Addressing Systemic Air Pollution Inequity

Alaskan Way Viaduct Traffic Seattle, Washington

A new study finds that nearly all major sources of fine particulate air pollution disproportionately affect people of color in the United States. While it is well documented that exposure to harmful air pollution is higher for people of color than for white people, even after accounting for differences in income, it has been unclear which sources of pollution cause these disparities.

The study, PM2.5 polluters disproportionately and systemically affect people of color in the United States, published today in Science Advances finds that disparities in air pollution exposure are systemic and pervasive and not simply caused by a small number of especially polluting activities.

Researchers from the University of Illinois Urbana-Champaign, University of Washington, University of Texas at Austin, University of California at Berkeley, and University of Minnesota collaborated on the study.

Air Pollution Remains a Major Health Risk

While the air we breathe has generally become cleaner in the United States over the past few decades, disparities in air pollution exposure have remained and air pollution is still a major health risk.

Outdoor fine particulate matter (PM2.5) causes as many as 200,000 excess deaths per year according to some estimates. In addition to causing premature death, PM2.5 contributes to many other chronic health problems, including asthma and other respiratory and cardiovascular issues.

The study finds that, nationally, people of color are exposed to 14% higher levels of PM2.5 than the population average and 25% higher than white people. Industry, light-duty gasoline vehicles, construction, and heavy-duty diesel vehicles are the largest contributors to these disparities.

While smaller in overall terms, exposure to PM2.5 from residential gas combustion and commercial cooking is especially unequal—41% and 35% higher, respectively, for people of color than the population on average.

Air Pollution Inequity in the Northwest

Nationwide patterns in air pollution inequity largely hold true for the Northwest. Across the region, air pollution exposure is lower than the national average, but exposure disparities persist.

In Washington, Oregon, and Idaho, most major sources of air pollution disproportionately impact people of color. Montana is an exception, where air pollution exposure tends to be much lower overall than in other states.

Mirroring national patterns, the industry and transportation sectors are major contributors to air pollution exposure throughout the Northwest and disproportionately expose people of color in each state except Montana. Other sources of air pollution, such as residential wood burning and road dust, are uniquely large contributors to PM2.5 exposure in the Northwest.

The dashboard below compares major emissions sources by their contributions to overall exposure and racial-ethnic exposure disparity for each Northwest state and the nation as a whole.

Clean Energy Policy Must Address Air Pollution Disparities

Air pollution caused by fossil fuel use has clear and immediate health impacts, and disparities in exposure to dirty air mean that corresponding health burdens are not borne equally. An EPA-funded study showed that life expectancy of residents in the South Seattle Duwamish Valley, which has especially high levels of air pollution and numerous contaminated industrial sites, was 13 years shorter than for residents of another Seattle neighborhood just a few miles to the north.

Climate and clean energy policy will help clean the air that we breathe in the long run, but deliberate and targeted efforts to reduce air pollution in highly burdened communities are required to address past and ongoing disparities in air quality.

Climate and clean energy policies in the Northwest are beginning to include a greater focus on air pollution disparities. The Washington 2021 State Energy Strategy called for embedding equity in the design of clean energy policies and programs and incorporating a commitment to correcting past and ongoing environmental harms.

Recent climate and clean energy legislation in Washington included provisions that specifically address air pollution disparities:

  • The Clean Energy Transformation Act, Washington’s Clean Energy Standard, instructed the Washington State Department of Health to use cumulative impact analysis to designate communities highly impacted by fossil fuel pollution. The law then requires electric utilities to assess in their planning processes how their decarbonization efforts will reduce health burdens for those communities.
  • The Clean Fuels Program, detailed in HB1091 and awaiting Governor Inslee's signature, is designed to reduce the carbon intensity of transportation fuels over time. Replacing gasoline and diesel with electricity and biofuels would not only lead to lower greenhouse gas emissions, but it would also reduce emissions of local air pollutants that harm human health.
  • To prioritize the areas that need cleaner air most, the Clean Fuels Program requires 30% of revenue earned by electric utilities from selling compliance credits to be invested in transportation electrification projects that benefit communities with higher levels of air pollution.
  • The recently passed Climate Commitment Act, which is headed to Governor Inslee’s desk, will establish a cap-and-invest program in Washington to drive down greenhouse gas emissions in line with the state’s existing statutory limits. The bill directly acknowledges that carbon policies alone may not do enough to mitigate existing environmental health disparities and deliver direct benefits to highly burdened communities.

Some of these learnings stem from California’s experience with carbon pricing, where its cap-and-trade program has been criticized for failing to reduce pollution for fenceline communities and communities of color. One study showed that neighborhoods where pollutant emissions increased from nearby facilities participating in the cap-and-trade program had higher proportions of people of color than neighborhoods that saw decreased emissions.

The Climate Commitment Act has numerous provisions aimed at mitigating air pollution disparities in addition to limiting greenhouse gas emissions:

  • The Washington State Department of Ecology will be required to deploy air pollution monitors in overburdened communities to determine the greatest contributors to local air pollution and track air pollution reductions. If reductions are not being achieved, the Department of Ecology will be able to place additional requirements on emitters.
  • At least 35% of investments of revenues generated from allowances must provide direct and meaningful benefits to overburdened communities, including through reductions in disproportionate, cumulative risk from environmental burdens and through expenditures from a dedicated air quality and health disparities improvement account. Progress toward meeting environmental justice and environmental health goals achieved through program investments will be reported to a newly created environmental justice council.
  • The limit on offsets, which is set at 5% of an emitter’s obligation in the first compliance period, can be tightened if the Department of Health and the environmental justice council determine that an emitter is contributing substantively to cumulative air pollution burden in an overburdened community.


PM2.5 polluters disproportionately and systemically affect people of color in the United States bolsters the scientific evidence of systemic air pollution inequities for communities of color in the United States and the Northwest. These findings underscore the need to embed environmental justice priorities and targeted actions to reduce air pollution disparities into climate and clean energy policy.

David Paolella is a co-author of this study.

David Paolella

Research and Policy Analyst
David Paolella is a Research and Policy Analyst at the Clean Energy Transition Institute. He focuses on bringing together science, technology, and economics to advance practical climate solutions that promote economic opportunity and environmental justice. As a Yakima, Washington native, David is passionate about helping the Northwest forge a path to deep decarbonization that the rest of the country can follow.
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