ABSTRACT
Background: Previous studies have suggested the relation between outdoor air pollution and the onset risk of Corona Virus Disease 2019 (COVID-19). However, there is a lack of data related to the severity of the disease, especially in China. Methods We recruited a group of COVID-19 patients diagnosed in a recent large-scale outbreak caused by Delta variants in eastern China. We collected ambient air pollution data of the same period where the case occurred and applied a generalized linear model (GLM) to analyze the effects of short-term outdoor ambient particulate matter (PM) exposure on the risk of severe COVID-19. Results A total of 476 confirmed adult patients were recruited, of which 42 (8.82%) had a severe illness. With a unit increase in PM 10 , the risk of severe COVID-19 increased by 47.64% (95% confidence interval [CI]: 27.67, 70.73) at lag 0-14 days, 65.00% (95% CI: 35.18, 101.40) at lag 0-21 days, and 69.44% (95% CI: 37.03, 109.50) at lag 0-28 days, respectively. The association remained significant at lag 0-14 days or 0-28 days in the multi-pollutant models. With a unit increase in PM 2.5 , the risk of severe COVID-19 increased by 49.47% (95% CI: 19.61, 86.78) at lag 0-14 days, 97.61% (95% CI: 45.92, 167.60) at lag 0-21 days, and 120.27% (95% CI: 56.53, 209.98) at lag 0-28 days, respectively. The association remained significant at lag 0-21 days or 0-28 days in the multi-pollutant models. Conclusions Our results indicated that short-term exposure to outdoor PM was positively related to the risk of severe COVID-19, and reducing air pollution may contribute to the control of COVID-19.