Association between short-term exposure to air pollution and COVID-19 hospital admission/mortality during warm seasons.

COVID-19 is a new viral infection that is usually accompanied by respiratory complications. Air pollution has been linked to cardiorespiratory-related diseases and even premature mortality. The short-term exposure to air pollution may aggravate pulmonary symptoms in COVID-19 patients. The relationship between the short-term exposure to air pollution and hospital admission and mortality resulting from COVID-19 will be examined in Tehran, Iran, during the spring and summer of 2020. The statistics of PM2.5, PM10, and 8-h maximum ozone (O3) concentrations, meteorological conditions, and COVID-19 hospital admissions/mortality were analyzed. The cross-correlation and temporal relationship between the daily concentration of the aforementioned pollutants (as well as the meteorological conditions) and the COVID-19 hospital admissions/mortality rate was calculated for each month. The concentration of PM2.5, PM10, and 8-h maximum O3, along with temperature, increased in the summer. The hospital admissions and mortality associated with COVID-19 decreased from the first peak in the spring and then increased to its second peak in the summer. The short-term exposure to ambient PM2.5, PM10, O3, and elevated temperatures is associated with higher rates of COVID-19-related hospital admissions/mortality throughout the summer. Among these variables, the correlation with O3 was statistically significant in more summer months. The short-term exposure to air pollution (especially O3) may increase the susceptibility of the population infected with COVID-19 and, therefore, increases the rate of hospital admissions and mortality even during the warm seasons.