How to Perform Sampling
Where to Send Samples
How to Interpret Test Results
Caltex International Ltd.
60 Presidential Plaza, Ste 1405
Syracuse, NY 13202
(315) 425-1040
How to Perform Sampling
Where to Send Samples
How to Interpret Test Results
It is essential to inform the customer about what mold remediation is and the fact that part
of your service is mold testing. The customer must understand why it is essential to have
mold testing performed.
It is essential to have mold testing and sampling performed because:
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Mold spores are too small to be seen and conclusively identified as a particular
species of mold.
The extent of contamination cannot be determined without sampling and testing.
Species of mold have varying health ramifications.
It is essential to have a pre-remediation air sampling to compare to the post
remediation air testing (also compared to outdoor air quality).
To educate the customer particularly if they are mold sensitive and to take
appropriate action to protect the customer and your staff members.
Prior to performing the sampling, it is important to assess the building environment.
Where is mold visually evident? How large a moldy area is it? Is the mold cover
particularly thick? Does the color vary from location to location? Do you suspect hidden
mold because you saw structural damage from doing an outside inspection of the
structure? Is a moldy odor particularly strong in one location versus another location?
The contractor may have to pull away sections of wallboard, insulation, or other materials
to properly assess if there is hidden mold or not. Common areas for hidden mold are
behind basement wallboard materials, under sinks, tubs, showers, behind wall and attic
insulation and/or wallboard materials and many more!
Taking samples of each mold that appears different is a good idea. Taking more samples
in areas of larger mold spread is also beneficial. The contractor gets enough good
samples for the laboratory to test.
The 2 main types of sampling that will be reviewed are air testing and surface sampling.
Surface sampling entails taking physical samples of mold growth from growth locations.
A tape sample can be taken by placing the tape on the mold covered surface. The mold
then adheres to the tape. The tape is put onto a slide and the analyzed by the laboratory
which generates a report documenting the type of mold. Tape sample results only reflect
the type of mold. To determine the extent of mold contamination, air sampling will have
to be performed. We will discuss this later in this section.
Another method of gaining surface samples for testing is to perform a swab test. A swab
is wiped across the moldy surface section and then placed on an agar plate (this plate then
grows the mold into viable colonies). The mold testing laboratory identifies the type of
mold.
It is also essential to perform pre-remediation air sampling. This will determine the levels
of spores in the air. Since mold releases spores into the air and spores travel on air
currents, you will know the extent of the contamination by taking air samples from
various areas in the structure. It is essential to use both bulk sampling (taking physical
samples of the mold form the growth source) and air sampling because NOT all types of
mold go airborne easily (refer to section on types of mold). Basically air sampling
involves selection and use of one of the following methods:
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Hole impaction
Sieve impaction
Centrifugal
Filtration
Gravity based
Material settlement
Multiple hole impaction
Liquid impingement
A culture methodology has the air flow impacting upon a culture disk. the viable spores
are grown into colonies, the type of mold(s) identified, and based on the air flow the
amount of mold colonies per cubic meter of air can be mathematically determined. This
method is helpful because the contactor gets a definitive answer as to what type of mold
he or she is dealing with.
Air sampling using a sticky source, allows the laboratory to take an exact count of spores
in the air per cubic meter of air. This provides an accurate answer to the quality of air in
the structure. This is helpful if homeowner’s have complained about not feeling well and
respiratory problems. Either way, air sampling is essential to perform pre-remediation
and post-remediation combing with mold remediation and repair of the source of the
moisture problem to ensure a job well done.
The samples are sent to the laboratory for testing. Swab and culture sampling typically
take several more days to get results because the mold must have time to grow into
colonies. Air impact on sticky substrate provides a mold count and takes less time to get
results. The customer should have a basic time frame as to when results will come in.
Charges for mold sampling usually range from $120.00-$125.00+ based on the
complexity of the project and the number and type of samples taken. This average price
also takes into account communicating the results with the customer and the cost and
labor of 2 visits.
When the report comes back from the laboratory, the contractor must communicate the
type of mold that is present and from the air sampling the amount of spores per cubic
meter of air. The contractor should compare the indoor air quality to what normal outdoor
air quality conditions in terms of the number of spores per cubic meter of air are. It is
essential for the homeowner to know how their indoor air quality compares to normal
outdoor air quality (this is the post remediation test-to have the post remediation indoor
air quality test the same or better than normal outdoor air quality).
If the laboratory and contractor have determined that the source of the problem is mold
infestation, the contractor will have to commence a mold remediation plan by thoroughly
assessing the sources of the moisture problem and ask the following questions in
developing the start of the mold remediation plan.
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What structural repairs are involved? How will this be done? Who will do this?
Where is hidden mold located? Is the structure compromised? What materials
must be removed to get at he hidden mold?
How many rooms are involved?
How will I seal the remediation zone(s)
How many cleaning stations will need to be set up?
What materials can be cleaned and dried?
What materials must be discarded?
How much time and how may staff members will this project require?
What are my overhead costs-materials, time labor, wages and benefits, insurance
costs etc.?
The contractor must plan for all of the issues above and more in planning to prepare a
quote to discuss with the customer.
How To Interpret Air Sampling Results?
Air sampling devices have different flow rates. Different air samplers have different rates
of efficiency. It is important to use the same exact type of air samplers. It is essential to
compare apples to apples. Never compare results from different air sampling equipment
types and never take samples for different durations of time and compare results.
Several common types of air sampling devices are as follows:
Spore traps:
 Air-O-Cell cassettes
 MCE filter cassettes
 Allergeno samplers
 Burkhard samplers
These types of air samples collect spores on a receiver or membrane.
When this type of sample is submitted to a laboratory for testing, all of the mold and
fungus parts are counted and identified. The accuracy of total spore count results is very
similar to that of the culture plate method. Culture plates usually result in less
mold/fungal collection than a spore trap method. Why is this? Collection via culture plate
only grows viable spores. Therefore, non-viable or dormant spores cannot grow into
colonies on the plate. The advantage of using a culture plate methodology is that the
types of mold/fungus can be properly identified.
How Are Airborne Mold/Fungus Spores Results Arrived at
From the Spore Counting Method?
Your initial site investigation and visual observations are essential to this process. The
contractor should be mapping out the locations of water damage, extent of damage, types
of materials damaged, humidity issues, building history, and more. Via this means, the
contractor can correlate the mold testing results with the location issues where the
samples derived. This can be used in the process of making remediation
recommendations.
Follow the steps herein. The contractor may not need to use all of the steps. If a step is
not applicable to your case, go on to the next step.
1. If there is a large sampling of airborne spores from the total spore counting
method, you might be able to define what is considered a low, moderate or high
level to screen your results. This type of data should only be used for performance
evaluation and cannot be used as criteria for a health evaluation.
2. Compare total concentrations from outdoor, indoor, areas without apparent issue,
and areas with mold/spore issues. Indoor mold/spores levels should be less than
outdoor air quality. However, remember that building with many open
windows/door especially in the summer and better weather seasons or locations
without can have spore levels that are higher than outside air levels. Locations
without spore growth should generally have lower spore counts than areas with
actual/suspected spore growth.
3. Compare spore type and species, indoor versus outdoor air quality, and involved
versus non-involved area. Large indoor spaces may not always reflect the same
spore/mold types as outdoors because of the large space over which the spores
may be spread.
4. Compare the data from involved locations to assess what spores are consistently
found. If the samples from all involved areas indicate that a consistent level of
spores is found, then the mold source is probably nearby.
5. Look for fungal spores that are usually associated with water damage. Common
spores associated with water damage are: Chaetomium, Stachybotrys, Menoniella,
Ulocladium. and Eurotium. Reproductive structures of spores such as ascus,
conidophores, and ascomata can indicate active mold growth due to water
damage, condensation, or high humidity levels. Eurotium, for example, often
indicates high humidity, condensation problems, and poor ventilation. Aspegillus
and Penicillium types of spores are common both indoor and outdoors. However,
if they are found in higher levels indoors, this is indicative of a water damaged
environment.
6. Low levels of spores in winter indoors do not indicate a healthy indoor air quality
environment. In winter, water freezes and temperatures drop thereby putting mold
and its spores into dormancy and a non-reproductive state. This can significantly
change in spring and summer when temperatures are warm and leaks have
unfrozen. Ex: A leaky moldy basement does not actively leak at 10 degrees F or
appear as smell and moldy until the spring thaws hit.
7. If Stachybotrys spores are detected consult the “Guidelines on Assessment and
remediation of Stachybotrys atra in Indoor Environments” by the NYC
Department
of
Health.
This
can
be
found
at
www.ci.nyc.us/html/doh/epi/moldrpt1.html
8. Be sure to correlate customer complaints, site inspection, and lab results to
determine if there is mold/fungal growth. If there is mold/fungal growth, there is a
moisture/water problem nearby. The source of this moisture problem must be
fixed so that it does not recur.
9. Understand the background of the type(s) of spores found and identified in the
laboratory results. Some spores such as Eurotium are xerophobic and grow where
there is low water activity. Others such as Chaetomium, Memnoniella,
Stachybotrys, and Ulocladium grow where there is a great deal of water present.
Bulk Sampling Technique
Bulk sampling can be performed on the following materials (but not limited to):
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Carpet Fibers
Drywall Materials
HVAC System Liners/materials
Sheetrock
1. Use a knife to cut out the section to be sent out bulk sampling. Be sure to wear
health care type of gloves for personal protection and to protect the sample.
Always alcohols swab your cutting tool both before and after taking the bulk
sample.
2. Cut a 1-4 square inch sample and put this in a zip lock bag. Be sure to be gentle
when cutting out the sample so that you do not disturb the spores/mold/fungus
source. Label the sample and record it on the sample sheet. Record site, sample
location, sample size, time and date.
3. Send the samples to the laboratory ASAP. If the bulk samples are damp or moist
ship them in ice by overnight courier. Contact the laboratory and inform then that
wet samples are on their way and to get them tested immediately. Verify that you
send all samples with the data sheet and chain of custody to the lab.
How to Perform Spore Trapping Samples?
Spore traps are set up to collect a range of airborne fungal and mold spores. Different
spore trapping devices have different flow rates and different total volumes. Always be
sure that the same type of spore trap samplers is used for indoor and outdoor air
sampling. If the contractor does not do this and then compares samples, the results will be
incorrect.
1. Attach the exit end of the cassette to the tube and air pump.
2. Be sure to record the location and all required chain of custody information.
3. Out the cassette and pump down on a stable surface in the location of where the
air sampling is to be done.
4. Do not disturb the area while the sampling is taking place.
5. Set the sampling time (all samples should be set for the same time period for
apples to apples comparison)
6. When the sampling is completed, re seal the sample inlet slit and remove the
sample from the pump mechanism.
7. Send the sample to the laboratory with the chain of custody documentation (keep
copy for your records).
Wipe and Swab Sampling
This type of sampling should only be used on hard surfaces. Soft surfaces will require a
different sampling method such as vacuum suctioning into cassettes.
To perform wipe/swab sampling do the following:
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Follow the directions on your wipe/swap kit but first moisten the swab.
Take the sample by wiping the surface.
Wipe 1 square or 4 square inches.
If the surface looks significantly dirty, double the surface swabbing area.
Properly label the samples. This should include the size of each area sampled.
Send a copy of the data sheet with the samples.
6. Send the samples to the lab via overnight courier. Ice packs may be used and are
often helpful is retaining a viable sample.
7. The laboratory will analyze the samples and send you the results as soon as they
are available.
Mold Testing Laboratories
Mold testing laboratories can be found in the Yellow Pages of your local phone book.
Galson Laboratories at 888-432-5527 provides kits .
Galson requires that microbiological samples be shipped via overnight courier in a cooler
with blue ice. The utilize potato dextrose agar (PDA) for fungal cultures and Trypticase
Soy agar (TSA) for bacteria testing.
Please refer to the Galson Laboratories Handouts. These handouts document how to take
a sample using different sampling devices, how to send in samples, equipment rentals,
and much more!
SKC at www.skcinc.com also rents equipment and provides a full range of testing
services.