Communities of color in the U.S. have long reported health problems from heavy exposure to polluted air. A new study erases a great deal of any doubt that might have existed about racial and ethnic disparities in exposure to air pollution emitted from a variety of sources. “What we found instead is that it's actually almost all of the source types of air pollution that are causing the disparity. To estimate the fine particle pollution sources’ impact on racial and ethnic groups, the team started with 2014 data from the Environmental Protection Agency’s National Emissions Inventory. Tessum says the new findings point to a problem inherent in clean-air policies that have successfully reduced air pollution nationwide in recent decades: such strategies will not eliminate the extra air pollution and associated health risks experienced by people of color.