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Background: In Xuanwei County, Yunnan Province, China, lung cancer mortality rates in both males and females are among the highest in China., Methods: We evaluated differential effects of smoking on lung cancer mortality before and after household stove improvement with chimney to reduce exposure to smoky coal emissions in the unique cohort in Xuanwei, China. Effects of independent variables on lung cancer mortality were measured as hazard ratios and 95% confidence intervals using a multivariable Cox regression model that included separate time-dependent variables for smoking duration (years) before and after stove improvement., Results and Conclusion: We found that the effect of smoking on lung cancer risk becomes considerably stronger after chimney installation and consequent reduction of indoor coal smoke exposure.

Unlabelled: Diverse indoor combustion sources contribute to the indoor air environment. To evaluate the effect of these sources on human respiratory health, we examined associations between respiratory conditions and household factors in the 2360 children's fathers (mean = 38.4 years old) and associations between lung function and household factors in 463 primary school children (mean = 8.3 years old) from Wuhan, China. Factor analysis developed new uncorrelated 'factor' variables. Unconditional logistic regression models or linear regression models, controlling for important covariates, estimated the respiratory health effects. Coal smoke derived from home heating ('heating coal smoke') was associated with high adult reporting of persistent cough, persistent phlegm, and wheeze. Cooking coal smoke was associated with physician-diagnosed adult asthma and decreased forced vital capacity (FVC), and forced expiratory volume at 1 s (FEV(1)) in children. The presence of any home cigarette smoker was associated with more reports of persistent cough, persistent phlegm, cough with phlegm, and bronchitis. Our study suggests that in Wuhan, there may be independent respiratory health effects of different indoor combustion sources and their exposure factors for these study populations., Practical Implications: We conclude that multiple indoor air pollution sources could have adverse respiratory health effects on both children and middle-aged men in the city of Wuhan, China. These results may have implications for the Wuhan local government, the Chinese government, or other related organizations in efforts on protecting public health through regulation of indoor air pollution from indoor combustion sources.

In Xuan Wei County, Yunnan Province, lung cancer mortality is among China's highest and, especially in females, is more closely associated with indoor burning of "smoky" coal, as opposed to wood or "smokeless" coal, than with tobacco smoking. Indoor air samples were collected during the burning of all three fuels. In contrast to wood and smokeless coal emissions, smoky coal emission has high concentrations of submicron particles containing mutagenic organics, especially in aromatic and polar fractions. These studies suggested an etiologic link between domestic smoky coal burning and lung cancer in Xuan Wei.

The Chinese national pollution census has indicated that the domestic burning of solid fuels is an important contributor to nitrogen dioxide ( NO2) and sulfur dioxide ( SO2) emissions in China. To characterize indoor NO2 and SO2 air concentrations in relation to solid fuel use and stove ventilation in the rural counties of Xuanwei and Fuyuan, in Yunnan Province, China, which have among the highest lung cancer rates in the nation, a total of 163 participants in 30 selected villages were enrolled. Indoor 24-h NO2 and SO2 samples were collected in each household over two consecutive days. Compared to smoky coal, smokeless coal use was associated with higher NO2 concentrations [geometric mean ( GM) = 132 μg/m3 for smokeless coal and 111 μg/m3 for smoky coal, P = 0.065] and SO2 [limit of detection = 24 μg/m3; percentage detected (%Detect) = 86% for smokeless coal and 40% for smoky coal, P < 0.001]. Among smoky coal users, significant variation of NO2 and SO2 air concentrations was observed across different stove designs and smoky coal sources in both counties. Model construction indicated that the measurements of both pollutants were influenced by stove design. This exposure assessment study has identified high levels of NO2 and SO2 as a result of burning solid fuels for cooking and heating. [ABSTRACT FROM AUTHOR]