COVID-19 Resource Center
COVID-19 Resource Center
Perspective from Emanuela Taioli, MD, PhD
Disclosures: Wu reports no relevant financial disclosures.
November 19, 2020
2 min read

Small rise in long-term air pollution exposure may increase risk for COVID-19 death

Perspective from Emanuela Taioli, MD, PhD
Disclosures: Wu reports no relevant financial disclosures.
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An increase of 1 microgram per cubic meter in a U.S. county’s long-term average exposure to fine particle pollutants appeared to raise that area’s COVID-19 mortality rate, data from a preliminary ecological regression analysis show.

“The SARS‐CoV‐2 virus can attack a patient’s lungs as well as cardiovascular system,” Xiao Wu, a PhD candidate in the department of biostatistics at the Harvard T.H. Chan School of Public Health, told Healio Primary Care. “Therefore patients, especially those with preexisting conditions, may require extra measures to protect themselves from severe air pollution.”

Amid Air Pollution, a Woman Wears a Mask
A preliminary ecological regression analysis showed that counties with long-term exposure to air pollution particles smaller than the average human hair could increase that area’s COVID-19 mortality rate. Photo source: Adobe Stock. 

Previous research, Wu said, has linked long-term exposure of particulate matter less than 2.5 micrometers in diameter (PM2.5) to several adverse health outcomes, including asthma, worsening COPD, slowed lung function growth and increased risks for myocardial infarction, stroke and death from CVD. According to the Environmental Protection Agency’s website, the largest fine PM2.5 particle is about 30 times smaller than the average human hair, which is about 70 micrometers in diameter.

For the current analysis, Wu and colleagues analyzed daily PM2.5 exposures from 2000 to 2016 in 3,089 counties, accounting for 98% of the United States’ population, using what they described as “well-validated atmospheric chemistry and machine learning models.”

Xiao Wu

The researchers wrote in Science Advances that their analysis showed for each microgram per cubic meter increase in a county’s long-term average PM2.5, there was an 11% (95% CI, 6-17) increase in that area’s COVID-19 mortality rate. This rate remained stable as more data accumulated, according to the researchers.

In addition, age distribution, days since the first COVID-19 case was reported in a county, median household income, percent of owner-occupied housing, percent of the adult population with less than high school education, percent of Black residents and population density were important predictors of the COVID-19 mortality rate. Wu and colleagues reported a 49% (95% CI, 38-61) increase in COVID-19 mortality rate for every one standard deviation increase in the percent of Black residents in a county.

Wu said that more representative and individual-level data are needed to validate the findings.

“Physicians are often the first group of people to collect these data,” Wu said. “If physicians can collect and share these data in a privacy‐protected manner, foster collaborative data consortium and are willing to collaborate with environmental scientists and data scientists to analyze data for rigorous evaluation, this would be a significant step to prompt environmental policy change.”

In a related editorial, Jeremy Jackson and Kip Hodges, both members of Science Advances’ editorial team, wrote that COVID-19 is the latest “potentially severe emerging zoonotic disease” aggravated by air pollution that “remains a long-term threat to our species.” They encouraged future research to build on the findings of Wu and colleagues’ study.


EPA. Particulate Matter (PM) pollution. Accessed November 12, 2020.

Jackson J, Hodges K. Science Advances. 2020;doi:10.1126/sciadv.abf1897.

Wu X, et al. Science Advances; 2020:doi:10.1126/sciadv.abd4049.