['The purpose of this study was to explore novel multipollutant exposure assessments using the Air Quality Health Index in relation to emergency department visits for otitis media (OM).', 'This study was a retrospective analysis using information from emergency department visits for OM, air pollution, and weather databases.', 'For children 3 years of age or younger, there were 4,815 emergency department visits for OM over a 6-year period across hospitals in Windsor, Ontario, Canada. Both time-stratified case-crossover and nonlinear time series distributed lag analyses were applied to investigate the association between the Air Quality Health Index and visits for OM.', 'Using case-crossover analysis, there was an increase in emergency department visits with OM diagnoses 6 to 7 days postexposure to increased ozone and 3 to 4 days after exposure to increased particulate matter. For every 1 unit increase in the Air Quality Health Index, discharge diagnosis of OM increased 5% to 6% three days postexposure. Effects were stronger using the nonlinear time series analysis. The overall risk for OM, in the first 15 days after an increase in the Air Quality Health Index, was 1.22 times the risk of OM on days following no increase in exposures.'] Does the Air Quality Health Index and Emergency Department visit for Otitis Media?