Potential health benefit of reducing household solid fuel use in Shanxi province, China.

Indoor air pollution from solid fuel use has severe health effects. 60% of the Chinese population lives in rural areas, where most people rely on solid fuels for cooking and heating. We estimate exposure by combining information on the amount of time spent in different microenvironments and estimates of the particle concentrations (PM(10)) in these environments. According to our estimates, 70% of the exposure experienced by the rural population is due to indoor air pollution (IAP). The urban coal using population experience a 17% increase in exposure from IAP. We apply Monte Carlo simulations to quantify variability and uncertainty in the exposure, morbidity and mortality estimates. We find that applying Monte Carlo simulations reduces the estimated uncertainty compared to analytical methods based on approximate distributions and the central limit theorem. We find that annually about 4% (geometric S.D. sigma(g), 3.2) and 35% (sigma(g), 2.6) of the deaths in the urban and rural populations, respectively, could be avoided by switching to clean fuels. Upgrading the stoves in rural areas to the standard found in urban areas is estimated to reduce mortality by 23% (sigma(g), 3.1). Moreover, we estimate that chronic respiratory illness (CRI) in children can be reduced by, respectively, about 9% (sigma(g), 2.5) and 80% (sigma(g) 1.9) by switching to clean fuels in the urban and rural areas. Upgrading the stoves in rural areas is estimated to reduce CRI in children with about 58% (sigma(g) 2.3). For adults the reduction in CRI was estimated to be 6% (sigma(g) 2.4) and 45% (sigma(g) 1.8) for the urban and rural population following a fuel switch, and 31% (sigma(g) 2.4) for the rural population from stove improvements. Contrary to our expectations we find small gender differences in exposure. We ascribe that to comparable kitchen and living area concentrations and similar indoor occupation times for the genders. Young children and the elderly spend the most time indoors, and have the highest daily exposure in the coal using population. The rural population experience higher exposure than the urban population, even though the outdoor air is significantly cleaner in rural areas.