Trafficrelated air pollution near busy roads

Recent studies, primarily in Europe, have reported associations be-tween respiratory symptoms and residential proximity to traffic; however, few have measured traffic pollutants or provided informa-tion about local air quality. We conducted a school-based, cross-sectional study in the San Francisco Bay Area in 2001. Information on current bronchitis symptoms and asthma, home environment, and demographics was obtained by parental questionnaire (n 1,109). Concentrations of traffic pollutants (particulate matter, black car-bon, total nitrogen oxides [NOX], and nitrogen dioxide [NO2]) were measured at 10 school sites during several seasons. Although pollut-ant concentrations were relatively low, we observed differences in concentrations between schools nearby versus those more distant (or upwind) from major roads. Using a two-stage multiple-logistic regression model, we found associations between respiratory symp-toms and traffic-related pollutants. Among those living at their current residence for at least 1 year, the adjusted odds ratio for asthma in relationship to an interquartile difference in NOX was 1.07 (95 % confidence interval, 1.00–1.14). Thus, we found spatial variability in traffic pollutants and associated differences in respira-tory symptoms in a region with good air quality. Our findings sup-port the hypothesis that traffic-related pollution is associated with respiratory symptoms in children