Personal exposure to fine particulate matter (PM2.5) of pregnant women during three trimesters in rural Yunnan of China

Little is known about fine particulate matter (PM2.5) exposure among pregnant women in rural China. This study aims to characterize exposure to PM2.5 among pregnant women in rural China, and investigate potential risk factors of personal exposure to PM2.5. The data were obtained from a birth cohort study that enrolled 606 pregnant women in Xuanwei, a county known for its high rates of lung cancer. The personal exposure to PM2.5 was measured using small portable particulate monitors during each trimester of pregnancy. Participants were interviewed using structured questionnaires that sought information on risk factors of PM2.5 exposure. The daily exposure to PM2.5 among the pregnant women ranged from 19.68 to 97.08 μg/m3 (median = 26.08). Exposure to PM2.5 was higher in winter and autumn than other seasons (p < 0.05); higher during the day than during the night (p < 0.001); and greater during cooking hours than during the rest of the day (p < 0.001). Using a mixed effects model, domestic solid fuel for cooking (β = 1.75, p < 0.001), winter and autumn (β = 2.96, p < 0.001), cooking ≥ once per day (β = 1.58, p < 0.05), heating with coal (β = 1.69, p < 0.001), secondhand smoke exposure (β = 1.59, p < 0.001) and township 1(β = 2.39, p < 0.001) were identified as risk factors for personal exposure to PM2.5 of pregnant women throughout pregnancy. Indirect effects of season and township factors on personal PM2.5 exposure were mediated by heating, cooking and domestic fuel using. In conclusion, PM2.5 levels in Xuanwei exceeded WHO guidelines. Seasonal and township factors and individual behaviors like domestic solid fuel using for cooking, heating with coal and secondhand smoke exposure are associated with higher personal PM2.5 exposure among pregnant women in rural China.