The effects of urban green space and road proximity to indoor traffic-related PM2.5, NO2, and BC exposure in inner-city schools

Background Since there are known adverse health impacts of traffic-related air pollution, while at the same time there are potential health benefits from greenness, it is important to examine more closely the impacts of these factors on indoor air quality in urban schools. Objective This study investigates the association of road proximity and urban greenness to indoor traffic-related fine particulate matter (PM 2.5 ), nitrogen dioxide (NO 2 ), and black carbon (BC) in inner-city schools. Methods PM 2.5 , NO 2 , and BC were measured indoors at 74 schools and outdoors at a central urban over a 10-year period. Seasonal urban greenness was estimated using the Normalized Difference Vegetation Index (NDVI) with 270 and 1230 m buffers. The associations between indoor traffic-related air pollution and road proximity and greenness were investigated with mixed-effects models. Results The analysis showed linear decays of indoor traffic-related PM 2.5 , NO 2 , and BC by 60%, 35%, and 22%, respectively for schools located at a greater distance from major roads. The results further showed that surrounding school greenness at 270 m buffer was significantly associated ( p