Air pollution is increasing over a wide swath of the U.S. because of record wildfires

The consequences of America’s swelling wildfire problem are traveling well beyond blackened, ashy forests. They're now tainting the air in cities and towns over vast regions of the western U.S.  Since the mid-1980s, fine bits of air pollution that have been repeatedly linked to heart and lung diseases have diminished in a good portion of the United States — except in an expansive zone of the western part of the country.  In this region, which extends north from Utah to Montana and west from Oregon to Wyoming, the most polluted days — when the air quality is at its most harmful — are getting even worse.