Air pollution exposure disparities among people of color and white people are driven by nearly all, rather than only a few, emission source types, a new study shows.

Previous studies have shown that people of color are disproportionately exposed to air pollution in the United States. However, it was unclear whether this unequal exposure is due mainly to a few types of emission sources or whether the causes are more systemic.

“Our study reinforces previous findings that race, rather than income, is what truly drives air pollution-exposure disparities.”

The new study in Science Advances modeled peoples’ exposure to air pollution based on race/ethnicity and income level.

“We find that nearly all emission sectors cause disproportionate exposures for people of color on average,” says coauthor Julian Marshall, a professor of civil and environmental engineering at the University of Washington. “The inequities we report are a result of systemic racism: Over time, people of color and pollution have been pushed together, not just in a few cases but for nearly all types of emissions.”

Patterns in air pollution exposure

The team used an air quality model to analyze Environmental Protection Agency data for more than 5,000 emission source types, including industry, agriculture, coal electric utilities, many types of vehicles and equipment, construction, and other miscellaneous small emissions sources. Each source type studied contributes to fine particle air pollution, defined as particles being 2.5 micrometers or less in diameter, the study reports.

To identify patterns of air pollution exposure associated with race/ethnicity and income, the researchers combined the spatial air pollution patterns predicted in their air quality model with residential population counts from the US Census Bureau.

For the 2014 US total population average, fine particulate air pollution exposures from the majority of source types are higher than average for people of color and lower than average for white people. The results indicate that white people are exposed to lower-than-average concentrations from emissions source types that, when combined, cause 60% of their total exposure, the study reports.

Conversely, people of color experience greater-than-average exposures from source types that, when combined, cause 75% of their total exposure. This disparity exists at the country, state, and city level and for people within all income levels.

“Community organizations have been experiencing and advocating against environmental injustice for decades,” says corresponding author Christopher Tessum, a civil and environmental engineering professor at the University of Illinois Urbana Champaign.

“Our study contributes to an already extensive body of evidence with the new finding that there is no single air pollution source, or a small number of sources, that account for this disparity. Instead, the disparity is caused by almost all of the sources.”

Race, not income

The researchers found that air pollution disparities arise from a more systemic set of causes than previously understood.

“We were struck by how these systemic disparities exist for people of color not only in certain neighborhoods but at every spatial scale in the US,” says coauthor Joshua Apte, a professor of civil and environmental engineering at the University of California, Berkeley. “The problem exists within urban and rural areas, many distinct US regions, and for people living within almost all American cities.”

The study results come with caveats, the researchers say. For example, the study focuses on outdoor air pollution concentrations in places where people reside and does not account for variability in mobility, access to health care, and baseline mortality and morbidity rates, among other factors.

“This new study adds context to our previous work, which showed that a disproportionate consumption of goods and services—which is an underlying cause of pollution—compounds the exposure of people of color to air pollution,” says coauthor Jason Hill, a professor of bioproducts and biosystems engineering at the University of Minnesota.

The researchers hope these findings will highlight potential opportunities for addressing this persistent environmental inequity.

“Some assume that when there is a systematic racial-ethnic disparity, such as the one we see here, that the underlying cause is a difference in income,” Tessum says. “Because the data shows that the disparity cross-cuts all income levels, our study reinforces previous findings that race, rather than income, is what truly drives air pollution-exposure disparities.”

Additional coauthors are from the University of Texas at Austin and the University of Washington. The EPA provided financial support for this study through the Center for Air, Climate, and Energy Solutions (CACES).

Source: University of Washington

Related

Air pollution shortens life expectancy by 2 years

Indigenous peoples bear the brunt of pollution

White people create more air pollution, but breathe in less

Black and Hispanic Americans are exposed to higher amounts of air pollution that non-Hispanic white Americans generate, according to new research.

Poor air quality is the largest environmental health risk in the United States. Fine particulate matter pollution is responsible for more than 100,000 deaths each year from heart attacks, strokes, lung cancer, and other diseases.

But not everyone is equally exposed to poor air quality—nor are all people equally responsible for generating it.

The new finding, which quantifies for the first time the racial gap between who generates air pollution and who breathes it, appears in the Proceedings of the National Academy of Sciences.

“Similar to previous studies, we show that racial-ethnic minorities are exposed to more pollution on average than non-Hispanic whites,” says first author Christopher Tessum, a research scientist in the University of Washington’s civil and environmental engineering department and a recent University of Minnesota graduate.

On average, non-Hispanic white Americans spend more money on pollution-intensive goods and services, which means they generate more pollution than other groups

“What is new is that we find that those differences do not occur because minorities on average cause more pollution than whites—in fact, the opposite is true.”

The team compared what people spend their money on—like buying groceries or gas or getting clothes dry-cleaned—to the pollution these activities generate. Then the researchers overlaid these results on a map of where people live to see if there was the difference between the pollution that specific racial-ethnic groups generate and what they experience.

“Someone had to make the pen you bought at the store,” says coauthor Julian Marshall, a professor of civil and environmental engineering. “We wanted to look at where the pollution associated with making that pen is located. Is it close to where people live? And who lives there?”

The team found that on average, non-Hispanic white Americans spend more money on pollution-intensive goods and services, which means they generate more pollution than other groups. But white Americans also experience a “pollution advantage” in that they face exposure to approximately 17 percent less pollution than they generate.

On average, black Americans experience about 56 percent more pollution than they generate. For Hispanics, it is slightly higher: 63 percent.

At the same time, black and Hispanic populations bear a “pollution burden.” On average, black Americans experience about 56 percent more pollution than they generate. For Hispanics, it is slightly higher: 63 percent.

Longstanding societal trends, such as income inequality, may influence these disparities. Also, racial patterns in where people live often reflect segregation or other conditions from decades earlier. Black and Hispanic Americans are more likely to live in locations with higher concentrations of pollution compared to white Americans, which means they have increased average daily exposure to it.

In general, the US has made strides to reduce air pollution across the country: Average exposure to particulate pollution declined approximately 50 percent between 2003 and 2015. But pollution inequity remained high over that same period.

“Our work is at the intersection of many important and timely topics such as race, inequality, affluence, environmental justice, and environmental regulation,” says corresponding author Jason Hill, an associate professor of bioproducts and biosystems engineering at the University of Minnesota.

The team hopes this pollution-inequity metric can provide a simple and intuitive way for policymakers and the public to see the disparity between the pollution that population groups generate and their pollution exposure.

“The approach we establish in this study could be extended to other pollutants, locations, and groupings of people,” Marshall says. “When it comes to determining who causes air pollution—and who breathes that pollution—this research is just the beginning.”

Additional coauthors are from the University of Texas at Austin, the University of New Mexico, Carnegie Mellon University, Lumina Decision Systems, the University of Washington, and the University of Minnesota.

The US Environmental Protection Agency, the US Department of Energy, the US Department of Agriculture, and the University of Minnesota Institute on the Environment funded the study.

Source: University of Washington

Related

Tiny particles in air pollution may damage fetal hearts

How air pollution exposure may lead to autism

Severe air pollution cuts productivity at work