Prenatal and postnatal exposures to ambient air pollutants associated with allergies and airway diseases in childhood: A retrospective observational study

It's inconsistent about associations of early exposures to outdoor air pollutants with allergies and airway diseases in childhood. Here, we investigated associations of prenatal and postnatal exposures to outdoor nitrogen dioxide (NO2), sulphur dioxide (SO2), and PM10 (particulate matter with an aerodynamic diameter <= 10 mu m) with asthma, wheeze, hay fever, rhinitis, pneumonia, and eczema in childhood. We surveyed 3,177 preschoolers who never change residences since birth in Shanghai, China. Parents reported information regarding children's health status. Daily-averaged concentrations of these pollutants in the children's gestation and in the first year of lifetime for district where children lived were collected by Shanghai Environmental Monitoring Center. After adjusting for covariates, exposures to higher level of NO2 during different trimesters of gestation and of the first year of lifetime had significant associations with the increased odds of asthma, hay fever, rhinitis, pneumonia, and eczema in childhood. Associations of NO2 exposures in the early trimesters of gestation and of the first year of lifetime with pneumonia were stronger than in the later trimesters, whereas associations of NO2 exposures in the early trimesters with hay fever and eczema were weaker than in the later trimesters. Our results indicated that prenatal and postnatal exposures to outdoor NO2 could be risk factors for allergies and airway diseases in childhood. Both dose and duration were related with the influence degree of early NO2 exposure on childhood allergies and airway diseases.