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Open AccessArticle

Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants

Department of Environmental and Occupational Health, School of Public Health, University of Montreal, Montréal, QC H2L 1M3, Canada
Direction Régionale de Santé Publique du CIUSSS Centre-Sud-de-l’Île-de-Montréalde Montréal, Montréal, QC H2L 1M3, Canada
Institut Natonal de la Santé Publique du Québec, Québec, QC H2L 1M3, Canada
Department of Medicine, Laval University, Québec, QC H2L 1M3, Canada
British Columbia Centre for Disease Control, Vancouver, BC V5Z 4R4, Canada
Université de Montréal Public Health Research Institute, Montreal, QC H2L 1M3, Canada
Author to whom correspondence should be addressed.
Academic Editor: Paul B. Tchounwou
Int. J. Environ. Res. Public Health 2016, 13(8), 771;
Received: 9 May 2016 / Revised: 5 July 2016 / Accepted: 8 July 2016 / Published: 1 August 2016
Background: It is well established that short-term exposure to ambient air pollutants can exacerbate asthma, the role of early life or long-term exposure is less clear. We assessed the association between severe asthma exacerbations with both birth and annual exposure to outdoor air pollutants with a population-based cohort of asthmatic children in the province of Quebec (Canada). Method: Exacerbations of asthma occurring between 1 April 1996 and 31 March 2011 were defined as one hospitalization or emergency room visit with a diagnosis of asthma for children (<13 years old) already diagnosed with asthma. Annual daily average concentrations of ozone (O3) and nitrogen dioxide (NO2) were estimated at the child’s residential postal code. Satellite based levels of fine particulate (PM2.5) estimated for a grid of 10 km by 10 km were also assigned to postal codes of residence for the whole province. Hazard ratios (HRs) were estimated from Cox models with a gap time approach for both birth and time-dependant exposure. Results: Of the 162,752 asthmatic children followed (1,020,280 person-years), 35,229 had at least one asthma exacerbation. The HRs stratified by age groups and adjusted for the year of birth, the ordinal number of exacerbations, sex, as well as material and social deprivation, showed an interquartile range increase in the time-dependant exposure to NO2 (4.95 ppb), O3 (3.85 ppb), and PM2.5 (1.82 μg/m3) of 1.095 (95% CI 1.058–1.131), 1.052 (95% CI 1.037–1.066) and 1.025 (95% CI 1.017–1.031), respectively. While a positive association was found to PM2.5, no associations were found between exposure at birth to NO2 or O3. Conclusions: Our results support the conclusion, within the limitation of this study, that asthma exacerbations in asthmatic children are mainly associated with time dependent residential exposures less with exposure at birth. View Full-Text
Keywords: asthma; air pollution; childhood; exacerbation asthma; air pollution; childhood; exacerbation
MDPI and ACS Style

Tétreault, L.-F.; Doucet, M.; Gamache, P.; Fournier, M.; Brand, A.; Kosatsky, T.; Smargiassi, A. Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants. Int. J. Environ. Res. Public Health 2016, 13, 771.

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