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/m(3) at the school, and 118.8 ± 44.7 and 125.7 ± 57.1 μg/m(3) 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 SO(4)(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.