Seasonal differences in household air pollutants and determinants of personal air pollution exposure in rural women cooking and heating with biomass fuels in the Tibetan Plateau

Abstract

Cooking and heating with traditional biomass stoves impacts climate and population health. The very limited information on personal exposures to biomass smoke and its major determinants limits intervention evaluation and the estimation of dose-response relationships and attributable disease burden We enrolled 204 Chinese women in Sichuan, China who cooked with biomass, and measured their seasonal 48-h personal exposures to PM2.5 and CO and 48-h kitchen PM2.5, elemental and organic carbon (EC/OC), and CO and NOx concentrations in the baseline assessment of an energy intervention study. We measured daily outdoor PM2.5 and collected information on demographics, household energy use and ventilation, among others. Multivariate regression models were used to assess the environmental, household, and individual determinants of women’s PM2.5 exposure. Women’s geometric mean 48-h exposure to PM2.5 was 80 μg/m3 (95% CI: 74, 87) in summer and twice as high in winter (169 μg/m3, 95% CI: 150, 190). OC/EC and NOx ratios also differed by season (summer: OC/EC = 9.4 (7.9, 11.1), NO/NO2 = 40 (12, 140); winter: OC/EC = 14.8 (11.6, 18.8); NO/NO2 = 86 (44, 165)). In winter, the most significant decreases in personal PM2.5 exposures were for women heating with electricity or wood-charcoal (-25% (-52, 1) and who used frequent kitchen ventilation (-37% (-78, -3)), while the most significant increase in exposure was for women with a barrier separating the fuel loading area from the kitchen (73% (31, 114)). In summer, primary use of a gaseous fuel or electricity for cooking (-37% (-67, -7)) and outdoor PM2.5 (11 (6, 16)) had the largest impacts on personal PM2.5 exposure. Outdoor and household air pollution were significant predictors of women’s PM2.5 exposure. Use of cleaner-burning fuels could lower PM2.5 exposures in this region and may impact levels of climate-relevant pollutants (EC, OC).