Science  /  Study

How Air Pollution Across America Reflects Racist Policy From the 1930s

A new study shows how redlining, a Depression-era housing policy, contributed to inequalities that persist decades later in U.S. cities.

Urban neighborhoods that were redlined by federal officials in the 1930s tended to have higher levels of harmful air pollution eight decades later, a new study has found, adding to a body of evidence that reveals how racist policies in the past have contributed to inequalities across the United States today.

In the wake of the Great Depression, when the federal government graded neighborhoods in hundreds of cities for real estate investment, Black and immigrant areas were typically outlined in red on maps to denote risky places to lend. Racial discrimination in housing was outlawed in 1968. But the redlining maps entrenched discriminatory practices whose effects reverberate nearly a century later.

To this day, historically redlined neighborhoods are more likely to have high populations of Black, Latino and Asian residents than areas that were favorably assessed at the time.

California’s East Bay is a clear example.

The neighborhoods within Berkeley and Oakland that were redlined sit on lower-lying land, closer to industry and bisected by major highways. People in those areas experience levels of nitrogen dioxide that are twice as high as in the areas that federal surveyors in the 1930s designated as “best,” or most favored for investment, according to the new pollution study.

Margaret Gordon has had decades of experience with these inequalities in West Oakland, a historically redlined neighborhood. Many children there suffer from asthma related to traffic and industrial pollution. Residents have long struggled to fend off development projects that make the air even worse.

“Those people don’t have the voting capacity, or the elected officials, or the money to hire the lawyers, to fight this,” said Ms. Gordon, co-director of the West Oakland Environmental Indicators Project, an advocacy group.

The new study’s lead author, Haley M. Lane, said she was surprised to find that the differences in air pollution exposure between redlined and better-rated districts were even larger than the well-documented disparities in exposure between people of color and white Americans.

“At the same time, there are so many other effects that are creating these disparities, and these delineations by redlining are just one,” said Ms. Lane, a graduate student in civil and environmental engineering at the University of California, Berkeley.

Researchers have unearthed patterns of all kinds ever since scholars digitized a large collection of redlining maps in 2016.

With less green space and more paved surfaces to absorb and radiate heat, historically redlined neighborhoods are 5 degrees hotter in summer, on average, than other areas. A 2019 study of eight California cities found that residents of redlined neighborhoods were twice as likely to visit emergency rooms for asthma.