People of color, and black people in particular, are much more likely to be exposed to air pollution, scientists at the Environmental Protection Agency found.

Though the findings were published by scientists employed by the EPA on Thursday, the agency is unlikely to take any action to help. Since Administrator Scott Pruitt took the helm, the agency has scaled back enforcement of environmental regulations and dismissed scientists from its advisory board. So far, Pruitt has let go half of the scientists who had served under the previous administration, choosing to appoint oil and gas reps, people from state regulatory agencies, and one scientist who thinks “modern air is a little too clean for optimum health.”

The study, published by a group of researchers at the agency, found that particulate matter in air — specifically, floating particles that are less than 2.5 microns in diameter and emitted from everything from cars to refineries — affects the poor and people of color more than it does the white and affluent in all but four states. The matter, which can make the air hazy, is regulated by the EPA because it’s known to cause a range of negative health effects, like aggravating asthma and causing heart attacks.

And the numbers might get worse: In January, the agency announced it is revising an Obama-era haze rule. It may allowing states more leniency on particulate matter regulation.

“What the study says to me is that we need to think about the role not only poverty plays, but also that race plays, in how we think about people's health,” said Malo Hutson, director of the Urban Community and Health Equity Lab at Columbia University, who was not involved with the study. “This kind of study, which looks at particulate pollution nationally, is particularly useful.”

Drawing on data from the EPA’s National Emissions Inventory, which collects local data on air pollution emissions, the researchers cross-referenced the emissions info with census data to determine the populations that are most exposed to pollution.

They found that, while most people in the U.S. live near sources of particulate matter pollution, people who live below the poverty line were exposed to 1.35 times more particulate matter than those who live above it. People of color are exposed to 1.2 times more particulate matter pollution, and black people are at particular risk, exposed, on average, to 1.54 times more particulate matter pollution than the general population.

The reason: Poor people and people of color are driven to live in areas that are seen as undesirable, due to their proximity to pollution. And once there, the study notes, racial and economic discrimination keeps them from being able to effect change and reduce air pollution where they live.