From the aEnvironmental and Occupational Health, Public Health Ontario, Toronto, ON, Canada; bPrimary Care and Populational Health Research Program, Institute for Clinical Evaluative Sciences, Toronto, ON, Canada; cOccupational and Environmental Health Division, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; dDepartment of Civil Engineering, McGill University, Montreal, QC, Canada; eDepartment of Environmental Health Sciences, Fielding School of Public Health, University of California, Los Angeles, CA; fClinical Public Health Division and Epidemiology Division, Population Studies Division, Health Canada, Ottawa, ON, Canada; gPopulation Studies Division, Health Canada, Ottawa, ON, Canada; hDepartment of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada; iAtomic and Molecular Physics Division, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA; jAir Health Science Division, Health Canada, Ottawa, ON, Canada; and kDepartment of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, QC, Canada.
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Background:Previous studies reported that long-term exposure to traffic-related air pollution may increase the incidence of hypertension and diabetes. However, little is known about the associations of ultrafine particles (≤0.1 μm in diameter) with these two conditions.Methods:We conducted a population-based cohort study to investigate the associations between exposures to ultrafine particles and nitrogen dioxide (NO2) and the incidence of diabetes and hypertension. Our study population included all Canadian-born residents aged 30 to 100 years who lived in the City of Toronto, Canada, from 1996 to 2012. Outcomes were ascertained using validated province-wide databases. We estimated annual concentrations of ultrafine particles and NO2 using land-use regression models and assigned these estimates to participants’ annual postal code addresses during the follow-up period. Using random-effects Cox proportional hazards models, we calculated hazard ratios (HRs) and 95% confidence intervals (CIs) for ultrafine particles and NO2, adjusted for individual- and neighborhood-level covariates. We considered both single- and multipollutant models.Results:Each interquartile change in exposure to ultrafine particles was associated with increased risk of incident hypertension (HR = 1.03; 95% CI = 1.02, 1.04) and diabetes (HR = 1.06; 95% CI = 1.05, 1.08) after adjusting for all covariates. These results remained unaltered with further control for fine particulate matter (≤2.5 μm; PM2.5) and NO2. Similarly, NO2 was positively associated with incident diabetes (HR = 1.06; 95% CI = 1.05, 1.07) after controlling for ultrafine particles and PM2.5.Conclusions:Exposure to traffic-related air pollution including ultrafine particles and NO2 may increase the risk for incident hypertension and diabetes. See video abstract at, http://links.lww.com/EDE/B337.