Abstract
Objectives
The city of Windsor is recognized to have poor air quality in comparison with other Canadian cities. However, relatively few studies have evaluated associations between day-to-day fluctuations in air pollution levels and respiratory health in Windsor. In this study, we examined associations between short-term changes in ambient air pollution and emergency department (ED) visits for asthma in Windsor.
Methods
A time-stratified case-crossover design was applied to 3,728 ED visits for asthma that occurred in Windsor area hospitals between 2002 and 2009. Daily air pollution levels for the region were estimated using Environment Canada’s network of fixed-site monitors. ED visits were identified through the National Ambulatory Care Reporting System (NACRS). Odds ratios and their corresponding 95% confidence intervals were estimated using conditional logistic regression, and were adjusted for the confounding influence of daily number of influenza ED visits and weather variables using natural spline functions.
Results
Statistically significant associations were observed between ambient air pollution levels and ED visits for asthma in Windsor. Effects were particularly pronounced among children 2 to 14 years of age between April and September. Namely, increases in the interquartile range with 1-day lagged exposure to SO2, NO2 and CO levels were associated with increased risks of an asthma visit of 19%, 25% and 36%, respectively.
Conclusion
Exposure in Windsor to ambient air pollution increases the risk of ED visits for asthma, particularly among children.
Keywords: Air pollution, asthma, child, risk, cross-over studies
Résumé
Objectifs
La ville de Windsor est reconnue pour avoir une qualité d’air inférieure comparativement à d’autres villes canadiennes. Toutefois, peu d’études ont évalué l’association entre des fluctuations quotidiennes dans les niveaux de polluants atmosphériques et des problèmes respiratoires à Windsor. Le but de cette étude est d’évaluer l’association entre le changement à court terme de polluants atmosphériques et les admissions à l’urgence dans la ville de Windsor.
Méthode
Un devis d’étude cas-témoins de croisement stratifié sur le temps a été appliqué à 3 728 visites dans les départements d’urgence des hôpitaux de la ville de Windsor entre 2002 et 2009. Les niveaux de polluants atmosphériques pour cette région ont été estimés en utilisant les sites de surveillance de la pollution atmosphérique d’Environnement Canada. Les visites à l’urgence ont été identifiées avec le Système national d’information sur les soins ambulatoires (SNISA). Des rapports de cote (RC) accompagnés d’intervalle de confiance à 95% ont été générés en utilisant la régression logistique conditionnelle et ont été ajustés pour les facteurs confondants d’admissions quotidiennes à l’urgence pour un diagnostique d’influenza et des variables climatiques en utilisant des fonctions splines naturelles.
Résultats
Des associations statistiquement significatives ont été observés entre les polluants atmosphériques et les admissions à l’urgence pour de l’asthme à Windsor. Les effets étaient particulièrement prononcés chez les enfants de 2 à 14 ans entre les mois d’avril et septembre. Spécifiquement, une augmentation dans l’écart interquartile avec un décalage d’une journée dans l’exposition au SO2, NO2 et CO augmentait le risque d’une visite à l’urgence pour de l’asthme de 19%, 25% et 36%, respectivement.
Conclusion
L’exposition à la pollution de l’air ambiante à Windsor augmente le risque d’admission à l’urgence pour de l’asthme, particulièrement chez les enfants.
Mots clés: pollution de l’air, asthme, enfant, risque, cas-témoins de croisement
Footnotes
Conflict of Interest: None to declare.
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