Nitrogen dioxide inside and outside 137 homes and implications for ambient air quality standards and health effects research

Integrated nitrogen dioxide measurements were taken by diffusion tube samplers inside and outside 137 homes in Portage, WI, over a one-year period. The annual mean ambient no 2 concentrations were 10-15 mg/m3. No 2 levels inside the kitchens of 112 homes with gas stoves averaged 50 mg/m3 higher, and bedroom levels were about 30 mg/m3 higher, than outdoor levels. Ten percent of gas cooking homes had annual average kitchen no 2 levels higher than the natl ambient air Quality standard of 100 mg/m3. No 2 levels inside the kitchens of 25 homes with electric stoves were two-thirds outdooor levels, and bedroom levels were one-half outdoor levels. The variation of no 2 levels among homes due to differences in stove use, emission rates, and air exchange rates impedes the development of prediction models.