Childhood Incident Asthma and Traffic-Related Air Pollution at Home and School.

Environ Health Perspect. 2010 Mar 22. [Epub ahead of print]

Childhood Incident Asthma and Traffic-Related Air Pollution at Home and School.

McConnell R, Islam T, Shankardass K, Jerrett M, Lurmann F, Gilliland F, Gauderman J, Avol E, Kuenzli N, Yao L, Peters J, Berhane K.

University of Southern California School of Medicine.

Abstract

Background: Traffic-related air pollution has been associated with adverse cardio-respiratory effects, including increased asthma prevalence. However, there has been little study of effects of traffic exposure at school on new onset asthma. Objectives: To evaluate the relationship of new onset asthma with traffic-related pollution near homes and schools. Methods: Parent-reported physician diagnosis of new onset asthma (N=120) was identified during three years of follow-up of a cohort of 2497 kindergarten and first grade children who were asthma- and wheezing-free at study entry into the southern California Children's Health Study. Traffic-related pollution exposure was assessed based on a line source dispersion model of traffic volume, distance from home and school, and local meteorology. Regional ambient ozone, nitrogen dioxide (NO2), and particulate matter were measured continuously at one central site monitor in each of 13 study communities. Hazard ratios (HRs) for new onset asthma were scaled to the range of ambient central site pollutants and to the residential inter-quartile range for each traffic exposure metric. Results: Asthma risk increased with modeled traffic-related pollution exposure from roadways near homes (HR 1.51; 95% confidence interval 1.25-1.82) and near schools (HR 1.45;1.06-1.98). Ambient NO2 measured at a central site in each community was also associated with increased risk (HR 2.18;1.18-4.01). In models with both NO2 and modeled traffic exposures, there were independent associations of asthma with traffic-related pollution at school and home, while the estimate for NO2 was attenuated (HR 1.37;0.69,2.71). Conclusions: Traffic-related pollution exposure at school and homes may both contribute to the development of asthma.