| Summary: | Otitis media is the leading reason children visit their doctor or consume antibiotics. It has been postulated that ambient air pollution is a risk factor for otitis, based on the known association with environmental tobacco smoke and a number of recent studies. This research utilized administrative data to identify and follow a population-based birth cohort of 59,917 children, born during 1999-2000 in southwestern British Columbia. The incidence and recurrence of otitis media was characterized during the first three years of life and available information on risk factors were assessed. Air pollution exposures (CO, NO, NO₂, O₃, PM₂.₅, PM₁₀, SO₂, black carbon, woodsmoke, point source and road proximity) were estimated for the first 24 months of life using ambient monitoring data, temporally adjusted land use regression models and proximity measures; and assigned to children based on residential postal code. The relationship between physician visits for otitis media and 2-month average pollutant exposures was assessed longitudinally. Finally, the economic burden of otitis media attributable to air pollution was calculated using data from the universal healthcare system and estimates from the literature. Otitis media incidence was relatively low (42% at 2years; 49% at 3years) compared with previous studies and peaked in the winter and at 8-10 months of age. Male gender, First Nations status and low socio-economic status were identified as strong risk factors for otitis media in this population. In analyses that included air pollution, CO, NO, NO₂ and woodsmoke were independent risk factors before seasonal adjustment; and NO, PM₂.₅ and woodsmoke were independent risk factors after seasonal adjustment. For this population, the cost of otitis media attributable to woodsmoke was valued at (2003) $420,464. Associations were found between otitis media and some air pollutants in a large birth cohort with relatively low ambient air pollution exposure. Null or protective associations (SO₂, O₃, black carbon) may be partially explained by temporal and spatial correlations between pollutants and otitis media. If the associations observed in this study are causal, the substantial economic burden attributable to air pollution suggests that it be considered a modifiable risk factor for this important childhood disease.
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