Risk of childhood asthma prevalence attributable to residential proximity to major roads in Montreal, Canada

Objectives: Exposure to traffic-related air pollutants plays a role in several health outcomes. A large body of evidence tends to link asthma in children with traffic exposure. Increasing asthma prevalence and incidence in children in Canadian cities has been of concern for public health authorities. The following study focuses on estimating the risk of asthma prevalence attributable to residing in proximity to major roads on the Island of Montreal, Canada. Methods: Risk functions pertaining to asthma in children and residential proximity to major roads were selected from the literature and applied to Montreal. Asthma prevalence was taken from population-based studies. Population data were retrieved from Canadian census. Exposure was estimated using the proximity to major road and highway category of the Desktop Mapping Technologies Inc. database (DMTI Spatial Inc.). Results: Based on different studies, the percentage of prevalent asthma cases attributable to residing within 50 metres of a major road or highway for children aged 2, 4 and 6 years varied between 2.4% (0-4.3), 5.6% (0.1-8.6) and 5.9% (0.1-9.0). For the 5-7 year age group residing within 75 m of a major road or highway, the percent of cases was 6.4% (2.6-9.3). For children aged 8 to 10 residing within 75 m of a highway only, the percent of cases was 0.7% (0.2-0.9). Conclusion: These numbers represent the best crude estimates and are an indication of a possible range of cases linked to residential proximity to major roads. As there are uncertainties linked to the application of exposure-response functions, these estimates will be reassessed as new evidence is gathered through further research. Key words: Asthma; attributable risks; children; traffic; air pollutants La traduction du resume se trouve a la fin de l'article. Objectif : L'exposition aux polluants atmospheriques lies au trafic routier contribue a plusieurs resultats sanitaires. De nombreuses preuves tendent a lier l'asthme chez les enfants a l'exposition au trafic routier. La prevalence et l'incidence croissantes de l'asthme chez les enfants dans les villes du Canada preoccupent les autorites de sante publique. Nous avons estime le risque de prevalence de l'asthme imputable au fait de resider a proximite de grandes arteres sur l'ile de Montreal, au Canada. Methode : Nous avons selectionne dans la litterature scientifique et applique a Montreal les fonctions de risque afferentes a l'asthme chez les enfants et au fait d'habiter a proximite de grandes arteres. La prevalence de l'asthme vient d'une etude populationnelle. Les donnees demographiques sont extraites du Recensement du Canada. Nous avons estime l'exposition a l'aide d'une categorie de la base de donnees de Desktop Mapping Technologies Inc. (DMTI Spatial Inc.): << proximite de grandes routes et arteres >>. Resultats : D'apres differentes etudes, le pourcentage de prevalence des cas d'asthme imputable au fait de vivre a moins de 50 metres d'une grande route ou artere, pour les enfants de 2, 4 et 6 ans, variait entre 2,4% (0-4,3), 5,6% (0,1-8,6) et 5,9% (0,1-9,0). Dans le groupe des 5 a 7 ans vivant a moins de 75 m d'une grande route ou artere, le pourcentage de cas etait de 6,4% (2,6-9,3). Chez les enfants de 8 a 10 ans vivant a moins de 75 m d'une route seulement, le pourcentage de cas etait de 0,7% (0,2-0,9). Conclusion : Ces chiffres representent les meilleures estimations brutes et pourraient indiquer un eventail de cas lies au fait de resider a proximite d'une grande route. Il y a cependant des incertitudes liees a l'application des fonctions exposition-reaction; ces estimations seront donc reevaluees a mesure que les chercheurs reuniront de nouvelles preuves. Mots cles : asthme; risques attribuables; enfant; trafic routier; polluants atmospheriques
Vehicle traffic emissions result in a complex mixture of carbon monoxide (CO), nitrogen oxides (NOx), particulate matter (mainly ultra-fine particles) and air toxics (1,3-butadiene, benzene, formaldehyde, polycyclic aromatic hydrocarbons-PAHs). For [...]