Effects of Fine Particulate Matter and Its Constituents on Asthmatic and Allergic Symptoms in Preschool Children: A Cross-Sectional Study in Six Cities of China

Abstract

Background/Aim: Few studies examined the effects of specific PM2.5 constituents on childhood asthma and allergy in China. We aimed to investigate the effects of various PM2.5 constituents on asthmatic and allergic symptoms in preschool children in China.Methods: A cross-sectional study was conducted among 48219 preschool children in six cities (Shanghai, Nanjing, Chongqing, Changsha, Urumqi and Taiyuan) based on China , Children ,Home and Health (CCHH) project in China. Information on allergic symptoms as well as demography were collected by questionnaires. Data for ambient PM2.5 concentration and its 5 constituents: BC, NH4+, SO42-, NO3- and OC were obtained from the global burden disease project to 205 kindergartens at a spatial resolution of 0.01×0.01(1km×1km) in six cities. A hierarchical logistic regression model was performed to explore the associations between kindergarten-level PM2.5 components and individual-level outcomes of asthmatic and allergic symptoms controlling for demography and other covariates.Results: A total of 30759 participants (51.7% male) were finally completed the study due on the missing data. Both the single-pollutant and two-pollutants model showed that ambient PM2.5 per 10ug/m3 increase positively associated with the prevalence of diagnosed asthma by an adjusted odds ratio (AOR) and 95% confidence interval(CI) of 1.18(1.01-1.35) and 1.13(1.02-1.24), respectively. Furthermore, the concentration of SO42- and NO3- were significantly associated with the prevalence of asthma and current rhinitis by the AOR for each 1ug/m3 increase in SO42-, and NO3- concentrations of 1.09(1.03-1.15) for asthma and 1.04(1.00-1.07) for current rhinitis, respectively.Conclusion: Components of PM2.5, especially NO3- and SO42- exposure were associated with asthmatic and allergic diseases in preschool children in China. Considering the related sources and combustion, it may represents an preventable risk factor for childhood asthma and allergic diseases.