Association between air pollution and COVID-19 infection: evidence from data at national and municipal levels

The impact of high concentrations of air pollution on COVID-19 has been a major air quality and life safety issue in recent studies. This study aimed to assess the contribution of different air pollution indicators in different spaces on the newly confirmed cases of coronavirus. According to causality’s results between air pollution (AP) and COVID-19 infection in 9 countries, first, we examined the non-linear relationship from AP to COVID-19 with PM(2.5) as the rating variable (the cut point is 35 μg/m(3)) at the national level. It is concluded that the effects of PM(2.5) and PM(10) on COVID-19 are more sensitive in Russia, England, Germany, and France, while O(3) and PM(2.5) are more sensitive in America and Canada from 21 Jan to 20 May. Second, we examined the threshold effects from AP to COVID-19 with PM(2.5), PM(10), SO(2), CO, NO(2), and O(3) as the threshold variables, respectively, at the municipal level in China during the period 28 Jan to 31 May. It is concluded that except CO, the remaining 5 indicators are very sensitive to the increase of newly confirmed cases, and the spread of COVID-19 can be prevented and controlled by the determination of thresholds. In addition, the 9 countries and 27 provinces show that PM(2.5) in high concentrations is the more sensitive pollutant on the spread of COVID-19 infection.