While the newer study only examined air pollution, its findings bolster the earlier report’s conclusions. Plus, interstate highways — identified as a main driver of risk in the air pollution study — have their own extensive history as deliberate tools for redlining that, in many cities, targeted minority neighborhoods and promoted segregation.

“In general, there’s just an unequal distribution of environmental hazards across the St. Louis area,” said Ekenga. “You see these sorts of associations across the U.S. … but the magnitude of the strength of the association we saw here was very surprising to me.”

Maps accompanying the study show the census tracts with the greatest likelihood of exposure to cancerous air toxins. While many of the areas are in or near the core of the St. Louis metro area — including some affluent communities that line Highway 40 (Interstate 64) — they also include parts of the Metro East, and a sizable swath of north St. Louis County, near interstates 70 and 270.

Ekenga hopes to look into the matter more closely, moving forward. Because the published study relied on modeled concentrations of air pollutants, she would like to gather localized data from certain high-risk areas firsthand.