Air pollution and COVID-19 mortality in Chinese cities: insights from a multi-city analysis during the pandemic’s first wave

This study investigated the association between air pollutant exposure and COVID-19 mortality using a generalized additive model (GAM) with a negative binomial distribution, analyzing data from 45 Chinese cities. The pollutants assessed were nitrogen dioxide (NO2), sulfur dioxide (SO2), ozone (O3), and particulate matter (PM2.5). Results showed that a 10 µg/m3 increase in NO2 was associated with a 28.3% rise in COVID-19 mortality risk (RR = 1.283, 95% CI: 1.143–1.351). PM2.5 significantly increased mortality risk only in Wuhan (RR = 1.212, 95% CI: 1.110–1.323). In contrast, SO2 and O3 were protective, with O3 reducing mortality risk by up to 11.1% at certain lag periods. Stratified analysis indicated a markedly stronger effect of NO2 in southeastern regions. These findings highlight the need to address air pollution in pandemic preparedness and call for further research on its regional impacts to guide targeted public health interventions.