More than 133.9 million people are exposed to unhealthy levels of air pollution, up from 125 million people, according to 2014-16 data from the American Lung Association's State of the Air 2018 report.
Here are five report insights.
1. More than four in 10 Americans (41 percent) reside in counties with unhealthful levels of either ozone or particle pollution.
2. Due to tools in the Clean Air Act, the number of people exposed to unhealthful air is still significantly less than the 166 million in the years covered in the 2016 report (2012-14).
3. Over 7.7 million people (2.4 percent) live in 10 counties with unhealthful levels of ozone, short-term and year-round particle pollution.
4. Los Angeles remains the worst city for ozone pollution, Fairbanks, Ark., had the highest levels of year-round particle pollution and Bakersfield, Calif., had the worst short-term particle pollution.
5. The report indicates actions taken under the Clean Air Act are cleaning up pollution across the U.S., with numerous cities reporting decreased levels of year-round particle pollution. Additionally, a number of cities reached or remained close to their cleanest years ever.