Various studies show that people of color are disproportionately exposed to air pollution in the United States. However, it is not known whether this uneven exposure is mainly due to a few types of emission sources or if the causes are more systemic. A new study that models people’s exposure to air pollution – resolved by race-ethnicity and income level – shows that disparities in exposure between people of color and white people are due to almost everyone, rather only a few types of emission sources.
The study by Christopher Tessum, professor of civil and environmental engineering at the University of Illinois Urbana Champaign, is published in the journal Scientific progress.
“Community organizations have been experimenting with and campaigning against environmental injustice for decades,” Tessum said. “Our study contributes to an already large body of evidence with the new finding that there is not a single source of air pollution, or a small number of sources, that explains this disparity. Instead, the disparity is caused by almost all sources. “
The team used an air quality model to analyze Environmental Protection Agency data for more than 5,000 types of emission sources, including industry, agriculture, electric utilities coal, light and heavy gasoline vehicles, diesel vehicles, off-road vehicles and equipment, construction. , residential sources, road dust and other small sources of miscellaneous emissions. Each type of source studied contributes to air pollution by fine particles, defined as particles 2.5 microns 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 the numbers from the US Census Bureau residential population to identify differences in exposure by race-ethnicity and income.
The researchers found that for the average total U.S. population in 2014, exposures to fine particle air pollution from most types of sources are higher than average for people of color and below. the average for whites. The data indicates that whites are exposed to below-average concentrations from types of emission sources that, when combined, cause 60% of their total exposure, the study reports. Conversely, people of color experience above average exposures from types of sources that when combined account for 75% of their total exposure. This disparity exists at the country, state and city level and for people at all income levels.
“We find that almost all sectors of emission cause disproportionate exposures for people of color on average,” said co-author Julian Marshall, professor of civil and environmental engineering at the University of Washington. “The inequalities we report are the result of systemic racism: over time people of color and pollution have been brought together, not just in a few instances, but for almost every type of program.”
Researchers have found that air pollution disparities stem from a more systemic set of causes than previously understood.
“We have been struck by how these systemic disparities exist for people of color not only in certain neighborhoods but at all spatial scales in the United States,” said co-author Joshua Apte, professor of civil and environmental engineering. at the University of California at Berkeley. . “The problem exists in urban and rural areas, in many distinct parts of the United States, and for people living in nearly every city in the United States.”
“This new study adds context to our previous work, which has shown that a disproportionate consumption of goods and services – which is an underlying cause of pollution – exacerbates the exposure of people of color to pollution from the world. air, ”said co-author Jason Hill. , professor of bioproducts and biosystems engineering at the University of Minnesota.
The study results come with caveats, the researchers said. Emissions data, air quality modeling, and population count all contain previously quantified uncertainty. However, because the team’s results are consistent across states, urban and rural areas, and concentration levels, they are unlikely to be a model artifact or measurement bias. This study focuses on the concentrations of outdoor air pollution in places of residence and does not take into account the variability in mobility, access to health care and basic mortality and morbidity rates, among other factors.
“Some assume that when there is a systematic racial and ethnic disparity, like the one we see here, the underlying cause is a difference in income,” Tessum said. “Because the data shows that the disparity cuts across all income levels, our study reinforces previous findings that race, rather than income, is what really causes disparities in pollution exposure. the air.”
The researchers hope these findings will highlight potential opportunities to address this persistent environmental inequality.