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 (NO 2 ), sulfur dioxide (SO 2 ), ozone (O 3 ), and particulate matter (PM 2.5 ). Results showed that a 10 µg/m 3 increase in NO 2 was associated with a 28.3% rise in COVID-19 mortality risk (RR = 1.283, 95% CI: 1.143–1.351). PM 2.5 significantly increased mortality risk only in Wuhan (RR = 1.212, 95% CI: 1.110–1.323). In contrast, SO 2 and O 3 were protective, with O 3 reducing mortality risk by up to 11.1% at certain lag periods. Stratified analysis indicated a markedly stronger effect of NO 2 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.