Air change rate and concentration of formaldehyde in residential indoor air

The purpose of this study was to investigate the relationship between air change rates and indoor concentrations of formaldehyde. Concentrations of formaldehyde and air change rates were measured in 96 homes in Québec City, Canada, in winter 2005. House characteristics such as heating systems or recent renovations were also documented. Formaldehyde concentrations were regressed to air change rates among the entire sample and among some sub-samples of homes, and predictive intervals were computed. The air change rate ensuring a formaldehyde concentration below Health Canadaʹs guideline value of 50 μg m−3 in 95% of homes was 0.26 h−1 based on the entire sample, 0.34 h−1 in homes with recent off-gassing sources of formaldehyde, and 0.37 h−1 in homes heated mainly by electrical baseboard heaters. These results indicate that ventilation effectively decreases formaldehyde concentrations, but some categories of homes such as those with new off-gassing sources and homes heated by electrical baseboard heaters may require a higher air change rate to keep their formaldehyde levels within Health Canadaʹs guidelines.