uninformed investigator has taken expensive samples where strategy was
not considered, sampling methodologies were inappropriate, and interpretation was limited. It is the purpose of this book to provide direction for
sampling some of the more commonly encountered substances in sick building syndrome. See Table 3.1 for suggested chapters for directions to making
sampling decisions.
References
1. U.S. Environmental Protection Agency and National Institute for Occupational
Safety and Health. Building Air Quality: A Guide for Building Owners and Facility
Managers. U.S. Government Printing Office, Washington, DC (Dec. 1991), p. 70.
2. Kaye, B.H. Science and the Detective. VCH, New York (1995), p. 9.
3. Hedge, A. Addressing the Psychological Aspects of Indoor Air Quality (Paper).
Cornell University, Ithaca, New York (1996), p. 3.
Section II
Omnipresent Bioaerosols
4
Pollen and Spore Allergens
They are everywhere! Except in the most restrictive of environments (e.g., an
environmentally controlled, filtered bubble enclosure), allergens are everywhere, and the most commonly recognized allergens are pollen grains and
fungal spores.
Pollen grains are the male reproductive cells that are dispersed by plants
to fertilize the female flower of the species. They are typically outdoor allergens but have on occasion been found to be problematic due to the capture
and retention of the pollen within an air system.
Spores, as presented herein, are to include all forms of fungal spores (e.g.,
mold spores and mushroom basidiospores). Fungal spores are reported to
affect more than 20 percent of the adult population. It should be noted, however, that some bacteria may also produce spores, and these are discussed
more fully in Chapter 5.
Pollen grains and spores must be airborne in order to cause respiratory
allergy symptoms, and the total exposure to all of these will have a varying
affect on those exposed. The higher the exposures, the greater the number
of people affected. Their impact is irrespective of viability, or their ability to
grow. Dead molds do not go away. They merely stop reproducing and growing. Mold spores persist—dead or alive!
Occurrence of Pollen and Spore Allergens
Pollen grains are the male reproductive cells that are dispersed by plants
and carried by insects, animals, and wind to fertilize the female flower of
like species. Those that are carried by insects and animals tend to be sticky,
possess an elaborate exterior surface (e.g., spines and heavy ridges), and are
large by comparison to the other pollen grains (e.g., up to 250 microns in
size). On the other hand, those that are dispersed by wind tend to be nonsticky, smooth, light in density, and small in size (e.g., generally less than
50 microns). These reproductive cells are produced by weeds, grasses, and
trees. There are more than 350,000 species of plants. Plants are geographic
and pollen production (i.e., pollination) is seasonal.
Fungi include single celled yeasts, filamentous molds, and multicellular
mushrooms. Possessing a hard chitin or polysaccharide exterior covering,
43
44
Indoor Air Quality: The Latest Sampling and Analytical Methods
fungal spores are typically resistant to drying, heat, freezing, and some
chemical agents.
General Information
Allergenic spores and pollen may be transported by high winds as far as
1500 miles, and it is possible to find them 100 miles from their point of origin.1 If one were to draw a contour map showing levels at various points
from a source, it would be evident the highest concentrations are close to the
source, diminishing with distance and impacted by wind direction, velocity,
and volume of pollen produced at the source.
Small fungal colonies may discharge as many as 30 billion spores per day.
Pollen grain discharges may be likewise remarkable with numbers reported
as high as seven trillion pollen grains per tree on a season. See Table 4.1.
Attempts have been made to identify allergenic pollen types and the times
of the year when their local presence is increased. Some highly allergenic
individuals make decisions for relocation based on the prevalence of given
allergens. Although Table 4.2 demonstrates an effort to categorize by state,
the determinations are generalized and may not be representative of local
areas within the regions mentioned.
The size, shape, and density of the airborne allergens affect their aerodynamic properties, while the air humidity, wind direction, wind velocity, and obstructions affect their travel path as well as their travel distance.
Temperature, soil types, and altitude may also impact the quantity of airborne allergens.
The size of fungal spores range from 1 to more than 500 microns in diameter/
length, but those that are typically airborne range in size from 1 to 60 microns.
TABLE 4.1
Pollen and Spore Single Source Discharge Rates
Fungal Spores—One Colony or Growth Unit
Ganodenma applanatum
Daldinia concentrica
Penicillium spp.
30 billion per day
100 million per day
400 million per day
Pollen Grains—One Tree
European beech (Fagus sylvaticus)
Sessile oak (Quercus petraea)
Spruce (Picea abies)
Scotch pine (Pinus sylvestris)
Alder (Alnus spp.)
409,000,000 per year
654,400,000 per year
5,480,600,000 per year
6,442,200,000 per year
7,239,300,000 per year
Source: From Smith, E.G. Sampling and Identifying Allergenic Pollens
and Molds: An Illustrated Identification Manual for Air Samplers.
Blewstone Press, San Antonio, Texas (1990). With permisson.
Pollen and Spore Allergens
TABLE 4.2
Plant Allergens by Region
Northern Woodland
Trees (April–June)—birch
Fungi (June–October)—mushrooms and puffballs; watertight cabins and cottages tend to be
moldy
Eastern Agricultural
Trees (March–May)—ash, birch, box elder, elm, mulberry, oak, sycamore, and walnut
Grass (May–July)
Weeds (July–September)—hemp, goosefoot, and ragweed
Fungi (May–November)
Other—castor beans, cottonseed, and soybeans
Southeastern Coastal
Trees (February–April)—ash, elm, oak, pecan, and sycamore
Grass (February–October)
Weeds (July–October)—ragweed
Fungi (all year)
Southern Florida
Trees (January–April)—oak
Grass (January–October)
Weeds (June–October)—ragweed
Fungi indoors (all year)
Great Plains
Trees (February–April)—oak
Grass (April–September)
Weeds (July–October)—goosefoot, ragweed, and sage
Fungi (May–November)
Other—livestock dander, fertilizer dust, animal feed dust, grain, and storage dust
Western Mountain
Trees (January–March)—mountain cedar
Grass (May–August)
Weeds (July–October)—goosefoot, ragweed, and sage
Great Basin
Weeds (July–September)—goosefoot and sage
Southwestern Desert
Trees (January–April)—Arizona cypress, mountain cedar, and mulberry
Grass (March–October)
Weeds (April–September)—goosefoot and ragweed
Fungi (increased by use of evaporative cooling units in buildings)
California Lowland
Grass (March–October)
45
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Indoor Air Quality: The Latest Sampling and Analytical Methods
FIGURE 4.1
Differentiation between molds starts with the microscopic appearance of colonies and associated spores. This example demonstrates the spore-producing structures of two different genera of fungi that have similar size and shape spores. Both are around 2 to 3 microns in diameter
and are beadlike in shape.
The Cladosporium mold spores typically range between 4 and 20 microns in
length. Alternaria spores are around 30 microns in length (ranging from 8 to
500 microns), and Aspergillus/Penicillium spores are around 1 micron in diameter. It should be noted that some spore-producing bacteria are also on the
order of 1 micron in size and may appear microscopically to be mold spores
and cannot be differentiated without growing the spores in nutrient agar. See
Figure 4.1 for differentiation between two molds of similar spore production.
Pollen grains are typically denser and, on the average, larger in size than the
fungal spores. They range from 14 microns (for stinging nettle) to more than
100 microns in diameter. Tree and weed pollen are the more variable. Most, however, fall between 20 and 60 microns. Red cedar and Western ragweed pollen
are on the low end, around 20 to 30 microns. Scots pine and Carolina hemlock
are between 55 and 80 microns. Cedar pollen is around 30 microns in diameter.
Giant ragweed pollen grains are around 18 microns in diameter, and Noble Fir
pollen is around 140 microns. See Figure 4.2 for representative types.
Fungal spores are in the form of spheres, ovals, spirals, elongated stellates
(star-shaped), and clubs. They may be elongate, chained, or compact and,
generally, the surfaces are smooth. See Figure 4.3 for some shape differentiating features. They lack hairs, spicules (needles), and ridges, features common
to pollen grains, which are more complicated in design.
Pollen grains tend to be spherical or elliptical with surface structures and/
or pores, and the interior portions typically have a recognizable arrangement. They may be lobed with a smooth surface or spherical with spicules.
Their interiors may be thick walled, undifferentiated or thin walled, or
Pollen and Spore Allergens
47
FIGURE 4.2
Representation of allergenic plants and pollen categorized into trees [e.g., cedar (a)], grasses
(e.g., tall wheat (b)], and weeds [e.g., giant ragweed (c)]. The examples shown above are amongst
the more allergenic within their category. Photomicrograons courtesy of Sean D. Abbot, PhD,
Nature Link Mold Lab, Rerio, NV.
48
Indoor Air Quality: The Latest Sampling and Analytical Methods
(d)
(a)
(b)
(e)
(c)
(f)
FIGURE 4.3
Cladosporium (a), Alternaria (c), and Penicillium (e) are among the more commonly encountered
mold spores in the outdoor air environment. The sketches (b), (d), and (f) are relative size comparisons of the respective spore types. Photomicro graphs courtesy of Sean P. Abbott, PhD,
Natural Link Mold Lab, Reno, Nevada.
Pollen and Spore Allergens
49
multifaceted. Ragweed pollen is spherical with multiple spines, and pine
pollen grains are lobed with a smooth surface.
Plant pollen is generally more complicated in design than are the spores.
They tend to be spherical or elliptical with surface structures and/or pores,
and the interior portions typically have a recognizable arrangement. They
may be lobed with a smooth surface or spherical with spicules. Their interiors may be thick walled, undifferentiated or thin walled, multifaceted.
Ragweed pollen has a spherical morphology with multiple spines. The pine
pollen is lobed with a smooth surface.
Pollen densities range from 19 to 1003 grains per microgram. Hickory pollen is moderate in size, weighing in on the low end of the scale. Giant ragweed and nettle, even though small in size, are on the high end in density.
Spore-Producing Fungi and Bacteria
Both fungi and fungilike bacteria produce allergenic spores. Although the
most commonly encountered spores in indoor air quality are mold spores,
other fungal spores and bacterial spores can and frequently do contribute to
the total airborne spore count.
Fungi
Fungi, numbering more than 100,000 different species, are neither plant nor
animal. Lacking in chlorophyll (plantlike) and typically not motile (an animal characteristic), they belong to a kingdom of their own. The fungi kingdom consists of molds, yeasts, and mushrooms rusts, smuts, slime holds, and
yeasts. Where the yeasts are single-celled organisms, molds grow into long,
tangled strands of cells that multiply, forming visible colonies of varying
sizes, shape, texture, and diameter. Some fungi form complex fruiting bodies that are composed of tightly compacted masses of moldlike filaments and
are clearly visible to the naked eye. (e.g., mushrooms).
Molds
Mold spores are the most commonly referred to fungi. Their cell wall and protective spore surface is composed of polysaccharides (e.g., cellulose) and glucose
units containing amino acids (e.g., chitin). The cellulose component is plantlike,
and the chitin component is animal-like. It is the outer protective surface of the
mold, spores and growth structures that is thought to be that which elicits an
allergic reaction. For this reason spores are generally implicated in most allergy
conditions, sections of the growth structures can be allergenic as well.
Mold reproduction involves the release of thousands of allergenic spores,
each having the ability to reproduce long, threadlike hyphae that continue
to branch and form mycelia. The mycelium, in turn, attaches to a nutrient
substrate and grows. As long as the mycelium has nutrients and room to
50
Indoor Air Quality: The Latest Sampling and Analytical Methods
Aerial hyphae
Spores
Germination
Mycelium
Subsurface hyphae
Mycelium
FIGURE 4.4
Typical mold structures.
grow, a single mycelium may theoretically expand to a diameter of 50 feet.
See Figure 4.4 for diagram of mold structures.
Specific mold genera are reputed to provoke allergylike symptoms more
consistently than others. This may be due to the challenge by shear numbers
of a given species, or it may be due to one species being able to elicit a stronger reaction than another. See Table 4.3. It is not clear as to which is the case.
TABLE 4.3
Mold Spores (in Alphabetical Order)
Reported to Provoke Allergy Symptoms
Acremonium spp.2
Altemaria spp.2–5
Aspergillus spp.2–5
Aureobasidium pullulans2
Aureobasidium spp.4
Chaetomium spp.4
Cladosporium spp.4
Drechslera spp.2, 4
Epicoccum spp.4
Fusarium spp.4
Helminthosporium spp.5
Mucor spp.4
Nigrospora spp.4
Penicillium spp.2–5
Phoma spp.4
Rhizopus spp.4
Scopulariopsis4
rust molds and smuts5
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Pollen and Spore Allergens
TABLE 4.4
Most Common Airborne Allergenic Molds from 19 Random Surveys
Genera
Cladosporium
Prevalence (%)
Natural Habitats
29.2
Worldwide: soil, textiles, foodstuffs, and
stored crops
Region dependent: woody plants (e.g.,
straw) and paints
Worldwide: decaying plant matter,
foodstuffs, soil, and textiles
Region dependent: soil, decaying vegetation,
foods, cereals, textiles, and paints
Occasional occurrences: compost piles,
animal feces, paper/paper pulp, stored
temperature foods, cheeses, and rye bread
Region dependent: soil, stored cereal
products, soil, foodstuffs, dairy products,
textiles, compost, and house dust
Worldwide: soil and plants
Worldwide: soil, decaying pears and
oranges, paint, wood, and paper
Alternaria
14
Penicillium
8.8
Aspergillus
6.1
Fusarium
Aureobasidium
5.6
4.7
Source: From Al Doory, Y., and J.F. Domson. Mould Allergy. Lea & Febiger,
Philadelphia, Pennsylvania (1984). With permission.
Molds not commonly known to cause an allergic reaction may also contribute to the overall response of an individual’s immune system to those molds
that are reported to provoke allergy symptoms. Then, too, some authorities believe that individuals can develop an allergy to nonallergenic fungi
or become sensitized to a fungal spore that is not commonly a problem for
most people. Generally, however, allergenicity is genus or species specific.
An allergic reaction to one mold type does not necessarily follow that the
same will occur with another.
The most common airborne spore is Cladosporium. Beyond Cladosporium
there is some variation, based on geographic region and the time of the year.
The consensus appears to be for Alternaria as the second-largest contributor,
and many include Aspergillus and Penicillium. Ironically, most of these molds
are reputed causative allergenic agents for most mold-sensitive patients.
Table 4.4 provides percents of total airborne mold spores reported by one
source to represent the most common airborne allergenic molds. Most findings include many of the same genera with a slight variation on percent,
based on regional differences.
A single colony is capable of dispersing millions of spores in one day. See
Table 4.5. The spores are shot out of their capsule or dislodged from their
stalk and carried by the wind to be spread far and wide. Spores (and pollen)
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Indoor Air Quality: The Latest Sampling and Analytical Methods
TABLE 4.5
Number of Spore Discharges from One Source
Ganoderma applanatum
Daldinia concentrica
Penicillium spp.
30 billion/day
100 million/day
400 million/day
Source: From Smith, E.G. Sampling and Identifying Allergenic Pollens
and Molds: An Illustrated Identification Manual for Air Samplers.
Blewstone Press, San Antonio, Texas (1990). With permission.
travel, in extreme cases, as far as 1500 miles, and it is common to find them
100 miles from their point of origin. More simply stated, their source does
not necessarily have to be in the immediate vicinity.
Mushrooms
Mushrooms are filamentous fungi that typically form large structures,
called fruiting bodies. The fruiting bodies unite to form a large mass commonly referred to as the mushroom. A typical mushroom is comprised of a
fungal cap which produces millions of spores in the gills on the underside
of the mushroom; it may or may not have a stem. After a rain, mushrooms
pop up everywhere (e.g., fields, gardens, yards, etc.) and millions of spores
are discharged into the air. These myriad spores are visible as dark clouds of
dust billowing from the underside of the mushroom(s), and they contribute
to most of the outdoor airborne fungal spore population—particularly after
a rain shower. See Figure 4.5 for life cycle of mushrooms.
FIGURE 4.5
Life cycle of mushrooms.
53
Pollen and Spore Allergens
(a)
(b)
(c)
(d)
FIGURE 4.6
Source of indoor mushroom spores—dry rot (Serula lacrymans) fruiting body covered with millions of rust/red colored fungal spores (top left) and fungal-damaged lumber with cuboid-like
cracking of apparently dry wood (top right); white rot (Asterostroma spp.) growth on structural
wood supporting flat roof (bottom left); and white rot (Phellinus contiguous) growth on wet wood
around windows (bottom right). (Courtesy of Remedial Technical Services, United Kingdom)
Although it is unlikely that mushrooms will grow indoors without intent
(e.g., cultivation of edible mushrooms), mushroom-like fungi can and do
grow on wet structural lumber. Some grow away from a water source (e.g.,
saturated lumber in a crawl space), branch out, and grow into and damage
dry lumber. This fruiting body is referred to as “brown rot” (e.g., dry rot).
Other mushroom-like fungi (e.g., white rot) grow only at the water source
and only damage wet wood. See Figure 4.6.
Rusts and Smuts
Single-celled rust and smut proliferate to form thick-walled, binucleate
spores. With an excess of 20,000 species, “rust” fungi are so referenced due
54
Indoor Air Quality: The Latest Sampling and Analytical Methods
to an orange–red color imparted to diseased plants when the plants become
infected. Heavily infected plants look like they are covered with iron oxide
rust. Rusts do not grow indoors unless their host plants are present and
infected.
“Smut” fungi have more than 1000 species. The term smut is assigned
to this class of fungi because the thick-walled spores impart a black, sooty
appearance to plants. The levels of smut indoors are generally equal to or less
than that of the outdoor air, but if the smut and rust spore levels equal the
outdoor air, the fresh air is not adequately filtering the air.
Slime Molds
Slime molds are not true fungi but are related instead to the protists, and they
lack, for most of their lives, a cell wall. Laboratory reports refer to slime molds
by their taxonomic category—myxomycetes. The term slime mold refers to
the swarming bodies of amoeboid cells during part of their life cycle. In this
stage many of the slime molds display brilliant colors and appear mucoid on
a nutrient surface.
The slime molds have an interesting life cycle that includes a wet, amoeboidlike phase and a dry spore phase. See Figure 4.7. When conditions are
favorable, they live primarily on decaying plant matter (e.g., leaf litter and
logs) and bacteria-rich soils. Their food consists mainly of other microorganisms (e.g., bacteria and yeasts), and they ingest by phagocytosis. During the
wet phase they do not pose a problem.
During the dry phase, however, they form stalks that produce spores (or
multiple spore-containing sporangia) that are subsequently released into the
air. Slime mold spores can contribute to the total fungal spore count. It should
be noted, however, that their spores may easily be mistaken for smuts.
FIGURE 4.7
Life cycle of slime molds.
Pollen and Spore Allergens
55
Bacteria6
Bacteria are single-celled organisms usually less than 1 micron in diameter,
but they can be as large as 5 microns. The actinomycetes are filamentous
bacteria that can produce structures that have an appearance similar to small
mold spores and can contribute to the total allergenic spore count. Their
spores are also allergenic.
Actinomycetes are spherical or oval in shape and range in diameter from
0.8 to 3 microns, similar to that of Aspergillus/Penicillium. However, their
nutrient requirements are complex. They grow best in rich organic material
and tolerate extremes in temperature. Thus they do not grow in conditions
similar to those found in most office buildings, although extensive growth
of actinomycetes may be seen on building materials in damp crawlspaces.
Differentiating the mold and bacteria spores can be accomplished by microscopy or culturing viable spores.
Bacilli are rod-shaped, spore-forming bacteria. They are generally associated with food spoilage and are not likely to be airborne.
Indoor Source Information
Although indoor pollen grain exposures are generally less than outdoor
exposures, reduced pollen count indoors may still contribute to the total
allergen loading to which an individual is exposed. There are also exceptions to the rule in that indoor pollen counts, on rare occasion, may be greater
than outdoor counts. In the latter case, pollen may have entered a building
during the pollen season when the windows and doors were open and once
inside the building, the pollen enters into a recycling mode within a poorly
filtered air handling system. The investigator should not be blinded to all
possibilities.
Fungal spores also enter the indoor air from outside, and the total spore
count is generally less indoors than it is outside. With mold spores, the total
indoor mold spore count is typically 10 percent to 50 percent less than the
outside air. Yet unlike the pollen grains, molds and occasionally other fungi
can grow indoors. Not only does their growth contribute to the total count,
but some types of molds pose a greater health concern than others. For this
reason, an effort to identify fungal types is necessary to characterize their
impact.
Once again, there are exceptions to the rule in that indoor mold spores
may on occasion be greater indoors than outside. When this occurs at low
levels (e.g., less than 200 counts/m3 outside), it may be the result of outside
conditions that have minimized the outside mold spore count (e.g., immediately after a rain, which tends to settle particles and mold spores out of the
air), or it may be the result of normally low outside levels with amplification,
or growth, of molds indoors. Normal conditions will come with experience
in air sampling within a given region. For instance, outside airborne mold
56
Indoor Air Quality: The Latest Sampling and Analytical Methods
levels in St. Louis, Missouri, is typically in excess of 2000 counts/m3 (as high
as 62,000 counts/m3), whereas outside air in Las Vegas, Nevada, is normally
less than 100 counts/m3 (rarely higher than 2000 counts/m3). A clear case of
amplification indoors would be an outside level of 11,000 count/m3 and an
indoor exposure of 44,000 counts/m3.
Fungal species have different growth requirements, habitats frequented,
health effects, and levels of concern. Yet to capture and count all allergenic
fungal spores, the investigator must settle for a more generalized characterization of fungal spores and proceed to Chapter 5 for identification of genus
and, in some cases, species. See Table 4.4 for information regarding fungal
identification generally within the scope of the sampling methodology presented within this chapter.
Sampling Strategy
The investigator should determine the purpose for air sampling, and the purpose should assist the investigator to identify the area(s) to be sampled. They
may be based on identification of one, or a combination of the following: (1)
perceived worst case scenario(s); (2) representative of area(s) frequented; and
(3) areas of special concern (e.g., infant nursery). These sample areas should
be compared to at least one outside air sample and, if possible, one noncomplaint area such as may occur in an office building. Once the site or sites have
been selected, sample duration should be considered.
The occupants’ health and exposure duration are factors to consider when
deciding the type of air sampling to be performed. The exposure considerations for a healthy adult at work in an office building will be different from
that of an elderly patient confined to a hospital bed.
Activities should also be taken into consideration. Some activities may
impact the exposure levels more than others. For instance, maintenance
removing ceiling tiles in an office building may result in a twofold to
threefold increase in the spore counts. Custodial vacuuming and dusting
may result in increased counts. Aggressive agitation of bedding, textiles,
and clothing may result in increased counts. A humidifier may result in
decreased counts. Sometimes these peak exposure activities go unnoticed
without more extensive samples per site throughout the day or a time-discrete sampler.
Based on each scenario, the investigator must decide on the appropriate sampling method. These methods are typically short-term, snapshot
samples of several sites or short-term, time-discrete samples over a period
of time.
Pollen and Spore Allergens
57
Sampling and Analytical Methodologies
In indoor air quality sampling, the sampling methodologies of choice are
the slit-to-cover-slip sample cassettes (e.g., Allergenco-D, Air-O-Cell) and
slit-to-slide samplers (e.g., Allergenco™ Spore Trap, Burkard Spore Sampler).
They all perform on a similar principle but vary in up-front cost, ongoing
expenses, and ease of handling large sample numbers.
Try not to compare sample results taken by two different approaches.
Taking two samples using the same sampler at the same time and in the
same approximate location may result in differences because no two air samples are identical. Comparing samplers is a job for researchers. Choose one
sampler and stay with it.
Slit-to-Cover-Slip Sample Cassettes
The slit-to-cover-slip sampling methodology is often referred to as spore trap
cassette sampling. The cassette has a slit opening through which air passes
and particles adhere to the surface of a sticky substance (e.g., triacetin) on the
surface of a cover slip. The air is drawn through the cassette by means of an
air sampling pump. See Figure 4.8.
During sampling, the protective tape on either side of the cassette is
removed. The cassette is connected to a calibrated air sampling pump, air is
sampled for an abbreviated time period, and the cassette is resealed and sent
to a laboratory for analysis. A generalized summary of the method follows:
•
•
•
•
Equipment: air sampling pump and timer
Collection medium: spore trap cassette
Flow rate: 15 liters/minute
Recommended sample duration: 1 to 10 minutes, based on anticipated loading
Anticipated loading is based on conditions and activities. Where excessive
loading occurs on the slide, enumeration becomes difficult if not impossible.
In the latter case, samples may be significantly underestimated and difficult
to identify.
In clean office environments and outside where there is very little dust
anticipated, sampling should be performed for 10 minutes. In dusty areas
or areas where there is considerable renovation, a 1-minute sample should
be considered. Indoor air environments where there is moderate dust or
where considerable levels of mold spores (e.g., greater than 500 spores) are
anticipated, the sampling duration should be reduced accordingly (e.g., 5 to
8 minutes). Experience will be the investigator’s best guide.
58
Indoor Air Quality: The Latest Sampling and Analytical Methods
FIGURE 4.8
Spore Trap Sampler—Battery-operated Buck BioAir with Air-O-Cell cassette.
Slit-to-Slide Samplers
The slit-to-slide sampler operates by impacting particles onto a treated
microscope slide. An internal pump draws air through the slit at a flow
rate of 15 liters per minute. Sampling duration may be from 1 to 10 minutes, and the samplers can be programmed to collect a different sample at
designated sample intervals. For instance, the Allergenco™ Spore Trap can
be programmed to collect 24 discrete samples, once an hour for a total of 24
samples per slide.
With the ability to program the sampler, the investigator may find the slitto-slide sampler easier to manage than the cassettes. One location can be
assessed over an extended period and trends documented for time verses
concentration.
A generalized summary of the method follows:
• Equipment: Burkard™ 7-Hour Spore Trap or AllergencoTM Spore Trap
• Collection medium: treated microscope slide
Pollen and Spore Allergens
59
• Flow rate: 10 to 15 liters/minute
• Recommended sample duration: 5 to 10 minutes, based on anticipated loading
Analytical Methods
Samples are received, stained, covered (e.g., cover slip on the microscope
slide), and examined under an optical microscope. Counts are generally performed with a 40x objective, and identification may be performed using the
100x oil immersion.
The entire impacted surface area should be counted and results given in
terms of fungal spore characterization (e.g., myxomycetes) as well as spore
and pollen counts per cubic meter of air. Characterization identifies fungal
spores by categories (e.g., rusts) and mold spores by groups (e.g., Aspergillus/
Penicillium), and some of the more morphologically unique molds by genus
(e.g., Stachybotrys).
Commercial Laboratories
In recent years, commercial laboratories have been popping up like mushrooms after a heavy rain. They came, they saw, and they conquered. Although
there are attempts under way by universities (e.g., Harvard School of Public
Health) and nationally recognized organizations (e.g., American Industrial
Hygiene Association) to certify analysts and laboratories, many analysts are
inexperienced, and there is no quality control watchdog.
On the other hand, there are some very competent, experienced laboratories that charge a little extra, are not local, or have longer turnaround times.
The trade-off may be worth it. It can be disconcerting to compare two separate laboratory results of the same samples only to find one laboratory state
the counts are excessive while the other fails to detect any levels. If there is
a divergence from any of the basic laboratory approaches mentioned above
or the results appear inconsistent, seek a second opinion.
Helpful Hints
A dilemma that many investigators ponder is what equipment to purchase.
Should the investigator choose to perform time-discrete sampling, the
number of sample sites is limited by the number of impactors available.
Multiple sampling of several sites may be performed by any of the previously mentioned methods, and time-discrete sampling may be performed
by the environmental unit Burkard Spore Trap and the Allergenco™ Air
Sampler.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
The handling of the treated slides that are used in the impactor must be
done with caution. Once treated, the slides must be kept clean and should
not be touching other surfaces, including other microscope slides. The slide
may be maintained and transported in a box or plastic container specifically
made for this purpose.
This is generally not a problem with the single-use, disposable, spore trap
cassettes. The cassette air inlets are sealed prior to sampling and should
be resealed upon sample completion, but no manipulation of the adhesivecoated sample inside the cassette is required.
Although the initial cost of the air sampling pump for use with spore trap
cassettes is less than the slit-to-slide impactors, the cost of the cassettes can
quickly outweigh the initial cost of the impactors.
Due to its limitations, the Rotorod™ has not been discussed herein. Used
in the past for community allergy alert reporting (primarily pollen), the
Rotorod™ has a rotating rod with a built-in 24-hour interval timer. It is easy
to use, and the results are read in terms of counts/m3. Its limitation, however, is in the size of particles impacted onto the rod. There is a considerable
drop-off of smaller particles, particularly the spores that are most commonly
found to be problematic in indoor air quality (e.g., Aspergillus and Penicillium
molds).
When not able to program the sample time, use a good timer, preferably
one that counts down in seconds. Some timers count down in minutes, and it
is difficult to anticipate stop sampling time. The author prefers a timer with a
built-in turn off switch (e.g., darkroom clock). It is easy to become distracted
while waiting for the sample to be collected.
Keep notes of conditions at each sample location. These should include
exact location within the room, air movement (e.g., air supply not on while
sampling), distance from air supply vents, occupancy (e.g., nighttime no
occupancy), and activities (e.g., busy area). Many investigators also log temperature, relative humidity, and carbon dioxide levels.
Interpretation of Results
Although there are no indoor air quality standards for interpreting pollen
and mold spore counts, the National Allergy Bureau has set some guidelines based on ecological measurements for outdoor air. As health effects are
dependent on individual susceptibility, the relative exposure index is not
based on health effects. They are relative numbers and limits. Yet an investigator may excerpt in part or parcel usable information from these tables.
See Table 4.6.
61
Pollen and Spore Allergens
TABLE 4.6
National Allergy Bureau Guideline for Relative Exposures to Outdoor Air
Pollen and Spores (counts/m3)8
Allergen
Molds
Pollen
Very Low
Low
Medium
High
Very High
<500
1–50
500–1,000
50–100
1,000–5,000
100–500
5,000–10,000
500–1,000
>20,000
>1,000
The National Allergy Bureau is a section of the American Academy of
Allergy, Asthma and Immunology (AAAAI) Aeroallergen Network that is
responsible for reporting current pollen and mold spore levels to the media.
The network is a group of pollen and spore counting stations staffed by
AAAAI members who volunteer to donate their time and expertise in providing the most accurate and reliable pollen and mold counts from more
than 65 counting stations throughout the United States and Canada. They
use the seven-day long-term Burkard™ Spore Trap in the performance of
their sampling.
Beginning in 1992, the National Allergy Bureau compiled records reported
by each of the stations. These are broadcast to the media, and they are posted
on the Bureau’s Web site (http://www.aaaai.org/nab). These records and
additional allergy information can be accessed by the public.
As for assessing indoor air quality, sample results may require additional
considerations. The indoor counts should be compared to outdoor counts
and, if possible, to indoor noncomplaint areas, and the types of fungal spores
found indoors versus those found outdoors may be compared when assessing the potential source of mold spores as being indoors. Comparing low
levels of fungal spores, however, can be misleading.
According to former Harvard professor Harriet Burge11, the statistical
“probability of a calculated number representing the actual concentration
becomes significant at an actual count of about 10 spores.” For a 5-minute
sample at 15 liters per minute, the calculated concentration is 133 counts/m3.
She proceeds to point out that she considers concentrations less than 200
counts/m3 of little quantitative importance, regardless of taxon (i.e., mold
genus).
It is suggested that when making comparisons, do not place a whole
lot of credence on type and total concentrations of less than 200
counts/m 3.
Spore identification without observed growth patterns, but characterization and partial identification is useful in determining indoor amplification
of molds. See Tables 4.7 and 4.8 for generalized characterization of mold
types and for information regarding occurrence.
rotting food; very wet conditions
cellulose and leather; 84–88% relative moisture; some can
grow at freezing temperatures
rarely encountered indoors
cellulose; 65–98% relative moisture
widespread where moisture, especially in bathrooms and
kitchens, on shower curtains, tile grout, window sills,
textiles, liquid waste
rarely encountered indoors
grows on indoor plants; >93% relative moisture
Candida albicans is generally expelled by humans who
have been on long term antibiotics or steroids
“lumber mold”; associated with freshly cut lumber; indoor
exposures may not be associated with water damage;
>16% moisture content
rarely encountered indoors
cellulose
textiles, cellulose, moist window sills, wet duct insulation,
tile grout, places where relative humidity is greater than
50%; 82-88% relative moisture; some can grow in freezing
temperatures
soil, dead organic debris, hay, food stuffs
soil, dead organic debris, food stuffs, textiles (some plant
pathogens)
soil, decomposing plant material
soil, decaying plant debris, compost piles, stored grain
soil, forest soils, fresh water, aerial portion of plants, fruit
soil, plant debris, dung, insect parasites
soil, stored and transported fruit and vegetables, plant
pathogen, saprophyte on flowers, leaves, stems, and fruit,
leaf rot on grapes, strawberries, lettuce, cabbage, onions
endosymbionts
commercial lumber, tree, and plant pathogen
parasite of higher plants, causing leaf spot
soil, seeds, cellulose substrates, dung, woody and straw
materials
soil of many different types, plant litter, plant pathogen, leaf
surfaces, old or decayed plants
Arthrinium
Aspergillus
Aureobasidium
Beauveria
Botrytis
Candida (yeast)
Ceratocystis, Opiostoma
Cercospora
Chaetomium
Cladosporium
Substrates/Conditions for Growth Indoors
Alternaria
Where Found in Nature
Acremonium
Genus
Characteristics of Molds
TABLE 4.7
62
Indoor Air Quality: The Latest Sampling and Analytical Methods
variety of substrates
paper, textiles, and insects; >86% relative moisture
cellulose, cooling coils in air handlers, carpeting, textiles,
seeds and fruits; 86-91% relative moisture
variety of substrates, rotting food, soft fruits and fruit
juices; 90–94% relative moisture
rarely encountered indoors
rarely encountered indoors
jute fibers, paper, PVC, timber (oak wood), optical lenses,
leather, photographic paper, cigar tobacco, harvested
grapes, bottled fruit, and fruit juice undergoing
pasteurization; >80% relative moisture; some can grow at
temperatures as high as 122°F
cellulose, dried foods, cheeses, fruits, herbs, spices,
cereals, carpet, and glues; 80–90% relative moisture
rarely encountered indoors
cellulose, reverse side of linoleum (e.g., glue); cement,
paint, paper, wool, and rotting food (e.g., rice and butter);
spores not readily disseminated by air currents
cellulose
variety of substrates, found around wine cellars on
brickwork and adjacent timber
plant debris, soil, plant pathogens (particularly grasses)
plant debris, soil, secondary invader of damaged plants
soil, saprophytic or parasitic on plants, plant pathogens
organic matter, dung, soil
grasses, plants, and soil; decaying fruiting bodies of Russula
mushrooms
decaying plant material and soil
soil and decaying plant material, composting processes,
legumes, cottonseeds, some species parasitize insects
soil, decaying plant debris, compost piles, and rotten fruit
soil, blackened and dead herbaceous stems and leaf spots,
grasses, rushes, sedges
plant material, soil, fruit parasite
dead leaves, soil, grasses
soil, herbaceous substrates, and decaying wood
Drechslera, Bipolaris, and
Exserohilum
Epicoccum
Fusarium
Mucor
Myrothecium
Nigrospora
Paecilomyces
Penicillium
Periconia
Phoma
Pithomyces
Rhinocladiella
(continued)
plant debris, soil, facultative plant pathogens of tropical and variety of substrates
subtropical plants
Curvularia
Pollen and Spore Allergens
63
variety of substrates very wet conditions
cellulose, jute, wicker, straw baskets; 91–94% relative
moisture
rarely encountered indoors
cellulose
paper, tapestry, wood, rotting food
gypsum board, paper, paint, tapestries, jute, and other
straw materials; high water requirement, relatively dry
surfaces
wood/lumber in crawl spaces, textiles and mattresses
(e.g., likely to thrive on skin cells in dust); 65–87%
relative moisture
tree leaves, soil, rotting fruit, other plant materials,
associated with lesions caused by other plant parasites
soil, decaying plant substrates, decomposing cellulose (hay,
straw), leaf litter, and seeds
soil, wood, decaying vegetation, some species plant
pathogens
soil, dead herbaceous stems, wood, grasses, sugar beet root,
ground nuts, and oats surface of unglazed ceramics, and
cellulose
soil, decaying wood, grains, citrus fruit, tomatoes, sweet
potatoes, paper, textiles, damp wood
soil, dung, paint, grasses, fibers, wood, decaying plants,
paper, and textiles
soil, food stuffs, hay, textiles, salted fish
Sporobolomyces (yeast)
Stachybotrys
Stemphylium
Torula
Trichoderma
Ulocladium
Wallemia
Excerpted from “Characteristics of Some Commonly Encountered Fungal Genera.”10
Supplimented from “Ecometrex Fact Sheet-Moisture Requirements for Mold Growth.” www.ecometrex.com/moisture.htm;
“Candida (genus).” www.en.wikipedia.org/wiki/Candida_(genus); and “Pasteur Laboratory-Some Common Fungi and Their Health Effects.” www.
pasteurlaboratory.com/common1.htm
cellulose—drywall paper, cellulose ceiling tiles (not fiberglass), jute (e.g., natural capet backing), and untreated lumber
variety of substrates, food; 90-93% relative moisture
Substrates/Conditions for Growth Indoors
forest and cultivated soils, decaying fruits and vegetables,
animal dung, and compost; a parasitic plant pathogen on
cotton potatoes, and various fruits
Where Found in Nature
Rhizopus
Genus
Characteristics of Molds
TABLE 4.7 (CONTINUED)
64
Indoor Air Quality: The Latest Sampling and Analytical Methods
decaying logs, stumps and dead leaves,
particularly in forested regions
grasses, flowers, ferns, and trees
cereal crops (e.g., corn and wheat),
grasses, weeds, and flowering plants
saprophytic or parasitic on higher plants
and other fungi
grows on lichens and vertebrates
rarely found growing indoors (e.g., indoor plants)
rarely found growing indoors (e.g., indoor plants)
“dry rot”—fungus originates in wet lumber (e.g., wet soil
in crawl spaces, leaking roofs and windows), migrates
to/through and damages dry lumber (dry, cracked wood)
“white rot”—wet lumber, does not migrate beyond
moisture source
surfaces in high humidity areas (e.g., tiles in bathrooms
and sheet vinyl in around dishwashers); spores not
readily disseminated, more likely encountered on surface
samples
rarely found growing indoors (e.g., wet decaying wood)
saprophytes and plant pathogens
gardens, forests, woodlands
Substrates/Conditions for Indoor Fungal Growth
damp soil (e.g., indoor plants)
very wet organic material (e.g., wood and natural fiber
carpeting)
Where Found in Nature
saprophytes and plant pathogens
a
Categories of fungal spores are spores that cannot be differentiated by spore trap analysis only. The term “category” is a laboratory designation, not a
means of classification.
NOTE: As the indoor fungal levels typically lag that of outdoors, amplification is indicated only in extreme cases such as where indoor levels exceed
outdoor levels ten fold. Less than a two fold elevation indoors over that of outdoors may reflect what the outdoor levels were two days prior and
have yet be flushed from the air handling system.
Rusts
Smuts
Myxomycetes: slime molds
Ascospores: large fruiting bodies whose
spores are produced inside a sack (e.g.,
morels, truffles, cup fungi, ergot, and many
micro-fungi)
Basidiospores: large fruiting bodies whose
spores are produced externally (e.g.,
mushrooms, puffballs, shelf fungi, bracket
fungi, earth stars, stinkhorns, jelly fungi,
and other complex fungi)
Coelomycetes: assexual filamentous fungi
that form conidia in a cavity or mat-like
cushion of hyphae
Categories of Sporesa
Broad Categories of Fungal Spores Identified by Spore Trap10
TABLE 4.8
Pollen and Spore Allergens
65
66
Indoor Air Quality: The Latest Sampling and Analytical Methods
Summary
There are no standards for interpreting pollen/spore counts and their effect
on human health. The investigator can assess total relative pollen and spore
counts and, to a limited extent, compare types to determine amplification
indoors. For a more thorough identification and comparison of types in determining indoor amplification of molds, the investigators should also perform
viable mold air sampling in tandem with the viable/nonviable methods in
this chapter. See Chapter 5.
References
1. Aeroallergen Network of the American Academy of Allergy, Asthma and
Immunology (AAAAI). U.S. Pollen Calender. AAAAI, Milwaukee, Wisconsin
(July 1993).
2. Smith, E.G. Sampling and Identifying Allergenic Pollens and Molds: An Illustrated
Identification Manual for Air Samplers. Blewstone Press, San Antonio,
Texas (1990), p. 43.
3. ACGIH. Bioaerosols: Airborne Viable Microorganisms in Office Environments
Sampling Protocol and Analytical Procedures. Applied Industrial Hygiene (April
1986), p. R 22.
4. Cole, G.T., and H.C. Hock. The Fungal Spore and Disease Initiation in Plants and
Animals. Plenum Press, New York, New York (1991), p. 383.
5. Al Doory, Y., and J.F. Domson. Mould Allergy. Lea & Febiger, Philadelphia,
Pennsylvania (1984), pp. 36–7.
6. Smith, E.G. Sampling and Identifying Allergenic Pollens and Molds: An Illustrated
Identification Manual for Air Samplers. Blewstone Press, San Antonio, Texas (1990),
p. 16.
7. Ibid. p. 42.
8. Pinnas, J.L. Parameters for Pollen/Spore Charts (Letter). National Allergy Bureau,
Tucson, Arizona (November 28, 1994).
9. Bleimehl, L. Issues Concerning the National Allergy Bureau (Oral communication).
AAAAI, Milwaukee, Wisconsin (January 1996).
10. Abbott, Sean (discussion) Natural Sink Mold Lab October 20, 2010. Categories of
spores and where/when they are found window.
11. Burge, H. What Is the Proper Way to Interpret Mold Reports? Indoor Environ­
mental Connections (newspaper), 11:3 (January 2010), p. 15.
5
Viable Microbial Allergens
Microbial allergens are microscopic organisms that may cause allergy symptoms. Mold spores are the most commonly recognized microbial allergens,
reported to affect more than 20 percent of the adult population. Other less
commonly recognized microbial allergens are spore‑forming bacteria.
Microbial organisms may be culturable (i.e., grown under laboratory conditions), nonculturable, or dead, and they may elicit the same effect, irrespective of viability. On the other hand, not all microbes are allergens. Some are
human pathogens (e.g., tuberculosis). Many affect our lifestyles (e.g., mold in
the home) and crops (e.g., crop pathogens). Others have no apparent, direct
impact on our lives. Yet they may all be airborne.
Airborne microbial allergens are indoors and outdoors. Generally, the outdoor levels are greater than the indoor levels. Even when the outdoor levels
exceed the indoor levels, identification of the indoor and outdoor microbial
allergens by genus and species is a means for determining amplification
indoors. This is done by culturing viable microbes. A viable organism is one
that is capable of growing and completing a life cycle. Thus microbes can
only be reliably differentiated when their viability is retained. If they are
dead, cannot grow on culture media, or cannot form spores when grown on
culture media, microbial allergens cannot be identified.
Although the health effects of viable allergens and nonviable allergens are
the same, sample collection and interpretation methods are distinctly different. Airborne viable microbial air sampling is more involved than nonviable
sampling. Viable air sampling is the only way to definitively identify mold
spores by genus and species, but other fungal spores (e.g., smuts and rust) are
rarely cultured. In the latter, the most efficient way to sample is for viable/
nonviable spores.
The information obtained through viable sampling contributes significantly toward the overall picture and interpretation of exposures to mold
spores. Mold spores are a major contributor to indoor air quality allergens.
Occurrence of Allergenic Microbes
Viable allergens are herein discussed to lend an understanding to the reader
as to the potential sources and growth requirements needed for enhancement and amplification of allergenic microbes. The principal allergen in
67
68
Indoor Air Quality: The Latest Sampling and Analytical Methods
each case is thought to be airborne spores with minimal concern for the
associated growth structures. The two major categories are fungi and thermophilic actinomycetes.
Those microbes which have been excluded from this allergenic microbes
list are either pathogenic or have not been reported as probable allergens.
The pathogenic microbes are discussed separately in Chapter 6.
Fungi
Molds and other fungal allergens were discussed in the preceding chapter
under the section “Spore‑Producing Fungi and Bacteria.” Yet the intent was
to discuss basic characteristics, not differences between the specific fungi.
As they can be more readily identified, we discuss herein details regarding
specific fungi, their habitats, and unique characteristics.
Molds
Contrasted with the hardiest of microbes, molds not only can stay alive
indefinitely on inanimate objects, or fomites, but they can grow into and
destroy wood, cloth, fabrics, leather, twine, electrical insulation, and many
other commercial products. They destroy lenses of microscopes, binoculars,
and cameras. In localities where humidity is high, fungi do great harm to
wood structures, telephone poles, railroad ties, and fence posts. Most of
these problems are reduced by means of artificial preservatives. Sometimes
the trouble starts in forests where fungi invade the heartwood and cause
wood rot before the timber has had a chance to be cut down. The humid
Amazon rain forest is one such example.
Thousands of products are treated to prevent decay, yet there are some
types of fungi that thrive on preservative‑treated wood. One such example is creosote‑treated railroad ties! Other fungi‑specific nutrients are vinyl
wall covering adhesives, gypsum board, cellulose‑based ceiling tiles, dirt
retained within carpeting, and surface paints. Some feed on plywood. Others
consume the glue used to laminate wood that is used in airplanes, furniture, and cars and will cause the layers to separate. Books and leather shoes
are readily consumed by the microbes that are visible as mildew. Aircraft
electrical systems, operating in tropical climates, require protection against
insulation‑consuming molds. Immune‑suppressed individuals (e.g., AIDS
patients) can also be host to normally nonpathogenic molds.
Exterior molds grow on decayed organic material, corn, wheat, barley, soybeans, cottonseed, flax, and sun‑dried fruits. They consume other plants,
vegetable matter, and decayed organic material (e.g., dead animals).
Pathogenic molds parasitize and obtain nutrients from a host. The host may
be plant or animal, and these molds vary slightly from the nonpathogenic
molds both in environmental and sampling requirements. Thus they are discussed in greater detail in Chapter 6.
69
Viable Microbial Allergens
TABLE 5.1
Moisture Requirements of Common Microorganisms
Water Activity
(% Relative Moisture)
Microorganism
Aspergillus halophilicus and Aspergillus restictus
Aspergillus glaucus and Wallemia sebi
Aspergillus chevalieri, Aspergillus candidus,
Aspergillus ochraceus, Aspergillus versicolor,
and Aspergillus nidulans
Aspergillus flavus, Aspergillus versicolor,
Penicillium citreoviride, and Penicillium citrinum
Aspergillus oryzae, Aspergillus fumigatus,
Aspergillus niger, Penicillium notatum,
Penicillium islandicum, and Penicillium urticae
Yeasts, bacteria, and many molds
0.65–0.70
0.70–0.75
0.75–0.80
0.80–0.85
0.85–0.90
0.95–1.00
Source: ICMSF. Microbiological Ecology of Foods. Academic Press, New York (1980).
With permission.
Most molds require high moisture in order to grow. Most require moisture content in excess of 80 percent, some do quite well at levels as low as
60 percent. The latter are referred to as xerophylic (dry‑loving) fungi. Whereas
Stachybotrys requires considerable moisture (91–94% relative moisture at a
lower level (80–85% relative moisture). Mold that requires low moisture levels is inhibited by high moisture content. Aspergillus versicolor does well. See
Table 5.1 for water requirements of some of the more common microorganisms, and see Table 5.2 for moisture requirements of the more common fungi,
identified by moisture preferences.
Temperature preferences are variable as well. Although most molds
do well at room temperature, some flourish at near-freezing temperature
TABLE 5.2
Moisture Requirements of Common Fungi
Water Requirement
Common Indoor Fungi
Hydrophilic fungi
(>90% minimum)
Fusarium, Rhizopus, and
Stachybotrys
Mesophilic fungi
(80% to 90% minimum)
Altemaria, Epicoccum,
Ulocladium, Cladosporium,
Aspergillus versicolor
Eurotium (Aspergillus
glaucus group), and some
Peni­cillium species
Aspergillus restrictus
Xerotolerant
(<80% minimum)
Xerophilic fungi
(<80% preferred)
Typical Sites
Wet wallboard, water
reservoirs for humidifiers,
and drip pans
Damp wallboard and fabrics
Relatively dry materials
(e.g., house dust where high
relative humidity)
Very dry and high sugar
foods and building materials
Source: ACGIH. Bioaerosols. ACGIH, Cincinnati, Ohio (1999). With permission.
70
Indoor Air Quality: The Latest Sampling and Analytical Methods
TABLE 5.3
Temperature Relations of Common Mold Species
Temperature to Kill Most “Mold Spores” (within 30 Minutes)
Maximum growth temperatures
Optimum growth temperature
Minimum growth temperature
86–104°F
72–90°F
41–50°F
Source: Crissey, J.T., H. Lang, and L. Parish. Manual of Medical
Mycology. Blackwell Science (1995). With permission.
(e.g., refrigeration), and some thrive at temperatures in excess of 100°F (e.g.,
hot tubs). Although most spores favor moderate temperatures, the investigator should be aware of the potential for growth and amplification of
molds in just about any temperature setting. The ranges are presented in
Table 5.3.
Fungi tend to grow more during months when the humidity and temperature are elevated. In some regions, the peak mold spore season is in the spring,
followed by the summer months. Other areas of the country experience peak
periods in the fall. The winter months typically provide the least accommodating conditions for fungal growth. Although the daily and monthly variability is
based entirely on humidity and temperature, growth will increase or decrease
at certain hours of the day or night regardless of the outdoor climate.
Many, not all, fungi have peak growth times that are genus, sometimes
species, dependent. Some peak in the late of night (e.g., Cladosporium and
Epicoccum). Others peak in the early morning. Some peak in the late afternoon (e.g., Alternaria and Penicillium). A few peak, irrespective of time frame,
immediately after a heavy rainfall.3 Studies vary on their opinion as to these
times, yet they all agree that peak periods do exist.
Indoor air environments may vary in humidity content of the air along
with the outdoor air environment, and peak mold seasons may correlate to
the indoor environment, particularly where humidity controls are not maintained. High humidity (greater than 60 percent relative humidity) is thought
to be the leading cause of fungal amplification within buildings.
Other means of mold spore amplification include, but are not limited to: (1)
settled water sources (e.g., air handling system drip pans); (2) damp building
materials (e.g., wet ceiling tiles); (3) air movement from a hot, humid crawl
space into an occupied office area; (4) disturbances of settled dust (e.g., dry
dusting); and (5) poor vacuum cleaner filtration. It should also be noted that
mushrooms have been identified in buildings where water‑damaged carpeting has been left uncorrected and other areas where there is an accumulation
of water (e.g., behind leaking washing machines).
Molds grow in wide ranges of pH. Although a pH of 5 to 6 is favored by
most, some molds proliferate between pH 2.2 and 9.6. Rare forms have been
found consuming nutrient impurities found in bottles of sulfuric acid.
Viable Microbial Allergens
71
FIGURE 5.1
Photomicrographs of allergenic molds with their growth structures. They are: Penicillium spp.
(top left), Scopulariopsis spp. (top right), Verticillium (middle left), Alternaria (middle right), and
Aspergillus niger (bottom left). Mold structures and spores stained, photos taken under 1000X
oil immersion. Photomicro graphs courtesy of Sean P. Abbott, PhD, Natural Sink Mold Lab.
As fungi typically require oxygen, they tend to grow in oxygen rich environments (e.g., air handling systems). Some, however, grow quite well in
enclosed areas where the oxygen may be minimal (e.g., between vinyl wall
coverings and the wall). Yet they all do require some oxygen. There are no
anaerobic fungi.
72
Indoor Air Quality: The Latest Sampling and Analytical Methods
Budding Cells
(a)
(b)
(c)
FIGURE 5.2
Yeasts RhoIdotorula (a), SporoboIlomyces (b), and capsulated Cryptococcus neoformans (c).
Yeasts
Yeasts, one‑celled fungi, are usually spherical, oval, tube‑shaped, or cylindrical in shape. They usually do not form filamentous hyphae or mycelium.
A population of yeast cells remains a collection of single cells or budding
structures. See Figure 5.2. They can be differentiated from bacteria only in
their size and internal morphology (with an obvious presence of internal cell
structures). Some of the yeasts reproduce sexually. The sexual reproductive
process forms an ascospore that is resistant to many environmental conditions. They tend to grow on nutrient agar intended for molds, and they are
generally reported along with the molds on a cultured sample.
Yeasts usually flourish in habitats where sugars are present (e.g., fruits, flowers, and the bark of trees). The most important ones are the baker’s and beer
brewer’s yeasts. These have been selected and manipulated by man. They do
not serve as good representatives of the classification. They are atypical.
Although not common, yeasts have been reported growing indoors on
wet, rotting wood and other high moisture content surfaces. When this
occurs, the indoor yeast levels may exceed the outdoor levels. This is, however, rare. Those that are routinely found in indoor air quality investigations
are Rhodotorula (shiny pink colonies on malt extract agar) and Sporobolomyces
(salmon‑pink or red colonies on malt extract agar). Cryptococcus neoformans is
a pathogenic yeast that produces a thick protective capsule.5
Bacteria 5
Bacteria are single‑celled organisms ranging in size from 0.8 to 5 microns in
diameter. Their surface structure is complex, and they are limited in form.
They may appear as spheres (e.g., cocci), straight rods (e.g., bacilli), or spiral
rods (e.g., spirochetes), or branched filaments (referred to as actinomycetes).
Some bacteria produce endospores, or internal spores, which are resistant
to environmental stresses. Endospores may be allergenic, and they may survive harsh conditions for extended periods. During this dormant period,
73
Viable Microbial Allergens
endospores remain viable and allergenic. They can remain dormant for years.
The most commonly known endospore‑producing bacterium is the genus
Bacillus, some species of which are also pathogenic. Actinomycetes normally
produce spores that are readily released into the environment without the
need for environmental stressors.
Both Bacillus and actinomycete bacteria can be allergenic, and they require
different nutrient agar than that required by molds. They require special
media and some actinomycetes require elevated incubation temperatures.
They are not likely to show up on mold culture plates.
Bacillus
The genus Bacillus is a gram‑positive, rod‑shaped bacterium that is known to
form endospores under stress conditions See Figure 5.3. Bacillus endospores
have been implicated as a cause of hypersensitivity pneumonitis, and the
endospores have been found indoors as well as outdoors.
Bacillus bacteria thrive on dead or decaying organic material. The spores
are normally found in soil, dust, and water. They can also be found in dry
desert sands, hot springs, arctic soils and water, pasteurized milk, stored
vegetables, various foodstuffs, and feces.
As the most common concern is typically molds, bacterial endospores are
often overlooked during indoor air investigations. For this reason, there has
been minimum research and publications regarding this topic. Some have
speculated that high levels of Bacillus in indoor air is a barometer of past
conditions. Either the HVAC system or the building was subject to extreme
water damage, saturation, or lack of maintenance.
Although some species of Bacillus are lethal (e.g., Bacillus anthracis), most
Bacillus bacteria are not pathogenic and are rarely associated with disease.
The greatest concern herein is allergenicity.
Bacteria
FIGURE 5.3
Bacillus rod‑shaped bacteria and oval endospores.
Endospores
74
Indoor Air Quality: The Latest Sampling and Analytical Methods
Spores
Mycelia
FIGURE 5.4
Thermophilic actinomycetes are fungus-like bacteria.
Thermophilic Actinomycetes
Actinomycetes are filamentous bacteria that resemble fungi in their colonial
morphology and production of allergenic spores. See Figure 5.4. Under the
microscope, colonial masses appear as thin hyphae (generally much thinner
than those found in fungi) with associated spores that are at the low size range
for fungal spores.
Ideal temperature preferences range from 25°C to 60°C. Yet these ranges
may at times be narrow and highly selective. Thermoactinomyces candidus
grows rapidly between 55°C and 60°C but will not grow at 37°C or less.
Although most thermophilic actinomycetes will grow at 37°C, many prefer
45°C to 55°C.
Their nutritional requirements are more complex than that of molds, and
their spores are more temperature resistant. Thermophilic actinomycetes
form allergenic spores and can be differentiated from the molds by selective
culture media and observation of growth patterns.
The most commonly encountered genera are Micropolyspora, Thermo­actin­
omyces, and Saccharomonospora. Some species of Streptomyces have been implicated as allergens as well. In nature, these organisms generally require a
nutritionally rich substrate and elevated temperatures. Ideal habitats include
moldy hay, compost, manure, and other vegetable matter. Indoor amplification may occur in the heating and humidifying systems where there is also
a source of nutrients (e.g., vegetable matter buildup in an air handler with
elevated temperatures).
Air Sampling Methodologies 6
There are no federal government requirements for monitoring nor are there
clearly defined methodologies. Although there have been a few attempts
by professional organizations, universities, and private firms to provide
Viable Microbial Allergens
75
guidelines, the most readily accepted guidelines have been set forth by the
American Conference of Governmental Industrial Hygienists (ACGIH). Its
latest publication, Bioaerosols: Assessment and Controls, is frequently referenced
herein.
Sampling Strategy
The sampling strategy is subject to the investigator’s evaluation of each specific situation. There are a few basic guides to aid the investigator, but they
are not hard and fast rules. Careful thought and planning are paramount.
When and Where to Sample
According to the ACGIH, to anticipate high and low exposures, minimum
sampling efforts should include a least one, preferably three, sample areas in
each of the following areas:
• An anticipated high exposure area (e.g., an area identified as central
to health complaints)
• An anticipated low exposure area (e.g., an area identified and confirmed to have minimum health complaints)
• Outdoors near air intakes for the building (e.g., on the roof or along
the side of the building where fresh air is taken to supply the indoor
area(s) to be sampled)
Other sample sites that should be included are:
• Outdoors near potential sources of bioaerosols that may enter a
building (e.g., fresh air entry from open or frequently used doors
and windows downwind from a creek bed or waste container)
• Outdoors high above grade and away from potential bioaerosol
sources (e.g., background levels not affected by the immediate building environment)
When assessing fungal growth contributions from a ventilation system,
locate a site near one of the air diffusers associated with the air handling
unit in question. Then take samples at different times during the unit’s cycle.
Consider the following:
• After the air handling unit has been turned off (generally occurring over a weekend), preferably prior to restart after a weekend of
down time
• After the air handling unit has been turned on, restarted after a
weekend
76
Indoor Air Quality: The Latest Sampling and Analytical Methods
• After the air handling unit has been operating for 30 minutes
• During mechanical agitation of the ductwork, preferably when a
space is unoccupied and in a fashion to simulate normal maintenance activities or other normal disturbances that might occur to the
duct work
Equipment
Although there are several possible choices for sampling equipment, selection is situation dependent. No single sampler can meet all needs. The choice
may be a combination of accessibility, reliability, and functionality, or it may
be familiarity.
Slit‑to‑Agar Impactor
The slit impaction sampler operates by rotating a culture plate below a long,
narrow slit, or inlet. The collection substrate may remain stationary, move
continuously, or move in increments beneath the slit.
An internal pump draws air through the slit at a flow rate of 50 liters per
minute, and the air is impacted onto 10‑ or 15‑centimeter diameter plates
with nutrient agar. Sampling duration may be from 1 to 60 minutes.
An advantage to this technique is that slit‑to‑agar impactors have a wide
range of detection and provide limited time‑differential information. A disadvantage is that is they are not as readily recognized as other samplers and
have not been time tested.
Multiple Hole Impactor
The sieve impactor operates by the passage of an air stream through evenly
spaced, machine sized holes. The single‑stage Andersen impactor has been
time tested and is the most frequently chosen equipment for viable microbe
sampling.
A high‑volume pump draws air through the impactor at a flow rate of
28.3 liters per minute, or 1 cubic foot per minute. At this preset flow rate,
particles of a given size (e.g., greater than 0.65 micron in size) are deposited
onto the surface of a collection medium (e.g., petri dish). Faster flow rates
will result in the deposition of smaller particles and potentially in loss of
viability. Slower flow rates will only deposit larger particles. For this reason, it is important that the flow rate be as designed for the most effective
collection.
A disadvantage is that the samples are limited in duration. A typical
sampling period is from 1 to 5 minutes. Either multiple samples must be
taken and averaged over an extended time period (e.g., 8 hours) or random
sampling must be accepted as representative of exposures throughout an
Viable Microbial Allergens
77
exposure period. Some professionals have monitored for up to 30 minutes.
However, there is a risk of oversampling and loss of viability.
Liquid Impingers
Familiarity and simplicity are the principal advantages to the liquid impin­
gers. They operate by the passage of an air stream through and inertial
impaction on a liquid. The liquid may be a sterile solution of water (or surfactant), mineral oil, or glycerol. The latter two retain the viability of the sample
more effectively than water. All three liquids minimize dehydration.
Do not be confused into thinking a typical industrial hygiene impinger
will work. A high‑volume pump draws air through a special all‑glass impinger
(AGI) at a flow rate of 12.5 liters per minute. The AGI has a pre‑established
distance between the tip of the inlet jet to the base of the impinger.
The AGI‑4 distance to the base is 4 millimeters, and the AGI‑30 distance
is 30 millimeters. Although a more efficient “particle” collector, the AGI‑4
results in greater physical stress because of its shorter distance to the bottom of the impinger. Recovery of viable microbes is more likely with the
AGI‑30.
Although efficient for collecting a diverse range in particle sizes, this
method does not have a high recovery efficiency for hydrophobic bacteria
(e.g., Bacillus) and some mold spores in water. Recent research, however,
indicates effective recoveries in mineral oil and glycerol. Both require considerable static pressure to overcome resistance to air movement through
the fluids and filtration necessary upon receipt by a laboratory. The latter
is meeting with considerable resistance due to the difficulty of separating
spores down to 1 micron in size from the viscous liquids.
Upon separation, samples can be diluted and plated onto several different
nutrient agar. This process allows for different media to be inoculated from
the same sample and may permit greater sampling times than the recommended 30 minutes. Yet more experience is needed with the AGI to reach a
level of competency attained by some of the others.
Filtration
Familiarity, simplicity, and long-term sampling are the principal advantages
to the filtration. Although efficient for collecting a diverse range in spore
sizes, sample collection and filter clearance have a severe drying effect on the
collected allergens, and analysis results in underestimated spore counts.
Smooth‑surfaced filters (e.g., polycarbonate) are less damaging than the
coarser filters, and some of the larger industrial hygiene supply companies
are developing hydrated filters to overcome the drying effect of long-term
sampling. The sample airflow rate is 1 to 5 liters per minute.
Sampling duration is variable, up to 24 hours, and air volume may be up
to 1000 liters. The higher flow rates and the longer sampling times will result
78
Indoor Air Quality: The Latest Sampling and Analytical Methods
in even a more extensive loss of spore viability. Filtration is discouraged for
the more fragile bacteria.
Centrifugal Agar Samplers
Longer sampling duration and ease of use are the principal advantages to
the centrifugal agar sampler. It operates by a rotating drum that draws air
at a flow rate of 50 liters per minute with impaction of particles onto the surface of manufacture supplied agar strips. The sampling duration is up to 20
minutes. Although not all laboratories are familiar and capable of analyzing
agar strips, this approach is becoming more widespread.
Sample Duration
Equipment, airflow rates, and culture plate limitations are the limiting factors
in sample duration. The most commonly used sampling equipment requires
a sample duration of 1 to 60 minutes, a small snapshot in the overall exposure time. Airflow rates are preset, not subject to change, and culture plates
can become overloaded if too much air volume is sampled. The sample duration is the only variable that can be adjusted—knowing the limitations.
Ideally, the investigator wants to collect a minimum number of colony
forming units (CFU) with a maximum number of microbial growths per
plate. Overloading can render the sample unreadable. Note that some labs
will attempt to read overloaded plates and report a greater than number.
The ACGIH recommends an optimal collection of 10 to 60 CFU/plate. Yet
in order to stay within this range, the investigator must anticipate the
exposures.
For example, with a single‑stage Andersen impactor, the lower detection
limit would be 35 CFU/m3 for a 10‑minute collection time, and the upper
detection limit would be 5570 CFU/m3 for a 30‑second collection time. Once
again, the sample duration is based on anticipated exposures. Professional
judgment comes into play!
Sample Numbers
With limited sample durations of less than 10 minutes in most cases and
60 minutes in others, monitoring the entire exposure time would require
multiple samples—an unfeasible proposition. Thus a logical, well-thoughtout selection of sampling time(s) is necessary to obtaining results that can be
readily interpreted with minimal speculation.
Either the investigator may choose to sample during an anticipated worst
case scenario (e.g., respondents on questionnaires state that their symptoms
are worse on Monday mornings or after custodial activities), or the investigator may choose to take two to three samples at each site throughout the day.
Some investigators may choose to sample every other hour throughout the
exposure period. Larger sample numbers result in greater data reliability.
Viable Microbial Allergens
79
Yet on the practical side, larger sample numbers result in greater expense.
The decision on the number of samples to be taken becomes a difficult decision of weighing all factors. See Figure 5.1.
Culture Media
There is considerable controversy as to the appropriate medium to use. Not
all molds will grow and create recognizable spore‑forming structures on a
single nutrient agar. This is one of the single most important and controversial issues in sampling for molds.
General Information
The choice of culture medium is dependent upon the organism(s) the investi­
gator seeks to identify and on the laboratory’s choice. Keep in mind that
there is no single medium upon which all fungi or bacteria will grow. Not all
can be cultured, and not all molds will form identifying spores. The failure
to form identifying spores is generally reported as nonsporulating colonies
or mycelia sterilia.
The best, most commonly used culture medium for airborne fungi is malt
extract agar (MEA). This medium supports the growth of most viable fungal
spores, and MEA is an excellent medium for identifying species. Species identification is sometimes important, not only for allergen amplification determination, but for identifying species that may have other effects. For example,
Aspergillus flavus can be deadly for immune‑suppressed individuals.
Some media inhibit the growth of undesirable competitors. Rose Bengal
agar (RBA) is used for fungi while bacterial growth is kept to a minimum. In
some environments where high bacterial levels are anticipated (e.g., agricultural environments), RBA would be the medium of choice.
Stachybotrys molds grow on cellulose agar. Although some laboratories
claim this medium is best suited for Stachbotrys, some laboratories have demonstrated that Rose Bengal agar works equally well. The trend, however, is
toward cellulose agar when Stachybotrys mold is the focus.
Bacillus as well as environmental and human commensal bacteria grow
well on R2Ac agar with cycloheximide, a fungal suppressant. Bacillus and
thermophilic actinomycetes will grow on tryptic soy agar (TSA). Bacillus and
pathogenic bacteria will grow well on blood agar (BA). As different species
grow in variable temperature ranges, the choice of medium for Bacillus may
also be dependent upon the anticipated temperature tolerance for the bacteria under investigation. In an indoor air quality investigation, the most likely
Bacillus to grow will be that which grows at room temperature. In this case,
the R2Ac would be the medium of choice.
The preferred medium for thermophilic actinomycetes is tryptic soy agar.
The thermophiles grow best at elevated temperatures as do the pathogenic
bacteria. Elevated temperatures tend to kill or suppress growth of other
organisms.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
The thermophilic actinomycetes are incubated at 56°C, and the commensal bacteria are grown at 35°C. All others are grown at room temperature
(i.e., 23 ± 3°C).
Special Comments
Plated culture medium can be purchased from a laboratory supply retailer
(e.g., Remel or Difco), and some microbial laboratories supply media to their
clients. The latter is preferred.
For use in impaction samplers, the plated medium should be evenly distributed in the petri dish. If it has melted during transportation and is not
level upon receipt, do not use the plate. Impaction is based on distance from
the air holes to the surface of the agar. If the agar is not flat, the impaction
will result in poor sample collection and inconsistent counts.
Culture media dries out after four to six weeks. So don’t overstock.
Understocking may pose a problem as well. Order for anticipated needs with
a minimum 10 percent excess. Keep in mind, the plastic dishes may crack in
transit, or the investigator may inadvertently contaminate a plate (e.g., sticking a finger into the agar) and require replacement. The perfect world does
not exist outside the laboratory.
Equipment must be calibrated to assure adequate flow. This may be up to
the discretion of the investigator. Most investigators do not have adequate
equipment for calibration (e.g., large bubble burettes or electronic bubble
calibrators are not adequate). The equipment manufacturer generally offers
this service and recommends calibration at least annually.
The sampler(s) should be disinfected between sample locations. Isopropanol
is the agent of choice at this time. It can be easily purchased and treated, and
individual packets are available for purchase.
Excess cleaner (e.g., isopropanol) should be dried prior to its next use, and the
sieve holes should be inspected prior to proceeding. Then allow the sampler to
run for a couple minutes—at the new location—prior to taking the next sample.
Care should also be taken with the petri dish cover for the duration of the
sampling. A minimum precaution should be to place the cover face down on
a clean, smooth surface for the duration of the sampling. To assure a surface
is clean, wipe the surface with an alcohol swab prior to putting down the top
of the petri dish.
After the sample has been taken, replace the cover, seal or tape the edges
(e.g., laboratory Parafilm), label the petri dish, and store it with the agar side
down. Some laboratories prefer ice packs to accompany the samples. This
allows for the plates to be transported without growth occurring prior to
receipt at the laboratory, but excessive condensation in the plates may be
problematic. The laboratory chosen to perform the sample analyses should
be consulted prior to each scheduled sample collection for instructions
as to their in‑house procedures for packaging, shipping, and receiving. If
shipment to a laboratory is required, most laboratories require overnight
shipments. For samples that are shipped on a Friday, weekend, or holiday,
81
Viable Microbial Allergens
TABLE 5.4
Summary of Culture Media and Anticipated Growth Patterns
Culture Media
Malt extract agar
Rose Bengal agar
(suppresses bacteria)
Cellulose agar
R2Ac agar
Tryptic soy agar
Blood agar
MacConkey’s agar
Incubation
Period
Incubation
Temperature
fungi
fungi
1–2 weeks
1–2 weeks
RT
RT
Stachybotrys fungi
environmental bacteria
Thermophilic
actinomycetes and
Bacillus
pathogenic and
commensal bacteria
Gram negative bacteria
and E. coli
1–2 weeks
48 hours
48 hours
RT
RT
56°C
48 hours
35°C
48 hours
35°C
Predominant Growth
Note: RT = room temperature.
special arrangements should be made beforehand. Express delivery services
availability and time lags should be determined, and arrangements may be
needed with the laboratory for special deliveries.
When choosing a laboratory, consider in‑house procedures for sample
incubation. Suggested incubation for fungi is 10 to 14 days at room temperature with subsequent identification by genera. Some laboratories will perform a count within 5 to 7 days after receipt. Others feel the slower-growing
molds will take up to 14 days to grow, and a shorter incubation period may
result in incomplete counts and mold identification. The count can be off as
much as 10 percent, and an early count may also result in not identifying
some of the more important, slow‑growing molds (e.g., Stachybotrys).
Sample incubation times impact the laboratory turnaround time and
completeness of information, considerations which may vary depending on
each situation. For example, a quick turnaround is required, and the incubation period for a specific targeted mold type is five days. Some laboratories will not assess a sample until the full 14 days have passed. So, in some
cases, the investigator may want to locate a laboratory that will evaluate the
sample(s) earlier. Some do it routinely and this type of laboratory can be
found. See Figure 5.5 for petri dish growth samples.
Pathogenic molds will not readily grow on most of the media. They grow
best at higher incubation temperatures and require much longer incubation
periods, up to three weeks. If the pathogenic molds could grow at room temperature, on the nutrient media provided, the other fungi would likely overgrow the petri dish, and newly formed pathogenic mold colonies would not
be observed.
The recommended incubation for thermophilic actinomycetes is 55°C for
four days. On the other hand, Bacillus bacteria can be incubated within two
82
Indoor Air Quality: The Latest Sampling and Analytical Methods
(a)
(b)
(c)
FIGURE 5.5
Petri dish deposition using impaction samplers. Examples are: (a) impaction marks on agar, (b)
culture with count of 1761 CFU/minute on malt extract agar after five days of incubation, and
(c) excessive growth on malt extract agar after five days of incubation.
Viable Microbial Allergens
83
to four days along with the thermophiles on the same nutrient medium at
55°C, and Bacillus bacteria can be incubated in two days at room temperature
on the same nutrient media as the thermophiles or on a different medium.
The different incubation temperatures are important for identification of all
Bacillus genera. If Bacillus bacteria are amplified and contributing to the total
microbial allergens, the most likely Bacillus species to be found amplified
indoors would be those that grow at room temperature.
For quality control, some investigators collect a blank along with the air
samples. The blank may be an unopened or opened petri dish. The unopened
blank may provide information as to whether the nutrient medium has been
contaminated prior to sampling or during shipping. The opened blank may
give information as to the investigator’s sample handling procedures. Not currently a common practice, the submittal of blanks is gaining in popularity.
Procedural Summary
Determine a sampling strategy, when and where to sample. Get the appropri­
ate equipment, and collect the sample(s) with caution. Precautions should
be taken not to contaminate media by: (1) properly cleaning the equipment
between sample locations; (2) proper management of the sampling media;
and (3) proper shipping.
Collect each sample, label containers (e.g., alpha numeric), and log the
sample location details as well as air volume sampled or duration of sampling. Additional information the investigator may want to enter is observations (e.g., sample taken immediately under a recently opened ceiling
tile), environmental conditions (e.g., relative humidity and temperature),
air movement (e.g., directly in line with an air supply diffuser that was
blowing at the time of sampling or measured air movement 200 feet per
minute at sample location), and odors (e.g., a site identified as having strong
mildew odors).
Package all samples in a sturdy container. Some laboratories request special packing procedures (e.g., ship in Styrofoam™ container with ice pack).
Ship for overnight delivery to an analytical laboratory.
Diagnostic Sampling Methodologies
Oftentimes, it becomes necessary to identify the source of amplified microbes.
Either remediation of a suspected source has failed to rectify a problem, or
the environmental professional chooses to confirm suspect sources at the
time of the initial sample taking, possibly after obtaining the initial air sample results and prior to making recommendations. Bulk and surface sampling is the recommended approach.
84
Indoor Air Quality: The Latest Sampling and Analytical Methods
Sampling Strategy
Purpose is the focus when developing a sampling strategy. Bulk and surface
sampling may be performed for any of the following reasons:
• To confirm or deny a suspect source of mold growth
• To identify sources of potential airborne microbes
• To confirm adequate cleanup
If a surface has visible staining, the discoloration may or may not be molds.
Surface sampling can be performed not only to confirm or deny its presence but to identify the type of mold. A dark black stain that appears to be a
mold on a wall surface may be charred grease or shredded rubber, or a black
graphitelike material on the wall may be a specific identifiable mold.
Molds are often found growing on wet fiberglass duct insulation immediately after the cooling coils. This is a common finding, and surface sampling
is vital to confirm the presence of molds where expensive remediation may be
involved.
Duct‑cleaning services and some investigators confirm molds in the relatively dry ducting and use its mere presence to justify cleaning the air ducting. It is no surprise that these same people always do find molds in the
air ducts and subsequently require extensive duct cleaning. The investigator
should not rely on surface and bulk samples alone because
… bulk samples cannot replace air samples because the former have not
been found to accurately reflect past, future, or even current bioaerosols.7
Once air sampling has been performed and amplification of certain
molds confirmed, the investigator should locate the source. Cleanup can
be very expensive, and identification of the source can be vital not only
to limit the cleanup but to assure that the actual source has been located
and remediated.
After remediation and cleanup of an area, surface sampling may be performed to confirm adequate cleaning. This is a secondary approach after a
visual inspection has been performed and all surfaces appear to be clean.
Where to Sample
Once the purpose has been defined, the investigator performs a visual
inspection of the area or areas of concern. If microbial growth is apparent, a
sufficient number of samples should be taken to represent all suspect components. For instance, if wet duct insulation has a large surface area with
thick brown mudlike splotches, a black-green patch, and several white spots,
one of each of the three different sites should be taken.
If microbial growth is not apparent, the investigator may either perform
several random samples or identify suspect areas based on area activities,
Viable Microbial Allergens
85
interviews, and the presence of moisture/growth media. Custodial or maintenance personnel may have been observed working above ceiling tiles in
the complaint area. Carpeting and partition panels may harbor molds but not
have a visible presence. Settled water may be contaminated with microbes
but not have any visible evidence as to its presence.
When deciding where to sample, the investigator should focus on the following points:
• Microbial growth is influenced by temperature and humidity.
• Dissemination of microbial allergens is influenced by activities (e.g.,
vacuum cleaners may disperse molds into the air), the presence of
molds (e.g., excessive dust collection), and air movement over surfaces (e.g., inside air ducts).
Upon confirmation as to the presence of high moisture content in walls,
some investigators actually put a hole into the wall in order to take a sample
of a suspect microbial growth surface and, upon identification of its presence, spend great sums of money remediating wall spaces that contain mold
spores, with no evidence of airborne spores. Although it is possible to have
air movement within the wall spaces and entry of wall contaminants into
occupied spaces through wall penetrations (e.g., wall sockets), these considerations are rarely tested.
The greater the number of samples taken, the more reliable the statistical end product. Yet larger sample numbers are more expensive. All factors
should be taken into consideration.
What to Sample
Microbes can be found in or on almost anything. Thus the investigator should
be prepared to interpret findings prior to sampling. Taking samples without
a game plan can result in a conclusion with strange bedfellows.
Samples can be taken of surfaces or suspect bulk materials. Surface sampling may involve loose surface debris and dust, and bulk sampling may
involve a substrate and its component debris and dust. The substrate may be
a porous solid material (e.g., carpeting or fabric office partition), or it may be
a liquid (e.g., water in a drip pan).
Yeasts and molds may grow in flower pots. These are areas often overlooked. Where suspect, soils may also be sampled.
Sampling Supplies
The equipment needed for surface and bulk sampling is less involved than
air sampling. Although the equipment can often be purchased at a local
grocery or drug store, the analytical laboratory should be consulted prior to
obtaining supplies. They may prefer their own sterile supplies or may have
86
Indoor Air Quality: The Latest Sampling and Analytical Methods
developed detailed directions and protocols. Many laboratories will send
the appropriate supplies upon request.
Surface sampling is often done by wipe (i.e., swipe) sampling or dust collection. Wipe sampling is performed using a sterile swab that can be returned
to a sterile container after a sample is taken. In some cases, the container will
have a wetting solution in an ampoule that is broken to release a wetting
agent onto the surface of the swab (e.g., 3M Quick Swab). However, some
laboratories prefer the investigator use dry swabs.
Dust, debris, and soil can be collected in plastic ziplock bags, capped vials,
or filters (e.g., cassettes) with a suction device (e.g., air sampling pump).
Water samples can be collected in capped vials, and moist surface areas may
be sampled with a swab.
A sterile template is advisable for swipe sampling. Some laboratories
supply a prepackaged plastic 4‑inch by 4‑inch template. The template provides boundaries within which a sample may be taken and surface area
reported.
Bulk sampling requires a sterile container, cutting tool, and latex gloves.
Larger samples will require larger containers, and if an abundance of
microbes is anticipated, sterile containers may become a moot point.
Procedural Summary
Determine a sampling strategy, where to sample, and what to sample. Get the
appropriate supplies and collect the samples without cross-contaminating
each new sample. Cross-contamination may occur by unprotected hands and
uncleaned implements (e.g., template or utility knife).
Collect each sample, label containers (e.g., alpha numeric), and log the
sample location details as well as surface area or size/volume of the bulk
material. Additional information the investigator may want to enter is visible
surface area affected (e.g., visible coverage on approximately 20 square feet),
environmental conditions (e.g., wet duct insulation, high humidity, and temperature), and description of stained material (e.g., tea‑colored ceiling tiles).
Package all samples so cross-contamination, penetrations, and damage
cannot occur during shipping. Ship perishable samples by overnight delivery to an analytical laboratory.
Interpretation of Results
The interpretation of results is highly controversial. Attempts have been made
by various researchers and professional groups to set exposure limits for allergenic spores, but environments, exposure durations, predisposing health conditions, and limitations of viable sampling add fuel to an already heated topic.
87
Viable Microbial Allergens
TABLE 5.5
Concentrations of Viable Allergens in Agricultural Environments
Workplace Environment
Thermophilic Actinomycetes
Outside air
Domestic waste management
Farming (normal activities)
Farming (handling moldy hay)
Pig farms
Mushroom farms (composting)
Mushroom farms (picking)
Sugar beet processing
Cotton mills
10
1,000
—
1,000,000,000
1,000
10,000,000
100
100
100,000
Total Fungi
1,000
100,000a
10,000,000
1,000,000,000b
10,000
100
100
1,000
1,000
Mostly Aspergillus and Penicillium.
Mostly Aspergillus.
Excerpted from Crook, B.8
a
b
Office, agriculture, school, and residential environments will vary considerably in anticipated exposure levels and in tolerance. Anticipated exposures
to agriculture workers are quite high, whereas office exposures are generally
less than 200 CFU/m3. See Table 5.5.
Office personnel and agriculture workers are typically healthy adults, and
their exposures are limited to workday hours. Yet even in this group there
are people who are more sensitive to allergens than others (e.g., asthmatics). School children have more allergies than adults. They grow out of these
allergies as they get older, but they are exposed to all sorts of allergens in
their school environments. Residential exposures include infants, elderly
people, and adults with debilitating health conditions, and their exposures
may be ongoing, 24 hours a day, seven days a week. Setting one limit to
accommodate all is not feasible.
The other problem with establishing an exposure limit for viable microbial
allergens is that the count may not be representative of all microbial allergens.
All microbial allergens include viable, culturable, and nonculturable microbes.
The information derived from viable microbial allergens may be only a small
portion of the offending allergens. Although not always applicable, the information derived from viable microbial sampling often needs to be assessed by
other means. To date, the most recognized approach to defining environmental problems as they relate to microbial allergens is the assessment of genus
variability, a process that has as many approaches as there are investigators.
Genus Variability
Genus variability involves genus identification and percent of total components. The indoor complaint area is compared to the outdoor area and sometimes to a noncomplaint area as well. Where there is a shift in the percent of
88
Indoor Air Quality: The Latest Sampling and Analytical Methods
identified components in the indoor air versus the outdoor air, indoor amplification (or growth on a building material) is indicated. A shift in the percent
is interpreted in several different ways.
The most common approach is to assess percent of total microbial allergens. For instance, the outside air may contain 85 percent of Cladosporium,
10 percent of Alternaria, and 5 percent Penicillium, and the indoor air may contain 90 percent Peni­cillium, 8 percent Cladosporium, and 2 percent Altemaria.
This example, involving unrealistically limited numbers of mold spores in a
total count, is a good indicator that Penicillium molds are growing indoors.
Some investigators generate a graph of the more realistic 10 to 12 identified
molds and compare these. This approach is not as easy to assess as where the
top two or three identified molds are compared without the complex jumble
of all molds.
Some investigators do not perform a genus variability assessment where
the total count is low (e.g., less than 100 CFU/m3). A low colony count is
subject to considerable variability. The collection of only a few spores in a
small air volume can vary a lot due to natural variability of air samples and
sampling or analytical errors. The statistical variability due to these factors
has yet to be published for viable mold sampling methodologies.
Amplification is often considered where certain toxigenic molds are identified indoor, irrespective of that identified outdoors. Stachybotrys is one such
mold. Be wary, however, of declaring amplification where there is a single
colony of a given mold. A single colony may be an anomaly that occasionally
occurs in outdoor air samples as well.
The assessment may also be limited by the laboratory reporting techniques.
Most laboratories identify the more prevalent genera, up to a limited number
(e.g., five of the most numerous mold colonies). Some identify all recognizable genera on the basis of growth structure and patterns, whereas others
identify the most prevalent genera. Many will attempt to identify species
of Aspergillus as well (e.g., Aspergil­lus flavus). Other genera must be replated
for species determination. This involves more expense and culturing time
(e.g., an additional two weeks). A fungal colony may be declared as unidentifiable, or if it fails to produce sporulating structures in culture, is referred
to as a nonsporulating colony or mycelia sterilia. The latter means that the
mold is sterile and does not form fruiting bodies (e.g., reproductive spores)
in the particular nutrient media provided by the laboratory. The mycelia can,
however, be replated onto other media where they may grow and potentially
be identified. Due to recent concerns, most laboratories will also identify the
most common species of Stachbotrys (i.e., Stachybotrys chartarum). The same
interpretation process should apply for thermophilic actinomycetes and
Bacillus bacteria as well. Separate sample culture media and analytical techniques are required for bacterial isolation and identification.
Prior to 1999, ACGIH publications recommended numeric exposure limits.
These have since become obsolete, but some investigators persist in demands
for airborne exposure limits.
Viable Microbial Allergens
89
Airborne Exposure Levels
Reports indicate that outdoor spore counts routinely exceed 1000 counts/m3
and may average near 10,000 counts/m3 during warmer, more humid months.
In some parts of the country, the outdoor levels may exceed 20,000 counts/m3.
The levels vary throughout the day and only a percent of these are viable.
With rare exception, indoor levels of allergenic molds that are less than
100 CFU/m3 are not typically associated with complaints. Exceptions include
special environments, such as hospitals, where there are immune-suppressed
patients that must avoid any level of certain molds (e.g., Aspergillus flavus)
and people with life-threatening respiratory problems.
Some environmental professionals chose 200 CFU/m3 viable molds as the
minimum indicator for probable indoor exposure limits in environments
with a relatively healthy adult population (e.g., office buildings). The previous ACGIH recommended limits were even more permissive.
In 1986, the ACGIH recommended a limit of 10,000 CFU/m3 total fungi,
500 CFU/m3 for one genus of mold, and 500 CFU/m3 for thermophilic actinomycetes. In 1989, they recommended comparative sampling and stated that
the presence of thermophilic actinomycetes, typically associated with agricultural environments, is sufficient to indicate contamination.
While comparison sampling has become a sound scientific approach for
ascertaining amplification, viable sampling provides only a piece of the picture. An easily referenced standard for acceptable mold and bacteria spore
levels is not just over the horizon.
Bulk and Surface Sample Results
The laboratory reports bulk samples in terms of identified viable microbial
numbers per weight or volume of material. This is usually in terms of CFU/
gram or CFU/milliliter.
Surface sample results are reported based on the identified viable microbial numbers per surface area. This is typically done in terms of CFU/cm2
or CFU/inch2.
Although the numbers may appear quite high to an investigator (e.g.,
2,000,000 CFU/gram), there are currently no guidelines to assist in the
assessment of these levels. Poor numerical correlation exists between bulk
and surface sample results, although species identification of molds growing
on surfaces within buildings can be directly compared to species identified
in air samples. Thus the best use for the results is identification of probable
sources that result in amplification of allergenic microbes indoors.
For example, if there was 43 percent Aspergillus sydowii indoors and none in
the outdoor air sample, and 100 percent Aspergillus sydowii in a bulk sample,
the bulk sample location is immediately suspect of being the source or one
of the sources of amplified airborne mold spores. If the bulk sample had contained Aspergillus versicolor (and was not found in the air sample), the sample
site would not be suspect. This is where species identification can be helpful.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Although they may have the same mold types, surface area samples will
typically be in smaller numbers than those analyzed by weight. For instance,
duct insulation may have 2,140,000 CFU/gram (and 100 percent Penicillium)
with a surface level of 2 CFU/cm2. An attempt to interpret the numbers can
be a daunting task. However, it is clear that most of the contaminant is deep
within the porous surface of the duct insulation.
Helpful Hints
When taking short‑term samples, either use a stop watch, a timer with a
second hand, or an in‑line timer that will turn off the sampler. One‑ and
two‑minute samples that go over by 10 or 15 seconds can make a big difference in the calculated air volume and final results if not reported. If you go
over, either report the air volume on the basis of the time sampled in terms
of minutes and seconds or start over.
It is also distinctly possible, perhaps inevitable, that the investigator will
at some time poke his or her finger in the sterile nutrient agar. Once compromised, the plate should be discarded. Start over again.
As a level of confidence is reached, the investigator will typically choose
one sampler and stay with it. While this is a prudent practice, other methods
that may meet more expanded needs are constantly being improved and
refined. Many approaches are tried and true, but new technology emerges
every day. The investigator may follow the progress of new technology
through professional journals, conferences, and publications.
Summary
Viable microbial allergens include molds and spore‑forming bacteria. Yet
viable is the key word. All airborne microbial allergens may not grow on the
nutrient media used for air sampling. For this reason, a count is often questioned. The primary information the investigator needs to target is the comparative sampling (i.e., comparison of complaint, noncomplaint, and outdoor
samples). Then, too, if the sampling strategy and methodologies are poorly
planned and executed, the results can be difficult, if not impossible, to assess.
Diagnostic sampling can be invaluable if performed methodically with a
clear concept of what one is looking for. Sampling for sampling’s sake will
go nowhere.
Viable microbial sampling is best used in conjunction with pollen/fungal
spore counts. In one situation, the fungal spore counts had an elevated
Viable Microbial Allergens
91
anomaly the laboratory wanted to call Aspergillus/Penicillium. Two weeks
later as the viable results became available, the count was low and the
anomaly turned out to be oil droplets. Viable sampling does have a place in
obtaining information.
References
1. ICMSF. Microbiological Ecology of Foods. Academic Press, New York (1980).
2. ACGIH. Bioaerosols. ACGIH, Cincinnati, (1999), p. 19–6.
3. Crissey, J.T., H. Lang, and L. Parish. Manual of Medical Mycology. Blackwell
Science (1995), pp. 190–201.
4. Al‑Doory, Y., and J. Domson. Mould Allergy. Lea & Febiger, Philadelphia (1984),
pp. 36–37.
5. Jaeger, Deborah, L., M.S. et al. Microbes in the Indoor Environment. PathCon
Laboratories, Norcross, Georgia (1998).
6. ACGIH. Bioaerosols. ACGIH, Cincinnati (1999).
7. Ibid, pp. 12–3.
8. Crook, B., and J. Lacey. Airborne Allergic Microorganisms Associated with
Mushroom Cultivation. Grana. 30:445 (1991).
6
Pathogenic Microbes
In indoor air quality investigations, pathogenic microbes are disease-causing
fungi and bacteria to which building occupants are most likely exposed.
Although a proactive approach to problem identification is desirable, exposures to pathogens and toxic microbes are a rare concern in indoor environments unless a large number of associated illnesses are reported.
Sampling requires lengthy culture times, complicated by the presence of
other environmental, nonpathogenic microbes that may mask and prevent
identification of the pathogen by over-growing the culture medium. Then,
when a suspect colony is isolated, additional time is required to perform
more extensive, complicated analyses/cultures in order to confirm its identity and, in many cases, to determine the species and strain.
Whereas many of the pathogens are potentially lethal, the time required
for identification is frequently not practical. For this reason, the presence of a
pathogen is often assumed where patients are symptomatic or reacted upon
later. Typically, health professionals attempt to isolate the source environment through studying sick patients’ habits and environmental associations,
trying to recreate a common denominator for an observed epidemic.
Although pathogenic diseases are frequently occupation and area dependent, the greatest attention to pathogen spread occurs in hospitals. An
infected patient aerosolizes (e.g., coughs or sneezes) viable pathogens, and
immune-suppressed patients are particularly susceptible to aerosolized
pathogenic and normally nonpathogenic microbes. Immune-suppressed
patients include those with AIDS, organ transplants, chemotherapy treatments, and diabetes. Operating rooms and invasive diagnostic testing areas
are possibly involved. Infants and the elderly can be compromised.
Those weakened by living conditions (e.g., the homeless) and inadequate
nourishment (e.g., Somalians) exhibit an enhanced susceptibility to pathogens. Then, too, some pathogenic microorganisms are capable of causing
disease in healthy individuals under special circumstances. Contaminated
intravenous solutions and hospital implements provide an easy avenue for
entry. Puncture wounds in contaminated environments are fertile soil, and
damaged tissues propagate invasive challenges. Opportunity for pathogenic
assaults is subsequently dependent upon the environment.
Some pathogens multiply in air handlers and water reservoirs. Many are
contained within environmental dust. The problems are rarely identified
93
94
Indoor Air Quality: The Latest Sampling and Analytical Methods
prior to the spread of disease to others associated with the dispersing mechanism. Sampling is generally requested after a problem has arisen. Proactive
sampling in environments where specific pathogens may thrive is indicated.
As invasion and amplification require viable pathogens, the best sampling
is for viables. However, viable samples require lengthy culture times, long
periods of time not always prudent in a potentially lethal environment.
Methods are available that can identify some pathogens rapidly and accurately. However, these methods identify nonviable and noninvasive microbes.
They are limited, and the results are sometimes difficult to interpret. Yet the
information is provided herein should an investigator require rapid processing until more reliable information can be provided at a later date.
Airborne Pathogenic Fungi1–3
Pathogenic fungi are those fungi that cause disease through inhalation of
airborne spores (e.g., Histoplasma capsulatum) as well as potentially causing
disease in immune-suppressed patients and individuals with skin surface
damage (e.g., Aspergillus flavus). Skin surface damage may include wounds,
open sores, cuts, abrasions, burns, and dry cracks. Symptoms of fungal disease range from localized surface discomfort to whole body invasion, and
occasionally death.
The primary focus of this section is to discuss the airborne fungi that can
invade and cause death. Only the principal pathogenic molds are discussed.
Those that are infrequently or not typically found in the United States may
require additional research, strategy, and sampling development. The following information should provide direction and guidance to addressing
potentially lethal environmental situations.
Disease and Occurrence
Understanding the diseases caused by specific pathogenic fungi and regions/
areas where they primarily occur is necessary to determine a need for sampling. At the same time, however, the environmental professional must not be
limited by this information. An outbreak may occur when least expected.
Aspergillus
Several species of Aspergillius, primarily Aspergillus fumigatus and flavus,
can cause a disease commonly referred to as aspergillosis. As the genus
Aspergillus is one of the more common fungal spores found in air monitoring,
the pathogenicity is minimal, unless an individual is immune suppressed or
95
Pathogenic Microbes
has a debilitating illness. The initial symptoms may be localized to the lungs,
ears, or perinasal sinuses. Once the fungus has found a place to grow, the
hyphae may grow into the bloodstream to deposit spores to be disseminated
to other parts of the body. The result may be the formation of abscesses or
granulomas in the brain, heart, kidney, and spleen.
As Aspergillus fumigatus and flavus thrive in immune-suppressed patients,
the greatest areas of concern are in the hospitals, clinics, nursing homes, and
hospices. Immune-suppressed patients include AIDS patients, organ transplant patients (e.g., heart transplants), premature infants, and radiologically
treated leukemia patients. Invasive diagnostic suites and operating rooms
are particularly critical. The presence of even low levels of the invasive forms
of certain Aspergillus species can be deadly. The hospitals seek to control
these environments. See Table 6.1 for historic outbreaks.
Some studies have included several fungal species to the list of potential
invaders. One such study includes the following:4
• Aspergillus fumigatus
• Aspergillus flavus (also producer of the carcinogen aflatoxin)
• Aspergillus niger
TABLE 6.1
Historic Outbreaks of Nosocomial Aspergilliosis
Number of
Patients
Type of Disease
7
(not identified)
32
pneumonia/sinusitis
respiratory patients
10
invasive pulmonary
disease
invasive pulmonary
disease
invasive pulmonary
disease (2) and
colonization (1)
invasive pulmonary
disease with one
dissemination
invasive pulmonary
disease with one
dissemination
immunosuppressed (7),
malignancy (2), elderly (1)
—
recent construction and
defective air conditioner
building construction
and defective AHUs
and colonization
road construction and
defective air conditioners
building construction
renal transplants
hospital renovation
acute hematological
wet fireproofing and dust
on false ceiling;
malignancy, neutropenia
pigeon excreta external
through the air intake
9
3
8
4
Host
bone marrow transplants
renal transplantation,
immunosuppressive drugs
Environmental Factors
Note: Numbers in parentheses are breakdown of host patients from first column.
Source: Cross, A.S. Journal of Nosocomial Infection. 4(2):6–9 (1985). With permission.
96
•
•
•
•
•
•
•
Indoor Air Quality: The Latest Sampling and Analytical Methods
Aspergillus terreus
Pseudallescheria boydii
Fusarium spp.
Mucoraceae spp.
Phoma spp.
Alternaria spp.
Penicillium spp.
Other studies include Zygomycetes and Rhizopus.5, 6 Most agree, despite the
failed concurrence of opinions, that Aspergillus fumigatus and flavus are the
predominant fungal spores of concern in hospitals. The other species should
be considered “potentially invasive” by the environmental professional.
There are a few occupational exposure concerns regarding the genus
Aspergillus as well. Aspergillosis was first described by an Italian in the 1700s
as an occupational disease of people who handled grains and birds.
This concern, however, has lost its significance in modern times. As the
fungus grows best on compost and damp organic matter, farmers and field
workers are a potential risk for high airborne exposures to Aspergillus.
Histoplasma capsulatum
Histoplasmosis, caused by inhalation of the mold spores of Histoplasmoa
capsulatum, results in a variety of clinical manifestations. Primary histoplasmosis is a common, region-oriented, benign disease of the lungs involving a
mild or asymptomatic pulmonary infection with a cough, fever, and malaise.
Chronic cases may go on to experience a productive cough, low-grade fever,
and a chest X-ray showing cavitation. As the cavitation resembles tuberculosis, however, many cases are misdiagnosed. Then, a small percent (less than
1 percent of all cases) of those showing symptoms develop in the progressive
form that can be lethal.
Progressive, systemic histoplasmosis is less common. It is characterized
by emaciation, leukopenia, secondary anemia, and irregular pyrexia. There
is frequently ulceration of the naso-oral-pharyngeal cavities and intestines,
with generalized infection of the lymph nodes, spleen, and liver.
There have been reports of Histoplasma capsulatum related chronic meningitis in nonimmune-suppressed hosts, and some have speculated that the
fungus also contributes to persistent or recurrent carpal tunnel syndrome.8, 9
Symptoms in immune-suppressed patients are highly variable, and the fungus is generally associated with other pathogens.
Within the United States, Histoplasma capsulatum is endemic in the Central
Mississippi Valley, Ohio Valley, and along the Appalachian Mountains.
See Figure 6.1. Other endemic areas include sections of South America and
Central America, and there are occasional outbreaks in various parts of
the country and world. It is thought that the spores become airborne and
Pathogenic Microbes
99
Sampling should include soil and dust samples from occupational or residential environments in regions endemic with Coccidioides immitis. With a
few minor exceptions, the sampling methodology for this fungus is similar
to that of Histoplasma capsulatum.
Cryptococcus neoformans
Cryptococcus neoformans attacks the central nervous system, producing subacute or chronic meningitis. It may also impact the lung tissue and cause
low-grade inflammatory lesions that may be mistaken for tuberculosis or a
neoplasm. Occasional cases arise whereby the fungus gives rise to localized
nodular lesions of the skin or generalized infections with lesions of the skin,
bones, and viscera.
Rare in healthy adults, Cryptococcus neoformans varieties neoformans and
gattii are reported to be the cause of death in 6 percent to 10 percent of the HIV
patients. Thus they are among the most common AIDS-related, lethal mycoses.11 These strains have been known to cause blindness in AIDS patients
and are the foremost cause of central nervous system infections in the same.
Diabetics, cancer patients, and recipients of organ transplant patients are at
risk of generalized infection. Fungal infections range from 5 percent in recipients of kidney transplant patients to as high as 40 percent among recipients
of liver transplants.12
The most commonly reported source of Cryptococcus in urban environments
is dust and debris associated with pigeon droppings. There are also numerous reports from Australia that the source of infections can be attributed to
certain species of Eucalyptus (e.g., river red gum and forest red gum).13
Prior to an incident or outbreak, routine sampling for fungi, identifying
Cryptococcus neoformans, is indicated especially in areas where immunesuppressed patients may be compromised the greatest (e.g., operating
rooms). Particular attention should be given to the air handler systems (e.g.,
growths occurring beyond the filtration devices) supplying the operating
rooms, minor surgery suites, and invasive diagnostic rooms.
Cryptococcus neoformans occurs in cultures in the form of round, yeastlike
cells, surrounded by a large gelatinous capsule that is thought to contribute
to its ability to resist phagocytosis and bypass the initial body defenses.
Although they measure 5 to 20 microns in diameter when in tissues, the cells
measure 2 to 5 microns in culture media.
Other Pathogenic Fungi
Most of the other fungi which have not been mentioned are either nonpathogenic, rare occurrences of disease in the United States, or rarely infectious
through inhalation. For easy reference, potentially opportunistic and rarely
pathogenic airborne fungi are identified in Table 6.2 along with other health
effects of the more common airborne fungi. This information is intended to
humidifier fever
humidifier fever
–
X
X
X
X
X
humidifier fever and
sauna taker’s lung
–
wine grower’s lung
–
hot tub lung, moldy
wall hypersensitivity
–c
X
–
X
X
X
X
X
X
X
X
X
X
X
X
Bipolaris
Botrytis
Chaetomium
Cladosponum
Curvularia
Epicoccum
Fusarium
Hypersensitivity
Pneumonitis
X
X
X
Allergenic
Acremonium
Altemaria
Arihrinium
Aspergillus
A. fumigatus
A. flavus
A. niger
A. versicolor
A. sydowii
Aureobasidium
Fungus
Pathogenic
opportunisticb
rare
one rare species
(Cladosporium carrionii)
rare
–
X
–
aspergilliosis & oppor.b
aspergilliosis & oppor.b
swimmer’s ear
–
potentially oppor.b
–
rare
rare
potentially oppor.
Health Effects of the More Common Airborne Fungi.14–16
TABLE 6.2
X
–
several antibiotics
X
X
X
–
X
X
X
X
X
–
antibiotic cephalosporins
X
–
Potentially Mycotoxin(s)
require high moisture
grows on cellulose
–
some xerophilic species
grows at 37°C or higher
grows at 35°C or higher
–
–
–
where moisture accumulates
especially in bathrooms and
kitchens, under window sills,
liquid waste (e.g., sewage)
–
”noble rot” wine grapes,
damages plants
damp sheetrock paper
growth range: 0–32°C;
moisture: >0.85
–
low temperature growth range:
4°–45°C; moisture: >0.86 d
moisture: > 0.86d
Possible Comment(s)
100
Indoor Air Quality: The Latest Sampling and Analytical Methods
X
X
X
X
X
X
X
–
–
X
–
X
X
X
X
X
X
X
–
X
X
X
Torula
Trichoderma
Ulocladium
–
–
–
–
–
–
potentially oppor.b
–
rare
rare
rare
rare
rare
–
X
–
X
antibiotic penicillin
antibiotic griseofulvin
X
X
X
–
X
–
–
–
Note: – = either not reported, not confirmed, or not known.
a Humidifier fever, malt worker’s lung, wood trimmer’s disease, straw hypersensitivity, and farmer’s lung.
b Opportunistic with weakened conditions and immune-suppressed individuals.
c Allergic fungal sinusitis.
d Grows at 37°C or higher.
–
X
–
X
X
X
Geotricum
Mucor
Nigrospora
Penicillium
P. mameffei
P. chrysogenum
P. griseofulvum
P. brevicompactum
P. fellutanum
P. viridicatum
Rhizopus
Stachybotrys
–
moisture: >0.90d
–
moisture: >0.78
–
–
_
–
–
–
moisture: > 0.94d
moisture: > 0.94d; grows on
cellulose
grows on cellulose
grows on cellulose
–
Pathogenic Microbes
101
102
Indoor Air Quality: The Latest Sampling and Analytical Methods
provide a quick, easy reference, not to burden the reader with scare tactics.
Should the occasion arise that a common mold is suspect of causing disease,
additional research is recommended.
Sampling and Analytical Methodologies17, 18
Although many are drought resistant, most pathogenic fungi do not retain
their viability during air sampling or may be overgrown on the nutrient
media by other fungi, masking the presence of the slower growing pathogens. However, where air sampling has been performed for allergenic viable
fungi, a pathogen may inadvertently become identified. The methodologies for air sampling for allergenic molds are detailed in Chapter 5, “Viable
Allergenic Microbes.” The most commonly identified pathogenic fungi found
during routine viable allergenic mold sampling is Aspergillus.
Aspergillus fumigatus is thermotolerant and will grow at temperatures of
45°C, or higher, which is an extreme temperature for most allergenic fungi.
Culturing a viable allergenic mold sample at this temperature serves as a
means for limiting other fungi from growing and overgrowing the Aspergillus
fumigatus. On the other hand, the least likely to be identified during viable
allergenic mold sampling are Histoplasma capsulatum, Coccidioides immitis,
and Cryptococcus neoformans.
The method for Histoplasma capsulatum and Coccidioides immitis is specific
for these pathogens only. Sampling involves the collection of settled dust
from surfaces and placement in a sterile container. Yet due to the analytical
time and cost, proactive sampling is rarely performed. Although some specialized mycology labs offer environmental screening for fungal pathogens
at a modest cost, in one recent laboratory quote, the minimum analytical
cost was $4000. The reason for the high cost is that analysis involves injecting the sample(s) into laboratory rodents, organ extraction, and culturing
the isolated organism, and the laboratories require at least 10 samples be
handled in like fashion. This is included in the minimum charge. Another
limitation to this process is time. The laboratory turnaround is at least two
months. Given all the methodology limitations to identifying Histoplasma
capsulatum and Coccidioides immitis in occupied spaces, sampling is generally performed only where disease is already known. Where the extent and
impact of the associated disease is increasing, and corrective actions have
been initiated, the investigator may take a set of samples prior to corrective controls and another set after remediation in order to confirm adequate
measures have been taken. Once again, the time delay is unavoidable, and
by the time the results are known, the building will most likely have long
since been reoccupied.
Cryptococcus neoformans also requires a dust sample and is difficult to
identify. As with Histoplasma capsulatum, sampling involves the collection of
settled dust from surfaces and placement in a sterile container. After sample
collection, the method varies. Only one sample is required. It is serial diluted,
Pathogenic Microbes
103
plated on special nutrient agar at the laboratory, and cultured at 37°C. Once
identified, species and sometimes variety (e.g., Cryptococcus neoformans, variety neoformans and variety gattii) determinations require additional plating
(e.g., slant specialized nutrient agar in test tubes). This requires a trained
laboratory technician and may involve several steps with additional culturing, plating, replating, and stains. These additional efforts may also be time
consuming and expensive.
Interpretation of Results
There are no definitive guidelines for interpretation of results. Where a pathogenic fungus is region dependent, baseline levels in symptom free areas in
endemic regions may provide a means for dose comparisons. Currently there
are no widely published findings nor recognized research studies that have
identified baseline levels and suggested response limits.
For immune-suppressed patients, any level of exposure may be potentially
lethal. Thus its confirmed presence in a hospital treatment area or association with medical implements should constitute reason for concern. The
source should be found and remedied, and medical implements cleaned.
With immune-suppressed patients, there has been no determination as to an
acceptable level. Many health/environmental professionals, when assessing
sensitive environments, express concern at any level of identification and
remediate to zero detection.
Airborne Pathogenic Bacteria19–21
Most airborne bacteria are nonpathogenic. The most numerous bacteria are
the environmental bacteria, whereas indoor bacteria that are associated with
humans are referred to as commensal bacteria. Pathogenic bacteria are not
common and sometimes difficult to isolate.
Most of the pathogenic bacteria indoors occur when they are aerosolized
from soil, water, plants, animals, and people, but outdoor exposures may also
occur. The latter are generally associated with windblown dust. Airborne
pathogenic bacteria usually infect the respiratory tract.
Enormous numbers of moisture droplets are expelled during coughing, and
smaller amounts are expelled through talking. A single sneeze by an infected
person may generate as many as 10,000 to 100,000 bacteria. On the more positive
side, most bacteria do not survive for long once they have become airborne.
Each of the pathogenic bacteria has its own distinct survival adaptation
that permits it to survive long enough to invade its target host. The bacteria
Legionella is highly resistant to acids. The thicker walled, Gram-positive bacteria (e.g., diphtheria) are resistant to drying, and pathogenic Bacillus anthracis
104
Indoor Air Quality: The Latest Sampling and Analytical Methods
forms protective spores. The more prominent airborne pathogenic bacteria
found within the United States, those posing the greatest concerns in the
occupational and indoor air environments, are discussed herein.
Pathogenic Legionella 22–23
Diseases caused by the water inhabiting bacterial genus Legionella are estimated by the Centers for Disease Control at between 25,000 and 100,000 per
year in the United States alone. Collectively, these diseases are referred to as
“legionellosis” (e.g., Legionnaires’ disease and Pontiac fever).
There are 34 known species of Legionella and 50 known serogroups.
Although many of the species have not been implicated in human disease,
Legionella pneumophila, Serogroup 1, is the most deadly, most frequently
implicated form associated with Legionnaires’ disease. The latter Serogroup
1 and many of the others are frequently found in all environments and water
reservoirs. Their presence alone is not sufficient to constitute a threat.
Virulence is related to the following:
•
•
•
•
•
•
•
•
•
•
•
•
Species and serogroup
Total amount of viable bacteria in a water reservoir
Aerosolization of contaminated water
Distribution of aerosolized droplets to human hosts
Cooling towers and evaporative condensers—least potential
Water heaters and holding tanks
Pipes containing stagnant water
Faucet aerators
Shower heads
Whirlpool baths
Humidifiers and foggers—highest potential
Reduced host defenses
Other sources of Legionella have been identified in unique environments.
In one case, an outbreak was tracked back to the misting of produce in a
Louisiana grocery store.24 Another involved a five patient outbreak that was
linked to the aerosol from a decorative fountain associated with a private
water supply in a hotel in Orlando, Florida.25
Warm water reservoirs provide the greatest potential for amplification of
the viable organisms. Viable organisms have also been isolated from stagnant pools, lakes, and puddles of water.26 An example of a highly virulent situation is the presence of Legionella pneumophila in large amount, aerosolized
and distributed from a warm humidifier into the living environment of an
immune-suppressed elderly patient.
Pathogenic Microbes
105
Although Legionnaires’ disease is primarily a disease of the elderly, it may
impact younger patients whose health has been compromised and immunesuppressed patients (e.g., AIDS patients). In a healthy adult of working age,
infections are usually asymptomatic and may in some cases result in mild
symptoms of headache and fever. In the elderly, prior to the onset of pneumonia, intestinal disorders are common, followed by high fever, chills, and
muscle aches. These symptoms progress to a dry cough and chest/abdominal pains. Where death occurs, it is typically due to respiratory failure. Death
occurs to only 15 percent of the less than 5 percent of the exposed individuals
showing disease that develops within three to nine days of exposure.
Pontiac fever is not quite so virulent. Within two to three days of exposure,
approximately 95 percent of all exposed individuals develop short-term flulike symptoms.
The Legionella bacterium is a thin, Gram-negative rod with complex nutritional requirements. A unique characteristic that is used in isolating the
genus is its ability to survive at pH 2.
Sampling and Analytical Methodologies for Legionella
Legionella pneumophila is fragile. Once aerosolized and dehydrated it loses its
viability. For this reason, air sampling is unreliable and not recommended.
Microbe damage and loss of viability may result in diminished counts.
Water sample collection procedures have been developed. They are considered more reliable and a means for interpreting the results has been
developed. Whenever possible, 1 liter of water should be collected in a sterile
container. Screw-capped, plastic bottles are preferred collection containers.
If the water source has recently been treated with chlorine, neutralize the
sample(s) with 0.5 milliliters of 0.1 N sodium thiosulfate. Several samples
should be taken from suspect/potential reservoirs.27
Sometimes 1 liter of water cannot be collected. Collect as much as is feasible and place it in an appropriately sized container. A 1-milliliter sample
may evaporate from or become irretrievable from a 1-liter container. Where
a sample is taken from a faucet or showerhead reservoir, available water is
minimal. In such instances, the reservoir should be swabbed with sterile
swabs (e.g., polyester medical swabs with a wood stick), contained within a
sterile enclosure. Upon sampling, each sample swab should be submerged in
a small amount of water from the source outlet (e.g., shower, faucet, etc.).
Upon completion of sample collection, all samples should then be sent by
overnight freight to a laboratory for analysis. If this is not possible, the samples should be refrigerated until they can be processed. Otherwise, avoid
temperature extremes both in storage and shipping.
At an experienced laboratory, the known aliquots of collected water sample
will be plated onto nutrient medium and cultured for up to three weeks. The
nutrient medium of choice is enhanced, buffered-charcoal yeast extract agar.
Prior to the plating, many of the samples are acid-treated for 15 to 30 minutes
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Indoor Air Quality: The Latest Sampling and Analytical Methods
then neutralized. Most of the other non-Legionella microbes are destroyed,
and the Legionella, having retained its viability, grows unrestricted.
The plates are incubated at 35°C and examined daily for 10 days. Legionella
bacteria are slow growing organisms, and colonies that develop early are not
likely to be Legionella bacteria. Sometimes, where there are excessive growths,
a determination may be made within a few days. Otherwise, the growth may
not appear for three weeks. Results are reported in terms of organisms per
milliliter of water.
Interpretation of Results
Researchers have developed exposure action levels for contaminated water.
These levels are based upon extensive experience and field studies. They
determined the levels of organisms present in various water sources where
Legionnaires’ disease was known and where it was not a reported problem. The data was compiled and numbers compared. It is from these studies
that the action levels were created in order to anticipate and avoid costly
outbreaks. These suggested limits are provided within Table 6.3. They are
intended to be used as guidelines only.
The action levels are 1 through 5. Action Level 5 requires the greatest
amount of care (e.g., immediate cleaning or biocide treatment). Each suggested action includes the preceding actions as well. The minimum recommendation for Action Level 1 is the review of routine maintenance programs
as recommended by equipment manufacturers. Action Level 2 is a follow-up
review for evidence of Legionella amplification. Action Level 3 represents
low contamination, yet elevated levels of concern. A review of the premises
for direct and indirect bioaerosol contact with occupants and their health
risk status is recommended. Where outbreaks may become possible, Action
Level 4 suggests cleaning or biocide treatment of the equipment. For suggested remedial actions details, see Table 6.4.
TABLE 6.3
Suggested Remediation Action Criteria Levels for Legionella
Legionella Organisms
per Milliliter
<1
to 9
to 99
to 999
>1000
Action Levels
CT/EC
1
2
3
4
5
Potable Water
2
3
4
5
5
Humidifier/Fogger
3
4
5
5
5
Note: CT/EC = Cooling towers and evaporative condensers.
Source: From Morris, G., et.al., Legionella Bacteria in Environmental Samples: Hazard
Analysis and Suggested Remedial Actions (Technical Bulletin 1.5), PathCon
Laboratories, Norcross, Georgia (1998). With permission.
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Pathogenic Microbes
TABLE 6.4
Suggested Remedial Response Actions23
Action Level
Suggested Remedial Response
1
Review routine maintenance program recommended by
the manufacturer of the equipment to ensure that the
recommended program is being followed. The presence
of barely detectable numbers of Legionella represents a
low level of concern.
Implement Action 1 and conduct a follow up analysis
after a few weeks for evidence of further amplification.
This level of Legionella represents little concern, but the
number of organisms detected indicates that the system
is a potential amplifier for Legionella.
Implement Action 2 and conduct a review of premises for
direct and indirect bioaerosol contact with occupants and
health risk status of people who may come in contact with
the bioaerosols. Depending on the results of the premises
review, action related to cleaning or biocide treatment of
the equipment may be indicated. This level of Legionella
represents a low but increased level of concern.
Implement Action 3. Then, cleaning or biocide treatment of
the equipment is indicated. This level of Legionella
represents a moderately high level of concern, since it is
approaching levels that may cause outbreaks. It is
uncommon for samples to contain numbers of Legionella at
this level.
Immediate cleaning or biocide treatment of the
equipment is clearly indicated. Conduct post-treatment
analysis to ensure effectiveness of the corrective action.
The level of Legionella represents a high level of concern,
since it poses the potential for causing an outbreak. It is
uncommon for samples to contain numbers of Legionella
at this level.
2
3
4
5
Source:
From Morris, G., et. al., Legionella Bacteria in Environmental Samples: Hazard Analysis and
Suggested Remedial Actions (Technical Bulletin 1.5), PathCon Laboratories, Norcross, Georgia
(1998). With permission.
Helpful Hints
Legionella may be hidden and amplified within the cells of other microorganisms (e.g., protozoa). Thus a negative result does not necessarily indicate the
environmental source of a sample is free of Legionella. In such cases, the environmental professional should comment that low levels are an indication of
“low risk.” There are no absolutes.
The occurrence of a potential misdiagnosis of disguised, elevated levels
has led to a choice not to sample by some environmental professionals.
However, this choice may potentially result in not identifying those that
are elevated.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
In a 1991 incident involving a Social Security Office Building in Richmond,
California, two people died of Legionnaires’ disease. The outbreak involved
10 cases and created considerable negative publicity. On March 13, 1995, the
U.S. Department of Justice settled the case rather than go to trial. The amount
of the settlement was not disclosed, though it was apparently substantial. A
key question in the case was, “Does the policy of not testing, the waiting for
cases of Legionnaires’ disease to occur, provide a reasonable standard of care?”28
Another incident involving exposures in a Jacuzzi on a cruise ship
occurred in 1994. A more recent event involved misting of grocery produce
and a link to Legionnaires’ disease. Each of these incidents may have been
avoided had prior sampling been performed, elevated levels identified, and
the sources remediated.
The criteria levels described above were developed by a laboratory that
maintained a stringent quality assurance program, including in-house proficiency testing of the laboratory personnel to insure accuracy and reproducibility. The interpretative value of these data may not be applicable with
quantitative values from other laboratories that do not have similar quality
standards.
Other Pathogenic Bacteria
This section excludes Legionella pneumophila. These other “airborne pathogenic bacteria” of potential concern to the environmental professional are
not as well-studied yet still deserve attention.
Disease and Occurrence of Prominent Airborne Pathogenic Bacteria
As they may not be identified during air or diagnostic sampling, disease or
the chance presence of pathogenic bacteria in a routine bioaerosol air sample
may be the only means for suspecting its presence in a given environment.
In alphabetical order, typical disease and occurrence of airborne pathogenic
bacteria frequently posing a concern are herein discussed.
Bacillus anthracis29, 30
The genus Bacillus includes spore-forming, rod-shaped bacteria that require
oxygen to grow. Although there are numerous species, only Bacillus anthracis
is known to be lethal to man. Many species have a commercial use in insect
control in the agriculture and forest industry. Although Bacillus anthracis is
the only deadly Bacillus, other forms may be opportunistic. Some species of
Bacillus and several species of Clostridium share the commonality of being
the only pathogenic, spore-forming bacteria. However, Bacillus anthracis may
cause disease through airborne transmission.
Mostly a disease of lower animals, Bacillus anthracis is transmissible to
man via the skin, alimentary tract, and respiratory tract. Disease in man
is typically an occupational disease associated with butchers, shepherds,
Pathogenic Microbes
109
herdsmen, and handlers of hides, hair, and fleece. During World War I,
anthrax-contaminated articles (e.g., shaving brushes) from Asia and South
America provided a source for infection. Currently, reports of anthrax disease come from Haiti and Zimbabwai.31 The primary concern is for airborne
exposures that result in pulmonary anthrax.
Pulmonary anthrax is due to inhalation of the microorganisms from the
air. Although uncommon, it is the most dangerous. It occurs occupationally
among those who handle/sort wool and fleece where the spores are floating
in the air from the infected material. It is characterized by symptoms of pneumonia that frequently becomes fatal septicemia. The dose-response is low.
Research indicates that only a few inhaled spores are required to produce disease. Immunization is possible, and infections are treated with antibiotics.
During World War II, Bacillus anthracis was researched heavily due to its airborne pathogenicity and resistance of the spores to drying. An effort was made
to develop drug-resistant strains, but it is not clear as to their success. They did,
however, find that the spores can remain viable in soil for as long as 60 years.
Bacillus anthracis is also a hazard to textile workers working with imported
animal hair. The primary concern may be airborne exposures, but the most
likely source of infection is through the skin.
The genus Bacillus is characterized by Gram-positive rods measuring 4.5 to
10 microns in length by 1 to 1.25 microns wide. They grow well on all common nutrient media, most rapidly between the temperatures of 41°C and
43°C in aerobic conditions. Spores can be destroyed by any of the following
methods:
• Boil for 10 minutes.
• Heat at 140°C for three hours under dry conditions.
• Disinfect with 3 percent hydrogen peroxide for one hour or with
4 percent potassium permanganate for 15 minutes.
Corynebacterium diphtheriae32
Only one species of Corynebacterium is an airborne pathogen. That is
Corynebacterium diphtheriae, the cause of diphtheria.
Diphtheria results from airborne exposures to the bacterium. Coryne­
bacterium diphtheriae enters the body via the respiratory route, lodging in the
throat and tonsils. Death may result from suffocation by blockage of the air
passages and by tissue destruction from the toxin involved.
Occasionally, it has affected the larynx, resulting in membranous croup, or
the nasal passages, causing membranous rhinitis. Diphtheria infections of
the conjunctiva and of the middle ear are less common, and cutaneous or
wound diphtheria is only occasionally observed. However, wound diphtheria may be serious, resulting in a systemic infection. Systemic infections
can severely affect the kidneys, heart, and nerves. Primary infection of
the lungs and diphtheritic meningitis has been observed on rare occasion.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Thus most of the concerns for the diphtheria bacillus would be in hospital
environments.
Corynebacterium diphtheriae are generally described as Gram-positive rods
with irregular staining responses. The ends of each rod are swollen and
respond greatest to staining, a characteristic unique to the genus. The bacteria measure 1 to 6 microns in length and 0.3 to 0.8 microns in width.
Mycobacterium tuberculosis33,34
Mycobacterium tuberculosis has three varieties (e.g., hominis, bovis, and avian).
The Mycobacterium tuberculosis variety hominis is highly infectious via airborne transmission of the disease. Not only are there different varieties, but
there are different strains.
Resistance to drug treatment occurs in vitro and in vivo. In the infectious
stage, drug resistance is more common with the Mycobacterium tuberculosis
than other pathogenic bacteria because of the extended, lengthy antibiotic
treatments required to fight the disease. Their persistence allows greater
chances for mutated strains to develop.
Tuberculosis is one of the most important communicable diseases in the
world, affecting more than 50 million people. In the United States, more than
50,000 new cases are reported annually, and 10,000 resultant deaths occur
per year. However, disease does not always develop in all those who have
been exposed. There is a possible dose–response relationship.
Potential transmission occurs in public places and hospitals, typically by
airborne droplets of contaminated sputum. Other modes of infection (e.g.,
genitourinary tract, conjunctiva of the eyes, skin, and alimentary tract) are
less common.
Bacteria-laden droplets and dust particles are inhaled, settle in the lungs,
and grow. In an individual with low resistance, an infection occurs. Extensive
destruction and ulceration of the lung tissue progresses to other parts of the
body, predominately the spleen, liver, and kidneys. If not controlled by antibiotics, death may result.
The tuberculosis bacteria are “acid-fast” rods, measuring 2 to 4 microns in
length 0.3 to 1.5 microns wide. Specialized enriched media and aerobic conditions are required for growth and isolation of the bacillus. The optimum
temperature for growth of the mammalian varieties is 37°C with a range of
30°C to 42°C.
Various Genera of Pseudomonas35, 36
Pseudomonas includes more than 30 species that are found in water, soil, and
compost. Of the many species, there are only a few pathogenic types.
The most widely known pathogenic form is Pseudomonas aeruginosa (also
referred to as Pseudomonas pyocyanea). They grow readily on all ordinary culture mediums and most rapidly between the temperatures of 30°C and 37°C.
Pathogenic Microbes
111
Although they typically require oxygen, some will grow in anaerobic conditions. As they produce a bright blue-green color that diffuses into its substrate,
a blue-green color has, at times, been observed on substrates (e.g., surgical
dressings) where the bacteria grew.
Pseudomonas aeruginosa frequently occurs as a secondary invader of infected
tissues or tissues which have been traumatized by operation. Children and
immune-suppressed patients are particularly susceptible to infection. Often­
times,infectionsareassociatedwiththeurinaryandrespiratorytracts.Abscesses
may develop in different parts of the body, especially the middle ear. Although
rare, it may also cause endocarditis, pneumonia, meningitis, and systemic
pyocyanic infection. The latter generally occurs in patients with severe burn
wounds where the bacterium enters and spreads throughout the body, causing
endotoxic shock and focal necrosis of the skin and internal organs. As they do
not respond well to antibiotics, systemic infections are almost always fatal. For
this reason, the primary area of concern for this bacterium is in hospitals.
It should be noted that bacteriostatic detergents (e.g., cationic detergents)
provide a growth environment for certain Gram-negative bacteria; (e.g.,
Pseudomonas aeruginosa). Many of these soaps are used in skin antiseptics,
mouthwashes, contact lens solutions, and disinfectants for hospitals.
Pseudomonas aeruginosa is also an insect pathogen and has consequently been
considered for use as an insecticide. Its limited shelf life and potential to cause
disease in humans has been a deterrent from its use as a pest control agent.
Pseudomonas pseudomallei infections may be asymptomatic or result in
acute, toxic pneumonia or overwhelming septicemia. The organism has
been isolated from moist soil, market fruits, and vegetables, and well and
surface waters in Southeast Asia. Pseudomonas maltophilia is suspect as well.
However, over the past few years, the latter suspect has undergone numerous name changes and is now referred to as Stenotrophomonas maltophilia. It is
no longer classified as genus Pseudomonas.
The Pseudomonas bacteria are Gram-negative rods, measuring 1.5 to 3
microns in length by 0.5 microns wide. They grow well on all common nutrient media and grow most rapidly between the temperatures of 30°C and
37°C in aerobic conditions. Once airborne, the bacterium loses its viability
with drying. So exposures must occur shortly after the bacteria have become
dispersed into the air.
Sampling and Analytical Methodologies
If pathogenic bacteria are suspect, the sampling equipment of choice for
low to moderate levels (e.g., less than 10,000/m3) are the culture plate impactors (e.g., Andersen impactor). In situations involving potentially higher
numbers, liquid impingers are preferred, primarily due to their ability to
dilute the solution and plate from several diluents. Notwithstanding surface samples, filter air sampling is easier but may theoretically be used only
112
Indoor Air Quality: The Latest Sampling and Analytical Methods
for the spore-forming Bacillus anthracus for which analysis is not available
commercially. Mycobacterium tuberculosis is also of questionable feasibility.
Although air sampling for Mycobacterium tuberculosis has been attempted
by some environmental professionals, it is not recommended by most
microbial laboratories. Where the concern involves this pathogen, alternative surface sampling may provide more reliable results. Otherwise, a negative air sample can’t be considered conclusive as to the nonpresence of the
pathogen.
In the laboratory, samples that are not already on a culture medium are
plated. Filter surfaces are washed, the suspended material plated on nutrient
media. Impinger solutions are also plated.
Most pathogenic bacteria will grow on tryptic soy agar or a nutrient blood
agar, the same nutrients used to sample for total bacteria during indoor air
quality studies. Although the nutrient media of choice is blood agar, the
microbial laboratory chosen to perform the analysis should be consulted for
their preferred media.
Incubation should take place at 35°C for most pathogenic bacteria.
Pathogenic bacteria tend to grow best at elevated temperatures, and the
higher temperatures restrict growth of most environmental bacteria that
could overrun a sample.
With a few exceptions, colonies may be counted within one to two days.
One such exception is Mycobacterium tuberculosis that require up to two weeks
for colonies to become visible.
Where shipping is necessary, a count may take place upon receipt of a
well-insulated shipment of culture plates. Impinger samples should be
plated prior to shipping to avoid growth within the collection solution during transportation.
Interpretation of Results
Experience and careful consideration of comparative or diagnostic samples
are important for developing sound conclusions. The sampling methodologies alone may damage some of the otherwise viable, unprotected bacteria.
Thus the mere identification of specific microbes in an indoor environment,
particularly in hospitals, may be cause for remediation.
The outdoor environmental contribution of a pathogenic bacterium may
also be important in evaluating the findings and devising a remediation
plan. Where the levels are as high or higher outdoors, indoor exposure controls may be more difficult or, in some cases, not required.
Where air sampling is performed for Mycobacterium tuberculosis, positive
findings of any level should be acted upon. However, negative results may
not have any meaning. Negative findings should not be relied upon where
false negatives, particularly involving drug-resistant strains, can lead to a
lethal, false sense of security.
Pathogenic Microbes
113
Pathogenic Protozoa 37, 38
Typically larger than the bacteria and mold spores, protozoa are unicellular
microorganisms that are free-living and thrive in water. They may be located
in damp soil, mud, drainage ditches, puddles, ponds, rivers, and oceans.
Those that represent an occupational and environmental concern are the
amoebae, measuring in size from 8 to 20 microns in diameter.
Amoeba move by flowing pseudopodia, or false feet, and usually live in fresh
water. They are naked, or unprotected, during vegetation. Otherwise, they
secrete a protective shell. They may be found in home humidifiers where they
have been known to cause an allergic reaction called humidifier fever. The genera Naegleria and Acanthanoeba have been implicated in building-related illness,
yet most amoeba-related disease is associated with waste treatment plants.
In the absence of water, the Naegleria can encyst to protect itself. These spherical cysts are 9 to 12 millimeters in diameter. The seriously parasitic amoebae,
which are not typically found in fresh water, are not generally a concern.
Sampling and Analytical Methodology
Sampling equipment may be the Litton sampler, two in-series all-glass
impingers, or sieve plate impactors. High volume air samples should be collected close to the probable aerosolization source, avoiding other potential
contaminant sources (e.g., not immediately under running water). Equipment
should also be sterilized.
The Litton sampling tube should be cleaned, using 70 percent ethanol and
submerged in two separate distilled water rinses for 30 to 60 minutes each.
The last rinse should be collected and analyzed for background amoeba contamination of the tubing.
The all-glass impingers should be cleaned, and the final rinse water
should be analyzed for background contamination. The final in-series samples (consisting of 150 milliliters of water) should be combined and analyzed collectively.
At the laboratory, each sample solution should be plated in five different
amounts onto nutrient agar plates with the common bacteria Escherichia coli
and incubated between 43°C and 45°C. Pathogenic amoebae will grow more
rapidly than nonpathogenic types in these conditions.
The amounts of solution per sample to be plated should be 0.01, 0.1, 1, 10,
and 100 milliliters. They are treated differently. The 10-milliliter sample
should be centrifuged at 500× gravity for 15 minutes, and the product plated.
The 100-milliliter sample should be filtered through a 1.2 micron pore sized
cellulose filter that must be quartered or halved and inverted in an agar plate.
The smaller aliquots should be plated directly onto separate plates. Assure
all plates have been properly labeled.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Incubation may take up to seven days at 45°C (or at 35°C for some of the
less heat tolerant species), and then a series of more complex manipulation
techniques are performed. The resultant suspension requires an additional
three hours of time-lapsed examinations for concentration determination of
thermophilic Naegleria species. Speciation requires an additional two weeks
in vivo mouse pathogen studies.
Interpretation of Results
Disease, coupled with reservoir source identification, is diagnostic and does
not require quantitation. The existence of these heat-loving amoebae in a
reservoir requires immediate remediation with an oxidizing biocide (e.g.,
sodium hypochlorite or hydrogen peroxide).
Viruses 39
Viruses, the smallest living organisms, are obligate intracellular parasites.
They are subdivided into animal, plant, and bacterial parasites. The size of
animal viruses ranges from 20 to 300 nanometers.
Viruses are host specific and become invasive only when specific host
organs become accessible. Host entry may be through any of a number of
mechanisms, yet most enter through the respiratory tract.
A line of defense (e.g., nasal hairs and mucous secretions) must be passed.
Then, the virus must be transported (e.g., through the blood supply) to its
target cell preference(s). Once the target cells have been identified, the virus
penetrates the cell wall barrier and takes command of the cell’s replicating mechanism. The virus is reproduced within 6 to 48 hours. A protective structure is built around each replicated virus, and the progeny viron
either destroys the host cell or forms a bud that allows it to pursue other
host cells.
Animal viruses are usually recognized by the diseases they cause (e.g.,
AIDS). The greatest concerns with aerosolized animal viruses are influenza, measles, chicken pox, and some colds. Virulence is influenced by the
following:
•
•
•
•
Specific type of virus
Concentration in an aerosol
Aerosol particle size
Individual susceptibility
Indoor contamination occurs in residences, offices, laboratories, hospitals,
and animal confinement areas. Outdoor exposures occur around livestock,
Pathogenic Microbes
115
sewage treatment plants, caves, and water sources. Environmental factors
affecting virus survivability are relative humidity, temperature, wind, ultraviolet radiation, season, and atmospheric pollutants.
Amplification of viruses does not occur without a host. Hence, increased
numbers will not occur in water or organic substrates of air handlers. The air
handlers will merely serve as a means of conveyance. Acids, extreme temperatures (e.g., less than −20°F or greater than 150°F), and drying can, however, damage or destroy most viruses. This information is important for an
exposure-limiting consideration for prevention and control of viruses and
for handling samples.
Sampling is typically neither recommended nor requested. Because viruses
are obligate parasites, they cannot be cultured from environmental samples
on laboratory media. The presence of disease is generally tracked epidemiologically to the source or sources.
Summary
Pathogenic microbes are rarely encountered in indoor air quality situations,
and it is usually the result of an epidemic of cases when they become suspect.
Some attempts are made in hospitals at proactive projections and occasional
sampling. Yet the investigator will generally be called in for assistance after
an elevated number of suspect disease cases are associated with a building.
The challenge may be more that of confirmation of a suspect agent and locating the source.
References
1. Bailey, M.R., and E.G. Scott. Diagnostic Microbiology, 3rd ed. C.V. Mosby
Company, St. Louis, Missouri (1970).
2. Conant, N.F., et al. Manual of Clinical Mycology, 3rd ed. W.B. Saunders Company,
Philadelphia (1958).
3. U.S. Department of Health, Education, and Welfare. Occupational Diseases: A
Guide to Their Recognition. U.S. Government Printing Office, Washington, DC,
revised edition (June 1977).
4. Rhame, F.S. Endemic Nosocomial Filamentous Fungal Disease: A Proposed
Structure for Conceptualizing and Studying the Environmental Hazard. Infection
Control. 7(2):126 (1986).
5. Krasinski, K., et al. Nosocomial Fungal Infection during Hospital Renovation.
Infection Control. 6(7):278–82 (1985).
116
Indoor Air Quality: The Latest Sampling and Analytical Methods
6. Weems, J.J., et al. Construction Activity: An Independent Risk Factor for Invasive
Aspergillosis and Zygomycosis in Patients with Hematologic Malignancy.
Infection Control. 8(2):71–5 (1987).
7. Cross, A.S. Nosocomial Aspergillosis: An Increasing Problem. Journal of
Nosocomial Infection. 4(2):6–9 (1985).
8. Mascola, J.R., and L.S. Rickman. Infectious Causes of Carpal Tunnel Syndrome:
Case Report and Review. Reviews of Infectious Diseases. 13(5):911–7 (1991).
9. Kilburn, C.D., and D.S. McKinsey. Recurrent Massive Pleural Effusion due
to Pleural, Pericardial, and Epicardial Fibrosis in Histoplasmosis. Chest.
100(6):1715–7 (1991).
10. Centers for Disease Control. Update on Coccidioidomycosis in California.
Morbidity and Mortality Weekly Report. 43(23):421–3 (1994).
11. Chen, G.H., et al. Case Records of the Massachusetts General Hospital—Weekly
Clinicopathological Exerciser. New England Journal of Medicine. 330(7):490–6 (1994).
12. Paya, C.V. Fungal Infections in Solid-Organ Transplantation. Clinical Infectious
Diseases. 16(5):677–88 (1993).
13. Pfeiffer, T.J., and D.H. Ellis. Environmental Isolation of Cryptococcus Neofor­
mans Var. Gattii from Eucalyptus Tereticornis. Journal of Medical and Veterinary
Mycology. 30(5):407–8 (1992).
14. Gallup, J., and M. Velesco. Characteristics of Some Commonly Encountered Fungal
Genera. Environmental Microbiology Laboratory Inc., Daly City, California
(1999).
15. Ajello, L., et al. Microbes in the Indoor Environment: A Manual for the Indoor Air
Quality Field Investigator. Path Con Laboratories, Norcross, Georgia (1998).
16. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida, p. 259 (1995).
17. Morris, G.K., and B.G. Shelton. A Suggested Air Sampling Strategy for Microorganisms
in Office Settings (Technical bulletin). PathCon Laboratories, Norcross, Georgia
(1994).
18. ACGIH Committee on Bioaerosols. Guidelines for the Assessment of Bioaerosols in
the Indoor Air Environment—Fungi. ACGIH, Cincinnati, Ohio (1989).
19. Stewart, F.S. Bacteriology and Immunology for Students of Medicine, 9th ed. Williams
and Wilkins Company, Baltimore, Maryland (1968).
20. Morris, G.K., and B.G. Shelton. Legionella in Environmental Samples: Hazard
Analysis and Suggested Remedial Actions (Technical Bulletin 1.4). PathCon
Laboratories, Norcross, Georgia (1995).
21. Brock, T.D., and M.T. Madigan. Biology of Microorganisms, 6th ed. Prentice Hall,
Englewood Cliffs, New Jersey (1991), pp. 518–520.
22. Burge, H.A. Bioaerosols—Legionella Ecology. Lewis Publishers, Boca Raton,
Florida (1995), pp. 49–76.
23. Morris, G., et.al., Legionella Bacteria in Environmental Samples: Hazard Analysis
and Suggested Remedial Actions (Technical Bulletin 1.5), PathCon Laboratories,
Norcross, Georgia (1998).
24. New York Times. Legionella from misting in grocery store. 139:A1(N)
(Jan. 11, 1990).
25. Hlady, W.G., et al. Outbreak of Legionnaire’s Disease Linked to a Decorative
Fountain by Molecular Epidemiology. American Journal of Epidemiology.
138(8):555–62 (1993).
26. Alcamo, I.E. Fundamentals of Microbiology, 3rd ed. Benjamin/Cummings
Publishing Company, Inc., Redwood City, California. (2004), p. 243.
Pathogenic Microbes
117
27. Gorman, G.W., J.M. Barbaree, J.C. Feeley, et al. Procedures for the Recovery of
Legionella from the Environment (Bulletin). CDC, Atlanta, Georgia (November
1992).
28. Sheldon, B.G. Social Security Building Incident Where Settlement is Alledged
to Have Been Quite Expensive (Oral communication). PathCon Laboratory,
Norcross, Georgia (July 1995).
29. Atlas, R.M., and R. Bartha. Microbial Ecology: Fundamentals and Applications.
Benjamin/Cummings Publishing Company, Menlo Park, California (1987),
p. 476.
30. Burrows, W. Textbook of Microbiology. W.B. Saunders Company, Philadelphia
(1968), pp. 614–619.
31. Morris, G.K. Exposures to Bacillus Anthracis (Oral communication). PathCon
Laboratories, Norcross, Georgia (November 1995).
32. Brock, T.D., and M.T. Madigan. Biology of Microorganisms, 6th ed. Prentice Hall,
Englewood Cliffs, New Jersey (1991), pp. 513–514.
33. ACGIH Committee on Bioaerosols. Guidelines for the Assessment of Bioaerosols in
the Indoor Air Environment—Bacteria. ACGIH, Cincinnati, Ohio (1989).
34. Stewart, F.S. Bacteriology and Immunology for Students of Medicine, 9th ed. Williams
and Wilkins Company, Baltimore, Maryland (1968), pp. 357–60.
35. Ibid., pp. 278–280
36. Ibid., pp. 282–283.
37. ACGIH Committee on Bioaerosols. Guidelines for the Assessment of Bioaerosols in
the Indoor Air Environment—Protozoa. ACGIH, Cincinnati, Ohio (1989).
38. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995),
pp. 122–123.
39. ACGIH Committee on Bioaerosols. Guidelines for the Assessment of Bioaerosols in
the Indoor Air Environment—Viruses. ACGIH, Cincinnati, Ohio (1989).
7
Toxigenic Microbes
Toxigenic microbes are those that produce mycotoxins and endotoxins, the
toxins associated with fungi and bacteria, respectively. As toxigenic microbes
have often been overlooked, environmental professionals are becoming more
aware of their potential impact on the indoor air quality.
Organic dust toxic syndrome is thought to be associated with a complex
mix of mycotoxins, endotoxins, antigens (allergenic material), and glucans.
This is a poorly characterized condition similar to “humidifier fever.” Flu-like
symptoms include fever, chills, muscle aches, malaise, and chest tightness,
and illness is short lived, usually less than 24 hours. Exposures and symptoms are generally associated with high dust levels in composting and some
agricultural operations.
Not only do mycotoxin and endotoxin exposures result in adverse health
effects, but they may have a positive impact as well. Whereas one mold may
cause cancer, another may protect against pathogens. Excessive exposures
to endotoxins may result in respiratory distress, shock, and death, but lowlevel exposures may stimulate the immune system, which may help reduce
the risk of cancer.
Each of the above-mentioned toxigenic microbes is worthy of mention and
should not be overlooked when assessing an indoor air environment. They
are discussed herein.
Mycotoxins1,2
Mycotoxins are toxic by-products of the metabolic process of fungi. Those
that produce the mycotoxins gain a competitive edge over other microorganisms for food. Many fungi produce at lease one mycotoxin. Some
produce many different mycotoxins, and others do not produce any. See
Table 7.1.
Exposures to mycotoxins may occur by eating poisonous/hallucinogenic
mushrooms, eating contaminated foods, breathing heavily contaminated air,
or handling contaminated materials with unprotected hands. The greatest
impact has been on agriculture and livestock. The feeds become contaminated with toxin-producing fungi. The livestock eat the heavily contaminated feeds with a possible outcome of death.
119
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Indoor Air Quality: The Latest Sampling and Analytical Methods
TABLE 7.1
Mycotoxins Associated with Certain Fungi3
Fungus
Acremonium spp.
Alternaria alternate and Phoma sorghina
Aspergillus clavatus
Aspergillus flavus and
Aspergillus parasiticus
Aspergillus fumigatus
Aspergillus nidulans, Aspergillus versicolor,
and Cochliobolus sativus
Aspergillus ochraceus, Penicillium verrucosum,
and Penicillium viridicatum
Cladosporium spp.
Cladosporium cladosporioides
Claviceps purpurea
Fusarium graminearum
Fusarium moniliform
Fusarium pose and Fusarium sporotrichoides
Penicillium chrysogenum
Penicillium crustosum
Penicillium expansum
Penicillium griseofulvum and Penicillium viridicatum
Pithomyces chartarum
Stachybotrys chartarum (atra)
Tolypocladium inflatum
Mycotoxin
Cephalosporin (antibiotic)
Tenuazoic acid
Cytochalasin E
Patulin
Aflatoxins
Fumitremorgens
Gliotoxin
Sterigmatocystin
Ochratoxin A
Epicladosporic acid
Cladosporin and emodin
Ergot alkaloids
Deoxynivalenol
Zearalenone
Fumonisins
T-2 toxin
Penicillin (antibiotic)
Penitrem A
Roquefortine C
Citrinin,
Patulin,
Roquefortine C
Griseofulvin
Sporidesmin
Phylloerythrin
Satratoxins,
Verrucarins,
Roridins,
Stachybocins
Cyclosporin (antibiotic)
The mycotoxins are primarily concentrated in the cell walls of the fungal
spores, but these by-products have also been identified in the fungal mycelium
and food substrates. For instance, Aspergillus flavus produces an aflatoxin in the
spore wall. This aflatoxin rapidly may diffuse out of the wall and into a water
reservoir. However, mycotoxins are not known to become airborne without a
carrier (e.g., mold spores and mycelium) and are not volatile compounds.
Possible short-term symptoms of excessive exposures to mycotoxins include
nausea, vomiting, dermatitis, cold and flu symptoms, sore throat, fatigue,
Toxigenic Microbes
121
and diarrhea. Some other reported effects that are more species dependent are eczema, photosensitization, hemolysis, hemorrhage, and impaired
or altered immune function that can result in opportunistic infections.
Long-term effects are even more species dependent. Specific species may
be hepatotoxic (e.g., Aspergillus flavus), cytotoxic (e.g., Aspergillus fumigatus),
teratogenic (e.g., Penicillium viridicatum), tremorgenic (e.g., Penicillium expan­
sum), tumorigenic (e.g., Aspergillus fumigatus), nephrotoxic (e.g., Aspergillus
clavatus), mutagenic (Aspergillus parasiticus), or carcinogenic (e.g., Aspergillus
flavus, Cochiobolus sativus).4
Some mycotoxins are beneficial to man in the form of antibiotics (e.g.,
Penicillium chrysogenum). Antibiotics are toxic to pathogenic bacteria. As such,
the antibiotic mycotoxins revolutionized the world and saved many lives.
There is a dose-response relationship for mycotoxins similar to that of chemical toxins. The impact of mycotoxins is based upon the type of toxin, the animal species impacted, the route of entry, and susceptibility of the individual.5
Disease and Occurrence
Throughout history, mycotoxins have played a significant role in the health of
man and animal. Toxicity and dramatic exposures have typically been associated with ingestion of contaminated foods. Ergotism, also known as Saint
Anthony’s Fire, was documented as early as 430 B.C. by the Spartans. It was
caused by ingestion of rye that was contaminated with alkaloid-containing
fungi. Symptoms were gangrene, convulsions, and death.
In 1960, feed (i.e., Brazilian peanut meal) that was contaminated with
Aspergillus flavus killed 100,000 turkeys in the United Kingdom. The toxins
that were identified came to be named “aflatoxins.”
Aspergillus flavus and Aspergillus parasiticus create aflatoxins that are carcinogenic and may cause some short-term health effects that have yet to be
clarified by medical researchers. These molds grow predominately in warm,
humid environments and are typically associated with peanuts, grains, sweet
potatoes, corn, peas, and rice. Aflatoxins have been reported to cause liver
carcinomas in animals and are believed to be among the most potent of carcinogens in man.6 They are primarily associated with liver cancer, and there
have been some concerns raised regarding inhalation and lung cancer.
There is one report of two deaths due to pulmonary adenomatosis that are
thought to be related to airborne aflatoxin exposures. Although autopsies
indicated the presence of aflatoxin in both patients’ lungs, the findings were
not conclusive.7 The verdict regarding airborne aflatoxins is still out.
Trichothecene toxins are cytotoxins produced by some species of Fusarium,
Acremonium, Trichoderma, Myrothecium, and Stachybotrys. Reported symptoms
include headaches, sore throats, hair loss, flu-like illness, diarrhea, fatigue,
dermatitis, and generalized malaise.
The year 2000 saw the birth of a new cottage industry—the quest for and
remediation of “toxigenic molds.” Based on a multimillion-dollar law suit,
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Stachybotrys chartarum was tagged by the news media as the “death mold.”
Investigators began targeting Stachybotrys chartarum with fervent interest
in an effort to stem the tide of panic. Some “experts” began targeting the
genus Penicillium as well. Indoor environments with water damaged building materials and potentially toxigenic fungi were posted with “biohazard”
signs and remediated at great expense to the building owner or insurance
company. Most, if not all, of the investigations mentioned above involving
expensive remediation have yet to confirm the presence of mycotoxins. So,
as of the publication of this book, the saga continues.
Many species of Penicillium produce mycotoxins. Some species (e.g.,
Penicillium viridicatum) produce mycotoxins that are potentially tumorigenic,
teratogenic, and hepatotoxic.4 Others produce antibiotics, including penicillin (e.g., Penicillium chrysogenum).
To complicate matters, toxins are not always produced. The nutrient (or
substrate) upon which the mold grows impacts its metabolites. Indoor environments and laboratory nutrients may result in a variation from the norm.
Thus the presence of amplified numbers of mycotoxin-producing fungi in a
building does not necessarily follow that it is producing the toxin. Likewise,
the failure of a mold to produce toxins in laboratory conditions does not
necessarily mean that it does not produce the toxin under natural environmental conditions.
Other factors that may affect production of mycotoxins are competition
from other microbes, pH, temperature, and water. For instance, aflatoxin
production is associated with drought and heat stress.
A recent research publication indicated:
In many cases, the presence of fungi thought to produce the mycotoxins
was not correlated with the presence of the expected compounds. However,
when mycotoxins were found, some toxigenic fungi usually were present,
even if the species originally responsible for producing the mycotoxin was
not isolated. We concluded that the identification and enumeration of fungal species present in bulk materials are important to verify the severity
of mold damage but that chemical analyses are necessary if the goal is to
establish the presence of mycotoxins in moldy materials.8
In other words, the presence of a toxin-producing mold does not always a
toxin make. Nevertheless, given the cost and time required for toxin analysis, as well as potential difficulties in detecting low levels of these chemical agents in environmental samples, assessment for mycotoxin-producing
fungi is still regarded as the most practical means of assessing potential
toxin exposures in indoor environments.
In summary, most cases of mycotoxin poisoning occur in rural and agricultural settings as a result of ingestion or skin contact. There have been
minimal studies and research into the possible relationship between airborne mycotoxins and its impact on humans.
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Toxigenic Microbes
Sampling and Analytical Methodologies2
There are two different approaches to sampling for mycotoxins. The fungi
may be identified with an emphasis on fungi identification for those molds
that may potentially create toxic by-products, or the investigator may focus
on toxin identification. The latter, although preferred, is neither easy nor
technically feasible for commercial laboratories.
Fungi Identification
Species identification is a must and can only be determined through viable
air sampling. Yet where the fungi are to be identified from culturing, many
of the toxin-producing fungi may not compete well with the other fungi,
or they may no longer be viable while the toxins still persist in nonviable
spores. Special nutrient media may be necessary depending on the investigators emphasis (e.g., Stachybotrys), and the laboratory and its preferences (e.g.,
special cellulose agar) See Figure 7.1.
Mycotoxins have the same effect—alive or dead—and the effect of toxins is based on a dose-response relationship. For this reason, total viable/
nonviable air sampling is as important as viable air sampling. Both types
of sampling should be performed in tandem. The methods are described in
Chapters 5 and 7.
(a)
FIGURE 7.1
Photomicrographs of Toxigenic Molds: (a) Stachybotrys, (b) Fusarium, and (c) Aspergillus flavus
[Courtesy of Sean Abbott, PhD, Natural Sink Mold Lab, Reno, Nevada].
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Indoor Air Quality: The Latest Sampling and Analytical Methods
(b)
(c)
FIGURE 7.1
(Continued)
Toxin Identification
Sampling methodologies for mycotoxins have recently been developed and
have become available commercially. Methods include air, contaminatedsurface wipes, surface dust, and bulk sampling.
Air sampling requires a sufficient amount of air volume to enable capture of greater than 100,000 spores per sample. Based on an airborne mold
Toxigenic Microbes
125
spore exposure of 100 counts/m3, the latter 100,000 spores sample would
require an air volume of not less than 106 liters, or 46 days of continuous
sample at 15 liters per minute. If the airborne mold spore exposure were
1000 counts/m3 (an unlikely indoor airborne mold spore count), the sample
duration required would be about 5 days. Prior to taking mycotoxin air samples, airborne mold spore levels should be determined using one of viable/
nonviable sampling methodologies in Chapter 5. With known airborne spore
counts, the investigator can calculate minimum air volume required to collect 100,000 spores. Report sample number (or location) and air volume to the
laboratory.
Contaminated-surface wipe sampling may only be performed on areas
where molds have been identified and surfaces are heavily contaminated.
A dusty surface is not sufficient and requires a different sample technique.
Sample supplies should include sterile methanol wipes or swabs. Some laboratories supply field kits that consist of enclosed cotton swabs with methanol
as well as templates to delineate the area(s) sampled. Lightly contaminated
surfaces may require larger surface area sampling than heavily contaminated surfaces, and the size of the area template or number of areas sampled
for one analytical run should be adjusted accordingly. Report sample number (or location) and surface area sampled to the laboratory.
Surface dust samples require the collection of a minimum of one teaspoon of dust. For general dust sampling methods, see the “Surface Dust
Collection” section in Chapter 15. The surface dust sampling methods for
mycotoxins should be performed with supplies that have been cleaned (e.g.,
wash scraping items and collection attachments with soapy water, rinse,
and thoroughly dry). A minimum area of 1 square foot should be sampled.
Report sample number (or location) and surface area sampled to the laboratory. Bulk samples may be taken of carpeting, insulation, gypsum board,
wood flooring, sheet vinyl wallpaper, and other materials that have visible
evidence of mold growing on the surface(s). The size of the material selected
to sample should be a least 1 inch square for heavy contamination and as
much as 1 square foot for light contamination. Using clean tools, cut the
material out, place it in a ziplock baggie, and label the bag with the sample
number or location.
All samples should be labeled at the time each sample is taken, and the
investigator must report to the laboratory sample number (or location) and
air volume or surface area sampled. A log of sample number(s) should be
maintained by the investigator with a detailed description of the sample
sites (e.g., exact location where the sample was taken, type of material, and
appearance of the sample), environmental conditions, and other information
that may be applicable regarding the sample. All samples with required laboratory data and chain of custody should be shipped in a chilled container
(e.g., Styrofoam cooler with a cool pack).
Analysis involves dust extraction and high-pressure liquid chromato­
graphy or thin-layer chromatography. See Table 7.2 for a sample of laboratory
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Indoor Air Quality: The Latest Sampling and Analytical Methods
TABLE 7.2
Quantified Mycotoxins Produced by Cultivated Fungal Species10
Mold
Aspergillus fumigatus
Aspergillus niger
Aspergillus parasiticus
Penicillium oxalicum
Aspergillus parasiticus
Toxin
Spores (ng/g)
Fumigaclavin C
Aurasperone
Aflatoxin B1
Secalonic acid D
Norsolorinic acid
930,000
460,000
16,600
1,890
280
quantification results of mycotoxins produced by some cultivated fungal
species.
In response to food testing required by the U.S. Food and Drug
Administration (FDA), owners of granaries and corn storage facilities routinely perform a quick test for the presence of aflatoxin. Although the FDA
probes larger samples and has analyses performed by a commercial laboratory, colorimetric test kits (based on immunoassay tagging of the mycotoxin)
are available commercially and are readily used for screening by the storage
facilities.9 This approach has yet to be introduced into or used by environmental professionals to screen air and surface samples.
Another technique that may hold some promise for environmental professionals is the ELISA detection kits. They are currently used to screen for
mycotoxins in grains, nuts, and spices. The kits are commercially available
and can be performed by the investigator within two hours. They are qualitative and quantitative in separate kits for the following:
•
•
•
•
•
•
Aflatoxin
Fumonisin
Ochratoxin
T-2 Toxin
Vomitoxin
Zearalenone
Interpretation of Results
There are no definitive guidelines for interpretation of results. First, the fungi
able to produce toxins may not produce these mycotoxins under the conditions that the contaminant is being assessed. Second, if the toxins could be
identified, there are no known comparative values by which to determine
that a problem does indeed exist.
On the other hand, a thorough assessment of dust for the presence of mycotoxins in a given environment may permit an investigator to determine if
the suspect mycotoxins are present or not. The type of toxin sought should
Toxigenic Microbes
127
be based on fungal species found. Finding that the suspect mycotoxins are
present could be important information in itself, or outdoor samples may be
compared to indoor samples.
Also, telltale symptoms may be used in conjunction with the presence of
fungi known to potentially cause the same symptoms. Although this technique has been used more than the mycotoxin identification method, the
symptoms must be properly diagnosed and some symptoms may be caused
by other environmental exposures. In the latter case, a source misdiagnosis could result in misdirected efforts to remediate. If fungi (e.g., Penicillium)
is remediated and the problem is associated with a toxic chemical (e.g.,
Chlordane), the true cause of the symptoms remain unidentified.
The environmental professional is on his or her own or must rely on guidance from one with experience in this area of expertise. The laboratory chosen to perform the work should be able to either provide guidance or direct
you to someone competent in that area. Each case is unique and depends on
several variables including intent and sampling strategy. All factors must be
considered in the final interpretation.
Bacterial Endotoxins11–13
Endotoxins are toxic components of the lipopolysaccharide, cellular membrane of Gram-negative bacteria. Although the bacteria may be rendered
nonviable, the endotoxin retains its toxicity, even through extremely high
temperatures (up to 110°C) that may not normally be exceeded in an autoclave.11 Their impact on the individual is dose-related, and airborne levels
have been reported from a variety of work environments.
The most commonly reported cases have involved processing of vegetable
fibers, fecal material in agriculture, and human waste treatment plants. Most
worker exposures occur in cotton gins/mills, swine confinement buildings,
poultry houses, grain storage facilities, sewage treatment facilities, and wood
chip processing/saw mills. Other areas include the aerosolizing of machining fluids in metal processing,14 and aerosolized contaminated water supplies in hospitals15 and “humidified” office buildings.16 See Table 7.3 for a
recap and amplification on the environmental settings in which endotoxins
have been identified at levels significant enough to cause illness.
Symptoms typically involve elevated temperatures. In the cotton industry, this is referred to as “mill fever.” Onset of fever is followed by malaise,
respiratory distress (e.g., coughing, shortness of breath, and acute air flow
obstruction), diarrhea, vomiting, hemorrhagic shock, tissue necrosis, and
death. However, the latter, more serious symptoms are rare.
Some researchers have also been able to demonstrate acute changes in
the respiratory FEV1 i.e., (forced expiratory volume in 1 second) and suggest
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Indoor Air Quality: The Latest Sampling and Analytical Methods
TABLE 7.3
Occupational Environments Where Endotoxins Have Been Identified and
Known to Pose a Problem16
Cotton gins/mills
Swine confinements
Grain storage, handling, and processing facilities
Poultry barns
Sewage treatment and processing facilities
Wood chipping operations
Saw mills
Flax mills
Machine shops
Fiberglass manufacturing19
repeated exposures may cause a syndrome similar to chronic bronchitis.18
Other investigators feel that endotoxins add to the virulence of a parasite,
enhancing the perils of disease. Once again, hospitals provide a special niche
for such occurrences. Paradoxically, on the same note, it is also thought that
the endotoxins that threaten one’s health can enhance the body’s immune system by challenging pathogenic bacteria, viral infections, and cancer.19 While
increasing the risk of hypersensitivity disease, endotoxins are a powerful,
nonspecific stimulant to the immune system.20
Sampling and Analytical Methodology
Bulk sampling of humidifier reservoirs and other potential endotoxin sources
is considered the most reliable means of sampling for endotoxins. All samples
should be collected in sterilized glassware and analyzed promptly, before
microbial and subsequent endotoxin amplification can occur. Sterilization of
all glassware and associated laboratory equipment should be baked at 210°C
for one hour to destroy most pre-existing endotoxin contaminants. Plastic
items should also have been sterilized (e.g., ethylene oxide) or sonication in
endotoxin-free 1 percent triethylamine. As they may adsorb large amounts
of lipopolysaccharides, sampling supplies made of polypropylene plastics
should be avoided. Polystyrene is preferred!
Air sampling has been performed with limited success. Attempts have
been made by dust/particle collection techniques. The methods of collection have included total dust samplers, cascade impactors (size separators),
vertical elutriators (used for respirable dust sampling in the cotton industry),
cyclones (used for personal respirable dust sampling), and midget impingers
(personal samples that collect particles greater than 1 micron in size). As
endotoxins act primarily in the lower region of the lungs (which mostly
involves particles of less than 5 microns), “respirable dust samplers” are preferred. For those considering the possibility of viable sampling for bacteria
129
Toxigenic Microbes
to get a gauge as to endotoxin levels, endotoxin and viable bacteria samples
have not been found to correlate.21
Sample collection flow rates have varied, based upon the type of sampler.
They have been as low as 2 or 4.5 liters per minute for total dust to as high as
7.4 liters per minute with the vertical elutriator. Although not specified, one
study suggests that in order to detect down to 14 picograms per cubic meter,
a minimum of 7.5 cubic meters of air should be sampled.22 Another study
sampled at 2 liters per minute for the duration of a workshift, for a volume of
960 liters.23 It is quite apparent that laboratories vary in their analytical methods and, therefore, their detection capabilities. For this reason, the laboratory
should be consulted prior to sampling.
Filter media are also worthy of mention. In one study, recovery of endotoxin
from four different types of filters was compared to a “no filter” control. The
recovery rates, as reflected in Table 7.4, were extremely poor (e.g., polyvinyl
chloride membrane filter) to moderate (e.g., mixed cellulose ester membrane
filter).21 In a later publication, the same investigator who performed the filter
media testing proposed the use of “0.4-µm polycarbonate filters” in a standard protocol for sampling endotoxins.24
Upon selection of sampling media, all supplies should be precleaned and
sterilized, including the filters and cassettes. Cassettes can be cleaned by
sonication in endotoxin-free 1 percent triethylamine, and all other supplies
that might come in contact with the sample (including the laboratory implements) should be heated at 210°C for 1 hour.23 As ability to perform these processes is generally not within the realm of the environmental professional,
supplies (including filters) are best provided by the laboratory.
After collection, the samples and a field blank (unsampled filter) should be
sealed in airtight plastic enclosures, placed in a cold storage container, and
TABLE 7.4
Recovery Efficiencies of Endotoxin
Filter Type
Polyvinyl chloride (5.0-µm
pore membrane)
Polyflon (woven Teflon)
Teflon membrane (1.0-µm
pore membrane)
Cellulose mixed ester
(0.45-µm pore membrane)
Lipopolysaccharide (LPS)
control (no filter)
Recovery (ng of NP-1
Activity/ ng LPS Added)
Percent Recovered as
Compared to the
Controls (%)
0.064
10.8
0.206
0.229
34.4
38.2
0.252
42.1
0.599
–
Note: NP-1 = Reference endotoxin.
Source: Milton, D., et al. American Industrial Hygiene Association Journal. 51(6):333,
(1990). With permission.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
sent immediately to the laboratory. Do not freeze the samples.22 Each of the
samples should be analyzed at the same time, by the same method, within
the same laboratory.
In the 1940s, endotoxin was measured by injecting rabbits and monitoring
increased body temperatures. The sensitivity was 100 picograms, but rabbits
and preparations were inconsistent.23 Referred to as the Pyrogen Test, this
method remained in place until the discovery of the unique effects endotoxin had on the blood cells of the horseshoe crab.
In 1977, the FDA licensed the more sensitive Limulus Amebocyte Lysate
(LAL) Assay as an alternative to the Pyrogen Test. An extract is made from
amebocytes of the Limulus polyphemus (or horseshoe crab). In the presence of
endotoxins, clotting occurs. There is a relationship between the amount of
endotoxin present and the rate/amount of clotting.
Samples are extracted and tested according to one of four principal methodologies that are based upon blood cell clotting. Extraction methods vary
as much as the analytical methods. In a proposed standard method, however, the recommended procedure is to “extract samples in 0.05 M potassium
phosphate, 0.01 percent triethylamine, pH 7.5, using bath sonication.”
Analytical methods include the gel-clot test, calorimetric test, chromogenic test, and Kinetic-Turbidimetric Limulus Assay with Resistant-parallelline Estimates (KLARE) Test. Due to its precision, sensitivity, resistance to
interferences, internal validation of estimates, and ability to provide quantitative as well as qualitative information, the KLARE test is preferred by
researchers, and there is an attempt to standardize the use of this test as
well.25 However, despite all the studies and research, the choice of method is
going to be laboratory dependent.
Interpretation of Results
Results are reported in terms of equivalent weight per volume (e.g., ng/mL
or ng/m3), equivalent mass (e.g., ng/mg), or potency endotoxin units per
volume (e.g., EU/m3). An endotoxin unit is defined as the potency of 0.10
ng of reference standard endotoxin.24 The U.S. Reference Standard EC-5 for
endotoxin has a conversion factor of 10 EU per nanagram (ng) of substance.
With the results in hand, interpretation is precarious at best. There have
been no standardized means for interpreting endotoxin results. Furthermore,
variations among laboratories have been as much as 1000-fold. However,
results are less than a tenfold difference where a laboratory uses the LAL
from the same lot.26 It thus becomes evident that a single exposure limit is
not feasible, but relative limit values for samples analyzed at the same time,
under similar methodologies and LAL lot, are indicated. Many of the more
prominent researchers and commercial laboratories tend toward comparative sampling—complaint area(s) verses noncomplaint area(s). When sampling for endotoxins in a metal fabrication shop around the cutting fluids, a
comparative sample may be collected in an office. When sampling in a turkey
Toxigenic Microbes
131
processing plant, a comparative sample may be collected in the administrative area. Relative differences should shift simultaneously along with variances created by the different approaches.
According to the American Conference of Governmental Industrial
Hygienists (ACGIH) Committee on Bioaerosols, endotoxin levels between 10
and 100 times the background levels (e.g., noncompliant areas), coupled with
health effects consistent with elevated exposures, should be remediated. Thus
10 times the background levels is the ACGIH proposed relative limit value.26
A safety factor should be considered. The ACGIH suggests 30 times the
background levels, in the absence of symptoms.26
Summary
Mycotoxins are toxins concentrated in the cell walls of mold spores—alive
or dead. They are a highly controversial topic brought on by the media,
and they are here to stay. They are often implicated by mold types (e.g.,
Stachyborys chartarum), but they are not always produced. So, the assumption that the toxigenic mold is producing mycotoxins is all too often made.
There are now methods available to confirm or deny the presence of many
of the mycotoxins.
Endotoxins are toxins produced by Gram-negative bacteria. Although they
produce some of the symptoms occasionally encountered in indoor air quality
investigations, they are frequently overlooked as a potential problem source.
Both mold and bacterial toxins are infrequently assessed, and it is difficult
to trace down a laboratory with the capability to do the analyses. Keep in
mind that more than 50 percent of the investigations in one study group
remain unsolved. The investigator should be aware and consider the possibility of microbial toxins when assessing indoor air quality.
References
1. Pleil, J.D. Demonstration of a Valveless Injection System for Whole Air Analysis of
Polar VOCs. Proceedings of the 1991 International Symposium on Measurement
of Toxic and Related Air Pollutants. Air and Waste Management Association,
Pittsburgh, Pennsylvania (1991).
2. ACGIH Committee on Bioaerosols. Guidelines for the Assessment of Bioaerosols in
the Indoor Air Environment Mycotoxins. ACGIH, Cincinnati, Ohio (1989).
3. Sheldon, B.G. Social Security Building Incident Where Settlement Is Alleged to Have
Been Quite Expensive (Oral communication). PathCon Laboratory, Norcross,
Georgia (July 1995).
132
Indoor Air Quality: The Latest Sampling and Analytical Methods
4. ACGIH. Bioaerosols: Assessment and Control. ACGIH, Cincinnati, Ohio (1999),
p. 24–3.
5. Cox, C.S., and C. Wathes. Bioaerosols Handbook. CRC/LewisPublishers, Boca
Raton, Florida (1995), p. 375.
6. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), p. 90.
7. Cox, C.S., and C. Wathes. Bioaerosols Handbook. CRC/Lewis Publishers, Boca
Raton, Florida (1995), pp. 375–6.
8. Tuomi, T., et al. Applied Environmental Microbiology. 66(2) (2000), pp. 1899–1904.
9. Aflatoxin Nature’s Most Potent Carcinogen (Handout). Neogen Corporation,
Lansing, Michigan (1996).
10. ACGIH. Bioaerosols: Assessment and Control. ACGIH, Cincinnati, Ohio (1999),
p. 24–4.
11. ACGIH Committee on Bioaerosols. Guidelines for the Assessment of Bioaerosols in
the Indoor Air Environment Endotoxins. ACGIH, Cincinnati, Ohio (1989).
12. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), p. 78.
13. ACGIH. Bioaerosols: Assessment and Control. ACGIH, Cincinnati, Ohio (1999).
14. Gordon, T. Acute Respiratory Effects of Endotoxin Contaminated Machining
Fluid Aerosols in Guinea Pigs. Fundamental and Applied Toxicology. 19:117–23
(1992).
15. Burrell, R. Human Responses to Bacterial Endotoxin. Circulatory Shock. 43:137
53 (1994).
16. Jacobs, R.R. Airborne Endotoxins: An Association with Occupational Lung
Disease. Applied Industrial Hygiene. 4(2):50 (1989).
17. ACGIH. Bioaerosols: Assessment and Control. ACGIH, Cincinnati, Ohio (1999),
p. 23–2.
18. Reynolds, S.J., and D. Milton. Comparison of Methods for Analysis of Airborne
Endotoxin. Applied Occupational Environmental Hygiene. 8(9):761–7 (1993).
19. Jacobs, R.R. Airborne Endotoxins: An Association with Occupational Lung
Disease. Applied Industrial Hygiene. 4(2):52 (1989).
20. Rietschel, E.T., and H. Brade Bacterial Endotoxins. Scientific American. 267(2):55–61
(1992).
21. Milton, D., et al. Endotoxin Measurement: Aerosol Sampling and Application
of a New Limulus Method. American Industrial Hygiene Association Journal.
51(6):331–7.
22. Reynolds, S.J., and D. Milton. Comparison of Methods for Analysis of Airborne
Endotoxin. Applied Occupational Environmental Hygiene. 8(9):762 (1993).
23. Milton, D., et al. Endotoxin Measurement: Aerosol Sampling and Application of
a New Limulus Method. American Industrial Hygiene Association Journal. 51(6):333
(1990).
24. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), p. 83.
25. Ibid., p. 82.
26. ACGIH. Bioaerosols: Assessment and Control. ACGIH, Cincinnati, Ohio (1999),
p. 23–10.
Section III
Chemical
Unknowns and Gases
8
Volatile Organic Compounds
In 1995 the National Institute for Occupational Safety and Health (NIOSH)
reported 17 percent of all its indoor air quality surveys had identified volatile
organics as either the cause of or contributor to the indoor air quality complaints. Many office spaces have residual organic components in the air from
construction, renovation, maintenance, janitorial, chemical usage/processing (e.g., spray painting associated with marketing projects), and pest control
activities. There is also off-gassing from new furnishings, building materials,
and office supplies/equipment. Some of the organics may originate from the
growth of microbes. Tobacco smoke, deodorants, and perfumes contribute to
the total organic loading.
Some indoor chemical contaminants originate outdoors. Outdoor con­
taminants enter the indoor air predominantly through the fresh air intake
but may also enter through structural penetrations or porous structural surfaces. There may be an activity or activities involving chemical within the
building whereby the chemicals are exhausted on the roof, entrained in the
air currents, and reenter the building through the fresh air intake. This is not
as frequently encountered as chemicals emitted from other sources in the
vicinity of the building.
Automobile exhausts and industrial pollutants prevail in large cities and
around industrial plants. Even food manufacturing operations have been
known to generate organic chemicals. Environmental organic compounds
also evolve from nature’s store of plant life.
Industrial activities generate organic air pollutants both inside and out­
side. Although most of these chemicals are known, some are by-products
of multiple-chemical processing and chemical treatments. Stack exhausts
may service several areas with different chemical contributions, and complex chemical reactions in the stacks result in complex chemical mixtures in
ambient air.
Incidents of chemical storage fires or petrochemical explosions result in
the release of unknown organic by-products. Fires in transport systems and
buildings result in the release of unknowns. The possibilities are infinite!
As defined by the U.S. Environmental Protection Agency (EPA) volatile
organic compounds vaporize (become a gas) at room temperature. This
includes all organic compounds with up to seventeen carbons in their
molecular structure that have a boiling point up to 250°C.
135
136
Indoor Air Quality: The Latest Sampling and Analytical Methods
Health Effects and Occurrences
Industrial exposures to volatile organic compounds (VOCs) are generally
10 to 100 times that of nonindustrial home and office environments. Home
and office environments are typically 2 to 100 times higher than that found
outside. A reasonable line of logic would dictate that industrial exposures
would result in more health complaints than home and office exposure. Yet
this is not the case.
Many environmental professionals ascribe the complaints to exposures to
a medley of chemicals and to the lack of adequate dilution in indoor air. The
chemicals are trapped and recycled with the close environments.
Indoor nonindustrial air environments may consist of up to three hundred
different chemicals, an amalgam that certainly complicates an investigation,
and the sources are certainly no less complicated. Indoor VOCs may originate from one or a combination of the following:
• Ambient outside air (e.g., benzene from automotive exhaust and vapor
release from gasoline service stations, especially in large cities)
• Off-gassing of chemicals from furnishings (e.g., formaldehyde from
desks made of particleboard)
• Emissions from office equipment (e.g., toners from copy machines)
• Cleaning and maintenance products
• Construction, demolition, and building renovation activities (e.g.,
painting the walls)
• Personal hygiene products (e.g., perfume)
• Poorly contained sewage gases (e.g., leaking sewer vents)
• Contaminated HVAC system (e.g., chemical storage in a return air
room)
• Pesticides and insecticides
• Environmental air pollution (e.g., automotive exhaust)
• Industrial emissions (e.g., particleboard manufacturing)
• Commercial activities (e.g., automotive painting, roof asphalting,
and dry cleaning exhausts)
For a list of some of the chemicals frequently found in indoor air quality and
their sources, see Tables 8.1 and 8.2.
Although the health effects of VOCs are chemical dependent, the effects
of low-level, nonindustrial exposures to the total organic compound composite generally encountered in indoor air quality are relatively consistent.
137
Volatile Organic Compounds
TABLE 8.1
Common Indoor VOCs and Their Sources
Pollutant
Formaldehyde
Benzene
Carbon Tetrachloride
Trichloroethylene
Tetrachloroethylene
Chloroform
1,2-Dichlorobenzene
1,3-Dichlorobenzene
1,4-Dichlorobenzene
Ethylbenzene
Toluene
Xylene
Indoor Sources
Germicide, pressed-wood products, foam insulation (UffI), hardwood
plywood, adhesives, particle board, laminates, paints, plastics,
carpeting, upholstered furniture coverings, gypsum board, joint
compounds, ceiling tiles and panels, nonlatex caulking compounds,
acid-cured wood coatings, wood paneling, plastic/melamine
paneling, vinyl floor tiles, parquet flooring
ETS, solvents, paints, stains, varnishes, fax machines, computer
terminals and printers, joint compounds, latex caulk, water-based
adhesives, wood paneling, carpets, floor tile adhesives, spot/textile
cleaners, Styrofoam, plastics, synthetic fibers
Solvents, refrigerant, aerosols, fire extinguishers, grease solvents
Solvents, dry-cleaned fabrics, upholstered furniture covers, printing inks,
paints, lacquers, varnishes, adhesives, fax machines, computer terminals
and printers, typewriter correction fluid, paint removers, spot removers
Dry-cleaned fabrics, upholstered furniture coverings, spot/textile
cleaners, fax machines, computer terminals and printers
Solvents, dyes, pesticides, fax machines, computer terminals and
printers, upholstered furniture cushions, chlorinated water
Dry-cleaning agent, degreaser, insecticides, carpeting
Insecticide
Deodorant, mold and mildew control, air fresheners/deodorizers,
toilet bowl and waste can deodorizers, mothballs and moth flakes
Styrene-related products, synthetic polymers, solvents, fax machines
computer terminals and printers, polyurethane, furniture polish,
joint compounds, latex and nonlatex parquet flooring
Solvent, perfumes, detergents, dyes, water-based adhesives, edgesealing, molding tape, wallpaper, joint compounds, calcium silica
sheet, vinyl-coated wallpaper, caulking compounds, paint, carpeting,
pressed-wood furnishings, vinyl floor tiles, paints (latex and
solvent-based), carpet adhesives, grease solvents
Solvents, dyes, insecticides, polyester fibers, adhesives, joint
compound, wallpaper, caulking compounds, varnish, resin and
enamel varnish, carpeting, wet-process photocopying, pressed-wood
products, gypsum board, water-based adhesives, grease solvents,
paints, carpet adhesives, vinyl floor tiles, polyurethane coatings
Symptoms typically involve one or a combination of the following:
•
•
•
•
Headache
Irritation of the eyes, nose, and throat
Lightheadedness
Nausea
138
Indoor Air Quality: The Latest Sampling and Analytical Methods
TABLE 8.2
Case Study of VOCs in Indoor Air, Suspect Sources, and Direct Reading
Instruments1
Limits of Concern
ACGIH
Direct Reading
ASHRAEa
Compound
(ppm)
(mg/m )
Pentane
Hexane
Cyclohexane
600
50
100
1700
176
343
7
Decane
Benzene
Toluene
Xylene
–
0.5
20
100
Limonene
Acetone
2-Butanone (MEK)
Methyl isobutyl
ketone
Tetrahydrofuran
Methyl cellosolve
(2-methoxyethanol)
Butyl cellosolve
(2-butoxyethanol)
Cellosolve
(2-ethoxyethanol)
Carbon tetrachloride
Tetrachloroethylene
(perchloroethylene)
1,1,1-Trichloroethane
Freon 113
n-Nonane
Methylene chloride
–
500
200
50
FIDb
–
natural gas
rubber cement
solvent
65%
75%
85%
8.40@10.6eV
4.30@10.6eV
1.40@106eV
–
1.6
75
431
–
0.02
0.3
0.7
copy toner
paints/gasoline
paints/gasoline
paints/gasoline
75%
150%
110%
115%
560d
1188
590
205
–
–
–
–
lemon-odor cleaner
–
solvent
60%
paints/solvent
80%
resins/solvent
100%
1.40@10.6eV
0.53@10.6eV
0.50@10.6eV
0.43-0.59@
10.6eV
–
1.10@10.6eV
0.86@10.6eV
0.80@10.6eV
50
148
0.01
0.32
–
–
plastic pipe cleaner
solvent/cleansers
–
–
1.70@10.6eV
2.40@10.6eV
20
97
–
solvent/cleansers
–
1.20@10.6eV
5
18
–
solvent/cleansers
–
2.40@10.6eV
5
25
31
170
0.04
0.035
solvent/cleansers
solvent/cleaners
10%
70%
1.70@11.7eV
0.57@10.6eV
55
1250
1050
174
1
office partitions
105%
coolant
90%
synthetics/gasoline 90%
polyurethane
90%
foam/plastics
aerosol
65%
propellants/
plastics
dry cleaning
fumigant/
113%
insecticide
0.98@11.7eV
1.0 @ 11.7eV
1.40@10.6eV
0.89@11.7eV
3
–
–
–
–
Trichloromethane
(chloroform)
10
49
0.03
1,4-Dichlorobenzene
(p-dichlorobenzene)
10
60
0.8
a
b
c
d
Suspect Instrument Response
Source(s)
10
1000
200
50
(mg/m )
3
From ASHRAE 189.1 List of Target Volatile Organic Compounds.
As calibrated to methane with Foxboro FID.
As calibrated to isobutylene with RAE Systems MultiRAE.
WHO recommended exposure limit in ASHRAE 62 (1989).2
PIDc
3.50@11.7eV
0.47@10.6eV
Volatile Organic Compounds
139
The EPA adds to the list some less commonly encountered symptoms:2
•
•
•
•
•
•
•
Nasal congestion
Coughing
Wheezing and worsening of asthma problems
Fatigue
Lethargy
Cognitive impairment
Personality change
Health effects resulting from industrial and commercial exposures involve
considerably higher exposures to a wide variety of known chemicals. The
health effects are more pronounced and chemical specific. If these higher
exposure levels are likely (e.g., exhausted chemicals from a manufacturing
operation), the health effects may be more extensive. The investigator should
assess impact based on the known health effects of the suspect chemical(s)
identified during the preliminary assessment. Exposures to different specifically identified chemicals will result in more specific symptoms than that
which is generalized for a total organic composite.
People who are chemically sensitive or chronically ill, the elderly, and
infants will also require special consideration, especially if exposures are
24 hour (e.g., residences and nursing homes). These people are not normally
located in office and other work environments.
Air Sampling Strategy
A clear, concise air sampling strategy is as important as the actual sampling. If samples do not represent the complaint times, area, and conditions, there is little point in taking a sample. It may appear obvious to
many that the when, where, and how are only logical. Yet logic is some­
times elusive.
When to Sample
At a minimum, samples should be taken during a time or times when complaints are their greatest and for a period of time sufficient to capture an
adequate sample. This may sound like a simple concept to many readers, yet
investigators often take samples during periods deemed most convenient for
the environmental professional. Sometimes these “convenient times” do not
fall within the time period during which there are complaints.
140
Indoor Air Quality: The Latest Sampling and Analytical Methods
Where to Sample
Identify an area or areas central to where complaints have occurred. At a
minimum, a worst-case air sample should be taken where the complaint(s)
are the greatest. A note of caution: The most complaints may be associated
more so with an individual than with the environment. In a large office
building, clusters of complaints are more reliable. In a small office or residence, the occupant(s) may be able to identify an area or areas they believe to
be the source of their perceived poor indoor air quality.
After determining the worst-case complaint area(s), determine if there is a
noncompliant area or area of perceived good indoor air quality. Where a noncompliant area can be identified, an indoor air sample should be considered.
There may be activities or conditions in the complaint area(s) that are not
encountered in the noncompliant area(s). These activities or conditions may
not be readily apparent or come to light unless the environmental professional compares the complaint sample results with the noncompliant sample
results. Noncomplaint area sampling is not vital, but it is a good practice.
It is, however, advisable that the environmental professional perform comparative outdoor air samples in conjunction with noncompliant control samples or as a stand alone. In large office buildings, outdoor air samples should
be taken at the HVAC fresh air intake for the area in question or wherever
there is air movement from outdoors to inside the building in the vicinity of
the complaints (e.g., high traffic entrances to a building and open windows).
In small offices and residences, there may not be an HVAC fresh air intake.
Where this is the case outdoor air samples may be taken outdoors in the
vicinity of high traffic entrances. Outdoor air comparison samples are vital
to interpreting the indoor air environment!
Worst-case air sample sites and comparative noncompliant/outdoor control
areas are not an easy task to identify. In large office buildings, questionnaires
and area charts areas are a must. For examples of comparative sampling, see
Figures 8.1 through 8.4.
As for physical placement, samples should be collected as area samples, not
personnel samples, unless the circumstances indicate otherwise. Placement
of the sampler should be within the breathing zone of those occupying the
area of concern, not in a corner or on a wall, but in the vicinity of their normal activity (e.g., sitting at a desk). Also consider the facility: A child-care
center will have a different placement than a mail-sorting center.
Take prolific notes regarding each sample site, documenting observations
and conditions (e.g., proximity of air supply diffusers, equipment, machines,
windows, doors, space heaters, pedestal fans, home air purifiers, plants, temperature, and humidity). If blowing directly on the sampler, the effects of
the air supply should be recorded. Stagnant air pockets may impact sample
results. Proximity of equipment (e.g., copy machines) and activities (e.g., gluing and painting) may be important. There is no such thing as too many
notes.
141
Volatile Organic Compounds
THF
300000
700000
THF
500000
300000
10.00
Time
14.00
18.00
PRODUCTION AREA
22.00
n-C14H30
n-C15H32
6.00
n-C11H24
2.00
Limonene
0
1,1,1-trichloroethane
Abundance
500000
100000
Abundance
n-C14H30
n-C15H32
OFFICE AREA
700000
100000
0
2.00
6.00
10.00
Time
14.00
18.00
22.00
FIGURE 8.1
Adjacent office area vs. point source production area. As demonstrated in the GC/MS printout,
some of the organics in the office space mimic that of the production area, but most of the VOCs
originated in the office area. (Courtesy of NIOSH, Cincinnati, Ohio)3
How to Sample
There is no one-size-fits-all technique for sampling volatile organics. As a
single panacea does not exist, the investigator should become familiar with
the various screening and sampling methods and apply them according to
specific project needs.
Rationale for Total VOC Screening
(As Opposed to Component Identification)
Screening for VOCs is used for determining need for more extensive, costly
approaches. The cost for the quantification of total VOCs is one-fifth to
one-tenth the cost for identification, and if a worst-case complaint area is
assessed, the number of samples to be analyzed can be minimized, again
Indoor Air Quality: The Latest Sampling and Analytical Methods
2.00
6.00
Ethanol
Abundance
Hexane
500000
300000
100000
0
14.00
Limonene
Dimethylbenzene
methanol
18.00
OUTDOOR CONTROL
900000
700000
10.00
Time
2.00
6.00
Toluene
100000
0
Ethanol
300000
Hexane
500000
Toluene
Abundance
700000
Methyl styrene
OFFICE AREA
900000
Methyl methacrylate
142
10.00
Time
14.00
18.00
FIGURE 8.2
Office area vs. outdoor control. As demonstrated in the GC/MS printout, some of the organics
in the office area mimic the outside area with the addition of indoor source VOCs, but most
originated in the office space. (Courtesy of NIOSH, Cincinnati, Ohio)3
keeping down the overall project cost. If the results are low additional analytical fees may be circumvented. This brings us to the all-consuming question: How low is “low,” and what are acceptable risks?
There are no mandated acceptable limits for total VOCs. Thus, the environmental professional must decide on an action limit to serve as a “go, no-go”
decision guide prior to proceeding with the expense of identification and
more extensive sampling. There are no established acceptable limits for total
VOCs. Thus, the environmental professional must decide on his/her action
limit prior to proceeding.
Most environmental professionals use an action level of 500 µg/m3 (0.5 mg/
3
m ). This 500 µg/m3 limit has been adopted by several state governments and
has become the LEED maximum concentration, or limit, for total VOCs. Yet it
is noteworthy that some professionals choose an even lower action level.
For some VOCs toxic exposure limits are not as low as irritation exposure
levels, and not all irritant/toxic VOCs have an exposure limit. For example,
phenol has an American Conference of Governmental Industrial Hygienists
(ACGIH) exposure limit of 5 ppm (19 mg/m3). Some sensitive individuals
143
Volatile Organic Compounds
COMPLAINT AREA
1000000
C6 alkanes
Limonene
Abundance
1400000
600000
200000
2.00
6.00
1,1,1-trichloroethane
Abundance
14.00
NONCOMPLAINT AREA
1400000
1000000
600000
200000
0
10.00
Time
2.00
6.00
Limonene
0
10.00
Time
14.00
FIGURE 8.3
Complaint area vs. noncomplaint area. As demonstrated in the GC/MS printout, the source of
the VOCs was found to be generated in the vicinity of the complaint area, not in the noncompliant area and not outdoors. (Courtesy of NIOSH, Cincinnati, Ohio)3
can experience irritation at levels as low as 0.19 mg/m3. If the 0.5 mg/m3
action level were applied and no further VOC identification were indicated,
phenol would not be identified and the search for unknowns would be misdirected to other areas. There are also many chemicals for which there are no
established exposure limits. 1-Methyl-2-pyrrolidinone, an irritant thought to
be associated with 4-phenylcyclohexene and styrene butadiene rubber latex
carpet backing, does not have any published exposure limits. Thus, some
professionals choose a limit of 250 µg/m3 (0.25 mg/m3).
Air Sampling and Analytical Methodologies
As all environmental professionals are not the same, air sampling and analytical methods differ from one laboratory to the next. Air sampling and analytical methods for VOCs, identified and not identified, have been developed
and published by the Environmental Protection Agency (EPA), Occupational
144
Indoor Air Quality: The Latest Sampling and Analytical Methods
1000000
0
2.00
6.00
2-Ethylhexyl acrylate
18.00
22.00
OUTSIDE CONTROL
5000000
Toluene
Abundance
7000000
14.00
Time
1-Methyl-2-pyrrolidinone
Styrene
10.00
Xylene
Toluene
p-Dioxane
Methyl isobutyl ketone
3000000
Methyl ethyl ketone
5000000
INSIDE NEW TRUCK
Trichlorofluoromethane
Abundance
7000000
3000000
1000000
0
2.00
6.00
10.00
14.00
Time
18.00
22.00
FIGURE 8.4
Inside new truck vs. outside control. As demonstrated in the GC/MS printout, toluene was
found outside the truck, and all the other VOCs originated inside the truck. (Courtesy of
NIOSH, Cincinnati, Ohio)3
Safety and Health Administration (OSHA), and National Institute for
Occupational Safety and Health (NIOSH). Beyond the government agencies
commercial laboratories develop their own protocols in order to accommodate special client needs and advance new technologies, and instrumentation technology is constantly evolving to accommodate requirements of
environmental professions.
All commercial laboratories are not the same. They have different capabilities and depth of knowledge. Many laboratories perform very basic chemical
analyses (e.g., solid sorbent analysis by gas chromatography). Some perform
more extensive analyses (e.g., solid sorbent analysis with gas chromatography/mass spectrometry), and a limited number of these provide evacuated
containers. In brief, few laboratories can do it all, and even fewer perform
research and develop methods to accommodate special client requests. The
information herein is intended to familiarize the reader with published
methodologies and limitations.
Volatile Organic Compounds
145
Solid Sorbents and Air Sampling Pumps
The preferred, most reliable solid sorbent sampling technique, both qualitatively (identification) and quantitatively (airborne levels determined), occurs
where the organic compounds have already been identified. Either specific
compounds are known to be present (e.g., toluene from recently applied
paint), or they are suspect (e.g., potential 1,1,1-trichloroethane from office
partitions). Suspect chemicals are often targeted based on odors, complaint
symptoms, or probable sources. Yet all too often the offending chemical is
unknown and there are multiple suspects, so screening for total VOCs and
identification of components becomes the option of wise resort.
Solid sorbent sampling is useful for both screening for total VOCs and for
identification of components. Air sampling is an active approach whereby
air is drawn through a solid sorbent that captures (i.e., collects) airborne contaminants that are then analyzed by a laboratory. The two most widely used
methods are NIOSH Method 1500 and EPA Method TO-17. Although the EPA
TO-17 is all inclusive for most VOCs, NIOSH 1500 (which has limited capture
ability, limited VOC retrieval) has been the most frequently used method,
especially for screening, due to convenience and familiarity.
NIOSH Method 1500
NIOSH Method 1500 for hydrocarbons involves collection of air samples
using activated coconut shell charcoal (contained within a glass tube), desorption with carbon disulfide, and analysis by gas chromatography using a
flame ionization detector. Many VOCs that are generally of concern in indoor
air quality testing are adsorbed onto (captured by) charcoal solid sorbent,
but some are not collected. If elevated levels of any given VOC air contaminant are not captured and if that specific VOC is the source of complaints,
the uncollected VOC will not contribute to the total VOCs, and it cannot be
salvaged if further identification of the total VOC components is indicated
during the screening process. It will go undetected. For example, phenol
off-gassing from phenol-formaldehyde particleboard could cause irritation,
while the capture sorbent for phenol is XAD-2 solid sorbent, not charcoal.
In NIOSH 1500 the captured VOCs are desorbed with carbon disulfide.
Whereas carbon disulfide is very effective at extracting captured VOCs,
there are some that require a different solvent. If the proper solvent is not
used some VOCs will be missed. For instance, acrylonitrile requires methanol for desorption. If it was collected but not retrieved from the solid sorbent,
exposures to the eye, nose, and throat irritant acrylonitrile will remain undetected and undocumented.
To go one step further, in a 1993 study performed by NIOSH the effectiveness of thermal desorption (e.g., EPA Method TO-17) over chemical desorption was challenged. Two separate sorbents were used to sample within
146
Indoor Air Quality: The Latest Sampling and Analytical Methods
the same time period and same sample site (e.g., a rubber molding facility).
One was sampled by thermal desorption tube with a carbon-based sorbent
and analyzed by gas chromatography/mass spectrometry (GC/MS). The
other was sampled by charcoal tube, chemically desorbed, and analyzed
by GC/MS. The results favored thermal desorption sampling and analytical approach over the other.2 Compounds missed in the chemically desorbed charcoal tube included aliphatic amines, sulfur dioxide, and carbon
disulfide. Since it is used as the desorption compound for most chemical
extractions from charcoal tubes, carbon disulfide would have been overlooked as an indoor air contaminant had chemical desorption be used. See
Figure 8.5.
The failures of NIOSH 1500 can be troubling. Too many volatile organic
compounds that could cause health complaints may be overlooked. The alternative, EPA Method TO-17 (also NIOSH Method 2549), is more all-inclusive
and more reliable. However, TO-17 is three to ten times more costly than
NIOSH 1500.
THERMAL DESORPTION
Abundance
450000
C10-C12 branched
alkanes
350000
250000
150000
50000
0
5.00
7.00
11.00
13.00
Time
15.00
CHEMICAL DESORPTION
(Charcoal Desorbed
by Carbon Disulfide Solvent)
450000
Abundance
9.00
350000
17.00
19.00
C10-C12 branched
alkanes
250000
150000
50000
0
5.00
7.00
9.00
11.00
13.00
Time
15.00
17.00
19.00
FIGURE 8.5
Thermal desorption vs. chemical desorption. The GC/MS printout demonstrates the greater
efficiency of thermal desorption over that of chemical desorption. (Courtesy of NIOSH,
Cincinnati, Ohio)3
Volatile Organic Compounds
147
A summary of NIOSH Method 1500 follows:
•
•
•
•
•
•
•
•
Equipment: air sampling pump
Capture media: coconut shell charcoal or Anasorb® 747
Flow rate: 50 to 200 mL/min.
Air volume limits: 2–30 liters
Desorption: carbon disulfide
Reference standard for TVOC: toluene (variable by laboratory)
Field blanks: minimum of one for every ten samples
Analysis: GC–FID (C3–C17; mostly nonpolar organics with boiling
point <220°C)
• Limit of detection: 246 ng/sample (variable by laboratory); 68.3 µg/m3
(or 18.1 ppbv toluene) based on four-hour sample at 50 lpm as per
OSHA Method 111)
• Special handling and shipping instructions: none
EPA Method TO-17
In EPA Method TO-17, the solid sorbent is a thermal desorption tube (e.g.,
Carbopak™) that is either commercially available or specially prepared by
the laboratory (e.g., packed and conditioned in stainless steel or polymeric
tubes). The multiple sorbent (containing three or more broad spectrum sorbents) is more all inclusive and captures many VOCs that are not collected
by charcoal tube sampling (e.g., NIOSH 1500) as well as all those that are
collected by charcoal sorbent, and many multiple sorbents collect some of
the heavier semi-volatile organic compounds (with a boiling point greater
than 220°C). For example, many multiple sorbents collect the eye and mucus
membrane irritant 1,3-butadiene (a light molecular weight organic that is not
captured by charcoal), and most multiple sorbents capture the carpet emissions irritant 4-phenylcyclohexene (boiling point: 243°C) which is not otherwise collected by charcoal nor retrieved from canisters. See Figure 8.6.
Another advantage to TO-17 is that desorption is not solvent dependent,
whereas component retrieval and analysis is desorption solvent dependent
when sampling with charcoal sorbents. The multiple sorbent tube is hooked
up directly to the GC/MS and heated to drive all the captured chemicals
from the tube. Once again, the single charcoal sorbent does not allow for
analysis of all that has been captured.
Analysis is then performed in accordance with client instructions. Here
again each laboratory has a different list of VOCs to be analyzed with specific
reference standards. Each list is based on perceived client concerns (e.g., toxic
VOC, odors, or irritants), multiple sorbent type, and experience. Most laboratories also perform a library search in order to identify other compounds
148
2.00
6.00
0
2.00
Octane
Toluene
Phenol
Decane
Limonene
14.00
Time
Toluene
Heptane
MIBK
1,1,1-TCE
Benzene
Hexane
Acetone
2000000
6.00
Methylene chloride
6000000
2.00
Ethanol
Acetone
Abundance
Abundance
0
10.00
2nd LAYER
(Traps Moderately Volatile Organic Compounds)
6000000
2000000
Time
10.00
14.00
3rd LAYER
(Traps Most Volatile Organic Compounds)
1,1,1-TCE
0
Heptane
MIBK
2000000
Benzene
6000000
Hexane
Abundance
1st LAYER
(Traps Least Volatile Organic Compounds)
Butyl cellosolve
Indoor Air Quality: The Latest Sampling and Analytical Methods
6.00
Time
10.00
14.00
FIGURE 8.6
Multibed thermal desorption. The GC/MS printout demonstrates volatile organic compounds
captured in each of the layers. (Courtesy of NIOSH, Cincinnati, Ohio)3
that may not be on the list. A library search may include up to 750,000 chemicals. Much like illegal designer drugs, if you limit a search to that which has
been of the past, you may miss that which will be in the future.
The analytical cost, once again, is the greatest objection, and quantified
identification of components is more costly than analysis for total VOCs. On
the other hand, qualitative identification of the components may not result
in an additional fee. Yet the benefit of component identification of significant
contributors to the total VOC medley is a viable compromise while keeping
the cost down.
Another downside to the TO-17 method is that once the sorbent sample has
been thermally desorbed, the captured VOCs are gone—unless the laboratory undergoes splitting/re-collection of the samples as they are analyzed by
the GC/MS. The latter is not performed by all laboratories. Also, if a sample
is being processed and should the electricity surge or fail, the sample may be
lost. It cannot be retrieved. This may happen one time in one hundred, but it
does happen. Dual sampling is advisable.
Volatile Organic Compounds
149
A summary of EPA Method TO-17 follows:
• Equipment: air sampling pump
• Capture media: thermal desorption tube (e.g., Carbopak™), which
generally requires laboratory cleaning and conditioning
• Flow rate (TO-17): 10 to 50 mL/min.
• Flow rate (laboratory experience/preference): 50–100 mL/min.
• Air volume limits: 1–6 liter (variable higher limits based on multibed
sorbent, and required reporting limits may be as high as 10 liters)
• Desorption: thermal desorption
• Reference standard for total VOC: toluene (variable by laboratory)
• Field blanks: minimum of one for up to ten samples in any given
sampling period
• Analysis: TD–GC–MS (C5–C17; polar and nonpolar organics with
boiling point <250°C)
• Limit of detection: 0.1 ppm/1 liter sample; 0.4 µg/m3 (toluene) based
on a 1 liter sample
• Special handling and shipping instructions: laboratory dependent
(some require ice pack for shipping)
All VOC analyses require a reference standard for the purpose of quantifying each of the chemical components. The reference standard for total
VOCs (a mix of unknown components) is generally toluene (or an organic
that has a similar molecular weight such as n-hexane). Laboratory preferences do vary, and the reference standard used for quantifying total VOCs
affects the reported results. True quantification can only be obtained by
using a reference compound for each component. Thus, quantification of
total VOCs is only a “ballpark number” and varies by laboratory and reference standard used.
Passive Organic Vapor Monitors
Passive air diffusion monitors are lightweight badge assemblies that rely on
natural air currents (rather than air sampling pumps) to allow air to diffuse
through a protective membrane and be collected by a solid sorbent contained
within a badge (e.g., disk-shaped plastic container). Organic vapor monitors
are easy to use but slow, and they are similarly limited by the same parameters as air sampling using charcoal (e.g., NIOSH 1500).
For more than twenty years organic vapor monitors have had a charcoal
sorbent that adsorbs organic vapors from the air at a low capture rate. Each
compound has a unique sample rate and diffusion coefficient that is used
to calculate the final concentration of that component. For example, the 3M
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Organic Vapor Monitor sampling rate for p-tert-butyltoluene is 20.7 mL/
min., and the sampling rate for acrylonitrile is 48.2 mL/min.4
When there are multiple components some compounds will displace others and the full spectrum of indoor air VOCs may disappear. For instance,
nonpolar n-hexane will displace the more polar isopropanol.
As all passive monitors rely on diffusion and natural air movement, there
is a minimum air flow necessary in order to prevent “starvation” at the surface of the sampler. The minimum air movement, around 20 feet per second,
is generally quite low but the environmental professional should be aware
of this limitation. For example, a building that has been vacated and has no
air movement, the air movement may be nonexistent and passive sampling
is likely to be ineffective. Air starvation is a minor limitation, not normally
encountered when using an air sampling pump.
Another limitation of the passive monitors is sampling rate and sample
duration. For detection levels comparable to air sampling pump flow rates of
50 liters/min. and 200 liters/min., an organic vapor monitor sampling time
must be two times and eight times the pump air sampling duration (based
on the sampling rate range of 20.7 to 48.2 liters/min.). For example, an organic
vapor monitor would have to be exposed for eight hours in order to collect
the same sample as a four-hour air sampling flow rate of 50 liters/min.
Analysis of organic vapor monitors is addressed in OSHA Method 111, which is
similartoNIOSHMethod1500.Desorptionisby60/40N,N-dimethylformamide/
carbon disulfide, and analysis is by GC–FID. All things considered, the organic
vapor monitor does require a longer sampling duration.
A summary of 3M and SKC Organic Vapor Monitor Method follows:
• Equipment: organic vapor monitor (with the protective membrane
intact during sampling)
• Capture media: charcoal
• Air volume limits: 2–30 liters
• Desorption: carbon disulfide
• Reference standard: toluene (variable by laboratory)
• Field blank: minimum of one for up to ten samples in any given
sampling period
• Analysis: GC–FID (C3–C17; mostly nonpolar organics with boiling
point <220°C)
• Limit of detection: 246 ng/sample; 309 µg/m3 (or 82 ppbv toluene) based
on four-hour sample with a 3M 3520 (as per OSHA Method 111)
• Special handling and shipping instructions: none
In order to address the sampling duration discrepancies with passive monitors, the Radiello Passive Sampling System is an emerging technology in the
U.S. Having been used in Europe for more than ten years for environmental
Volatile Organic Compounds
151
and indoor air quality sampling, the Radiello has not been acknowledged
by the EPA or NIOSH. It is, however, being introduced by some laboratories
within the U.S.
The Radiello passive monitors are typically tube-shaped and have a higher
diffusion rate than that of the SKC and 3M Organic Vapor Monitors. Two of
the more commonly used Radiello passive monitors allege rapid sampling
times. The Radiello (RAD) 130 is a passive diffusion monitor that is comparable to charcoal sorbent organic vapor monitor. Yet the RAD 130 alleges
a faster sampling time. The RAD 145 is an interesting variation to passive
sampling. It has been adapted to allow for diffusion onto a multibed sorbent
and can be used as a passive sampler for EPA Method TO-17. The RAD 145
sampler can be thermally desorbed and analyzed by GC/MS.
According to some U.S. laboratories the RAD 145 is a mid-range (C5–C10)
sample device and is being used in some indoor air quality studies. Its efficacy has yet to be fully tested, and the Radiello diffusion monitor will not
collect the higher molecular weight, higher boiling point compounds such
at that which is encountered in carpet emissions. In other words, it will not
collect 4-phenylcyclohexene.
As of the writing of this book the Radiello passive diffusion samplers have
yet to be recognized by the EPA and have not been widely accepted for use
in indoor air quality studies within the United States. Should one desire to
utilize this method the number of laboratories performing this analysis is
limited, and the approach is not widely recognized by the environmental
professionals.
Evacuated Ambient Air Containers
In accordance with EPA Method TO-15 sample collection is performed by
evacuated air containers (also whole air samplers) that suck in and retain
ambient air, all organic components. When a client asks, “Can’t you just suck
in all the air?” Well, yes, you can! It is the analytical procedure that limits
identification of all components in the air. For example, formaldehyde may
be present in the collected air, but it is poorly retrieved and analyzed by
GC/MS due in part to its low molecular weight. Aldehydes are best captured by specialty sampling media and analyzed by different methods (see
Chapter 12, “Formaldehyde”).
Heavier VOCs tend to settle in the ambient air containers and may settle
and be difficult to retrieve. Such is the case with 4-phenylcyclohexene. The
multibed sorbents (e.g., TO-17) can capture and release the heavier VOCs.
Also, inorganics may be retained within the ambient air container but are
not analyzed by GC/MS.
Evacuated air containers include evacuated canisters (e.g., SUMMA-like
canister) and ambient air sampling bags (e.g., Tedlar® bag). While the others
are adaptations, stainless steel evacuated air canisters are the equipment of
choice as described in EPA Method TO-15.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Whole Air Canisters
Stainless-steel whole air canisters come in various sizes (ranging from 0.85 to
33 liters in volume). The most common size used in indoor air quality studies is 6 liters. The original SUMMA® stainless steel canisters were chemically
treated to prevent rusting and minimize organic adherence to the surface
of the container. Yet sample stability was not all that it could be. Today’s
stainless steel canisters (sometimes referred to as SUMMA-like canisters)
are electropolished to bring the nickel and chromium to the surface, making
the inside of the canister inert with a mirror-like finish. Silica-treated stainless steel canisters are electropolished then treated with fused silica, a tough
interior glass-like surface that will not crack or break under rough field and
shipment handling. Wherein ideal for TO-15, electropolished canisters are
unreliable for collecting sulfur-containing/brominated compounds that tend
to adsorb, or stick, to the inner surface of electroplated stainless steel canisters
and are poorly retrieved for analysis. Yet for every problem there is a solution.
The solution is the special silica-treated evacuated canister. See Figure 8.7.
FIGURE 8.7
SUMMA-like evacuated air canister—silica-coated canister best for low-level detection of sulfur-containing compounds. (Courtesy of Restek Corporation, Bellefonte, Pennsylvania.)
Volatile Organic Compounds
153
According to Restek, SilcoCan canisters provide a stable environment for
analysis of sulfur-containing VOCs as low as 1 ppbv. In one study involving the same air collection by two different canisters, the silica-treated canister analysis provided a detection of 5 ppbv hydrogen sulfide, whereas the
electropolished canister provided a detection of 100 ppbv. The odor threshold for hydrogen sulfide is less than 9 ppbv.5 If a sulfide-containing organic
is contributing to the odor in an indoor air quality study, the retrieval from
an electropolished canister is not as good as that of a silica-treated canister.
Hence, if an electropolished canister is used instead of a silico-treated canister, the detection will likely not be low enough to identify any component
sulfur-containing compounds (e.g., mercaptans or off-gassing hydrogen sulfide from tainted Chinese drywall). Wherein sulfur-containing compounds
are present in levels below 5 ppbv, there are no methods available that can
trump this claim.
Prior to use each canister must be cleaned, conditioned, and prepared by
a laboratory that has canister analytical capabilities. The canister cleaning
process takes up to 24 hours per canister, so the laboratory will require some
lead time. As part of the planning process, the inlet may also be fitted with a
flow control, or critical orifice, if a predetermined extended sampling duration (e.g., four hours) is required. Otherwise, without a calibrated critical
orifice (provided by the laboratory), a grab sample will be collected. A grab
sample will take less than 30 seconds in a 6-liter canister.
When the valve is opened the ambient air is drawn into the canister by
vacuum until the canister pressure and ambient air pressure are equal.
To determine if this has occurred refer to the canister gauge that is available through the laboratory (upon special request). Start and finish times
should be recorded along with pertinent sample conditions (e.g., temperature, relative humidity, and barometric pressure if available) and location
details.
Collected air samples are auto injected into a GC/MS. Some laboratories
cryogenically treat each sample as it is injected to concentrate the sample and
attain a greater level of detection. The amount of air sample injected may be
anywhere from a 100-milliliter portion to 1 liter of the sample, depending on
sample volume collected, the laboratory standard procedures, and whether
the sample is to be cryogenically concentrated. The higher the volume of air
sampled, the higher the limit of detection. Some laboratories will analyze
200 to 250 milliliters of air if not cryogenically treated, finding that the limit
of detection is more than sufficient to not require concentration. Other laboratories choose to or the environmental professional may request a sample
be cryogenically concentrated whereby a 1-liter of air is cryofocused to get
greater detection limits. Thus, 1 liter of air is the greatest volume of air that
can be analyzed in accordance with EPA TO-15. Wherein the canister volume exceeds the air volume analyzed, air samples can be reanalyzed should
the first analysis meet with misfortune or should the environmental professional require additional analyses.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
A summary of EPA Method TO-15 follows:
• Equipment: evacuated air container
• Capture media: not applicable
• Flow rate: instant grab sample or long duration up to three days
(flow control valve)
• Air canister size: 1–6 liters
• Desorption: automated injection of 200 milliliters of sampled air,
irrespective of canister size
• Reference standard: toluene (variable by laboratory) for total VOCs
• Analysis: GC/MS (C3–C12; organics with boiling point <220°C)
• Limit of detection: 0.5 ppbv/sample (variable by laboratory)
• Special handling and shipping instructions: none
A word of caution is in order for requesting cryofocusing on an indoor air
quality sample. The detection levels for a straight GC/MS analysis are extremely
low already without cryogenic concentration, and wherein a component VOC
approached the ppmv concentration, the analysis of similar low level organic
components may be obscured as cryofocusing detection limits dip parts per
trillion (pptv). Cryofocusing is not needed wherein systemic health symptoms
and irritation are the concerns. The systemic health concerns and irritation levels will be in the ppb or ppm, not ppt, range. Yet cryofocusing may be beneficial
where the odor threshold of some VOCs dips below 1 ppb. For example, the
mean odor threshold for mercaptans has been reported as 500 ppt, individually as low as 2 ppt. The mean odor threshold for ethyl acrylate is 240 ppt. The
odors are described as that of rotten cabbage and sweet/ester/plastic, respectively.5 Could not the new car smell be due in part to ethyl acrylate?
Ambient Air Sampling Bags
Ambient air sample collection bags are special sampling equipment con­
structed of synthetic material (e.g., Tedlar and Teflon). At first blush the sampling bags are inexpensive to purchase and can be purchased in bulk for
shortsighted planning projects. Simple Simon stops here!
Organic components may adhere to the surface of the bag or may off-gas
from the synthetic collection bag, resulting in unreliable findings. In theory,
the analysis and results would be comparable to that of a stainless steel evacuated air canister if the sample collection does not result in losses.
A chemically nonreactive, sample bag (0.5 to 120 liters) is installed and
sealed within an airtight container that is larger than the fully inflated sampling bag and has chemically nonreactive, valve-fitted inlet and outlet ports.
Where the inlet is connected to the sample bag the outlet is connected to
a vacuum pump. As the vacuum pump draws a vacuum inside the sealed
Volatile Organic Compounds
155
FIGURE 8.8
VacBag sampler system. (Courtesy of Apex Instruments, Fuguay-Varina, North Carolina.)
container, the sample bag draws in ambient air to replace the void that is
created inside the sealed container. In this manner, the collected air does not
pass through a previously contaminated sampling pump, and the limited
contact with various surfaces (to which chemical may adhere) that might
result the loss of chemicals from the air being sampled. For an example of a
commercially available “integrated bag sampler,” see Figure 8.8. Should you
choose to forgo the expense of a commercial unit, many environmental professionals build their own homegrown variety with Teflon connectors sealed
to the interior of airtight plastic container (e.g., a Tupperware container or
trash can).6
The sample duration may theoretically be controlled by the flow rate of
the sampling pump, and upon completion the bag valve stem is closed. The
container seal is broken, and the sample is removed/prepared for shipping.
Be sure to record all sampling conditions (e.g., sample name or number, temperature, humidity, and barometric pressure) and sample location(s) as previously discussed, and ship the container to a laboratory. Some people who
use this system, however, have commented that time integrated sampling
“never works out to fill the bag in the amount of time you think.”7
Shipping further poses problems that are unique to this method. Due to
the failed rigidity of the sampling bag an extreme change in atmospheric
pressure (which does occur in air transportation) may result in an expansion
Indoor Air Quality: The Latest Sampling and Analytical Methods
TVOC as Toluene Concentration, μg/m3
156
2000
Canister
Tenax
Radiello
Charcoal
1500
1000
500
0
FIGURE 8.9
Total VOC comparison of sampling methods.8 (Courtesy of Columbia Analytical Services,
Kelso, Washington.)
of the bag to the point where its integrity is compromised (e.g., overfilled,
damaged, or leaking). It is not unusual for sample bags to arrive at their destination with nothing inside. The way to avoid this problem is to collect only
half the capacity of the bag, ship the bag in a rigid, pressurized container, or
physically transport the sample(s) on land to the laboratory.
Analytical Comparisons
In a comparison study three total VOC sampling and analytical methods
were performed in tandem at thirteen indoor locations.8 The methods were
TO-15 (i.e., canister collection) and two variations of TO-17 (i.e., single sorbent
Tenax® TA with thermal desorption and Radiello 145 with thermal desorption), and the findings were sporadic. The canister total VOC concentrations
were two to three times greater than the other methods in two locations and
10 percent to 25 percent greater than the others in two other locations. The
Tenax concentrations were 10 percent to 25 percent greater than the canisters and double that of the Radiello in four locations. The remaining five
locations were somewhat comparable with a 5 percent to 10 percent greater
concentration favoring the Radiello. Half of these locations with canister and
Tenax dominating exceeded the 500 µg/m3 limit (as compared to toluene).
Thus, there appears to be no consistent pattern between sampling methods. The significance of these patterns is indeed elusive. See Table 8.3. In
confusion, there may be some sanity in the results of the study! One may
safely conclude that each indoor air environment, each sample location has
157
Volatile Organic Compounds
TABLE 8.3
Characterization of Common Volatile Organics
Aromatic Hydrocarbons
benzene
toluene
o-, m-, p-xylene
Aliphatic Hydrocarbons
n-pentane
n-hexane
n-heptane
n-octane
n-decane
Ketones
acetone
butanone (MEK)
methyl isobutyl ketone
cyclohexanone
Alcohols
methanol
ethanol
isopropanol
butanol
Glycol Ethers
butyl cellosolve
diethylene glycol ethyl
ether
Phenolics
phenol
cresol
2-, 3-, 4-methylphenol
Chlorinated Hydrocarbons
methylene chloride
1,1,1-trichloroethane
perchloroethylene (tetrachloroethane)
o-, p-dichlorobenzenes
1,1,2-trichloro-1,2,2-trifloroethane (Freon)
Terpenes
d-limonene
turpentine (pinenes)
Aldehydes
hexanal
benzaldehyde
noanal
Acetates
ethyl acetate
butyl acetate
amyl acetate
Other
Octamethylcyclotetrasioxane
different VOC components—different volatility and different polar properties. Without knowing the components, it is difficult to draw a clear conclusion. The choice between canister and solid sorbent sampling for total VOCs
appears to be irrelevant.
Yet Tenax is a single sorbent and performs well with higher boiling point
VOCs but does not capture the broad range of chemicals based on boiling
point and molecular weight that a multiple solid sorbent captures. Thermal
desorbed solid sorbents yield light, medium, and high molecular weight
compounds with lower boiling points up to 250°C (e.g., components of low,
moderate, and high volatility) and are not limited to the higher boiling
points only. The comparison study did not include multiple solid sorbent
with thermal desorption. Therefore, it is likely that if included in the study
samples collected on Carbopak™, a multiple sorbent, and analyzed by TO-17,
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Indoor Air Quality: The Latest Sampling and Analytical Methods
the levels would have demonstrated greater total VOC concentrations in all
sample locations in the study. Some laboratories indicate that clients who use
this method for total VOC screening frequently exceed the 500 mg/m3 limit
as set forth by some environmental professionals. This is likely due to high
molecular weight, semivolatile organics (boiling point: 220–250°C) that are
associated with this method and excluded from others.9
As for component identification, EPA Method TO-17 is the best all around
approach for collection, analysis, and detection of a broad range of VOCs
(C5–C17) with a boiling point up to 250°C. While it is one of the most expensive and unforgiving methods, TO-17 is the most powerful tool of identifying unknowns and the only method that includes 4-phenylcyclohexene in
the analysis.
EPA Method TO-15 (i.e., canister sampling) is a good all-around approach
for collection, analysis, and detection of a broad range of VOCs (C3–C12)
with a boiling point up to 220°C. Although the cost for analysis is high, canister analysis is more forgiving than that of multibed thermal desorption
sampling should the laboratory misapply or lose your sample due to a glitch
in the processing. Canister analyses can be reanalyzed; however, if there was
no duplicate, samples collected in accordance with TO-17 (i.e., multibed thermal desorption) will be lost and must be resampled. This is not the case with
TO-15.
Also there are a significant number of lightweight VOCs in a building that
are normal to indoor air environments that the environmental professional
may or may not want to identify. Only canister (and charcoal sorbent) sampling
results in the capture and analyses of lightweight VOCs. For example, acetone
from fingernail polish remover and isopropyl alcohol in rubbing alcohol are
typically encountered in occupied spaces in relatively high concentrations. In
a total VOC screening the lightweight, normally present VOCs will likely contribute concentrations in excess of the 500 mg/m3 total VOC action limit.
Whereas TO-15 includes the highly volatile and moderately volatile VOCs,
TO-17 includes moderately volatile and less volatile VOCs. To completely
cover all bases wherein price is no object, component sampling and analysis
by both EPA Methods TO-15 and TO-17 is recommended. This dynamic duo
can be expensive, but the results are legally bulletproof.
Lastly, keep in mind that lower-level sulfur-containing and brominated
VOCs are not recoverable by either method unless a special silicon-coated
canister is used for TO-15. When sulfur-containing mercaptans are suspect,
the silicon-coated canister is superior to a canister that has not been coated.
Helpful Hints
VOC sampling is best performed in low-humidity environments. Although
the environmental professional rarely has a choice, remember to record
temperature and relative humidity when taking air samples. Solid sorbent
capture of polar VOCs becomes compromised in high humidity as does
Volatile Organic Compounds
159
evacuated canisters, or whole air sampling, demonstrate difficulties during
the analysis. The laboratory attempts to control the moisture with a purge
and trap system within the GC/MS, but extremely high humidity levels can
not be completely purged. Thus, high humidity may skew the results.
Each laboratory is different in capability, experience, equipment, and
analytical approach. The reference standards for total VOCs vary, and the
detection limits for components vary. The lists of VOCs with reference
standards vary, and the GC/MS library databases vary. All laboratories
require preparation and precleaning/preconditioning of canisters prior to
sampling, and most laboratories request multibed solid sorbent for thermal desorption be preconditioned, even if the sorbent has been newly purchased. Most laboratories provide the environmental professional with
sampling supplies, and some are limited. To avoid confusion and questionable/undecipherable sample results, seek clarification from your laboratory
prior to sampling.
Upon VOC identification by GC/MS, sampling may be performed for the
individual chemicals at a considerably reduced cost. Further sampling may
provide information regarding: (1) locations/areas impacted; (2) source tracking; (3) HVAC contamination; and (4) individual exposures. As the methods
are highly variable, individual chemical sampling should be performed by
an industrial hygienist trained in different sampling methods.
As of the writing of the book, there are several new products (e.g., deactivated glass bottles) on the market that allege great promise in the area of
VOC sampling. As they are not widely accepted and available through most
laboratories, I have chosen not to elaborate.
In the preceding editions to this book, other sampling products were mentioned as well. Due to their limited accessibility, obsolescence, and failed
recognition/use by environmental professionals/laboratories, some of the
previously mentioned products (e.g., ambient air samplers and MSA evacuated cans) are no longer included in this book.
Interpretation of Results
Where the total VOC screening is performed, the investigator decides on
an acceptable/action limit, based on professional judgment. Professional
judgment is based on experience and guidelines set forth by others as discussed in previous sections. To recap the guidelines discussed in Screening
Procedures, many investigators choose one of the following:
• A limit of 500 µg/m3, as compared to toluene, required for LEED
total VOC sampling
• A limit of 250 µg/m3, guideline of choice by a limited few where
odors are a main concern (due to the very low odor threshold levels
of many organic compounds, well below that which results in systemic complaints)
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Indoor Air Quality: The Latest Sampling and Analytical Methods
The investigator may choose a stricter limit or a less restrictive limit. Once
again, the total VOC screening procedures are not intended to regulate but
to investigate. Screening is performed to establish a limit whereby further
sampling is indicated.
Where the airborne levels of total VOCs are less than the limit decided on
by the investigator, no further sampling or analyses is indicated. If, however,
the screening levels exceed the limits, sampling for component identification should be performed. Once identified, the VOCs may be assessed on the
basis of the identified components.
The acceptable/action limit for known chemicals in indoor air environments must, once again, be based on professional judgment. The investigator
may choose to use any one of the following:
• The ACGIH occupational exposure guidelines for specific chemicals
(not recommended for use where 24-hour exposures may occur)
• The NIOSH occupational exposure guidelines for specific chemicals
(generally more stringent than the ACGIH guidelines and not recommended for use where 24-hour exposures may occur)
• One-tenth of the ACGIIH guidelines for specific chemicals
• Published sensory irritation levels for specific chemicals
• The ASHRAE 189.1 limits for specific chemicals (limits set at twice
the California RELs from the Standard Method for the Testing and
Evaluation of Volatile Organic Emissions from Indoor Sources Using
Environmental Chambers)10
Where limit(s) are exceeded, comparative samples become an important
piece of the pie. These include the following:
• Compare problem and nonproblem samples (e.g., the source of the
complaint may be isolated)
• Compare indoor and outside samples (e.g., the source of the offending chemical(s) may be outdoors)
• Compare previously taken samples in the building when there were no
complaints to those taken at the same location as previously taken in
response to complaints that have since developed (e.g., the source of the
complaint may be intermittent, associated with events or activities)
In brief, there are no regulatory limits for indoor air quality. Assessing
VOCs is complex, and interpreting the results is even more difficult. Can
the identified VOC or combination of VOCs be the cause of the complaint(s),
or are they coincidental? What furnishings or building products could emit
the identified VOCs? Is the source of the identified VOCs generalized or
Volatile Organic Compounds
161
isolated? Is the source the HVAC system or sewage gas leak? Is further
sampling indicated?
Summary
Volatile organic compounds are ubiquitous. They are outdoors in pristine
rural environments, and they are indoors in occupied environments. VOCs
in indoor air, however, are compounded by confinement and build-up of a
complex mixture of chemicals that ultimately contribute to poor outdoor air
and occupant complaints.
Total VOC screening is recommended in cases where organic chemicals
are suspected of causing odor complaints of affecting the health of the building occupants. If the total VOCs exceed a predetermined acceptable limits
(e.g., 500 µg/m3), component identification is recommended.
One size does not fit all. The best methods for identification of all possible
components in an indoor air quality study are EPA Method TO-15 and TO-17,
which are also the most expensive methods. If finances allow, the two methods performed simultaneously can be a powerful tool.
If the cause is found, source identification may require more in-depth investigation and sampling. For further information, see Chapter 13, “Product
Emissions”; Chapter 16, “HVAC Systems”; Chapter 17, “Sewage Systems and
Sewer Gases”; and Chapter 19, “Green Buildings.”
References
1. Kennedy, Eugene, PhD, and Yvonne T.G. December 1993. Evaluation of Sampling
and Analysis Methodology for the Determination of Selected Volatile Organic
Compounds in Indoor Air. (Research document) NIOSH, Cincinnati, Ohio.
2. U.S. Environmental Protection Agency. Indoor Air Pollution: An Introduction for
Health Professionals. EPA. Viewed on May 8, 2010, at http://epa.gov/iaq/pubs/
hyguide.html
3. Grote, Ardith A. Screening Applications Using Thermal Desorption Techniques.
Presented at the AIHC Exposition in Kansas City, Missouri, on May 23, 1995.
NIOSH, Cincinnati, Ohio.
4. 3M Technical Staff. 2010. 3M Technical Data Bulletin—Organic Vapor Monitor
Sampling and Analysis Guide. 3M Center, St. Paul, Minnesota, pp. 7–10.
5. Dupraz, Carol, Lisa Brosseau, et al. 1997. Odor Thresholds for Chemicals with
Established Occupational Health Standards. Fairfax, Virginia: AIHA Press, p. 20.
6. Shirley A. Ness. 1991. Air Monitoring for Toxic Exposures: An Integrated Approach.
New York: Van Nostrand Reinhold, p. 406.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
7. Fortune, A. Dec. 16, 2010. Comment. Columbia Analytical Services.
8. Fortune, A. Nov. 1, 2009. “Comparison of Sampling and Analytical Methods
for Total Volatile Organic Compounds (TVOC) in Green Buildings. Presentation
from the Florida Brownfields Conference. Columbia Analytical Services.
9. P. Pope. Jan. 4, 2011. Comments. ALS/DataChem.
10. Horton, M. PhD. February 2010. Standard Method for the Testing and Evaluation
of Volatile Organic Emissions from Indoor Sources Using Environmental Chambers.
California Department of Public Health.
9
Mold Volatile Organic Compounds
and Mold Detection
The year 2000 started with a bang in that molds took center stage in the overall
consideration of indoor air quality concerns. Yet sampling methodologies are
expensive, difficult to interpret, and require long laboratory turnaround times.
There is controversy amongst the experienced environmental professionals. One investigator condemns a building, requiring extensive remediation
with minimal sampling, while another investigator attempts to assess similar scenarios by more extensive sampling and using more tools to gather
additional information. One of these tools that is gaining in popularity is air
sampling for mold volatile organic compounds.
Some investigators choose not to perform air sampling for the physical
presence of molds in the air. Due to the lack of well‑substantiated data and
clear guidance for interpretation, many investigators simply inspect for evidence of molds. These inspections may be performed by means of visual
observations, moisture testing, or odor tracking.
The purpose of this chapter is to provide a few more tools and approaches
that the investigator may find useful under different circumstances. Some of
these techniques may prove to be indispensable to some, spirit incantations
and ghost busting to others. They are mere tools, techniques that can be very
effective if used properly.
Health Effects and Occurrences
Some researchers feel that mold volatile organic compounds (MVOCs) may
cause health problems. Whereas the scientists tend to focus on sensory irritation similar to that of volatile organic compounds (VOCs), nonresearch
investigators report a concern that the MVOC may cause headaches, eye and
respiratory tract irritation, and dizziness. Currently, there is no substantiated data that correlates MVOC exposure levels to speculated health effects.
Metabolic by‑products of molds are referred to as MVOCs and consist predominantly of alkanes, alcohols, and ketones. The specific compounds that
have been identified are dependent upon mold type (i.e., genus and species),
food consumed, and environmental factors (e.g., moisture availability). At the
present, researchers are scrambling to identify MVOCs common to all fungi
163
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Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 9.1
Listing of Mold Volatile Organic Compounds2–7
Compounds
1-Octen-3-ol2,4–7
2-Methyl-1-butanol3,4,7
2-Methyl-2-butanol6,7
2-Methyl-1-propanol3,4
2-Octen-1-ol4,5,6
2-Pentanol4–7
3-Methyl-1-butanol3,6, 7
3-Methyl-2-butanol4–7
3-Methylfuran3–7
3-Octanol2,4,5,6
3-Octanone2,5–7
1-Butanol4
Dimethyl sulfide3,4
Geosmin (terpene)3,4,5,7
2-Heptanone4-7
2-Hexanone4-7
2-methyl-isoborneol5,6
2-isopropyl-3-methoxypyrazine5-7
1-Octanol7
1-Pentanol7
2-Pentylfuran7
Furan7
2-Butanone7
3-Methylfuran7
2-Ethyl-1-hexanol7
Characteristic Odor
musty, mushroom-like
weedy
nutty
sweet ester, metallic-like
earthy
and to determine variances between genera and species. See Table 9.1 for a list
of some of the more consistently reported organics that may be anticipated
wherever molds are encountered indoors. According to one laboratory that has
performed more than 600 analyses for various clients, the most frequently identified mold by‑products are 3-methyl‑l‑butanol, 2‑octen‑l‑ol, and 2‑heptanone.1
Some researchers feel that MVOC sampling data may result in more reliable mold information than viable air sampling. They state that in visually
moldy interior environments, air sampling sometimes yields false negatives.
These false negatives are often confirmed false where molds are found hidden in the wall cavities, under sheet vinyl, and within hidden spaces (e.g.,
behind sinks and cabinets). The hidden molds can be detected by odor and
confirmed by MVOC sampling.
It is unclear as to whether the MVOCs are clearly causing health problems or whether the presence of MVOCs is merely an indicator. There have
been no studies published that link the chemicals identified as MVOCs at the
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Mold Volatile Organic Compounds and Mold Detection
reported levels to be associated with health complaints. Reported levels have
been around 50.5 µg/m3 total MVOCs, 16.1 µg/m3 2‑octen‑l‑ol, and 1.8 µg/m3
methylfuran. There are no American Conference of Governmental Industrial
Hygienists (ACGIH) limits for either 2‑octenol or methylfuran, and they are
considered slightly toxic and moderately toxic, respectively.8 The other compounds listed as MVOCs are slightly to moderately toxic.
On the other hand, however, investigators have used MVOC sampling not
only to locate but to rule out the presence of molds in wall spaces. In one case,
a consultant recommended an entire residence be leveled to the ground. This
was based on known water damage, some visible molds, and minimal sampling. Another consultant investigated, drilled a small hole in each wall, took
multiple samples, and isolated the problem area to a couple of walls. The end
result was remediation of a couple of walls and some wall sections. The occupants returned to the residence, and their health complaints did not recur.
Researchers are attempting to determine the efficacy of identifying mold
genus and species by MVOC fingerprinting. Although there has been some
consistency in results with distinct differences between species, most research
has been performed under controlled laboratory conditions with well‑defined
nutrient agars. Within the same species (e.g., Penicillium varotii), many of the
MVOCs grown on malt extract agar are different from those grown on dichloran glycerol agar. In a building, the nutrients are variable. There are likely to
be more than one type of mold contributing to the total indoor MVOC, and
MVOCs that are detectable are typically lower than indoor background VOCs.
Whereas the indoor VOCs associated with off‑gassing of building materials
and furnishings may range from 200 ppb to 2 ppm, high levels of total MVOCs
may range from 0.01 µg/m3 to 2000 µg/m3, averaging around 33 µg/m3 (i.e.,
8 ppb as compared with hexanone). For MVOC findings from composites
reported at a NIOSH conference in 1997, see Table 9.2.
TABLE 9.2
Microbial Volatile Organic Compound Database10
Location/Types
of MVOC
Indoor air samples
Total MVOC
1-Octen-3-of
2-Octen-1-of
3-Methylfuran
Outdoor air samples
Total MVOC
1-Octen-3-of
2-Octen-l-of
3-Methylfuran
Average
Concentration
(11µg/M3)
# of Positive
Sites of Total
Sites Sampled
50.5
4.8
16.1
1.8
106 of 119
40 of 119
58 of 119
4 of 119
6.5
1.5
3
–
8 of 20
2 of 20
3 of 20
0 of 20
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Indoor Air Quality: The Latest Sampling of Analytical Methods
To further complicate matters, bacteria produce VOCs as well. There
has been limited research regarding bacterial VOCs, yet bacteria can contribute to the MVOCs or be the primary contributor. Bacterial VOCs may
potentially muddy the waters when interpreting these common VOCs with
the assumption that they are clearly mold by‑products. The predominant
by‑products produced by both bacteria and molds are 1‑propanol, 2‑butanol,
and dimethyl trisulfide.11 It should also be noted that actinomycetes (e.g.,
3‑methyl‑l‑butanol, dimethyl trisulfide, and geosmin), algae, and trees (e.g.,
terpenes) may produce similar VOCs as well.11,12
Sampling for MVOCs
Sampling for MVOCs is an evolving science. There is little or no published
guidance available from government sources, and there are varying opinions
amongst laboratories. The information provided herein is the most recent
information available prior to publication of this book. Locate a laboratory
and discuss their experience and capabilities for analyzing MVOCs. The protocols will remain in flux until NIOSH or another government entity publish
their own method.
Sampling Strategy
Careful consideration should be given to where sample data will provide
data that the investigator can best interpret. Exposure sampling may be
performed in order to determine exposure levels and assess the MVOC
impact on occupant health. These samples should be taken within occupied areas.
Diagnostic sampling may be performed in order to locate areas in wall
spaces where destructive sampling is not desired, and the investigator is
attempting to locate where molds are actively growing. These samples should
be taken within the wall space(s) or other inaccessible areas.
Once the decision has been made as to whether to sample for occupant
exposures or wall spaces, the investigator may wish to target sites that are
likely to represent worst case scenarios. This may be done through odor
tracking, comments from building occupants, or low‑level VOC detection
instrumentation (e.g., ppbRAE). The latter approach shows promise as a
means for tracking MVOCs to the source. The author’s experience has been
that of tracking molds using a ppbRAE like a tracking device. As the site
where molds are growing is approached, the readings on the meter become
elevated. Where background has typically been less than 300 ppb, VOC levels at identified moldy areas may exceed 1000 ppb, sometimes going as high
as 20,000 ppb (or 20 ppm).
Mold Volatile Organic Compounds and Mold Detection
167
Comparative samples should also be taken with a minimum of one
outside sample. If possible, an indoor noncomplaint or nonproblem area
should be sampled as well when performing occupied space sampling.
This is particularly important where there are no guidelines for interpreting results.
Sampling Methodology
Air sampling for MVOCs has been and can be performed by the same meth­
odologies as those used for VOC. More recently, however, specific mold
organic by‑products have been targeted, and an MVOC method developed for
those organics that have been commonly encountered in various studies.
Although the specific MVOCs that are targeted may very by laboratory, the
end result is exclusioin of the VOCs associated only with building materials,
FIGURE 9.1
Non-penetrating Moisture Meter (left) and Penetrating Moisture Meter (right)
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Indoor Air Quality: The Latest Sampling of Analytical Methods
furnishings, and activities. Otherwise, you may not “see the forest through
the trees.” The MVOC target compound sampling technique is more focused
than the broad VOC methods and easier to interpret.
The method requires the following:5,13
• Air sampling pump—low flow
• Capture medium: SKC Anasorb® 747 or comparable solid sorbent
(e.g., AS002)
• Warning: solid sorbent sampling media may be compromised by
high concentrations of ammonia, mineral acids, and high humidity
(e.g., greater than 90% RH)
• Flow rate: 0.5–0.2 liters per minute
• Range air volume: 40–120 liters
• Desorbtion: dichloromethane
• Standard: target compounds
• Analysis: GC-MS
• Limit of detection (per compound): 0.1–0.5 μg/L mL injected
dichlormethane
• Special handling: laboratory dependent (some require refrigeration and
shipping in a cooler with Coolpak while specify “do not refrigerate”)
Samples may be taken from the occupied air within a building or from
within a wall space/area suspect of having MVOCs.
Screening Methodologies
A building inspection for molds is one of many diagnostic tools that may
be used for assessing a building for potential mold growth. They go outside
“sampling” envelope and enter into other disciplines (e.g., building construction technology). At the same time, these techniques support each other and
are most effectively simultaneously. The investigator should be open to all
possibilities.
Visual Observations
As discussed in previous chapters, molds have known, predictable habits
and habitats. They thrive in high moisture. They require organic material for
nutrition, and they do not require light.
Most molds require in excess of 80 percent moisture on or in a food sub­
strate. See Tables 5.3 and 5.4 for moisture requirements of some molds. In
Mold Volatile Organic Compounds and Mold Detection
169
buildings, the food substrate may include but is not be limited to wet gypsum board paper, damp carpeting, wet wood flooring and trim, damp upholstery, moist areas under vinyl wallpaper and floor tiles, wet ceiling tiles, and
evaporation in duct insulation.
Moisture may be due to a plumbing pipe/fixture leak, sewage leak, building structural leaks (i.e., window jams, doors, and roofs), moisture buildup
from uncured concrete foundation, moisture infusion due to temperature
differentials in a building, and condensation in the air handling system.
Plumbing leaks are the easiest, most commonly identified source of
moisture buildup. The most common areas are under kitchen and bathroom sinks, and in and behind cabinets. The more difficult plumbing leaks
to detect are those around bathtubs and toilets. Second story leaks tend
to show wherein water stains become evident or water comes out from
around wall penetrations (e.g., air supply louvers and lights). Even more
difficult to locate are damaged pipes in wall spaces. Moisture buildup
inside a wall that has vinyl wallpaper can be difficult to locate as well. Yet
the glue for most wallpaper is water‑soluble, and moisture buildup will
loosen surface adhesion, making the wallpaper easy to lift. If there is no
wallpaper, a water spot may or may not appear, depending on the extent
of the leak.
Water and sewage leaks may occur around toilets or kitchen disposal units
or a cracked concrete slab. Foundation shifts provide a conduit for broken
sewage pipe moisture and gases to return to the interior air spaces.
Improperly sealed door and window jambs are typically a means whereby
moisture may enter the indoor air spaces, particularly where there is considerable moisture (e.g., excessive rain). Extreme temperature differences
between the indoor air and outside air (or indoor air and ground) may result
in moisture intrusion.
Roof leaks are a common source of moisture intrusion as well. These are
a little more difficult to track. Even if there are water stains on a ceiling,
the actual site of a leak may not be easily traced due to extensive migration
within the roof space(s).
Concrete foundations require 28 days to cure, but many contractors do not
allow more than a couple days for curing. Moisture is created in the curing process, and when resilient floor tiles or vinyl sheeting are laid over the
uncured surface, moisture becomes trapped and accumulates. It should also
be noted that the old asbestos floor tiles permitted moisture to escape, and
the tiles were typically laid down with a solvent‑based glue. The nonasbestos tiles trap the moisture, and these tiles are typically laid down with a
water‑based glue. When the water‑based glues get wet, the glue begins to
fail and the tiles begin to lift. Commercial carpeting may also have been put
down with water‑based glues. Thus poor adhesion of floor surface materials
is a good indicator of potential moisture buildup.
Condensation in a commercial air handling system and window air conditioners occurs at the cooling coils. In large commercial units, the condensate
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Indoor Air Quality: The Latest Sampling of Analytical Methods
is collected in a drip pan where it should drain out of the unit. Often the
unit fails to drain the full amount of settled water. Sometimes the drain gets
plugged. This condensate buildup in the drip pan is a frequent source of
moisture for molds to grow. Yet it does not stop here.
The moisture from the coils and drip pan is blown onto the surface
immediately after the cooling coils. This surface may or may not be insulated. The author has observed molds growing on what would otherwise
appear to be a clean metal surface. More frequently, however, this area
immediately after the cooling coils is covered with impregnated fiberglass
insulation. A feltlike surface covering may be observed that may later be
confirmed as mold.
Poorly insulated duct or noninsulated spots in walls may also be a source for
condensation buildup, especially where the temperature difference is extreme
between the air in the ducting and outside in an attic space. The condition
of the duct and insulation may be observed, and moisture buildup can be
observed. Sometimes condensation occurs at the air supply registers. Molds
may be observed growing on the outer edge of the louvers or just inside.
The nutritional source may be glue, paper, decayed organic matter, organic
debris, soil, and human food. Many of these materials are found in house
dust that can be found in all areas mentioned above.
Odor Tracking
Odor thresholds for some of those by‑products produced by molds are quite
low. For instance, the odor threshold for dimethyl trisulfide has been reported
as low as 10 ppt. For 1,5‑octadien‑3‑ol, the threshold has been published as
low as 1 ppt, and geosmin is noticed at 5 ppt.14,15 For comparison, the very
distinct odor for hydrogen sulfide is noticeable for many at 4.5 ppb, and for
a limited number of people, the rotten egg odor is sometimes identified at
levels as low as 70 ppt.
Note that there are no ACGIH or Environmental Protection Agency (EPA)
standards for dimethyl trisulfide, 1,5‑octadien3‑ol, or geosmin, whereas the
ACGIH TLV‑TWA for hydrogen sulfide is 5 ppm. Thus in the case of MVOCs,
odor should not be mistaken as an indication of excessively high levels of
MVOCs or health effects.
To overstate the obvious, some people have a greater sense of smell than
others. Those of such great fortune (or misfortune) who are able to track
odors may go to the source. Sometimes building occupants can direct the
investigator to a source.
Odors are typically associated with visually observed molds out in clear
view, but sometimes odors can be isolated and molds located behind or in
hidden spaces. These hidden spaces may include but are not be limited to
wall spaces (e.g., behind light sockets), around windows, areas under carpeting, behind bathroom sinks, and ceiling spaces.
Mold Volatile Organic Compounds and Mold Detection
171
One drawback to tracking odors is that by the time a moldy odor is
noticed, the odor has diffused into the general air space or been mixed with
the air from within the air handling unit. For this reason, if the source is the
mechanical air ducts, interpretation can be particularly difficult. Odor alone
will rarely isolate the problem. Other methods must be used.
Moisture Testing
Where moisture cannot be observed and is suspect, a moisture detector is
quite useful. Without a moisture meter, an investigator may overlook potential areas for mold growth, or suspect areas must be demolished. The later
culminates in poor aesthetics, potential release of enclosed mold spores, and
expensive repairs.
A moisture meter detects moisture through paint, varnish, wallpaper, floor
tiles, wood, and carpeting. There are two types of meters. Each is useful in
a different way. The nonpenetrating moisture meter (e.g., Tramex® Moisture
Encounter) is nondestructive, and the penetrating meter (e.g., Delmhorst
BD-21) has prongs that must penetrate in to the substrate leaving small holes
where the substrate was tested.
It should be noted that metal will also defect the meter. If the material
being tested has metal composition or structural steel behind the surface, the
meter will read high moisture content. Some gypsum board has an aluminum foil backing to provide thermal insulation where the gypsum board is
used along exterior walls. The aluminum foil will deflect the meter full‑scale,
result in erroneous readings regarding moisture content.
The non-penetrating moisture meter has three scales that are based on
depth of reading and sensitivity, and it has two ranges. The relative range is
that used most frequently, and the percent wood range is for wood only.
• Scale 1, the wood setting, is used to measure from the surface down ½
to ¾ inch deep, and the reading is in percent water. Dry wood should
read less than 12 percent on the % H2O Wood indicator range. Do
not expect treated lumber to be dry. The treatment process is a wet
process and prevents fungal growth.
• Scale 2, the drywall setting, is used to measure from the surface
down to 1 inch deep, and readings are in relative moisture content. At the setting, the meter may be used to penetrate carpeting,
floor tiles, and roofing shingles. Scale 2 may be used to encounter
moisture in a second layer of drywall. A fire wall will generally
have two layers of drywall. It may be used to encounter moisture
trapped below floor tiles. If there is wood flooring, Scale 2 can penetrate the surface sufficiently to determine moisture that lies beneath
the wood.
• Scale 3, the plaster/brick setting, measures from the surface down
¼ to ½ inch deep, and readings are in relative moisture content. Yet
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Scale 3 may be used to check depth of moisture the drywall. If there
is little or no reading at ¼ to ½ inch depth, a reading on Scale 2
is likely to indicate most of the moisture is deeper. If, however, the
Scale 3 reading is higher than the Scale 2 reading, the moisture is
likely to be closer to or on the surface. For instance, moisture may
be trapped behind vinyl wallpaper or there may be condensation on
the surface.
A penetrating moisture meter is slightly more complicated. One cannot compare penetrating meter reading to nonpenetrating readings. This would be like
trying to compare apples to chocolate. Both are good, but they are different!
The penetrating moisture meter reading resistance between two probes
that must penetrate the surface of the substrate to get a reading, and the
meter only provide moisture content information between the two probes.
Most penetrating moisture meters come with ¼ inch probes. This means that
if there is moisture at a depth greater than ¼ inch, there will be little or no
reading. Yet there is a way around this minor problem. Extension probes up
to 3 inches in length can be attached to the meter, extending the measuring depth considerably. Well, now, we have another problem. The surface of
most materials (unless drywall is overly wet) is too hard to penetrate without
predrilling a couple holes. Whereas the smaller probe leaves small holes, the
larger probe generally leaves unsightly ¼ inch holes.
There are also three scales for the penetrating moisture meter, and all the
readings are in moisture content, not relative moisture.
• Scale 1, the wood setting, is similar to that of the nonpenetrating
moisture meter. In both, red line and buzzer indicate percent moisture content in excess of 17. The probe, once again, only reads as deep
as the probe will go, whereas the nonpenetrating goes down as far as
¾ inch.
• Scale 2, the plaster/concrete setting, will red line and buzz at 95 percent moisture content. The red line for plaster on the nonpenetrating
is 70 percent relative moisture.
• Scale 3, the drywall setting, will red line and buzz when its reading
is greater than 1 percent moisture content. The red line for drywall
on the nonpenetrating is 70 percent relative moisture.
The nonpenetrating moisture meter is easier to use and does not turn the
wall into a pin cushion. A penetrating meter can be used to test the surface
of a substrate without penetrating. Given this approach, the investigator can
determine whether there is surface moisture. Otherwise, when the depth of
the moisture is required or where a depth greater than 1 inch is required, the
penetrating meter shines. Both tools used wisely can provide information
that would otherwise be incomplete.
Mold Volatile Organic Compounds and Mold Detection
173
Interpretation of Results
When assessing occupied space MVOCs, indoor sample results should be
compared to outside samples. Short of concluding that the results outside are
a given multiple of that indoors, identified MVOCs that have exposure limits may be compared wit other standards in a similar fashion to that of that
of VOCs. It is highly unlikely, however, that any known standards will be
exceeded. Otherwise, the investigator should seek the assistance of someone
with more experience, expertise.
One laboratory that has considerable experience with MVOC analysis has
published interpretation tables. If a comparison outdoor has not been taken,
the laboratory suggests adding all the identified MVOC results and refer to
a table which is based on “experience gained . . . through interactions with
many professionals who are active in mold sampling and remediation.” See
Table 9.3.
When assessing wall space MVOCs, in-wall sample results should be compared to outside samples and possibly samples obtained from wall spaces
known not to have or to be associated with mold growth. Sample results
will, once again, be relative to known non-problem areas. In this instance,
interpretive tables are not likely to be appropriate. Comparison samples are
a must!
Positive findings upon the visual observation of what appears to be mold
should be confirmed. That which appears to be mold is not always mold. For
instance, one building owner was prepared to close down a restaurant and
spend large sums of money on remediating a black velvet-looking spot in
the kitchen area. Confirmatory sampling disclosed that the mold was indeed
grease with carbon particles from cooking.
TABLE 9.3
MVOC Interpretation in Occupied Indoor Spaces (Where No Outdoor Comparison
Samples Were Taken)
Sum (ng/L)
Level
Explanation
<8
Minimal
30–Aug
Low
30–150
Moderate
140–300
Heavy
>300
Severe
Actively growing molds may be present but are at or below
levels found in most homes of working environments.
Actively growing molds are present but at levels which,
generally, may only affect people very sensitive to molds.
Actively growing molds are present, significant allegic
reactions are possible.
Very significant levels of actively growing molds are present,
significant allergic reactions are very probable.
Very high levels of actively growing molds are present,
immediate action should be taken.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
On the other hand, negative visual observations do not necessarily mean
there are no molds. Moldy, earthy, musty odors may be traced to enclosed,
hidden areas, and a moisture meter may identify high moisture areas. Both
scenarious are likely to be associated with molds. In these cases, further
investigation by demolition, surface sampling, and/or mold air sampling is
indicated.
Even when MVOC sampling and a building inspection fail to identify any
observable molds or molds that can be found through demolition, air sampling may still indicate a problem. Then, the onus comes back to the inspector. The search is afoot!
Summary
MVOC sampling and building inspections have been added to the investigator’s bag of tricks. MVOC sampling is best utilized to locate mold growth in
hidden spaces. Visual observations can be very effective in identifying probable
sources of mold growth, and the more knowledge an investigator has regarding
building construction technology, the more effective a building investigation.
Characteristic mold odors and MVOCs may be traced to a source or site(s)
where there is potential mold growth. A moisture meter may be used to
locate moisture, growth havens for molds. The combined approach for identifying growth sites can be highly effective. Yet a visual inspection of suspect
areas may be required for confirmation.
References
1. Air Quality Services. Using Microbial Volatile Organic Compound Analysis to
Detect Mold in Buildings. AirfAQS Extra. 5(3).
2. Burge, H.A. Bioaerosols. CRC Press, Boca Raton, Florida. (1995), p. 258.
3. Sunesson, A.‑L., et al. Identification of Volatile Metabolites from Five Fungal
Species Cultivated on Two Media. Applied and Environmental Microbiol­ogy.
61(8):2911–18 (1995).
4. Wessen, B., and K. Schoeps. Microbial Volatile Organic Compounds—What
Substances Can Be Found in Sick Buildings? Analyst. 121:1203–05 (1996).
5. ACGIH. Bioaerosols: Assessment and Control. ACGIH, Cincinnati, Ohio (1999).
pp. 26–1.
6. Aerotech Labs. IAQ Tech Tip #42: MVOCs. http://www.aerotechlabs.com
(October 2000).
7. PATI. MoldScan.TM Application Note 523 rev. 1. Prism Analytical Technologies,
Inc., Mt. Pleasant, Michigan. (2010).
Mold Volatile Organic Compounds and Mold Detection
175
8. Lewis, R.J. Sax’s Dangerous Properties of Industrial Materials, 10th ed. John Wiley
& Sons, Inc. New York (2000).
9. Air Quality Services. Using Microbial Volatile Organic Compound Analysis to
Detect Mold in Buildings. AirfAQS Extra. 5(3).
10. Moray, P., A. Worthan, et al. Microbial VOCs in Moisture Damaged Buildings.
Healthy Buildings lIAQ 97. Conference Venue. Natcher Conference Center at
National Institutes of Health, Bethesda, Maryland. 1:247 (September 27–October
2, 1997).
11. Burge, H.A. Bioaerosols. CRC Press, Boca Raton, Florida (1995), p. 260.
12. Ibid., pp. 250, 258.
13. PATI. Instructions for Jaking in Samples Using As002 Tubes. Technical Bulletin
502 rev. 9. Prism Analytical Technologies, Inc., Mt. Pleasant, Michigan. (2010).
14. Ibid., p. 251.
15. Pengfei, G. MVOCs. E‑mail from Centers for Disease Control (September 28,
2000).
16. PATI. How to interpret MoldScan results. Technical Bulletin 525 Rev 2. Prism
Analytical Technologies, Inc., Mt. Pleasant, Michigan. (2010).
10
Carbon Dioxide
An angry complaint is lodged, “There is no oxygen in the room. Everyone
is passing out!” The comment comes from an office occupant in a building
where this health complaint is unique. The occupant had previously complained about the cold air supplied in her office space. Subsequently, her air
supply was turned off, and when accommodating visitors, she closed the
door to her already stuffy office. The predictable results were elevated levels
of carbon dioxide in a confined space.
Ever-present in our outdoor environment, carbon dioxide levels are normally higher indoors than outside. The elevated levels indoors may be due to
combustion, leaking compressed gases, and animal respiratory by-products.
In indoor air quality, carbon dioxide is primarily an indicator gas. It is an
indicator of inadequate fresh air or insufficient dilution of air contaminants
generated in a building.
The source of complaints may be formaldehyde off-gassing from furniture,
but the elevated levels of formaldehyde may be alleviated with an increase in
fresh air entering the building. The carbon dioxide levels provide information as to the adequacy of fresh air supplied to the occupied spaces. This is
the first consideration in rectifying an indoor air quality concern.
Occasionally, however, carbon dioxide contributes to health complaints in
a subtle fashion. In some cases, indoor air quality investigations have been
associated elevated carbon dioxide levels with complaints of stuffiness and
inadequate air. The sense of inadequate fresh air may be voiced in terms of
“can’t breathe” or a “stuffy, suffocating sensation.”
Rarely are the carbon dioxide levels excessive to the point of causing a significant impact on human health. At levels well in excess of those normally
found in indoor air quality studies, carbon dioxide is a simple asphyxiant.
When levels approach percent of total air, carbon dioxide begins to displace
the much-needed oxygen. The most sensitive sign of reduced oxygen in the
breathing air is a reduced ability to detect slight differences in the brightness
of objects. As the levels increase, the symptoms progress from an increase
in heart or respiratory rate to headache and a feeling of fatigue. In extreme
intoxication, exposed individuals may experience nausea and vomiting, progressing to collapse and unconsciousness.
As an indicator, carbon dioxide levels are used predominantly to determine adequacy of the air exchange and to isolate stagnant air pockets where
there is little or no air movement. Although the air exchange in an office
building may be adequate, areas may not receive their share of supplied air.
177
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Indoor Air Quality: The Latest Sampling of Analytical Methods
For those rare occasions whereby carbon dioxide levels may become excessive, the investigator should be aware of the potential sources. The assessment of carbon dioxide levels is a basic tool to be utilized in all indoor air
quality investigations.
Occurrence of Carbon Dioxide
Carbon dioxide is a colorless, odorless gas. When mixed with water, it is
referred to as carbonic acid that has a slightly acid taste.
Humans and other animals inhale oxygen and expel carbon dioxide as a
waste product. Plants inhale carbon dioxide and expel oxygen. According
Charles Keeling, ambient carbon dioxide levels shift hourly, daily, and
annually. In the afternoon, levels have been recorded as low as 0.031 percent
(i.e., 310 ppm). Annual measurements taken at Mauna Loa Observatory in
Hawaii (the site of a volcano that erupted as recently as 1984) have recently
been recorded, on the island, at 0.0385 percent (i.e., 385 ppm). There are
slight variations in these levels, depending on location (e.g., rural farmland),
the time of year (e.g., plant uptake of carbon dioxide occurs during growing
season in the summer), weather (e.g., air inversions may trap and result in
an increase of all air pollutants), and industrial exhaust (e.g., combustion
by-products).
In indoor air quality, the primary source of carbon dioxide is human
expelled air. The expelled air builds up in airtight buildings, confined air
spaces (e.g., enclosed offices with no air supply), overcrowded spaces (e.g.,
classrooms), and high activity areas (e.g., health clubs). Thus indoor carbon
dioxide levels are usually greater inside a building than outside, even in
buildings with no health complaints.
Typically, at the start of an office day, the carbon dioxide levels will be
around that of outside air (e.g., 400 ppm). As the occupancy increases with
time, so do the carbon dioxide levels. The levels increase and decrease
with the fluctuations in occupancy. In an office building, the peak carbon
dioxide levels tend to occur in mid-afternoon at about 1000 ppm. Where
there is adequate outside fresh air exchange, the peak may be as low as
800 ppm. Where it is inadequate or nonexistent, the levels may exceed
1000 ppm.
Other sources of carbon dioxide are by-products of combustion (e.g., automotive traffic), sugar fermentation, ammonia production, carbonated beverages,
compressed carbon dioxide (e.g., fire extinguishers), dry ice, and aerosol propellants. Common indoor sources may also be gas cooking appliances, space heaters, wood-burning appliances, and tobacco smoke. Industrial exhausts whereby
burning is involved (e.g., sanitary waste) should not be ruled out. All potential
outside contributors to the total carbon dioxide levels should be investigated.
Carbon Dioxide
179
Outside the building contributors to the total indoor carbon dioxide levels should
be assessed—at the HVAC air intake for the building or other areas where the
outside air might conceivably enter the building (e.g., frequently used doors and
carbon dioxide in the proximity of the doors).
A carbon dioxide level in excess of 1000 ppm should be considered an indicator of inadequate makeup air in a building. The recommended limit to minimize health effects according to the American Conference of Governmental
Industrial Hygienists (ACGIH) is 5000 ppm.
Sampling Strategy
In offices and conditioned school buildings, the investigator should perform
air monitoring for carbon dioxide to assess the adequacy of the makeup air.
As carbon dioxide levels change over time with occupancy rates, the investigator needs to be aware of the time of day when samples are collected. In
areas where the occupancy and activities are not consistent, the carbon dioxide levels will fluctuate accordingly.
Consider the conditions, and determine sample locations accordingly. Con­
ditions to be considered should include, but not be limited to, the following:
•
•
•
•
•
•
•
•
•
Different air handling zones
Worst case complaint areas
Noncomplaint areas
Heavily occupied areas during peak occupancy periods
Enclosed office spaces (air supply open or close)
Center of cubicle areas
Occupied and nonoccupied spaces
Different activity areas
Time of day and occupancy
In areas where the occupancy and activities are not consistent, the carbon
dioxide levels will fluctuate. In an ideal world, the investigator should take
three samples at each location. These samples should be taken at occupancy startup, mid-day, and mid-afternoon (e.g., 9 a.m., 12 p.m., and 3 p.m.).
Wherever feasible, a data logging monitor may alternatively be placed in one
or two of the more strategic locations for 8- or 24-hour monitoring.
In some instances, the investigator may not have the benefit of an all-day
evaluation. If limited in time, attempt to assess areas around times when levels would reasonably be expected to be at their highest (e.g., mid-afternoon
in an office building).
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Indoor Air Quality: The Latest Sampling of Analytical Methods
The investigator may choose to take numerous samples and contour an
area. This can be informative while providing an easy to review visual of
recorded numbers and relative references. The number of samples collected,
however, may be limited by sampling methodology.
Sampling Methodologies
Air sampling may be performed by direct reading instrument, colorimetric detector reading, or evacuated air collection. Whereas a direct reading
instrument and colorimetric detection provide instantaneous data, collecting a sample requires laboratory analysis. The approach to each of these
methods is discussed herein.
Direct Reading Instrumentation
If a large number of data points are required and the equipment is readily
available, direct reading instrumentation is the most feasible approach to
carbon dioxide monitoring. Equipment may be purchased or rented.
Carbon dioxide monitoring will generally be part of an indoor air quality monitor that provides continuous real-time data on four parameters—
temperature, relative humidity, carbon monoxide, and carbon dioxide.
Many of these instruments also record and store the parameters. They
allow for long-term monitoring in order to track changes in carbon dioxide levels throughout the day or even for a 24-hour time period. See
Figure 10.1.
Colorimetric Detectors
If a small number of data points are to be collected and direct reading equipment is not readily available, colorimetric detection is the most feasible
approach. The initial purchase of a pump and detector tubes is relatively low
in cost, and equipment is easy to carry. However, when the sample numbers
exceed 10, the cost of the tubes starts to outweigh the cost of direct reading
equipment rental.
The term “detector” is an operative term in that colorimetric detectors
detect levels instead of providing precise data. Yet they are simple, easy to
use, and practical for spot checks and collecting limited samples when direct
reading instrumentation is not available.
Colorimetric detection of chemicals is vintage science that has been available for more than 50 years. Detection is based on a chemical reaction between
the specially prepared sample tube and the gas or vapor.
Carbon Dioxide
181
FIGURE 10.1
Indoor air quality monitor—KD AirBoxx Monitor (Courtesy of KD Engineering in Bellingham,
Washington).
Sampling equipment includes a hand held bellows or piston pump and detector tubes, specific for the chemical in question (e.g., carbon dioxide). The pump
and tubes must be from the same manufacturer. Do not mix products (e.g., a
Drager tube with an MSA pump). The tubes are chemical specific with different
ranges (e.g., 0.01 percent to 0.3 percent by volume, which is 100 to 3000 ppm).
The detection methods have a manufacturer rated accuracy of 15 percent to
25 percent, depending on the manufacturer. Some experienced investigators,
however, have found variances in the low range that depart from direct reading
instrument data taken at the same location by as much as 50 percent.
When the components within the tube react with the gas or vapor being
sampled, there is a color change (e.g., white to violet). The tube is marked with
generalized detection levels, and the length of the color change provides information regarding the detection level at that point in time. See Figure 10.2.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 10.2
Drager colorimetric detector kit with carbon dioxide sample tubes.
Determine potential interferences or cross-sensitivities. There are no crosssensitivities listed for Drager® carbon dioxide detector tubes.
The sampling method is summarized as follows:
• Equipment: bellows or piston pump
• Sampling medium: carbon dioxide detector tubes in desired range
• Procedure: insert tube in pump holder with arrow pointing toward
the pump, squeeze and release the pump for the number of strokes
designed by the manufacturer (1 to 10 times), allowing the pump
bellows or piston to fill completely between each stroke
• Analysis: read the concentration on the basis of the perceived length
of the color change
Helpful Hints
Take prolific notes, and record sample locations on a building schematic. The
best reference is a visual of instantaneous or long-term averaged data. If it is
not possible to record the sample locations on a schematic, record the precise
sample location and rationale for sampling at that location (e.g., no air movement). Always record the time each data point was collected.
Carbon Dioxide
183
Don’t hold or place the monitoring probe or sample inlet close to your face.
Breathing into the monitor will result in unreasonably elevated data. The
placement of a monitor for long-term data logging should also be so placed
as to avoid other people from breathing directly into the monitor probe.
Upon final analysis, however, a well-planned sample site may culminate in a
few surprises (e.g., a small mid-day meeting of people around the vicinity of
the monitor). Attempt to keep track of activities, and never assume an unattended monitor will remain untouched.
Interpretation of Results
Properly ventilated buildings should have carbon dioxide levels between 600
and 1000 ppm with a floor or building average of 800 ppm or less.1 The 1000
ppm should be used as a guideline only. It is not a strict, not to be exceeded
limit. It is only a guide or indicator to adequate fresh air.
Assess the results in terms of occupancy, location, and time of day. One
area may exceed 1200 ppm while other areas average below 800 ppm. There
is a reason for this discrepancy. It deserves further investigation. Do not
damn the entire building for the sins of one area! The cause of a single discrepancy may be insufficient or no air supply to an area, or it may be due to
unusually high traffic on the day of the monitoring (e.g., large meeting in a
small conference room).
If all areas average above 1000 ppm, however, and the outside air is less
than 400 ppm, the environmental professional should suspect insufficient
outside air. Insufficient outside air means the indoor air contaminants are
likely to be entrained within the HVAC system. Product/building material
emissions and other building activity contaminants will build up over time
and contribute to poor indoor air quality. Thus elevated carbon dioxide levels may serve as an indicator or early warning sign of contaminant buildup
within the occupied area(s).
On the other hand, if the carbon dioxide levels are extreme and the makeup
air supplied to the building is open (and confirmed to be adequately open),
contaminant buildup may be a red herring. The source of the problem may
be outdoors.
Where the levels exceed the ACGIH recommended limit of 5000 ppm
and the outside air is less than 400 ppm, seek other sources besides human
exhaled carbon dioxide inside the building. It may be coming from byproducts of combustion from within, and they may yet to be identified.
Otherwise, exceeding the limit of 5000 ppm is likely to be associated with
outside sources (e.g., industrial exhausts).
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Summary
Carbon dioxide monitoring is primarily a diagnostic approach for determining the adequacy of the fresh air supplied to a building or occupied space.
The source of elevated carbon dioxide levels is generally, but not always, a
normal human by-product. Other sources are possible, and limits are not
precisely defined. Be open to all possibilities!
11
Carbon Monoxide
According to the American Medical Association, 1500 people die annually
due to accidental carbon monoxide exposures. More than 10,000 people seek
medical attention, and there are infinitely more who experience the nonlethal
health effects and fail to report their mishaps. Medical experts speculated
the reason for underreporting is that the symptoms of carbon monoxide poisoning resemble other common ailments and are not recognized as carbon
monoxide poisoning.
Carbon monoxide displaces oxygen in the oxygen-to-blood transfer in the
lungs. It has an affinity for the oxygen‑carrying sites on the hemoglobin in
the blood of 210 to 240 times greater than oxygen. As it displaces the oxygen,
carbon monoxide prevents the distribution of the needed oxygen. The tissues
become oxygen starved, and the individual fails to receive adequate oxygen
supply. The higher the carbon monoxide levels, the greater displacement of
oxygen occurs, and the more oxygen deficient the individual becomes.
Initial symptoms may be mistaken for the common flu or a cold. This
includes shortness of breath on mild exertion, mild headaches, listlessness,
and nausea. As exposures increase, the individual may experience severe
headaches, mental confusion, dizziness, nausea, rapid breathing, and fainting on mild exertion. In extreme cases, not normally encountered in indoor
air quality situations, exposures may result in unconsciousness and death.1
In indoor air quality, the initial symptoms of carbon monoxide poisoning
may be difficult to differentiate from other causes of health complaints. After
determining the occupants have symptoms that may indicate carbon monoxide poisoning, the investigator should be prepared to identify potential
sources and perform air monitoring.
Occurrence of Carbon Monoxide
Carbon monoxide is a colorless, odorless gas. It is a flammable, combustion
by‑product, an important contributor to heat production. Carbon monoxide provides more than two‑thirds the heat value created by carbon‑based,
combustible materials. In oxygen‑rich air, carbon monoxide burns to form
carbon dioxide. When there is insufficient oxygen, however, carbon monoxide does not burn completely and becomes one of the many by‑products
of combustion.
185
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Incomplete combustion by‑products of carbon‑based fuels consist of
other contaminants as well. These products often have a color (e.g., red
nitrogen dioxide gas) or an odor (e.g., aldehydes and volatile organic compounds). Although carbon monoxide is colorless and odorless, other combustion by‑products may be detected. If one complains of gasoline odors,
the presence of volatile organic compounds should set off alarm bells to
the investigator.
Combustible carbon‑based materials include wood, charcoal, coal, natural
gas, gasoline, diesel fuel, kerosene, oil, organic waste, and tobacco products.
Materials less commonly implicated in indoor air quality studies are building, automotive, furniture, interior, and decorative materials involved in
fires. Although rare, the latter scenario involving fire damage in or around
the complaint area should not be overlooked.
In most instances, sources of elevated levels of carbon monoxide and other
combustion by‑products are encountered in one, or a combination of, the following scenarios:
• Vehicle exhaust in a building (e.g., air intake to a building located at
street level in a busy alley or an automobile left running in a garage)
• Poorly vented gas‑fired hot water heaters
• Air from a leaking exhaust duct or furnace flue
• Combustion by‑products vented close to an air intake for a building
• Poorly sealed wood‑burning stoves
• An insufficient amount of oxygen supplied to a gas‑operated
space heater
• Poorly tuned forklift trucks
• Poorly vented and insufficient replacement air in a building with
natural gas and wood burning fireplaces (e.g., tight buildings with
little or no air coming from outside to replace the air discharged
through the chimney)
• Gas‑fired heaters in air handling units
• Industrial combustion gases from an associated building
Exposures may be the result of a complex mixture of multiple sources.
Individuals may be exposed at work and in their automobile that has a leaky
muffler with the exhaust entering the interior of the car. Cigarette smokers
are exposed to carbon monoxide when smoking tobacco products. Activities
outside the building or in a separate area of the same building may contribute to carbon monoxide levels in the area under investigation.
Time of exposure can be elusive! Carbon monoxide levels in the blood
hemoglobin have a three- to five‑hour half life. This means it takes up to five
hours for half of the carbon monoxide tying up the oxygen receptor sites in
Carbon Monoxide
187
the blood to dissipate. In other words, when an individual departs an area
where he/she is exposed to a carbon monoxide generating activity, the symptoms persist. For example, a carbon monoxide emitting gas heater may only
operate in the morning and not in the afternoon. The occupants develop
symptoms that persist throughout the day, beyond the time of exposure. The
environmental professional assesses the area in the afternoon only to find
low or no carbon dioxide exposure.
So, be prepared to investigate any and all possibilities wherein carbon
monoxide poisoning is suspect. A good, solid sampling strategy is a must!
Sampling Strategy
Occupants in an office space complained of severe headaches, nausea, and
chronic fatigue that persisted into the weekend. The office space is located
above industrial activities where by propane forklift trucks are operating
constantly. In the morning, diesel trucks back up to loading docks and
remain running for the duration of the loading process. The exhaust plume
from the trucks had been observed blowing toward the building eaves and
occasionally into the air intake for the office spaces.
The evidence was overwhelming that carbon monoxide was the culprit,
but air monitoring was met with resistance from the industrial teaser of the
office space. As the sampling strategy turned into an intense chess game,
the investigator should be aware that the obvious may become an unrivaled challenge.
The investigator should perform air monitoring for carbon monoxide
whenever complaints include symptoms of carbon monoxide poisoning
and a potential source has been identified. Even if an unidentified or industrial exhaust source is merely suspect, the investigator should perform air
monitoring.
When the source has been identified, one worst case sample may be taken
for diagnostic (not exposure) monitoring at the source. Do not take the sample at the breathing zone of the occupant(s) since by the time the carbon
monoxide reaches them, the level of exposure will be considerably diminished and not as easily identified. So, first, attempt to identify the worst case
scenario at the source and, second, determine the occupant(s) exposure. One
occupant exposure should be minimal.
As the time of occurrence may not be clear, ongoing monitoring should be
performed for the duration of the building occupancy. In an office building,
occupancy may occur from 7 a.m. to 6 p.m. In a residence, occupancy may
include 24 hours. In long-term sampling, if the monitoring equipment is left
unattended, the investigator should check prior to sampling to determine if
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Indoor Air Quality: The Latest Sampling of Analytical Methods
the suspect event is likely to occur and confirm the occurrence of the event
after sampling. For instance, if the suspect event is early morning diesel
truck traffic and the trucks fail to deliver on a morning when they were
scheduled, sampling should be rescheduled for a time to include truck
deliveries.
If attempting to sample in a confined air space (e.g., closed conference
room), confirm the doors remained closed during the sampling period. If
you place a “do not disturb” sign on the door and on the monitor, do not
assume compliance. Some additional measures may be needed to assure the
area is secured.
In urban environments, always take an outside background air sample for
comparison. Where the investigator monitors elevated levels indoors, outdoor air sampling should be performed. All contributing outdoor sources
should be recorded.
Sampling Methodologies
Whereas direct reading instrumentation or colorimetric detectors both provide instantaneous data, the direct reading instrumentation provides ongoing data. There are higher initial costs for instrumentation, but detector tubes
involve a low cost per sample. The desired number of samples and accessibility of equipment are important considerations to choosing the more practical
approach to air sampling.
Direct Reading Instrumentation
If a large number of data points are to be collected and equipment is readily available, direct reading instrumentation is the most feasible approach.
They are available both for purchase and for rental. For low usage and minimal maintenance situations, rental is the most practical means for accessing
equipment.
Carbon monoxide monitoring equipment may be purchased or rented
as dedicated units or part of a four‑gas monitor. Most are data logging
instruments that record time‑exposure data. Some have a recorder that
provides ongoing data that is recorded onto a strip chart while others
simply provide a digital readout of data points that the investigator must
record on paper. See Figures 11.1 and 11.2.
Colorimetric Detectors
Colorimetric detection is the most feasible approach wherever a small number of data points are to be collected and direct reading equipment is not
Carbon Monoxide
189
FIGURE 11.1
Single gas direct reading data logger—EL-USB-CO meter. (Courtesy of Lascar Electronics).
FIGURE 11.2
Multiple gas direct reading data logger with carbon monoxide sensor—MultiRAE® Toxics
Monitor measures carbon monoxide, volatile organic compounds, hydrogen sulfide, and combustibles (Courtesy of RAE Systems, San Jose, California).
readily available. For up to 10 samples, colorimetric detectors are more economical than direct reading instrumentation.
Colorimetric detection of carbon monoxide is based on a reaction with
chemicals contained within the detector tube. A color change occurs, and
the length of the discoloration (e.g., Drager® white to brownish green) is the
measure of concentration.
Sampling requires a handheld bellows or piston pump and carbon monoxide detector tubes. The pump and tubes must be made by the same manufacturer. The tubes are chemical specific with different ranges (e.g., 2 to 60 ppm
and 8 to 150 ppm).
As concentration is difficult to read, results may be off by as much as
50 percent. Although this method lacks accuracy, the range of ± 50 percent
has minimal impact.
Although there are several potential interferences or cross-sensitivities for
carbon monoxide detector tubes, they may be filtered with a carbon prefilter. The potential cross-sensitivity chemicals are petroleum hydrocarbons,
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Indoor Air Quality: The Latest Sampling of Analytical Methods
benzene, halogenated hydrocarbons, and hydrogen sulfide. For example,
halogenated hydrocarbons (e.g., trichloroethane) in high concentrations can
discolor the indicating layer to a yellowish brown.
The sampling method is summarized as follows:
• Equipment: bellows or piston pump
• Sampling media: carbon monoxide detector tubes in desired range
• Procedure: insert tube in pump holder with arrow pointing toward
the pump, squeeze and release the pump for the number of strokes
designed by the manufacturer (1 to 10 times), allowing the pump
bellows or piston to fill completely between each stroke
• Analysis: read the concentration on the basis of the perceived length
of the color change
Helpful Hints
Take prolific notes, and record sample locations on a building schematic.
There is great truth in the old adage “a picture says a thousand words.”
Record the precise sample locations and sample times, and sketch the sample location wherever possible. Also be certain to record the time each data
point was collected, conditions, and activities that may impact the interpretation of results.
Be particularly cautious whenever intending to leave data logging equipment unattended for an extended period of time. Murphy’s law may be
instituted during an abbreviated departure from the sample site, particularly where another party may benefit by altered conditions. In other words,
“Anything that can go wrong, will go wrong.” Count on it!
Interpretation of Results
Enforceable limits and nonenforceable exposure guidelines for carbon monoxide
are 9 ppm (Environmental Protection Agency, EPA), 50 ppm (Occupational
Safety and Health Administration, OSHA), 10 ppm (World Health Organization,
WHO), 35 ppm (National Institute for Occupational Safety and Health, NIOSH),
and 25 ppm (American Conference of Governmental Industrial Hygienists,
ACGIH). Whichever standard/guideline was used in the past has changed!
The Leadership in Energy and Environmental Design (LEED) and American
Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE)
189.1 “maximum concentration limit” for carbon monoxide exposures in
Carbon Monoxide
191
nonoccupatonal, indoor air quality assessments is 9 ppm or not greater than
2 ppm above background carbon monoxide levels. Background carbon monoxide levels in rural environments are typically zero, but background levels
in a city (e.g., high vehicle traffic) or around industrial environments may
exceed 9 ppm.
The LEED and ASHRAE guidelines for carbon monoxide indoors are in
line with the EPA enforceable limits for outside air with but one caveat. If
the outside air exceeds 9 ppm, the LEED and ASHRAE guidelines raise the
limit to 2 ppm above the outside carbon monoxide levels. For instance, if the
outside carbon monoxide level is 10 ppm (EPA noncompliance for 8-hour
exposures), the indoor air quality limit becomes 12 ppm.
Summary
Carbon monoxide monitoring should be performed whenever carbon monoxide poisoning is suspect and where there is a known source in or around
the complaint area. The symptoms may be elusive wherein carbon monoxide
is slightly elevated, and all sources of carbon monoxide may not be obvious.
If monitored exposures are below the 9 ppm limits and carbon monoxide
poisoning is suspect or confirmed (e.g., blood carboxyhemeglobin testing),
ask questions and perform additional sampling. Due to the extensive time
required for carbon monoxide to dissipate from hemoglobin, an investigation may prove to be very challenging. Long-term data monitoring is ideal!
Reference
1. Proctor, N.H., and J. Hughes. Chemical Hazards of the Workplace. J.B. Lippincott
Company, Philadelphia (1978), p.152.
12
Formaldehyde
As one of the 27 components identified within the Milky Way and with an
estimated 21 million tons annually produced worldwide, formaldehyde is
everywhere! It is indoors and outside, naturally occurring and manmade. It
is a by-product of combustion. It is used in the production of home and office
products. It is used in cosmetics, and it is in many of our foods both naturally
and as a contaminant.
Due to its ubiquitous nature and extensive use, formaldehyde was originally the target health hazard in indoor air quality investigations from the
late 1970s until just recently. Known health effects due to low-level exposures typically found in indoor air quality include irritation of the eyes, nose,
and throat. Symptoms may include watery eyes, burning eyes and nose,
and coughing. People chronically exposed to low levels may also experience asthma, chronic bronchitis, severe headaches, sleep disorders, chronic
fatigue, and nausea.1 In more severe cases, there may be lung irritation and
bronchospasm.
More elevated acute exposures may include coughing, wheezing, chest
pain and tightness, increased heart rate, and bronchitis. There have also been
reports of asthma attacks, nausea, vomiting, headaches, and nose bleeds.
Exposures in excess of that normally found in indoor air quality situations
(e.g., industrial exposures) may result in pulmonary edema, pneumonitis,
and death.
Dermal exposures may result in skin irritation, contact dermatitis, and
allergic sensitization. In some cases, symptoms involve eczema to the eyelids, face, neck, scrotum, and flexor surfaces of the arms. Sometimes dermal
exposures may involve the fingers, back of the hands, wrists, forearms, and
parts of the body exposed to friction.
There are several peculiar health effects of low-level formaldehyde exposures encountered in indoor air quality complaints that are not commonly
reported in industrial exposures. These include sleeping difficulties, anxiety,
fatigue, unusual thirst, dizziness, diarrhea, menstrual cramps, and memory
loss. In one instance, a woman thought low-level exposures in her mobile
home caused her to experience a feeling of persecution. People were allegedly following her, and she attacked an unsuspecting passerby and was later
arrested for attempting to strangle the stranger.
According to the American Conference of Governmental Industrial
Hygienists (ACGIH), formaldehyde is a suspect human carcinogen.
193
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Indoor Air Quality: The Latest Sampling of Analytical Methods
A sevenfold cancer risk occurred during industrial operations where
exposures were excessive, higher than that of the normal population.2
Although a volatile organic compound, formaldehyde is too volatile and
low in molecular weight to be captured and analyzed by the sampling methods for a broad spectrum of volatile organic compounds. For this reason,
formaldehyde is addressed separately herein.
Occurrence of Formaldehyde
In 1994, the U.S. Environmental Protection Agency (EPA) reported ambient
exposures in urban outdoor air environments to be 11 to 20 ppb. These exposures are in contrast to the more than 2.4 million mobile home dwellers that
are constantly exposed to an average of 400 ppb formaldehyde annually. The
range of reported exposures in homes is 0.10 to 3.68 ppm. See Table 12.1 for
formaldehyde exposure levels and associated health effects.
Environmental ambient air exposures are predominantly the result of
combustion byproducts with significant contributions from motor vehicle
exhaust. Other contributors are power plants, manufacturing facilities, and
incinerators. Heavy smog due to urban combustion may reach ambient air
levels as high as 0.1 ppm.
Indoors and outside combustion products that contribute to the formaldehyde levels include the following:
•
•
•
•
•
Gasoline
Wood
Natural gas
Kerosene
Cigarettes
TABLE 12.1
Formaldehyde Exposure Levels and Reported Health Effects
Exposure Level(s)
0.05–1.0 ppm
0.01–2.0 ppm
1.0–3.0 ppm
4.0–5.0 ppm
10.0–20.0 ppm
>50 ppm
Health Effects
pungent odor
eye irritation
irritation of eyes, nose, respiratory tract, throat,
and upper respiratory tract
unable to tolerate prolonged exposures
severe respiratory symptoms and difficulty
breathing
serious injury to the threshold
Formaldehyde
195
These source contributors are rarely considered significant contributors to
the formaldehyde levels indoors.
In office buildings, the most common indoor sources of formaldehyde
are off-gassing from building materials and office furnishings. Known
building materials that off-gas formaldehyde are formaldehyde-bonded
resin products such as foam insulation, plywood, particleboard, pressboard, wall panels, and wood finishes. The most commonly used indoor
resin is water soluble urea-formaldehyde. Outdoor resins are phenol- and
melamine-formaldehyde.
Other building materials potentially composed of urea-formaldehyde are
fiberglass HVAC duct board, fiberglass insulation, and carpet backings. New
office furnishings manufactured with formaldehyde-containing resins (e.g.,
veneered particleboard desks) are significant contributors to office formaldehyde exposures. Whereas formaldehyde off-gassing of furnishings generally
takes place within the first months of purchase, older furniture is rarely a
contributor to elevated levels of formaldehyde in the air.
Formaldehyde-containing products may also contribute to office and
residential exposures. These may include but are not limited to paper
products, deodorants, fabric dyes, inks, disinfectants, deodorizers, air
fresheners, cleaners, pesticides, preservatives, paints, and permanent
press clothing.
In residential environments, many of the same building products and furnishing found in office buildings are contributors to elevated levels of formaldehyde. Prior to strict manufacturing specifications and state regulations,
the highest residential exposures were associated with mobile homes and
conventional residences insulated with urea-formaldehyde foam.
In one report, “green rated” homes in California were found to have higher
levels of formaldehyde than conventionally built homes. The rationale is that
the green rated home were tighter, more energy efficient that those not rated.
They energy efficient home are more airtight and have minimal air infiltration of outside air.3
Beyond the previously mentioned airborne exposures, individuals inadvertently contribute to their own exposures by applying or using products that
contain formaldehyde. Formaldehyde is used in cosmetics, shampoos, pharmaceutical products, and permanent press clothing. If the container does not
state the presence of formaldehyde, look for Quaternium. Quaternium 15,
a formaldehyde release agent, and similar preservatives (e.g., diazolidinyl
urea) are found in conditioners, deodorant soaps, hairspray, styling mousse,
fluoride toothpaste, mouthwash, mascara, talcum powder, hair coloring, and
fingernail polish. These should be considered suspect wherein an individual
has localized dermal complaints.
The National Academy of Science estimates that 10 percent to 20 percent of
the general population is susceptible to the irritating properties of formaldehyde at levels below 0.1 ppm.4 In combination with other airborne irritants,
formaldehyde may also have an additive or synergistic impact of building
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Indoor Air Quality: The Latest Sampling of Analytical Methods
occupants. Be forewarned! Complaints of eye, nose, and respiratory tract
irritation may be the result of exposures to formaldehyde and a number of
other airborne contaminants. Low-level formaldehyde exposures may be
the cause of health complaint, but it may contribute to the overall effect. See
Table 12.1.
Some studies indicate that children exposed to 0.03 ppm had decreased
lung function. When exposed to levels between 0.60 and 0.12 ppm, children
were more likely to have asthma or chronic bronchitis.5
Relative humidity, temperature, air movement, and ventilation rates significantly affect formaldehyde off-gassing and airborne exposure levels.
For every 10°F increase in temperature, formaldehyde off-gassing doubles.
For an increase in relative humidity from 30 percent to 70 percent, the
off-gassing may increase as much as 40 percent. Increased air movement
will minimize stagnant air pockets and localization of gaseous formaldehyde at the point of off-gassing. Although ventilation flow rates will dilute
contaminated air, scenarios where the return air is in the immediate vicinity of the supply air may result in localized recycling and movement of air.
The ideal configuration, rarely encountered, is the return air and supply at
remote sites to one another or the air is diluted by outside air taken into the
HVAC system.
Sampling Strategy
At a minimum, samples should be taken within the area of greatest complaints, a noncomplaint area, and outside. The investigator should identify
these areas and be clear as to the worst case sites based on the complaints
and on odor. As there are no known direct reading instruments capable of
measuring formaldehyde at the levels generally found in indoor air quality
investigations, instrument screening is out of the question.
For exposure monitoring, samples should be taken within the vicinity of
the occupants’ breathing zones, not up in the far corner of the ceiling, and
all samples should be area samples, not personnel samples. The only occasion when sampling at ground level should be considered is when there is
concern regarding exposures to a small child. However, diagnostic sampling
is a separate issue.
Diagnostic sampling may be performed for source identification. This
may be done either during the exposure monitoring or after excessive
exposure levels have been determined. In all cases, several samples taken
at the same time will assist the investigator to contour an area regarding
relative concentrations. Whether taken during or after the initial exposure
monitoring, diagnostic samples should also include at least one exposure
Formaldehyde
197
sample taken at the same time. If the initial sample has already been taken,
take another at the same location. This will allow for changed conditions
and probable different exposure levels from one sampling period to the
next.
At a minimum, samples should be collected during those times anticipated to include excessive exposures, and the air handling system should
be operating as it generally is during complaint periods. In an office
building, if the complaints occur in the evening when the air handler has
been minimized, the samples should be taken in the evening with the
air handler minimized. Try to sample during those times and conditions
similar to when complaints occur.
At a minimum, samples should be collected for the length of time that will
allow detection to the level(s) targeted for concern. See flow rates, maximum
air sample volumes, and lowest detection limit in Table 12.2.
Other important sampling strategies involve anticipated physical state and
interferences. This topic is addressed in the next section.
Sampling Methodologies
Most formaldehyde air sampling methodologies collect on the basis of
physical state. Formaldehyde is a highly water soluble gas that readily
mixes with water to form formalin, which is a liquid. Formalin vapors
may or may not be captured by those methods that are meant only to collect the gas phase, and formalin vapors are just as irritating as formaldehyde gas. Should formalin become adsorbed onto dust particles, the gas
phase collection methods prefilter dust particles. Where dust may potentially carry formalin that contributes significantly to exposure levels and
health effects, choice of a gas collection method will result in incomplete
information.
Most of the air sampling methods (i.e., NIOSH 2016, NIOSH 2541, OSHA
52, and EPA IP 6A) will capture formaldehyde in its gaseous phase. They are
similar in equipment requirement, collection media and flow rate restrictions. The differences are in the detection limits (which in indoor air quality
are important), sampling duration, laboratory analytical methods, and interferences (or specificity).
Whereas the EPA IP 6A method involves longer sampling periods (up to 50
hours), greater detection limits (0.001 ppm), and may involve ozone interferences, Occupational Safety and Health Administration (OSHA) 52 involves
considerably less sampling duration, less detection limits (0.25 ppm), with no
interferences, and NIOSH 2016 requires less sampling duration with greater
treated silica gel sorbent
0.1
2
0.2–1.0
300 liters
1050 liters
36 liters
24 liters
100 liters
15 liters
Maximum Air
Sample Volume
0.001 ppm
0.0003 ppm
0.025 ppm
0.04 ppm
0.25 ppm
0.18 ppm
Lowest
Detection Limita
HPLC/UV
HPLC/UV
VAS
GC/NPD
GC/FID
HPLC/UV
Analytical
Methods
ozone
phenol and
oxidizable
organics
–
–
–
ozone
Interferences
Note: HPLC/UV = high pressure liquid chromatography/UV detector; GC/FID = gas chromatography/flame ionization detector;
GC/NPD = gas chromatography/nitrogen phosphorous detector; VAS = visual absorption spectrometry.
a Based on the published range and maximum air volume.
EPA IP-6A
(gas phase)
NIOSH 5700
(solid phase)
2 impingers in line with
10% sodium bisulfite
solution
5-micron PVC filter
NIOSH 3500
(all phases)
0.01–0.1
01–0.1
treated XAD-2 sorbent
treated XAD-2 sorbent
0.1–1.5
Flow Rate(s)
(liters/min)
treated silica gel sorbent
Collection Method
OSHA 52
(gas phase)
NIOSH 2016
EPA TO-11
(gas phase)
NIOSH 2541
(gas phase)
Method
Formaldehyde Air Sampling Methodologies
TABLE 12.2
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Formaldehyde
199
detection limits than the OSHA 52 method. Each of the gaseous phase sampling methods has a slight variation in capability, and in order to conduct a
thorough survey, the investigator must consider these differences and weigh
them against the sample information sought. For instance, the ASHRAE
189.1 limit for formaldehyde is 33 µg/m3 (or 26 ppb) and the LEED limit for
formaldehyde is 50ppb (see Chapter 19, “Green Buildings”). Both require
minimum sample duration of 4 hours. When attempting to attain these limits, NIOSH 2016 has become the preferred choice.
The NIOSH Method 2016 is the best all-around sampling method for minimal sample duration and detection limits. The sampling methodology is as
follows:
• Equipment: air sampling pump
• Capture media: silica gel treated with 2,4-dinitrophenylhydrazine
(e.g., SKC 226-119)
• Flow rate: 0.1 to 1.5 liters/minute
• Air volume limits: 15 liters
• Field blanks: minimum of one for up to ten samples in any given
sampling period
• Analysis: HPLC-UV detector
• Limit of detection: 0.1 µ/sample (6.7 µ/m3 for 15 liter sample)
• Special handling and shipping instructions: none
Experience comes knocking. On occasion, formaldehyde adheres to the
surface of dust particles, which are prefiltered prior to the solid sorbent.
Only gaseous formaldehyde gets through. NIOSH Method 3500 is a good
all around method for sampling the gaseous, liquid vapor (e.g., formalin),
and solid particle (e.g., formalin adsorbed onto the surface) phases of formaldehyde. Yet sampling is more difficult. The collection medium is a liquid
that is easy to spill (particularly when transferring the liquid into a small
plastic container for shipping) and during shipping, poorly sealed containers can leak. It is not unusual for a sample to arrive at a laboratory with
only a drop of liquid in the bottom of the container. Furthermore, during
extended sampling periods, the collection liquid vaporizes. Although the
liquid can be replenished as it vaporizes, the investigator must frequently
check the liquid levels during monitoring. This approach also requires
less sampling time while providing a good detection limit. Also, analytical interferences are minimal. In NIOSH 3500, phenol may be a positive
interference. Although low levels of phenol may contribute a 15 percent
bias, phenol is rarely encountered in indoor air quality investigations, and
separate sampling can be performed to rule out phenol. Slight negative
200
Indoor Air Quality: The Latest Sampling of Analytical Methods
interferences may also result from alcohols, olefins, aromatic hydrocarbons,
and cyclohexanone. This method also calls for the use of a 1-micron PTFE
membrane filter prior to the two impingers if the environment is dusty.
However, the use of a filter precludes formaldehyde adsorbed into the surface of particles. For this reason, an investigator may choose to use NIOSH
3500 without the filter particularly where there are no excessive levels of
dust. NIOSH 3500 method is summarized as follows:
• Sampling equipment: air sampling pump and two impingers
• Collection medium: 1% solution of sodium bisulfate (20 mL of solution per impinger)
• Flow rate(s): 0.2 to 1 liter/minute
• Field blanks: minimum of one for up to ten samples in any given
sampling period
• Sample duration: 100 minutes
• Detection limit(s): 0.025 ppm
• Handling: transfer sampled solution and ship in special 50 mL lowdensity polyethylene bottles
• Special considerations: most laboratories are no longer set up to analyze in accordance with NIOSH 3500
NIOSH 5700 was created specifically for sampling wherein formalin carrying dust is suspect. In some instances, the investigator may choose to use
this method with a gaseous phase method in order to assure collection of all
airborne formaldehyde/formalin. All other methods filter out the dust particles, potentially minimizing the actual airborne formaldehyde exposures.
There are no interferences and the detection level is low (e.g., 0.0005 ppm). A
summary of this method follows:
•
•
•
•
Sampling equipment: air sampling pump and inhalable dust sampler
Collection media: 25 mm PVC filter
Flow rate(s): 2 liters/minute
Field blanks: minimum of one for up to ten samples in any given
sampling period
• Sample duration: 36 to 180 minutes
• Detection limit(s): 0.025 ppm
• Handling: transfer sampled filter and ship in special 30 mL lowdensity polyethylene bottles
See Table 12.3 for a recap of the different methodologies.
201
Formaldehyde
TABLE 12.3
Formaldehyde Solid Sorbent Tubes
Method
NIOSH 2016/EPA TO-11
NIOSH 2541/OSHA 52
Type of Sorbent
Silica gel treated with
2,4-dinitrophenylhydrazine (DNPH)
XAD-2 treated with
10% (2-hydroxymethyl) piperidine
Analytical Methodologies
In NIOSH 2016, EPA TO 11, and EPA IP 6A, where the collection medium
is silica gel treated with 2,4 dinitrophenylhydrazine (DNPH), formaldehyde
combines with the DNPH on the silica gel to form a 2,4 dinitrophenylhydrazone derivative. The derivative is analyzed by high-pressure liquid chromatography with an ultraviolet light detector. Ozone may consume the DNPH
and interfere with the conversion of formaldehyde to the oxazolidine analyte.
Thus where elevated ozone levels are anticipated or known, these methods
may not be the best choice for sampling.
Where the collection medium is specially treated XAD 2, formaldehyde
combines with the 10% (2 hydroxymethyl) piperidine to form an oxazolidine
derivative. The derivative is analyzed by gas chromatography with a flame ionization detector. NIOSH 2541 calls for nitrogen phosphorous detector (NPD) in
order to increase the analytical sensitivity, and OSHA 52 specifically directs its
use. Although there are no observed interferences with either of these methods, acid mists may inactivate the sorbent, leading to inefficient collection of
formaldehyde. Thus where acid mists are anticipated or known, NIOSH 2541
and OSHA 52 may not be good choices of sampling methods.
In NIOSH 3500, also referred to as the “chromotropic acid method,”
formaldehyde, not a derivative of formaldehyde, is the actual analyte.
During sampling, the formaldehyde is settled out by the sodium bisulfite
solution. At the laboratory, it is mixed with chromotrophic acid and sulfuric acid. A color develops, and analysis is performed by visible absorption spectrometry. If there is interference by other aldehydes, the effect
is minimal.
In NIOSH 5700, the collected dust is extracted with distilled water and
mixed with 2,4 dinitrophenylhydrazine/acetonitrile (DNPH/ACN). The derivative is then analyzed by high-pressure liquid chromatography with an
ultraviolet light detector. This is similar to NIOSH 2016, EPA TO 11, and EPA
IP 6A and has the same ozone interference.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Helpful Hints
When performing NIOSH 3500, check frequently for retention of solution
and attempt to maintain the level up to 20 milliliters with fresh solution.
Upon sample completion, transfer each sampled solution to a separate properly labeled plastic bottle, clean, and add the extra to solution for transport
to the laboratory. Seal each bottle with a stretch tape (e.g., electrician’s tape)
and pull around the seam in the direction that the cap turns to allow for a
more airtight fit. Record the level of solution in the container prior to shipping and report it with the air volume for Impinger I (first impinger) and
Impinger II (backup).
Given a low flow rate and backup section or solutions, the investigator
may sample for a longer duration, sample greater air volumes, and get better detection limits with reliable results. For instance, if the investigator
samples for 5 hours instead of 2½ hours at a flow rate of 0.1 liters per minute
using NIOSH 2016, detection levels can be improved from 0.18 to 0.09 ppm.
Most experienced industrial hygienists will not push the envelope. If you
do, however, do it with a backup to confirm completeness and reliability of
the sample(s).
Interpretation of Results
The American Society of Heating, Refrigerating and Air Conditioning
Engineers (ASHRAE) 189.1 “maximum concentration limit” for formaldehyde
exposures in nonoccupatonal, indoor air quality assessments is 33 µg/m3
(or 27 ppm). The Leadership in Energy and Environmental Design (LEED)
limit is 50 ppm, twice that of ASHRAE 189.1.
Enforceable limits and nonenforceable exposure guidelines, referenced
in previous indoor air quality assessments, were 750 ppb (OSHA), 100 ppb
(WHO), 16 ppb (NIOSH), and 300 ppb (ACGIH). Formaldehyde is known
to cause eye irritation at 10 ppb, and the outdoor ambient levels have, in
some studies, been recorded as high as 100 ppb. There are no outdoor EPA
limits for formaldehyde, and the 100 ppb limit covers most, not all, health
concerns.
The maximum limits of 27 ppm, as set by ASHRAE 189.1, may not be attainable in all cases due to outdoor levels. In these rare circumstances, compare
the indoor with outdoor air samples. The ASHRAE guideline will be very
difficult to attain in indoor air quality. The environmental professional will
be required to make his or her own judgment!
Formaldehyde
203
Summary
There are pitfalls with each of the sampling techniques. The investigator
may use one or a combination of these methods, depending on the situation.
Consider the physical characteristics (e.g., gas versus carried by a solid), detection limits (0.0003 to 0.25 ppm), interferences (e.g., ozone), sampling duration
(2 to 50 hours), and ease of sample management. Sampling requirements will
vary, depending on each separate circumstance.
An action level for indoor air quality exposures is precarious and relative to other environments. The most commonly accepted limit of 0.1 ppm
has boundaries and exceptions as well. With each new case, the investigator
plays a new deck of cards!
References
1. Kincaid, L., and B. Offerman. Unintended Consequences: Formaldehyde
Exposures in Green Homes. The Synergist (February 2010), p. 31.
2. National Cancer Institute. Cancer Facts/Risk Factors. http://cancemet.nci.nih.
gov/clinpdq/risk/Formaldehyde.html (December 22, 2000).
3. Kincaid, L., and B. Offerman. Unintended Consequences: Formaldehyde
Exposures in Green Homes. The Synergist (February 2010), p. 31.
4. Formaldehyde Alert! http://members.tripod.com/gentlesurvivalistformaldehyde.
html (December 22, 2000).
5. Kincaid, L., and B. Offerman. Unintended Consequences: Formaldehyde
Exposures in Green Homes. The Synergist (February 2010), p. 31.
13
Product Emissions
Indoor exposures to organic compounds are typically two to five times
higher than those found outdoors. This is primarily attributed to emissions from construction materials, furnishings, office supplies/equipment, fixtures, and maintenance/cleaning products. Other contributing
sources include individual use products (e.g., perfumes and lighters) and
outdoor air pollutants. Indoor air pollutants are truly a wonderland of
surprises!
Then, indoor industrial exposures to toxic substances are generally
10 to 100 times those found in nonindustrial environments. This extreme
difference raises a skeptical eyebrow whenever environmental professionals respond to office building complaints. Exposures are much
lower in nonindustrial environments while complaints are greater. Why
are the health complaints in office buildings disproportionate to those
in industry?
Some feel the discrepancies lie in the complex array of chemical exposures in offices and other nonindustrial environments. Furthermore, nonindustrial environments are generally exposed to low levels of more than 300
chemicals—an amalgam that may exceed high industrial exposure levels to
a limited number of chemicals. The combination of overwhelming numbers
and the synergistic irritant/health effects of indoor air contaminants set the
stage for occupant health complaints. This scenario is exacerbated by type
of containment(s) and level of buildup.
Due to increased energy efficiency needs and reduced makeup air, indoor
air is ripe for the buildup of airborne contaminants. Whereas in industrial
environments chemicals are removed by local exhaust and dilution ventilation, energy efficient, tight buildings retain most air contaminants. Trapped
chemicals do not a good bedfellow make!
From whence do the chemicals come? They come from components of
furnishings, equipment, fixtures, flooring, and cleaning products, a medley
of trapped chemicals. In new buildings, construction materials and products contribute significantly as well. The pressure cooker builds! There is no
place for chemicals to escape. Subsequently, product emissions in confined,
occupied spaces have become the bane of “sick building syndrome.” What
to do?
205
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Global Response and Product Labeling
As early as 1978, the Germans introduced the “Blue Angel.” This was, and still
is, a certification program for environmentally “friendly” products and services.
Other countries began to mimic the Germans and began developing their own.
Out of this arose the Nordic Swan, Canadian Environmental Choice, U.S. Green
Seal, and others—all eventually becoming part of an international cooperative.
In 1994, Global Ecolabelling Network (GEN) was formed to put a global
face on labeling. Its express purpose was to “improve, promote, and develop
the ‘ecolabelling’ of products and services.” By 2007, membership had grown
to include 26 nations and multinational organizations (see Table 13.1).
TABLE 13.1
Global Ecolabelling Network Members
Australia
Brazil
China
Croatia
Czech Republic
EU
Germany
Hong Kong (GC)
Hong Kong (HKFEP)
India
Indonesia
Japan
Korea
New Zealand
Nordic Five Countries
North America (Canada)
North America (USA)
Philippines
Russia
Chinese Taipei
Singapore
Sweden (SSNC)
Sweden (TCO)
Thailand
Ukraine
United Kingdom
Good Environmental Choice Australia Ltd.
Associacae Brasileira de Normas Tecnicas (ABNT)
China Environmental United Certification Center
Ministry of Environmental Protection and Physical Planning
Ministry of the Environment
European Commission–DG Environment (G2)
Federal Environmental Agency (FEA)
Green Council
Hong Kong Federation of Environmental Protection (HKFEP)
Limited
Central Pollution Control Board (CPCB)
Ministry of Environment
Japan Environment Association (JEA)
Korea Eco-Products Institute (KOECO)
Environmental Choice New Zealand
Nordic Ecolabelling Board
Terra Choice Group Inc./Terra Choice Environmental
Marketing, Inc. (for Environment Canada)
Green Seal
Clean & Philippine Center for Environmental Protection and
Sustainable Development, Inc. (PCEPSDI)
Saint-Petersburg Ecological Union
Environment and Development Foundation (EDF)
Singapore Environment Council
Swedish Society for Nature Conservation (SSNC)
TCO Development
Thailand Environment Institute (TEI)
Living Planet
Department for Environment, Food and
Rural Affairs (DEFRA)
Product Emissions
207
Ecolabeling is a voluntary method of environmental performance certification and labeling that is practiced around the world. An “ecolabel” is a
label that identifies overall environmental preference of a product or service within a specific product/service category based on “life cycle considerations.” In contrast to “green” symbols or claim statements developed by
manufacturers and service providers, an ecolabel is awarded by an impartial
third party in relation to products or services that are independently determined to meet environmental leadership criteria.1
Standards of Green Seal, a U.S. component of GEN, meets criteria as set
forth in: (1) ISO 14020 and 14024, the standards for ecolabeling; and (2) the
U.S. Environmental Protection Agency (EPA). Currently, the Green Seal label
is limited to industrial/institutional cleaners and paints.
Although not in the Global Ecolabelling Network, Green Label is an
industry-monitored, third-party certification for carpets and carpet pads
that is managed by the Carpet and Rug Institute (CRI). The Green Label and
Green Label Plus programs certify the “lowest” emitting carpet, backingadhesive, and cushion products on the market.
In 2001, a U.S. based emissions testing laboratory established the
GREENGUARD Environmental Institute (“GREENGUARD”) to test and
certify indoor air emissions from office furniture and office equipment.
GREENGUARD, which is the only ISO 65 accredited certification program
in the United States, developed the initial testing methodology for office
furniture through EPA’s Environmental Technology Verification Program.
GREENGUARD had previously been accredited by Germany’s Federal
Institute for Materials Research and Testing for providing acceptable
data for the Blue Angel Eco Label Program. Today, it has developed testing methodologies that not only evaluate office equipment and furniture
but much more. It performs third-party testing and certification for the
following:
• Cleaners and cleaning maintenance products
• Office, institutional, and residential furniture
• Office equipment (e.g., printers, multifunction machines, fax machines,
and copiers)
• Building materials, finishes, and indoor furnishings
• Electronic equipment (e.g., computers, video monitors, and televisions)
As public concerns escalate, manufacturers and builders seek to produce
low-emission products. The downside is cost. It is speculated that the cost for
going “green” increases product costs 20 percent or more. The cost difference
may change as the market adapts, but for now, end user “suspect” product
emissions testing is a viable alternative!
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Product Emissions Awareness
Product emissions testing had been the wave of the future, and the future is
upon us. Testing is with greater frequency becoming a mandate. The manufacturers who seek Global Ecolabelling Network certification are limited as
to what can be certified. Building owners request environmentally friendly
or “green” products and request information to this effect from the manufacturers and suppliers. If the products are not labeled, and most aren’t, the
salesperson may say, “Trust me! My product has no emissions” or, “We have
never had any complaints.” They are likely, however, to seek validation from
the manufacturer who also wants to make a sell.
Most products are a composite of multiple intermediate products. For
instance, the components that make up a desk include plywood, laminate
adhesives, glues, stains, varnishes, and shellac. Hence, a manufacturer who
has a genuine desire to provide information often finds the task of compiling
all the data (e.g., MSDS) can be overwhelming. Emissions testing is expensive and time-consuming. The price tag of furniture that has already been
tested may override the cost of purchasing a pig in a poke and testing later.
Many facility managers require prefurnishing and postfurnishing air
monitoring prior to occupying a new office building. Postoccupancy air
monitoring is generally, not always, complaint driven. Wherein air monitoring demonstrates chemical levels of concern, the environmental professional
may seek to identify suspect products for testing. Identifying the culprit(s)
requires product emissions awareness!
In indoor air quality, air contaminants most frequently encountered are
volatile organic compounds (VOCs) and formaldehyde (see Table 13.2). VOC
exposures are chemical specific. Formaldehyde, an organic compound, can
cause eye irritation (inflammation, redness, itching, and watery) and is listed
as a suspect human carcinogen by the American Conference of Governmental
Industrial Hygienists (ACGIH).
Carpet and carpet backing off-gas both VOCs and formaldehyde. Of the many
identified VOCs, 4-phenylcyclohexene (4-PCH) is the target component that has
received the most attention. Generally associated with wall-to-wall, rubberbacked carpeting, 4-PCH gives off a distinctive “new carpet” odor and causes
nose and upper respiratory tract irritation. 4-PCH is a “by-product” of the copolymerization of styrene-butadiene when the conditions are not optimal. In one
headspace emissions study, 4-PCH was the most abundant of 10 VOCs found
in carpet made with laminated fabric backing. Air concentrations measured in
buildings after installation of new carpet has been reported at 0.3 to 2.6 ppb.3
Carpet component 4-phenylcyclohexene
Recommended exposure limit—none
Odor threshold—0.3 ppb (2 µg/m3)
209
Product Emissions
TABLE 13.2
Products That Result in VOC and Formaldehyde Emissions2
Volatile Organic Compound Emissions
Formaldehyde Emissions
Paints
Fabrics and fabric treatments
Cushions (polyurethane/polystyrene foam
and polyester stuffing)
Plastics (various plasticizers)
Adhesives
Cleaning solvents
Carpet and other flooring
Particleboard
Plywood
Pressboard
Paneling
Cabinetry
Carpet/carpet backings
Dyes
Household cleaners
Wrinkle-resistant fabrics
Glues
Resins
Insulation
Foam
Laminates
Plastics/moldings
Stiffeners
Water repellents
In a German study, 4-PCH was rated as “odor active” and contributed to
poorly perceived indoor air quality.”4 They reported that low-level exposures
of 4-PCH and other VOCs were associated with headaches, eye irritation,
and nausea.5
In 1989, the Consumer Product Safety Commission and the EPA performed a
study of new carpet emissions and the adverse effect on human health. There
were 206 households involved in new carpet installations and no controls.
Relative incidences were not reported either. So the reported symptoms are a
composite, not related to frequency. The symptoms began either immediately
or within several days of newly installed carpet. Reporting included upper
respiratory tract problems; eye irritation; headaches; rashes; fatigue; difficulty
in concentration; headaches; nausea; excessive thirst; dry mouth; burning of
the eyes, nose, and sinuses; incoherent speech; depression; sore throat; itchy
skin; burning feet and legs; chronic rhinitis; and dry, puffy, irritated lips.
The CRI Green Label Plus only assures the customer of “very low” VOC
emissions. The label is no assurance that the carpet is free of VOCs. Under
the program, all carpet products are tested by an independent laboratory.
Thirteen chemicals that have been identified with carpet are:
• Acetaldehyde
• Benzene
210
•
•
•
•
•
•
•
•
•
•
•
Indoor Air Quality: The Latest Sampling of Analytical Methods
Caprolactam
2-Ethyhexanoic acid
Formaldehyde
1-Methyl-2-Pyrrolidinone
Naphthalene
Nonanal
Octanal
4-PCH
Styrene
Toluene
Vinyl acetate
Carpet adhesives are tested separately. Fifteen identified chemicals are:
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Acetaldehyde
Benzothiazole
2-Ethyl-1-hexanol
Formaldehyde
Isooctyacrylate
Methylbiphenyl
1-Methyl-2-Pyrrolidinone
Naphthalene
Phenol
4-PCH
Styrene
Toluene
Vinyl acetate
Vinyl cyclohexene
Xylenes (m-,o-,p-)
Furniture also off-gasses volatile organic compounds and formaldehyde.
Wood furniture is frequently made of plywood and particleboard made with
urea-formaldehyde glue that emits high levels of formaldehyde when new.
Phenol-formaldehyde and resorcinol are low emitters of formaldehyde. Solid
wood is a nonemitter.
Polyurethane foam (e.g., seat cushions) is blown in by hydrofluorocarbons that are being phased out. Alternative agents are isoproprene, acetone,
211
Product Emissions
pentane, and carbon dioxide with limonene and terpene. Polyurethane is also
treated with polybrominated diphenyl ethers (PBDEs)—a flame retardant.
Lamination requires solvent-based adhesives with high VOC emitters.
Paints, stains, varnishes, shellacs, and lacquers emit VOCs. Allegedly, most
manufacturers have converted to low emitter or no emissions paints and lacquers. Oil-based paints, varnishes, shellacs, and lacquers are all high emitters of a barrage of VOC including methanol.
Sensory Irritation Testing in Environmental Chambers
Toxicological testing that is based on environmental chamber technology and animal inhalation studies are performed to address sensory irritation caused by airborne chemicals. Product emissions are introduced
in a chamber housing laboratory animals. The breathing patterns and
other clinical responses are then monitored. Challenges are singular or
multiple.
There have been isolated instances of human irritation testing using environmental chambers. For example, a researcher who has received considerable attention internationally used chamber challenge testing to develop a
dose response relationship for discomfort due to volatile organic compounds.
See Table 13.3 for a summary of his findings.
There have been attempts by some researchers to perform challenge testing without the benefit of a chamber or known, monitored levels of exposure. Yet as the chemical exposure levels are poorly controlled, the results
are questionable. There is also concern for life-threatening patient reactions
that could result in medical emergencies. For these reasons, human challenge testing is rare in the United States.
TABLE 13.3
Summary of Research Findings on Effects
of Total Volatile Organic Compound
(TVOC) Mixtures6
TVOC (mg/m3)
Health Effects/Irritancy Response
<0.20
0.20–3.0
3.0-25
>25
No response
Irritation and discomfort
Discomfort (probable headache)
Neurotoxic/health effects
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Product Collection
In the United States, there are no hard, fast mandates for product emissions
sampling. Green Seal covers cleaning fluids. Green Label covers carpets and
carpet pads. The GREENGUARD Environmental Institute, an American
National Standards Institute (ANSI) accredited standards developer, published its standards and testing methodologies in 2002 for a variety of construction materials and furnishings. In 2010, the GREEN Building Initiative
(GREEN Globes) published the first ANSI accredited green building rating
system with established emissions testing protocols. ANSI/American Society
of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) 189.1,
“Standard for the Design of High Performance Green Buildings” (ASHRAE
Standard) was published in 2010, covering products and air emissions in
office buildings and institutions. The GREEN Building Standard as published by the National Home Builders Association covers standards for residential construction.
Within the ASHRAE Standard, the project committee defered to California
Specification 01350 (“Specification”) for protocols to perform materials emissions testing of building components and contents. The Specification is
titled “Standard Practice for the Testing of Volatile Organic Emissions from
Various Sources Using Small-Scale Environmental Chambers,” and the
Specification is “generally consistent with the (2002) European Committee
for Standardizations PrEN13419-3.”7 Introductory comments in the Sample
Collection Section include the following:8
• If the sampling is done improperly, the sample is in error and any
subsequent analysis is invalid.
• Samples shall be representative of the product manufactured and
produced under typical operating conditions.
• Special care shall be taken to prevent contamination of the product sample from any external sources (e.g., solvent-containing
products such as stored paint) prior to, during, and after sample
collection.
• Samples must be stored immediately after collection in airtight,
moisture-proof containers/packaging to prevent contamination and
to preserve their chemical integrity by preventing subsequent VOC
emission losses.
• Sampling location/site shall be selected to allow for reproducible,
easy access to representative cross-sections of the product category.
With the exception of containerized products, samples shall be collected and
shipped from the manufacturing facility within one week of the actual production completion date.
213
Product Emissions
The California Specification is for collection and analysis of newly manufactured building materials only (see Table 13.4) and not entire components (e.g.,
office partitions and desks). There are also limited laboratories in the United
States that have environmental chambers for emissions testing on larger items.
GREENGUARD Environmental Institute is one such laboratory—with
considerable expertise in certifying manufacturer products and in testing
large item single- or multiple-purchase consumer products. Their sample
collection procedures are similar to those of the California Specifications
with but a few additions—items that are not otherwise included. Thus the
sample collection approach for the office equipment, large furnishings, and
electronic equipment is expanded upon in Table 13.5.
TABLE 13.4
Sample Collection Procedures as Recommended by California Specification 01250
Group Material Type
Sample Collection Procedure
Tile, strip, panel, and plank
(less than 2 feet wide)
VCT, resilient floor tile, linoleum tile, wood floor strips,
parquet flooring, laminated flooring, modular carpet tile
1. Collected directly off the packing line
2. Minimum of four representative tiles, strips, or planks—
minimum 64 square inch total (e.g., four 4 inch × 4 inch
pieces)
3. Stack and pack in two layers of heavy-duty aluminum foil
(seal with clear packaging tape)
4. Label and place foil wrapped samples in polyethylene or
Mylar bag
5. Seal bag with tie wrap
6. No more than 1 hour between collection and packing
Sheet and roll goods
(greater than 2 feet wide)
broadloom carpet, sheet vinyl, sheet linoleum, carpet cushion,
wall coverings, other fabric
1. Collected within 24 hours of productions directly from end
of the product roll.
2. Minimum of 2 yards or two full circumferences from the end
of the roll
3. A 1 foot wide strip of material shall be cut across the width
of the roll, at least 1 foot discarded from each end of the
strip—minimum of four 1 foot × 1 foot squares
4. Wall coverings and other fabrics may be collected as a full or
partial production roll with minimum of 10 layers of wrap
5. Stack and pack in two layers of heavy-duty aluminum foil
(seal with clear packaging tape)
6. Label and place foil wrapped samples in polyethylene or
Mylar bag
7. Seal bag with tie wrap
8. No more than 1 hour between collection and packing
(continued)
214
Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 13.4 (CONTINUED)
Sample Collection Procedures as Recommended by California Specification 01250
Group Material Type
Rigid panel products
(greater than 2 feet wide)
Sample Collection Procedure
gypsum board, other wall paneling, insulation board, oriented
strand board (OSB), medium density fiberboard (MDF),
plywood, particleboard, etc.
1. Collected within 24 hours of productions directly from end
of the product roll
2. Select a panel at least 3 panels down from the top of the stack
3. For large panel products, the sample shall be taken at least
6 inches away from all edges of a panel.
4. Cut panel into four 1 foot × 1 foot pieces
5. Stack and pack in two layers of heavy-duty aluminum foil
(seal with clear packaging tape)
6. Label and place foil wrapped samples in polyethylene or
Mylar bag
7. Seal bag with tie wrap
8. No more than 1 hour between collection and packing
Fiberglass insulation batt
products
Containerized products
1. Collected directly off the packing line
2. Cut four 2 foot long sections across the width of the batt
3. Stack, compress, and pack in two layers of heavy-duty
aluminum foil (seal with clear packaging tape)
4. Label and place foil wrapped samples in polyethylene or Mylar
bag
5. Seal bag with tie wrap
6. No more than 1 hour between collection and packing
adhesives, sealants, paints, other coatings, primers, and other
“wet” products
1. Paints, other coatings and primers can be supplied in
original, standard, 1-quart or 1-gallon consumer containers
2. If less than 1 gallon consumer packaging, adhesives can be
supplied in their consumer containers (e.g., applicator tube
or can)
3. If greater than 1 gallon packaging, adhesives can be
collected in clean, unused paint 1-pint or 1-quart size cans.
They should be filled to eliminate headspace, and the
collection method should be documented
4. Affix MSDS, specification sheet for the product, sample label
with manufacturer and sample ID, date and time of sample
collection
Beyond “dynamic environmental chamber” emissions testing, many of
the larger environmental/industrial hygiene laboratories perform small
scale, headspace sampling of some of the smaller building components.
As laboratories may vary from the California Specifications and Green
Environmental Institute Procedures in their headspace protocols, consult
215
Product Emissions
TABLE 13.5
Sample Collection Procedures as Recommended by GREENGUARD
Environmental Institute
Group Material Type
Tile, strip, panel, and plank
Sheet and roll goods
Rigid panel products
Hardcopy devices
Containerized products
Insulation
Furniture and other large
products
Sample Collection Procedure
Similar to Table 13.4
Similar to Table 13.4
Similar to Table 13.4
printers, multifunctional machines, fax machines, and copiers
1. Select products representative of similar products by the
manufacturer
2. The product shall not be treated differently from others
3. The product may be a prototype—identical to the latter
serial product
4. Product shall be packaged using the manufacturer’s
standard packing
5. Enclose sample details—sample ID, manufacturer, machine
name, machine type, test mode(s), filter, device number
(Serial #), toner/cartridge numbers, paper used (type and
size), date manufactured
6. If not from factory, consult with testing laboratory
7. Fill out laboratory chain of custody
Similar to Table 13.4
fiberglass batting, board and rigid foam, blowing wools and
loose fill, spray foam insulation
1. Fiberglass batting collection similar to that of Table 13.4
2. Boards and rigid foam boxed at the factory should be
allowed to condition for 15 minutes. Manufacturers who
wish to provide Greenguard Certified products for furniture
panel applications will be expected to deliver product for
the purposes of emissions testing in the same fashion as
standard board products (more details available by
GREENGUARD laboratory)
3. Blowing wools and loose fill should be collected from the
compressed or evacuated product package 15 minutes
following packaging. Loose fill insulation shall be placed in
a specialized packaging bag, fill about 66% to 75% of the bag
4. Spray foam insulation (closed cell foam)—spray 1 foot × 1
foot sample thickness, based on stud size (e.g., 3.5 inch or
5.5 inch) with one or two passes, 1.5 to 2 inch thick. Wait
1 hour and place in Mylar bag
5. Spray foam insulation (open cell foam)—spray 1 foot × 1
foot sample to thickness of 3.5 feet to 4 inches for walls and
6 inches for attics. Scarf the sample of excess foam. Wait 24
hours and place in Mylar bag
1. Furniture and other large products shall be collected
immediately following manufacturing and packed in
accordance with manufacturer’s standard packing practices
(e.g., shrink wrap and cardboard box). For more details,
consult with testing laboratory
216
Indoor Air Quality: The Latest Sampling of Analytical Methods
with the laboratory of choice as to their recommended practices for sample collection.
Environmental Chamber and Analytical Methodology 9,10,11,12,13
Environmental chamber testing is quantitative and qualitative for projecting product emissions in indoor environments. In the United States, the
most frequently referenced protocols for chamber testing are the American
Society for Testing and Materials (ASTM) published “Standard Guide for
Small-Scale Environmental Chamber Determinations of Organic Emissions
from Indoor Materials” (ASTM D5116) and “Standard Practices for FullScale Chamber Determination of Volatile Organic Emissions from Indoor
Materials/Products” (ASTM D6670). The most comprehensive testing methodology incorporating these principles for small and large scale chambers
is available from the GREENGUARD Environmental Institute, “Standard
Method for Measuring and Evaluating Chemical Emissions from Building
Materials, Finishes and Furnishings Using Dynamic Environmental
Chambers.” This methodology incorporates the principles of California
Specification 1350 but is extended to additional products including office
furniture. Chamber designs simulate indoor environments by artificially
controlling temperature, humidity, and air flow. The incoming air is
stripped and cleaned of contaminants and air exchange rates established
(e.g., two room changes per hour) in accordance with ASHRAE Standard 62.1
recommendations.
After a defined preconditioning period (outside the chamber), materials/
products (e.g., small samples or whole furnishing modules) are placed in or
material (e.g., paint) applied onto a surface inside a chamber. The chamber
is closed, and the humidity, temperature, chamber air exchange rates, and
air movement are maintained at a constant setting until such time as the
assigned enclosure time has lapsed and all chamber air testing has been
completed.
The prescribed period of time for material/product confinement is based
of product size and number of air samples required. Smaller, single sample
products may be completed within 24-hours (i.e., one day). Large, multiple
sample products may take up 720 hours (i.e., one month). Thus the time
required to complete an analysis (i.e., precondition time and chamber testing time) is one day to more than a month.
After background air testing and product loading, chamber air samples are
collected at intervals determined by the laboratory and product type being
tested. For example, initial, unspecified Greenguard Certification chamber air testing is performed 6 hours, 24 hours, 48 hours, 72 hours, 96 hours
(or 120 hours), and 168 hours (i.e., one week). Electronic product chamber
Product Emissions
217
FIGURE 13.1
Large scale emissions testing chamber—greater than 25 m3 volume, used for large products.
(Courtesy of Air Quality Sciences, Inc., Marietta, Georgia)
testing is done within 30 minutes of loading and taken at 1.5 hours, 2.5 hours,
4 hours, and 8 hours.
At the predesignated sample intervals, air samples are extracted directly
from the multiple ports in chamber exhaust. Chamber emissions air sample
media and analytical methods are as follows:
• Total and identified volatile organic compounds—thermally desorbed, solid-phase sorption tubes analyzed by TO-1 and TO-17
• Formaldehyde and other low molecular weight aldehydes—solid
sorbent (e.g., silica gel) treated with an acid solution of 2,4-dinitrophenylhydrazine (DNPH) analyzed by high pressure liquid
Chromatography (HPLC)
• Phthalates—OVS Tenax analyzed by gas chromatography flame
ionization detector (GC/FID)
218
Indoor Air Quality: The Latest Sampling of Analytical Methods
• Ozone—direct reading UV absorbance based ozone analyzer
• Dust—47 mm GF-50 glass filter analyzed by gravimetric
measurement
• Respirable particles (P10)—direct reading laser photometer aerosol
monitor with less than 10 micron setting
The emissions air sample results (i.e., concentration in chamber), chamber
air exchange rate, and ratio of product to chamber air volume (i.e., product
loading) are used to calculate the emission factor—at any given point in
time. For example, annual Greenguard Certification testing requires emission factor determination at the end of 168 hours chamber time.
The emission factor is used to compare emission levels among products at
a specific exposure time—in the chamber. The formula is as follows:
EF = C ×
N
L
EF = Emission factor in µg/m2 • hour (surface area) or µg/unit • hour
(product)
C = Concentration in chamber in µg/m3
N = Chamber air exchange rate (e.g., number of room changes/hour)
L = Product loading in m2/m3 (surface area) or unit/m3 (product)
The concentrations in the chambers are neither a reflection nor a prediction of
anticipated exposure concentrations in indoor air environments. The “emission
rate” is calculated to predict exposure concentrations in buildings. Factors are
calculations based on chambers, and rates are calculations based on building
environmental parameters.13 The preceding parameters include air movement,
amount of makeup air, air volume of room(s), and level of occupant activity.
Where not performing annual Certification renewals (e.g., at the end
of 168 days) or special single test requests after a given time period (e.g.,
five-day special request), chamber air sampling has been performed initially,
at intervals, and at the end of the chamber testing. The emission rates for
TABLE 13.6
Building Parameters for Office Buildings14
Parameter
Room length
Room width
Room height
Room volume
Air exchange rate
Number of units
GG Office Model
10 ft
14 ft
8 ft
32 m3
0.72 hr-1
1
Product Emissions
219
each of the chemicals (sampled at various intervals) are compiled, and the
chamber data for those products that do not have constant emission factors
is feed to a computer. “Predicted air concentrations” for specified indoor air
environments (e.g., offices) are thus determined by computer modeling.
Measurements of Product Emission Factors
Emissions from a product are measured in terms micrograms (µg) of chemical off-gassed from a solid product (e.g., foam), liquid (e.g., paint), or a composite unit (e.g., chair). Solid product emission factors/rates are based on
exposed surface area(s) per hour [i.e., micrograms per square meters-hour
(µg/m2-hour)]. Liquid is based on relative mass in an hour [i.e., micrograms
per gram-hour (µg/g-hour)], and composite units are based on units in an
hour [micrograms per composite-hour (µg/unit-hour)].
One study compares emission factors from office furnishings—chamber
emissions. Findings were as follows:2
• Modular desks
• Volatile organic compounds–160 to 45,000 mg/workstation-hour
• Formaldehyde–802 to 3780 mg/workstation-hour
Chairs
• Volatile organic compounds–159 to 450 mg/chair-hour
• Formaldehyde–no detection to 1670 mg/chair-hour
Tackable acoustical partitions (with phenol-formaldehyde treated fiberglass insulation)
• Volatile organic compounds–0.006 to 0.074 mg/m2-hour
• Formaldehyde–0.158 to 0.37 mg/m2-hour
In the above study, modular desks are the highest emitters of both VOCs
and formaldehyde. Also of particular interest, acoustical partitions that were
treated with phenol-formaldehyde resins off-gassed considerably less formaldehyde than urea-formaldehyde products (e.g., desks and chairs).
Another brief study reported emission factors for products used to build
furniture. See Table 13.7. The chamber comparison of product emissions is
interesting in that even water-based adhesives off-gassed high levels of VOCs.
Wood stains off-gassed more VOCs than polyurethane lacquer. Textiles may
off-gas more formaldehyde than some wood products, and insulation did, at
the time of the study, off-gas formaldehyde.
220
Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 13.7
Reported Highest Emissions from Products
Used to Build Furniture2,15
Product
Emission Factor
(µg/m2-hour)
Volatile Organic Compounds
Solvent-based adhesives
Water-based adhesives
Furniture spray polish
Wood stain
Polyurethane lacquer
Plywood
Polystyrene foam
Particleboard–fiberboard
Hardboard
Medium density fiberboard
Formaldehyde
Wood products
Insulation
Wall coverings
Textiles
17,000,000
2,100,000
300,000
17,000
6,000
2,400
1,400
150
30
40
170–900
16–26
20–600
0–3,000
Note: Study is limited in scope therefore not to be considered conclusive or all encompassing regarding all products. Variations will occur between
product types, manufacturers, formulations, and
production processes.
A study involving formaldehyde emissions from finished wood product
harbors a different focus, a different enlightenment in the world of strange,
unforeseen consequences following water damage and finished/unfinished
wood products (see Table 13.8). Water damaged chipboard off-gases four
times more formaldehyde than nonwater damaged chipboard. Unfinished
wood products off-gas more formaldehyde than finished boards.
Interpretation of Results
In the absence of U.S. federal standards for indoor air quality pollutants or
product emissions limits, several programs are recognized as providing
voluntary guidelines and recommendations. These include the U.S. Green
Building Council’s LEED programs where office furniture is required to meet
the GREENGUARD criteria for office furniture as noted in Table 13.9, and
all other products must meet the testing and chemical criteria as prescribed
221
Product Emissions
TABLE 13.8
Highest Formaldehyde Emissions from Finished
Wood Products2
Concentrations
(µg/m3)
Material
Unfinished medium density fiberboard (MDF)
Unfinished particleboard
Finished particleboard
Finished MDF
Water-damaged chipboard
Nonwater damaged chipboard
970
809
719
246
48
10
in California Specification 1350. The recent ANSI/ASHRAE 189.1 Standard,
“Standard for the Design of High-Performance, Green Buildings—Except LowRise Residential Buildings,” provides a “limited list of acceptable emissions factors” for office furniture systems and furniture components. The Standard only
addresses total VOCs, formaldehyde, total aldehydes, 4-PCH as in the LEED
program, but it has added 31 additional VOCs that are primarily VOCs with
established California Chronic Reference Exposure Limits (CREL). This standard is limited to high-performance (e.g., large office buildings). This is not to
say that the Standard cannot be applied to other situations, but, once again, it is
limited. See Tables 13.9 and 13.10.
The ANSI/ASHRAE Standard frequently defers to the California “Standard
Practice for Testing Volatile Organic Emissions from Various Sources Using
Small-Scale Environmental Chambers.” The California limits are more
extensive and focused on the entire environment and maximum exposure
limits to building occupants in terms of Chronic Relative Exposure Limits
(i.e., Chronic REL, CREL) as well as carpet emissions, based on the predicted
air concentrations for each given chemical for a given environment (e.g., 2200
square foot residence). Each product must not exceed 50 percent of the CREL
for each chemical listed, and the composite of all products in a given indoor
environment must not exceed the actual CREL.
TABLE 13.9
Workstation Systems and Seating Office Emissions
Concentration Limits
Chemical
Contaminant
TVOC
Formaldehyde
Total aldehydes
4-PCH
Workstation
Emission Limits
Seating Emission
Limits
0.5 µg/m3
50 ppb
100 ppb
0.0065 mg/m3
0.25 µg/m3
25 ppb
50 ppb
0.00325 mg/m3
222
Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 13.10
Individual VOC Allowable Concentrations/Emission Factors for Office
Furniture Systems
Chemical
1,1,1-trichloromethane
(methyl chloroform)
1,4-dichlorobenzene
1,4-dioxane
1-methoxy-2-propanol
(propylene glycol
monoethyl ether)
1-methyl-2-pyrrolidinone
2-ethoxyethanol
2-ethoxyethyl acetate
2-methoxyethanol
acetaldehyde
benzene
carbon dixulfide
chlorinated dioxins &
dibenzofurans
chlorobenzene
chloroform
dimethyl formamide, N,Nepichlorohydrin
ethylbenzene
ethylene glycol
formaldehyde
gluteraldehyde
hexane (n-)
isopropanol
methylene chloride
monomethyl ether acetate
naphthalene
phenol
styrene
tetrachloroethylene
toluene
trichloroethylene
vinyl acetate
xylene (m-,o-,-p)
Private
Open Plan
Office
Workstation
Seating
Maximum Maximum
Maximum
Maximum Allowable Allowable
Allowable
Allowable
Emission Emission California
Concentration Concentration
Factor
Factor
CREL
µg/m3
µg/m3
µg/m2-h
µg/m2-h
µg/m3
500
250
345
696
1000
400
1500
3500
200
750
1750
278
1034
2413
557
2,089
4874
800
3000
7000
160
35
150
30
9
30
400
–
80
17.5
75
15
4.5
15
200
–
110
24
103
21
6
21
276
–
223
4.9
209
42
13
42
557
–
–
70
300
90
140
60
800
0.0004
500
150
40
1.5
1000
200
16.5
–
3500
3500
200
45
4.5
100
450
17.5
150
300
100
350
250
75
20
0.75
500
100
8.25
–
1750
1750
100
22.5
2.25
50
225
8.75
75
150
50
175
345
103
28
1
689
138
11
–
2413
2413
138
31
3
68.9
320
12.1
103
207
68.9
241
696
209
56
2.1
1392
278
23
–
4874
4874
278
63
6
139
627
24.4
209
418
139
487
1000
300
80
3
2000
400
9
0.08
7000
7000
400
60
9
200
900
35
300
600
200
700
223
Product Emissions
TABLE 13.11
California Chamber Emissions Testing Limits for Carpeting
Full 14-Day Emissions Chamber Test
Additional 24 Hours and Annually
caprolactam—100 µg/m3
2-ethylhexoic acid—25 µg/m3
1-methyl-2-pyrrolidinone—160 µg/m3
nonanal—13 µg/m3
octanal—7.2 µg/m3
3-phenylcyclohexene—2.5 µg/m3
styrene—220 µg/m3
caprolactam—70 µg/m3
2-ethylhexoic acid—25 µg/m3
1-methyl-2-pyrrolidinone—NA
nonanal—13 µg/m3
octanal—7.2 µg/m3
3-phenylcyclohexene—2.5 µg/m3
styrene—220 µg/m3
acetaldehyde—4.5 µg/m3
benzene—30 µg/m3
formaldehyde—16 µg/m3
toluene—150 µg/m3
The Chronic REL is intended to protect those who are both healthy and
those who are environmentally sensitive to chemicals 24 hours a day for
more than 10 years. A few of the more than 90 substances with assigned
Chronic RELs can be found on Table 13.11 in association with the 31 chemicals
listed by the ANSI/ASHRAE Standard. This approach addresses residential
buildings, small businesses, and schools as well as all office buildings. As
for off-gassing chemicals from carpeting, California has set forth limits that
allegedly exceed that of the Green Label Plus limits. See Table 13.11.
GREENGUARD Environmental Institute has taken the California protocols and limits and expanded on them. GREENGUARD has deferred to the
California CRELs and included all the more than 400 substances listed on
the ACGIH list of toxic chemicals. For substances not listed with a CREL,
GREENGUARD guidelines uses 1/100th the ACGIH occupational exposure
standards as limits in the predicted air concentrations for the designated
indoor air environment.
However, GREENGUARD varies slightly from the others in providing
maximum allowable “long-term” emissions limits for phthalates, respirable
particles, and ozone (see Table 13.12).
GREENGUARD certifies Green Label carpeting/pads and Blue Angel electronics equipment and copy/printer machines.
Summary
Going green is going lean! As man spends 90 percent or more of his time
indoors and buildings become more energy efficient, humanity is under
assault from a multitude of chemicals. The response is to minimize exposures by the proactive approach of product emissions testing. Chamber
Benzene—0.002
Styrene—0.04
Benzene—0.002
Styrene—0.08
0.4
0.22
0.4
Benzene—0.002
Styrene— 0.04
1/10 TLV
Benzene—0.002
Styrene—0.08
1/10 TLV
1/10 STEL/Cc
1/100 TLVd
5
0.22
0.22
1/100 TLV
½ CA Chronic REL
1/100 TLV
–500
–
250
Individual
VOC TLV (mg/
m3)
0.05 mg/m3
0.05 mg/m3
–
–
0.04 ppm
0.013 ppm
25 ppb
13.5 ppbb
13.5 ppb
Formaldehyde
–
–
–
–
–
–
50 ppb
–
43 ppb
Total
Aldehydes
–
–
–
–
–
0.01 mg/m3
–
0.01 mg/m3
Total
Phthalates
Note: Respirable = PM 10; minimum seven days with no preconditioning.
a Defined to be the total response of measured VOCs falling within the C5–C18 range, with responses calibrated to a toluene surrogate.
b The California Chronic REL for formaldehyde is 9 ppb.
c Less than 1/10 STEL/C corresponding to the ACGIH TLV and AIHA WEEL (or less than the TWA if no STEL/C).
d Less than 1/100 the TWA corresponding to the ACGIH TLV and AIHA WEEL.
Color
Greenguard Only
Monochrome
Color
Building Materials, Furnishings,
and Finishes
Greenguard Certification
Schools: Greenguard and California
Standard
Schools: Greenguard Only
Electronics
Greenguard
short term (acute)
long term (chronic)
Office Equipment
Greenguard and Blue Angel
Monochrome
Total
VOCa
(µg/m3)
Greenguard Maximum Allowable Emissions
TABLE 13.12
total—0.16
respirable—0.015
total—0.16
respirable—0.015
total—0.16
total—0.16
–
respirable— 0.035
respirable—0.05
–
respirable—0.02
Particulates
mg/m3
0.03 ppm
0.03 ppm
0.03 ppm
0.03
–
0.05
–
–
Ozone
(ppm)
224
Indoor Air Quality: The Latest Sampling of Analytical Methods
Product Emissions
225
testing methods are being refined, and the maximum acceptable limits seem
to be in a constant state of motion.
The end game is, through computer modeling, to predict exposures to
indoor air environments, whereby many of the “sick building syndrome”
complaints can be better managed upfront. The cost can be hefty for the certifications and special emissions chamber testing of furnishings, but the cost
at the other end can be occupant dissatisfaction, extensive environmental
consultant costs, and low morale.
Predicted air concentrations are based on ideal air movement and exchange
rates in office environments. Ideal is often disconnected from reality. Proceed
with a healthy dose of reserved skepticism!
References
1. Global Ecolabelling Network. What is Ecolabelling? (2008). Viewed on March 26,
2010, at http://www.globallabelling.net/whatis.html
2. Franke, D., et al. Furnishings and the Indoor Environment. Air Quality Sciences,
Inc., Atlanta, Georgia (1995).
3. Haneke, K.E. Review of Toxicological Literature—4-Phenylcyclohexene. Research
Triangle Park, North Carolina (July 2002).
4. Schleibinger, H., K. Fitzner, et al. Chemical analysis and sensory evaluation
of indoor air by a thermal desportion/GC/FID/sniffer method. Gefahrstoffe
Reinhalt Luft. 61:11–12 (2001), pp. 528–531.
5. Schleibinger, H., K. Fitzner, et al. VOC-concentrations in Berlin indoor environments between 1988 and 1999. Gefahrstoffe Reinhalt Luft. 61:1–2 (2001), pp.
26–38.
6. Molhave, L. Irritancy of Volatile Organic Compounds in Indoor Air Quality. Paper
presented at the Fifth International Conference on Indoor Air Quality and
Climate in Toronto, Canada (1990).
7. California Department of Health Services. Standard Practice for the Testing of
Volatile Organic Emissions from Various Sources Using Small-Scale Environmental
Chambers (July 15, 2004).
8. Ibid., p. 14.
9. American Standard and Testing Materials. Standard Guide for Small-Scale
Environmental Chamber Determinations of Organic Emissions from Indoor Materials/
Products. ASTM D5116-90 (1990).
10. Air Quality Sciences. Standard Method for Measuring and Evaluating Chemical
Emissions from Building Materials, Finishes and Furnishings Using Dynamic
Environmental Chambers. GREENGUARD Environmental Institute, Marietta,
Georgia (2008).
11. Air Quality Sciences. Standard Method for Measuring and Evaluating Chemical
and Particle Emissions from Office Equipment (Hardcopy Devices) Using Dynamic
Environmental Chambers. GREENGUARD Environmental Institute, Marietta,
Georgia (2009).
226
Indoor Air Quality: The Latest Sampling of Analytical Methods
12. Air Quality Sciences. Standard Method for Measuring and Evaluating Chemical
and Particle Emissions from Electronic Equipment Using Dynamic Environmental
Chambers. GREENGUARD Environmental Institute, Marietta, Georgia (2009).
13. Air Quality Sciences. Defining Product Emission Measurements (Bulletin). Air
Quality Sciences, Inc., Atlanta, Georgia (1995).
14. Air Quality Sciences. Standard Method for Measuring and Evaluating Chemical
Emissions from Building Materials, Finishes and Furnishings Using Dynamic
Environmental Chambers—Table 6.4 Parameters to Be Used for Calculation of VOC
Concentrations. GREENGUARD Environmental Institute, Marietta, Georgia
(2008), p. 48.
15. Black, M., D. Franke, and C. Northeim. Furnishings and the Indoor Environment.
Journal of the Textile Institute (1994), pp. 496–504.
Section IV
Identification of Dusts
14
Forensics of Dust
Since as early as the late 1800s, scientists have used forensic nucroscopy
in crime detection. Pollen typing has been used to determine the source
areas for illegal shipments of marijuana. Crime scene soil samples have
been used to locate the source of the material. Clothing fibers are traced by
fiber type and special dyes. Hair can be differentiated as to species (e.g.,
human, dog, or cat) and distinct color, texture, and thickness. Dust found at
a crime scene sometimes contains evidence as to an association with certain
industrial activities.
Only recently has forensic microscopy been recognized as a tool in indoor
air quality investigations. Without forensic microscopy, identification of
unknowns was limited. The investigator would develop a theory as to the
dust component that caused health problems and test the theory. Not only
was this time-consuming and expensive, but the actual causative agent was
often overlooked.
If building occupants complained of allergy symptoms, an investigator
automatically assumed the problem was molds. Even when sample results
did not support the theory, the investigator may persist and state that the
sampling methods are faulty. This scenario often culminates in an extensive search for the ubiquitous mold and, in many cases, destruction of walls
and flooring in the frantic search for the hidden demon. If one looks hard
enough, behind enough walls and enclosures, an investigator will eventually locate molds.
With forensic microscopy, the allergenic dust in an occupied space can be
characterized. Not only can pollen, mold spores, algae, and insect parts be
identified, but an experienced microscopist can characterize rodent, bat, cat,
and dog hairs as well. The microscopist can also quantify the population
density as normal or excessive. For instance, the microscopist may identify
excessive amounts of rodent hairs. When pressed for more information, the
microscopist may come back with, “More than normally observed in occupied spaces, typical of rodent infested barns.”
Forensic microscopy has also been used to identify other components of
dust that may cause nonallergy health problems. For instance, chemicals
adsorbed onto the surface of particles may be identified (e.g., formaldehyde
on dust particles). Pharmaceutical dust can be identified from previous
manufacturing facilities (e.g., amphetamines). Fibers that may cause lung
irritation (e.g., treated glass fibers) or long-term health effects (e.g., asbestos)
229
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Indoor Air Quality: The Latest Sampling of Analytical Methods
can be identified. Toxic minerals (e.g., silica) and paint components (e.g., lead
chromate and fungicides) can be identified.
Suspect materials may be either confirmed or denied. For instance, in one
case, white spots on surfaces implicated paint as the source of indoor air
quality, yet the spots were silicon.
Forensic microscopy can be used as a tool in identifying particles and
chemicals. The list goes on!
Occurrences of Forensic Dust
In 1972, The McCrone Institute performed a study to determine settling rates
of dust on surfaces. They found that nearly 1,000 particles per one square
centimeter settled hourly. The particles were all in excess of 5 microns in size.
The calculated settling rate for dust was thus found to be 24,000 particles per
square centimeter per day. Typical dust in indoor air quality was also found
to consist of human epidermal cells, plant pollen, human/animal hairs,
textile fibers, paper fibers, minerals (from outdoor soils and dust brought
indoors), and a host of other materials that may typify a given environment
(e.g., fly ash from the gas burning furnace in the building).1
A study by Cornell University suggested that indoor air quality problems
were caused by glass fibers.2 Possible sources of airborne glass fiber exposures include, but are not limited to, fireproofing in air plenums, ceiling tiles,
duct board, and furnace filter material. For a few photographic examples of
different source glass fibers, see Figure 14.1.
One example of glass fibers in indoor air quality involves a residential occupant. A woman complained of a home-related itch. Her doctor speculated
the probable cause was glass fibers. Subsequently, settled dust samples were
collected from various areas around the house, and bulk samples were taken
of various building/furnishing materials known to have fibers. Each of the
settled dust samples was found to contain large amounts of glass fibers that
were impregnated and covered with globules of a pink resin. None of the bulk
glass fiber samples matched. The investigator returned for additional samples
and tracked down insulation (e.g., batting) in the enclosed wall spaces that
had the same appearance as the settled fibers in the dust. Thus, the insulation
was the confirmed culprit. Upon further investigation, the means by which
the enclosed insulation entered into the occupied space was determined. The
air movement caused by leaking air ducts disturbed the surface of the interior insulation and picked up the fibers, distributing them throughout the
residence through the air supply vents.
Some people say they are allergic to dust, but dust varies in composition.
There is a considerable difference between barnyard dust verses dust in a
conditioned building. It is the composition that causes health problems, not
Forensics of Dust
231
FIGURE 14.1
Photomicrographs of glass fibers from different sources, magnified 400x. They include: (top
left) untreated fiberglass; (top right) duct board; (bottom left) duct board with coating material
treated using xylene and sulfuric acid to affect a color change that tags free aldehydes; and
(bottom right) thermal insulation with asphalt impregnated binder.
the dust itself. For a generalized listing of dust components and some representative photomicrographs, see Table 14.1 and Figure 14.2.
It should also be noted that dust composition is in a constant state of flux,
even in conditioned office spaces where there are no internal sources of
dust (e.g., molds growing, cockroaches, and rodents). People bring in dust
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Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 14.1
Characterization of Dust Components in Indoor
Environments
Biological
Pollen
Fungal and bacterial spores
Algae
Insect parts
Skin cells
Fibers
Hair (e.g., human, cat, or dog hair)
Clothes fibers
Paper fibers
Spun fibers (e.g., glass fibers)
Mineral fibers (e.g., asbestos)
Wood (hardwood versus soft wood)
Plant fibers (e.g., seed hairs, blast/leaf/grass fibers)
Miscellaneous (e.g., carbon fibers, feathers, spider webs, etc.)
Minerals
Soils
Amorphous versus crystalline
Others
Soot and ash
Metal fumes
Paint
Explosives
Pharmaceuticals
Drugs
Source: Excerpted from Forensic Microscopy4
on their clothing, shoes, and body surfaces. They bring components of dust
from the environments they live, shop, and play in. Yet it is unreasonable
not to anticipate internal sources as well. With consideration for all possible
sources, one dust sample may have several allergens and other components
that may cause nonallergen health problems. Thus an investigator should be
open to all possibilities.
Sampling Methodologies 5, 6
Although there are a few published approaches, most procedures should
be worked out between the analytical laboratory and the indoor air quality
investigator. Yet keep in mind, methods appear simple but if not completely
Forensics of Dust
233
FIGURE 14.2
Photomicrographs of identified dust component, magnified 400x. They are epithelial cells (top
left), an insect leg (top right), hair fibers (middle left), clothing fibers (middle right), crystalline
mineral formations (bottom left), and a general overview of environmental dust (bottom right).
The latter shows minerals, spores, wood fibers, pollen, and plant hair.
thought out, these simple methodologies can be misconstrued or misinterpretation. Plan a strategy and stick to it. If disallowed access, don’t take a
sample just to take a sample.
For example, an investigator was attempting to recreate dust exposures
that occurred two years prior to sample collection. This was a litigious case
whereby the defense attorneys would only allow the investigator to take
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Indoor Air Quality: The Latest Sampling of Analytical Methods
carpet and dust samples from under old filing cabinets. The defense attorneys refused to permit dust collection from above ceiling tiles. So the investigator took samples from locations where he was permitted to sample (e.g.,
under the filing cabinet). The forensic samples predictably disclosed minimal dust. In this situation, the investigator wasted time and money sampling
only where he was permitted access, not where good judgment dictated that
the sample be taken.
Consider when and where the sample should be taken. For historic surface dust that has settled over an extended period of time, the investigator
should consider areas that frequently get overlooked during cleaning (e.g.,
ledges above doors, window frames, picture frames, above ceiling tiles, and
air supply/return vents). Carpets and upholstery generally retain dust over
the passage of years, and if a picture of the past is required, such as in litigation, dust from under the carpet (e.g., bulk sample) or within the upholstery
(e.g., micro-vacuum sample) should be collected.
For a more recent settled dust sample, the investigator may want to determine the last time an area was cleaned, record the date/time, and take a
sample in an area that has been cleaned. If an area has not been confirmed as
having been cleaned, assume it has not. Areas that typically get missed are
tops of computers, bookshelves, lamps, and memorabilia.
For airborne dust, the investigator has several means for taking air samples. Air samples would represent dust components and levels that the occupant was breathing during the sampling period.
Methods herein are provided for settled surface dust sampling, airborne
dust sampling, bulk sampling, and textile/carpet sampling. Choose the
method that is most appropriate to a given situation.
Settled Surface Dust Sampling
Settled dust may be collected from smooth surfaces (e.g., desktops) and
rough surfaces (e.g., carpeting) by any number of techniques. Some require
specialty supplies. Others require the use of that which is readily available
at a local retail store.
Specialty Tape
Specialty tape may be purchased from microscope supply venders. The
tacky material is minimal and does not hold the collected material such that
it becomes difficult or impossible to remove. The taped material is retained
by affixing the tacky surface to a clean surface and placing it into a fiber free
envelope/plastic bag for transport to the laboratory. At the laboratory, the
microscopist will “pluck” the material from the surface of the tape by using
a special micromanipulation device (e.g., fine tungsten needles with a tip
measuring 1 to 10 microns in diameter). With this technique, the dust components may be isolated and identified individually.
Forensics of Dust
235
Clear Tape
A clear tape (e.g., 3M Crystal Clear) is available in some office supply stores.
This tape is not the usual tape that one can see through when it is affixed
to paper. It is a clear tape where the writing on the carrier is readable. The
tape is touched to a surface, and dust particles adhere to the sticky portion
of the tape. This is then placed immediately onto a microscope slide with or
without a stain.
The drawback to this method is that once affixed to the slide, the collected
sample cannot be further manipulated and stained without great difficulty
(e.g., treating the surface of the tape with a solvent). Then, too, if there is
excessive material on the tape to reasonably distinguish individual particles,
the sample may again require special processing. With these limitations in
mind, the environmental professional may choose to use this technique only
for screening and gross examination of material or for confirming the presence of a suspect material for which the microscope slide has already been
treated with the appropriate stain.
However, if the investigator should choose to use the clear tape, there are
means available to manage the otherwise irretrievable sample. The particles
that have adhered to the tape may be removed by lifting the tape, applying
a small drop of benzene, and using a fine needle to make a small ball of
the adhesive trapped particle(s).6 The trapped material can be withdrawn
and the ball of adhesive removed chemically. This process is tedious and
choice of a more easily manipulated collection media is desired whenever
feasible.
Post-it Paper7
Post-it paper is excellent for sample collection as it is easily obtained and
inexpensive. The sticky surface of a Post-it is pressed onto the settled dust,
the paper folded into itself (with the sticky portion inside), and shipped to
the laboratory of choice in a plastic zip-lock bag. Analysis may be performed
by particle picking material from the sticky surface or by scanning electron
microscope while the particles are still on the paper.
Micro-vacuuming8
Micro-vacuuming has been receiving a considerable amount of attention,
particularly for asbestos contaminated settled dust. A vacuum pump is used
to collect dust particulate within a 100 square centimeter surface at a recommended flow rate of 2.0 liters per minute. This method is particularly useful
in dust collection from irregular surfaces (e.g., carpeting).
The detection limit of this methodology is 150,000 structures per square
foot [or 161 structures per square centimeter (structures/sq cm)] as determined by transmission electron microscopy (TEM). Concentrations over
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Indoor Air Quality: The Latest Sampling of Analytical Methods
1,000 structures/sq cm are considered elevated, while levels over 100,000
were used to indicate an abatement project barrier has been breached. There
are no regulations that provide acceptable/nonacceptable limits.
Airborne Dust Sampling
Airborne dust capture may be preferred over settled dust collection in order to
determine the existing suspended particulates (not the existing and previously
deposited) and to collect some of the smaller particles that may not have settled
due to the size or shape. For example, particles less than 2.5 microns (e.g., PM 2.5)
would tend not to settle and would best be collected through air sampling.
Spore Trap
A spore trap consists of a treated microscope slide that is contained within a
cassette. The slide is treated with a sticky substance onto which mold spores,
pollen, insect parts and pieces, skin fragments, hairs, and fibers will adhere
upon impaction onto its surface. Its most common use has been sampling for
nonviable mold spores, mold fragments, and pollen.
The end seals on the cassette are removed, and the cassette is connected
by flexible tubing and a 1/2-inch to 1/4-inch converter to an air sampling
pump. The pump flow rate is calibrated. Air is sampled for an abbreviated
period of time, cassettes are resealed, and samples are sent to a laboratory
for analysis.
A summary approach is as follows:
•
•
•
•
Equipment: air sampling pump
Collection medium: Air-O-Cell cassette
Flow rate: 15 liters/minute
Recommended sample duration: 1 to 10 minutes, based on anticipated loading
Collection medium loading is based on perceived environmental conditions
and anticipated airborne spores, based on professional experience. Where
excessive loading occurs on the slide, enumeration becomes difficult if not
impossible. In the latter case, samples may be significantly underestimated
and difficult to identify.
In clean office environments and outside where there is very little dust
anticipated, sampling should be performed for 10 minutes. In dusty areas
and areas where there is considerable renovation, a 1 minute sample
should be considered. Indoor air environments where there is moderate dust or where considerable levels of mold spores (e.g., greater than
500 spores) are anticipated, the sampling duration should be reduced
Forensics of Dust
237
accordingly (e.g., 6 to 8 minutes). Experience will be the investigators best
guide.
Membrane Filters
Air sampling may be performed for suspended dust by using a membrane
filter that is contained within a cassette and an air sampling pump. This is
a dry sampling method and will desiccate, damage the more fragile components in dust.
A summary approach is as follows:
•
•
•
•
Equipment: air sampling pump
Collection media: cassette containing a filter
Flow rate: 1 to 15 liters/minute
Recommended sample duration: 100 minutes (i.e., fragile biologicals),
135 minutes (i.e., high flow rate collection of nonfragile material) to
2000 minutes (i.e., low flow rate of nonfragile material)
• Recommended air volume: 100 to 2000 liters
Recommended filter types include, but are not limited to, the following:
• Polycarbonate filter—Using a stereomicroscope, the microscopist
may selectively isolate and pluck material from the surface of the
filter.
• Fiberglass filter—The microscopist may slice the filter and look at
the material through an unspecialized microscope (e.g., not a phase
contrast microscope) that will allow a view of the material on the
surface of the fiberglass while the light passes through the thinnedout fibrous backing.
• Mixed cellulose ester filter—The microscopist may melt the filter
(in a procedure similar to that of asbestos air sample filter analysis)
using vaporized acetone. This method is not recommended in most
cases where desiccation or destruction of the sought after material
may occur. If the material is an unknown, this approach will disallow identification of content.
Keep in mind that each of the above filters has different pore sizes, depending upon the manufacturer and the various specifications. One filter type
may come with several choices as to pore size or particle retention capabilities. The smaller the pore size, the more expensive the filter. Be certain
to obtain one that will capture particulates down to 1 micron in diameter or
better. All of the above-mentioned filters can be purchased with a minimum
of 1 micron and down to better than 0.025 microns.8 If electron microscopy is
to be performed, the latter is unnecessary.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
The air sampling flow rate should be adjusted to produce as large a sample
volume as possible within the time period desired while keeping the upper
limit within a flow that will not cause damage to the filter or desiccate biological material (e.g., mold spores and bacteria). Although 15 liters per minute will not damage most filters, a flow rate of 1 liter per minute or less is not
likely to dry biological components in airborne dust.
Larger air volumes provide more representative samples. Although total
sampled air volumes have been as low as 100 liters, a collection of 2000 liters
may prove more valuable. Then, too, the biological material stands a greater
chance of being damaged with longer sample durations. So the environmental professional may choose to take a minimum of two samples per
site where he/she suspects airborne biological dust. A low flow, low sample
volume will allow collection of the more fragile biological components, and
a high flow, high volume will permit greater detection. If components of the
high volume sample fail to reflect biological components of the low volume
sample, the high flow, high volume sample is likely to have caused damage to the more fragile biological component. Otherwise, a high flow, high
volume sample provides more sample material. A dump truck of sample is
better than a thimble!
Even if the microscopist is not intending to quantify the results in particle
per cubic meter, air volumes should be recorded in the off-chance that the
volume may be used later (e.g., where asbestos fibers are identified, the airborne fiber counts may be determined). The air volume, however, will rarely
be relevant to the forensic microscopist.
Cascade Impactors
An adhesive film may be placed on the surface of each stage of an impactor,
and the sample collection time may be limited while separating the collected
material by size. As the particles tend to impact singularly, the microscopist may analyze each adhesive film directly. Separation and isolation are
already completed by this sampling method.
A summary approach is as follows:
•
•
•
•
Equipment: air sampling pump
Collection media: cascade impactor with special adhesive film
Flow rate: 28.4 liters/minute
Recommended sample duration: 5 to 10 minutes
Other Methods
Other air sampling techniques that have been used include impingers and
cyclones. Processing these samples may be more involved (e.g., time-consuming
and expensive), yet impinger and cyclone samples allow for dilution and
Forensics of Dust
239
separation of the collected material. They are, however, limited in their ability
to collect only certain particle sizes. The impinger collects particles greater
than 1 micron in diameter, those that are visible under the light microscope.
On the other hand, the cyclone collects nonfibrous particles of less than
5 microns. Anything greater than 5 microns or fibrous in nature is likely to be
overlooked.
Bulk Sampling
An alternative to the specialty tape and problems associated with the clear
tape is “bulk dust” sampling. When dealing with large deposits of dust (or
dirt), bulk sampling becomes the most feasible approach. Define an area
where the collection is indicated and scoop/scrape the dust from the surface,
using a fiber-free (e.g., a cellophane envelope), contaminant-free scraper (e.g.,
a stainless-steel spatula). At the laboratory, large samples are homogenized,
and a representative sampling of the entire mix will be extracted. So when
deciding how much to collect, the environmental professional may wish to
restrict sample sites and limit collection to clearly defined, distinct areas.
For instance, a specific air supply louver in a complaint area and settled dust
from a recently cleaned table surface are clearly defined, delineated sample
locations.
Then, too, a building material or structural component may appear to be
contaminated with an unidentified substance that has become part of its substrate. For instance, a weakened spot on a steel beam may be associated with
an unidentified material, or gypsum board may have what appears to be a
microbial growth. If possible, collect a piece (e.g., at least a 4-inch square surface) of the substrate. Place it in a plastic baggie and ship with instructions to
the lab that you wish to know what the associated material is and describe its
physical appearance as best you can. If the instructions are incomplete, the
laboratory might just miss the point of the request. Be clear and concise in
your instructions!
Textile/Carpet Sampling 9
Micro-vacuuming of textiles and carpeting has proven inferior to direct
extraction and sonication of textiles and carpeting. A comparative study was
performed of asbestos contamination of carpets that demonstrated the difference between the two methods. See Table 14.2.
Textile/carpet sampling involves cutting a piece from the textile/carpet
a minimum of 100 square centimeters in size. This is placed in a widemouth polyethylene jar or zip-lock bag. At the laboratory, the sought after
substance is extracted, suspended in water, and filtered through a polycarbonate filter or cellulose ester filter for analysis by transmission electron
microscopy. This method is primarily used for asbestos analysis in carpet
samples.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 14.2
Comparative Sampling Approaches for Asbestos‑Contaminated
Carpet Analyses
Sample Number
1
2
3
4
5
6
7
8
Carpet Piece
Microvac
4,800,000
3,300,000
<5,400
3,800,000
3,000,000
2,500,000
3,600,000
4,700,000
21,000
30,000
<350
74,000
50,000
95,000
18,000
35,000
Source: Millette, J.R., et al. Environmental Choices Technical Supplement
(March/April 1993).
Note: < = Indicates the limit of detection for the method used.
Analytical Methodologies
Depending on experience and equipment, the microscopist has the ability to detect, identify, and measure trace quantities of a substance down
to the elemental composition and structural configuration of molecules.
Most particles larger than 1 micron in size can be identified by visible
light microscope analysis. On the low end of sizing are some bacteria
(e.g., 1 micron), many molds (e.g., 1 to 10 microns), and actinomycetes (e.g.,
1 to 5 microns). On the high end are some molds (e.g., up to 50 microns in
size), fibers (e.g., in excess of 100 microns in length), and hair (e.g., 10 to in
excess of 100 microns in length). Then, too, particles may carry chemicals
on their surfaces (e.g., formaldehyde adsorbed onto the surface of dust).
These, too, may be identified.
Particles that are 1 micron or less are more difficult, if not impossible, to see
by visible light microscope analyses. Under these conditions, special microanalytical procedures may solve the dilemma and confirm suspect materials. Forensic microscopy is only limited by the skills and experience of the
microscopist. Some of the methods used are mentioned herein.
Visible Light Microscopy
An experienced microscopist may identify most, not all, sample particulates (greater than 1 micron in size) in a few seconds, if not immediately,
without altering the chemical and physical properties of the material. Like
differentiating a tree from a light post, when seen and identified on a frequent basis, most microscopic material is easily identified.
Forensics of Dust
241
Visible Light Microscopy: Identification of particles
greater than 1 micron in size
Parameters that are used in the microscopic analyses include, but are not
limited to, the following:
•
•
•
•
•
•
•
•
•
•
•
•
Size
Shape
Color
Homogeneity
Transparency
Magnetic qualities
Elasticity
Specific gravity
Refractive indices
Birefringence
Extinction
Dispersion staining
Sample particles (larger than 1 micron in size) are identified with minimal
effort by visible light microscopy. This is done through differences in size,
shape, homogeneity, color, transparency, magnetic qualities, and specific
gravity. Again, on occasion, additional information is necessary for positive
identification of suspect material or for identification of a substance that is
unfamiliar to the microscopist.
The remaining parameters are ascertained through the use of polarized
light microscopy, which greatly increases particle characterization and competence. It also ensures positive identification of types of fibers, minerals,
and some industrial pollutants.
Specialized Microscopic Techniques
Specialized techniques are available for use when the particle size is less
than 1 micron, when the price is not a consideration, or for confirmation in
litigation or high visibility cases. Occasionally, other techniques become necessary when dealing with extremely small particles or exotic mixtures.
X-Ray Diffraction11
Other than visible light microscopy, x-ray diffraction is the only other technique available that permits identification and differentiation of crystals.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Where there are three different forms of silica (i.e., quartz, tridymite, and
cristobalite), chemical analysis may confirm the presence of silica but not be
able to differentiate the type.
The sensitivity is down to approximately 10 –2 nanograms, and the procedure is nondestructive of the sample. Although it may be as small as one
particle, measuring 5 microns in diameter, the ideal sample size is 40 to
50 microns. The smaller particles require more extensive manipulation (e.g.,
removal of air from within the camera), so the cost for analysis may increase
with smaller particle sizes.
X-ray diffraction measures the interplanar spacing of atoms in a crystal.
Spacing is unique for every compound, and each is identified by comparison
with known compounds. This comparison is performed with the assistance of a
computer file that has well over 20,000 substances in its data bank. The data file
is constantly being expanded. If a sample is suspect of containing a specific substance that is not on file, the known substance (in its pure form) may be scanned
and entered into the data banks to be used as a reference for the unknown.
Scanning Electron Microscope12
Scanning electron microscopy (SEM) comes into play where a sample size
is too small to be observed by visible light microscopy (equal to or less than
1 micron in diameter) or where greater resolution and depth of field of larger
particles (from 1 to 100 microns in diameter) is required. It operates in a
similar fashion to that of the stereo binocular microscope, refracting electron
beams (instead of visible light) off the surface of a sample. These refracted
electrons are projected onto a viewing camera or film to permit the analyst
to observe the structure(s).
Scanning Electron Microscopy:
morphology, spacial, and inorganic elemental
analysis of particles down to 0.2 micron in size
The SEM is capable of magnification of particles typically around 0.2 micron
in diameter. Where the depth of field for visible light microscopy is around
1 micron, it is 300 microns for the SEM. This allows for greater contrast and
ease of viewing the unknown sample.
The resolution is about 300,000 times the actual particle size, or 200 times
greater than that of the most powerful light microscope (which has a magnification capability of 1500 times). Smaller particles are more readily observed
due to the increased magnification. This is generally the case with metal
fumes, clays, some pigments, bacteria, and viruses.
Another added feature to the SEM is the ability to add an energy dispersive
x-ray analyzer (EDXRA) to the unit. This x-ray analyzer is capable of greater
Forensics of Dust
243
detection than that of x-ray diffraction. Where the x-ray diffraction provides
a means for identifying compounds, the EDXRA can detect elements (above
nitrogen on the periodic table). Most analysts agree that without this added
ability for detecting elements SEM would be inferior to visible light microscopy in its detection ability.
Still spores, bacteria, and viruses can be identified as spores, bacteria, and
viruses only. Viruses and bacteria are generally smaller than 1 micron in
diameter and can be identified as such only through the use of SEM due to
the higher resolution. To type these biological components by genus and species, the sample must still be cultured or manipulated in some other fashion
besides microscopy.
Particles greater than 1 micron in diameter may still require the EDXRA
for identification and are frequently more easily identified by visible light
microscopy. Thus SEM with EDXRA may be used as a secondary means of
identification for the larger particles, and as the primary means of analysis
for particles at or less than 1 micron in diameter.
Transmission Electron Microscope13
Transmission electron microscopy (TEM) analysis works in a similar fashion
to that of the biological microscope by penetrating a sample with focused
electron beams instead of visible light. These electron beams are observed in
a similar fashion to that of SEM where the beams are projected onto a viewing screen or film.
Transmission Electron Microscopy:
identification and product analysis of particles/
components down to 0.5 x 103 microns in size
The depth of focus is 1 micron and its resolution is 0.5 × 103 micron. The
maximum prepared particle thickness is 0.05 micron, and the maximum
sample diameter is 3 millimeters. The TEM can be fitted for selected area
electron diffraction (SAED) and EDXRA. The SAED functions in a similar
fashion to that of x-ray diffraction, limiting the coverage area, and the electron beam is used to measure the interplanar spacing of atoms in a given
area. The SAED information is compared with a data bank for compound
identification, and the EDXRA provides the elemental fingerprint.
Particles are scanned for structural appearance, compound identification,
and elemental fingerprinting. If a search is performed for a specific substance,
the microscopist reports results in percent by weight. It is important to note
that where asbestos content is performed by polarized light microscopy, the
results are provided as percent by volume where the definition of asbestos is
a mixture containing greater than 1 percent by weight of certain types. The
only means available to provide true percent by weight is through TEM.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Electron Microprobe Analyzer14
The electron microprobe analyzer (EMA) is an ultra micro analytical tool
that can be used to enhance a light microscope, SEM, x-ray fluorescence, and
cathode luminescence. It is also referred to as mass scanning.
A sample containing a large number of small particles may be rapidly
characterized by chemical composition. This is generally performed by automation of the specimen stage, scanning beam, and spectrometer. In this case,
a few thousand particles can be characterized from any given sample.
The electron microprobe analyzer may be used to locate a needle in a haystack. If searching for a known substance that may be present in a sample in
only parts per million, or trace levels (e.g., asbestos fibers in urban air), the
analyzer is ideal. It is set up to identify an element, or combination of elements, that are present in the substance of concern. Each time the substance
is located, the stage stops, and that particle is quantitatively analyzed. Then
the stage continues its search. The ideal lower limit for adequate identification is 0.1 percent, but the method is capable of locating down to 10–4 percent.
The latter involves a considerable amount of time consumption, therefore
cost, but it is possible.
Elemental analysis is possible of samples as small as 1 micron in diameter
and as minimal as 1 percent of a sample. This constitutes a detection limit as
low as 10–4 nanograms. An electron beam is focused to a spot smaller than
1 microns square in area. The characteristic x-rays emitted from the spot are
analyzed for wavelength, or energy, dispersing systems both quantitatively
and qualitatively. A limitation is its inability to detect lithium (sometimes
beryllium), and 100 parts per million is the lower limit of detection for most
elements.
The analyzer is capable of mass scanning of between 4 and 50 particles per
hour. The speed and ease of analysis allows for any given sample, containing
up to 1000 unknowns, as little as 20 hours to analyze a 24-hour turnaround,
in a pinch!
Ion Microprobe Analyzer15
The ion microprobe analyzer (IMA) provides a means for mass spectrometry on small particles or small areas of bulk samples. This method is one of
the most sensitive tools available for small particle analysis. It is sensitive to
every element in the periodic table and can, under ideal conditions, detect
as little as 10 –20 grams of some elements, and 10 –19 grams of most elements.
It is fully capable of analysis of trace amounts of material from samples as
small as 1 micron and, in some instances, can obtain parts per billion of
some elements. The time required for semiquantitative analysis is typically
40 seconds, or as short as 4 seconds.
Forensics of Dust
245
The instrumentation consists of a light microscope (which is used to
locate the sample), an ion source, a column of two electrostatic lenses, and
a mass spectrometer.
The versatility of the IMA is similar to that of the electron microprobe analyzer, yet it is much faster and can assess particles that are much smaller (e.g.,
1 part per billion instead of 1 part per million). Any airborne, waterborne,
or contaminant particles can be analyzed with this tool. A few examples
include the analysis of micrometeorites, lead particles from auto exhaust,
and contaminants on integrated circuits.
Commercial Laboratories
Due to the extensive training required to be proficient in all aspects of this
field, there are a limited number of laboratories capable of responding to all
the nuances that may arise in an environmental evaluation. An experienced
microscopist may cost a little more per hour yet be able to provide results
with less time expenditure than one with less experience and lower rates.
On the other hand, the desired information may be obvious (e.g., heavy
concentrations of ragweed pollen) and readily apparent to even the inexperienced microscopist who may serve as an initial previewer. Many of the commercial laboratories are accustomed to analyzing primarily for asbestos only.
Query the commercial laboratory as to its capabilities and limitations. Those
experienced in performing forensic analyses can easily apply the forensic
knowledge to environmental issues.
Charging only a nominal fee to perform a more complete analysis, some
mold/spore laboratories provide results in terms of total fibers. A forensic
laboratory should be able to identify each of the fibers (e.g., rodent hairs,
fiberglass, cellulose) and much more.
Summary
In conjunction with an experienced laboratory, forensic dust sampling is a
very powerful tool for identifying a broad range of unknowns. Not only can
those substances that are more commonly encountered be identified, but
forensic microscopy provides an avenue for identifying unknowns where
there are no traditional methodologies or no readily available means for
analysis. Not only can particles be identified, but many metals and chemicals
can be identified. This approach to indoor air quality takes the investigator
to a new dimension in sampling methodologies.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
References
1. McCrone, W.C. Detection and Measurement with the Microscope. American
Laboratory. (Reprint) (December 1972).
2. Hedge, A., W. Erickson, and G. Rubin. Effects of Man Made Mineral Fibers in
Settled Dust on Sick Building Syndrome in Air Conditioned Offices. Proceedings
from a Conference on Indoor Air (1993).
3. McCrone, W.C. The Solids We Breathe. Industrial Research. (April 1977).
4. Bisbing, R. Clues in the Dust. American Laboratory. (Reprint) (November 1989).
5. McCrone, W.C. Microscopy and Pollution Analysis. Reprint from Measuring,
Monitoring, and Surveillance of Air Pollution, Air Pollution. Vol. 111 (1976).
6. McCrone, W.C. Air Pollution, 3rd ed. Academic Press, Inc., New York, Vol. 111
(1976), pp. 101–2.
7. Bisbing, R.E. Microscope and Pollution Analysis. (Oral communication) McCrone
Associates, Inc., Chicago (June 1995).
8. Millette, J.R., T. Kremer, and R.Wheeles. Settled Dust Analysis Used in Assessment
of Buildings Containing Asbestos. (Bulletin) McCrone Environmental Services,
Inc., Norcross, Georgia (1990), pp. 216–19.
9. Millipore Product Literature. Millipore Corporation, Bedford, Massachusetts
(1996).
10. Millette, J.R., et al. Methods for the Analysis of Carpet Samples for Asbestos.
Environmental Choices Technical Supplement (March/April 1993).
11. McCrone, W.C. Air Pollution, 3rd ed. Academic Press, Inc., New York Vol. III
(1976), pp. 114–15.
12. Ibid., pp. 118–21.
13. Ibid., pp. 121–32.
14. Ibid. pp.132–38.
15. Ibid. pp.138 –43.
15
Animal Allergenic Dust
The neglected partner in allergenic complicity with pollen and mold spores
is animal allergens, or house dust. Only within the past 10 years have clinical studies revealed a strong relationship between levels of animal allergens
in dust and allergy symptoms. Technology has evolved. Methods have been
refined, and immunoassay technology comes into the limelight.
Detection and quantitation of a wide range of antigenic biological and
nonbiological substances are now possible through immunoassay analytical methods. Allergenic substances that are processed include proteins, glycoproteins, hormones, peptides, chemical haptens, and drugs. Of particular
interest to the environmental professional, researchers have developed
immunoassays for animal allergens, predominantly those derived from
mites, cats, cockroaches, and rodents. Methods have also been developed for
certain species of fungi (e.g., Aspergillus flavis) and for latex.
An immunoassay involves identification of the antigens by creating antibodies for the express purpose of tagging specific materials. Quantitation is
based on the antibody antigen complexes. Thus inununoassay analyses are
highly specific and quantifiable.
The sampling procedure is simple and inexpensive. Yet the sampling strategy
and results interpretation require a thorough understanding of the process.
In the past, the medical community has performed the sampling, but most
of the sampling has been diagnostic, involving expensive clinical tests performed on the distressed sufferer. Where allergies appear widespread in an
office building or other problematic indoor air environment, the perplexed
facilities manager or homeowner seeks assistance from the environmental professional. Diagnostic tests on all the building occupants can be expensive and
time-consuming. In such instances, dust sampling is by far the more feasible
alternative.
Yet without the benefit of clinical studies, extensive allergy complaints
may pose a medley of possibilities. Some of the allergy sufferers know the
specific antigens that cause their individual reactions. Known allergens may
assist in narrowing the possibilities, where dust sampling may be performed
in order to:
• Define allergen levels in residences of asthma patients.
• Identify areas or sources of elevated levels of allergen(s).
• Determine the effectiveness of allergenic dust control measures.
247
248
Indoor Air Quality: The Latest Sampling of Analytical Methods
Most of the information provided within this chapter is intended to aid
in the search for the more common allergens and expound on those that
may be overlooked in isolated instances. The animal allergens are more
widely understood and are an evolving issue of concern in the environmental field.
Animal Allergens
Animal proteins are high molecular weight, complex molecules that can elicit
an allergic reaction. Wherein the environmental professional is concerned
with airborne exposures, the allergens must be present in large quantities and
small enough to become airborne. Typically, those animal allergens that are
more commonly encountered are parts and pieces of an insect or mammal.
Those that receive the greatest attention and are frequently studied are dust
mites, dog/cat dander, and cockroach body parts. The probability of elevated
numbers of these allergens is considerable in most indoor air environments.
Mites/Spiders1, 2
Mites are small to microscopic sized, generally parasitic arachnids with four
pairs of legs in their adult stage and little or no differentiation of the body
parts. Many cause allergic rhinitis, human dermatitis, and general allergic
reactions. They differ in habitat and associations and are broadly categorized by their associations. See Table 15.1 for a breakdown of the most commonly cited allergenic mite types.
Storage mites are usually of the genera Lepidoglyphus and Tyrophagus. They
rely on decaying vegetation as a food source and are normally associated
with agricultural environments. They have been identified as causing allergic rhinitis in dairy farmers. Thus allergy-causing storage mite exposures
are limited more to the outdoor environments where there is decaying vegetation than to the indoor air environment. Decaying vegetation is a requirement for their presence.
Itch mites and mange mites may cause dermatitis and have occasionally
been implicated with house dust mites. Their main food sources are cheese,
dried meats, flour, and seeds. They damage and contaminate these commodities while having a means of transportation through human handling of the
food products. The result is grocer’s itch, or miller’s itch.
Some mites and spiders attack man and other animals directly, burrowing
into their skin. These are the ones that hikers and hunters often encounter
in wooded areas.
Others cause mange, which results in itching and hair loss. Mange mites
typically attack domestic animals and are generally visible to the naked eye.
249
Animal Allergenic Dust
TABLE 15.1
Allergenic Mites
Class: Arachnida
Order: Acari (Acarina)
Suborder: Psoroptoidea
Storage Mites
Family: Acaridae, Glycophagidae, and Blomia
Genus/species:
Acarus siro
Glycophagus domesticus
Lepidophagus destructor
Tyrophagus putrescentiae
Blomia tropicalis
Itch Mite
Family: Sarcoptidae
Genus/species:
Sarcoptes scabiei
Dust Mites
Family: Pyroglyphidae
Genus/species:
Dermatophagoides pteronyssinus
Dermatophagoides farinae
Dermatophagoides microceras
Euroglyphus maynei
Source: Halsey, J.F., and M. Colwell. Allergy Basics for IAQ Investigations. (Handout)
Professional Development Course, American Industrial Hygiene
Conference and Exposition (May 20, 1995). With permission.
Yet following a heavy infestation, dead or alive, their bodies may still serve
as antigens.
House dust mites have undergone considerable study as they are not only
allergenic, but they typically are found indoors. See Figure 15.1. They bask in
warm, moist, dark environments. Ideal temperatures are between 70°F and
80°F. They thrive where the relative humidity is in excess of 65 percent, and
they hide from sunlight.
Sites where they tend to commune are places that have sloughed epithelial
cells (which tend to retain moisture), such as beds, upholstered furnishings,
and carpets. The average human will lose as much as five grams of epithelial
skin cells per week. Wherever these epithelial cells can be found, the mites
have a source of food.
In the United States, dust mite infestations and allergies tend to be seasonal
with a preference for the warmer, humid months (e.g., summer). Whereas
tropical climates may provide a perpetual, unrestricted habitat for blissful
invaders all year round, the pesky little critters predominate mostly between
June and August.4
The house dust mites are between 250 and 500 microns in size, barely visible by the naked eye and frequently overlooked. The allergenic portion of
250
Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 15.1
The dust mite is a commonly used representation of allergens. (Courtesy of A.L.K. Abello and
A/S Honsholm, Denmark.)
these mites is thought to be the body parts and pieces and their fecal material, which is 10 to 35 microns in diameter. The body pieces are considerably
smaller than 250 microns and not identifiable by microscopic analysis. As a
matter of course, the size has a bearing on the airborne allergens. If greater
than 40 microns, airborne substances will settle out within 20 to 30 minutes.
Thus inhalation of the material is most likely to those components of the dust
that are smallest and in areas often disturbed.
Areaslikelytobedisturbedaresituationdependent.Commonlyinvolvedactivities that might stir up dust include, but are not be limited to, the following:
•
•
•
•
•
During and shortly after vacuuming
Considerable activity on and disturbance of upholstered furniture
Considerable activity on and disturbance of carpeting
When making a bed and fluffing pillows
Sleeping on contaminated bedding or upholstered furniture
As for the actual allergens, several mite-associated proteins are implicated, and studies have been predominately on three species in the genera Dermatophagoides, which is common in North America and Europe.
To a lesser extent, the genera Euroglyphus and Blomia have been studied
as well, but they are more commonly encountered in Central and South
America.
251
Animal Allergenic Dust
TABLE 15.2
Allergenic Dust Mites and Immunoassay Test Groupings
Allergenic Proteins
Type
Group I
Group II
Group III
Dermatophagoides farinae
Dermatophagoides microceras
Dermatophagoides pteronyssinus
Euroglyphus maynei
Der f 1
Der m 1
Der p 1
Eur m 1
Der f 2
–
Der p 2
–
Der f 3
–
Der p 3
–
For the purpose of allergen testing using immunoassay techniques, the dust
mite allergens are genus and species specific, and each of the species has as
many as 40 different proteins that could cause an allergic reaction. Where
identified, allergenic proteins are referred to by group. See Table 15.2 for the
most commonly implicated allergen types and associated allergenic proteins.
Where a group of allergenic proteins has not been identified, a homogeneous mix is referred to as polyclonal. A polyclonal assay involves multiple
antigens from the same life form.
Booklice
Oftentimes, the layman will refer to paper mites as being the source of a
problem, possibly because the individual associates their allergies with the
mounds of paper they work with and hearsay. The reference to paper mites
is a red herring, a fictitious contrivance of the news media. Entomologists
frown on desperate attempts to track these elusive pests under the heading
of mites. While some entomologists will confess ignorance, others will speculate that the reference is more likely to that of storage mites that, at times,
are associated with cellulose, or paper products. Another consideration is
that of booklice are neither mites nor lice, but insects. See Figure 15.2.
Booklice belong to the order Psocoptera. These are small, soft-bodied
insects with three pairs of legs and measuring less than 1/4-inch in length.
They may or may not have wings. They have been reported as causing allergic symptoms in places with large amounts of paper. They feed on molds,
fungi, cereals, pollen, and dead insects. Their preferred habitat is moist areas
and humid environments, and they rarely cause damage to the spaces they
occupy. They are, however, a nuisance to allergy sufferers.
Cockroaches and Other Insects5
Insects are typically visible, have three pairs of legs in their adult stage, and
possess three distinct body regions. They are, therefore, easy to identify, and
a large indoor insect population rarely remains unnoticed. The most common is the ever-present cockroach.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 15.2
Photomicrograph of an “unconfirmed” booklice, a component of office dust, lifted by tape. Its
approximate size is 500 microns, and this image was observed, in its entirety, under 100x magnification. Immunoassay testing was for cockroach allergens only, which were found to be excessive. Dust mite allergens were low, but the method was specific for dust mites, not booklice.
Of the 55 species of cockroaches that inhabit the continental United States,
less than 10 are indoor residents. Of these, the most common, particularly
in southeastern United States areas, are the larger American cockroach
(Periplaneta americana) and the smaller German cockroach (Blatella germanica).
See Figure 15.3. As the larger ones consume the smaller, more prolific ones,
they do not tend to cohabit within the same residence. It should be visually
apparent as to which species one is dealing with. Yet allergy tests are genus
and species specific. See Table 15.3 for the allergenic groups.
Recent studies, however, suggest that the cockroaches secrete their allergens
onto their bodies and other surfaces in their environment. Thus examination
of allergenic material may or may not disclose the presence of associated
debris and fecal material. The only means of confirming the presence of cockroach allergens is through immunoassay analysis of suspect dust.
There has been considerable, unconfirmed speculation as to the source of
the cockroach allergens. Some considerations are as follows:
•
•
•
•
Saliva
Body parts and pieces
Egg shells
Fecal particles
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Animal Allergenic Dust
FIGURE 15.3
The American cockroach (Periplaneta americana) [left] and the German cockroach (Blatella
germanica) [right].
Cockroaches are able to adapt to low ambient humidity, yet actively seek a
source of water. For this reason, indoor cockroaches are most likely found
around water pipes, pet water bowls, evaporative areas around refrigerators,
leaking faucets, and wet carpeting. Although in most cases their presence is
readily apparent, cockroach allergens have been measurable in up to 15 percent of homes that had no visible clues that they might be present. Keep in
mind that they do not have to be alive for the allergens to promote a reaction,
and the source of cockroach allergens is still unclear.
Although there have been numerous allergen studies performed of the
ever-enduring, ever-present cockroach, many other insects have been implicated as well. Though most other insects are generally found in outdoor
environments, body parts and pieces may be conveyed indoors. They may
attach to clothing. They may enter open windows and doors in search of
food or light (e.g., june bugs). There may be air movement from the outside
to enclosed air spaces indoors. Indoor accumulations of insect carcasses are
common. The indoor environment may become a repository of debris.
TABLE 15.3
Allergenic Cockroach Material and Immunoassay Test Groupings
Blatella germanica
Periplaneta americana
Allergenic
Group I
Proteins
Group II
Bla g 1
Per a 1
Bla g 2
–
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Outdoor workers are exposed, at times, to insect fragments and debris at
levels in excess of ragweed pollen. Insects that are suspect of causing allergies include the following.3
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Crickets
Bean weevils
Houseflies and fruit flies
Some species of moths
Waterfleas
Butterflies
Bed bugs
Silkworms
Mayflies
Caddis flies
Aphids
Chiromomid midgets
Honey bees
June bugs
Some occupations, due to their associations, harbor potential exposures for
insect infestations. Some examples may be found in Table 15.4.
Domestic Animals 6
Most allergic substances that are associated with domestic animals are predominately exposure problems in environments where the animals reside.
The obvious is overstated. Homes, kennels, pet shops, and laboratories
are locations where the allergens are most likely to be found. However,
office environments should not be excluded from consideration. Although
TABLE 15.4
Occupational Exposures to Insects
Entomologists: locusts, crickets, flies
Grain mill workers: beetles, grain weevils
Loggers/lumber mill workers: Tussock moth
Fishermen/bait handlers: meal worms, maggots
Poultry workers: Northern fowl mites
Bakers: storage mites, grain weevils
Small animal handlers: fleas
Honey-packing plant workers: honey bee dust
Pet food processors: Chironomids
Animal Allergenic Dust
255
rare, elevated exposures have been reported where the source has not been
readily apparent. The most commonly targeted domestic animals are cats
and dogs.
Cats
Although cats are maintained in 28 percent of all American households, only
2 percent of the U.S. population has allergies to them. Interestingly, those
who are allergic to cat allergens may never have lived with cats.
The source of allergenic material may be any of a number of feline-associated materials, and tests are performed for the allergen Fel d 1. There has been
considerable speculation as to the actual chemistry of the allergen, but most
researchers have speculated that the allergen is somehow transferred, picked
up, or concentrated by saliva. When the cat grooms itself by licking, the allergen is spread or transferred to the hair and epithelial cells. The following is
an abbreviated list of known and suspect sources/transfer vehicles:
•
•
•
•
•
Saliva
Sebaceous glands
Hair
Epithelial cells
Epidermis
The sex and type of cat are factors that contribute to environmental levels of
cat allergen. Male cats shed more allergens than female cats. Patients’ symptoms vary in severity, depending upon the type of cat to which they are
exposed to (e.g., a domestic cat versus a Persian short tail).
The cat allergens are carried on particles less than 2.5 microns in diameter
(i.e., PM 2.5). At this size, after becoming airborne, they will remain suspended in an undisturbed environment for hours. The ease with which these
allergens become airborne is the reason for apparent excesses in sensitivity.
Even though there are excessive cat allergens in a household where one
resides, all indoor environments have detectable levels. In houses with cats,
there is typically in excess of 10 micrograms per gram (µg/g) of Fel d 1 in the
dust, and levels have been reported as high as 7000 µg/g.7 The allergen may
also be transferred by clothing and other articles from a high exposure environment to otherwise cat-free environments. Houses that have never had
cats may have levels of less than 1 µg/g in the dust, but levels in excess of this
should not be surprising.
Dogs
Dogs are maintained in an estimated 43 percent of American homes, and
one regional study indicated that as many as 17 percent of the population
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Indoor Air Quality: The Latest Sampling of Analytical Methods
was allergic to dog allergens. There have been 28 different allergens found
to be associated with allergic symptoms. The specific antigen to which most
patients react is designated as Can f 1. Can f 1 consists of an extract of the following dog associated materials:
• Hair
• Dander
• Saliva
Most environments where dogs are found have in excess of 120 µg/g of Can f
1 in the dust. Homes without dogs typically have less than 10 µg/g. The size
of the allergen-carrying material or contaminated particles is unknown.
Rodents8, 9
Exposures to mouse and rat allergens are typically associated with animal
research laboratory vivarian and indoor spaces (e.g., homes and office buildings) infested by rodents. Of the approximately 35,000 workers in the United
States exposed to rodent allergens in animal research laboratories or breeding
facilities, more than 20 percent of the workers experience allergic symptoms.
Rodent infestations may deposit allergens unbeknownst to building occupants. Awareness of the potential opens another door for search and disclosure of possibilities. Complaints of a urinelike odor should alert suspicion.
Two other allergens have been associated with mice. One of the mouse
allergens, referred to as Ag 1, is related to the mouse urine and is designated
Mus m 1. Mus m 1 is produced by the liver and salivary glands, excreted in
the form of urine and saliva. As it is associated with testosterone, Mus m
1 is excreted predominately by male mice. Other factors affecting quantity
are strain and age. The other mouse allergen, referred to as Ag 3, has been
detected in hair follicles (e.g., fur and dander extracts).
Two allergens have also been associated with rats. However, they are both
associated with the rat urine. These allergens, referred to as Ag 4 and Ag 13,
are designated Rat n 1.
Although typically associated with particles of 10 microns in size or less,
airborne exposures to rodent urine rarely occur unless contaminated bedding is disturbed, and elevated humidity has been reported to diminish airborne exposures. Most exposures occur where rodents are maintained in
large numbers (e.g., laboratory environments). The amount of material that
may become airborne is generally related to the type of litter and bedding.
The allergen is generally released into the air during cage-cleaning activities. In one laboratory animal cage-cleaning study, the airborne levels were
reported between 19 and 310 nanograms per cubic meter of sample (ng/m3).
During quiet times, when there were no disturbances, the levels dropped to
around 1.5 to 9.7 ng/m3. Rodent allergens may also be deposited on ceiling
Animal Allergenic Dust
257
tiles and in carpeting. Disturbances of contaminated areas may result in
airborne releases of material as yet not identified to be present in a given
environment (e.g., rodent infestations). There is no published information
regarding reported airborne or dust levels of rodent allergens.
Farm Animals10
Along with the arthropods, pollen, mold spores, and bacteria, farmers and
farmworkers are potentially exposed to farm animal allergens. The more
prominent allergenic exposures are attributed to cows, horses, and pigs.
Cow dander and urine, designated Bos d 2, have been reported to cause
allergic rhinitis in dairy farmers. Airborne levels have been reported as high
as 19.8 µg/m3.
Horse allergens (Equ c 1, Equ c 2, and Equ c 3) are very potent. Exposures
may occur occupationally or to pleasure horseback riders. The horse allergens are related to hair, dander, and epithelial cells.
Pig allergens are rarely reported to be a problem and are considered weak
antigens. The allergenic material has, however, been identified. Swine workers have been found to have antibodies against swine dander, epithelium,
and urine. Airborne levels have been reported up to 300 µg/m3. Yet there
appear to be minimal complaints and concerns for swine allergies.
Other Animals10
Rabbit dander and guinea pig urinary proteins/saliva have been reported to
cause allergies. Both are found in homes, pet stores, and laboratory facilities.
Even rarer are exposures to bat guano and reindeer epithelial cells. Bat
droppings accumulate inside roof attics and cave dwellings. Asthma like
symptoms are generally reported in association with workers exposed to
bats in indoor working environments.
Reindeer epithelial cells, which are associated with leather processing, are
also known to cause allergic reactions. Airborne exposure levels have been
reported in processing areas at a concentration of 0.1 to 3.9 µg/m3.
Occurrence of Animal Allergens
Farm, laboratory, and pet environments are easy marks. The source of allergies is direct and readily apparent to the allergy sufferer when symptoms
worsen in their presence. The greater the number of animals, the greater is
the potential for elevated exposures. Whereas an individual may not at one
time have been sensitive to a given allergen, an extreme dose may later predispose them to developing symptoms at lower exposure levels in the future.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Most of these allergy sufferers know what it is they are allergic to. A small
percentage of the population, however, seems to be sensitive not only to the
typical allergens, but to just about everything.
In office environments with no apparent sources of animal allergens,
the latter more allergen-sensitive individuals will be the first to start complaining. It has been estimated that these ultra-sensitive individuals constitute only about 4 percent of the population. Yet as levels of an allergen
increase, the numbers impacted increase as well. With more complaints
comes greater concern for locating a source. As animal allergens are possible contributors to a given environmental invasion, a means for identifying
and quantifying their presence is made available through a well-thoughtout strategy, collecting dust samples, and analyzing the collected material
by immunochemisty.
Sampling Strategy
A well-thought-out strategy is vital for identifying a problem and obtaining
meaningful results. If the environment is an office building and large numbers of people are impacted, the problem areas must be clearly identified.
Questionnaires should be filled out by all those in the area of concern
as well as an area where there are no complaints of allergylike symptoms.
Identify known problem areas and nonproblem areas. Develop associations.
Attempt to limit the possibilities. A screening tool for rodents, using ultraviolet light, may also be added to the list of considerations. The method is
discussed in the next section of this chapter.
Other than bacterial and mold spores, the most typical allergenic materials found in office buildings are dust mites and cockroach allergens. Cat and
dog allergens are more common in homes but may be transferred to office
environments. All other allergens previously mentioned are rare occurrences
in office/industrial environments or are occupationally related.
Some building occupants may have had allergy testing (e.g., skin or allergy
blood tests) performed and know what allergens to which they are allergic.
A few of the more common blood tests available through physicians include
the following:11
•
•
•
•
•
•
Plant pollen
Fungi/molds
Thermophilic actinomycetes
Storage mites
Animal dander
Isocyanates
Animal Allergenic Dust
259
• Formaldehyde
• Gums/adhesives
• Anhydrides
The greatest dilemma to the environmental professional is that of locating
areas most likely to be source origins and including only these in the sample,
not the disassociated areas as well. For instance, if complaints generally arise
in a given area where there is a lot of disturbance of the carpeting and dust
mites are suspect, the area where the traffic passes should be sampled to
include as much of the known problem material as possible, including areas
under desks and along walls that may or may not be the source origins. Each
falls within a different source type (e.g., carpeting) and functional grouping.
Sample sites should be selected based on suspect source types. These may
include, but not be limited to, the following locations:
•
•
•
•
Carpeting
Upholstered furniture
On top of ceiling tiles
Ducting in an air handling unit
Functional grouping of sample sites is the most difficult to identify. The
impacting function may or may not be obvious. In most cases, it will not be
obvious, and several functional areas will require sampling. Grouping may
include, but is not limited to, the following:
•
•
•
•
•
Dusting shelves
Vacuuming the carpeting
Excessive traffic
Maintenance involving removal of ceiling tiles
Air handler activity
The number of samples taken will depend upon the environmental professional’s assessment of the situation. This will vary in a case by case situation,
depending upon the number of possibilities ascertained to be a potential
problem source. Then, too, sampling of a nonproblem area may be desirable
for comparative purposes.
During data/information gathering, clarify whether a suspect carpet was
recently shampooed or vacuumed. Maybe there has been a recent infestation
of cockroaches or rodents. Even where the vermin have since been exterminated, their body parts and pieces may be the exposure allergens. In locating
possible sample sites where these parts and pieces may have been deposited,
the environmental professional should also consider the function of that
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Indoor Air Quality: The Latest Sampling of Analytical Methods
location as well. For instance, rodents may eat through air supply ducting
and leave a trail of urine and feces. Allergenic material deposited in an air
plenum will pose a greater potential for occupant exposures than the same
material deposited in the corner of a room where there is no foot traffic or
air movement.
Record the sample area size and exact location. Although the area size may
not be relevant (samples are analyzed by weight comparisons), this additional information may be useful at some future date, and some professionals do standardize the sample size (e.g., 1 cubic meter of area). You, once
again, are not obligated to do the same.
Although there is no set protocol, sample sites should be clearly identified.
If floor plans are available, indicate the limits of each site and assign a sample
number to the area. Otherwise, describe in detail the specific location(s) (e.g.,
on top of the ceiling tile above the copy machine) with its perceived function
(e.g., frequent above ceiling work necessitates disturbance of ceiling tile at
this location).
Screening for Rodents12
Public health food inspectors screen for the presence of rodents in a food
processing plant by using ultraviolet light. Under ultraviolet light, urine will
fluoresce (e.g., glow in the dark) either a blue-white or a yellow-white color.
Fresh stains fluoresce blue and older stains fluoresce yellow.
Rodents are incontinent. They tend to urinate, mark their trail as they go,
and the trail is easy to follow. Rodent hairs also fluoresce as does the urine.
For this reason, rodents can easily be identified in areas they frequent (e.g.,
food storage areas).
This characteristic of urine fluorescence under a UV light is a simple means
for inspections—in dimly lighted areas. The darker the area under investigation, the more visible the fluorescent stains.
Sampling Methodologies
Due to the complexity and lack of clinical comparison studies, sampling is
typically performed on settled dust. Even though air sampling can as easily
be performed, airborne levels vary considerably, because they are based on
dust generating activities that are in progress during the sampling period.
Depending upon the airborne dust levels, the required sample air volume
may be in excess of 5000 liters. Large air volumes, in turn, embrace extended
Animal Allergenic Dust
261
sampling times or environmental air sampling devices that are capable of
drawing 100 to 1000 liters per minute. If sampling times are extended, the
activity that generates airborne dust may not be singularly represented in the
sample. Then, environmental sampling equipment is expensive and cumbersome. There are no published procedures for allergenic dust air sampling,
and researchers shy away from this approach. On the other hand, settled dust
sampling is simple and clinical comparison studies have been performed.
Settled dust sampling is as easy as sucking suspect dust into a vacuum
cleaner bag or as involved as using specialty sampling devices designed to
perform allergen dust sampling. The following sample collection devices have
been successfully used by environmental professionals and allergists:13
Standard vacuum cleaner with a filter bag—The filter bag is later detached
and sent to the laboratory for analysis. Although allergenic material
was found to be retained in the hose preceding the filter bag, studies have concluded that dust collection preceding the hose or at the
end of the hose is not significantly different, but capture efficiency is
significant. High retention, high efficiency bags capture and retain
fine particulates that are the most concern as fine particles pass the
thoracic cavity and enter the lung. Losses may be as much as 30 percent to 50 percent with the low retention bags. In a pinch, high efficiency bags may be purchased in grocery/discount stores, or with
some foresight, the investigator can get specialty supplies from their
laboratory (e.g., end of hose filter cassette).
Commercial high efficiency particulate (HEPA) vacuum cleaner with a
high efficiency filter bag—The filter bag is later detached and sent
to the laboratory for analysis. This apparatus is more efficient for
retaining particles smaller than 2.5 microns in diameter than most
conventional vacuum cleaners. To avoid cross contamination, assure
the hose and all connectors between the intake wand and filter have
been cleaned prior to each collection. This approach may be applied
wherein a very large volume sample is required.
Specially designed dust vacuum with an external filter attachment—One specialty design is a small, easy-to-carry vacuum cleaner to which one
may attach collection media (e.g., Dustchek filters) to the end of the
hose. The standard and commercial vacuum cleaners generally have
a higher sample collection rate, and most of the smaller specialty
vacuums are not practical for collecting samples over large floor
areas. See Figure 15.4.
Air sampling pump with a polycarbonate or PVC membrane filter cassette—
Samples are drawn through the polycarbonate or PVC filter cassette
with an air sampling pump at a flow rate of 10 to 20 liters per minute. This method requires longer sample times to collect the minimal
sample size (e.g., half a teaspoon of dust).
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Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 15.4
Specially designed dust vacuum—EMDust Vacuum System (EMLab/P&K, Phoenix, Arizona).
A private laboratory performed comparison tests for some of the above sampling devices and concluded that there is a significant difference in their
allergen dust recovery. They ranged from half the original sample dose to
double. For this reason, the same method should be used consistently, and
comparison sampling of problem and nonproblem areas is strongly indicated so as not to rely on threshold values only.13
Commercial laboratories emphasize that the principal consideration
in sampling should be the quantity of material captured. Although some
researchers propose sampling within a well-defined, delineated area or a
limited sample duration, the quantity of material collected may not provide
a good representation of the environment or allow for a sufficient amount of
collected dust to retain the desired sensitivity (e.g., picograms). Those who
define the area of surface coverage generally opt for 1 square meter. Others
sample for a specified time period (e.g., 2 minutes), no matter what the substrate. They typically vacuum for a set period of time (e.g., 5 or 10 minutes)
without regard to the area covered. Yet in both instances, the amount of dust
collected still relies on the amount of available dust. There is no such thing
as too much collected dust. There may, however, not be enough.
Ideally, the environmental professional should be able to estimate the
amount of dust collected and target a collection in terms of milligrams (with
the volume dependent upon the density of the collected material). Some laboratories specify 250 milligrams (i.e., half teaspoon of dust). Others specify 500
milligrams. The latter allows for a certain fudge factor with plenty to spare.
Although not required, composite sampling is recommended where several samples are to be taken and the primary allergenic reservoir has not been
identified. One study indicated that three composite samples taken from the
same dwelling, each a week apart, gave similar results. There was, however,
a noted difference between areas within the same dwelling and between
Animal Allergenic Dust
263
dwellings. Thus composite samples provide a relatively consistent estimate,
and discrete samples were useful in finding specific reservoirs.13, 14 These
samples may be taken during the collection process or involve a contribution
of dust from each of the samples taken in areas known to be associated with
airborne allergens. This approach can be useful for screening and minimizing the number of samples requiring analyses for all allergenic dust.
In brief, the most relevant consideration is locating the sample site. Isolate
and identify a specific, suspect sample site (e.g., around an area known to be
associated with allergic reactions) along with its function/activity (e.g., high
foot-traffic area or bedding). Then collect a sample (or a composite of several
samples). Compare suspect problem sites with known nonproblem sites. If
an allergen appears suspect, discrete area sampling and analyses will aid in
the identification of reservoir(s). Comparison sampling, coupled with published thresholds, will result in manageable interpretations.
Analytical Methodologies
For the purpose of extending the reader’s knowledge into the realm of understanding human test results and their applicability to a site investigation, human
testing methods are discussed in brief within this section along with sample
analytical methods. They are both relevant in assessing suspect allergens.
Human Testing
Airborne exposures to animal antigens may result in allergic rhinitis, sinusitis, and asthma. Although dermatitis and urticaria have not been implicated
with airborne exposures, where an allergic individual rubs up against dust
laden with a given antigen, the skin may be impacted as well.
Allergenic individuals may be tested by any of a number of means, each
associated with a different route of entry or means of exposure. The simplest
and most frequently used method is the direct skin test.
The skin test technique primarily allows for identification of direct contact
allergens only. It will not provide for identification of airborne allergens. A
suspect antigen or group of antigens is placed on the skin surface of the
individual, usually a site on the arm, and a retentive barrier is placed over
the material. The site is checked for redness and urticaria after 24 hours. A
positive reaction indicates the individual is sensitive to all or one of the challenge allergens.
A less commonly used technique is that of blood sample analysis. Blood
is extracted from the individual and analyzed by immunochemical techniques. This method is by far the less invasive, not challenging the individual allergy sufferer. The immunochemical techniques used are the same as
264
Indoor Air Quality: The Latest Sampling of Analytical Methods
those used for the dust samples and are discussed in a little more detail
under “Allergenic Dust Testing.”
The most ideal (and impractical) technique is that of a direct bronchial
challenge to the individual. This method provides a direct insult to the
individual while they are restricted to a challenge chamber where the airborne allergen types and amounts may be controlled. Whereas one may not
respond to the skin test, the bronchial insult chamber may elicit a respiratory
reaction. The technique is mostly of the research mode and, if accessible, is
very expensive and time-consuming.
Allergenic Dust Testing
Commercial laboratories currently offer routine testing for dust mite, cockroach, cat, and dog allergens. Although an occasional commercial lab may be
willing to extend their limits, several research institutions have the materials
necessary to test for the less common allergens (e.g., Mus m 1). Immunoassay
testing of allergenic dust is extremely sensitive and highly specific. This
specificity is advantageous in most cases but can be a drawback where a
similar, but not identical, allergen is suspect.
Sample preparation involves sieving the dust samples to separate all material less than 300 microns in size from the larger material. After it has been
weighed, the smaller material is then extracted with a special buffering solution. An aliquot is taken of this extract and analyzed by any of a number
of immunoassay approaches, involving single antigen specific or multiple
antigen quantitation.
A single specific protein, or antigen, is referred to as “monoclonal.” An
example of a monoclonal test antigen is Fel d 1. Being related to and being
the strongest (or most studied) allergenic component of a given species, the
monoclonal antigens become the most commonly sought after test material. Yet, due to the extensive amount of attention given to a limited number of allergenic species, the specificity of these methods may restrict the
possibilities.
Those species that have received the most attention are also those that
are known to cause allergies and are prevalent in significant numbers.
Figure 15.5 shows the results of a study involving school children and prevalence of allergies. As a child ages, allergies diminish until ages 25 to 34.15
Thus the prevalence of the various allergies is likely to be less in the adult
population.
Multiple proteins from one species or several are referred to as “polyclonal.” An example of a polyclonal test antigen is cat allergens. They have
not been as extensively studied as the monoclonal antigens, and results seem
to be less consistent and are more difficult to evaluate.
The identification of polyclonal antigens, however, may provide direction
and assist the environmental professional in isolating the probable allergenic
species in a dust sample. It serves well as a screening mechanism. More
265
Animal Allergenic Dust
30%
25%
20%
15%
10%
5%
0%
Cockroach
Parts and
Pieces
Mold
Spores
Animal
Dander
Grasses
Dust Mites
and Weeds
FIGURE 15.5
Estimated prevalence of allergies in school-age children and skin reactivity tests. Excerpted
from Indoor Allergens.16
reliable, easier to use results may then be obtained through the monoclonal
antigen tests. If, however, the screening fails to disclose any of the common
allergens, all is not entirely lost.
An environment may be complicated by rare occasional, outbreaks or isolated occurrences. Elevated levels of fleas identified in the carpeting of a
high-traffic medical reception room cannot readily be assayed. Dust that
is known to be the source of allergies cannot readily be identified if the
components are other than the more common species. Any of a number of
scenarios may develop. In these instances, some laboratories will prepare
test material from a given dust sample and test the blood of the allergy
sufferers to confirm the allergenic potential of the material. The extracted
dust is injected in a strain of mouse. If allergens are present, antibodies are
formed. The newly created antibodies are then used to test for dust allergen in an allergy sufferer’s blood. Sampling and interpretation require the
assistance of a medical doctor.
Interpretation of Results
A dose–response relationship is recognized with allergens as it is with
toxic chemicals. A small percentage of the population will experience
the effects at extremely low levels of exposure, levels not even noticeable
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Indoor Air Quality: The Latest Sampling of Analytical Methods
to a majority of the population. These highly sensitive individuals are
thought to comprise less than 5 percent of the workforce. Although this is
in line with chemical sensitivity numbers, the more sensitive individuals
comprise a group of people who were: (1) predisposed at birth; and (2)
exposed to low levels of specific antigens for a long duration. The remaining 95 percent of the population will be impacted as the exposure levels
increase.
Ideally, problem area composite samples should be compared with nonproblem area composite samples. Composite results may identify suspect
allergens, and discrete samples will help to isolate the reservoir. Although
most environmental professionals find great comfort in acceptable limits, comparisons with published thresholds should be accomplished with
reserve.
Thresholds are in a constant state of flux, and recommended limits may
vary from one laboratory to the next. Observations vary by region, and
available species differ. Analytical results on the same sample may vary
from one laboratory to the next. Laboratory findings and allergenic association tend to be variable, and these findings change within the same laboratory. For this reason, published thresholds should be used as a guide
only!
For reference and review, some of the commonly accepted allergy-causing
thresholds can be found in Table 15.5. Yet they are not firm, hard-clad references. These limits are the result of observations made as to measured levels
and resultant responses of typically nonatopic individuals. These reference
values will not be applicable for those predisposed to allergies. In these
TABLE 15.5
Allergen Levels in Dust Capable of Eliciting an Allergic Response in
the General Population Not Predisposed Genetically to Allergies
Allergens
Dust mite allergens (polyclonal)a
Der f 1
Der p 1
Group I
Cockroach allergensb
Bla g 1
Cat allergensb
Fel d 1
Dog allergensb
Can f 1
a
b
Reference
Thresholds (µg/g)
1517
217
217
1018; 219
220
818; 819
–
Dermatophagoides farinae and Dermatophagoides pteronyssinus.
Polyclonal antigens for which there are no published references.
267
Animal Allergenic Dust
atopic individuals (15 percent to 20 percent of the adult population), their
thresholds may be 1 percent of that which will potentially impact the general
population. It should also be noted that immunoassay reference thresholds
for plant pollen, mold spores, and chemicals are not listed. This is due to the
direct means available for determining airborne exposure levels for some or
to the lack of data for reference thresholds.
Another publication sets different range limits, stating that their measurements are the most practical reference values available. They provide the
following limits for Group I dust mite allergens:20
• Safe levels: less than 2 µg/g
• Levels that may sensitize atopic (genetically predisposed) individuals: 2 to 10 µg/g
• Levels that may exacerbate previously sensitized individuals: greater
than 10 µg/g
It is thought that the Group I dust mite allergens are associated with
fecal material that is relatively small in size as compared with the larger
Group II allergens that are associated with the body parts. Thus the
Group I dust mite allergens are those most likely to be disturbed and
become airborne. They are the most likely to be associated with allergy
symptoms. The Group II body parts may complicate an evaluation where
an individual is close to the settled allergenic material (e.g., sleeping on a
contaminated pillow or lying on the floor). All conditions must be taken
into consideration.21
Attempts have been made to report observed thresholds for airborne exposures to rodent allergens. One such attempt is summarized in Table 15.6. As
these numbers are variable and not well-studied, they should be used with
reservations. At best, they may be considered reference guidelines. Dust air
sampling should be performed through contributing input from the laboratory that will perform the analysis.
TABLE 15.6
Allergen Levels in Air Reported to Cause an Allergic
Response
Thresholds
Observed
Thresholds
Rodent Allergens
Ag 3
Mus m 1
Rat n 1
825 µg/m3
59 µg/m3
–
Source: Twiggs, et al. Journal of Allergy and Clinical Immunology.
69:522 (1982). With permission.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Other Types of Allergenic Substances
Other types of allergenic substances include indoor/outdoor allergens and
industry-related allergens. Indoor/outdoor allergens are mold spore allergens.
Mold spore dust sampling is rare. Easier, more commonly accepted
approaches are available for analysis (as has been discussed in previous
chapters), and there are limited guidelines for interpretation of results. In one
report, the researchers suggest that should the fungal spores and bacteria in
dust exceed 10,000 colony forming units per gram of dust (CFU/g) remediation may be indicated. Fungal concentrations on water-damaged materials
(e.g., carpeting, gypsum board, or ceiling tiles) are excessive if they exceed
1000 CFU/g or 1000 CFU/cm2. However, the analysis for fungal spores relies
on spore viability and is performed by the use of a culture media and petri
dishes. There are no immunoassay methods currently being used for mold
spore quantitation in dust, but there are immunoassay methods to determine if an individual is allergic to specific mold spores. History must dictate
allergies, and the testing is performed for specific genera.
In certain industries, some of the more common allergenic proteins for which
immunoassay methods may be performed have been identified in Table 15.7.
Currently, however, processing of the samples may involve considerable
expense or the aid of a research laboratory. There has been minimal or no dust
sample analyses of these materials, and interpretation may be elusive.
Although each of the above allergens can be analyzed by immunoassay
methodologies, many of the chemicals may be sampled using traditional
industrial hygiene air and surface sampling methodologies. Once a laboratory has been identified to perform an analysis, the feasibility of performing
air sampling for occupational allergens in the food processing industry will
be based on one’s willingness to collect comparative samples in nonproblem
areas and compare them to problem areas or with symptoms in order to
establish an acceptable limit.
Then, also, the environmental professional may encounter a situation
whereby dust from a grain elevator or adjacent food processing plant
appears to be causing problems for the occupants of a building that is
associated only by proximity to the food processing plant. In such cases,
TABLE 15.7
Allergenic Materials That May Become Airborne
Industry
Food processing
Chemical/industrial
Type
grain, flour, coffee bean, castor bean,
egg, garlic, and mushroom dusts
latex proteins, isocyanates, metals,
resins, dyes, and drugs
Animal Allergenic Dust
269
source dust samples in the immediate vicinity of a given building may be
compared to dust collected indoors. Where symptoms indicate a probable
exterior source, some of the occupants may also be tested with the aid of a
medical doctor.
Of the chemical/industrial sources, latex protein analysis can be performed by immunoassay of a patient’s blood. Drug dispersion sampling is
often performed in house by the pharmaceutical company laboratories, and
the other chemicals can be sampled/analyzed as chemicals (not allergens)
and compared with published reference limits for toxicity and sensitization
levels.
Natural rubber latex proteins (produced from the sap of the Hevea brasil­
iensis trees) cause dermatitis to many of those who wear latex gloves, particularly to those in the medical professions where frequent use of the gloves
is required. The frequent use and replacement of these gloves in an operating room are reputed to be the potential source of airborne latex proteins
in the operating rooms. Of considerable concern, airborne latex proteins in
an operating room, where the patient’s system is accessible, may result in
anaphylactic shock and possible death if the patient is already allergic to
latex proteins. Another surprise use and source of airborne latex proteins
has been reported in fireproofing material sprayed on structural members
of buildings.
In one case, analysis of the fireproofing insulation was performed. The
concentrations of latex protein were 1000 to 2000 nanograms per gram of
material (ng/g). Samples of blood were taken from 36 occupants, and 4 tested
positive. The dust tested positive (5 to 26 ng/100 cm2), and the airborne concentrations ranged from nondetectable to 16 ng/m3. The only confirmation
of the latex allergens as being the cause of skin rashes and other allergic
reactions was remediation that led to elimination of the symptoms. Although
there were no controls, the latex-containing fireproofing was implicated as
the probable source of building complaints.24
Summary
Animal allergens that can be identified by the immunoassay methods discussed herein are limited. The investigator should be aware of those that
are possible and those that can be analyzed. For those that cannot be analyzed by immunoassay, the author suggests forensic dust analysis or guilt by
association. For instance, if there are bats residing within a building and the
occupants are experiencing allergy symptoms, the investigator may seek to
confirm by forensic dust analysis the presence of insect parts and pieces. See
the cover of this book for a photomicrograph of bat guana.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
References
1. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), pp. 134–37.
2. Borror, D.J., and D. DeLong. Introduction to the Study of Insects, 3rd ed. Holt,
Rinehart and Winston, New York (1971), pp. 634–637.
3. Halsey, J.F., and M. Colwell. Allergy Basics for IAQ Investigations. (Handout)
Professional Development Course, American Industrial Hygiene Conference
and Exposition (May 20, 1995).
4. Lintner, T.J., and K. Brame. The Effects of Season, Climate, and Air Conditioning
on the Prevalence of Dermatophagoides Mite Allergens in Household Dust.
Journal of Allergy and Clinical Immunology. 91(4):862–7 (April 1993).
5. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), pp. 138–39.
6. Ibid., pp. 151–53.
7. Lintner, T.J. Topics on Allergens (Oral communication). Vespa Laboratories,
Spring Mills, Pennsylvania (October 1995).
8. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), p. 154.
9. Jones, R.B., et al. The Effect of Relative Humidity on Mouse Allergen Levels
in an Environmentally Controlled Mouse Room. American Industrial Hygiene
Association Journal. 56:398–401 (1995).
10. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), pp. 154–55.
11. Halsey, J.F. IBT Reference Laboratory, Specializing in Environmental Allergen Testing
(Bulletin). IBT Reference Laboratory, Lenexa, Kansas. pp. 2–3.
12. Sylvania. Black Light Radiant Energy (Engineering Bulletin 0-306). Sylvania,
Danvers, Massachusetts (1996).
13. Halsey, J.F., and M. Colwell. Allergy Basics for IAQ Investigations (Handout),
Professional Development Course, American Industrial Hygiene Conference
and Exposition (May 20, 1995).
14. Lintner, T.J., et al. Sampling Dust from Human Dwellings to Estimate the Prevalence
of Dermatophagoides Mite and Cat Allergens. Aerobiologia. April 10(1):23–30
(1994).
15. Barbee, R.A., et al. Longitudinal Changes in Allergen Skin Test Reactivity in
a Community Populations Sample. Journal of Allergy and Clinical Immunology.
79:16–24 (1987).
16. Pope, A.M., et al. Indoor Allergens: Assessing and Controlling Adverse Health Effects.
National Academy Press, Washington, DC (1993), p. 52.
17. Chapman, M.D., et al. Monoclonal Immunoassays for Major Dust Mite Allergens,
Der p 1 and Der f 1, and Quantitative Analysis of the Allergen Content of Mite
and House Dust Extracts. American Academy of Allergy and Immunology. 80:184–94
(1987).
18. Trudeau, W.L., and E. Fernandez Caldas. Identifying and Measuring Indoor
Biologic Agents. Journal of Allergy and Clinical Immunology. August 94(2)2:393–
400 (1994).
19. Platts Mills, T.A.E. Allergen Standardization. Journal of Allergy and Clinical
Immunology. 87:621 (1991).
20. Schou, C., et al. Assay for the Major Dog Allergen, Can f 1: Investigation of
House Dust Samples and Commercial Dog Extracts. Journal of Allergy and
Clinical Immunology. December 88(6):847–53 (1991).
Animal Allergenic Dust
271
21. Burge, H.A. Bioaerosols. Lewis Publishers, Boca Raton, Florida (1995), p. 135.
22. Twiggs, J.A., et al. Immunochemical Measurement of Airborne Mouse Allergens
in a Laboratory Animal Facility. Journal of Allergy and Clinical Immunology. 69:522
(1982).
23. Trudeau, W.L., and E. Fernandez Caldas. Identifying and Measuring Indoor
Biologic Agents. Journal of Allergy and Clinical Immunology. 94:393–400 (1994).
24. McCarthy, L.F., K.M. Coghian, and D.M. Shore. Latex Allergen Exposures from
Fiberproofing Insulation. Presented paper under the heading of Indoor Air Quality
at the American Industrial Hygiene Conference (May 22, 1995), p. 6.
Section V
Building Systems
and Materials
16
HVAC Systems
Overlooked and underappreciated, the heating, ventilation, and air conditioning (HVAC) system is the heart and blood of a building. It is the central
conveyance of all indoor air contaminants. It may capture and entrain outdoor pollutants. It may be the source of poor indoor air quality, or it may
provide the means for improving indoor air quality.
HVAC systems are designed to provide air exchange, air cooling/heating,
and air distribution throughout a building. Sometimes indoor air quality
and HVAC design and maintenance are in conflict. The purpose of this chapter is to present the basic concepts, describe inspection abnormalities, provide a means for HVAC system sampling, and afford a means whereby this
information can be assimilated for use in an action plan.
The Basic Design1, 2, 3
A basic HVAC system consists of temperature controls, a fan to move the
conditioned air, air filtration media, heating/cooling coils and condensate
drip pan, a heat exchange condenser, and a distribution system (e.g., ducting,
air supply louvers, and return air grills). The simplest of these is the residential HVAC system.
A typical residential HVAC consists of a return air damper, a filter, cooling/heating coils, condensate drain pan, and fan—all of which are housed
in an HVAC closet. The condenser, generally located outdoors, circulates a
heat exchange fluid (e.g., refrigerant) to and from the cooling/heating coils.
Most residential units do not provide for outdoor air. Thus contaminated air
is returned back into the conditioned spaces of a home. In these cases, the
only means of diluting the indoor air where there is no outdoor air intake
is through doors, windows, and structural leaks. The tighter the building,
the less air exchange is likely to occur. Also of note, residential units have
remote heat exchange condensers with insulated condenser-to-unit conveyance line.
275
276
Indoor Air Quality: The Latest Sampling and Analytical Methods
Commercial, institutional, and some larger home systems are either similar
to that of a typical residence yet housed in a mechanical room, or the HVAC
unit is “unitized” as an all-in-one package. Mechanical rooms often serve
as a return air plenum (i.e., mixing box or chamber), and, once again, components are separate—particularly the heat exchange condenser. Separation
of components may result in heating/cooling losses when conveyed to the
conditioning coils at a remote location.
Unitized units are typically rooftop units (some enclosed within a rooftop
penthouse). See Figure 16.1. The unitized units are all in one with the exception of the distribution system. They are more efficient than the units with
the separate heat exchange condensers.
In large volume air spaces, HVAC units may be centralized (e.g., a single
unit) or decentralized (e.g., multiple units). While decentralized multiple
units require less ducting and are less expense initially, the centralized single units require a more complex means of air distribution, but less maintenance is required. Each type of unit has its own problems.
Decentralized multiple units require multiple unit maintenance checks,
multiple filter changes, and multiple repairs. Temperature controls are, however, more manageable. An office building with different occupants will
generally have a separate unit for each office space. Wherein office space is
rented, each office is generally responsible for its own HVAC energy costs and
maintenance/upkeep. A maintenance provision is generally in most office
space contracts. This is typically overlooked by the occupant and comes as a
surprise to the renter when a problem arises.
Condenser Housing
Cooling Coils
Heating Coils
Filter(s)
Outside Air Damper
Blower Fan
Supply Air Duct
FIGURE 16.1
Basic design schematic of rooftop air handling unit.
Return Air Duct
HVAC Systems
277
Centralized single unit distribution systems are zoned. Each zone will
generally have its own temperature controls. Yet if not properly designed,
zones can be problematic, especially as conditions change within each zone.
Inconsistencies may result as:
• Temperature requirements vary, within a zone, due to increased/
decreased occupancy in some areas or introduction of heat-producing
equipment (e.g., computers).
• Radiant heat gains and losses create uneven distribution of hot and
cold as the sun shifts during the day. This is a common cause of complaints in office building. On the west side, occupants complain it’s
too cold in the morning and too hot in the afternoon.
To further complicate and confuse, some level of awareness and knowledge
is prudent when assessing an HVAC system. A single HVAC system may
have one or several zones, each of which has its own temperature control
(e.g., thermostat), and each zone will have its own dedicated air distribution
box. The distribution boxes are sites where dust, air contaminants, and moisture can and do collect. Distribution boxes are briefly described as follows:
• Constant Air Volume (CAV)—varies temperature of the air delivered to the occupied spaces; temperature is regulated by controlling delivery of heated and cooled air to a mixing box for each zone
according to their requirements; and mixing box may collect, retain,
and distribute air contaminants.
• Variable Air Volume (VAV)—varies air volume delivered to the
occupied spaces as demand needs vary by zone; possible failure to
receive adequate makeup air as required by the American Society of
Heating, Refrigerating and Air Conditioning Engineers (ASHRAE)
Standard for Ventilation for Acceptable Indoor Air Quality.
• Hybrid Systems—the best and the worst of both CAV and VAV.
Last, but not least, air distribution is generally, not always, through air ducting. The duct may be insulated on the interior or exterior. It may be externally insulated flex or metal ducting. It may be fiberglass board that is itself
insulated. And the air supply duct in commercial units is often insulated
internally. Should there be leaks in the duct, air movement can draw outside
air (e.g., hot, dusty, insulated attic) into the air conveyance, delivering contaminants picked up along the way.
The complexity of HVAC systems is much greater than the simple description provided herein. The intent has been merely to cover the basics so the
investigator can visualize and conceptualize the possible impact a poorly
maintained HVAC system may have on indoor air quality. Should you wish
to become more enlightened, books on HVAC systems abound everywhere.
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HVAC Visual Inspection
The complexity of an HVAC system is such that there are multiple things that
can go wrong, multiple things that could contribute or add to building-related
health complaints. From stem to stern, inside the units and outside, the possibilities are endless. Herein is a discussion of a few of the possibilities.
They are only a start. Understand the system(s) and do not ignore oddities.
Investigate and consider all out-of-place items as part of the puzzle. The devil
is in the details!
Outdoor Air Intake
The outdoor air intake louvers should be checked. Some are manually
adjusted and most are computer-operated. It is not unheard of that the computer shows the louvers are open wherein upon inspection they are actually
closed. If not closed, the intake may be clogged. See Figure 16.2. Do not be
overly surprised to find a cardboard cut-out covering the air intake!
The air intake should ideally have an air filter that filters out the outdoor
air that mixes with the air return—after the return air has been filtered. In
other words, if the intake air is not filtered or minimally filtered (e.g., MERV 4
disposable fiberglass filter), most of the outdoor dust and debris will become
entrained in the HVAC system. As the U.S. Environmental Protection Agency
(EPA) National Primary Ambient Air Quality Standard for outdoor total
FIGURE 16.2
Rooftop air intake louver—open 100 percent with some collection of debris. (Courtesy of
Omega Southwest Consulting, Canyon Lake, Texas.)
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particles (75 µg/m3) exceeds the Leadership in Energy and Environmental
Design (LEED) acceptable limit for indoor total particles (50 µg/m3), clearly
unfiltered outdoor air can contribute to or be the source of poor indoor air
quality.
In commercial and high-rise office buildings, measure and calculate the
amount of outside air intake in terms of cubic feet per minute (CFM) per
person. The CFM per occupant should comply with the latest ASHRAE
Standard for Ventilation for Acceptable Indoor Air Quality.
Outdoor Air in the Vicinity of Air Intake
Investigate the area(s) around the HVAC air intake for bird (e.g., pigeon) and bat
droppings, garbage, leaves, and puddles of water. Locate sewer vents, kitchen
exhausts, chimneys, and cooling towers within the vicinity of the air intake.
There is no magic number to define “vicinity.” Use good judgment based on
wind patterns and suspect potential source of complaints and how they might
relate to times when the louvers are most likely to have been open.
Indoor HVAC Equipment Rooms
Many commercial HVAC units are located indoors in a room that also serves
as a return air plenum. It is astonishing how often one will find the same
rooms being used as storage for wet, dirty mops, paints, solvents, cleaning
fluids, oils, and other delightful surprises. Sometimes the investigator will
see something that just doesn’t look right. “If it looks out of place, it probably
is!” For example, a black stain was observed on top of and at the return entry.
It was directly under a fluorescent light fixture that was found to have burned,
emptying its product on the air handler. The light ballast contained PCB
transformer fluid that burned and blew the by-products onto surfaces within
the room that served as a return air plenum. See Figure 16.3. The by-products
of PCB combustion are among the most toxic chemicals known to man (e.g.,
polychlorinated dibenzofurans and polychlorinated dibenzodioxins).
Filters
Check the filter bank(s) for effectiveness. What does this mean? Look for gaps
between filters and around them. Air will follow the path of least resistance.
If it can, it will! Air will go around, not through the filter(s). In a filter bank
(e.g., multiple filters), the gaps/openings between the filters should be sealed
(e.g., aluminum or duct tape). Sometimes filters are installed improperly or
are not sturdy enough to withstand the air movement over the filter surface.
The result may be a deformed filter. See Figure 16.4. with a large volume of
unfiltered air!
Air filters should be inspected for cleanliness the have been recently
replaced, filters are not expected to be squeaky clean, but they should not
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FIGURE 16.4
Multiple filters in large commercial HVAC—deformed filter allowing unfiltered air to pass
through.
immediately after the filter. The residence had recently been crop dusted
with a powderlike pesticide that showed evidence that it had passed through
the HEPA filter and returned into the breathing zone of the residents. This is
an example of a filter “not performing” as intended.
The perceived efficiency of air filters does not always withstand a reality check. When asked about the efficiency of a filter in a commercial unit,
maintenance personnel will generally look up the efficiency that may say
the filter is 95 percent efficient, but looking further, the efficiency on the spec
sheet is based on a wide range of particle sizes. In reality, maybe the boulders
(greater than 10 microns in diameter) are captured, but the fine particles find
easy passage. The Minimum Efficiency Reporting Value (MERV) rating is
the most commonly accepted system and should be sought wherever possible. See Table 16.1. Not all filter manufacturers volunteer the MERV rating
within their specification sheets.
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FIGURE 16.5
Hospital bag filter—caked on dust/debris at upwind side with evidence of damage, mold
growth, and debris on the downwind side of the filter.
Condensate Drain Pan
Inspect the condensate drain pan. It should be free of standing water, or at
least it should be in the process of draining as the chilled water condensates.
If the air conditioning unit is not operating or there is standing water that
does not appear to be draining, either the drain is plugged or the drain pan
is not leveled to allow for drainage. See Figure 16.6. Standing water is a safe
haven for mold and bacterial growth.
In colder months when the heater is operating, evidence of poor water
drainage during the summer months is a rusted, dirty drip pan. Observe
the pattern of the rust. If drip pan level is a problem the rust stain will serve
as an indicator of that which was and that which will be again. Where the
rust is even, all the way to the top of the pan, there is or was likely a clogged
drain. Where the rust is uneven, away from the drain line, the pan is likely
not properly leveled.
In commercial units, maintenance often places biocide tablets in the drip
pan to minimize microbial growth. These are often dropped into the drip
pan and forgotten. Biocide tablets come with instructions. These instructions generally include a refresh/change schedule (e.g., monthly). They are
rarely read or followed. The presence of an empty container or deteriorated
HVAC Systems
TABLE 16.1
MERV Rating Summary
Residential Filters (MERV 1 to 4)
MERV 1 (e.g., self-charging woven panel filter)
Arrestance: 65%
Spot efficiency: <20%
Controls: carpet fibers
MERV 4 (disposable fiberglass or synthetic panel filter)
Arrestance: 75–80%
Spot efficiency: <20%
Controls: >10 microns
Commercial Filters (MERV 5 to 8)
MERV 5 (e.g., disposable synthetic panel filter)
Arrestance: 80–85%
Spot efficiency: <20
Controls: cement dust
MERV 8 (e.g., disposable extended surface area pleated filters)
Arrestance: 30–35%
Spot efficiency: >90%
Controls: 3.0–10.0 microns
Hospital Labs, Better Commercial, and Superior Residential Buildings (MERV 9 to 12)
MERV 9 (e.g., rigid cartridge filters 6 to 12 inches deep)
Arrestance: 40–45%
Spot efficiency: >90
Controls: welding fumes and auto emissions
MERV 12 (e.g., nonsupported microfine fiberglass or synthetic media)
Arrestance: 70–75%
Spot efficiency: >95%
Controls: 1.0–3.0 microns
Superior Commercial Buildings and General Surgery (MERV 13–16)
MERV 13 (e.g., rigid cartridge filters 6 to 12 inches deep)
Arrestance: 89–90%
Spot efficiency: >98
Controls: fine aersols such as sneezes
MERV 16 (e.g., nonsupported microfine fiberglass or synthetic media)
Arrestance: NA
Spot efficiency: NA
Controls: 0.3–1.0 microns
Carcinogenic, Pharmaceutical, Radioactive Materials, and Cleanrooms (MERV 17 to 20)
Note: Partial list, shows range of MERV ratings in each functional filter types.
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FIGURE 16.6
Residential HVAC—water staining around the base of the unit caused by overflow of drip
pan.
canister is an indication of acknowledged water excesses in the drip pan and
an easy fix in place of leveling the pan.
Fan Housing
The fan blades within the fan housing move the air. Subsequently, whatever air
passes through the HVAC will leave a forensic trace of all substances—large
and small. The fan belt deteriorates with time, and rubber particles are likely
to be a portion of the dirt and dust found on the fan blades and on the outside
of the housing. See Figure 16.7. The fan blades are a great collector of material
that can later be analyzed as if it were a crime scene. Follow the evidence!
Unit and Duct Liner
Chilled water blow-over to the downwind side of the HVAC unit is common
even in the best of units. A dust covered liner generally contains organic matter
(e.g., skin cells)—a meal for the molds; the liner gets wet—water for the molds.
The outcome is a feltlike carpet of growing mold. There have been report cases
of the happy meal deal wherein an investigator did not look at the HVAC
system. He/she found water penetration into the wall cavities of a building
with moisture and mold growth in the wall cavity, and stopped the search for
mold. Having found one source of mold growth, the environmental professional didn’t go any further. The investigator felt they had found “the cause”
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FIGURE 16.7
Fan housing—collection of dust and dirt from air.
of the elevated mold spores, ignoring the possibility that there may be multiple
sources, multiple causes, and the HVAC system is ignored.
A tragic example of an ignored HVAC is a 20-story office building where
the occupants were complaining of severe allergies. An environmental consultant investigated and found high mold counts in the occupied spaces and
moisture in the wall cavities associated with leaks in the caulking around
the marble exterior of the building. Remediation cost around $750 million,
and still complaints persisted. The consultant figured that the cause was
mold in the wall cavity that was escaping from around the wall sockets. So,
they persisted in monitoring the wall cavities with no definitive findings.
The mold counts still remained high. Another consulting firm investigated
the HVAC system and found a carpet of mold growth in the HVAC liner.
Corrective action was taken, and the indoor air mold counts dropped from
2000 counts/m3 to 200 counts/m3. Although there had been no remediation
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Indoor Air Quality: The Latest Sampling and Analytical Methods
FIGURE 16.8
Residential HVAC system—high humidity causing mold growth on unit liner and air supply
ducts.
on the monitored wall cavity, the fix on the HVAC liner was the silver bullet.
The complaints subsided!
Let’s go one step further. High humidity can wreak havoc on an entire
HVAC system. This occurs where there are no humidity controls or poorly
designed humidity management systems in a high humidity environment.
The evidence is different and distinct from chilled ware blow-over which is
generally limited to the water impacted areas of the liner. When high humidity is the culprit, all liner surfaces (e.g., bottom, sides, and top of the unit and
duct) will have a merry display of mold growth. See Figures 16.8 and 16.9.
Caution! Do not make the assumption that all ducting is affected. Whereas
the supply air duct is covered with mold growth, the air return may not be.
Inspect them separately!
Supply Registers and Return Air Grills
Supply registers are generally the telltale sign of problems from within or conveyance of contaminants through the HVAC system. Return air grills will usually have less of the same as that which is supplied and will be diluted down
as the air returns to the air handler. This scenario, however, is not an absolute.
Wherein it is drawing in contaminated air directly from the source (e.g., copy
machines), the air return grill may display more dirt than the air supply registers. The registers and grill are only signs. A deeper investigation is indicated!
In one instance, there was a disconnect, hole in the air duct through which
mineral wool insulation was drawn into the air stream, conveyed to the air
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FIGURE 16.9
Commercial HVAC system—high humidity causing mold growth on unit liner.
supply register. The appearance was that of gray dust monsters, swaying overhead from the registers. Black powderlike deposits are often interpreted by
occupants as the “black mold” wherein it may be shredded fan belt pieces.
Dirt around registers and grills are symptoms. See Figure 16.10. The
source(s) must be investigated. Contaminants are the clue, and sampling is
a must.
FIGURE 16.10
Dirty air supply register—water stain around edge.
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FIGURE 16.11
Mobile home HVAC unit—frozen chilled water line and condensate water draining through
the floor in the bottom of the unit.
Level of Maintenance
Evidence of poor HVAC maintenance should set off alarm bells. Some of the
signs include, but are not limited to:
•
•
•
•
•
•
•
•
Reduction in energy efficiency
Rips and tears in the liners
Dirty, clogged cooling coils
Frozen chilled water line (see Figure 16.11)
Used HVAC supplies (e.g., fan belts) left inside air handler
Dirty-and-beyond filters (see Figure 16.12)
Tools and equipment stored in an air handler
Rust, dirt, and debris buildup inside the units
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289
FIGURE 16.12
Wet, dirty filter—caked with dirt, debris, and mold growth.
•
•
•
•
•
Appearance of a slime or fuzzy growth
Dirt, damage, and moisture buildup
Condition of the fan belt and motor
Debris, dirt, and damage to the fan blades (e.g., broken fan blades)
Air deodorants in air supply systems (e.g., disguise odors)
Most residential and some commercial HVAC systems have filter(s) in
the return air grill. There is rarely a problem associated with the returns
unless they are forgotten and ignored. In an office building with strange
isolated niche areas of building-related health complaints, an enclosed
office where the occupant had severe health complaints was found to
have a return air filter that appeared never to have been changed. The filter was so old it had deteriorated to nothing more than a skeleton, a mere
thread of its original existence. Dust, dirt, and debris collected around
the old filter, and droppings were recycled, becoming part of the office
air quality.
Air Duct
Air duct conveys all that precedes it. If there is a problem upstream, it is
likely to be downstream.
There may be damaged, leaking air duct that could result in collection.
Leaking duct systems pick up contaminants along the way.
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The air duct to supply register connection may be loose or completely
detached. Air blowing in the space around the supply register could result in
condensation around the register or elevated dust levels from within the attic.
Sometimes the air duct is not just a conveyance for air but for varmints.
Rodents and rodent dropping have been found in air ducts. There was even one
report where an inspector went face-to-face with a snake—inside the air duct.
A homeowner saw a paw reaching down from one of the air supply registers.
Fearing the worst, brave soul that he was, he let it stay there until he could be
rescued by the professionals. They found a very hungry, very angry raccoon.
“Don’t be surprised at what might be lurking in them there air ducts!”
Strategy and Sampling
Most environmental professionals who investigate HVAC systems are searching for mold growth. Yet while mold growth is the most commonly encountered assailant in HVAC systems, there may be a worm or two in the pile.
Investigation is first and foremost. Seek and ye shall find. If something
looks strange and it can be sampled—sample it. If something looks out of
place and it can be sampled—sample it. If you think you know what it is and
it can be sampled—sample it.
Surfaces within and around the HVAC system may harbor suspect material. Whereas contaminants may be distributed into occupied air spaces, most
distribution substances will be growing on, deposited, and retained on the
surfaces. Thus forensic surface sampling, the simplest approach, is in order.
The most direct, easiest form of surface sampling is the “clear tape” method.
This approach involves the following:
• Dispense a 2- to 3-inch-long strip of clear tape (e.g., Moore Crystal
Clear).
• Loosely hold the ends of sticky side between your thumb and forefinger with sticky side facing out, away from your hand.
• Lightly touch, only once, the surface you want to sample. As some
samples are fragile—DON’T PRESS THE TAPE TO THE SURFACE.
Just touch the surface!
• Lift the tape and stick it to a surface for transport to a laboratory (e.g.,
thick plastic zip-lock baggie or microscope slide).
• Label the transport surface with an alpha/numeric identifier.
• Log sample location, identifier, sample date, and other pertinent
information (e.g., appearance, conditions, photo number, etc.).
• Fill out chain of custody information, and ship to a mold or forensic laboratory.
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291
A single lift represents quantifiable material (e.g., mold spores) per surface
area (e.g., square inch). Multiple lifts from several areas are used for identification only, but too much sample may obscure, obstruct analysis. So wherein
a larger sample size is required and the surface dust cannot be scooped up,
micro-vacuuming is another option.
Micro-vacuuming requires the use of an air sampling pump and filter. The
sampling pump acts as a miniature vacuum. The attached filter serves as the
vessel. This method is as follows:
• Using plastic tubing, connect a filter (e.g., polycarbonate, glass fiber,
or mixed-cellulose ester membrane filter) cassette to either a lowvolume or high-volume air sampling pump. FLOW RATE IS NOT
IMPORTANT. However, the higher the air flow, the better will be
the collection.
• Decide on the area you wish to sample, and create a template that
can be clean or discarded between samples. The most common template size is 4 inches by 4 inches (or 10 cm by 10 cm).
• Lay down the template and vacuum the area within.
• Label the cassette with an alpha/numeric identifier.
• Log sample location, area sampled (e.g., 100 cm2), identifier, sample
date, and other pertinent information (e.g., appearance, conditions,
photo number, etc.).
• Fill out chain of custody with the sample info and area information,
and ship to a mold or forensic laboratory.
The preceding sampling methods have been for surface sampling of relatively dry areas. For thick, caked-on, wet surfaces and for water samples
(e.g., drip pan water), bulk material collection may be collected in a vial. This
approach simply involves scooping up a sample into a collection container.
Protective latex or vinyl gloves should be used during the collection of any
material that you may contact with your hand (e.g., scooping up water).
Water samples should fill the container to the top and be sealed to prevent
leaks. Don’t withhold or limit the thick, caked-on samples, and collect at least
a teaspoonful. In a pinch, if you don’t have access to laboratory supplied
sampling vials, you may use a film container or unused medicine bottle and
seal them with electrician’s tape. The laboratory will weigh the sample(s) and
provide results in type of material per gram or measure the liquid weight or
per volume of liquid with results reported in term of material per ounce. Log
in the appropriate information, fill out the chain of custody, and ship to the
laboratory.
Last but not least, one may cut out a portion of the air handling unit interior lining or fiberglass duct. Cut it out or tear it out and place in a zip-lock
baggie or vial. Protective gloves should be worn, and all should be properly
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documented as in the preceding methods. Analysis will be reported in material per weight.
Analyzing the Unknown
The environmental professional will have speculated as to the possible component of material encountered in and sampled from within the HVAC system. More often than not, speculation will be the infamous “mold spores”
and mold growth. In this case, samples may be analyzed by one of many
mold laboratories. At that time, the samples should be analyzed for mold
spores and growth.
If, however, the investigator wants to go a little further, a forensic laboratory is in order. Many of the mold laboratories are able to identify most pollen
and some allergens in a generic sense. But if you want a better breakdown,
“forensic laboratories” can identify not only particles (e.g., fan belt rubber)
but sometimes chemicals that are adsorbed onto the surface of the particles
as well as metal deposits (e.g., deteriorating components), fibers (e.g., resin
coated fibers), animal urine, plant matter, and minerals. Forensic laboratories are a rare breed. So if a mold laboratory says they can perform forensic
analysis, let it be known that they are limited. A true forensic laboratory will
particle pick (or pick through the sample material under a microscope with
a very fine probe) and can identify all components. This is a very expensive
proposition and is often the last resort.
Then, too, if the investigator suspects a specific chemical or substance, the
surface sample (excepting the tape sample) can be analyzed by an industrial hygiene/environmental laboratory. This analysis is less expensive than
forensic analysis, but it fails to include “all possibilities.” All possibilities
may be an absurd effort in futility, while a narrow focus may be just what
the doctor ordered.
Interpretation Not So Simple
The mold spore and growth surface analysis is generally reported in terms
of amount and type of mold spores (less than 10 percent coverage) in a composite as well as amount and type of mold growth (e.g., 80 percent coverage
of Cladosporium).
As for other surface materials, the environmental professional may be
seeking confirmation or denial of a specific contaminant already identified in the air within the occupied area(s). There may be a witch hunt—if
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293
a previously identified contaminant is in the HVAC system, where is it?
How bad is it? Is it in the air supply? Is it in the air return? For instance, a
pesticide was crop dusted by an applicator inside a residence. A remediation firm cleaned all surfaces and furnishings, but they did not clean the
HVAC unit. Upon inspection, a fine white powder was found inside the air
handler immediately beyond a high efficiency box air filter. If the filter had
been operating as it should have been, the pesticide should not have gotten
through. There was a possibility that the white powder was sheet rock dust
from construction that got into the air handler prior to putting the filter in
place. The intent of the surface sampling had been to determine if the white
powder was a pesticide or sheet rock. The finding was that the powder was
indeed sheet rock dust.
Summary
This chapter speaks to inspections more so than sampling of HVAC systems.
Wherein the HVAC system is the single most conveyance of contaminants
in a building, it is all too often ignored or overlooked. Spend the big bucks
cleaning up visibly contaminated building materials, complaints temporarily
dissipate only to return with a vengeance. Why? The conveyor of all things
airborne has been overlooked. Always consider the HVAC system. A visible
inspection at the least should be conducted in order to identify anything that
just doesn’t look right. It is a terrible thing to boast that you have identified
and fixed a problem—only to find the problem still persists.
17
Sewage Systems and Sewer Gases
In the mid-1800s, London’s sanitary reform leader Edwin Chadwick commented, “All smell is disease.” Subsequently, the last half of the 19th century
was dedicated to designing drainage systems and “sewer traps” to prevent
the noxious gases from entering into homes. Societies further believed the
stench made people feel ill, lowering their resistance to disease—a predisposing factor to illness.
In 1881, after President James Garfield was shot by an assassin and taken
to the White House for treatment, a “well-known plumber” told a New
York newspaper that “the real trouble is sewer gas.” The unsanitary medical care Garfield received was considered a secondary cause in his eventual death eleven weeks later, two weeks after being moved to his New
Jersey home. The Sanitary Committee of the Master Plumbers of New York
offered to outfit the White House with sewer traps at no charge. Garfield’s
horrified successor, Chester Arthur, refused to move into the White House
until the plumbing was reconstructed to eliminate the sewer gas, going so
far as to insist the White House be torn down and replicated with a sewer
gas–proof replica in its stead—a project that would have cost $300,000
(nearly $7 million in today’s dollars). The Senate approved the expense, but
the House of Representatives refused. President Arthur had to settle for a
plumbing overhaul instead.
It wasn’t until the advent of the 20th century that public health officials
came out and stated that the danger of disease from sewer gases is “no
longer a plausible hypothesis.” Although sewage waste remains a concern
in regard to transmission of disease, the noxious gas is not thought to be
a carrier.
Plumbers had found a profitable niche in the building industry, and
despite advances in the 20th century, problems still rear their ugly head—in
old homes and in newly constructed residences. Yet the older the home, the
more likely sewer gases will arise to torment building occupants.
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Indoor Air Quality: The Latest Sampling and Analytical Methods
Occurrence of Sewer Gases
Raw sewage consists of everything flushed down the toilets and washed
down the drains. Residential sewage typically contains everything from
soap to human excrement, detergents, cleaning solvents, grease, food waste,
and any of a number of unknowns. Industrial and commercial sewage have
all that which is encountered in residential sewage and much more.
Hazardous Gases
The anaerobic decomposition of raw sewage in a septic system or sewage
line produces “sewer gases.” Sewer gases are predominantly hydrogen sulfide and methane—both flammable. Other gases include ammonia, sulfur
dioxide and nitrogen oxides. The “rotten egg” odor is generally associated
with hydrogen sulfide, but the noxious “sewage odor” can be a mixture of
hydrogen sulfide, ammonia, sulfur dioxide, nitrogen oxide, and occasional
unknowns.
Methane does not have an odor. It is not uncommon for building occupants say, “It smells like methane.” Why? They have been told there is methane gas in sewers. Some say, “It smells nasty.” Or, “It stinks.” Interpretation,
“It smells like sewage!” Yet sewer gases can be more than just an obnoxious
odor.
If allowed to decompose long enough in a confined space (e.g., clogged
sewer line or septic system), sewer gases can become an explosion hazard. For instance, there have been reports of septic cleanout operators
lighting a cigarette during the pumping process and receiving a flash
burn to the face as the flammable gases built up at the access hole. There
was one report of a homeowner who built a brush fire on top of his septic
tank that somehow resulted in a “sewer gas explosion” that rocked the
entire neighborhood.
Health complaints associated with sewer gases include nervousness, dizziness, nausea, headache, and drowsiness. Low-level exposure to the hydrogen sulfide gas component causes irritation of the eyes and respiratory tract.
Methane and carbon dioxide (by-products of bacterial degradation of sewage) are an asphyxiant (displace oxygen in air)—when encountered above
1 percent. This would be rare, occurring when gases have been trapped.
Ammonia, having a strong pungent odor, causes eye and mucus membrane
irritation. Sulfur dioxide and nitrogen dioxide are irritants as well. See
Table 17.1. The irritants are unlikely to be present in the sewer gases at any
significant levels so as to cause acute toxicity, but their odors will contribute
to the overall sewer smell along with all other nonhazardous odors associated with human waste.
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TABLE 17.1
Sewage Gas Exposures
Sewage Gases
hydrogen sulfide
ammonia
sulfur dioxide
Odor
Odor
Thresholda
(ppm)
1
rotten eggs
0.0045
25
pungent,
irritating
17
2
sharp,
irritating
2.7
ACGIH
TWA (ppm)
nitrogen dioxide
3
metallic
taste
bleach
nitrous oxide
(“laughing gas”)
25
–
a
0.12
– Low-Level Exposure
Warning Signs
irritation of eyes and
respiratory tract
irritation of eyes,
mucous membranes,
and skin
irritation of eyes,
mucous membranes,
and skin
upper and lower
respiratory tract
irritation
upper respiratory
tract irritation
Lowest accepted odor thresholds.
Biological Components
Sewage contains naturally occurring bacteria and microbial pathogens that
may pass through the alimentary system. The naturally occurring bacteria
are coliforms and E. coli. On the other hand, fecal pathogens are associated
with diseased people. They include a wide variety of bacteria, viruses, protozoa, and parasites. Although not generally airborne, many of these have the
potential for causing serious illness or death in infants, elderly people, and
immuno-compromised individuals if airborne exposures should occur in a
rare circumstance. For instance, sewage may backflow into or cross-contaminate an air handling system—unlikely, but certainly anything is possible!
Noxious Odor Confusion
Odors and health effects of sewer gases can be confused with mold and noxious chemicals within a structure. Sometimes there is no immediately apparent association between slightly detectable “stinky” odors and sewage such
as in a case whereby sewage gas leaked into an air duct and was dispersed
throughout the occupied space(s).
In an indoor air quality investigation, sewer gases are occasionally overlooked
especially when unpleasant odors are not emanating from a bathroom and the
occupant(s) are convinced the odor’s source is elsewhere. For this reason, sewer
gases should be considered wherein there is a complaint of “noxious odors.”
There are steps an investigator can follow when sewer gases are suspect.
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TABLE 17.2
Pathogens Encountered in Fecal Material
Bacteria
Gram negative bacteria may cause diarrhea, fever, cramps, and sometimes vomiting,
headache, weakness, loss of appetite, and other enteric symptoms. Some of the pathogenic
bacteria and diseases associated with fecal material include:
• E. coli (virulent and nonvirulent strains)—virulent E. coli infections result in severe
stomach tenderness and cramps, watery diarrhea (later bloody), nausea, and vomiting.
• Shigellosis—abdominal pain, fever, bloody stool, rectal pain, nausea, vomiting, and
watery diarrhea.
• Typhoid fever—rash “rose spots” on belly and chest, abdominal tenderness, agitation,
bloody stools, chills, confusion, difficulty paying attention, delirium, fluctuating mood,
hallucinations, nose bleeds, severe fatigue, lethargy, and weakness.
• Salmonella infections (most common foodborne illness)—diarrhea, abdominal cramps, and
fever.
• Citrobacter infections—associated with nosocomial infections, particularly in debilitated
patients, and in infants may cause meningitis and brain abscesses.
• Cholera—watery diarrhea (fishy odor), abdominal cramps, dry mucus membranes or
mouth, dry skin, excessive thirst, glassy or sunken eyes, lack of tears, lethargy, low urine
output, nausea, rapid dehydration, rapid pulse rate, unusual sleepiness or tiredness,
vomiting.
• Many others
Viruses
Hepatitis
Literally hepatitis means inflammation of the liver. Hepatitis caused by a virus is known as
viral hepatitis. When hepatitis is a result of sewage backup, it is often characterized by
inflammation of the liver and jaundice.
Protozoan
Cryptosporidium and giardia lamblia may cause diarrhea and stomach cramps, and even
nausea or a slight fever.
Parasites
Roundworm (ascariasis)—most people have no symptoms. With a lot of roundworms, you
may cough and have trouble breathing, or you may have pain in your belly due to a
blocked intestinal tract.
Investigation Procedures
Sewer gases can leak anywhere along the sewage lines and vents, get trapped
in the sewage system, and re-enter a building from outside. The cause and
source of complaint(s) may be multiple leaks, improperly or failed systems,
or they may be a single sewer gas leak in conjunction with other air contaminants disassociated from the plumbing. To address these complex issues, the
inspector may: (1) confirm and track sewer gases by air sampling; and (2)
perform a limited visual inspection for sewer system discrepancies.
Sewage Systems and Sewer Gases
299
Air Sampling
The components most frequently encountered in sewer gases are hydrogen sulfide and methane. Although is may seem fairly straightforward, air sampling
for the purpose of identification and tracking of sewer gases can lead to false
negatives, confusion, loss of time, and unnecessary laboratory expense. For
example, an inexperienced investigator rushed to the rescue where occupants
were complaining of sewer odors. He collected the noxious air in an evacuated
Summa® canister and sent it to a laboratory for analysis by gas chromatography/
mass spectrometry (GC/MS). This analytical method is not only expensive, but
it is a poor detector for both methane and hydrogen sulfide gas. Not only did he
inform the client that the laboratory told him that the “source” of the problem
was sewer gases, but he continued to insist that the odor was methane (which
without additives has no odor). The occupants were horrified as he persisted to
tell them methane was a “flammability hazard.”* Ultimately, he was able to track
down the sewage leak by destructive inspection of walls and ceilings with the
help of a plumber.
Many misunderstandings and much confusion can be avoided by simply
understanding the air sampling methods—not to be confused with tainted
Chinese drywall and natural gas leaks.
Natural gas is predominantly methane, and it is laced with low levels of an
odorous gas such as mercaptan gas that has a skunklike odor. Air sampling
may be performed for the purpose of identification and sometimes for tracking the source of a sewage system leak.
Identification of Components
Sewer gas confirmation can be accomplished by collecting air by evacuated canisters or ambient air sampling bags (e.g., Tedlar® bags). Analysis should then be
performed separately for the principal identifiers. The best recovery, most accurate analytical method for methane is GC/flame ionization detector (FID).
As for the hydrogen sulfide, laboratories may vary. EMSL analytical withdraws air from the canister or bag and analyzes the suspect air by using a
Drager Chip Measurement System (CMS) that has a 0.25 ppm detection limit for
hydrogen sulfide. This CMS, not an inexpensive piece of equipment, can also be
utilized for field grab sampling. Another approach, slightly more costly but having greater detection, is extraction of a headspace sample and analysis by GC/
SCD. The hydrogen sulfide detection by GC/SCD is 0.005 ppm. Each of these
combined analytical approaches is cheaper and more accurate than GC/MS.
Tracking Sewer Gases
Tracking hydrogen sulfide and methane gases may be accomplished using
a real time confined space entry monitor with both hydrogen sulfide (e.g.,
*
It takes days of sewage gas confinement for decomposition and off-gasing
sufficient to create combustible levels of sewer gases (e.g., methane).
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Indoor Air Quality: The Latest Sampling and Analytical Methods
photo-ionization detector) and combustible gas detection (e.g., Wheatsone
bridge). Although the odor of hydrogen sulfide gas is detectable at levels
much less than the detection of most field equipment, direct reading instruments can be helpful in “tracking” the source—if the source is producing
ambient hydrogen sulfide or methane levels in excess of the detection limits
for the instrument. The MultiRAE detection level for hydrogen sulfide is 1
ppm, and it is 1 percent of the LEL (Lower Explosive Limit) for combustible
gases (e.g., methane). Methane has an LEL of 5.5 percent. A measurement of
1 percent LEL methane would be 550 ppm.
Sewage System Inspection Awareness
Inspections are generally performed by a licensed plumber—if a leak is suspect. If, however, a leak is not suspected by the occupant(s), the experienced
environmental professional should be aware of the possibilities in order to
understand and track the source. All too often the bad odor association with
sewer gases and plumbing leaks/failures are not even considered for lack of
understanding as to the complex nature of plumbing problems. Air movement within a building is complex, and sewer gas leaks may not be blaringly
apparent.
An abandoned waste line may still be connected to the main waste line
and has not been capped off. In a crawl space or wall cavity, the sewage or
gases may enter the living space through wall or floor penetrations.
Drain waste vents and sewage lines may be clogged. Trapped gases may build
up and sewage may back up. Gurgling heralds a backlash of the “nasties.”
Re-entrainment of air from the roof vents and leaks/failures in septic/sewer
lines outside the building could enter a building through doors, windows, and
structural cracks. Re-entry into a structure may be caused by wind or heat.
Stories abound, things happen! A basic awareness of plumbing faults and
failures may add significantly an investigator’s bag of tricks.
Poorly Installed Sewer Vents
Sewer vents may be inadequate or missing. On the roof, a vent should be
vertical to the horizon, not to the roof. If a vent is sticking out of the roof at
an angle, something is wrong.
A plumbing vent should stick out above the roof, not on the side wall—next
to a window or door. If located anywhere than on the roof, it is not right.
Closed-off or blocked vents will result in sewer gas backups into a building. Blockage may occur due to the presence of wasp nests, birds’ nests,
rodents, and dead animals.
A plumbing vent may have all the appearances of having been properly
installed, but it may not be connected or improperly connected. Sewer gases
will then leak into the roof or wall cavity.
Sewage Systems and Sewer Gases
301
The fly-by-night plumber may not install any plumbing vents. With no
vents, sewer gases will re-enter through a sink or shower trap. If there are no
vents on a roof, be suspicious!
Then, too, some plumbers terminate plumbing vents in the attic or a wall
cavity. Not all structures, particularly in the country, are built to code. No
vents on a roof are a telltale sign.
Wherein too short above the roof, a plumbing vent is likely to get blocked by
snow and ice in freezing climates. Then, too, if it is of adequate height, the vent
may still get blocked when a lot of water vapor passes up the vent line (e.g.,
steamy showers). In both situations, the blockage is transient and will likely
dissipate when the weather warms up or when the ice melts in the hot sun.
Older buildings may have asbestos-containing transite plumbing vents.
What is the problem with this? The transite can delaminate and, with time,
clog the vent. Once again, sewer gases will backup due to blockage.
Plumbing Fixtures and Associated Traps
Associated with all plumbing fixtures, a “p” trap must be installed to prevent gases from backing up by retaining water in the angle to prevent gases
from returning. This is the case, as well, with the condensate water from an
air conditioning unit, particularly wherein the water drains into the septic/
sewer system. Sometimes there is either not enough space or the plumber
chooses to install an “s” trap or even a jerry-rigged car radiator hose (not to
code). These are poor at retaining water and poor seals to prevent sewage
gases from returning. If there is an “s” trap or some other strange fitting, be
suspicious. See Figure 17.1.
One of the most common problems encountered in indoor air quality
complaints and sewer gases is a failed “p” trap. When the water in the trap
evaporates and dries up, the gases return. This occurs mostly when a fixture
(e.g., toilet or shower) is not used on a daily basis such as guest bathrooms,
vacated homes, and unused shower stalls.
There have been reports of leaky, defective “p” traps, another source of
escaping sewer gases. A sign of leaks under a sink is the all too often found
water staining and mold growth—adding more full to the medley of odors.
Signs of leaks around a toilet base are staining or the “wobble effect.”
Staining is usually associated with a break in the wax ring seal. The wobble
effect is usually associated with leaks into the floor or ceiling below the toilet. It is referred to, herein, as the wobble effect, because the toilet moves
when lightly pushed.
In-Foundation Line Breaks
On occasion, there may be a break in the sewer line in the concrete foundation. If carpet is resting on top of the concrete foundation, the carpet may be
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Indoor Air Quality: The Latest Sampling and Analytical Methods
FIGURE 17.1
Commercial office space—under sink sewer line with no “p” trap and jerry-rigged plumbing.
unjustly implicated. To determine if there is an in-foundation leak, an investigator may use thermal imaging if the concrete is accessible (see Figure 17.2),
or a plumber can deploy a stealth camera to inspect the sewage lines from
within for cracks and leaks.
Septic/Sewage Drains and Lines
Besides the trademark sewer gas odors, signs of septic field failure involve
wet, soggy areas where the sewage effluent has risen to the surface. A
plumber can track failures in the septic fields by flushing a dye into the system. But generally the occupant will have addressed this concern prior to the
environmental consultant’s visit. The source of the odor is readily obvious.
Although not required by code, some plumbers place a sewer line vent
at the foundation, immediately outside the building. There are always cleanouts associated with a septic tank. All known or suspect potential cleanouts
should be inspected.
Interpretation of Results
Where hydrogen sulfide alone is encountered (without the presence of methane) the source may not be sewer gasses. It may be tainted Chinese drywall
or there may be another unidentified source of hydrogen sulfide gas. For
example, another source may be decaying organic matter in a compost pile.
Sewage Systems and Sewer Gases
303
FIGURE 17.2
Evidence of in-foundation sewer line leak—digital camera picture of area (left) and thermal
image camera picture (right).
Wherein methane alone is encountered (without the presence of hydrogen
sulfide) and there is an associated odor, the source may be natural gas. The
odor may be a mercaptan, not hydrogen sulfide. If there is a natural gas line
in or around the occupancy, a natural gas leak should be suspect and the
occupants vacated until the natural gas supplier can be contacted. This could
potentially pose a very dangerous explosive situation and should be acted
up immediately.
Confirmation of hydrogen sulfide and methane is significant to conclude
the culprit is sewer gas. A leak somewhere in the sewage system is suspect.
Tracking the source of the noxious sewer gases, using a real time monitor
(e.g., MultiRAE), and an awareness as to the potential sources of leaks just
may lead to the end of the rainbow—at least isolate the general area from
whence it came. It is highly unlikely that the investigator will get any real
time readings until he/she is next to or on top of the source. For example,
sticking the monitor intake into a drain that has a failed or defective “p” trap
will give a reading. Five feet away, there may be no readings at all!
Summary
Not all findings are the end-all, be-all to confirm or deny the presence of
sewer gases. All too often consultants have overlooked the possibilities due
to failed associations to toilet facilities (e.g., gas leaks in sewer vents in wall
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Indoor Air Quality: The Latest Sampling and Analytical Methods
cavities) or misdirection by the occupant (e.g., occupant associates noxious
odors with new furniture).
An awareness of the medley of discrepancies that may develop within
sewage systems can bring that which would otherwise be a dead end back
full circle to a possibility that would have been overlooked otherwise.
Confirmation of the worst case noxious air may be accomplished by evacuated canister or ambient air bag and laboratory analysis for hydrogen sulfide
and methane. Laboratory procedures and capabilities vary. Therefore, the
laboratory of choice should be consulted prior to sampling.
Sources may be tracked using field monitoring equipment with limited
detection limits. Detection limits are key to all proper sewer gas evaluations!
18
Tainted Chinese Drywall
In January 2009, Chinese drywall became suspect of causing unpleasant odors and possibly electrical problems in Florida homes. Residents
were complaining of health problems and declared their homes unlivable. Builders were accused of shoddy construction. Homeowners were
on the warpath claiming foul play. The Florida Department of Health
stated that “the levels of emissions from the drywall pose no immediate
health threat.” Environmental consultants also stated that there were “no
health threats.”
A huge uprising ensued. Insurance companies refused to pay on damages.
Lawsuits were filed. Many builders picked up shop and disappeared into the
dark of night. Lennar, the nation’s second largest home builder, responded
to the rising crescendo of unrest by replacing suspect drywall in some of the
homes, and still they were challenged.
In the meantime, in March, another battleground was forthcoming in
Louisiana. There were complaints, once again, of the drywall emitting a rotten
egg smell, causing respiratory problems, and corroding electrical equipment.
A couple in a suburb of New Orleans filed a lawsuit, this time against drywall
manufacturers. Knauf Plasterboard Co. Ltd. of China, a German-owned, drywall manufacturer, was identified as the biggest supplier of Chinese drywall
sent to the United States shortly after Hurricane Katrina in 2006.
By now, there had been 21 states throughout the United States and parts of
Canada that have made similar health and building claims associated with
the Chinese drywall. Most were in Florida, Louisiana, southeastern states,
and coastal Virginia.
By April 2009, The Associated Press indicated that “imports of potentially
tainted Chinese building materials exceeded 500 million pounds during a
four-year period of soaring home prices. The drywall may have been used
in more than 100,000 homes (built or) rebuilt after Hurricane Katrina in
August 2005.” Some speculate the problem may go back as far as 2001, but
the purchase and installation of Chinese drywall on a massively large scale
did not occur until the devastation that was wrought by the 2004 hurricane
in Florida.
As of October 2009, the Consumer Products Safety Commission had
“received about 1,501 reports from residents in twenty-seven states, the
305
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Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 18.1
States within the United States Confirmeda to Have Defective Drywall
Alabama
Arizona
Californiaa
Colorado
District of Columbiaa
Florida
Georgia
Georgiaa
Kentucky
Louisiana
Maryland
Michigan
Mississippi
Nevada
New Jersey
New Mexico
New York
North Carolina
Ohioa
South Carolina
Tennessee
Texas
Virginia
Washingtona
Wisconsina
Wyominga
Reported only, not confirmed.
Note: Puerto Rico and Canada also have confirmed reports of defective drywall.
a
District of Columbia, and Puerto Rico who believe their health problems or
corrosion of metal components in their homes are related to Chinese drywall. Many homes with Chinese drywall are unlivable, and some homeowners allege to have been driven to the point of bankruptcy.” As a result of
the drywall crisis, a group of U.S. senators called on the Federal Emergency
Management Agency (FEMA) to help homeowners, seeking rental assistance
for people who have had to leave their homes because of Chinese drywall.
As of March 2010, there had been no ban or recall on any Chinese drywall,
and Florida sought an emergency declaration for help with tainted Chinese drywall to allow homeowners and renters who have sustained uninsured losses to
receive financial assistance from FEMA and to receive stimulus grants from the
Obama administration to help repair homes that have Chinese drywall.
There is also an omnibus class action lawsuit filed by Parker, Waichman,
and Alonso LLP, against Knauf Plasterboard Tianjin Co. Ltd. awaiting trial.
Others named include, but are not limited to, Knauf’s parent company,
distributor(s), and importer(s). Lennar Homes has also filed suit, claiming it
“stands alongside its homeowners as a victim.”
With that said, homeowners appear to be the only parties filing complaints. Facility managers are either not affected or they are ignoring complaints lodged by building occupants. With the passage of time, the woes of
the homeowner may also be shared with facility managers.
Health Effects
An indoor air quality investigation may be sparked by any of a number of
concerns. There may be building-related health complaints and associated
odors. The building occupant(s) may have an expressed fear that they are
Tainted Chinese Drywall
307
victims of the “lethal” Chinese drywall gases, or they may have confirmed
corrosion or damage to their copper building materials. But in most cases,
building occupants experience health concerns.
The most common building-related health complaints associated with
tainted Chinese drywall are respiratory problems and eye irritation.
Respiratory problems could be coughing, sneezing, difficulty breathing,
bronchitis, and asthma. Many complain of nose bleeds and headaches, and
some complain of nausea, fatigue, sore throat, and runny nose—typical
allergy symptoms. Symptoms alone are not diagnostic!
Building occupants exposed to off-gassing from Chinese drywall are most
likely to complain of a rotten egg smell, and some have reported an odor reminiscent of burnt fireworks. Odor alone is not diagnostic! Yet in consort with
symptoms, the case strengthens. But there have been cases of no reported odors
in buildings where tainted drywall was encountered. Beware! Do not rush to
judgment if there is no associated odor. See Table 18.2.
TABLE 18.2
Summary of Interim Guidance—Identification of Homes with Corrosion from
Problem Drywall a
Threshold Inspection
Prerequisite positive response to both criteria for further consideration:
1. Blackening of copper electrical wiring or air conditioning evaporator coils.
2. The installation of new drywall (e.g., new construction or renovations) between 2001 and 2008.
Corroborating Evidence
If installed between 2005 and 2008, a home with characteristic metal corrosion problems
MUST also have at least two (2) of these corroborating conditions.
If installed between 2001 and 2004, at least four (4) of the following conditions must be met.
1. Corrosive conditions in the home, demonstrated by the formation of copper sulfide on
copper coupons (e.g., test trips of metal) placed in the home for a period of 2 weeks to 30
days or confirmation of the presence of sulfur in the blackening of the ground wires or air
conditioning coils.
2. Confirmed markings of Chinese origin for drywall in the home.
3. Strontium levels in samples of drywall core found in the home (i.e., excluding the exterior
paper surfaces) exceeding 1200 parts per million (ppm).
4. Elemental sulfur levels in samples of drywall core found in the home exceeding 10 ppm.
5. Elevated levels of hydrogen sulfide, carbonyl sulfide, or carbon disulfide emitted from
samples of drywall from the home when placed in test chambers using ASTM Standard
Test Method D5504-08 or similar chamber or headspace testing.b
6. Corrosion of copper metal to form copper sulfide when copper is placed in test chambers
with drywall samples taken from the home.
a
b
Federal Interagency Task Force on Problem Drywall: Interim Guidance (January 28, 2010) is a staff
document and has not been reviewed or approved, and may not necessarily reflect the views
of the Consumer Product Safety Commission or the Department of Housing and Urban
Development.
ASTM D5504-08: Standard Test Method for Determination of Sulfur Compounds in Natural Gas
and Gaseous Fuels by Gas Chromatography and Chemiluminescence (2008).
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Indoor Air Quality: The Latest Sampling of Analytical Methods
Screening Considerations
Many building occupants have been subject to media hype regarding Chinese
drywall. If they are experiencing any of the symptoms and have had recent
drywall installed in their home or office building, they are likely to seek
assistance. The health complaints may or may not be related to drywall, and
the fear generated by the media may encourage the homeowner or facility
manager to be safe rather than sorry.
As there is considerable expense involved in having a structure assessed,
some simple preliminary screening procedures have been offered by state
health departments, the Consumer Product Safety Commission, Housing and
Urban Development (HUD), and the U.S. Environmental Protection Agency
(EPA). The laundry list of federal, state, and local contributors is long, and
attorneys have varying opinions. But, in the overview, all basic homeowner
screening procedures are similar.
Homeowner Assessment
The Florida Department of Health developed a simple, online self-assessment guide that it recommended homeowners follow prior to a professional
investigation. See Table 18.3. If the homeowner answers “yes” to all the questions, he or she should seek the assistance of an experienced professional.
Inspection Screening
First, the experienced professional should attempt to confirm or deny the presence of Chinese sheet rock. This may be easier said than done! Although most
drywall is stamped with the manufacturer’s name (e.g., Knauf) or country (e.g.,
“Made in China”), the markings cannot be observed under painted surfaces.
However, in a finished-out residence, markings may be observed from the attic
(e.g., ceiling drywall), in the return air plenum, or any other place or means (e.g.,
TABLE 18.3
Step-by-Step Self-Assessment Guide for Home Owners1, 2
1. Was the house built after 2001?
2. Is there blackening of the air conditioning evaporator coils or repeated A/C evaporator
coil failure?a
3. Did you observe blackening or corrosion any of the following?
• Copper wires and electrical connectors
• Uninsulated and uncoated copper pipes and fittings
• Chrome-plated bathroom fixtures
• Silver and copper jewelry
• Mirror backing in bathrooms
a
Coil failures indicative of this problem typically occur every 6 to 14 months.
Tainted Chinese Drywall
309
borescope in drilled hole) where the backside of the drywall may be observed.
Then, to add insult to injury, there may be more than one manufacturer or
source. Beware a rush to judgment. A negative finding does not close the case!
Second, the professional should look for corrosion. Tainted Chinese drywall gives off corrosive gases that are trapped in wall cavities. The gases
corrode copper, silver, and chrome-plated metals, turning them black.
Unknown, unidentified corrosive gases build up inside the wall cavity, damaging exposed copper electrical wires and plumbing pipes not in the cavity,
but the gases leak out around wall penetrations and are pulled into the air
handler through the return air plenum.
Corroded electrical wires and cooling coils are likely to fail or be inconsistent. They should be placed at the top of the list of material and sites to
inspect. Check for black corrosion on the following:
• Copper plumbing under sinks, particularly around the wall
• Copper plumbing attachments behind dishwasher(s)/clothes washer
appliance(s), and water fountains
• Electric leads behind light switches and wall plugs
• Wall-mounted mirrors and decorative copper wall hangings
• Cooling coils inside air handling units
The HVAC return air passes though an air plenum that is generally enclosed,
surrounded by drywall. Wherein the drywall is tainted, the corrosive gas
emissions will be drawn into the air handler and pass through the copper
cooling coils. When this happens, the copper components start to corrode
and turn black. The conditioning unit slowly loses its efficiency and may fail
within 6 to 14 months. At this time, the drywall in the air plenum should be
suspicious.
Corrosion to exposed, uninsulated copper plumbing may leak and electrical wiring may fail. So drywall associated with plumbing leaks and electrical shorts/failures should be areas most likely to be associated with tainted
Chinese drywall.
Components of Chinese Drywall
Currently, isolation of unique components in Chinese drywall as compared
to U.S. drywall is a work in progress. Yet all researchers agree on one thing.
The elemental components of Chinese drywall are different from that of
U.S. drywall.
The EPA performed a limited study comparing drywall made in China to
that of domestic manufactured drywall. See Table 18.4.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
TABLE 18.4
Findings in U.S. EPA Study
Element
Made in Chinaa
(ppm)
U.S. Manufacturedb
(ppm)
2,570 & 2,670
1,390 & 1,630
244 to 1,130
841 to 3,210
Strontium (Sr)
Iron (Fe)
Note: ppm = mg/kg.
a Two samples analyzed.
b Four samples analyzed.
According to EMSL analytical, there is considerably more iron disulfide
and strontium sulfide in Chinese drywall than there is in U.S. drywall. It is
also alleged that the Chinese drywall has by-products from gas desulfurization plants—which adds even more sulfur to the mix.
The actual odorous gas(es) that cause(s) health effects and metal corrosion
remain speculative. They have yet to be confirmed! Yet the evidence seems to
point to hydrogen sulfide and other sulfur-containing components.
Hydrogen sulfide has a rotten egg odor, and it is also a by-product of
breakdown of iron disulfide and strontium sulfide—components of tainted
Chinese drywall.
FeS 2
SrS
high humidity/moisture
high humidity/moisture
→ H 2 S + other sulfur-containing gases
→ H 2 S + other sulfur-containing gases
Strontium sulfide is used in fireworks. Could this possibly be related to the
burnt fireworks odor?
The rotten egg odor is the most common complaint, but other odor complaints have been voiced as well. But all odor complaints seem to come full
circle to sulfur-containing gases. See Table 18.5.
TABLE 18.5
Sulfur-Containing Gases
NIOSH
REL-TWA
(ppm)
LD50
(mg/kg)rat
hydrogen sulfide
carbonyl sulfide
10
N/A
23
sulfur dioxide
carbon disulfide
2C
1
Gas
mercaptans
0.5C
Odor
rotten eggs
burnt fireworks
sharp, irritating odor,
metallic taste
medicinal
skunk
Note: C = ceiling exposure limit; 15-minute exposure.
Odor
Threshold3
(ppm)
0.0045
0.055
2.7
–
0.00073–
0.0000028
Tainted Chinese Drywall
311
The EPA claims the level of odor awareness for hydrogen sulfide is
0.01 ppm, and they recommend an 8-hour acute exposure guideline level
(AEGL) of 0.33 ppm. These are guidelines only, and the EPA does not offer
a guideline for homeowner occupancy and 24-hour exposures to hydrogen sulfide.
Some researchers have noted that not all Chinese drywall off-gasses sulfur-containing gases or causes corrosion, and not all corrosion is caused
by tainted Chinese drywall. Corrosion may be caused by sewer gases, well
water, and outdoor air contaminants (e.g., sour oil wells). On the other hand,
not all structures that have tainted drywall exhibit signs of corrosion. The
proof is in the analysis!
Sampling and Analytical Methodologies
Controversy reigns in the arena of the sampling and analytical methodologies. No two laboratories agree on a common approach. Yet, they do agree on
the basic principals and objective.
The objective is to determine: (1) if the suspect drywall is Chinese manufactured; (2) if it is off-gassing sulfur-containing gases; and (3) if it can cause
corrosion. The objective may be accomplished by two or three of the methods herein.
Bulk Sample Collection and Analysis
for Identification of Chinese Drywall
Although the sampling and analytical methods are a work in progress, all laboratory researchers agree on one thing—the mineral components in Chinese
drywall are different from that of U.S. drywall. The story ends here!
Sample Collection
Bulk samples are collected to confirm that suspect drywall is indeed “Chinese
drywall.” This may not be necessary wherein the Chinese-made drywall has
already been confirmed either by a visual inspection of the actual drywall or
records requested by legal council.
Identify worst case scenarios (e.g., around areas where corrosion has
been confirmed or areas that emanate the greatest odor). Cut (e.g., using a
drywall saw or drill-attached plug cutter) out a piece of the suspect drywall. The minimum cut-out bulk sample is a 2-inch diameter square (or
2-inch plug). However, wherein the investigator requires multiple samples of the same drywall for different analyses (e.g., headspace air sampling), a 1 foot square is suggested—unless indicated otherwise by the
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Indoor Air Quality: The Latest Sampling of Analytical Methods
laboratory. In light of the dickering about methodologies, the inspector
should seek directions from the preferred laboratory. Put the sample(s)
in a zip-lock bag, seal, label, and send to the laboratory with instructions
for analysis.
Sample Analysis
Analyses are highly variable. The most frequently encountered methods are
Fourier transform infrared spectroscopy and x-ray fluorescence.
Fourier Transform Infrared Spectroscopy
The Fourier transform infrared spectroscopy (FTIS) is a powerful tool for
identifying types of chemical bonds in a molecule by producing an infrared
absorption spectrum that serves as a molecular “fingerprint.” For drywall, it
can be used to quantitate components of an unknown and compare them to
that of a known mixture. See Figure 18.1.
Although FTIR has been used extensively in litigation, some say the method
is severely lacking, not providing an unimpeachable resource of information
and not identifying the actual source or cause of the health and corrosion
problems. The minimum drywall sample should be 4 inches by 4 inches.
X-ray Fluorescence4, 5
X-ray fluorescence, on the other hand, quantitates elemental components in
weight percent (wt%). See Table 18.6. Strontium and iron appear at a consistently higher level in drywall made in China as compared to that of the U.S.
The amount of drywall used is preweighed, and the wt% of strontium, iron,
FT-IR Comparison of Contaminated and Uncontaminated Drywall
3650
3150
2650
2150
1650
1150
Wavenumber (cm–1)
Uncontaminated
Contaminated Chinese
650
FIGURE 18.1
Sample Fourier Transform Infrared Spectroscopy. Courtesy of assured Bio, Oak Ridge, Tennessee.
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Tainted Chinese Drywall
TABLE 18.6
X-Ray Fluorescence Elemental and Chemical
Investigation
building materials
metals (e.g., Sr, Fe)
forensic science
geochemistry
ceramics
archaeology
glass
and other elements in the sample is reported either in terms of wt%, parts
of sample per million parts of drywall (ppm), or milligrams of sample per
kilogram of drywall (mg/kg). The latter are essentially the same (e.g., ppm =
mg/kg).
If limited material is available for analysis, dust samples and scrapings may
be microanalyzed by scanning electron microscopy/elemental dispersive
x-ray (SEM/EDX). The x-ray fluorescence approach appears to be the direction
taken by the EPA to differentiate drywall made in China verses the U.S.
Suspect Air and Headspace Sampling for Off-Gassing Components
Allegedly, not all Chinese drywall is tainted. Apparently, the laboratories
are unable to get all confirmed Chinese drywall to off-gas hydrogen sulfide
or other corrosive gases. So sulfide gases are the first step to confirming or
denying that suspect drywall is tainted.
Initially, investigators attempted grab air sampling in the occupied spaces—using colorimetric detector tubes. Many investigators used the detector
tubes for hydrogen sulfide gas that has a detection limit of 0.2 ppm, which
is above the odor threshold (e.g., 0.0045 ppm). Some attempted to use direct
reading instrumentation (e.g., photoionization detector confined space entry
monitor). Detection was no better!
So there has been a concerted effort to attain greater sample collection efficacy and higher analytical detection limits. Yet at the extreme low-level analytical detection limits desired, improperly collected samples can be misleading.
Sample Collection
One approach to onsite air sampling may be performed sampling the air
from within a wall cavity. The inspector should speculate as to the worst
case scenario, worst case wall cavity. Punch or create a hole large enough
to stick a “glass extension tube” or stop cock of a preconditioned evacuated
canister or ambient air sampling bag (e.g., Tedlar® bag) into the wall cavity
and collect a wall cavity air sample. The ambient air sample bag should be
preflushed onsite with the same air that is to be tested. After collecting the
air sample, close the stop cock or valve, label, and send to the laboratory for
analysis by GC/MS or GC/SCD.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
A more recent approach to on-site air sampling that will permit air sampling within the occupied space is the use of a Test America custom-made
passive monitoring canister. The monitor is to be placed in an open area
where it collects hydrogen sulfide gases over an extended period of time—up
to one week. After the collection is completed, the container can be sealed,
labeled, and sent to the laboratory for analysis by GC/SCD.
A bulk sample is the simplest, most reliable approach—if the sample site
has been chosen well! Take a minimum 6-inch by 6-inch bulk sample of suspect drywall. Put it in a zip lock bag seal, label, and send to the laboratory
with instructions for headspace analysis by gas chromatography/mass spectrometry (GC/MS) or GC/sulfur chemoluminescence detector (SCD).
In all instances, an unexposed control should accompany each set of samples—both inside and outside the laboratory. Cross-contamination by preexisting ambient sulfides could find the lab or investigator in a quagmire as
to how best to interpret unimpeachable results. Although not requested or
required by most laboratories evaluating Chinese drywall, a blank can minimize speculation as to the samples efficacy.
Sample Analyses
Laboratory instrumentation gets greater detection limits than field colorimetric tests. The approach is still evolving as laboratories gain greater expertise.
Gas Chromatography/Mass Spectrometry (GC/MS)
Initially, GC/MS analysis of gas/chemical compounds with an emphasis on
sulfide gases was the analytical method of choice—samples having been collected onsite or in the laboratory as bulk sample/headspace air samples. The
sulfide detection level is 20 ppb. This was considered a great improvement
over the detector tubes, but still, the odor threshold of hydrogen sulfide (e.g.,
4.5 ppb) is lower that the GC/MS is capable of detecting.
Gas Chromatograpy/Sulfur Chemoluminescence Detector (GC/SCD)
Gas chromatography/sulfur chemoluminescence detector is a method
similar to GC/MS. Only instead of the GC/MS characterization and identification of gas/chemical compounds using an extensive computer library
of gas-chemical characterization and identification, the GC/SCD looks at
sulfur-containing compounds only—using standards for identification. The
GC/SCD detection limit for sulfur-compounds is 5 ppb, more powerful than
that of GC/MS, and GC/SCD is less expensive.
In the laboratory, ALS Laboratory Groups has compared results of the
same lot of drywall both with high humidity and without. The findings
were a surprise! Hydrogen sulfide levels have been 10 percent less when
presented with high humidity than with low humidity. This appears to be
contrary to the consensus that off-gassing of corrosive gases occurs most
always in high humidity environments.
Tainted Chinese Drywall
315
FIGURE 18.2
Corrosion testing in temperature controlled incubator (top) and results (bottom). (Courtesy of
EMSL Analytical, Cinnaminson, New Jersey).
Corrosion Testing
All laboratories go for the corrosion test. After all, corrosion testing is the
coup de grace, the nail in the coffin, for identifying tainted Chinese drywall.
The goal is confirmation that onsite observed copper corrosion was caused
by suspect drywall from the vicinity of the blackened copper. The approach
varies between laboratories, but the basic premise is the same.
Sample Collection
Bulk samples are analyzed by a laboratory. The collection approach should
be similar to that described under the section on “Bulk Sample Collection for
Identification of Chinese Drywall—Sample Collection.”
Copper Pipe 7- to 14-Day Incubation
At EMSL, a copper pipe is installed within a 2-inch by 2-inch sample of drywall and placed in a glass jar at a temperature of 99 to 100°F and 90 percent relative humidity. The condition of the copper is monitored over a 7- to
14-day time period. After 2 weeks, the extent of corrosion is observed where
the copper pipe was touching the drywall and around the penetration point.
This method does not provide the cause of the corrosion, but does confirm
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Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 18.3
Corrosion Test of Copper Discs (environmental chamber with temperature, humidity, and
pressure maintained throughout the test)— corrosion resulting from tainted drywall (left) as
compared to no corrosion (right). (Courtesy of Assured Bio, Oak Ridge, TN.)
that it is tainted. Then, EMSL goes one step further and performs an SEM/
EDX microanalysis of scrapings from the corroded copper to determine if it
is sulfur-related.
Another, more “aggressive” approach involves:
•
•
•
•
•
Remove the paper from the drywall sample—front and back
Sand the surface of the exposed drywall—allegedly to “activate”
Direct contact flat copper to the activated surface of the drywall
Enclose and maintain contact for up to 14 days
Check for corrosion
As some people suspect poorly processed Chinese paper as being a likely
source of sulfide gases, the aggressive approach eliminates that possibility.
There is no standardized procedure for corrosion testing. There seems to
be as many different approached to corrosion testing as there are laboratories that perform the services. See Figure 18.3.
Copper Wire 48-Hour Incubation
At ALS Laboratory Groups, a stripped copper wire is installed in a glass
jar along with a 2-inch by 2-inch sample of drywall and heated for 48
hours. The lab does not increase the humidity when testing for corrosion.
The condition of the wire is then evaluated for corrosion and tarnishing
within 48 hours.
Microbiological Testing
Drywall in landfills produces sulfur gases—in particular hydrogen sulfide.
Under anaerobic (lack of oxygen) conditions, moisture, and sulfur-reducing
Tainted Chinese Drywall
317
bacteria, drywall (about 90 percent CaSO4 and 10 percent paper) produces
hydrogen sulfide. An attempt to duplicate this process in laboratories has
met with poor results, and the chemistry is nonspecific. This test procedure
is an option that appears to provide—no useful results.
Interpretation of Results
The investigation’s objectives are to confirm the presence of tainted Chinese
drywall. Sampling and analysis are threefold. Laboratory analyses can confirm suspect drywall to have been made in China, to be off-gassing sulfurcontaining gases, and to cause copper corrosion.
Chinese Manufactured Drywall
Literature abounds with information regarding components of Chinese drywall as compared to that which was manufactured in the U.S. Yet there is
consistency regarding the element of strontium. Whereas the domestic levels of strontium range from 244 to 1130 milligrams per kilogram (mg/kg),
Chinese drywall has levels greater than 2570 and sometimes as high as 5000
mg/kg.6, 7 And high levels of strontium appear (not conclusively confirmed)
to be associated with copper corrosion. So high levels of strontium are a
strong indicator that the sample is Chinese drywall.
Fingerprint comparison by FTIS has been used in litigation, but the technique is coming into question. The purpose is simply to compare and is not
a stand-alone approach to confirming or denying the presence of Chinese
made drywall. Once again, not all Chinese drywall off-gases noxious odors
that causes health problems or corrosion.
If selected from the vicinity of known corrosion, a sample is more likely
to represent a worst-case scenario whereby a negative finding is significant in determining that Chinese drywall is not present. Positive findings
are significant.
On the other hand, a negative finding of a random sample (such as one
taken for a convenient site on a wall) that is not associated with corrosion
may indicate nothing more than that specific sample may not be tainted. So,
the plot thickens!
Off-Gassing Sulfur-Containing Gases
Not all Chinese drywall is tainted, resulting in off-gassing of sulfur-containing gases and causing corrosion. By the same token, not all tainted
drywall results in off-gassing within every wall cavity. Was the complaint
lodged prior to the time required for corrosion to develop (e.g., immediately
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Indoor Air Quality: The Latest Sampling of Analytical Methods
after installation)? If a year has passed since drywall installation and there
has been no observed corrosion, were the conditions such that the drywall
would have off-gassed? Conditions not conducive to off-gassing are low
humidity (e.g., a year of drought) and cooler temperatures (e.g., north central
U.S. climate). So the question remains, “Is the confirmed Chinese drywall
tainted, able to cause corrosion?”
Air samples and corrosion testing are the end run. If corrosive hydrogen
sulfide gas is confirmed by colorimetric detector tube (poor detection), GC/
MS (moderate detection), or GC/SCD, the drywall is tainted.
Whereas some laboratories diverge from hydrogen sulfide as the indicator gas, ALS laboratory groups has found that all drywall, Chinese and
domestic, will give off carbonyl sulfide and carbon disulfide. Sulfur dioxide
and methyl/ethyl mercaptans were not present in any of the samples. Only
Chinese drywall gives off hydrogen sulfide!
ALS laboratory group has speculated that the source of the carbonyl
sulfide and carbon disulfide are paper. They have performed analyses of
paper products both from drywall paper backing and cardboard. Both have
been demonstrated to off-gas carbonyl sulfide and carbon disulfide. Thus
although the mechanism is unknown, Chinese drywall exclusively gives off
corrosive hydrogen sulfide. This approach alone may circumvent and singularly prove that the drywall is Chinese made—cut down on the number of
samples and on the analytical cost(s).
Causes Corrosion
If copper corrosion or tarnishing is demonstrated, the drywall is likely
tainted. Confirmation of sulfur in the corrosion by means of SEM/EDX
microanalysis is a more powerful case leading to tainted Chinese drywall.
Summary
The 2009 Florida debacle with tainted Chinese drywall was the beginning of a maelstrom of litigation that has spread nationwide and impacted
thousands of homes. Early on, environmental consultants and the Florida
Department of Health had been sent on a witch hunt to find the culprit that
was the source of sulfurlike noxious odors, health complaints, and corrosion
of copper building materials.
As Chinese drywall appeared to be the bane of all the complaints, there
was a rush to develop a means to evaluate the suspect drywall. As there was
no established methodology, diverse sampling and analytical procedures
evolved. The source was known, but the actual component that causes the
problems remained, and still remains, unknown. Many will speculate, but as
Tainted Chinese Drywall
319
no one has conclusive evidence, sampling and analytical methods can only
focus on findings that seem to be consistent with problem residences.
Homeowner self-assessment screening guides generally consisted in aiding those in suspect residences. Investigators, too, have developed a presample screening process. The components of Chinese drywall have found
common ground as compared to U.S. drywall. Sampling and analytical
methodologies are consistently similar in intent and dissimilar in procedure.
No one method is perfect, but they get the job done. In brief, once again, the
following questions must be answered:
1. Is the suspect drywall Chinese manufactured? Unless requested
by the client or lawyer, the experienced professional may skip this
question and go on to Item 2.
2. Is the suspect drywall off-gassing hydrogen sulfide?
3. Is the suspect drywall causing corrosion?
References
1. Florida Department of Health. Self-Assessment Guide for Signs That a Home May
Be Affected by Drywall. Retrieved from www.floridashealth.org/Environment/
community/indoor-air/drywallFAQ.html (May 2009).
2. Florida Department of Health. Case Definition for Drywall Associated Corrosion
in Residences. Retrieved from www.doh.state.fl.us/environment/community/
indoor-air/casedefinition.html (December 18, 2009).
3. AIHA. Odor Thresholds for Chemicals with Established Occupational Health Standards.
AIHA Press, Fairfax, Virginia (1997).
4. Spates, W.H., III et al. Evolution of Chinese Drywall Inspections and Findings Based
on Laboratory Data, FDOH Guidelines and the Need to Incorporate New and Productive
Inspection Techniques. Indoor Environmental Technologies, Inc., Clearwater,
Florida (2009).
5. Rajiv, R.S. Chinese Drywall Testing Guidance for Residential and Commercial
Buildings. Real Estate News, Tampa, Florida (February 15, 2009).
6. Spates, W.H., III et al. Evolution of Chinese Drywall Inspections and Findings Based
on Laboratory Data, FDOH Guidelines and the Need to Incorporate New and Productive
Inspection Techniques. Indoor Environmental Technologies, Inc., Clearwater,
Florida (2009).
7. Rajiv, R.S. Chinese Drywall Testing Guidance for Residential and Commercial
Buildings. Real Estate News, Tampa, Florida (February 15, 2009).
19
Green Buildings
It is alleged by the U.S. Green Building Council that green buildings can
reduce energy consumption by 26 percent and that retrofitted existing buildings may reduce energy usage as much as 30 to 40 percent.1 New York City
and Washington, D.C. require all new construction be “green” certified. In
December 2009, Mayor Michael Bloomberg of New York City attempted to
impose mandates that existing buildings go green and failed. Other municipalities have also tested the firestorm of public opinion for mandating green.
And there has been a lot of push back!
Opponents claim the cost for going green will increase construction costs
10 to 20 percent. According to the Green Building Finance Consortium, a
Leadership in Energy and Environmental Design (LEED) Platinum rating
will result in higher initial costs of 11.5 percent for new construction.2 The
proponents of green suggest the construction costs will diminish with
time, and energy savings will offset the increased costs.
Retrofitting existing buildings requires even greater expense. For example,
all single pane aluminum windows must be replaced by double pane vinyl
windows which, irrespective of building size, can be extremely expensive,
and window replacement is only the beginning.
The intent of going green is to create a more energy efficient, environmentally friendly indoor air environment. In the past, energy efficiency was
synonymous with a tight building. Tighter is better! Closing in and sealing
up buildings in occupied, conditioned air spaces lead to trapped emissions
from building materials, furnishings, and other products. Tight buildings
resulted in “sick building syndrome.”
In the 21st century, “green” is being redefined. The champions of green
now seek to certify green buildings as those that have minimal impact on the
environment and are healthy for building occupants. The playing field has
changed. Health and indoor air quality must work in consort with energy
efficiency. This is where the environmental professional has a defined proactive role to play.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
21st Century Green
In 1998, the U.S. Green Building Council developed technical criteria for certifying green building construction. The program comes under the heading
of LEED—a purely voluntary, market-driven approach to rating energy efficient, environmentally friendly building designs. It does not have the force
of law! The driving force is energy cost savings, increased resale value, and
resource conservation.
Having originated in the United States, the LEED Certification Program
is beginning to go global. State and local governments are adopting the program for public-owned and public-funded buildings, and there are initiatives
in federal agencies. For example, the U.S. General Services Administration
mandates that all new projects and renovations on nonmilitary government
construction must meet the minimum LEED standards.
Privately owned buildings and residences are engaged as well. Homeowners
are a hard sell in hard times, but some of the wealthier homeowners are
engaged and motivated to incorporate green into their home designs. One
homeowner with a Platinum Certification commented, “My wife and I are
committed to going green and doing the right thing. In terms of the building
design, saving resources, and setting an example for our colleagues and our
children.”
Privately owned buildings that currently are LEED certified include hotels
(e.g., Proximity Hotel in North Carolina), small businesses (e.g., Office Depot in
Austin, Texas), large businesses (e.g., L.L. Bean in Mansfield, Massachusetts),
commercial buildings (e.g., One Boston Place in Boston, Massachusetts), and
banks (e.g., Banner Bank Building in Boise, Idaho). Libraries, schools, and
retail stores have also been certified.
The LEED proposes a comprehensive strategy for optimizing indoor air
quality and minimizing potential problems. This strategy had become the
“gold standard” for ensuring good indoor air until the recent publication
of the American National Standards Institute/American Society of Heating,
Refrigerating and Air Conditioning Engineers (ANSI/ASHRAE) Standard
189.1.
In 2009, ANSI and ASHRAE proposed ANSI/ASHRAE Standard 189.1,
“Standard for the Design of High-Performance, Green Buildings—Except
Low-Rise Residential Buildings” (ASHRAE Standard). Its stated purpose
is to “provide minimum requirements for the sitting, design, construction,
and plan for operation of high performance green buildings … to balance
environmental responsibility, resource efficiency, occupant comfort and
well being, and community sensitivity.” In other words, the Standard is
similar to the LEED Certification Program with muscle—exclusive of lowrise residential buildings.
Green Buildings
323
LEED Key Performance Areas for Residential3
(Points Possible/Minimum Points Required)
Sustainable Site Development (22/5)
Water Savings (15/3)
Energy Efficiency/Energy Star and Atmosphere (38/0)
Materials, Resources, and Waste Management (16/2)
Indoor Environmental Quality Management (21/6)
Innovation and Design (11/0)
Awareness and Education of Owner(s) (3/0)
Location, Access, and Neighborhood Development (10/0)
Certification Thresholds
• Certified: 45.0 points
• Silver: 60.0 points
• Gold: 75.0 points
• Platinum: 90.0 points
The Standard does not apply to single-family residential structures, multifamily structures (i.e., less than three stories high), manufactured homes, and
buildings without utilities. It is a standard, not a guide, and it does not afford a
rating system. The rating system remains a management tool of the LEED.
Both the LEED and ANSI/ASHRAE Standard 189.1 have a provision for
building flush-out* and for preoccupancy air monitoring. Hence, the environmental professional is called upon to confirm a healthy environment in
“green buildings.”
Green Flush-Out Protocols
The LEED approach to assuring good indoor air quality is neither mandated nor strongly suggested in all occupied buildings where certification
is desired. The ANSI/ASHRAE Standard 189.1 goes the extra mile and mandates postconstruction activities and air monitoring in high performance
buildings only, and compliance may be required by the building owner(s).
Both the LEED and the ASHRAE Standard are voluntary, best-practice directives for healthy indoor air quality.
*
Flush-out is a reference to the replacement of all indoor serviced air by the outdoor air. The
flush-out rate is the volume of outdoor air required to replace the same volume of indoor air
for each area serviced.
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Indoor Air Quality: The Latest Sampling of Analytical Methods
LEED Indoor Air Quality Management Plan
Upon completion of construction, LEED recommends a building be flushed
out. A building flush-out involves turning on the air handler with the
makeup air fully opened. They suggest a postconstruction, preoccupancy
flush-out of 14,000 CFM/ft2 while maintaining an internal temperature of
at least 60°F and no higher than 60 percent relative humidity. The process
may take as much as two weeks or more depending upon the capacity of
the air handler(s).
An alternative flush-out* schedule may be invoked if time is an issue. A
postconstruction flush-out of 3,500 CFM/ft2 as allowed prior to occupancy,
but the full 14,000 CFM/ft2 flush-out must be completed in order to obtain
certification points. Yet delayed occupancy or costs for conditioning the air
in early occupancy can have negative consequences. The alternative to a
complete flush-out is air testing.
The required flush-out may be reduced or eliminated entirely wherein
air sampling is performed, and measured parameters are below LEED prescribed limits. The parameters are formaldehyde, total volatile organic compounds (VOC), carbon monoxide, and 4-PCH.
ANSI/ASHRAE Standard 189.1—Construction and Plans for Operation
In accordance with ASHRAE 189.1, the HVAC system(s) shall remain covered, clean, and nonoperational during construction. After construction
ends, prior to occupancy and with all interior finishes installed, a postconstruction, preoccupancy building flush-out or optional baseline air monitoring is performed.
The Standard mandates a building be flushed in accordance with minimum prescribed limits as defined by a formula:
TAC (total air changes) = V × 1/A × 1/H × 60 min/h × 24 h/day × 14 days
V = outdoor air intake flow (CFM)
A = floor area (ft2)
H = ceiling height (ft)
The flush-out shall be continuous and the supplied outdoor air rate shall be
no less than the design minimum, unless occupancy is desired prior to completion of the flush-out. Wherein occupancy is desired prior to completion of
the time required for minimal air exchanges, the space(s) may be occupied
after half the minimum has been met and after air sampling compliance.
*
Flush-out is a reference to the replacement of all indoor serviced air by the outdoor air. The
flush-out rate is the volume of outdoor air required to replace the same volume of indoor air
for each area serviced.
Green Buildings
325
Baseline air sampling must not be conducted prior to 24 hours after the
designed outdoor air flow rate has been established—for each HVAC service
area. One set of breathing zone samples should be performed for each HVAC
service area. More sample sets are required should an HVAC service area
exceed 25,000 ft2 or greater than one contiguous floor area.
If a sample set exceeds the maximum concentration limits, additional
flush-out with outside air is required and a retest performed afterwards for
the specific parameter(s) exceeded in the initial testing. Repeat the process
until all requirements have been met. Retests should be performed at the
same locations as previous test sets.
Biannual monitoring is required thereafter by at a minimum of one of
the following:
1. Air monitoring at previously prescribed sites.
2. Monitoring occupant perceptions of indoor air quality by any
method, including, but not limited, to occupant questionnaires.
3. Occupant complaint/response program for indoor air quality
complaints.
Annual air testing of all sites is recommended minimally for those contaminants that tested marginal on the postconstruction sampling.
Each sample set consists of formaldehyde, carbon monoxide, 4-PCH, specific identified volatile organic compounds, particulates, and ozone. If there
is no carpeting in the building, 4-PCH may not be required. 4-PCH has been
associated only with rubber backed, wall-to-wall carpeting.
Sampling and Analytical Methodologies
The LEED program does not ascribe to strict air monitoring procedures, and
the LEED parameters are similar to, but less restrictive than, the ASHRAE
Standard parameters. Both programs define limits for formaldehyde, total
VOCs, 4-PCH, particulates (PM 10), and carbon monoxide. The ASHRAE
Standard further requires identification of up to 29 additional organic compounds (formaldehyde and 4-PCH are included in the list) and PM 2.5 (along
with PM 10). The sampling methods for each contaminant group (i.e., particulates, carbon monoxide, formaldehyde, 4-PCH, and VOCs) are different.
Particulate sampling may be accomplished by direct reading, data logging
particle counter with mass display and by sample collection. See Figure 19.1. For
LEED, the particle counter must be capable of measuring all particle sizes less
than 10 microns (PM 10) to a total mass below 50 microns/m3 (µg/m3). For the
ASHRAE Standard, it must measure particle size less than 2.5 microns (PM 2.5)
as well as 10 microns to total mass below 35 microns/m3, and monitoring must be
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Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 19.1
MetOne Aeroset 531 Particle Counter—mass monitor and particle counting (Courtesy of
MetOne, Grants Pass, Oregon.).
performed for 24 hours. There are no time requirements for LEED. Forewarned,
the particle counter does not rely on actual measured weight but on projections
and calculations (e.g., average weight per particle size).
LEED—PM 10 reading to below 50 µg/m3
ASHRAE Standard—PM 2.5 and PM 10 reading to below 35 µg/m3
On the other hand, sample collection is based on actual measured weight.
Yet sample collection produces only one number—total weight/m3. The particle counter has the benefit of multiple data points.
In simple terms, the particulate air samples are collected on a filter that is
later weighed and results calculated by a laboratory on the basis of the sample
air volume reported by the environmental professional. Now, to attain PM 2.5
or PM 10, a size-selective particle sampler is required. For example, a personal
modular impactor (PMI) and personal environmental monitor (PEM) have
machined holes that limit the particle size entry and impaction onto the filter.
Green Buildings
327
A different sampler is generally required for each particle limit (e.g., PM 10)
and, in some cases, for desired flow rate. A different PEM sampler is required
for different flow rates (i.e., 2, 4, and 10 liters/minute). For the PMI, the flow rate
is 3 liters/minute with no other choices available. The following is:
• Sampling equipment: air sampling pump, size-selective particle
sampler (e.g., PM 10 and PM 2.5 PMI impactor). See Figures 19.2
and 19.3.
• Bounce reduction: oiled-impaction disks (e.g., PMI) or oiled impaction ring (e.g., PEM).
• Collection medium: 37 mm PTFE filter or 37 mm Tissu Quartz filter.
• Flow rate(s): variable, impactor dependent (i.e., SKC personal modular impactor—3 liters/minute).
• Sample duration (based on flow rate of 3 liters/minute): minimum of
3.3 hours (LEED); 24 hours required (ASHRAE Standard).
• Detection limit(s): 50 µg/m3 (3.3 hours); 7 µg/m3 (24 hours).
• Analytical method: gravimetric.
FIGURE 19.2
PMI for PM 10 (Courtesy of SKC, Eighty Four, PA.).
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Indoor Air Quality: The Latest Sampling of Analytical Methods
25-mm Impaction
Substrate
Filter Cassette Top
Filter Cassette Bottom
PM2.5 Inlet (Coarse Ring)
25-mm Filter in Impaction
Substrate Position
Filter Cassette Top
37-mm Final Collection Filter
Support Screen
Filter Cassette Bottom
Exhaust
FIGURE 19.3
Breakdown of a personal modular impactor—PMI course includes PM 10 and PM 2.5 in same
unit (Courtesy of SKC).
Green Buildings
329
With the sample time and laboratory analytical turnaround time, sample collection is considerably more time-consuming than the particle counter, but it is
more reliable. A quick real time data reading that reads well within the limit(s)
may be deemed acceptable, or a quick reading in excess of the limit could provide rapid information upon which to act to correct the cause of the elevated
levels, even prior to completion of the 24-hour monitoring time. Ideally, both
methods would provide the best of all worlds. That is in a perfect world!
Whereas LEED does not clarify sampling methods, the ASHRAE Standard
defines sampling and analytical procedures for the organic compounds—
formaldehyde, volatile organic compounds (VOC), and 4-PCH. The ASHRAEdefined testing procedures include one of or a combination of the following:
(1) EPA TO-1 (similar to TO-17, collection with Tenax®, thermal desorption,
analysis by GC-MS), (2) EPA TO-11 (aldehydes and ketones; similar to NIOSH
2016), (3) EPA TO-17, and (4) ASTM Standard Method D5197 (aldehydes; similar to NIOSH 2016).
EPA TO-17 is the most all inclusive approach for identification and analysis of most volatile organic compounds including 4-PCH, acrylonitrile,
2-ethylhexanoic acid, caprolactam, and phenol. The procedure, as detailed in
Chapter 8, “Volatile Organic Compounds,” is summarized as follows:
• Equipment: air-sampling pump
• Capture media: thermal desorption tube (e.g., Carbopak™), which
generally requires laboratory cleaning, conditioning
• Flow rate (TO-17): 10 to 50 milliliters/minute
• Flow rate (laboratory experience/preference): 50 to 100 milliliters/
minute
• Air volume limits: 1 to 6 liters (variable higher limits based on multibed sorbent and required reporting limits may be as high as 10
liters)
• Sample duration: minimum of 4 hours
• Desorption: thermal desorption
• Field blanks: minimum of one for up to ten samples in any given
sampling period
• Analysis: TD-GC-MS
• Limit of detection: 25 ng/sample (varies by laboratory)
• Special handling and shipping instructions: laboratory dependent
(some require ice pack for shipping)
Total VOCs, as required by LEED, is considerably less involved. LEED air
sampling may be done by any of the methods as presented in the Chapter 8.
Charcoal solid sorbent (active and passive) sample collection and analysis by
GC-FID is the easiest, most commonly used method, yet charcoal is limited in
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Indoor Air Quality: The Latest Sampling of Analytical Methods
its ability to collect polar VOCs and less volatile VOCs. Only TO-1 and TO-17 are
all inclusive, and 4-PCH and other carpet emission product are collected only
by TO-1 and TO-17.
LEED—Total VOCs 500 μg/m3
ASHRAE Standard—Component VOCs 2.5-7,000 μg/m3
LEED—4-PCH 5 μg/m3
ASHRAE Standard—4-PCH 2.5 μg/m3
As in all things big and small, there is an exception to every rule.
Formaldehyde requires separate sampling and analysis from that of VOC identification. Yes, it is a volatile organic compound, but formaldehyde is not readily
analyzed by gas chromatography. The rationale for this is that the reference
standard is generally formalin (formaldehyde in water), and water does not do
well in a gas chromatograph. As such, formalin reference standards tend to
fluctuate and are not reliable in a GC/MS. Furthermore, multibed solid sorbents
(EPA TO-17) tend not to capture the highly volatile organics such as formaldehyde. EPA TO-1, NIOSH 2016, and ASTM Standard Method D5197 are ideal for
analyzing aldehydes. The NIOSH 2016 procedure is summarized as follows:
•
•
•
•
•
•
•
•
•
Sampling equipment: air sampling pump
Collection medium: DNPH treated silica gel sorbent
Flow rate(s): 0.1 to 1.5 liters/minute
Sample duration: minimum of 4 hours
Field blanks: minimum of one for up to ten samples in any given
sampling period
Maximum air volume: 100 liters
Sample duration for indoor air quality: 8 hours
Detection limit: 50 ppt (1.2 liters/minute for 8 hours)
Analytical method: HPLC-UV detector
LEED—Formaldehyde 50 ppb
ASHRAE Standard—Component VOCs 33 μg/m3 (~26 ppb)
Carbon monoxide and ozone may be monitored by gas specific direct
reading instrumentation or by monitoring equipment designed to operate
in combination with other gases. A four-gas confined space entry monitor
always has a carbon dioxide sensor. An ozone meter is generally a single unit
and should be able to read levels as low as 0.075 ppm (e.g., Environmental
Ozone Meter Model Z-1200 reads to 0.02 ppm).
Green Buildings
331
LEED—Carbon monoxide 9 ppm
ASHRAE Standard—Carbon monoxide 9 ppm (or 2 ppm above
outdoors)
Ozone air sampling may be performed. The Occupational Safety and
Health Administration (OSHA) ID-214 Method for ozone air sampling is
as follows:
• Sampling equipment: air sampling pump
• Collection medium: 2-impregnated glass fiber filters coated with
solution containing NaNO2, K2CO3, and glycerol in water
• Flow rate: 0.25 to 0.5 liters/minute
• Field blanks: minimum of one for up to ten samples in any given
sampling period
• Maximum air volume: 90 liters
• Sample time: 3 to 8 hours
• Detection limit: 0.03 ppm (90-liter air sample)
• Analytical method: IC
ASHRAE Standard (only)—Ozone 0.075 ppm (8-hour sample)
There are various direct reading, real-time indoor air quality instruments
available that are capable of measuring and data logging many of the LEED
parameters. For instance, the Wolf Pack with PM-205 can read PM10, carbon
dioxide, and total VOCs. See Figure 19.4. It does not monitor formaldehyde levels,
and 4-PCH must be collected by air sampling and analyzed by a laboratory.
Interpretation of Results
Interpretation of results is simple! Either the building indoor air quality
passes or it fails. Pass/fail is based on the maximum concentration limits as
set forth by LEED (see Table 19.1) and the ASHRAE Standard (see Table 19.2).
While the LEED remains the benchmark for residences, the ASHRAE
Standard for high-performance buildings is considerably more restrictive.
In accordance with the ASHRAE Standard, each sampling point where the
maximum concentration limits have been exceeded, an additional flush-out
is mandated, and a retest for those specific parameter(s) that were exceeded
shall be done. Repeat this procedure until parameters have passed the litmus
test. All repeat samples should be taken from the same locations as the first.
332
Indoor Air Quality: The Latest Sampling of Analytical Methods
FIGURE 19.4
WolfPack with PM-205 particulate concentration meter (Courtesy of Graywolf Sensing
Solutions, Shelton, Connecticut).
TABLE 19.1
LEED’s Maximum Concentration of Air Pollutants
Contaminant
Particulates (PM10)
Carbon monoxide
Total VOC
Formaldehyde
4-PCHa
a
Maximum Concentration
µg/m3 (unless otherwise indicated)
50
9 ppm or no greater than
2 ppm above outdoor levels
500
50 ppb
6.5
This test is only required if carpets and fabrics with styrene butadiene rubber
(SBR) latex backing material are installed as part of the base building systems.
333
Green Buildings
TABLE 19.2
ANSI/ASHRAE Standard 189.1 Maximum Concentration of Air Pollutants
Contaminant
Particulates (PM2.5)
Particulates (PM10)
Carbon Monoxide
Ozone
Maximum Concentration µg/m3
(Unless Otherwise Indicated)
35 (24 hours)
35 (24 hours)
9 ppm or no greater than 2 ppm
above outdoor levels
0.075 ppm (8 hours)
Organic Compounds
Acetaldehyde
Acrylonitrile
Benzene
1,3-Butadiene
t-Butyl methyl ether (Methyl-t-butyl ether)
Carbon disulfide
Caprolactama
Carbon tetrachloride
Chlorobenzene
Chloroform
1,4-Dchlorobenzene
Dichloromethane (methylene chloride)
1,4-Dioxane
Ethylbenzene
Ethylene glycol
Formaldehyde
2-Ethylhexanoic acida
n-Hexane
Naphthalene
Nonanala
Octanala
4-Phenylcyclohexene (4-PCH)a
Styrene
Tetrachloroethene (Tetrachloroethlyene,
Perchloroethylene)
Toluene
1,1,1-Trichloroethane (Methyl chloroform
Trichloroethene (Trichlorethylene)
Xylene isomers
Total volatile organic compounds
a
b
140
5
60
20
8,000
800
100
40
1,000
300
800
400
3,000
2,000
400
33 (~26 ppb)
25
7,000
9
13
7.2
2.5
900
35
300
1,000
600
700
–b
This test is only required if carpets and fabrics with styrene butadiene rubber building
systems (SBR) latex backing material are installed as part of the base.
TVOC reporting shall be in accordance with CA/DHS/EHLB/R-174, Standard
Practice for the Testing of Volatile Emissions from Various Sources Using Small-Scale
Environmental Chambers, and shall be in conjunction with the individual VOCs listed
above.
334
Indoor Air Quality: The Latest Sampling of Analytical Methods
Summary
Going “green” by LEED is based on points, a rating system for “all structures,”
and indoor air quality testing is neither required nor is it the main focus.
Although it has continued make headway in the public sector, the LEED has
seen limited success in the private sector. As there is only an award of one
point for air quality testing, there is very little incentive for building owners
to seek the services of an environmental professional. Consequently, without
a building flush-out and confirmatory air monitoring, occupants of LEEDrated buildings may and have registered building-related health complaints.
Most residential HVAC systems do not have the ability to exchange outdoor
fresh air for a postconstruction flush-out. Many homes do not have operable
windows that can be opened to allow for air exchange with the outdoors. So
homeowners rarely have the ability to flush-out their home either mechanically or through dilution ventilation (e.g., opening all doors and windows),
and if it were possible, there is no means to filter the outdoor dust and debris.
Subsequently, there have been reports of occupant dissatisfaction with the
high cost of a LEED building and unexpected building-related health complaints. Litigation rears its ugly head, and the environmental professional
ends up in an after-the-fact web of lawsuits. Could this not have been prevented with the optional postconstruction air quality testing?
On the other hand, the ASHRAE Standard is a recommended standard, and it
is inclusive of and focused on indoor air quality. The standard “mandates indoor
air quality testing” after a high-performance building has been flushed. As ideal
as it is at addressing indoor air quality in green buildings, the ASHRAE Standard
excludes most residences and multifamily structures up to three stories high. This
is not to say homeowners cannot apply the standard wherein they so choose!
The exposure limits and parameters of the ASHRAE Standard far exceed
that of the LEED maximum concentrations. For example, PCH limits are 2.5
and 6.5, respectively. There are considerably less restrictive limits for the
LEED in all cases.
Furthermore, the ASHRAE Standard parameters include sampling for
PM 2.5 particles, identification of specified organics (instead of total organics), and ozone. “Green” has just taken on an all new meaning—healthy!
References
1. U.S. Green Building Council. USGBC and Sierra Club Volunteers Lead Green
Building Tours Across the U.S. (press release). March 16, 2010.
2. Beth Anderson. LEED Certification Program Leads to Potential Profits. Nuline
Investor (Dec. 3, 2007). http://www.nuwireinvestor.com/articles/leed-programleads-to-potential-profits-51367.aspx
3. LEED for Homes Checklist. U.S. Green Building Council (2010).
Glossary
abscess: A cavity containing pus and surrounded by inflamed tissue.
acid fast: A method of bacterial identification. Acid fast bacteria retain a
fuschin stain where other bacteria are rapidly decolorized when
treated with a strong mineral acid.
adsorption: Process of collecting a liquid or gas onto the surface of a solid or
liquid sorbent.
aerobic: Requiring the presence of oxygen for growth. Some aerobic microbes
may form capsules, or spores, when left in an oxygen-deficient
environment.
aflatoxin: Mycotoxin created by the molds Aspergillus flavis and parasiticus, a
known cancer-causing substance.
algae: Plantlike organisms that practice photosynthesis (requiring light) and,
for the most part, live in aquatic environments. They are occasionally implicated in outdoor allergies.
allergic pneumonia: An inflammation of the lungs resulting directly from
an allergy, usually to some type of organic dust.
alveolitis: An allergic pulmonary reaction characterized by acute episodes
of difficulty breathing, cough, sweating, fever, weakness, and pain
in the joints and muscles, lasting from 12 to 18 hours.
amoeba: A protozoan that has an undefined, changeable form and moves by
pseudopodia (or branching fingers of cellular material).
amplification: In reference to microbes, this means an increase in the numbers (generally due to growth and creation of elevated numbers
indoors).
anaerobic: Not requiring the presence of oxygen for growth (e.g., Clostridium
botulism, which causes canned food poisoning).
angioedema: This is a condition similar to urticaria (or hives), but involves
the subcutaneous tissue. It ordinarily does not itch and is a more
generalized swelling.
anisotropic: Substances having different refractive indices that depend on
the vibration direction of light.
ascospore: A haploid sexual spore created by the fungal class Ascomycetes
(e.g., yeasts).
asthma: A disease that is characterized by recurrent episodes of difficult
breathing and by wheezing, with periods of nearly complete freedom from symptoms.
atopic: Of or pertaining to a hereditary tendency to develop immediate
allergic reactions, such as allergic rhinitis, allergic asthma, and some
forms of eczema.
335
336
Glossary
autoimmune disease(s): A person’s immune system reacts against its own
tissues and organs.
bagassosis: A form of allergic lung disorder caused by exposure to moldy
sugar cane fiber.
bake-out: A process whereby the temperature of a building is elevated to
force chemical off-gassing of building materials and furnishings.
This is generally performed without building occupants, and the
air is flushed with outside air after a predesignated time period.
basidiospores: Sexual spores created by the fungal class Basidiomycetes
(e.g., common mushroom).
birefringence: The numerical difference in refractive indices for a substance.
booklice (or book louse): Small, six-legged insects belonging to the order
Psocoptera that are implicated in paper dust allergies.
bronchitis: An inflammation of the mucous membranes of the bronchial
tubes, characterized by difficulty breathing.
carcinogenic: A substance capable of causing cancer.
challenge test: A medical procedure, also known as provocative testing, used to
identify substances to which a person is sensitive by deliberately exposing the person to diluted amounts of the substance. A positive bronchial
challenge is one in which pulmonary function decreases.
chronic REL: Noncancer chronic reference exposure level developed by
California EPA. These are inhalation concentrations to which the
general population, including sensitive individuals, may be exposed
for long periods of time (e.g., 24 hours a day for 10 years) without the
likelihood of serious adverse systemic effects.
commensal: Organisms that live in close association whereby one may benefit from the association without harming the other.
competition: Negative relationships between two populations in which both
are adversely affected with respect to their survival and growth.
conidia: Asexually produced spores which develop at the end of a conidiophore (e.g., Penicillium).
conidiophore: The structure from which conidia develop.
conjunctiva: The mucous membrane lining of the inner surfaces of the eye.
conjunctivitis: Inflammation of the conjunctiva. This results in eye redness,
a thick discharge, sticky eyelids upon waking in the morning, and
inflammation of the eyelids.
croup: An infection of the upper and lower respiratory tract that occurs primarily in infants and young children up to 3 years of age. It is characterized by hoarseness, fever, a distinctive harsh, brassy cough, a
high-pitched sound when breathing, and varying degrees of respiratory distress.
culturable: Viable (or live) microorganisms that can be grown.
desorption: Process of running adsorbed liquids/gases from sorbent material.
dispersion staining: Staining based upon the differences and similarities of
the refractive indices between a solid and liquid.
Glossary
337
dispersion: The separation of light into its color components by refractive or
diffracted light.
dust mites: Almost invisible to the naked eye, these eight-legged arachnids
are typically implicated in house dust allergies that are thought to
be associated with whole or portions of their bodies and feces. They
are one of, if not the most common indoor allergens and are known
to cause asthma attacks, not dermatitis.
dyspnea: Difficulty breathing.
eczema: A superficial dermatitis that, in the early stages, is associated with
itching, redness, fluid accumulation, and weeping wounds. It later
becomes crusted, scaly, thickened, with skin eruptions.
emission factor: A single point quantitative measurement of gaseous or particle emissions from a material, as determined by chamber testing.
emission rate: The actual rate of release of vapors/gases from a product over
time.
emphysema: A chronic disease of the lungs in which the alveoli are permanently damaged or destroyed. It is typically characterized by difficult
breathing and is associated with heavy, prolonged cigarette smoking.
endocarditis: Lesions of the lining of the heart chambers and heart valves.
endotoxic shock: A body reaction caused by an endotoxin, generally characterized by marked loss of blood pressure and depression of the vital
processes.
endotoxin: A toxin produced within bacteria and released upon destruction
of the cell in which it was released.
environmental chamber: A nonreactive testing enclosure of known volume
with controlled air change rates, temperature, and humidity.
epitope: The portion of an antigen molecule involved in binding to the
antibody.
farmer’s lung: A form of allergic lung disorder caused by exposure to moldy
hay.
flush-out: Replace indoor serviced air with the outdoor air. The flush-out
rate is the volume of outdoor air required to replace the same volume of indoor air for each area serviced.
fomites: Inanimate objects (e.g., mineral dust particles).
forensic: Relating to or dealing with the application of scientific knowledge
to legal issues.
fungi: Plants that, unlike green plants, have no chlorophyll and must depend
on plant or animal material for nourishment.
gastroenteritis: An inflammation of the stomach and intestines. It may at
times result from an allergic reaction.
Gram negative: A staining process that is used in diagnostic bacteriology
whereby the bacterial wall is stained pink.
Gram positive: A staining process that is used in diagnostic bacteriology
whereby the bacterial wall is stained purple, almost exclusively a
property of producers of potent exotoxins.
338
Glossary
granuloma: A granulated nodule of inflamed tissue.
hapten: A low molecular weight chemical that is too small to be antigenic by
itself but can stimulate the immune system when combined with a
larger molecule (e.g., protein).
hay fever: Common name for “nasal allergy.” Its symptoms include attacks of
sneezing, runny, stuffy nose, and itchy, watery eyes, and they occur
within a few minutes to a few hours after exposure to inhaled allergens, usually pollen, spores or molds, house dust, or animal dander.
The term hay fever is misleading, since these reactions are not usually
produced by hay and are not accompanied by fever.
hemorrhagic shock: Physical collapse and prostration associated with sudden and rapid loss of large amounts of blood.
heterologous (cross-reactive) antigen: A different antigen from that which
was used to immunize or challenge the immune system, yet it is
similar enough to be recognized as the initial foreign substance.
Typically, these antigens are polysaccharides, possibly due to their
limited chemical complexity and often structurally similar in nature
to one another. For example, human blood Group B sometimes reacts
with antibodies to certain strains of Escherichia coli that are a common bacterial resident in the human colon.
high-performance building: In accordance with American National Standards
Institute (ANSI)/American Society of Heating, Refrigerating and Air
Conditioning Engineers (ASHRAE) Standard 189.1, a high-performance
building is “a building designed, constructed, and capable of being
operated in a manner that increases environmental performance and
economic value over time, seeks to establish an indoor environment
that supports the health of occupants, and productivity of occupants
through integration of environmentally preferable building materials and water efficient and energy-efficient system” (not applicable to
single-family homes, multifamily structures of three stories or fewer
above grade, manufactured homes, manufactured houses, and buildings that do not have electricity, fossil fuel, or water).
hives (urticaria): A common skin condition that is probably familiar to everyone. It is a skin rash characterized by areas of localized swelling, usually
very itchy and red, and occurring in various parts of the body. It usually
lasts only a few hours and involves only the superficial areas of the skin.
Urticaria has either an immunologic or a nonimmunologic cause.
homologous antigen: A foreign substance used in the production of
antiserum.
house dust: Heterogeneous, firm gray powdery material that accumulates
indoors. This category includes mold, pollen, animal dander, food
particles, kapok, cotton lint, insects, and bacteria.
humidifier fever: Aerosolized microbial infection that causes flu-like symptoms such as fever, headache, chills, muscle aches, and fatigue. It
usually subsides within 24 hours of onset.
Glossary
339
hybridized: Bound to a template of DNA sequencing.
hypersensitivity pneumonitis: An inflammation of the alveoli within the
lungs caused by allergenic dusts.
hypersensitivity: A condition in which the immune system reacts to antigens that cause tissue damage and disease.
hyphae: A microscopic filament of cells that represents the basic unit of a
fungus. They usually do not exist with yeasts.
immune: A condition in which an organism is protected against, or free
from, the effects of allergy or infection, either by already having had
the disease or by inoculation.
immunoglobulins: One of a family of proteins to which antibodies belong.
in vitro: In an artificial environment.
in vivo: In a live organism.
incidence: Number of new diseases occurring in a given population at a
specified time period.
isotropic: Substances showing a single refractive index at a given temperature
and wavelength, no matter what the direction of light may be.
itch mites: Almost invisible to the naked eye, these eight-legged arachnids
cause itchy red marks and are sometimes implicated in house dust
allergies but generally associated with straw, hay, grasses, leaves,
and seeds.
ligase: Protein that acts as a glue to hold bits of DNA molecules together.
lipids: Fats and fattylike materials that are generally insoluble in water.
lymphocyte: A white blood cell important in immunity. Of the two major
types (both types have several subclasses), T-lymphocytes are processed in the thymus and are involved in cell-mediated immunity,
and B-lymphocytes are derived from the bone marrow and are precursors of plasma cells, which produce antibody.
macrophage: A scavenger white blood cell that plays a role in destroying invading bacteria and other foreign material. It also plays a major role in the
immune response by processing or handling antigens and as an effector cell (e.g., muscle or gland) in delayed hypersensitivity.
meningitis: An infection or inflammation of the membranes covering the
brain and spinal cord. Onset symptoms are characterized by severe
headache, stiffness of the neck, irritability, malaise, and restlessness,
followed by nausea, vomiting, delirium, and disorientation. This
progresses to increased temperature, pulse rate, and respiration.
Nerve damage may culminate in deafness, blindness, paralysis, and
mental retardation.
micron (or micrometer): One millionth of a meter (10 –6).
mold: Microscopic plants, belonging to the fungi kingdom, which do not
have stems, roots, or leaves and are composed of a vegetative threadlike element (hyphae) and reproductive spores.
340
Glossary
monoclonal antibody: Antibody produced by a single clone of cells that
binds to only one epitope.
mushroom: Microscopic plants, belonging to the fungi kingdom, that are
filamentous in nature with large fruiting bodies (referred to as the
mushroom cap) that discharge reproductive spores.
mutagenic: Capable of causing a genetic change.
mycelium: A visible mass of tangled filaments of fungal cells, the rooting
structure and extension of the more aerial hyphae.
mycotoxins: Toxins produced by molds.
nanometer: One one thousandth of a micron, or one billionth of a meter
(e.g., 10 –9).
nasal congestion: Blockage of the nasal passages.
necrosis: Localized tissue death.
neutralism: A lack of interaction between two microbial populations.
nonpolar compounds: Compounds that have atoms that do not have a denser
electron cloud about one atom, or group of atoms, than around its
adjoining atom, or group of atoms (e.g., hexane).
nonviable: Not living, dead, destroyed organisms; not capable of causing
disease.
nosocomial: Hospital-acquired infections.
paper mites: Fictitious term with possible reference to storage mites or
booklice.
parasitism: One population benefits and normally derives its nutritional
requirements from the population that is harmed.
patch test: Used to identify substances responsible for contact allergy. The
test consists of applying a small amount of a suspected substance to
the skin. The area is covered with tape and left for forty eight hours.
If is a small area where the substance was applied swells and turns
red, the test result is said to be positive.
Petri plate (or dish): A glass or plastic dish that has a lid, and it is used to
isolate and grow microbes.
plasmids: Small loops of DNA in bacteria (contain genes for antibiotic
resistance).
pleurisy: Inflammation of the pleura (or membranous sacs surrounding the
lungs).
polar compounds: Compounds that have atoms that have a denser electron
cloud about one atom, or group of atoms, than around its adjoining
atom, or group of atoms (e.g., butanol).
pollen: Male fertilizing elements of a plant, which are microscopic in size.
Pollen grains are spheroid, ovoid, or ellipsoid in shape and may
have a smooth, reticulated (e.g., network), speculated (e.g., spikes or
points), or sculptured surface.
predation: One organism, the predator, engulfs and digests another organism, the prey.
Glossary
341
predicted air concentrations: A calculated prediction of air concentrations of
a given substance or substances, based on component emission rates.
prevalence: Normal frequency of a disease in a given population.
prick method: An allergy test whereby the skin is pricked with a needle at
the point where a drop of allergen has been placed, introducing the
allergen to the body’s immune system.
product loading: Ratio of the amount of material to be placed in an emissions test chamber to the volume of the chamber. The number may be
based on area (i.e., m2/m3), mass (i.e., g/m3), or unit (1 unit/m3).
pyrexia: A condition resulting in fever.
pyrocanic: Sensation of heat.
ragweed: A plant, belonging to the family Compositae, that is the major
cause of hay fever in the United States. The ragweed family is large,
with approximately 15,000 species.
restriction enzymes: Proteins that cut apart DNA molecules.
retractive index: The ratio of the velocity of light in a vacuum to the velocity of light in a given medium. A higher atomic number generally
results in a higher refractive index.
rheumatic fever: An inflammatory disease that usually occurs in young
school-aged children and may affect the brain, heart, joints, skin,
or subcutaneous tissues. Early on, it is characterized by fever, joint
pains, nose bleeds, abdominal pain, and vomiting, progressing to
chest pain and, in advanced cases, heart failure.
rheumatoid arthritis: A chronic, destructive, often deforming, collagen disease
that results in inflammation of the bursa, joints, ligaments, or muscles.
It is characterized by pain, limited movement, and structural degeneration of single or multiple parts of the musculoskelatal system.
rhinitis: A disease of the nasal passages that is characterized by attacks
of sneezing, increased nasal secretion, and stuffy nose (caused by
swelling of the nasal mucosa).
rust: A fungal disease of agricultural crops so named because of the orangered color it imparts to infected plants. Belongs to the same fungal
class as the common mushroom.
saponification: The hydrolysis of an ester by an alkali, producing a free alcohol and an acid salt.
saprophytic: Lives on and derives its nourishment from dead or decaying
organic matter.
scratch test: A small drop of an allergen is applied over an area of the skin
where a superficial scratch has been made. This allows the allergen
to penetrate the top layer of skin.
semivolatile: Compounds with a boiling range of 240°C to 400°C.
sensitize: To administer, or expose, to an antigen provoking an immune
response so that, upon later exposure to that antigen, a more vigorous secondary response will occur. An individual can be immune
(e.g., protected against the effects of an infectious agent or antigen)
342
Glossary
and sensitized to the antigen (e.g., demonstrate a positive tuberculin
reaction) at the same time.
septicemia: Systemic infection where pathogens are spread through the
bloodstream, infecting various parts of the body, characterized by
fever, chills, prostration, pain, headache, nausea, and diarrhea.
skin test: A method of testing for allergic antibodies. A test consists of introducing small amounts of the suspected substance, or allergen, into
the skin and noting the development of a positive reaction (which
consists of a wheal, swelling, or flare in the surrounding area of redness). The results are read 15 to 20 minutes after application of the
allergen.
slime mold: Organisms, belonging to the fungi kingdom, that are protozoanlike for part of their life cycle and reproduce by forming stalks that
produce spores (or multiple spore-containing sporangia).
smut: A fungal disease of agricultural crops so named because of the sooty
black appearance it imparts to infected plants. Belongs to the same
fungal class as the common mushroom.
sorbent: A solid or liquid material that collects liquid or gaseous
substances.
sporangiospores: Asexually produced spores that develop within a
sporangium.
sporangium: A structure, or sac, within which spores develop.
spores: Reproductive cells of certain plants and organisms. Inhaled fungal
spores are frequently the cause of allergic symptoms such as rhinitis
and asthma.
storage mites: Four-legged arachnids that are sometimes implicated in
outdoor environmental allergies associated with agricultural
environments.
symbiotic: Obligatory relationship between two populations that benefits
both populations.
synergistic: Mutually cohabitate with one another.
teleospores: Asexual spores produced by rusts.
thymine: A DNA base that only pairs to the base adenine.
tobacco sensitivity: Many people suffering from rhinitis and asthma experience heightened symptoms when exposed to tobacco smoke.
transparency: Ability to transmit light.
ulceration: Formation of a circular, craterlike lesion of the skin or mucous
membranes.
unculturable: Viable and nonviable microorganisms that cannot be grown.
urediospores: Asexual spores produced by smuts.
urticaria (hives): This is a skin rash characterized by areas of localized
swelling, usually very itchy and red, and occurring in various parts
of the body. It usually lasts only a few hours and involves only the
superficial areas of the skin.
Glossary
343
viable: Living organism; capable of causing disease. In reference to mold,
viable means the spores that will grow, given the proper growth
media.
viron: An intact virus particle that has the ability to infect.
virus: A submicroscopic organism that consists of genetic material and a
coating and requires living organisms in order to reproduce.
viscera: The internal organs enclosed within a body cavity, primarily the
abdominal organs.
Volatile organic compound(s): Organic compounds that vaporize at relatively low temperature.
volatile: Compounds with a boiling range of 0°C to 290°C.
xerophilic: Organisms that grow where there is low water availability.
yeasts: Species of fungi that grow as single cells.
zeophylic: Dry-loving organism.
Appendix A: Abbreviations/Acronyms
AAAAI: American Academy of Allergy, Asthma, and Immunology
ACGIH: American Conference of Governmental Industrial Hygienists
AGI: All glass pinger
AHU: Air Handling Unit
AIDS: Auto Immune Deficiency Syndrome
ANSI: American National Standards Institute
ASHRAE: American Society of Heating, Refrigerating and Air‑conditioning
Engineers
BA: Blood Agar
BIFM: British Institute of Facilities Management
CDC: Center for Disease Control
CFM: Cubic Feet per Minute
CFR: Code of Federal Regulations
CFU: Colony Forming Units
CIH: Certified Industrial Hygienist
CO: Carbon monoxide
CO2: Carbon dioxide
CREL: Chronic Reference Exposure Limit
CRI: Carpet and Rug Institute
DNPH: Dinitrophenylhydrazine
DOT: Department of Transportation
EDX/EDXRA: Energy Dispersive X‑Ray Analyzer
EMA: Electron Microprobe Analyzer
EPA: Environmental Protection Agency
EU: Endotoxin Units
FDA: Food and Drug Administration
FID: Flame Ionization Detector
FTIR: Fourier Transform Infrared Spectrometry
GC: Gas Chromatography
GC/ECD: Gas Chromatography/Electron Capture Detector
GC/FID: Gas Chromatography/Flame Ionization Detector
GC/MS: Gas Chromatography/Mass Spectrometry
GC/NPD: Gas Chromatography/Nitrogen Phosphorous Detector
GC/NSD: Gas Chromatography/Nitrogen Selective Detector
GEN: Global Ecolabelling Network
HEPA: High Efficiency Particulate Airfilter
HPLC: High Pressure Liquid Chromatography
HPLC/UV: High Pressure Liquid Chromatography/UV Detector
HRP‑SA: Horseradish Peroxidase‑Streptavidin
HUD: Housing and Urban Development
345
346
Appendix A
HVAC: Heating, Ventilation, and Air Conditioning
IAQ: Indoor Air Quality
IC: Ion Chromatography
IMA: Ion Microprobe Analyzer
IP: Indoor Pollutant Methods (EPA)
KLARE: Kinetic‑Turbidimetric Limulus Assay with Resistant-parallel‑line
Estimates (Test)
LEED: Leadership in Energy and Environmental Design
LEL: Lower Explosion Limit
MPI: Mass Psychogenic Illness
MSDS: Material Safety Data Sheet
MVOC: Microbial/Mold Volatile Organic Compounds
NA: Not Applicable
NAB: National Allergy Bureau (Program under the American Academy of
Allergy, Asthma, and Immunology)
NIOSH: National Institute for Occupational Safety and Health
NPD: Nitrogen Phosphorous Detector
OSHA: Occupational Safety and Health Act
OVA: Organic Vapor Analyzer
PCH: 4-Phenylcyclohexene
PID: Photoionization Detector
PM2.5: Particulate matter with an aerodynamic diameter less than or equal
to 2.5 microns (respirable)
PM10: Particulate matter with an aerodynamic diameter less than or equal
to 10 microns (thoracic)
ppb: parts per billion
ppm: parts per million
ppt: parts per trillion
RBA: Rose Bengal Agar
RH: Relative Humidity
RT: Room Temperature
SAED: Selected Area Electron Diffraction
SEM: Scanning Electron Microscopy
TCLP: Toxicity Characteristic Leaching Procedure
TEM: Transmission Electron Microscopy
TLV‑TWA: Threshold Limit Value‑Time‑Weighted Average
TO: Toxic Organic Methods (EPA)
TSA: Tryptic Soy Agar
TVOC: Total Volatile Organic Compounds
UEL: Upper Explosion Limit
VAS: Visual Absorption Spectrometry
VAV: Variable Air Volume
VOC: Volatile Organic Compound
WHO: World Health Organization
Appendix B: Units of Measurement
Volume
1 liter (L) = 1.06 quarts
1 milliliter (mL) = 10 –3 liter
1 microliter (µL) = 10 –6 liter
Length
1 meter (m) = 3.281 feet = 39.37 inches
1 centimeter (cm) = 10 –2 meter = 0.039 inch
1 millimeter (mm) = 10 –3 meter
1 micrometer (µm) = 1 micron (p) = 10 –6 meter
Weight
1 gram(s) (g) = 0.035 ounce
1 milligram (mg) = 10 –3 gram
1 microgram (µg) = 10 –6 gram
1 nanogram = 10 –9 gram
1 picogram = 10 –12 gram
Temperature
1° Fahrenheit (F) = [(1.8) (X°C)] + 32
1° Centigrade (C) = [X°F – 32]/1.8
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Appendix B
Sample Units
ppm = parts of contaminant per million parts of sample material (e.g., air)
ppb = parts of contaminant per billion parts of sample material
ppt = parts of contaminant per trillion parts of sample material
mg/m3 = milligrams of contaminant per cubic meter of sample material
pg/m3 = micrograms of contaminant per cubic meter of sample material
grains/m3 = grains of pollen per cubic meter of air sample
CFU/m3 = colony forming units per cubic meter of air
mg/m2‑hour = milligrams of contaminant per square meter of material in
one hour
mg/X‑hour = milligrams of contaminant per item, or composite unit, (X) in
one hour of emissions testing
mg/hour‑m3 = milligrams of contaminant emitted in one hour within a three
cubic meter space
μg/X‑hour = micrograms of contaminant per item, or composite unit, (X) in
one hour of emissions testing
Flow Rates
cubic centimeter per minute (cc/min)
liter per minute (Lpm)
milliliters per minute (mL/min)
Appendix C: Allergy Symptoms
Common Allergy Symptoms
Many of the allergy symptoms are commonly known and understood. Yet
some are not acknowledged by the general public. Improperly interpreted
allergy symptoms may result in a search for other causes of a given symptom
other than allergens. The investigator should be familiar with the symptoms
as presented herein.
Allergic Asthma
Asthma generally results when cold air, pungent odors, viral infections, aspirin and related drugs, inert dusts, or allergens cause hyperactivity of the airways with narrowing of the air passages. This is translated into a tightening
sensation of the chest and breathing difficulties associated with coughing and
wheezing. Movement of the chest‑wall muscles may be felt as a heavy weight,
a constriction of the lungs. If complications involve the pneumothorax, rib
fracture, or pneumonia, chest tightness becomes pronounced and painful.
Breathing could become excruciating and resemble symptoms of pleurisy.
Strenuous exercise may also heighten the severity as exposure levels
increase. In severe episodes, the sufferer may also experience wheezing and
mental dullness due to reduced oxygen inspired/delivered to the brain.
If a person has been relatively free of asthma until exposure to animals,
cut grass, or a virus, and if the exposure is brief, the attack should subside
with proper treatment. It may even subside spontaneously.
Allergic Dermatitis
Although acute symptoms of allergic dermatitis are not singularly diagnostic,
they characteristically involve itching, redness, swelling, and a scaly rash.
Itching can be intense and may lead to what is known as weeping lesions,
caused by the serum oozing from the underlying small blood vessels. Typical
areas of the body for this to happen are the cheeks, the creases behind the
ears, and at the bends of the arms and legs.
Commonly called eczema or atopic dermatitis, the rash can spread enough
to become disabling. During the healing stage, the affected skin thickens,
becomes dry, and cracks. Some bleeding may also occur during this stage.
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Appendix C
A local infection that takes the form of skin boils is serious and should be
considered a threat to the comfort of the individual. As their immune system
has yet to develop completely, infants and young children may not demonstrate as severe a reaction as an adult. They may simply develop a red, flat,
scaly rash without the annoyance experienced by older individuals.
Allergic Rhinitis
Allergic rhinitis is characterized by nasal congestion and sneezing, which
are, in turn, associated with irritation of the throat, eyes, and ears.
Eye Pain
Allergic conjunctivitis can induce a painful, burning condition known as
pink eye. Bright light often adds to the discomfort, leading the individual to
appear to be afraid of light. Severe watering and squinting may occur.
Hay Fever
When symptoms are seasonal, allergic rhinitis is referred to as hay fever.
Such allergens include pollen and mold spores. Itching of the nasal passages
is a common symptom associated with pollen and mold spores. In an attempt
to relieve the discomfort, a sufferer frequently performs nose‑rubbing rituals
and facial contortions. Itching of the roof of the mouth and inner corner of
the eyes may further contribute to demonstrations of distress.
Inner Ear Pain and Hearing Loss
Allergic rhinitis is associated with extensive fluid leakage into the middle
ear. Fluid buildup causes an aching pain that can temporarily diminish
hearing. If untreated the condition can cause fever and increased pain, and
lead ultimately to rupture of the eardrum.
Nasal Congestion
Nasal congestion may result in breathing difficulties due to blockage of the
nasal passages. Congestion may also result in a watery, blood‑flecked discharge either from the nose or back of the throat. Some allergy sufferers
describe a tickle of the throat. Drainage and throat irritation provoke coughing and other indirectly related problems.
When nasal blockage occurs, allergy sufferers tend to breathe through their
mouths and frequently lose sleep. The problem thus culminates in fatigue
and irritability. Although these symptoms are associated with allergies, it is
important that the environmental professional be aware that they may be the
result of other problems that may require a physician.
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351
Not all nasal discharges are caused by allergies. Simple colds or virus
infections may simulate allergic disease. Allergic disease is not normally
accompanied by the presence of fever, general aching, and a yellow or green
nasal discharge. When exposed to unusually high levels of an allergen, an
allergy sufferer may develop a systemic reaction where general aching is
the primary symptom. Yellow or green nasal/throat discharges are generally associated with viral or bacterial infections, and an infection lasts
about two weeks. An allergic condition comes and goes with environmental changes.
Another cause of congestion that should not be confused with allergic
rhinitis is that which is caused by a tumor obstruction. Nasal blockage may
result from polyps—normal or malignant growths of sinus and nasal tissue filled with fluid, which may or may not be the result of allergy‑caused
postnasal drip. If the blockage persists unabated for several days, both loss
of smell and nasal/sinus infections may result.
Sinus Headache
Sinus obstruction results in area related headaches. The sinuses have outlets
or air spaces through the nasal passages. These air spaces are located near
the nose, under the cheeks, and above the eyes. When the spaces become
obstructed, buildup of air or fluid leads to increased pressure, resulting in
pain. This pain may range from a dull discomfort to a sharp, steady ache in
the areas involved (e.g., above the eyes). This is referred to as a sinus headache, or sinusitis.
Other Allergy-Related Diseases
Some rare forms of allergy‑related illness occur in less than 1 percent of the
United States population. Awareness concerning some of their symptoms
may be relevant to an overall investigation of environmental impact of airborne allergens. These are discussed herein.
Allergic Bronchopulmonary Aspergillosis
Allergic bronchopulmonary aspergillosis is, as the name implies, an allergic
disease that involves exposures to the fungus Aspergillus. Aspergillus fumiga­
tus is generally the species implicated. This disease involves invasion of the
mucous lining of the air passages within the lungs. Affected individuals may
experience a persistent cough associated with sputum, asthmalike symptoms, fever, and chest pain. Viable spores are the initiator and, once invasion
has occurred, the disease is progressive until treatment is administered.
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Appendix C
Contact Dermatitis
Contact dermatitis involves an itchy, red rash that is generally confined to
the site of exposure. Scratching may lead to blistering. Although the areas
impacted are commonly exposed skin surfaces, exposures may result from
transference of allergen from one place to another (e.g., scratching unexposed
skin surfaces with contaminated fingernails). The most common exposures
are to oils from poison ivy and poison sumac, which if burned may become
airborne or are spread by contact with weeping sores. Removal from and
avoidance of the allergen will, in most cases, provide relief within two weeks
if the affected areas are left alone.
Hives
Hives, or urticaria, are generally associated with food or drugs. On rare
occasions they may be associated with animal allergens, skin contact with
the mold Penicillium, and Hevea brasiliensis latex. Raised bumps may appear
anywhere on the body. These may range in size from that of a small pea
to large sections of the body and are often accompanied by red haloes and
itching. Each lesion may last only a few hours, but new ones can appear at
frequent intervals, and itching may become so intense that it is difficult to
perform simple tasks or sleep.
Hypersensitivity Pneumonitis
Hypersensitivity pneumonitis, or allergic alveolitis, generally involves an
occupationally related inflammation of the alveoli and bronchioles of the
lungs. Acute pneumonitis (short term, extremely high exposures) results in
breathlessness, chills, and fever. Fever may be as high as 104°F, and, within
four to six hours symptoms progress into muscle aches and moodiness. Chest
x-rays may show diffuse nodular shadows that are predominately found in
the lower portions of the lungs.
Subacute symptoms occur upon repeated exposures and appear as chronic
bronchitis. This phase is characterized by repeated exposures and by recurring cough, breathlessness, weight loss, and malaise.
Chronic exposures to low levels of antigenic material may be demonstrated by less obvious symptoms. The allergy sufferer may only experience breathlessness and weight loss, but the chest x-rays will reveal
progressive scarring. Pulmonary function tests will show declining functional lung volume. Diagnostic confirmation of the various stages of the
disease generally requires the aid of a physician. Common occurrence
of the disease is typically limited to bird handlers and to farmers in the
southeast. Disease is generally associated with a known source and is
region dependent.
Appendix D: Classification
Volatile Organic Compounds
Alcohols
Due to its association with cosmetics, the more commonly found alcohol
in indoor air quality is isopropanol. Alcohols are most frequently used as
solvents, perfumes, components of pharmaceuticals (e.g., cough medicine),
cleaning agents (e.g., packaged as hand wipes), and fuel additives. The aliphatic alcohols have a distinct “alcohol” odor, and the aromatic alcohols have
more of a medicinal or creosote odor.
Low-level exposures to aliphatic alcohols may result in irritation of the
eyes and upper respiratory tract, occasionally headache and dizziness. The
lowest 8-hour exposure for volatile alcohols is 1 ppm (American Conference
of Governmental Industrial Hygienists [ACGI] limit for propargyl alcohol).
Airborne exposures to alicyclic and aromatic alcohols may result in irritation
of the eyes and upper respiratory tract, anorexia, weight loss, weakness, and
muscle aches and pain.
Aldehydes
The aldehydes are commonly encountered in indoor air quality. They are
most frequently used as cleaning agents, biocides, and constituents of resins.
Odors have been described as sharp, pungent.
The aldehydes follow the First Member Rule in that formaldehyde is the
most toxic of the group. Although not as common as many people would
suspect, formaldehyde has been known to cause skin sensitization that may
demonstrate itself in a fashion like poison ivy, and formaldehyde is a suspect
human carcinogen. Airborne exposures to aldehydes may result in irritation
and a burning sensation of the eyes, upper respiratory tract, and skin.
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Appendix D
Aliphatic and Alicyclic Hydrocarbons
Many of the volatile organic compounds (VOCs) found in indoor air quality
are aliphatic (e.g., methane) and alicyclic (e.g., cyclohexane) hydrocarbons.
Methane, an aliphatic, is evolved during the animal and plant decay, and
it is encountered in the atmosphere typically at levels of 1.8 ppm. Many of
the aliphatics and alicyclics are components of gasoline, and they are used
for heating, welding, illumination gases, refrigeration, and solvents. The aliphatics and alicyclics do not have an odor.
With a low toxicity, the principal effect of aliphatic and alicyclic VOCs is
narcosis at very high exposure levels, in excess of what would normally be
found in indoor air quality. Symptoms may include lightheadedness, headache, and irritation of the eyes and nose.
Aromatic Hydrocarbons
Most of the more commonly encountered organics in indoor air quality are volatile aromatic hydrocarbons. Aromatics are most frequently used in solvents,
and they are a component of gasoline. They have a pleasant, “aromatic” odor.
The aromatic hydrocarbons follow what is referred to as the “First Member
Rule.” This rule states that the toxicity of the first member of a homologous
series is likely to differ qualitatively from the toxicity of the other members
of the same series. For instance, benzene, the first member in the aromatic
hydrocarbon series, is the more toxic of the aromatics, causes damage to the
blood cell-forming system, and is a suspect human carcinogen. The other
aromatics are neither as toxic, nor known to cause the same extreme health
effects as benzene.
The health effects associated with aromatic VOCs at low levels anticipated in nonindustrial environments are narcosis and moderate irritation.
Symptoms may include fatigue, weakness, dizziness, headache, and irritation of the eyes, nose, and throat.
Esters
Esters are occasionally encountered in indoor air environments. They are
most frequently used as solvents, and commonly found in highlighter pens.
Esters have sweet, variable odors (e.g., bananas or wintergreen) and are often
Appendix D
355
used for food. Airborne exposures to esters may result in irritation of the
eyes and upper respiratory tract and narcosis. Symptoms may include headache and throat irritation.
Ethers
The ethers are rarely encountered in indoor air environments. They are a
narcotic and frequently used for anesthesia and have been used in solvents,
making gun powder, refrigerant, and aerosol propellant. Odors have been
described as sweet and pleasant.
Low-level exposures to glycol ethers may result in irritation of the eyes and
upper respiratory tract. The lowest 8-hour exposure for volatile alcohols is
400 ppm (ACGIH limit for ethyl ether).
Glycol Ethers (i.e., Cellosolves)
The glycol ethers are occasionally encountered in indoor air environments.
They are most frequently used as solvents (referred to by the trade name of
Cellosolves) in dry cleaning, nail polishes, varnishes, and enamels. Odors
have been described as sweet and musty. Airborne exposures to glycol ethers
may result in irritation of the eyes and upper respiratory tract.
Halogenated Hydrocarbons
Other than the ubiquitous Freon, the volatile halogenated hydrocarbons
are less frequently encountered in indoor air environments. They are most
frequently used as solvents. Halogenated hydrocarbons have a faint sweet
odor.The halogenated hydrocarbons follow the First Member Rule in that
halogenated methanes (e.g., methyl bromide and chloroform), ethanes (e.g.,
vinyl bromide), and benzenes (e.g., benzyl chloride) are the more toxic of the
group. They are narcotic, can cause liver and kidney damage, depression of
the bone marrow activity, and are suspected human carcinogens. Airborne
exposures to all other halogenated hydrocarbons may result in headache,
dizziness, and nausea.
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Appendix D
Ketones
Ketones are occasionally encountered in indoor air environments. They
are most frequently used as solvents. They are also used in antifreeze
solutions and hydraulic fluids. The most commonly found ketones in
indoor air are acetone and methyl ethyl ketone. Ketones have a faint pleasant odor. Airborne exposures to ketones may result in irritation of the eyes
and upper respiratory tract and narcosis. Symptoms may include headache
and throat irritation as well.