Indoor-outdoor relationships of respirable sulfates and particles.

Indoor and outdoor concentrations of respirable particulates and sulfates have been measured in 68 homes in six cities for at least 1 yr. A conservation of mass model was derived describing indoor concentrations in terms of outdoor concentrations, infiltration and indoor sources. The measured data were analysed to identify important building characteristics and to quantify their effect. The mean infiltration rate of outdoor fine particulates was found to be approximately 70 %- Cigarette smqking was found to be the dominant indoor source of respirable particulates. Increased indoor concentrations of sulfates were found to be associated with smoking and also with gas stoves. The effect of full air conditioning of the building was to reduce infiltration of outdoor fine particulates by about one half, while preventing dilution and purging of internally generated pollutants. The model for indoor respirable particulate and sulfate levels was found to compare well with measurements.