Urban Air Pollution Assessed Using a Dispersion Model Related to Allergic and Respiratory Health in Children

Abstract

WM1-O-02 Introduction: The impact of urban air pollution (AP) on respiratory and allergic health is still debated. This might have been the result of inaccurate classification of exposure. Our cross-sectional study was intended to assess the role of AP modelled using a dispersion model in the prevalence of allergic and respiratory outcomes in children. Methods: A total of 6683 children 9 to 11 years of age recruited between March 1999 and October 2000 from 108 schools randomly selected in 6 French cities underwent a clinical examination including skin prick test to common aeroallergens to assess allergic sensitisation and the standardized protocol of the run test to assess exercise-induced bronchial reactivity (EIB). The prevalence of asthma, allergic rhinitis (AR), and eczema was determined through a standardized questionnaire, including the International Study of Asthma and Allergies in Childhood core questions, completed by the parents. Annual mean concentrations of benzene, VOC, CO, NO2, NOx, PM10, and SO2 were calculated, in front of the 108 schools attended by the children, by the validated STREET 5 software, which combines data on regional and local components of AP. STREET contains a database of emissions estimated by the IMPACT 2.0 software developed by ADEME-France and results of ambient concentrations modelled by the WinMISKAM 4.2 3D dispersion model. The input data required were background AP, traffic, and dispersion (topography and meteorology) conditions. For each air pollutant, a 2-category-exposure variable was defined with respect to the median value of the modelled concentrations at school. Statistical analyses were performed using Generalized Estimating Equations. Results: Adjusted odds ratios (OR) for EIB indicated significant positive associations with all modelled air pollutants [OR = 1.7 (95% CI, 1.3–2.1) with SO2, 1.5 (1.2–1.8) with benzene, 1.3 (1.1–1.7) with PM10], except NO2. Asthma was significantly related to benzene (1.3; 1.0–1.6), SO2 (1.3; 1.0–1.6), and PM10 (1.3; 1.0–1.6), AR to PM10 (1.2; 1.0–1.4), eczema to NO2 (1.2; 1.1–1.4) and sensitization to pollen to benzene (1.2; 1.0–1.5) and PM10 (1.4; 1.1–1.7). Positive associations of asthma with VOC and CO, of AR with benzene and SO2, of eczema with PM10, and of sensitization to pollen with VOC reached borderline statistical significance. Sensitivity analyses suggested stronger associations between sensitisation to pollen and AP in girls than in boys. Positive associations were more pronounced among long-term resident children (current address for at least 8 years). Conclusions: Accurate modelization of urban AP shows an augmented childhood prevalence of respiratory and allergic diseases in areas with high concentrations of air pollutants.