CNN  — 

You are more likely to die from Covid-19 if you live in a county in the United States with higher levels of long-term air pollution, according to new research released Tuesday by Harvard T.H. Chan School of Public Health.

“We found that an increase of only 1 gram per cubic meter in fine particulate matter in the air was associated with a 15% increase in the Covid-19 death rate,” said lead author Francesca Dominici, co-director of the Harvard Data Science Initiative.

The study defined high pollution levels as fine particulate matter (PM 2.5) levels above 13 micrograms per cubic meter of air, much higher than the US mean of 8.4.

“The results suggest that long-term exposure to air pollution increases vulnerability to experiencing the most severe Covid-19 outcomes,” Dominici said.

The new information should be used by federal, state and local officials to make informed decisions about enforcing social distancing and preparing hospitals and local health care systems for a potential influx of more severe cases that will need extreme measures such as ventilators, Dominici said.

“We know the counties that have higher pollution levels historically,” she said. “We know that even if they [the counties] haven’t experienced high number of deaths yet, that would be one of their higher risks.”

US county level average of PM2.5 concentrations (2000- 2016)
Citation: Exposure to air pollution and COVID-19 mortality in the United States. Xiao Wu, Rachel C. Nethery, Benjamin M. Sabath, Danielle Braun, Francesca Dominici. medRxiv 2020.04.05.20054502

As for areas not currently seeing high mortality rates that should prepare, “Atlanta stands out as one of the clearest examples,” said co-author Xiao Wu, a Ph.D. student in the department of biostatistics at Harvard University.

“DeKalb and Gwinnett counties all have PM 2.5 levels greater than 13 micrograms per cubic meter of air across our study period, and still have a relatively low number of confirmed cases and deaths,” Wu said. “Baltimore as well stands out as a place with high PM exposure, but a low number of deaths for now.”

Wu said other counties with high pollution levels with current death rates from Covid-19 lower than the average across the US include:

  • Fresno, Kings, Los Angeles, Orange and Tulare counties in California
  • Vanderburgh county in Indiana
  • Butler, Hamilton and Montgomery counties in Ohio
  • Allegheny and Westmoreland counties in Pennsylvania

“That means that in these counties, we need to keep an even closer look to the social distancing measures, and we need to make sure that they are equipped to respond to those hospitalized with Covid-19,” Dominici said. “This is really, to me, utterly common sense.”

See related: CNN’s live tracker of Covid-19 cases across the US

The study is a “pre-print,” which means it has not undergone peer review and been accepted by a journal for publication. Pre-prints are becoming more and more common during the pandemic as researchers scramble to provide study results that might hold clues to fighting the virus.

The results provide “stark new information about the deadly toll of particle pollution,” said American Lu