Mitigation of residential formaldehyde contamination by indoor climate control.

The effectiveness of indoor climate as a mitigation measure for indoor formaldehyde contamination was studied in a mobile home. The effects of nine indoor climate regimes on formaldehyde levels were evaluated for the temperature and humidity ranges of 20 degrees C to 30 degrees C and 30% RH to 70% RH. Formaldehyde levels at the lowest combination of temperature and relative humidity (20 degrees C, 30% RH) were only 20% of those measured at the highest combination of temperature and relative humidity (30 degrees C, 70% RH) evaluated. Reducing temperature alone (from 30 degrees C to 20 degrees C) was shown to result in an approximate 70% reduction in formaldehyde levels. Reducing relative humidity alone (from 70% to 30%) resulted in an approximate 40% reduction in formaldehyde levels. A high linear correlation was observed between formaldehyde levels and temperature and between formaldehyde levels and relative humidity. Analysis of energy consumption and associated costs indicated that temperature reduction from 25 degrees C to 20 degrees C during the cooling season would increase energy usage costs by about 20%; temperature reduction in the heating season would result in both reduced formaldehyde levels and reduced energy costs. Although effective, humidity control--particularly to 30% under summertime conditions--appears to be prohibitively costly. The relationship between temperature and formaldehyde levels suggests that climate control also may be appropriate for reducing indoor levels of other continuously generated contaminants.