Environmental Racism: The Relationship Between Historical Residential Redlining and Current Environmental Hazards

BACKGROUND AND AIM: Communities of color in the United States (U.S.) are disproportionately exposed to environmental hazards. However, few studies have examined the relationship between historical discriminatory practices and current environmental hazard exposure, across a range of locations and hazards. In the 1930s, the Home Owners' Loan Corporation (HOLC) created community maps to indicate the level of security for real-estate investments, using grades A (good) to D (poor), a practice known as redlining. We conducted an ecological study to assess the association between historical redlining and present-day environmental hazards in 196 U.S. communities. METHODS: HOLC security maps were obtained from the University of Richmond’s Mapping Inequality Project. We used a spatial weighting method to assign a redlining score to each census tract, where at least 20% of its area was previously graded, so that higher scores represented tracts with more “D” rated neighborhoods. Data on air quality and proximity to hazardous waste and Superfund sites were obtained from the U.S. Environmental Protection Agency’s EJSCREEN. We used linear mixed effects regression models, with a random intercept for community, to assess the relationship between redlining score and current environmental hazards. Models were adjusted for percent minority population and poverty. RESULTS:Census tracts in the fourth quartile of redlining score had higher concentrations of fine particulate matter (PM₂.₅) [beta=0.05, 95% CI: 0.04, 0.06] and diesel particulate matter [beta=0.12, 95% CI: 0.10, 0.14] than census tracts in the first quartile. Census tracts in the fourth quartile were also significantly closer to hazardous waste and Superfund sites than census tracts in the first quartile. We also demonstrate a publicly-available tool to visualize this data. CONCLUSIONS:We found evidence for an association between historical government-sponsored discriminatory practices and disproportionate environmental burden in communities today. These results add to the growing literature pointing to the role of systemic racism in environmental injustice. KEYWORDS: environmental justice, environmental disparities, policy research, particulate matter, exposures