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Airborne particle size effects on air quality testing: this document provides information about the role of particle size and lab procedures in the detection of small particles of fiberglass fragments and indoor air quality fiberglass contamination issues in residential and light-commercial buildings. This article describes risks of inaccuracies in airborne fiberglass and similar particle studies if the forensic analyst fails to use procedures that can detect very small particles & fragments.
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Experienced forensic microscopists will almost certainly agree that it is very common to find fiberglass insulation fragments in indoor dust and air samples. Most often analysts recognize and identify large fiber particles - lengths considerably longer than other indoor dust analytes such as mold or pollen.
These comparatively large fiberglass particles are typicallyi low enough in frequency and large enough in size that experts will agree that they are unlikely to pose a health risk to building occupants. Indeed manufacturer MSDS sheets indicate that "There are no known health effects from the long term use or contact with nonrespirable continuous filament fibers. As manufactured, PPG glass fibers are nonrespirable. Nonrespirable fibers cannot reach the deep lung because they have a diameter of greater than 3.5 micrometers."
But what about the level of ultra-small [and respirable] fiberglass fragments that might be present in some buildings where insulation has been tramped-on, stomped about, or otherwise damaged and abused? It would appear that "if you don't look for it, you won't find it and you won't report it" is a common problem with certain particles that may be present but not tested-for.
About these small fiberglass fragments, one manufacturer explains:
And we agree that in proper and normal installations that assumption sounds very reasonable. But having inspected several thousand buildings, we have certainly encountered conditions in which insulation has been installed or damaged in a manner risking an increased level of these small fragments.
DJF Opinion: we frequently find fiberglass fragments in indoor air samples, particularly where fiberglass HVAC duct material are in a building and where fiberglass insulation has been left exposed in a living or occupied area (such as in the ceiling above an unfinished basement being used as an office or family play area). If someone has attempted to mechanically "clean" HVAC duct work which was lined with fiberglass insulation, it is likely that I'll find a higher presence of fiberglass fragments in indoor air and in settled dust.
We continue to collect field data as well as occupant complaints in buildings for research purposes. To date our field data suggest that there is more fiberglass in residential building air than is recognized. The skin, eye, and respiratory irritant effects of exposure to fiberglass dust and particles has been widely acknowledged and appears, for example, in the MSDS for various fiberglass products. 
But in our opinion a there is a growing level of concern regarding these fibers, in particular where ultra-small fragments are present.
DJF Opinion: Frequent presence of fiberglass fragments in air and some dust samples, suggests that an HVAC duct system or exposed fiberglass insulation in the building may be contributing unwanted and potentially unsafe levels of these fibers.
What may be the sources of these fiberglass fragments? Here are some examples:
While the fiberglass industry does not necessarily agree these particles in homes constitute a hazard, independent studies and warnings at US government health-related websites suggest that there may be carcinogenic or respiratory health hazards from exposure to high levels of fiberglass particles in some buildings and/or work environments.
The health risk of small airborne fiberglass particles is likely to depend on the level in the building, the exposure level of the occupants, and other factors.
If we find frequent presence of fiberglass fibers in air or interior dust samples further investigation, cleaning, and particularly investigation of air handling equipment and duct systems in the building would be appropriate.
If fiberglass HVAC duct work has been installed I very often find significant fiberglass levels in interior air and dust samples.
Because these materials cannot be mechanically cleaned and because I do not recommend encapsulant sprays, replacement could be in order.
We would not expect and do not usually find evidence of movement of significant levels of fiberglass fragments from insulated attics, nor from enclosed (finished) walls, ceilings into living areas under normal conditions.
It is possible that small fiberglass particles in air may constitute a meaningful health risk (obviously depending on the overall exposure level) which has not been explored.
We suggest that that prudent avoidance would be appropriate. Improper cleaning or treatment of fiberglass ducts with biocides may in fact increase rather than decrease indoor air quality problems in a building, particularly if occupants have other respiratory or pulmonary concerns/vulnerabilities.
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Frequently Asked Questions (FAQs)
I am preparing to install a HVAC system in my home which has no duct work. One of the contractors wants to use fiberglass duct system. I had already been told by a local energy check business that this would not be wise. Your article has confirmed that advice. Thank you. - Fiona
Fiberglass ductwork could be fine for HVAC application provided that it is foil-covered on all sides. What is impossible to clean is ductwork that leaves fiberglass exposed on the duct interior.
Question: where are details about testing & lab procedures for finding fiberglass in building air & dust?
Your headline suggested ways to detect fiberglass particles but the article never touches on it. I'd like to know how to test for it. - Bubba
Reply: also see Lab Identification of Fiberglas
Bubba, your note was helpful and we've clarified the text in several related fiberglass and dust articles. The article above focuses on the role of particle size in the detection of fiberglass in air and dust samples as well as in hazard research.
Question: We see fiberglass in our HVAC ducts and we get itchy
we live in a mobile (manufactured home) 1991 it was built. and we have fiberglass ductwork. You can see the fiberglass when you look into the floor vents. At times we get very itchy and so do our guests. When you look there is nothing you can see on our skin. Could our fiberglass be breaking down? Also, many of out guests expericence allergy symptoms when they come over. Any Ideas?? - Laura Dunne 5/1/2012
Laura, I haven't found significant fiberglass fiber release from fiberglass ductwork in buildings except in cases where some fool tried to clean the fiberglass-lined ducts mechanically. Mechanical cleaning or even aggressive brushing and vacuuming can damage the bonded surface of the ducts.
For completeness, also see MORGELLONS SYNDROME.
Reader Comment: consider HVAC duct coatings to seal exposed fiberglass
My question to you is whether you have looked at coatings, such as http://www.fiberlock.com/mold/hvac.html to seal the fibers in place? Of course, as duct cleaner, we always recommend replacing fiberglass liner with a closed cell product like http://www.armacell.com/WWW/armacell/INETArmacell.nsf/ tandard/D489E388CFD3159EC12576D20065B99E? OpenDocument&Nav= 4111A0A8CA88966C8025774C005B9CCE.
However, when replacement is impossible or impractical, applying sealants/coatings to fiberglass duct board and duct liner is a valid alternative (especially in double-walled perforated duct). I don’t believe there are any cleaning methods that can always prevent damage or further deterioration to even new liner. Regardless, wouldn’t you agree that coating/sealing is better than nothing? Actually, I think the use of fiberglass in HVAC systems should be stopped. Thanks for your great website, by the way.
Thanks for the discussion Ms Gallagher. We particularly appreciate comments or critique from readers who have expertise in the topic being discussed.
Indeed, I have considered duct coating coating products, have seen some applications of coatings as a "remedy" for damaged HVAC duct interiors and for interior surfaces that are soft, cannot be cleaned, and are contaminated with mold, allergens, even pathogens.
In general I agree with your position that for some cases a coating shoudl be considered, although it's a not completely reliable band-aid approach to a duct problem, a coating may be cost effective or may be suitable as a temporary measure pending a more costly duct replacement.
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