Historical Redlining Is Associated with Present-Day Air Pollution Disparities in US Cities

Communities of color in the United States are systematically exposed to higher levels of air pollution. We explore here how redlining, a discriminatory mortgage appraisal practice from the 1930s by the federal Home Owners' Loan Corporation (HOLC), relates to present-day intraurban air pollution disparities in 202 U.S. cities. In each city, we integrated three sources of data: (1) detailed HOLC security maps of investment risk grades [A (best), B, C, and D (hazardous, i.e., redlined)], (2) year-2010 estimates of NO 2 and PM2.5 air pollution levels, and (3) demographic information from the 2010 U.S. census. We find that pollution levels have a consistent and nearly monotonic association with HOLC grade, with especially pronounced (>50%) increments in NO2 levels between the most grade A) and least (grade D) preferentially graded neighborhoods. On a national basis, intraurban disparities for NO2 and PM2.5 are substantially larger by historical HOLC grade than they are by race and ethnicity. However, within each HOLC grade, racial and ethnic air pollution exposure disparities persist, indicating that redlining was only one of the many racially discriminatory policies that impacted communities. Our findings illustrate how redlining, a nearly 80-year-old racially discriminatory policy, continues to shape systemic environmental exposure disparities in the United States.

Automated summary

Communities of color in the United States are disproportionately exposed to higher levels of air pollution, and this study shows a connection between this disparity and the historical redlining policy. The research finds that air pollution levels have a consistent association with redlining grade, and the disparities in NO2 and PM2.5 pollution levels based on redlining grade are larger than those based on race and ethnicity.