Breathing common airborne toxic chemicals could raise the risk of death from COVID-19, researchers conclude in a new study.
The study links a modest increase in cumulative exposure to dozens of hazardous air pollutants — as measured by a gauge known as the respiratory hazard index — to a 9% jump in COVID-19 mortality, according to the peer-reviewed paper published online today in the journal Environmental Research Letters.
To varying degrees, the connection also held for several individual pollutants such as acetaldehyde, a widely used organic chemical that EPA deems a "probable human carcinogen," and particulate matter in diesel exhaust.
"Possibly, chronic exposure to these pollutants at very low levels, while not causing observable respiratory system damages, do reduce the body's ability to recover from COVID-19 in some way," the paper says.
The findings may also help explain why residents of rural counties in states like Georgia and Louisiana have suffered higher death rates from the disease caused by the novel coronavirus than their urban counterparts, the researchers add.
The paper marks the latest addition to an expanding body of scientific literature tentatively tying air pollution exposure to higher odds of a fatal encounter with COVID-19, which has now killed more than 190,000 people in the United States.
To date, most studies have looked at the potential impact of ozone, nitrogen oxides and particulate matter — three pollutants for which EPA sets National Ambient Air Quality Standards.
At a scientific conference last month, for example, Emory University scientists linked a modest bump in nitrogen dioxide exposure to an 11% higher death rate (Greenwire, Aug. 27).
But the Clean Air Act classifies almost 190 other pollutants as hazardous because they may cause cancer or other serious health effects. The new study draws on data from EPA's 2014 National Air Toxics Assessment released in 2018.
While diesel-related particulate matter is not officially listed as a hazardous air pollutant under the law, it is measured in the air toxics assessment, Michael Petroni, a research fellow and Ph.D. candidate at the Center for Environmental Medicine and Informatics at the State University of New York's College of Environmental Science and Forestry, said in an email. The respiratory hazard index covers 40 to 50 pollutants, he said.
Along with Petroni and other scientists at the Syracuse, N.Y.-based school, the study's authors include a data researcher for the investigative online news outlet ProPublica, which incorporated the findings into a story published today.
The researchers acknowledge the limits of relying on the one-year estimates contained in the 2014 assessment but added that it "is the most recent and best data available."
They also question steps taken by EPA and some states to ease enforcement requirements for industry and other regulated entities in response to the pandemic. The result, they wrote, may be to "inadvertently exacerbate air quality issues in areas most vulnerable to increased COVID-19 mortality due to long-term air pollution exposures."
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