After decades of progress in cutting down on air pollution via regulations put in place by laws like the Clean Air Act, researchers on Thursday said that more frequent and intense wildfires are responsible for a major reversal of that advancement, with tens of millions of Americans now breathing in potentially toxic smoke each year.\r\n\r\nResearchers at Stanford University found that the number of people impacted by \u0022extreme smoke days,\u0022 during which air quality is considered unhealthy for all age groups and populations, has increased by 27 times over the past decade, with 25 million exposed to hazardous air quality on at least one day in 2020.\r\n\r\n\u0022As the globe warms, wildfires and associated air pollution are expected to increase, even under a low emissions scenario.\u0022\r\n\r\nBetween 2006 and 2010, extreme smoke days were rare, but they rapidly became far more commonplace between 2016 and 2020, with more than 1.5 million people in the U.S. regularly facing air quality deemed dangerous.\r\n\r\n\u0022There\u0026#039;s been really dramatic increases in wildfire smoke as air pollution, in some places fully reversing the impact of the Clean Air Act,\u0022 Marshall Burke, a scientist at Stanford University and co-author of the study, which was published in Environmental Science and Technology, told The Guardian. \u0022It\u0026#039;s been remarkably quick. Our air pollution regulations are not designed to deal with this. It\u0026#039;s a worrying problem.\u0022\r\n\r\nWildfire smoke has increased the level of particulate pollution in the air, according to the study. The researchers measured the presence of PM 2.5—particles which are one-thirtieth the size of a human hair—and found that wildfire smoke is responsible for an additional five micrograms of such particles in the air in parts of the western United States.\r\n\r\nAir conditions this week forced public health experts in Seattle to advise older adults, children, and people with heart or lung disease to limit their outdoor activities.\r\n\r\n\r\n\r\n\u0022The new summer on the West Coast,\u0022 wrote climate journalist Emma Pattee in an essay in The New York Times Thursday, means \u0022checking the air quality before going on a hike, getting anxious on a windy day because it means the fires are going to get worse. Scheduling camping trips, swimming lessons, and soccer camp and then canceling them as smoke interferes.\u0022\r\n\r\n\u0022For children growing up in the American West, it isn\u0026#039;t a question of what you want to do outdoors; it\u0026#039;s a question of whether you can even go outside,\u0022 she wrote.\r\n\r\nIn some parts of the U.S. West, the increase in PM 2.5 has erased progress that was made by regulating pollution that came from factories, vehicles, and other sources.\r\n\r\nThe rise in extreme smoke days has occurred as wildfires have grown in size and intensity. Six out of seven of the largest fires in California\u0026#039;s history have occurred in the last two years.\r\n\r\nThe researchers found that better forest management is part of the solution to the West\u0026#039;s worsening wildfire crisis, but that \u0022drastic cuts to greenhouse gases\u0022 are also needed, according to The Guardian.\r\n\r\nIn 2016, scientists at the University of Idaho and Columbia University found that the human-caused climate crisis and global heating were behind the doubling of forest fires over the previous three decades.\r\n\r\nExtreme heat and drought caused by the climate crisis are expected to drive a continued increase in wildfires over the next several decades, with large fires expected to become 30% more frequent by 2050 and 50% more frequent by the end of the century.\r\n\r\n\u0022As the globe warms, wildfires and associated air pollution are expected to increase, even under a low emissions scenario,\u0022\u0026nbsp;said Petteri Taalas, secretary general of the World Meteorological Organization, earlier this month. \u0022In addition to human health impacts, this will also affect ecosystems as air pollutants settle from the atmosphere to Earth\u0026#039;s surface.\u0022\r\n\r\nExposure to wildfire smoke has been linked to higher risk of heart attacks and has been blamed for 3,000 deaths in California in people over the age of 65 in 2020. In May, scientists at McGill University published research showing that people living within 31 miles of wildfires over the past decade were 10% more likely to develop brain tumors and 5% more likely to be diagnosed with lung cancer than people who lived farther away.\r\n\r\nWildfire smoke, however, can reach areas far away from its source. Last week meteorologists at The Washington Post reported that a \u0022light haze\u0022 over Washington, D.C. was \u0022indeed from the western wildfires,\u0022 and in July 2021, air quality in New York City was among the worst in the world as wildfire smoke drifted all the way across the country.