Heat and Fire Making Pollution Worse Across Much of the U.S.

By several measures, air pollution is getting worse in the U.S., a trend due in large part to more severe heat and wildfires, according to a new report.

Parts of the country that were not previously burdened by smog have seen pollution worsen in recent years as heat and sunlight transform car exhaust into ozone pollution. “Warmer temperatures driven by climate change make ozone more likely to form and harder to clean up,” according to the new report, from the American Lung Association. The group found that, from 2021 to 2023, five times as many counties saw ozone pollution worsen as saw it improve.

Wildfires were also a factor in ozone pollution, and in parts of the country led to spikes in particulate pollution. Last year, the number of days in which counties recorded “unhealthy” and “very unhealthy” levels of particulates reached their highest level in at least two decades. The report found that a growing number of Americans are facing dangerous levels of particulate pollution, a trend “that not only is continuing but worsening as a consequence of climate change.”

Both ozone and particulate pollution can aggravate asthma, raise the risk of a heart attack and stroke, and lead to an early death. And people of color, particularly Hispanic Americans, are far more likely than their white counterparts to face high levels of these pollutants, according to the report. The findings come as the Trump administration seeks to weaken rules on air pollution.

“Even as more people are breathing unhealthy air, the federal staff, programs, and policies that are supposed to be cleaning up pollution are facing rollbacks, restructuring, and funding challenges,” said Harold Wimmer, head of the American Lung Association. “Efforts to slash staff, funding and programs at EPA are leaving families even more vulnerable to harmful air pollution.”

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