Ambient air pollution and the risk of pediatric-onset inflammatory bowel disease: A population-based cohort study

Background: High-income nations have the highest rates of inflammatory bowel disease (IBD). The incidence of pediatric-onset IBD is increasing faster than IBD diagnosed in older individuals. Previous epidemiological studies have shown that air pollution might be a risk factor for development of earlier-onset IBD, but results remain mixed. Objectives: The objective of this study was to evaluate the associations between maternal and early-life exposures to nitrogen dioxide (NO2), fine particulate matter (PM2.5), ozone (O3,) and oxidant capacity (Ox) and risk of pediatric-onset IBD diagnosis. Methods: We conducted a retrospective cohort study using linked population-based health administrative data. Singleton livebirths in Ontario, Canada between April 1st, 1991 and March 31st, 2014 were included. We investigated the association between weekly exposures during pregnancy and annual exposures from birth until the age of 18 years, and IBD diagnosed