Air pollution may make coronavirus more severe for some patients

Long-term exposure to urban air pollution may have made the novel coronavirus (COVID-19) more deadly for some, according to a new study by researchers at Emory University and published in the journal The Innovation.

The researchers analyzed key urban air pollutants, including fine particle matter (PM2.5), nitrogen dioxide (NO2), and ozone (O3), across 3,122 counties in the United States from January to July 2020. To examine the association between ambient air pollutants and the severity of COVID-19 outcomes, the researchers investigated two major death outcomes, the case-fatality rate, or the number of deaths among the people who are diagnosed with COVID-19, and the mortality rate, or the number of COVID-19 deaths in the population. The two indicators can imply the biological susceptibility to deaths from COVID-19 and offer information of the severity of the COVID-19 deaths in the general population, respectively, the researchers said.

Of the pollutants analyzed, NO2 had the strongest independent correlation with raising a person's susceptibility to death from COVID-19, according to the study. A 4.6 parts per billion (ppb) increase of NO2 in the air was associated with 11.3 percent and 16.2 percent increases in COVID-19 case-fatality and mortality rate, respectively.

Additionally, the researchers said they discovered that just a 4.6 ppb reduction in long-term exposure to NO2 would have prevented 14,672 deaths among those who tested positive for the virus. The team said they also observed a margin-ally significant association between PM2.5 exposure and COVID case-fatality rate, whereas no notable associations were found with O3.

"Long-term exposure to urban air pollution, especially nitrogen dioxide, might enhance populations' susceptibility to severe COVID-19 death outcomes," said Donghai Liang, co-author of the study, in a statement. "It's essential to deliver this message to public health practitioners and policymakers in order for them to consider protecting vulnerable populations that lived in historically high NO2 pollution."

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