Idaho Counties and Cities Rank as Some of the Most Polluted in the U.S.

Despite continued improvement in air quality in the U.S., residents health remains at risk from unhealthy air, according to American Lung Associations 19th annual air quality report.

The American Lung Association’s State of the Air 2018 report shows Idaho has mixed grades when it comes to air quality as measured by short and long-term particle pollution and ozone pollution.  The trends reported in this year’s report, which covers data collected by states, cities, counties, tribes and federal agencies in 2014-2016, reflect the ongoing challenges to reduce air pollution.

Franklin County in Southeast Idaho, part of the reporting areas for Logan, UT, ranks as the eleventh most polluted area in the nation for short-term particle pollution. This ranking is an improvement over last year’s report, when it was the eight most-polluted area in the nation.

Similarly, Lemhi County and Shoshone County rank as the 14th and 17th most-polluted counties respectively for year-round particle pollution, and both counties fail to meet the national air quality standards. Lemhi County and Shoshone County also rank as the 13th and 12th most-polluted counties respectively for short-term particle pollution levels.

“Across the nation, the report found continued improvement in air quality, but  more than 40 percent of Americans – 133.9 million – still live in counties that have unhealthy levels of ozone or particle pollution,” said Heather Kimmel, Executive Director of the American Lung Association in Idaho. “The 2018 ‘State of the Air’ report finds that unhealthy levels of pollution across the nation, and in Idaho, puts residents at risk for premature death and other serious health effects such as asthma attacks and greater difficulty breathing for those with lung diseases like COPD.”

Reports on the levels of ozone pollution in parts of Idaho were more positive:  Butte County received an A for its low level of ozone pollution, and the Idaho Falls-Rexburg-Blackfoot area ranks as one of the cleanest areas for ozone pollution with zero unhealthy air days.

Ozone levels in Ada County, however, were less positive.  “With record-setting heat in 2016 and 2017, high ozone days increased dramatically which puts people at risk, including those in Ada County which received a D for its high level of ozone in this year’s report,” Kimmel continued.

Each year the “State of the Air” provides a report card on the two most widespread outdoor air pollutants, ozone pollution, also known as smog, and particle pollution, also called soot. The report analyzes particle pollution in two ways: through average annual particle pollution levels and short-term spikes in particle pollution. Both ozone and particle pollution are dangerous to public health and can increase the risk of premature death and other serious health effects such as lung cancer, asthma attacks, cardiovascular damage, and developmental and reproductive harm.

“We can and should do more to protect our public health from bad air,” Kimmel said. “Good progress has been made through legislation like the federal Clean Air Act. The American Lung Association works to defend and strengthen this law.”

Climate change is increasing our air pollution problems. Warmer temperatures linked to climate change increase the frequency and severity of weather patterns, drought, and wildfire.  Wildfire in particular contributed to the high number of days with unhealthy particle pollution in some areas, including those in Idaho. 

For more information about Idaho’s air quality data and grades for each county and reporting area, visit For media interested in speaking with an expert, please contact Holly Harvey at the American Lung Association at (206) 512-3292 or [email protected].


For more information, contact:

Holly Harvey
(206) 512-3292
[email protected]

Asthma Basics Workshop - National
, | Apr 17, 2024
Asthma Basics Workshop - National
, | May 07, 2024