Higher Air Pollution Is Linked To A Higher COVID-19 Death Rate, A New Study Finds

The distant Los Angeles skyline rises from an urban sprawl
Air pollution in Los Angeles has vastly improved since 1970, when California was granted the authority to set emissions standards that are tighter than federal standards. Thirteen other states have adopted California’s standards. (Photo by alpe89 via Flickr/Creative Commons)

Long-term exposure to high levels of air pollution increases the risk of death related to COVID-19, according to a new study from Harvard University.

That’s especially concerning in Southern California, where Los Angeles, Riverside and San Bernardino counties regularly rank among the worst in the nation for long-term particulate matter pollution, or PM2.5.

And, as is true in other parts of the nation, the effects of that pollution disproportionately harm Latinos, African Americans, Asian Americans and low-income communities — which underscores early data showing black Americans are dying at higher rates from COVID-19 complications.

The Harvard study gathered data from roughly 3,000 U.S. counties, which account for 90% of confirmed COVID-19 deaths nationwide, as of April 4. Researchers factored in population size, the number of hospital beds, the number of individuals tested, weather, plus some “socioeconomic and behavioral variables” like smoking.

That data was checked against county-level data on long-term exposure to PM2.5, which is generally measured by microgram per cubic meter of air.

According to the findings, an increase of just one microgram per cubic meter of air was associated with a 15% increase in the COVID-19 death rate.

L.A. County is dark red, indicating high particulate matter

“The results of this paper suggest that long-term exposure to air pollution increases vulnerability to experiencing the most severe COVID-19 outcomes,” the authors wrote.

The study has been submitted to The New England Journal of Medicine for review.

What is particulate matter?

The Environmental Protection Agency describes PM2.5 as “fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller.” Most PM2.5 comes from emissions generated by cars and trucks, power plants, and industrial sites.

Exposure to particulate matter has been linked to harmful health conditions including asthma, decreased lung function and complications for people with heart or lung disease. Many of those same conditions put people who contract COVID-19 at a higher risk of falling severely ill, according to the CDC.

“There is a large overlap between the diseases that are affected by fine particulate matter and diseases that lead to death if you get COVID-19,” said Dr. Francesca Dominici, a professor of biostatistics at the Harvard T.H. Chan School of Public Health and the study’s senior author.

Dominici said the findings can serve as a guide for public health officials to strengthen distancing efforts, direct resources and prepare for more serious COVID-19 cases in regions with worse PM2.5 pollution.

Air pollution in southern California

Southern California skies may be remarkably clear right now, but our infamous air pollution is well documented.

The American Lung Association releases an annual “State of the Air” report, ranking U.S. counties and metropolitan areas with the worst air pollution. The Los Angeles-Long Beach metro area placed fifth in its most recent report for highest annual levels of PM2.5. Fresno and Bakersfield were ranked first and second, respectively.

Measuring by county, San Bernardino and Riverside counties placed sixth and eighth, respectively, for the U.S. counties with the highest year-round PM2.5 pollution. L.A. County ranked 15th. Thirteen of the 20 worst counties for PM2.5 levels were in California.

Dominici singled out L.A., Orange and Fresno counties as “among the most polluted counties in the United States” based on her team’s research.

“For California counties that are most polluted, what it means is that… unfortunately, we’re expecting higher risk of death [from] COVID,” she told LAist today. “You are dealing with a population that is already susceptible to adverse health effects of COVID, because their lungs have been already exposed to many years of fine particulate matter.”

San Bernardino and Riverside counties also lead the nation in ozone pollution levels, better known as smog. L.A. County is ranked third for a SoCal hat trick.

Harvard’s study did not examine ozone levels for possible links to COVID-19 mortality, but Dominici said her team plans to study that soon. She said she also wants to look further into the impact coronavirus is having on African Americans.

Harvard’s study is online and available to the public.

(Infographic by Riley Anderson)