Associations between prenatal exposure to air pollutants and Autism Spectrum Disorder: A population-based cohort study in Metro Vancouver, Canada

The etiology of autism spectrum disorder (ASD) is poorly understood, but emerging evidence suggests that environmental factors may have a larger contributing role to the risk of ASD than previously thought. Recent studies suggest an association between air pollution and ASD. We conducted a retrospective, population-based cohort study of nearly all births in Metro Vancouver, Canada, from 2004–2009 to evaluate prenatal exposures to PM2.5, NO, and NO2 as modifiable environmental risk factors for ASD. Children were diagnosed with ASD using a standardized assessment of Autism Diagnostic Interview-Revised and Autism Diagnostic Observation Schedule. Using temporally adjusted land use regression models, we estimated monthly mean ambient air pollution exposures during pregnancy for each person at their home address. We observed positive associations between air pollutant exposures and increased risk of ASD, especially for males, in a population-based cohort living in an area with relatively low levels of air pollution.