Associations between ambient fine particulate matter and child respiratory infection: The role of particulate matter source composition in Dhaka, Bangladesh.

Air pollution in the form of fine particulate matter (PM) has been linked to adverse respiratory outcomes in children. However, the magnitude of this association in South Asia and sources of PM that drive adverse health effects are largely unknown. This study evaluates associations between short-term variation in ambient PM and incidence of pneumonia and upper respiratory infections among children in Dhaka, Bangladesh. We also perform an exploratory analysis of the PM source composition that is most strongly associated with health endpoints. We leveraged data from health surveillance of children less than five years of age between 2005 and 2014 in Kamalapur, Bangladesh, including daily physician-confirmed diagnoses of pneumonia and upper respiratory infection. Twice-weekly source-apportioned ambient PM measurements were obtained for the same period, and Poisson regression adjusted for time-varying covariates was used to estimate lagged associations between ambient PM and respiratory infection. We use complementary matching and stratification approaches to evaluate whether these associations vary across PM source composition. Total PM mass was associated with a modest increase in incidence of pneumonia, with a peak effect size two days after exposure (rate ratio = 1.032; 95% confidence interval = 1.008-1.056). We did not identify a significant association between PM and upper respiratory infection. Stratified and matching analyses suggested this association was stronger among days when ambient PM had a higher mass percent associated with brick kiln and fugitive lead emissions.: This study suggests that elevated ambient PM contributes to increased incidence of child pneumonia in urban Dhaka, and that this relationship varies among days with different source composition of PM.