Environmental Justice and Air Pollution

The environmental justice movement traces its modern origin to a 1982 protest in Warren County, North Carolina, where mostly Black residents blocked trucks dumping PCB-contaminated soil. Forty years later, environmental justice research has accumulated overwhelming evidence that air pollution in the United States is not distributed evenly, and that the unevenness tracks race more closely than income.

Background

Environmental justice (EJ) research asks two related questions. Who is exposed to higher levels of pollution? And who bears the resulting health burden? Both have been studied at increasingly fine spatial scales as exposure modeling has improved. The EPA's EJScreen tool, launched publicly in 2015, made it easier to pull census-tract-level pollution and demographic data together, accelerating the research.

What the studies found

Race tracks PM2.5 exposure independent of income. Christopher Tessum, Julian Marshall, and colleagues published in Science Advances in 2021 the most-cited national analysis. They mapped emissions from more than 5,000 source categories to neighborhood-level PM2.5 exposure. White Americans were exposed to lower-than-average PM2.5 from emission sources causing about 60 percent of total exposure. Black, Latino, and Asian Americans experienced higher-than-average exposure from sources causing 75 percent of total exposure. The pattern held at every income level.

Disparities are growing, not shrinking. A 2024 Environmental Health Perspectives study by Jbaily, Dominici, and colleagues at Harvard found that while overall U.S. PM2.5 mortality has fallen since 2000, the gap in PM2.5-attributable deaths between Black and White Americans has widened in relative terms. Black communities now experience a larger share of remaining PM2.5 deaths than they did 20 years ago.

Redlining and present-day pollution. Multiple studies have linked the federal Home Owners' Loan Corporation (HOLC) maps drawn in the 1930s, which graded neighborhoods A through D and effectively denied mortgages to D-graded (often majority-Black) neighborhoods, to higher present-day pollution. Lane et al. (Environmental Science and Technology Letters 2022) found NO2 levels in formerly D-graded neighborhoods were on average 56 percent higher than in formerly A-graded neighborhoods in the same cities, and PM2.5 levels were 7 percent higher. A 2024 follow-up by the same group using EJScreen confirmed the cumulative environmental burden gradient by HOLC grade.

Near-road exposure. Joshua Apte (UC Berkeley) and colleagues used Google Street View cars equipped with mobile monitors to map block-by-block NO2 and black carbon in Oakland. The maps showed twofold to sixfold differences between blocks just hundreds of meters apart, with the highest pollution near port and freight infrastructure that disproportionately borders Black and Latino neighborhoods.

Why it matters

The Biden administration's Justice40 initiative directs 40 percent of climate and clean-air investment benefits to disadvantaged communities. EPA's 2024 PM2.5 standard explicitly cites environmental justice in its rationale. State-level cumulative impact laws (New Jersey 2020, New York 2023) require regulators to consider existing pollution burden when permitting new sources in already-loaded neighborhoods.

The disparities also explain a chunk of population health gaps. Studies estimate PM2.5 exposure differences account for a meaningful fraction of Black-White cardiovascular mortality differences in U.S. cities, on top of differences in access to care and chronic stress.

Open questions

Researchers still debate how much of present-day disparity is driven by historical siting decisions (locked-in infrastructure) versus ongoing permitting and zoning. Whether EJ-targeted cleanup yields measurably faster health improvement in burdened communities is an active question being studied through natural experiments like California's AB 617 community air monitoring program. Indoor air quality disparities (older housing, gas stoves, less HEPA filtration) are likely to widen the picture further as data improves.

Sources

• PM2.5 polluters disproportionately and systemically affect people of color in the United States (Tessum et al., Science Advances 2021)
• Increasing Racial and Ethnic Disparities in Ambient Air Pollution-Attributable Morbidity and Mortality in the United States (Jbaily et al., EHP 2024)
• Historical Redlining Is Associated with Present-Day Air Pollution Disparities in U.S. Cities (Lane et al., ES&T Letters 2022)
• Historical Redlining and Cumulative Environmental Impacts across the United States (ES&T Letters 2024)
• High-resolution air pollution mapping with Google Street View cars (Apte et al., ES&T 2017)
• EPA EJScreen environmental justice screening tool
• The Disparities in PM2.5 Exposure in the United States (Colmer et al., Science 2020)