Associations of gestational and early life exposures to ambient air pollution with childhood atopic eczema in Shanghai, China.

Whether ambient air pollution is associated with childhood atopic eczema is controversial. In this paper, we selected 3358 preschool children who had not altered residences since pregnancy from a cross-sectional study during 2011-2012 in Shanghai, China, and obtained parent-reported data regarding childhood atopic eczema using an improved ISAAC questionnaire. We recorded daily concentrations of SO2, NO2, and PM10 throughout the child's lifetime (2006-2012), and calculated period-averaged concentrations for each district where the child lived to represent the child's exposure levels of these pollutants during different periods. In the multiple logistic regression analyses adjusted for potential confounders as well as for the other pollutants in the same periods, childhood atopic eczema was significantly associated with increments of NO2 in the approximate interquartile range (20μg/m3) during gestational period (adjusted OR, 95% CI for eczema lifetime-ever: 1.80, 1.29-2.49; for eczema in the year prior to the survey: 2.32, 1.57-3.43) and during the first year of life (2.00, 1.40-2.84; 2.16, 1.43-3.28). Exposure to elevated NO2 in the first two years, three years and total lifetime, as well as exposure to mixtures containing NO2 in each of these periods, were consistently associated with increased likelihood of childhood eczema. The highest odds ratios were found between exposure to a mixture of SO2 and NO2 during total lifetime (increment: 35μg/m3) and childhood eczema (adjusted OR, 95% CI: 2.80, 1.75-4.48; 3.50, 1.98-6.19). No significant associations were found between childhood eczema and ambient SO2 and PM10 individually or in mixtures. This study indicates that gestational and lifetime exposures to ambient NO2 are risk factors for atopic eczema in childhood. Exposure to ambient SO2 and PM10 may enhance the effect of NO2 exposure on childhood eczema.