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Higher levels of toxic-metal air pollution seen in racially segregated communities

Individuals living in racially segregated areas are more likely to breathe in toxic-metal air pollution than those residing in more integrated areas.

Story at a glance


  • Researchers assessed concentrations of metals like lead, cadmium and copper in air pollution.

  • Industrial regions in the Midwest and shipping ports in coastal cities tended to be more segregated and have higher levels of the pollutants.

  • Targeted regulations on man-made emissions could help mitigate these disparities.

Residents of the most racially segregated communities tend to breathe in higher concentrations of toxic-metal air pollution compared with residents in more integrated areas.

That’s according to new research from Colorado State University that assessed air levels of toxic-metals like lead, cadmium and nickel in different communities throughout the country. Levels were recorded between 2010 and 2019.

“While concentrations of total fine particulate matter are two times higher in racially segregated communities, concentrations of metals from anthropogenic sources are nearly ten times higher,” authors wrote, adding these pollutants are toxic and can cause cancer. 

Results showed industrial regions in the Midwest and shipping ports in coastal cities tended to have higher concentrations of human-emitted metal pollutants like lead. These areas also had high degrees of racial segregation. 


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For decades, people of color have been exposed to higher levels of air pollution than their white counterparts. The systematic separation of racial or ethnic groups in separate geographical areas has also been linked with higher risks of infant and all-cause mortality, cardiovascular disease, and pregnancy complications.

These health disparities are largely due to systemic racism, including historic redlining. In the 1930s, laws permitted discriminatory loan distribution to residents based on their neighborhood’s desirablilty. This practice was outlawed in 1968 but continues to perpetuate present-day disparities, as it forced populations of color to live closer to sources of pollution. 

Researchers assessed the toxic metal components of fine particulate matter in both racially segregated and racially integrated areas. A total of nine metals were studied and separated into two groups: those resulting from human activity and those from natural sources.

Overall, results showed different areas were exposed to different types of particles and that emission sources play a role in exposure rates. 

“Anthropogenically emitted particulate metal concentrations are on average 30–75 percent higher in highly segregated counties compared to moderately segregated counties and a factor of 5-20 times higher in highly segregated counties compared to well-integrated counties,” authors wrote. 

Humans can emit these metals through industrial processes, vehicle engines or heavy fuel combustion.

Although the study only compared racial segregation between non-Hispanic Black and non-Hispanic white residents, further analyses showed similar, though not as strong, associations between degrees of segregation for Hispanic, Asian and Native American populations and their white counterparts.

Emission reductions targeting man-made pollutants could help mitigate the racial disparities uncovered by the study, researchers wrote.

“The good news is that sweeping environmental cleanups, like the establishment of national clean-fuel standards, not only reduce air pollution nationwide, but also serve to reduce the pollution exposure disparities we see in many segregated communities,” said study co-author John Kodros in a release. 

Published on Nov 02,2022