Long-Term Exposure to Industrial Air Pollution Emissions and the Incidence of Childhood Asthma: The Use of a Population-Based Birth Cohort and Dispersion Modeling

摘要

Studies on the effects of ambient air pollution have mostly focused on road traffic emissions and have mainly been performed in urban areas. We assessed the association between exposure to ambient concentrations of fine particles (PM2.5) and sulfur dioxide (SO2) resulting from industrial emissions and asthma onset in children of the province of Quebec, Canada. We used a population-based birth cohort developed from administrative health databases that comprised all children born in Quebec between March 2002 and March 2011. Using industrial emissions reported to the National Pollutant Release Inventory and hourly meteorology, we modelled yearly ambient SO2 and PM2.5 concentrations with the dispersion model CALPUFF at a fine spatio-temporal scale. Separately for each pollutant, we assessed associations between modelled yearly concentrations of PM2.5 and SO2 at the residence of children and the onset of asthma using Cox model with age as the timescale, adjusted for sex, calendar year and Pampalon's material and social deprivation index. The cohort includes 722,667 children of whom 66, 559 developed asthma between 2002 and 2011. Preliminary analyses using yearly exposure estimates from 2009-2010 and including 18,392 incident cases of asthma showed positive association for both air pollutants. For an increase equal to the median of SO2 and PM2.5 levels, mean percentage changes in the risk of asthma onset was 5.7% (95%CI: 5.2, 6.2%) and 1.6% (95%CI: 1.2, 2.1%), respectively. However, departure from linearity was noted toward the highest levels of exposure. Future work will include additional years of exposure and indirect adjustment for secondhand smoke exposure. The independence of effects of industrial emissions from those of regional background pollutant levels also deserves further consideration. Acknowledgments: This work was supported by a contract with Health Canada.