Yuanyuan Zhang1, Zhouxin Yin1, Peixuan Zhou1, Liansheng Zhang1, Zhuohui Zhao2, Dan Norbäck3, Xin Zhang4, Chan Lu5, Wei Yu6, Tingting Wang7, Xiaohong Zheng8, Ling Zhang9, Yunquan Zhang10. 1. School of Public Health, Wuhan University of Science and Technology, Wuhan, China. 2. School of Public Health, Fudan University, Shanghai, China. 3. Department of Medical Sciences, Uppsala University, Uppsala, Sweden. 4. Research Centre for Environmental Science and Engineering, Shanxi University, Taiyuan, China. 5. Xiangya School of Public Health, Central South University, Changsha, China. 6. School of Civil Engineering, Chongqing University, Chongqing, China. 7. Shanghai University of Medicine and Health Sciences, Shanghai, China. 8. School of Energy and Environment, Southeast University, Nanjing, China. 9. School of Public Health, Wuhan University of Science and Technology, Wuhan, China; Hubei Province Key Laboratory of Occupational Hazard Identification and Control, Wuhan University of Science and Technology, Wuhan 430065, China. Electronic address: zhangling@wust.edu.cn. 10. School of Public Health, Wuhan University of Science and Technology, Wuhan, China; Hubei Province Key Laboratory of Occupational Hazard Identification and Control, Wuhan University of Science and Technology, Wuhan 430065, China. Electronic address: YunquanZhang@wust.edu.cn.
Abstract
BACKGROUND: Emerging evidence suggests that early-life (in-utero and first-year since birth) exposure to ambient PM2.5 is a risk factor for asthma onset and exacerbation among children, while the hazards caused by PM2.5 compositions remain largely unknown. OBJECTIVE: To examine potential associations of early-life exposures to PM2.5 mass and its major chemical constituents with childhood asthma and wheezing. METHODS: By conducting the Phase II of the China, Children, Homes, Health study, we investigated 30,325 preschool children aged 3-6 years during 2019-2020 in mainland China. Early-life exposure to PM2.5 mass and its constituents (i.e., black carbon [BC], organic matter [OM], nitrate, ammonium, sulfate) were calculated based on monthly estimates at a 1 km × 1 km resolution from satellite-based models. We adopted a novel quantile-based g-computation approach to assess the effect of a mixture of PM2.5 constituents on childhood asthma/wheezing. RESULTS: The average PM2.5 concentrations during in-utero and the first year since birth were 64.7 ± 10.6 and 61.8 ± 10.5 µg/m3, respectively. Early-life exposures to a mixture of major PM2.5 constituents were significantly associated with increased risks of asthma and wheezing, while no evident compositions-wheezing associations were found in the first year. Each quintile increases in all five PM2.5 components exposures in utero was accordingly associated with an odds ratio of 1.18 [95% confidence interval: 1.07-1.29] for asthma and 1.08 [1.01-1.16] for wheezing. BC, OM and SO42- contributed more to risks of asthma and wheezing than the other PM2.5 constituents during early life, wherein the effects of BC were only observed during pregnancy. Sex subgroup analyses suggested stronger associations among girls of first-year exposures to PM2.5 components with childhood asthma. CONCLUSION: Early-life exposures to ambient PM2.5, particularly compositions of BC, OM and SO42-, are associated with an increased risk of childhood asthma.
BACKGROUND: Emerging evidence suggests that early-life (in-utero and first-year since birth) exposure to ambient PM2.5 is a risk factor for asthma onset and exacerbation among children, while the hazards caused by PM2.5 compositions remain largely unknown. OBJECTIVE: To examine potential associations of early-life exposures to PM2.5 mass and its major chemical constituents with childhood asthma and wheezing. METHODS: By conducting the Phase II of the China, Children, Homes, Health study, we investigated 30,325 preschool children aged 3-6 years during 2019-2020 in mainland China. Early-life exposure to PM2.5 mass and its constituents (i.e., black carbon [BC], organic matter [OM], nitrate, ammonium, sulfate) were calculated based on monthly estimates at a 1 km × 1 km resolution from satellite-based models. We adopted a novel quantile-based g-computation approach to assess the effect of a mixture of PM2.5 constituents on childhood asthma/wheezing. RESULTS: The average PM2.5 concentrations during in-utero and the first year since birth were 64.7 ± 10.6 and 61.8 ± 10.5 µg/m3, respectively. Early-life exposures to a mixture of major PM2.5 constituents were significantly associated with increased risks of asthma and wheezing, while no evident compositions-wheezing associations were found in the first year. Each quintile increases in all five PM2.5 components exposures in utero was accordingly associated with an odds ratio of 1.18 [95% confidence interval: 1.07-1.29] for asthma and 1.08 [1.01-1.16] for wheezing. BC, OM and SO42- contributed more to risks of asthma and wheezing than the other PM2.5 constituents during early life, wherein the effects of BC were only observed during pregnancy. Sex subgroup analyses suggested stronger associations among girls of first-year exposures to PM2.5 components with childhood asthma. CONCLUSION: Early-life exposures to ambient PM2.5, particularly compositions of BC, OM and SO42-, are associated with an increased risk of childhood asthma.