Environment: Unequal air pollution exposure in the United States assessed

Populations in racially segregated communities in the USA may be more likely to be exposed to a form of air pollution with three times higher mass proportions of known toxic and carcinogenic metals, a study in Nature Communications suggests. The findings illustrate the disproportionate burden of air pollution faced by some populations and may help to inform regulations to reduce air pollution exposure.

Racially segregated communities represent the separation of populations by racial and ethnic groups, which results in a higher proportion of a certain racial or ethnic group living in a community than would be expected given the population over a larger area. Fine particulate matter (PM2.5) is a form of air pollution comprising chemical particles with a diameter of less than 2.5 micrometres. Previous research has shown a disproportionate exposure to air pollution among populations in the United States, particularly through exposure to PM2.5. However, little is known about the distribution of exposure amongst racially segregated communities to specific toxic chemical elements contained in PM2.5.

John Kodros and colleagues combined air pollution monitoring and American Community Survey data from 2014–2019 to assess air pollution exposure across the USA. They found that communities with a high degree of racial residential segregation are exposed to concentrations of total fine particulate matter that are two times higher and concentrations of metals from anthropogenic sources over ten times higher. The authors also suggest that these communities were exposed to a more toxic form of air pollution with a three times higher mass proportion of known toxic and carcinogenic metals — such as lead, nickel and chromium.

The authors note they found evidence that disproportionate exposure could be reduced through regulatory action and highlight that recent regulations on marine oil have reduced concentrations of vanadium and lessened the pollution risk faced by racially segregated communities. Although these regulations were not specifically designed to target vanadium, the authors argue this demonstrates the potential of regulations on anthropogenic metal emissions to reduce differences in air pollution exposure.