Chemical composition and source apportionment of ambient, household, and personal exposures to PM 2.5 in communities using biomass stoves in rural China.

Fine particulate matter (PM _2.5 ) has health effects that may depend on its sources and chemical composition. Few studies have quantified the composition of personal and area PM _2.5 in rural settings over the same time period. Yet, this information would shed important light on the sources influencing personal PM _2.5 exposures. This study investigated the sources and chemical composition of 40 personal exposure, 40 household, and 36 ambient PM _2.5 samples collected in the non-heating and heating seasons in rural southwestern China. Chemical analysis included black carbon (BC), water-soluble components (ions, organic carbon), elements, and organic tracers. Source apportionment was conducted using organic tracer concentrations in a Chemical Mass Balance model. Biomass burning was the largest identified PM _2.5 source contributor to household (average, SD: 48 ± 11%) and exposures (31 ± 6%) in both seasons, and ambient PM _2.5 in winter (20 ± 4%). Food cooking also contributed to household and personal PM, reaching approximately half of the biomass contributions. Secondary inorganic aerosol was the major identified source in summertime ambient PM _2.5 (32 ± 14%), but was present in all samples (summer: 10 ± 3% [household], 13 ± 6% [exposures]; winter: 18 ± 2% [ambient], 7 ± 2% [household], 8 ± 2% [exposures]). Dust concentrations and fractional contribution to total PM _2.5 were higher in summer exposure samples (7 ± 4%) than in ambient or household samples (6 ± 1% and 2 ± 1%, respectively). Indoor sources comprised up to one-fifth of ambient PM _2.5 , and outdoor sources (vehicles, secondary aerosols) contributed up to 15% of household PM _2.5 . While household sources were the main contributors to PM _2.5 exposures in terms of mass, inorganic components of personal exposures differed from household samples. Based on these findings, health-focused initiatives to reduce harmful PM _2.5 exposures may consider a coordinated approach to address both indoor and outdoor PM _2.5 source contributors.
(Copyright © 2018. Published by Elsevier B.V.)