Traffic-related Air Pollution and Childrenʼs Respiratory Health: Beyond Proximity to Major Roadways

Abstract

P-652 Introduction: Previous studies of the respiratory health impact of mobile source air pollutants on children have relied heavily on simple exposure metrics such as proximity to roadways and traffic density near the home or school. Few studies have conducted area-wide monitoring of indicator pollutants coupled with land-use regression modeling for exposure assessment. Based largely on proximity studies, the State of California (U.S.) has restricted the location of new schools within 500ft (168m) from a roadway averaging 50,000 or more vehicles per day (>50k-vpd) in rural and >100k-vpd in urban areas. We examined adverse effects of mobile source emissions among children living outside California's buffer area using both simple exposure metrics and a land-use regression modeling approach. Methods: The El Paso Children's Health Study was a cross-sectional study of children enrolled in the fourth and fifth grades of public elementary schools in El Paso, Texas. Measurements of nitrogen dioxide were made at 22 elementary schools. Ambient NO2 concentration, an indicator of mobile source emissions, was estimated at each child's residence using a land-use regression model. For this analysis, we restricted the cohort to 62% of the children (n=2546) who lived outside the Rio Grand River valley (above 1700m). None of these children lived within 200m of a roadway with >90k-vpd; nly 3.2% lived within 200m of a roadway with >50k-vpd; however, almost half lived within 200m of a roadway with >10k-vpd. Epidemiologic models were adjusted for demographic, socioeconomic, parental, and random school effects. Results: As expected from a GIS-based model, estimated NO2 concentration increased by 4.8ppb [95%CI: 2.7, 6.8], 3.2ppb [2.7, 3.7], and 2.6ppb [2.4, 2.9] per km increase in proximity to >10k, >50k, and >90k-vpd roadways, respectively. NO2 concentration estimated through land-use regression modeling was positively associated with current asthma (OR=1.7 [1.1, 2.6] for 10ppb NO2). Proximity to roadways with >50k-vpd was positively associated with current asthma (OR =1.1 [1.02, 1.2] for 1.5km). There were also marginally significant associations between current asthma and proximity to roadways with >10k and >90k-vpd (OR =1.5 [0.97, 2.4] for 1.5km and OR =1.04 [1.0, 1.1] for 1.5km, respectively). Discussion and Conclusions: These results provide evidence that adverse health affects associated with traffic-related air pollution occur well beyond a narrow (200m) buffer area surrounding major roadways, potentially impacting children living several kilometers away from these roadways. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.