The American Lung Association gives the following information on their web site "Facts About Fiberglass". "Fiberglass insulation packages display cancer warning labels. These labels are required by the U.S. Occupational Safety and Health Administration (OSHA) based on determinations made by the International Agency for Research on Cancer (IARC) and the National Toxicology Program (NTP)." (more at the American Lung Association web site) That said, this conclusion is controversial. But cancer is not the only bad thing that can happen to the occupant of the house. There are other lung diseases such as asthma and emphysema. The Illinois Dept. of Public Health states that: (persons with) "worn-out duct work lined with fiberglass in their homes or workplace may have long-term exposure to fiberglass." Here in Arizona, besides traditional air conditioning, many homes are fitted with swamp coolers. The humidity really causes rapid deterioration of the fiberboard. Additionally, I know of few home installation settings where there is periodic inspections. The only time someone sees the plenum is at long intervals when the furnace or air-conditioning is replaced. And then its hit or miss if a deterioration is even noticed or discussed with the home owner. So as far as Fiberglass duct board, if it deteriorates, it is indeed a health hazard, and usually a hidden health hazard. The lady who lived previously in my home died of emphysema, likely caused by a lethal combination of smoking and chronic exposure to fiberglass. (Compare this to Smoking plus asbestos was associated with much much higher chance of cancer than either smoking only or asbestos exposure only) When I moved in and discovered this, I had to have the entire plenum and duct work remediation done with sealer and then Fosters sealer. Thus encapsulating the loose fibers and to seal out the moisture from again disrupting the deteriorating fiber board. In my opinion, contractors who install fiberglass board duct work in homes are creating long term health hazards. And this is so unnecessary. Interestingly, I have been told that the fiberboard ducts can be constructed "inside out" so the aluminum is lining the duct work and the insulation is on the outside. This insures a metal lined duct, all of the the insulation effect, and a significant contribution of the sound deadening properties. ( I say this as a physician who has had conversations with many "lung patients" HVAC contractors on the patients behalf -- and not as one directly versed in building codes)
