Risk of COVID-19 is associated with long-term exposure to air pollution

High risk of severe disease of COVID-19 has been associated with patients with chronic obstructive pulmonary disease, cardiovascular disease or hypertension, and long-term exposure to PM2.5 has been associated with COVID-19 mortality. We collate individual level data of confirmed COVID-19 cases during the first wave of the epidemic in mainland China by March 6, 2020. We pair these data with a mobile phone dataset, covering human movements from Wuhan before the travel ban and inner-city movements during the time of emergency response from 324 cities in China. Adjusting for socio-economic factors, an increase of 10 μg/m3 in NO2 or PM2.5 was found to be associated with a 22.41% (95%CI: 7.28%-39.89%) or 15.35% (95%CI: 5.60%-25.98%) increase in the number of COVID-19 cases, and a 19.20% (95%CI: 4.03%-36.59%) or 9.61% (95%CI: 0.12%-20.01%) increase in severe infection, respectively. Our results highlight the importance of air quality improvements to health benefits.