Characterization of traffic-related air pollutant metrics at four schools in El Paso, Texas, USA: Implications for exposure assessment and siting schools in urban areas

• Published in: Atmospheric environment (1994) 2013-12, Vol.80, p.140-151
• Main Authors: Raysoni, Amit U., Stock, Thomas H., Sarnat, Jeremy A., Montoya Sosa, Teresa, Ebelt Sarnat, Stefanie, Holguin, Fernando, Greenwald, Roby, Johnson, Brent, Li, Wen-Whai
• Format: Article
• Language: English
• Subjects: Air. Soil. Water. Waste. Feeding; Applied sciences; Atmospheric pollution; Biological and medical sciences; Black carbon; BTEX; Combustion and energy production; Environment. Living conditions; Exact sciences and technology; Indoor pollution and occupational exposure; Medical sciences; Nitrogen dioxide; Particulate matter; Pollution; Pollution sources. Measurement results; Public health. Hygiene; Public health. Hygiene-occupational medicine; School siting; US–Mexico border
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2013.07.056

Children spend substantial amount of time within school microenvironments; therefore, assessing school-based exposures is essential for characterizing and preventing children's health risks to air pollutants. Indeed, the importance of characterizing children's exposures in schools is recognized by the US Environmental Protection Agency's recent initiative to promote outdoor air monitoring networks near schools. As part of a health effects study investigating the impact of traffic-related air pollution on asthmatic children along the US–Mexico border, this research examines children's exposures to, and spatio-temporal heterogeneity in concentrations of, traffic-related air pollutants at four elementary schools in El Paso, Texas. Three schools were located in an area of high traffic density and one school in an area of low traffic density. Paired indoor and outdoor concentrations of 48-h fine and coarse particulate matter (PM2.5 and PM10–2.5), 48-h black carbon (BC), 96-h nitrogen dioxide (NO2), and 96-h volatile organic compounds (VOCs) were measured for 13 weeks at each school. Outdoor concentrations of PM, NO2, BC, and BTEX (benzene, toluene, ethylbenzene, m,p-xylene, o-xylene) compounds were similar among the three schools in the high-traffic zone in contrast to the school in the low-traffic zone. Results from this study and previous studies in this region corroborate the fact that PM pollution in El Paso is dominated by coarse PM (PM10–2.5) and fine fraction (PM2.5) accounts for only 25–30% of the total PM mass in PM10. BTEX species and BC are better surrogates for traffic air pollution in this region. Correlation analyses indicate a range of association between indoor and outdoor pollutant concentrations due to uncontrollable factors like student foot traffic and varying building and ventilation configurations across the four schools. Results suggest the need of micro-scale monitoring for children's exposure assessment, which may not be adequately characterized by the measurements from a centralized monitoring site. •Study characterizing traffic air pollutants at four schools in El Paso, Texas, USA.•Paired indoor–outdoor sampling of PM2.5, PM10–2.5, BC, VOCs and NO2 for 13 weeks.•Three schools in high traffic exposure zones and one in low traffic exposure zone.•Spatially resolved traffic environmental indicators used in various exposure settings.•Substantial intra-urban spatio-temporal heterogeneity in pollutant concentrations observed.