The American Lung Association report finds that climate events are causing more people in the U.S. to breathe toxic air even as other pollution falls.

Air pollution levels keep getting worse for more people in the US, according to a new report, and experts say the Trump administration’s proposed deregulation plans will make it even harder for people to get clean air.

“State of the Air” uses letter grades to measure unhealthy levels of ground-level ozone air pollution (also known as smog), and year-round and short-term spikes in particle pollution (also known as soot) over a three-year period. The 2025 report looks at the latest quality-assured air quality data, which was collected from 2021 to 2023.