A symptom stratified, geographic cluster sample of 117 middleclass households was studied. Symptom daily diaries were obtained for 211 subjects for 2 years. Indoor sampling in 41 house was for O3, TSP, RSP, CO, temperature (T), and relative humidity (RH). Questionnaires determined type of stove and smokers in all households. Ambient pollutants (O3, TSP, CO, NO2), were monitored in or near the clusters, as was T, RH. Smoking in the household was significantly correlated with TSP and RSP. Indoor CO significantly correlated with gas stove usage, but not with outdoor CO. Children's Vmax was associated only with outdoor factors. Asthmatic Vmax was associated with smoking, gas stove use, NO2, and occasionally O3, T, and RH.