At the height of the Great Depression, when home foreclosures in the United States soared to 1,000 per day, the federal government adopted programs to keep people in their homes and make mortgages more affordable — just not for everybody. To determine who would get assistance, the Home Owners’ Loan Corporation, created as part of President Franklin D. Roosevelt’s New Deal, mapped out cities across the country in the 1930s. Appraisers ranked neighborhoods all over the country on a scale from Grade A to Grade D, drawing green lines around the neighborhoods deemed most desirable and red lines around the “hazardous” ones — essentially a code word for where ethnic minorities and especially Black people lived.

Even though “redlining” was banned in 1968, its legacy is still creating problems today, since urban planners saddled these neighborhoods with polluting industrial plants, airports, and highways. Historically redlined neighborhoods have fewer trees than richer neighborhoods and suffer more from air pollution and extreme heat. And according to a recent study published in Nature Ecology & Evolution, they are also subject to more noise pollution, often at volumes that pose risks to human health.

Researchers at Colorado State University, along with experts in New Mexico, New Hampshire, and the United Kingdom, analyzed how exposure to transportation noise aligned with maps of historically redlined neighborhoods, looking at the consequences for human health and urban wildlife. They found that the maximum noise levels in neighborhoods coded as Grade D by the Home Owners’ Loan Corporation back in the 1930s were 10 times higher than in Grade A neighborhoods, in terms of sound intensity.

Read the full article about noise pollution by Kate Yoder at Grist.