Disparate air quality impacts from roadway emissions on schools in Santa Clara County (CA)

Abstract

Vehicle emissions are major sources of air pollution linked to negative health outcomes in children. Consequently, California State Bill 352 stipulates that new schools may not be sited within 500 ft of major roadways. However, the exposure of existing schools to roadway emissions and the uneven distribution of the burden of air pollution have not been systematically explored for most cities. IN response, the objectives of our study were twofold: We used spatial analysis and an evaluation of traffic count data to develop a proximity-based approach to assessing school exposure to roadway air pollution emissions. Second, we applied our method to ask whether the risk of exposure to high concentrations of roadway emissions is equally distributed for schools in Santa Clara County (SCC; USA), and which demographic or spatial patterns emerge. In the process, our proximity-based approach estimated total annual traffic counts throughout SCC, identified major roadways, and assessed cumulative emission burdens and socio-economic indicators for each school in the study area. Results were compared to output from a physically-based model and to county asthma data. Our results suggest that (i) 14% of schools in SCC are potentially exposed to high levels of air pollution from roadways, a rate that is higher than the national average, and (ii) students from economically disadvantaged backgrounds and receiving aid are more likely to be educated in schools with higher risk of exposure to elevated levels of roadway vehicle emissions. Asthma hospitalization rates are highest in socio-economically disadvantaged areas with a higher density of major roadways. Areas of higher vehicle emissions determined by the physically-based model are in general agreement with those of the distance-based approach. We propose a combination of short- and long-term mitigation strategies to reduce the risk of exposure to vehicle emissions for school children.