Highways crossing historically redlined areas likely cause disparities in air pollution today

As part of the New Deal, several government programs were created to increase homeownership through mortgages and loans. However, neighborhoods with primarily black or immigrant communities were often deemed “unsafe” for repayment under the discriminatory “redlining” practice that restricted lending.

Today, these same areas are exposed to more air pollution than other urban neighborhoods and, according to a study published in Environmental science and technologythe cause could be related to nearby highways or industrial parks.

Between the 1930s and the late 1960s, groups such as the Federal Housing Administration and the Home Owner’s Loan Corporation (HOLC) worked to insure the loans, but they were selective about which neighborhoods would receive this funding. Areas were graded from “A” (least risky) to “D,” which was considered the most risky, and coded red.

These red-marked neighborhoods were often home to black or immigrant communities whose residents were systematically denied mortgages or loans because of the maps. During the same period, many of these communities were crossed by interstate highways, isolating them or completely demolishing them.

Recently, researchers have shown that areas historically redlined have higher levels of air pollution than those with higher ratings, and that similar disparities affect many U.S. cities. Denver is one of these cities, where Joost de Gouw and his colleagues wanted to investigate the origin of pollution. differences.

The team gathered satellite and computer modeling data on nitrogen dioxide (NO₂) and fine particles suspended in the air (PM_2.5), both of which can be harmful if inhaled. Combining demographic data from the 2020 census and historical maps compiled by HOLC, researchers found that neighborhoods rated “D” had 13% higher NO levels.₂ than areas labeled “A”.

Across Denver, neighborhoods where the majority of residents identified as non-Hispanic White and Asian or Asian American were exposed to less NO.₂ and MP_2.5 as areas where there are groups identifying primarily as American Indian and Alaska Native, as well as Hispanic or Latino.

The researchers also studied possible sources of NO₂ and MP_2.5 emissions affecting the areas previously highlighted. They found that diesel vehicles emitted about half the nitrogen oxides of road vehicles, while other pollutants, such as benzene, were emitted from other point sources, including nearby petrochemical refineries.

Many of Denver’s highways and major industrial areas, including Commerce City, are surrounded by diverse communities that generally contain fewer people identifying as non-Hispanic white, even though this group makes up the majority of the city’s population. The researchers say this work helps identify areas that could be most improved by sanitation programs such as clean technology incentives.