Salt Lake City air quality has slightly improved — and one Utah city ranks among the best in U.S.

The findings were released Thursday in the American Lung Association’s 2022 report.

A new report by the American Lung Association found that while pollution in Salt Lake City and Logan has slightly improved, St. George ranks among the nation’s cleanest cities.

The Salt Lake City metropolitan area this year reached its “lowest ever” measurement for short-term particle pollution, the report states. But it still ranks within the top 25 worst cities for such pollution nationally, claiming the 20th-worst rank, better than the 17th-worst rank it held in last year’s report.

Two years ago, the metropolitan area ranked seventh. In the report released this week, the short-term particle pollution category was calculated using 24-hour average pollution concentration rates from 2018-2020.

Short-term particle pollution is caused by a buildup of fine particulate matter, or PM2.5, which worsens the hazy skies over the Salt Lake Valley during inversion events. It usually comes from transportation emissions or stationary sources, like woodburning and home heating, according to the Department of Environmental Quality.

Salt Lake City also ranked two spots better this year for ozone pollution, moving from the eighth-worst city in the U.S. to the 10th. Ozone pollution occurs when a combination of other pollutants — typically produced when fossil fuels like gasoline, diesel, or coal are burned — “cook” together in sunlight.

Those pollutants are usually emitted from power plants, motor vehicles and other sources of high-heat combustion, according to the report.

Statewide pollution levels

The Logan area experienced a more significant improvement in short-term particle pollution, moving from 7th-worst to 18th-worst in terms of the nation’s most polluted cities. Logan also saw fewer unhealthy days, where levels of particle pollution spiked.

Overall, the state’s year-round particle pollution levels — calculated using annual concentration rates by county — were slightly worse overall than in last year’s report, but all counties earned passing grades.

Of the 14 Utah counties included in the report, Davis, Duchesne, Salt Lake, Uintah, Utah and Weber counties all received an “F” grade for high ozone days.

Iron County was the only county in Utah (of the 14 included) with an “A” grade at zero high ozone days. It was followed by Garfield with a “B” grade; Cache, Washington and Carbon with “C” grades; and Box Elder, San Juan and Tooele with “D” grades.

St. George ranked well for air quality

Although Washington County had a “C” grade for high ozone days, the city of St. George ranked among the country’s cleanest cities for short-term and year-round particle pollution. The area reported zero days in which short-term particle pollution levels reached the unhealthy air quality range.

Nationwide, more “very unhealthy” and “hazardous” air quality was reported than ever before in the report’s 20-year history, and the association called on the Biden administration to strengthen standards on particulate matter air pollution.

“Despite some recent improvements, the levels of ozone and particle pollution seen in several areas of Utah can still harm the health of all of our residents,” said Nick Torres, advocacy director for the American Lung Association, in a news release.

“But particularly at risk are children, older adults, pregnant people, and those living with chronic disease,” Torres’ statement continued. “Both ozone and particle pollution can cause premature death and other serious health effects such as asthma attacks, cardiovascular damage, and developmental and reproductive harm.”