For The IAQ Industry Feb, 2008 Vol. 1

Interesting Study

Studies from around the world have shown a consistently strong correlation between occupant reported respiratory disease symptoms and reported moisture and mold problem in houses. One Canadian study on the subject involved 402 houses and produced interesting results.

1) Air leaky houses did not have less mold than tight ones
2) Tighter houses had lower air exchange rates, but did not have higher relative humidities
3) Leaky houses had higher predicted and measured air exchange rates and lower relative humidities
4) Leaky houses did not guarantee good ventilation in bedrooms
5) Visible mold growth did not correlate well with other measurements of mold contamination in air or dust
6) Local moisture sources and problem were a better predictor of visible mold growth than relative humidity
7) Mold growth from condensation on windows was common, even in houses with low measured mold in air and dust
8) Many of the sources of moisture problems were not related to condensation, but were caused by bathroom splashing and wetting; basement water leaks; wet refrigerator defrost or drain pans, etc.
9) A disproportionate number of the highly-contaminated houses were built in the 1970s while a disproportionate number of the low-exposure houses were built since 1986
10) Ventilation by itself will not prevent problems. It is source rates that dominate the existence of problems, since ventilation varies slightly compared to the large variation in source rates.

Don't Forget
The EPA says that use of sanitizers and disinfectant products in HVAC systems could lead to significant exposures in indoor environments with potentially unreasonable adverse effects. The EPA further explains that even though a product may be permitted for use on hard, non-porous surfaces, its directions for use may not specifically include the use of the product in HVAC&R systems. The EPA has not assessed the potential for such products to affect occupant health when used in HVAC system cleaning, nor has the agency tested product efficacy for that application.

Are You a Contributor?
Research showed that humans make a major contribution to indoor air pollution in offices - their freshly dry-cleaned clothes emit dry cleaning solvents such as trichlorethane and perchlorethane. Scent molecules and other toiletrie chemicals emit gas such as limonene, terpinene, camphene, alpha-pinene and anything up to 100 other chemicals used in perfumes. Plus, our bodies produce acetone and isoprene naturally which also becomes part of the chemical soup.

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