Effects of early life exposure to outdoor air pollution and indoor renovation on childhood asthma in China

Recent rapid increase of childhood asthma in China should be associated with exposure to the high air pollution, but it is unclear to which exposure window, to which kind of air pollution, and to what extent the effect. We investigated the effect of early life exposure to both outdoor and indoor air pollution on childhood asthma. Questionnaire survey was administered to 2490 children aged 3-6 years in Changsha. Early life exposure of each child in utero and during the first year of life was evaluated based on three outdoor air pollutants, i.e. particulate matters (PM10), industry-related SO2 and traffic-related NO2, and two kinds of indoor air pollution represented by new furniture and redecoration. Multivariate logistic regression method was used to estimate the effect of exposure on asthma. Results indicated that exposure to both industry- and traffic-related air pollutants (SO2 and NO2) significantly increased childhood asthma with odds ratio = 1.07 (95% CI: 1.03-1.12) and 1.16 (1.00-135) in utero and 1.09 (1.04-1.15) and 1.26 (1.06-1.50) during the first year for 10 mu g/m(3) increase in concentration. Exposure to new furniture and home redecoration during pregnancy significantly increased childhood asthma with odds ratio 234 (1.16-4.74) and 2.21 (1.29-3.81) respectively. The effects of outdoor and indoor exposures were independent to each other. We conclude that early life exposures to both outdoor air pollution and indoor renovation contributes to the rapid development of childhood asthma in China, the former stronger after birth but the latter stronger before birth. (C) 2015 Elsevier Ltd. All rights reserved.