A new study released Wednesday shows things aren't getting better.
On a brighter note, the 2019 report found year-round particle pollution levels in Denver are lower than the 2018 report.
Climate change-fueled forest fires and weather patterns contributed to the worsening air quality in the United States, the report stated.
The American Lung Association (ALA) just gave Indianapolis an "F" grade when it comes to ozone pollution!
These moves have seemed to cause some alarm at the American Lung Association, which insists that 'the Clean Air Act must remain intact and enforced to enable the nation to continue to protect all Americans from the dangers of air pollution, ' the association said in its report.
Eugene-Springfield came in at No. 19 for short-term particle pollution, Bend-Prineville at No. 22 and Portland-Vancouver-Salem at No. 23.More news: Tesla updates Model S, X: 370-mi range, faster charging, adaptive suspension
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The report said that the Fresno-Madera-Hanford area exposed the highest number of at-risk people to year-round particle pollution. Dukes, Plymouth, Suffolk, and Worcester counties all received C's and D's, lower grades than past year.
As temperatures rise, ozone is more likely to form and becomes harder to clean up, the report stated.
"People don't understand how unsafe ozone really is", said Ellen Penrod, executive director of the American Lung Association in Colorado.
The report states that California has seven of the ten most ozone polluted cities in the United States, with Los Angeles being the top (LA had almost 120 days in which ozone was above the healthy limit).
"Denver residents should be aware that we're breathing unhealthy air, placing our health and lives at risk", JoAnna Strother, regional director of public policy for the Lung Association, said in a statement.
The country as a whole recorded more days with hazardous air quality than ever from 2015 to 2017, the researchers said, defined as air that reaches "emergency conditions" on the government's air quality index.
Bangor, Maine, tops the report's list of cleanest cities, followed by Burlington, Vermont, and Honolulu.