Test Choices to Screen for Mold in Fiberglass in Insulation
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Choices of fiberglass mold test alternatives for field and laboratory investigation of building mold contamination
Testing or inspecting for moldy building insulation or moldy heating or air conditioner duct insulation
Detailed procedural guide for testing building insulation for mold contamination
When should we test or not test insulation for mold?
Qualitative vs. quantitative tests for insulation mold
Questions & answers about methods for testing for the presence of mold contaminants in fiberglass or other building insulation products

Fiberglass insulation mold contamination test details: this document discusses choices of test methods to screen for toxic or allergenic mold contamination in fiberglass building insulation in residential and light-commercial buildings. Mold is often found in basement fiberglass insulation, crawl space fiberglass insulation, fiberglass wall insulation, heating or cooling duct fiberglass insulation, and attic or roof insulation in buildings which have either been wet or have been exposed to high levels of mold from other sources.

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How to Test Building Insulation for Mold Contamination

This article explains how to find or test for moldy insulation in buildings, the probable cause of mold contamination in building insulation, and how to recognize conditions that make that problem likely in a particular case. Our page top photo shows a Burkard personal air sampler that with clever manipulation can be used to test fiberglass building insulation for contaminating particles including mold, insect fragments, pollen, or other debris.

More details about just how fiberglass mold tests are conducted in the field are found at TEST PROCEDURE for MOLD in FIBERGLASS. This website discusses health hazards associated with moldy fiberglass in buildings, with focus on fiberglass insulation, fiberglass fragments, fiberglass in heating and air conditioning duct work, and invisible but toxic mold growth in fiberglass which has been wet, exposed to high humidity, or exposed to other moldy conditions.

Readers of this document on mold hazards in fiberglass insulation should see How to Test for Mold in Insulation and also read INSULATION MOLD on how to locate and test for moldy insulation in buildings, and for a technical discussion of use of vacuum sampling methods for inspecting building insulation, see Vacuuming exposed insulation. To avoid further mold contamination also see MOLD RESISTANT CONSTRUCTION and MOLD PREVENTION AFTER FLOODING.

See Attic Moisture or Mold Sources for a discussion of common sources of moisture in attics that can cause moldy insulation, and similarly, see BASEMENT LEAKS, INSPECT FOR for the same problem in basements. Readers ducting cool air through a crawl space should also see CRAWLSPACE MOLD ADVICE.

Question: How should we sample fiberglass insulation for mold when investigating a building?

I believe that there is mold that is not visible to the eye, but how do you confirm that it is there? Send a piece of the insulation to a lab for analysis? I’m a mold inspector in Minneapolis, Minnesota and we have a lot of damp insulation in basements here.

Sometimes I see spots on the insulation and know that there is obvious mold, but I have long suspected (based on smell and moisture readings) that some mold might not be visible to the eye. Is it just that it is in early growth stage so the colonies are too small to see?

And again, how do you verify that this is the case – by samples submitted to the lab? I was on the site searching for information on mold in insulated ducts. - Vickie Swenson, CRMI Minnesota Mold Inspection (612) 508-2742

Our photo of clean-looking insulation in a basement ceiling (above left) does not provide evidence that insulation testing was necessary for that building. But a case history of occupant complaints, a wet basement, and previous storage of moldy materials in the basement that had been removed at the time of our inspection led us to test and confirm that this insulation was severely contaminated with Penicillium sp. mold.

Answer: Detailed Description of Methods for Testing Building Insulation for Mold

You are quite right that it can be impossible to see mold in some materials including fiberglass insulation. Sometimes fiberglass looks very very clean to the naked eye, but is chock full of Aspergillus or Penicillium.

There are several similar ways to test insulation that does not already give visual evidence of a mold problem.

Air Sampling Cassettes for Insulation Mold Test

We use an air sampling cassette such as an Air-o-Cel or Allergenco unit with a vacuum pump set to move air at the proper flow rate for the cassette (typically 10 lpm). The sampler is held 1-4 inches away from the insulation and then with the pump running we poke or agitate the suspect insulation to stir a particle release.

The sample interval needs to be short - often just 5-20 seconds in duration since otherwise you risk overloading the cassette with fiberglass particles.

At ACCURACY OF VARIOUS MOLD TEST METHODS we include photos of particle traces on microscope slides that can help you recognize when a dust sample is overloaded and thus hard to analyze in the lab.

Our photo (above left) shows a more complicated version of this test about to start. In this case we were using two air sampling pumps and two different brands of sampling cassettes in order to compare their behavior during dust sampling. In the foreground you can just make out a special timer-switch that we used to turn on and off both pumps simultaneously.

If you are in doubt or inexperienced, try making three sample cassettes of 5, 10, and 20 second durations, agitating the insulation about the same degree in each case and keeping about the same distance.

The time and distance are not critical as long as we make clear that this is a qualitative test for the presence or absence of high levels of mold or other particles in the insulation, not a quantitative test.

Burkard Personal Air Sampler and Prepared Slide for Insulation Mold Test

A second method for testing fiberglass insulation that we have used with good results was to run a Burkard personal air sampler with a prepared collection slide mounted in the device for a 15-second interval, holding the sampler one to six inches away from the insulation during agitation of the insulation itself.

You can simply use a pencil to poke the insulation during sampling. As with the air sampling cassette approach above, make several test samples at different sampling durations to be sure you have a good sample that is not overloaded.

Alternative, low-cost Air Pumps for Building Insulation Mold Testing

While we prefer using a calibrated instrument for pulling particles from building insulation to screen for mold contamination, considering that a reasonable mold contamination test is qualitative and that precise mold counts are inappropriate (and would be misleading), as long as your air pump or vacuum device produces a flow-rate within the operating range of your sampling cassette or slide, you can use less costly devices such as the keyboard vacuum pump shown here.

Watch out: the airflow rate of portable battery operated pumps such as shown here varies widely from device to device as well as depending on battery condition.

For field use in testing insulation, we tested ten low-cost portable pumps in our forensic laboratory, selecting a subset that consistently delivered 10-15 LPM with fresh batteries .

Constructing a Clean Test Chamber to Screen Insulation for Mold

In the laboratory, if we receive a bulk sample of suspect insulation, in addition to inspecting the insulation itself in the stereo microscope and high power transmitted light forensic microscope, we sometimes use a third sampling method that is most suitable for a variety of suspect, perhaps dirty and loose materials.

We construct a test chamber using a cardboard box lined with a new clean plastic garbage bag.

The bag lines the box, the sample is placed into the box, the box is sealed. We cut an opening sufficient to admit or affix our air sampling cassette, then we agitate the box for 30 seconds before pulling a vacuum sample from the box itself.

This method also can reduce overloading the sample with fiberglass particles.

Quantitative Analysis of Insulation Samples for Mold Contamination

It is possible to perform quantitative analysis of insulation or other fibrous materials or dust samples for mold contamination using a wash and filter method that collects most particles from the insulation sample into a liquid for further processing and particle counting.

We do not agree that the apparent accuracy of this method is real, and we suspect that except for controlled technical studies it is not appropriate.

Fungal contamination within a fiberglass sample varies widely even within the same building area depending on proximity to a leak
Fungal contamination within fiberglass insulation in a building varies by distance to an external airborne mold source such as moldy contents stored in a basement below a fiberglass-insulated ceiling
Fungal contamination in fiberglass insulation in a building will vary by other factors such as insulation age, density, installation details, presence or absence of vapor barriers, air movement patterns, etc.

Therefore a quantitative analysis of mold spores per cubic inch, meter or other volume of fiberglass insulation may be very precise (lots of decimal places) but inaccurate as an estimator of size of the problem mold reservoir.

Should All Building Insulation be Tested for Mold?

No.

We do not recommend testing all insulation for mold. The decision to test insulation for mold needs to be made based on a careful building inspection and case history, including visual evidence of leaks or the presence of exposed fiberglass over an area known to be or have been subject to a large mold contamination problem or a mold remediation project. See WHEN to TEST INSULATION for MOLD

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Questions & answers about methods for testing for the presence of mold contaminants in fiberglass or other building insulation products.

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INSULATION MOLD
  Mold in Fiberglass Insulation
  Mold on Books, Book Conservation
  Mold on Fiberboard Insulating Sheathing
  MOLD PREVENTION AFTER FLOODING
  MOLD RESISTANT CONSTRUCTION
  Mold in Foam Insulation
  Moldy insulation may look clean
  Why does mold grow in fiberglass?
  When to test insulation for mold
  How to Test for Mold in Insulation
  References, Fiberglass Hazards
  Vacuuming exposed insulation

BASEMENT MOLD includes examples of moldy fiberglass insulation found in basements
CRAWLSPACE MOLD includes additional examples of moldy fiberglass insulation found in crawl spaces
CRAWL SPACE DRYOUT PROCEDURES discusses how to dry out crawl spaces to prevent mold growth

Fiberglass building insulation and HVAC duct work insulation hazards
Fiberglass carcinogenicity: Glass Wool Fibers Expert Panel Report, Part B - Recommendation for Listing Status for Glass Wool Fibers and Scientific Justification for the Recommendation", The Report on Carcinogens (RoC) expert panel for glass wool fibers exposures met at the Sheraton Chapel Hill Hotel, Chapel Hill, North Carolina on June 9-10, 2009, to peer review the draft background document on glass wool fibers exposures and make a recommendation for listing status in the 12th Edition of the RoC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.
Fiberglass insulation mold: occurrence of mold contamination in fiberglass insulation can be impossible to see with the naked eye, but can be significant
[4] Thanks to reader Vickie Swenson, CRMI, Minnesota Mold Inspection (612) 508-2742, for discussing methods for sampling fiberglass insulation for mold contamination, June 2010 . Ms Swenson can be contacted by email to eagletree@frontier.com
[5] Ahearn, D.G., S A Crow, R B Simmons, D L Price, J A Noble, S K Mishra and D L Pierson, "Fungal colonization of fiberglass insulation in the air distribution system of a multi-story office building: VOC production and possible relationship to a sick building syndrome", Journal of Industrial Microbiology & Biotechnology, Volume 16, Number 5 (1996), 280-285, DOI: 10.1007/BF01570035. Abstract:
Complaints characteristic of those for sick building syndrome prompted mycological investigations of a modern multi-story office building on the Gulf coast in the Southeastern United States (Houston-Galveston area). The air handling units and fiberglass duct liner of the heating, ventilating and air conditioning system of the building, without a history of catastrophic or chronic water damage, demonstrated extensive colonization with Penicillium spp and Cladosporium herbarum. Although dense fungal growth was observed on surfaces within the heating-cooling system, most air samples yielded fewer than 200 CFU m–3. Several volatile compounds found in the building air were released also from colonized fiberglass. Removal of colonized insulation from the floor receiving the majority of complaints of mouldy air and continuous operation of the units supplying this floor resulted in a reduction in the number of complaints.
[6] Ahearn, D.G., S.A. Crow, R.B. Simmons, D.L. Price, S.K. Mishra and D.L. Pierson, "Fungal Colonization of Air Filters and Insulation in a Multi-Story Office Building: Production of Volatile Organics", Current Microbiology Volume 35, Number 5 (1997), 305-308, DOI: 10.1007/s002849900259, Abstract:
Secondary air filters in the air-handling units on four floors of a multi-story office building with a history of fungal colonization of insulation within the air distribution system were examined for the presence of growing fungi and production of volatile organic compounds. Fungal mycelium and conidia of Cladosporium and Penicillium spp. were observed on insulation from all floors and both sides of the air filters from one floor. Lower concentrations of volatile organics were released from air filter medium colonized with fungi as compared with noncolonized filter medium. However, the volatiles from the colonized filter medium included fungal metabolites such as acetone and a carbonyl sulfide-like compound that were not released from noncolonized filter medium. The growth of fungi in air distribution systems may affect the content of volatile organics in indoor air.
[7] Price,D. L., R. B. Simmons, I. M. Ezeonu, S. A. Crow and D. G. Ahearn, "Colonization of fiberglass insulation used in heating, ventilation and air conditioning systems", Journal of Industrial Microbiology & Biotechnology Volume 13, Number 3 (1994), 154-158, DOI: 10.1007/BF01584000, Abstract: The number of fungal species colonizing thermal and acoustic fiberglass insulations used in heating, ventilation, and air conditioning (HVAC) systems was fewer than that obtained from initial direct culture of these insulations. The colonization, determined by the microscopic observation of conidiophores with conidia, was primarily of acrylic-latex-facing material, but eventually the fungi permeated the fiberglass matrix. Isolates of Aspergillus versicolor were most often obtained from non-challenged insulation, whereasAcremonium obclavatum appeared to be the primary colonizing fungus in high-humidity (>90%) challenge chambers. At a lower humidity (about 70%) Aspergillus flavus was one of the more prominent fungi. Not all duct liner samples were equally susceptible to colonization and duct board appeared relatively resistant to colonization.
[8] Simmons, R. B. and S. A. Crow, "Fungal colonization of air filters for use in heating, ventilating, and air conditioning (HVAC) systems", Journal of Industrial Microbiology & Biotechnology Volume 14, Number 1 (1995), 41-45, DOI: 10.1007/BF01570065, Abstract:
New and used cellulosic air filters for HVAC systems including those treated with antimicrobials were suspended in vessels with a range of relative humidities (55–99%) and containing non-sterile potting soil which stimulates fungal growth. Most filters yielded fungi prior to suspension in the chambers but only two of 14 nontreated filters demonstrated fungal colonization following use in HVAC systems. Filters treated with antimicrobials, particularly a phosphated amine complex, demonstrated markedly less fungal colonization than nontreated filters. In comparison with nontreated cellulosic filters, fungal colonization of antimicrobial-treated cellulosic filters was selective and delayed.
[9] Ifeoma M. Ezeonu, Daniel L. Price, Sidney A. Crow and Donald G. Ahearn, "Effects of extracts of fiberglass insulations on the growth of Aspergillus fumigatus and A. versicolor", Mycopathologia Volume 132, Number 2 (1995), 65-69, DOI: 10.1007/BF01103777 , Abstract:
Water extracts of thermal and acoustic fiberglass insulations used in the duct work of heating, ventilation and air conditioning (HVAC) systems supported germination of conidia and growth of Aspergillus versicolor (Vuillemin) Tiraboschi 1908–9 and Aspergillus fumigatus Fresenius 1863. Urea, formaldehyde and unidentified organics were detected in the extracts. Formaldehyde in concentrations similar to those found in the extracts restricted the growth of both species in enriched media. A. versicolor, the more common species associated with fiberglass insulations, was more resistant to formaldehyde than A. fumigatus.

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.
Environmental Health & Investigation Bibliography - our technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
Adkins and Adkins Dictionary of Roman Religion discusses Robigus, the Roman god of crop protection and the legendary progenitor of wheat rust fungus.
Kansas State University, department of plant pathology, extension plant pathology web page on wheat rust fungus: see http://www.oznet.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Leaf%20Rust.asp
"A Brief Guide to Mold, Moisture, and Your Home", U.S. Environmental Protection Agency US EPA - includes basic advice for building owners, occupants, and mold cleanup operations. See http://www.epa.gov/mold/moldguide.htm
US EPA - Mold Remediation in Schools and Commercial Building [ copy on file as /sickhouse/EPA_Mold_Remediation_in_Schools.pdf ] - US EPA
US EPA - Una Breva Guia a Moho - Hongo [on file as /sickhouse/EPA_Moho_Guia_sp.pdf - - en Espanol

Fiberglass in buildings: hazards, testing, cleanup, prevention: references & products

For more information about fiberglass as an indoor air quality concern see:

Asbestos: How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials (Asbestos is not fiberglass and vice versa).
BASEMENT MOLD includes examples of moldy fiberglass insulation found in basements
CRAWLSPACE MOLD includes additional examples of moldy fiberglass insulation found in crawl spaces
Duct System Defects
Fiberglass in Indoor Air, HVAC ducts, and Building Insulation, Indoor Air Quality Investigations, building insulation and HVAC duct work insulation hazards
FIBERGLASS HAZARDS
Fiberglass Particle Identification in the Fiberglass Test Laboratory
Fiberglass References - Government Agencies & Authorities list of public documents on fiberglass
Goodman Gray Flex Duct Deterioration and Failures
INSULATION INSPECTION & IMPROVEMENT
Insulation Identification Photographs - Fiberglass insulation photos, yellow, pink, green, white fiberglass identification in building attics, walls, ducts, other locations
Insulation Identification Photographs - Cellulose insulation photos, Mineral wool insulation photos, rock wool insulation photos, cotton insulation photos, balsam wool insulation photos
Insulation Identification Photographs - Vermiculite insulation photos
Lab Identification of Fiberglass photographs and text assist in laboratory identification of fiberglass fibers and fragments in air, dust, or material samples in the laboratory using forensic microscopic techniques.
Mold in Fiberglass building insulation, when, why, and how fiberglass becomes a reservoir of problem mold in buildings.
AIR FILTERS, OPTIMUM INDOOR
Owens Corning Flex Duct Deterioration and Failures
World Trade Center Dust Particle Identification
Fiberglass carcinogenicity: "Glass Wool Fibers Expert Panel Report, Part B - Recommendation for Listing Status for Glass Wool Fibers and Scientific Justification for the Recommendation", The Report on Carcinogens (RoC) expert panel for glass wool fibers exposures met at the Sheraton Chapel Hill Hotel, Chapel Hill, North Carolina on June 9-10, 2009, to peer review the draft background document on glass wool fibers exposures and make a recommendation for listing status in the 12th Edition of the RoC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC. The National Institute of Environmental Health Sciences is one of the National Institutes of Health within the U.S. Department of Health and Human Services. The National Toxicology Program is headquartered on the NIEHS campus in Research Triangle Park, NC.
Following a discussion of the body of knowledge, the expert panel reviewed the RoC listing criteria and made its recommendation. The expert panel recommended by a vote of 8 yes/0 no that glass wool fibers, with the exception of special fibers of concern (characterized physically below), should not be classified either as known to be a human carcinogen or reasonably anticipated to be a human carcinogen. The expert panel also recommended by a vote of 7 yes/0 no/1 abstention, based on sufficient evidence of carcinogenicity in well-conducted animal inhalation studies, that special-purpose glass fibers with the physical characteristics as follows longer, thinner, less soluble fibers (for 1 example, > 15 μm length with a kdis of < 100 ng/cm2/h) are reasonably anticipated to be a human carcinogen for the listing status in the RoC. The major considerations discussed that led the panel to its recommendation include the observations of tumors in multiple species of animals (rats and hamsters). Both inhalation and intraperitoneal routes of exposure produced tumors, although inhalation was considered more relevant for humans.
Fiberglass insulation mold: occurrence of mold contamination in fiberglass insulation can be impossible to see with the naked eye, but can be significant
World Health Organization International Agency for Research on Cancer - IARC Monographs on the Evaluation of Carcinogenic Risks to Humans - VOL 81 Man-Made Vitreous Fibers, 2002, IARCPress, Lyon France, pi-ii-cover-isbn.qxd 06/12/02 14:15 Page i - World Health Organization, 1/21/1998. - Fiberglass insulation is an example of what IARC refers to as man made vitreous fiber - inorganic fibers made primarily from glass, rock, minerals, slag, and processed inorganic oxides. This article provides enormous detail about fiberglass and other vitreous fibers, and includes fiberglass exposure data.
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81.pdf - the article (large PDF over 6MB)
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6A.pdf - article details
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6C.pdf - studies of cancer in experimental animals in re vitreous fibers such as fiberglass;
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6E.pdf - summary of data reported & evaluation
http://monographs.iarc.fr/ENG/Monographs/vol81/mono81-6F.pdf for the article references
To search the IARC monographs on various environmental concerns and carcinogens, use http://monographs.iarc.fr/ENG/Monographs/PDFs/index.php
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How to Test Building Insulation for Mold Contamination

Question: How should we sample fiberglass insulation for mold when investigating a building?

Answer: Detailed Description of Methods for Testing Building Insulation for Mold

Air Sampling Cassettes for Insulation Mold Test

Burkard Personal Air Sampler and Prepared Slide for Insulation Mold Test

Alternative, low-cost Air Pumps for Building Insulation Mold Testing

Constructing a Clean Test Chamber to Screen Insulation for Mold

Quantitative Analysis of Insulation Samples for Mold Contamination

Should All Building Insulation be Tested for Mold?

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Fiberglass in buildings: hazards, testing, cleanup, prevention: references & products