Indoor air pollution and lung function growth among children in four Chinese cities.

UNLABELLED: Ambient air pollution has been associated with decreased growth in lung function among children; but little is known about the impact of indoor air pollution. We examined relationships between indoor air pollution metrics and lung function growth, among children (n = 3273) aged 6-13 years living in four Chinese cities. Lung function parameters (FVC and FEV(1) ) were measured twice a year. Questionnaires were used to determine home coal burning and ventilation practices. Generalized estimating equations were used to examine associations. Use of coal as a household fuel was associated with 16.5 ml/year lower (33%, P < 0.001) and 20.5 ml/year lower (39%, P < 0.001) growth in children's FEV(1) and FVC, respectively. FEV(1) growth was 10.2 ml/year higher (20%, P = 0.009), and FVC growth was 17.0 ml/year higher (33%, P < 0.001) among children who lived in houses with the presence of a ventilation device. Among children living in houses where coal was used as a fuel and no ventilation devices were present, adjusted FVC and FEV(1) growth, respectively, were 37% and 61% that of the average growth per year in the full cohort. This suggests that household coal use may cause deficits in lung function growth, while using ventilation devices may be protective of lung development. PRACTICAL IMPLICATIONS: Nearly 3.4 billion people use solid fuels in homes for cooking and/or heating. We report the following findings from a longitudinal study: (i) household coal use is significantly associated with reduction in children's lung function growth and (ii) the use of household ventilation devices is significantly associated with higher lung function growth, particularly among children living in households where coal is used as a fuel. These findings not only provide evidence that indoor coal use impairs children's lung development but also point to the importance of improving ventilation conditions in reducing harmful effects of indoor air pollution sources.