Decades of federal housing discrimination did not only depress home values, lower job opportunities and spur poverty in communities deemed undesirable because of race. It's why 45 million Americans are breathing dirtier air today, according to a landmark study released Wednesday. The analysis, published in the journal Environmental Science and Technology Letters, found that, compared with White people, Black and Latino Americans live with more smog and fine particulate matter from cars, trucks, buses, coal plants and other nearby industrial sources in areas that were redlined. Those pollutants inflame human airways, reduce lung function, trigger asthma attacks and can damage the heart and cause strokes. "Of course, we've known about redlining and its other unequal impacts, but air pollution is one of the most important environmental health issues in the U.S.," said Joshua Apte, a co-author of the study and an assistant professor in the School of Public Health at the University of California at Berkeley. "If you just look at the number of people that get killed by air pollution, it's arguably the most important environmental health issue in the country," Apte said.