Multivariate analysis of the effect of indoor fine PM on asthma morbidity. Incidence rate ratios are displayed as point estimates and 95% confidence intervals for the effect of indoor PM2.5 on asthma symptom outcomes and rescue medication use. Models were adjusted for age, race, gender, parent education, season, indoor PM2.5–10, outdoor PM2.5, and outdoor PM2.5–10. There was an increase in the incidence of asthma morbidity outcomes for every 10μg/m3 increase in PM2.5 for most symptom outcomes and for rescue medication use among both non-atopic and atopic children.