(IAQ)
Introduction
 A chemical having at least one carbon and hydrogen atom in its molecular
structure is referred to as Organic Compound
 Organic compounds are divided mainly based on their vapor pressure at room
temperature into:
 Volatile Organic Compounds (VP > 1 mm of Hg)
 Semi-Volatile Organic Compounds(10E - 7 > VP < 1 mm of Hg)
 Non-Volatile Organic Compounds (VP < 10 E -7 mm of Hg)
Introduction(contd.…)
 EPA conducted comprehensive studies on Indoor Air Quality in U.S. under the
name of Total Exposure Assessment Methodology (TEAM)
 The study showed that the targeted 22 chemicals (Pollutants) had higher
concentrations indoors than outdoors
 Formaldehyde (used in resin) is suspected of being carcinogenic at present
indoor levels which may be a critical problem
The 22 Targeted VOCs by the U.S. EPA (1986)
Vinyl Chloride
Methylene Chloride Chloroform
Carbon
Tetrachloride
1,1,1Trichloroethane
Trichloroethylene
Tetrachloroethylene
Benzene
o-Xylene
m,p-Xylene
m,p-Dichlorobenzene
Ethylbenzene
Styrene
1,2-Dichloroethane
1,1,1,2Tetrachloroethane
1,1,2,2Tetrachloroethane
n-Butlyacetate
Hexachloroethane
Decane
Chlorobenzene
Ethylphenol
Acrolein
Pollutants associated with various activity levels
Cleaning windows
Ammonium hydroxide
Spots/textiles
Tetrachloroethylene, Trichloroethylene, Methanol, Benzene
etc.
Soaps/detergents
Polyether sulphates, Alcohol, Sulfonates, alkylsodium
isothionates
Oven
Sodium hydroxide, Potassium hydroxide
Drain/toilet bowl
Sodium hydroxide, Lye
Vacuuming of
carpets
Dust
General cleaning
Ammonium hydroxide, Lye, Chlorine, Sodium hypochloride
etc.
Pollutants associated with various activity levels
Painting/varnishing
Toulene, Xylene, Methyl chloride, Heavy metals, Pigments,
Methanol, Ethylene glycol, Benzene
Application of
Pesticides
Organophosphates, Carbamates, Pyrethroids
Gardening
Pesticides, Herbicides, Gasoline, Oil, Fertilizers
Cooking
Combustion products, Formaldehyde
Aerosol cans usage
Propane, Butane, Methylene propellants, Isobutane
Disinfectants
Sodium hypochloride, Quaternary ammonium salts,
Phenols, Pine oils
Smoking
Tobacco smoke
Furniture/carpets off
gassing
Formaldehyde, VOCs
Source:
Sterling et al., 1990.
Health effects due to exposure to VOCs
 Health effects due to exposure to VOCs at typical Industrial Environments are
derived from animal studies which can be related to humans
 Little is known about the chronic effects of a mixture of VOCs (particularly at
low concentrations)
 Indoor Environments (residences in particular) have different types of exposure
to the pollutant:
 High Concentration but for a short period
 Low concentration but for a longer period
 In short-term exposure individuals are exposed to one or a mixture of
compounds depending on their activity levels
Health effects due to exposure to
contaminants depends on:
 Exposure time
 Pollutant types
 Health status of the individual at the time of exposure
 Pollutant concentration (an important factor)
Health effects due to Aldehyde Exposure
Formaldehyde
 Formaldehyde is colorless but has distinct pungent odor that makes it
detectable (even at concentrations as low as 0.05ppm)
 Formaldehyde concentration is higher in mobile homes and houses with Urea
Formaldehyde Foam Insulation (UFFI)
 Formaldehyde has both acute and chronic health effects like: Irritation of eyes,
upper airway, etc
Health effects due to formaldehyde exposure at
various concentrations
0.0 - 0.5 ppm
None reported
0.05 - 1.5 ppm
Neurophisiological effects
0.05 - 1.0 ppm
Odor threshold limit
0.01 - 2.0 ppm
Irritation of eyes
0.1 – 25 ppm
Irritation of upper airway
5 – 30 ppm
Irritation of lower airway and pulmonary effects
50 – 100 ppm
Pulmonary edema, inflammation, pneumonia
> 100 ppm
Death
Source:
NAS, 1981.
Studies on formaldehyde exposure
1396 residents of UFFI Not reported
homes and 1395 of nonUFFI homes (Thun et
al.,1984)
Wheezing: e, 60%; ne, 10%;
Burning skin: e, 70%; ne, 10%;
70 employees in 7
mobile homes and 34
non-exposed employees
in 3 buildings
Mobile home: 0.24 –
0.55 ppm
Building: 0.05 – 0.11
ppm
Menstrual irregularities: e, 35%;
ne, none
Eye irritation: e, 55%, ne,15%;
Headache: e,80%; ne, 22%;
21 workers in mobile
homes and 18 workers
in buildings
Mobile home: 0.12 –
0.16 ppm
Building: not
reported
Eye irritation: e, 81%; ne, 17%;
Throat irritation: e, 57%; ne, 22%;
Fatigue: e,81%; ne, 22%;
Headache: e, 76%; ne, 11%;
Where: e – Exposed and
ne – Non-exposed.
Health Effects due to Exposure to Formaldehyde and
Ethers
 Formaldehyde at high concentration can cause buccal cavity cancer and
nasopharyngeal cancer in human beings
 Low concentrations can also be fatal or can cause serious threat to
health and the risk of developing cancer is:
 1 in 10,000 Exposed for 10 yrs at 0.07 ppm
 1 in 5,000 if exposed at 0.1 ppm
 The Ethers cause anesthetic effect in humans, which leads to pulmonary
edema, vomiting, headache and nausea
Health effects due to Exposure to high concentration
of ketones
 Narcosis
 Nausea
 Headache
 Dizziness
 Irritation of mucous membrane
 Loss of co-ordination
Effects of Formaldehyde exposure on human health
160
death
140
pulmonary edema, inflammation,
pneumonia
120
Series1
100
Series2
Series3
Series4
80
Series5
irritation of lower
airway and pulmo-nary effects
60
odor
threshold
limit
40
20
no effects
neurophysiologic
effects
0.05-1.5
Series7
irritation of
upper airway
Series8
irritation of eyes
0
0.0-0.5
Series6
0.05-1.0
0.01-2.0
1 0.10-25
5-30
50-100
over 100
conentration of formaldehyde in
PPM
Health effects due to exposure to Aliphatic and
Aromatic Hydrocarbons
 Propane and more complex hydrocarbons depress the central nervous system
and cause mild irritation of the mucous membrane
 Cyclic Hydrocarbons have same effect as the aliphatic hydrocarbons
 Aromatic Hydrocarbons cause:
 irritation of mucous membrane, eyes and respiratory system
 pulmonary edema
 pneumonitis
 Benzene, a hydrocarbon, is a human carcinogen
Health effects due to exposure to Chlorinated
Hydrocarbons
 High volatility of the chlorinated hydrocarbons leads to substantial exposure
through inhalation
 Chlorinated hydrocarbons cause
 Irritation to eyes
 Irritation to skin
 Irritation to respiratory system
 Severe functional
 Severe damage to the liver and kidneys
Changing exposure limits of Chlorinated Hydrocarbons
Pollutants
Year
1958
1960
Chloroform
100
50
Methylene chloride
500
Methyl chloride
50
Vinyl chloride
500
Trichloroethylene
200
100
Tetrachloroethane
200
100
1,2 – Dichloroethane
100
Methyl chloroform
500
200
Carbon tetrachloride
25
10
A1, human
A2 animal
Source:
Henschler, 1990.
(concentration
in ppm)
1970
1980
1990
B,10
200
100
B
100
B,A2,A1
50
B
50
20
B
B
B, suspected
Human
Health effects due to exposure to Alcohols
 Compounds like phenol and cresol cause
 Difficulty in swallowing
 Diarrhea
 Tremors
 Convulsions
 Ingestion of Methanol causes damage to the optical nerve leading to
blindness
Mixture of VOCs
 Chemicals are found in a room generally in a mixture form
 Synergistic interactions of pollutants leads to different chemical compounds
 Any building related health effects due to indoor pollutants is referred to as
Sick Building Syndrome (SBS) or Tight Building syndrome (TBS)
Exposure Limits
 Threshold limit Value (TLV) is the level of a chemical that ACGIH deems safe for
a worker to be exposed to day after day
 OSHA, ASHRAE recommended one-tenth of TLV as maximum allowed indoor
concentration
 Based on several studies American Industrial Hygiene Association (AIHA)
adopted 5 mg / m³ as a guideline for VOCs
 ASHRAE (62-1999) suggests the following air exchange rate’s :
-- Residential Facilities: minimum of 15 ft³ /person/ min
-- Commercial and Institutional facilities: 15 to 60 cf/person/min
Formaldehyde
 Formaldehyde, a major VOC, is released mainly from materials that contain
UFFA, a type of resin. These materials can include:
 Building materials
 Home/Office Furnishings
medium
density fiberboard
 particle board
 carpet
 electrical switches
 Formaldehyde is used in resins because of its following properties
 Excellent bonding properties
 Inexpensive
Formaldehyde uses and potential indoor sources
Products
Examples
Paper products
Grocery bags, wax paper, facial tissue, paper towels,
disposable sanitary products
Stiffness, wrinkle
resisters and water
repellents
Floor covering (rugs, linoleum, varnishes, plastics),
carpet backings, adhesive binders, fire retardants,
wrinkle free clothes, pressed clothes
Insulation
Urea Formaldehyde Foam insulation (UFFI)
Combustion devices
Natural gas, kerosene, tobacco smoke
Pressed-wood products
Plywood, particle board, decorative paneling
Other sources
Cosmetics, deodorants, shampoos, fabric dyes, inks.
Formaldehyde emission rates of several building
materials
Material
Emission rates (micro gms/m2 day)
Medium density fiberboard
17,600 – 55,000
Hardwood plywood paneling
1500 – 36,000
Particle board
2000 – 25,000
UFFI
1200 – 19,200
Softwood plywood
240 – 720
Paper products
260 – 680
Fiber-glass products
400 – 470
Clothing
35 – 570
Resilient flooring
< 240
Carpeting
0 – 65
Upholstery
0–7
(Source: NAS; Pickrell,1983; Matthews, 1985)
Formaldehyde
 The concentration of HCHO fluctuates with
 Seasonal variation of temperature
 Relative humidity, and
 Moisture content of several materials
 HCHO is produced during the various processes such as
 Operation of combustion appliances (gas or kerosene stove, fireplace etc.)
 Smoking
Formaldehyde concentration in homes resulting from combustion appliances
Winter
Summer
Combustion
sources
No. of
homes
Mean
(ppm)
Std.
Dev.
No. of
homes
Mean
(ppm)
Std.
Dev.
None
31
0.046
0.035
34
0.059
0.043
Woodstove
63
0.053
0.032
62
0.082
0.038
Kerosene heater
39
0.055
0.028
42
0.067
0.033
Kerosene heater
and woodstove
17
0.05
0.026
13
0.075
0.032
Smoker
33
0.046
0.025
25
0.055
0.031
Smoker and
woodstove
41
0.048
0.024
39
0.068
0.032
Smoker and
kerosene heater
32
0.042
0.018
32
0.054
0.026
Smoker,
woodstove and
kerosene heater
25
0.047
0.027
22
0.06
0.025
Source:
Hawthorne and Matthews, 1985
Sources of VOCs
 VOCs other than Formaldehyde are released from several other products such as
 Combustion products
 VOCs emitted as a result of incomplete combustion of fuel release
chemicals like methane, ethane, propane and hexane
 Wood also releases Polynuclear Aromatic Hydrocarbons (PAH)
 Tobacco smoke (depending on the number of cigarettes smoked)
Emissions of Organic Chemicals from Household Products
Emission (in ppm)
Compound
Adhesives
1,2Dichloroethane
0.8
Benzene
0.9
Carbon
tetrachloride
1.00
Chloroform
0.15
Coatings
Fabrics
Foam
Lubricants
0.75
0.6
0.7
0.2
0.18
0.10
0.04
0.20
0.07
1.00
0.50
0.02
12.54
0.30
65.0
0.10
0.03
0.10
0.10
Ethyl benzene
Limonene
Methyl chloroform
0.4
0.2
Styrene
0.17
5.20
Tetrachloroethylen
e
0.60
Trichloroethylene
0.30
0.09
Emission of Organic Chemicals from Household Products
Emission
Compound
Paints
Rubber
1,2-Dichloroethane
in ppm
Tape
Cosmetics
3.25
Benzene
Carbon
tetrachloride
Chloroform
0.90
Ethyl benzene
527.80
0.10
0.69
4.20
0.75
0.90
0.05
0.20
Limonene
0.40
Methyl chloroform
0.10
0.10
0.20
0.15
0.10
1.10
Tetrachloroethylene
0.20
0.08
0.70
Trichloroethylene
0.07
0.09
1.90
Styrene
deodorants
33.50
0.15
Emission of Organic Chemicals from Household Products
Emission
(in ppm)
Electrical
equipment
Misc. house
wares
Ink pens
0.02
1.10
0.40
Carbon tetrachloride
0.00
0.04
0.20
Chloroform
0.23
4.85
10.00
Ethyl benzene
0.80
Compound
Health &
beauty aids
1,2-Dichloroethane
Benzene
0.06
1.85
Limonene
1.00
Methyl chloroform
0.01
0.03
0.19
0.10
Styrene
0.17
0.05
0.02
0.30
Tetrachloroethylene
Trichloroethylene
1.80
0.05
0.11
0.01
2.00
0.06
0.07
Emission of Organic Chemicals from Household Products
Emission (ppm)
Compound
Paper equipment
Photo film
Photo
equipment
1,2-Dichloroethane
Benzene
0.03
Carbon tetrachloride
Chloroform
1.51
0.04
2.50
0.10
Ethyl benzene
2.50
0.10
10.50
0.13
0.08
1.90
0.04
0.10
0.03
0.13
Limonene
Methyl chloroform
0.26
Styrene
Tetrachloroethylene
0.42
Trichloroethylene
0.10
Source: Ozkaynak et al., 1987.
Sources of VOCs
Carpets and paints
 Carpets and paints are large contributors and cover nearly 95% of room
surface area
 VOCs are emitted by the use of oil-based paints
 Carpets emit VOCs at first but gradually VOC emission rates diminish
 Newly carpeted room should be properly ventilated for several days after
installation, or carpets can be pre-ventilated in a humidity controlled
warehouse
Sources of VOCs
Water
 During treatment of water before supply under go several processes.
 Common by-products of this treated water are:
 Chloroform
 Carbon tetrachloride, and
 1,2,3-trichloropropane
Human beings
 Acetone :1200 * 10 E (-6) / m³
 Ethanol :240 mg/m³
Emission rates of organics by humans
Emission rate
Organic compounds
Typical conc.(389 people in
class (ppb))
Lecture class
225 people
During examination
Acetone
20.6 +/- 2.8
50.7 +/- 27.3
86.6 +/- 42.1
Acetaldehyde
4.2 +/- 2.1
6.2 +/- 4.5
8.6 +/- 4.6
Acetic acid
9.9 +/- 1.1
19.9 +/- 2.3
26.1 +/- 25.1
Allyl alcohol
1.7 +/- 1.7
3.6 +/- 3.6
6.1 +/- 4.4
Amyl alcohol
7.6 +/- 7.2
21.9 +/- 20.8
20.5 +/- 16.5
Butyric acid
15.1 +/- 7.3
44.6 +/- 21.5
59.4 +/- 52.5
Diethylketone
5.7 +/- 5.0
20.8 +/- 11.4
11.0 +/- 7.7
Ethyl acetate
8.6 +/- 2.6
25.4 +/- 4.8
12.7 +/- 15.4
Ethyl alcohol
22.8 +/- 10.0
44.7 +/- 21.5
109 +/- 31.5
Methyl alcohol
54.8 +/- 29.3
74.4 +/- 5.0
57.8 +/- 6.3
Phenol
4.6 +/- 1.9
9.5 +/- 1.5
8.7 +/- 5.3
Toulene
1.8 +/- 1.7
7.4 +/- 4.9
8.0
Carbon monoxide
48,400 +/- 1200
Ammonia
32.2 +/- 5.0
Hydrogen sulphide
2.73 +/- 1.32
2.96 +/- 0.68
Carbon dioxide
642,000 +/- 34,000
930,000 +/- 52,000
Source: Wang, 1975
Most commonly used analytical type air quality
monitoring equipment
Personal monitors
 Lightweight monitors convenient to carry and to handle
Portable monitors
 These can moved during sampling
Stationary monitors
 These can operated only from a fixed place
Principles followed by collectors during data
collection
 Air Displacement
 Condensation

Air is passed through a U-tube followed by subsequent cooling of the
sample
 Gas washing or Absorption

The contaminated air or the sample is passed (bubbled) through a
where it may dissolve or react with the liquid

Distilled water is used for readily soluble gases
liquid,
Principles followed by collectors during data
collection
Adsorption: Frequently used Solid adsorption media are

Activated carbon

Silica gel

Sieves

Tenax-GC, Tenax-TA

XAD-2, XAD-4

Chromosorb 101, 102 and 103 etc.
Principles followed by collectors during data
collection
Adsorption
 The key factors for successful use of these adsorbents are:


Cleaning of the sorbent tube to remove background contamination by

Heating to high temperatures in vacuum

Flowing small quantity of inert gas
Accurate determination of the sampling rate
Analytical methods used
 Colorimetric and spectrometric methods are used to quantify a pollutant
 Colorimetric method is commonly used for measurement of Formaldehyde
 A method referred to as Acid bleached pararosaniline method:
 Equivalent to the chromo tropic acid method
 Twice as sensitive
Most commonly used detectors for analysis
Thermal conductivity detector (TCD)
 Suitable inorganic gases as it measures changes in thermal conductivity
Hot wire detector (HWD)
 Measures thermal conductivity and is also suitable for inorganic gases
Flame Ionization Detector (FID)
 Detects difference in flame ionization due to combustion suitable for:

Aliphatic compounds

Aromatic compounds
Most commonly used detectors for analysis
Electron Capture Detector (ECD)
 Measures the current flow between the electrodes and is suitable for chlorinated
hydrocarbons
Flame Photometric Detector (FPD)
 Measures light from excited state of Sulphur and Phosphorous compounds in
hydrogen flame
Mass Selective Detector (MSD)
 It is suitable for most indoor pollutants
 This method provides quantitative analysis, and
 Identifies different chemicals in a mixture
Source control
 Selection of the products that emit very less VOCs
 Concentration due to selected building materials should be below 0.05 ppm
 Substitution of the material with a material of similar properties having low
emission rates
 Avoiding the materials containing formaldehyde (like UFFI, Ammonium
Sulphite)
Suggested Emission rates of products in building
Materials
Emission rates
Flooring material
0.6
Floor coating
0.6
Wall material
0.4
Wall coating
0.4
Movable partitions
0.4
Office furniture
0.25 mg/h/workstation
Office machines (central)
0.25 mg/h/m3 of space
Ozone emission
0.01 mg/h/m3 of space
Office machines (personal)
2.5 mg/h/workstation
Ozone emission
0.1 mg/h/work station
(Source : Tucker, 1990.)
Ventilation
Types of ventilation
 Infiltration of outdoor air
 One of the common cost effective methods
 Ineffective if outside air or the in filtered air is itself polluted
 Natural ventilation
 This happens when all the doors and windows are properly opened
 This is the most effective method as there is constant air inflow
 The only disadvantage is the increase in the heating or cooling costs
Ventilation
 Mechanical ventilation
 Use of HVAC system (normally suitable for non-residential places)
 Advantageous over other types of ventilation
 Energy for heating or cooling can be recovered from the exhaust air
 Local Ventilation
 This method produces a low pressure around the source using a blower fan
 This method is a disadvantage if the source is of continuous type
Air Cleaning
Removal by Catalytic Converters
 Pollutants found in the air can be converted to less
harmful gas using the
catalytic converters
 Some catalysts used to remove Formaldehyde are:
 Purafil
 Activated carbon
 Alumina oxide
 Ammonia fumigation is the method employed for formaldehyde removal
(particularly for mobile homes)
Air Cleaning
Removal by absorption
 Used for organic pollutant removal from indoor air
 Experiments showed removal of formaldehyde up to 63% (but were not
tested practically)
Removal by adsorption
 Gases are attracted on to the solid and they remain until reversed by
applying vacuum or heat
 Efficiency of adsorbant should be known before using a activated solid
material for a particular pollutant