Air pollution connected to higher COVID-19 death rates

A new study of more than 3,000 counties in the U.S. finds a correlation between higher levels of particulate air pollution and higher death rates from COVID-19.

Why it matters: COVID-19 may be caused by the novel coronavirus, but the outcome of an infection is influenced by everything from age to race to the environment. Understanding the connection between disease and pollution can help us address those risks going forward.

By the numbers: In a study published today in Science Advances, researchers from the Harvard T.H. Chan School of Public Health found every increase of one microgram of fine-particle air pollutants at the county level was associated with an 11% increase in that county's COVID-19 mortality rate.

• That result echoes earlier preprint research by the same team from the earliest weeks of the pandemic showing that air pollution was connected to worse outcomes from COVID-19.

The catch: The researchers caution that because individual-level data on COVID-19 outcomes for large, representative populations doesn't yet exist, it's difficult to be certain that air pollution is connected to coronavirus deaths.

• People who live in areas with high levels of air pollution are also more likely to be poor and Black — two factors also associated with higher levels of COVID-19 death rates.

Yes, but: As Jeremy Jackson and Kip Hodges point out in an accompanying editorial, science has clearly established air pollution is a risk factor for death from cardiovascular and pulmonary diseases, which perfectly describes COVID-19.

• Threats from new diseases "are likely to be exacerbated by air pollution, even at the levels currently attained in the United States despite conscientious efforts to improve air quality," Jackson and Hodges write.

The bottom line: We now understand the novel coronavirus can be airborne, and so are the air pollutants that appear to make the disease that much worse.