Figure 4. Effect of combined exposure to air pollutants during pregnancy and in the first year of life on the risk of eczema at 1 year of age. The direction of the association between exposure to air pollutants and childhood eczema was set as positive. The model was adjusted for paternal atopy, maternal work during pregnancy, maternal primipara, monthly household income, open windows often, and use air purifier.
Pollutants during pregnancy, one year after birth, and the second year after birth were all included in the WQS model. For per 25 percentiles increased in the WQS index of combined exposure to pollutants, the risk of cumulative eczema in children before 2 years of age increased by 1.28 times (95%CI : 1.06-1.55), in which O3 in pregnancy played a major role (Figure 5).