Personal and indoor PM2.5 exposure from burning solid fuels in vented and unvented stoves in a rural region of China with a high incidence of lung cancer

Abstract

The combustion of biomass and coal is the dominant source of household air pollution (HAP) in China, and contributes significantly to the total burden of disease in the Chinese population. To characterize HAP exposure related to solid fuel use and ventilation patterns, an exposure assessment study of 163 nonsmoking female heads of households enrolled from 30 villages was conducted in Xuanwei and Fuyuan, two neighboring rural counties with high incidence of lung cancer due to the burning of smoky coal (a bituminous coal, which in health evaluations is usually compared to smokeless coal - an anthracite coal available in some parts of the area). Personal and indoor 24-h PM2.5 samples were collected over two consecutive days in each household, with approximately one-third of measurements retaken in a second season. The overall geometric means (GM) of personal PM2.5 concentrations in Xuanwei and Fuyuan were 166 [Geometric Standard Deviation (GSD):2.0] and 146 (GSD:1.9) μg/m 3, respectively, which were similar to the indoor PM2.5 air concentrations [GM(GSD):162 (2.1) and 136 (2.0) μg/m3, respectively]. Personal PM2.5 was moderately highly correlated with indoor PM2.5 (Spearman r = 0.70, p < 0.0001). Burning wood or plant materials (tobacco stems, corncobs etc.) resulted in the highest personal PM2.5 concentrations (GM:289 and 225 μg/m3, respectively), followed by smoky coal, and smokeless coal (GM:148 and 115 μg/m3, respectively). PM2.5 levels of vented stoves were 34-80% lower than unvented stoves and firepits across fuel types. Mixed effect models indicated that fuel type, ventilation, number of windows, season, and burning time per stove were the main factors related to personal PM 2.5 exposure. Lower PM2.5 among vented stoves compared with unvented stoves and firepits is of interest as it parallels the observation of reduced risks of malignant and nonmalignant lung diseases in the region.