Characterization of ambient-generated exposure to fine particles using sulfate as a tracer in the Chinese megacity of Guangzhou

Total personal exposures can differ from the concentrations measured at stationary ambient monitoring sites. To provide further insight into factors affecting exposure to particles, chemical tracers were used to separate total personal exposure into its ambient and non-ambient components. Simultaneous measurements of ambient and personal exposure to fine particles (PM2.5) were conducted in eight districts of Guangzhou, a megacity in South China, during the winter of 2011. Considerable significant correlations (Spearman's Rho, r(s)) between personal exposures and ambient concentrations of sulfate (SO42-; r(s)> 0.68) were found in contrast to elemental carbon (EC; r(s) > 037). The average fraction of personal SW to ambient SO42- resulting in an adjusted ambient exposure factor of cc = 0.72 and a slope of 0.73 was determined from linear regression analysis when there were minimal indoor sources of SO42-. From all data pooled across the districts, the estimated average ambient -generated and non-ambient -generated exposure to PM2.5 were 55.3 mu g/m(3) (SD = 23.4 mu g/m(3)) and 18.1 mu g/m(3) (SD = 29.1 mu g/m(3)), respectively. A significant association was found between ambient -generated exposure and ambient PM2.5 concentrations (Pearson's r = 0.51, p < 0.001). As expected, the non-ambient generated exposure was not related to the ambient concentrations. This study highlights the importance of both ambient and non-ambient components of total personal exposure in the megacity of Guangzhou. Our results support the use of SO42- as a tracer of personal exposure to PM2.5 of ambient origin in environmental and epidemiological studies. (C) 2016 Elsevier B.V. All rights reserved