A survey of typical exposures to formaldehyde in Houston area residences

A survey of indoor air quality under warm weather conditions, in a variety of Houston area residences not selected in response to occupant complaints, revealed a distribution of indoor formaldehyde concentrations ranging from less than 0.008 ppm to 0.29 ppm, with an arithmetic mean of 0.07 ppm. Approximately 15% of the monitored residences had concentrations greater than 0.10 ppm. Formaldehyde levels were observed to depend on both age of dwelling and the structural classification of the residence. These factors are not independent and reflect the influence of more fundamental variables, such as the rate of exchange of indoor and outdoor air and the overall emission potential of indoor materials. The results of this survey suggest that considerable population exposures to excess (greater than 0.10 ppm) formaldehyde concentrations may occur in the residential environment, indicating the need for improved control strategies.