The Effects Of Prenatal And Postnatal Traffic-Related Air Pollution On The Susceptibility Of Childhood Asthma

Abstract

Objective: The aim of this study was to examine the role of exposure to traffic-related air pollution (TAP) in altering the susceptibility to asthma in children with past episodes of bronchiolitis. Methods: Lifetime wheezing, past episodes of bronchiolitis, and doctor-diagnosed asthma were evaluated by an International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire, and allergy evaluations (lung function tests and a methacholine challenge test) were conducted on 1,994 children who participated in a prospective 2-year follow-up survey. Residential exposure was assessed by proximity to a main road and the length of road, and by modeling exposure to TAP using a geographic information system. Results: The past episodes of bronchiolitis were associated with wheezing and doctor diagnosed asthma in a baseline and a follow-up study. When those who have experienced episodes of bronchiolitis were living within 75m of a major road, the risk of bronchial hyper-reactivity was associated with TAP (adjusted OR = 2.61, 95% CI 1.13-6.02) at enrollment, and the newly diagnosed asthma had significantly increased (adjusted OR = 4.62, 95% CI 1.26-16.93) by the follow-up study. Conclusions: We found an association between residential TAP exposure and asthma among children with past episodes of bronchiolitis. These results indicate that interaction of TAP and bronchiolitis may be an important factor in asthma pathogenesis in children.