Colorado Cities Rank Among Worst in Nation for Ozone Pollution; Report Reveals Nationwide Disparities for People of Color

Denver, Fort Collins, Colorado Springs each listed among 25 worst cities for ozone pollution in American Lung Association’s 2023 “State of the Air” report
Denver (6th), Fort Collins (15th), and Colorado Springs (20th) each ranked among the 25 worst cities in the nation for ozone pollution, according to the American Lung Association’s 2023 “State of the Air” report, which was released today.While ozone pollution in all three cities got worse compared with last year’s report, Colorado Springs experienced a significant increase in the number of unhealthy ozone days, making it a new addition to the list this year. Denver also recorded its worst-ever levels for short-term particle pollution. Nationally, the report found that nearly 120 million people, or more than one in three, in the U.S. live in counties that had unhealthy levels of ozone or particle pollution.

The Lung Association’s 24th annual “State of the Air” report grades Americans’ exposure to unhealthy levels of ground-level ozone air pollution, annual particle pollution and short-term spikes in particle pollution over a three-year period. This year’s report covers 2019-2021.

“The data in this year’s report illustrate the urgency to improve air quality in Colorado,” said Nick Torres, advocacy director for the Lung Association. “We are calling on the Air Quality Control Commission to adopt new zero-emission truck standards, so that Colorado can address one of the leading contributors to our state’s ozone pollution problem.”

Nationally, the report found that ozone pollution has generally improved across the nation, thanks in large part to the success of the Clean Air Act. However, more work remains to fully clean up harmful pollution, and short-term particle pollution continues to get worse. In addition, some communities bear a greater burden of air pollution. Out of the nearly 120 million people who live in areas with unhealthy air quality, a disproportionate number – more than 64 million (54%) – are people of color. In fact, people of color were 64% more likely than white people to live in a county with a failing grade for at least one measure, and 3.7 times as likely to live in a county with a failing grade for all three measures.

Ground-level Ozone Pollution in Colorado
Compared to the 2022 report, Denver experienced more unhealthy days of high ozone in this year’s report. “State of the Air” ranked Denver as the 6th most polluted city for ozone pollution, one spot worse compared to the city’s 7th place ranking in last year’s report. For the second consecutive report, every county in the Denver region received a failing grade for ozone pollution.

Fort Collins experienced more unhealthy days of high ozone in this year’s report, again ranking the city among the nation’s most polluted for ozone pollution (15th) – three spots worse compared to the city’s 18th place ranking in 2022.

Colorado Springs was a new addition to the top 25 most polluted cities for ozone, ranking 20th in this year’s report.

Particle Pollution in Colorado
The report also tracked short-term spikes in particle pollution, which can be extremely dangerous and even deadly. Wildfires in 2020 and 2021 made a clear impact on air quality data in this year’s report. Denver’s recorded its worst-ever grades for short-term particle pollution in this year’s report. The Denver metro area is ranked 18th-worst nationally for short-term particle pollution. Boulder County, reported its most unhealthy days ever for short-term particle pollution, and the most in the Denver region.

Short-term particle pollution in Fort Collins also increased to its worst levels ever, with the average unhealthy days increasing from 4.8 days in last year’s report to 5.5 days in this year’s report.

Weld County also experienced more unhealthy particle pollution days (5.7) compared with last year’s report (4.7), earning an F in this category for the second consecutive year.

The 2023 “State of the Air” found that year-round particle pollution levels in Colorado were slightly worse overall than in last year’s report, but all counties earned passing grades. Two Colorado cities ranked among the cleanest cities nationally in this category, Colorado Springs (9th) and Grand Junction (12th).

The American Lung Association is calling on President Biden to urgently move forward on several measures to clean up air pollution nationwide, including new pollution limits on ozone and particle pollution and new measures to clean up power plants and vehicles. See the full report results and sign the petition at

Media Resources
For more information, contact:

James A. Martinez
(312) 445-2501
[email protected]

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