Background: The incidence of eczema is higher in children aged 0-2 years, but the long-term effect of air pollutants exposure in early life on the risk of eczema development is unclear. Methods: We conducted a birth cohort study in Jinan, China, to explore the effect of early life air pollutant exposure on the risk of eczema in younger children. An inverse distance weighting method was used for individual exposure assessment. Binary and multivariate logistic models were used to investigate the effects of air pollutants on eczema, the distributed lag model to find sensitive windows of exposure, weighted quantile sum model and principal component analysis to explore the combined effects of multiple pollutants. Results: The cumulative incidence rate for eczema among 5819 children aged 2 was 19.8%. Exposure to high levels of O ₃ during pregnancy ( OR 1.12, 95% CI 1.06-1.19) and during the first year after birth ( OR 1.24, 95% CI 1.03-1.50) increased the risk of eczema. PM _2.5-10 during pregnancy ( OR 1.31, 95% CI 1.20-1.43), PM _2.5 ( OR 1.08, 95% CI 1.01-1.15) and PM _2.5-10 ( OR 1.07, 95% CI 1.00-1.14) during the first year after birth also increased the risk of eczema. The critical window for O ₃ and PM exposure was the third trimester and early postnatal period. Moreover, in the combined effect of multiple pollutants, O ₃ played a dominant role during pregnancy (weighting > 0.3), with a predominantly O ₃ principal component associated with eczema risk (adjusted OR 1.011, 95% CI 1.007-1.015). Conclusions: Exposure to air pollutants O ₃ and PM in early life increased the risk of eczema at 0-2 years of age, and the sensitivity window appeared earlier. O ₃ exposure during pregnancy played a key role in the combined effect of pollutants on eczema risk.