Association between ambient NO₂ exposure and health status in a floating population: findings from 338 cities in China

Few studies investigated the effects of exposure to NO₂ on health status in the Chinese floating population. The present cross-sectional study evaluated the association of ambient NO₂ with health status in a floating population in China. Data on 168961 floating individuals in 338 cities were obtained from the 2017 China Migrants Dynamic Survey. The association between exposure to NO₂ and self-related health (SRH) status was assessed by binary logistic regression analysis, both in the entire subject cohort and in subgroups assorted by socioeconomic levels and demographic characteristics. The robustness of the associations between NO₂ exposure and health status was evaluated by sensitivity analyses. Each grade increment of annual average NO₂ exposure was found to increase the risk of poor SRH by 2.4% in the floating population (odds ratio [OR] = 1.024, 95% confidence interval [CI]: 1.011–1.038). When subgrouped by age, subjects in the floating population aged 31–49 years had the highest NO₂ associated health risk (OR = 1.036, 95% CI: 1.018–1.054). When subgrouped by per capita gross domestic product (PGDP), subjects in regions with mid-level PDGP had the highest NO₂ associated SRH (OR = 1.116, 95% CI: 1.091–1.141). These findings indicated that exposure to NO₂ increases the risk of poor SRH in the floating population, with individuals aged 31–49 years and those living in mid-level PGDP regions being more sensitive to the adverse effects of NO₂. More effective strategies to reduce air pollution may improve the health status of the floating population in China.