Exposure assessment,chemical characterization and source identification of PM2.5 for school children and industrial downwind residents in Guangzhou,China

To assess the exposure doses of PM_2.5 and to investigate its chemical components for the subpopulation (i.e., school children and industrial downwind residents), simultaneous sampling of indoor and outdoor PM_2.5 was conducted at an elementary school close to traffic arteries and a residence located in the downwind area of a steel plant in metropolitan Guangzhou in 2010. Chemical components, i.e., organic carbon, elemental carbon and 6 water soluble ions were analyzed in PM_2.5. A survey was also conducted to investigate the time-activity patterns of the school children and the industrial downwind residents. Indoor and outdoor PM_2.5 were 63.2 ± 20.1 and (76.7 ± 35.8) μg/m³ at the school, and 118.8 ± 44.7 and 125.7 ± 57.1 μg/m³ in the community, respectively. Indoor PM_2.5 was found to be highly related to outdoor sources, and stationary sources were the significant contributors to PM_2.5 at both sites. The daily average doses of PM_2.5 for the school children at the school (D _children) and the industrial downwind residents in the community (D _residents) were (7.6 ± 1.9) and (36.1 ± 36.8) μg/kg-day, respectively. The daily average doses of particulate organic mass and SO₄ ^2? were the two most abundant chemical components in PM_2.5. PM_2.5 exposure for the school children was contributed by indoor and outdoor environments by 48.8 and 51.2 %, respectively; for the industrial downwind residents, the contributions were 66.0 and 34.0 %, respectively. Age and body weight were significantly and negatively correlated with D _children, while age, body weight and education level were significantly and negatively correlated with D _residents; gender was not a significant factor at both cases.