This report, available for downloading below, presents a study that evaluated whether there is an association between exposure to outdoor air pollution and the risk of COVID-19 incidence, hospitalization, and mortality in a large cohort of Danish adults.
Dr. Zorana Andersen of the University of Copenhagen, Denmark, and her colleagues sought to identify the most susceptible populations by socioeconomic status, ethnicity, and those with existing health problems. They followed 3.7 million adults in Denmark between March 2020 and April 2021, focusing on five outdoor air pollutants: fine particulate matter, known as PM2.5 (particles less than 2.5 micrograms in diameter), coarse particulate matter, known as PM10 (particles less than 10 micrograms in diameter), black carbon, nitrogen dioxide, and ozone.
The findings showed elevated risks of COVID-19 incidence, hospitalizations, and death associated with long-term exposure to PM2.5, PM10, black carbon, and nitrogen dioxide. Researchers did not find associations between exposure to ozone and COVID-19 incidence. Overall, older adults and lower socioeconomic populations had the greatest risk of contracting COVID-19.
Risks of increased COVID-19 incidence and hospitalizations were strongest with exposure to nitrogen dioxide, which is produced from combustion of fossil fuels, especially in motor vehicles. The risk of COVID-19 mortality, however, was strongest with exposure to fine particulate matter, for which major sources include industrial and agricultural activities, wildfires, and fuel combustion.