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Racial segregation linked with more toxic air pollution

Non-Hispanic Black Americans living in the most segregated neighborhoods are exposed to particulate pollution that contains a higher percentage of toxic and carcinogenic metals

by Katherine Bourzac
November 1, 2022


Color-coded map assigns different risk levels for mortgage loaners in the city of Philadelphia. Areas deemed "hazardous" are colored in light pinkish red. Areas colored in blue are marked "still desirable." Yellow is "declining."
Credit: Wikimedia Commons
This 1936 Home Owners' Loan Corporation of Philadelphia map, an example of redlining, categorizes areas of the city as more or less risky for mortgage loans. Racial segregation in the US persists and is linked to air pollution exposure disparities.

Exposure to fine particulate air pollution (PM2.5) is a leading cause of death and disease around the world. In the US, race and ethnicity are associated with disparities in people’s exposures. Now, researchers have shown that these disparities are tied not just to demographic differences but to racial segregation. The study finds that non-Hispanic Black people living in the most highly segregated parts of the country are not only exposed to more total air pollution than non-Hispanic White people in nearby neighborhoods, the pollution they breathe contains 10 times the concentrations of toxic and carcinogenic metals, including lead (Nat. Commun. 2022, DOI: 10.1038/s41467-022-33372-z).

Due to a history of racist laws and housing development practices, many US cities are segregated. Highways and factories that produce air pollution are more likely to be located in predominantly Black neighborhoods to this day, says Colorado State University engineer John K. Kodros. Kodros and his team drew on census data to rank US neighborhoods’ segregation levels by comparing the percentage of non-Hispanic Black people in a neighborhood with that of their city as a whole. For example, if 30% of a neighborhood’s population is Black in a city that’s 30% Black, segregation is low, Kodros says. If that city’s population is 1% Black, segregation in that neighborhood is high.

The group drew on PM2.5 composition data from more than 200 air quality monitors operated by the US Environmental Protection Agency. The researchers focused on levels of carcinogenic trace metals such as Ni, Cr, and V, and neurotoxic metals such as Pb, Mn, and Cu. The study’s main limitation, Kodros says, is the relative sparseness of these specialized monitors. The research team plans to expand their study by installing more of them.



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