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Background Otitis media (OM) is a common infection in early childhood with repeated attacks that lead to long-term complications and sequelae, but its etiology still remains unclear. Objective To examine the association between early life exposure to air pollution and childhood OM, with the purpose of identifying critical windows of exposure and key components of air pollution in the development of OM. Methods We conducted a prospective cohort study of 1617 children aged 3–4 years in Changsha, China (2011–2012). The prevalence of OM was assessed by a questionnaire administered by the parents. Individual exposures to nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ) and particulate matter with an aerodynamic diameter ≤ 10 μm (PM 10 ) during prenatal, postnatal, and current windows were estimated using the measured concentrations at monitoring stations. We used logistic regression model to examine the OM risk in terms of odds ratio (OR) and 95% confidence interval (CI) for exposure to different air pollutants during different timing windows, adjusting for covariates, multi-pollutants, and multi-windows. Results Life-time prevalence of doctor-diagnosed OM in preschool children in Changsha was 7.3%. Childhood OM was associated only with prenatal exposure to the industrial air pollution with adjusted OR (95% CI) = 1.44 (1.09–1.88) for a 27 μg/m3 increase in SO 2 , particularly during the first trimester of pregnancy. We further found that prenatal SO 2 exposure was not associated with the repeated attacks but was associated with the onset of OM, adjusted OR (95% CI) = 1.47 (1.10–1.96). The association between prenatal SO 2 exposure and early childhood OM was robust after adjusting for other pollutants and windows. Sensitivity analysis indicated that the association was stronger in females, children with parental atopy, and children living in houses with cockroaches, new redecoration, and condensation on window pane during winter. Conclusion We provide new evidence that prenatal exposure to industrial air pollution is associated with early childhood OM in China and may contribute to the onset of childhood OM. Our findings are helpful in developing more effective preventative strategies for childhood OM. [ABSTRACT FROM AUTHOR]

Low birth weight (LBW) remains a major public health problem worldwide, yet its crucial environmental risk factors are still unclear. To examine the association between LBW (term and preterm LBW) and prenatal exposure to ambient air pollution and home environmental factors as well as their combination, in order to identify critical time window for exposure and key outdoor and indoor factors in LBW development. A cohort study of 3509 preschool children was performed in Changsha, China during the period 2011–2012. A questionnaire was conducted to survey each child's birth outcome and each mother's exposure to home environmental factors including parental smoking, new furniture, redecoration, mold/damp stains, window pane condensation, and household pets during pregnancy. Maternal exposure to inhalable particulate matter (PM 10), industrial air pollutant (SO 2), and traffic air pollutant (NO 2) was estimated during different time windows of gestation, including conception month, three trimesters, birth month, and whole gestation. Associations of term and preterm LBW with ambient air pollutants and home environmental factors were assessed by multiple logistic regression models in terms of odds ratio (OR) with 95% confidence interval (CI). Term LBW (TLBW) was significantly associated with exposure to ambient PM 10 during pregnancy, with OR (95% CI) = 1.47 (1.00–2.14) for per IQR increase after adjustment for the covariates and home environmental factors. Specifically, we identified the significant association in early phase of pregnancy including conception month (1.90, 1.09–3.30) and the first trimester (1.72, 1.10–2.69). We further found that TLBW was significantly related with parental smoking at home, OR (95% CI) = 2.17 (1.09–4.33). However, no association was observed for preterm LBW (PLBW). The TLBW risk of ambient air pollution and home environmental factors was independent each other and hence the combined exposure to ambient PM 10 and indoor parental smoking caused the highest risk. Sensitivity analysis suggested that foetus with younger mothers were significantly more susceptible to risk of indoor parental smoking, while those with smaller house and cockroaches were more sensitive to risk of outdoor PM 10 exposure. Prenatal exposure to combined outdoor and indoor air pollution, particularly in critical window(s) during early pregnancy, significantly increases the risk of term LBW. • Air pollution was associated with term low birth weight (LBW) but not with preterm LBW. • We found term LBW was associated with prenatal exposure to ambient inhalable particle (PM 10). • Term LBW was also related with parental smoking at home during pregnancy. • Exposure to combined outdoor and indoor air pollution posed the highest risk of term LBW. • Early pregnancy was identified as the most critical time window for exposure susceptibility. [ABSTRACT FROM AUTHOR]