New ‘State of the Air’ Report Finds Boise Metro Area Continues to Struggle with Ozone and Particle Pollution

Today, the American Lung Association released the 2025 “State of the Air” report, which reveals that Boise metro area was named 36th most polluted in the nation for particle pollution. Nationally, the report found that 156 million people (46%) are living in areas that had unhealthy levels of air pollution.

The Lung Association’s 26th annual “State of the Air” report grades exposure to unhealthy levels of ground-level ozone air pollution (also known as smog), and year-round and short-term spikes in particle pollution (also known as soot) over a three-year period. The report looks at the latest quality-assured air quality data from 2021-2023.

“The air pollutants covered in this report are widespread and can impact anyone’s health. Both ozone and particle pollution can cause premature death and other serious health effects such as asthma attacks, heart attacks and strokes, preterm births and impaired cognitive functioning later in life. Particle pollution can also cause lung cancer,” said Heather Kimmel, Division Director of Health Promotions for the American Lung Association. “Unfortunately, too many people in Boise metro area are living with unhealthy levels of ozone and particle pollution. This air pollution is causing kids to have asthma attacks, making people who work outdoors sick and unable to work, and leading to low birth weight in babies. We urge Idaho policymakers to take action to improve our air quality, we are calling on everyone to support the incredibly important work of the U.S. Environmental Protection Agency (EPA).”

Ground-level Ozone Pollution in the Boise City-Mountain Home-Ontario, ID-OR metro area:

The “State of the Air” report looked at levels of ozone “smog,” the air pollutant affecting the largest number of people in the United States. The Boise City-Mountain Home-Ontario, ID-OR metro area ranked 46th worst in the nation for ozone pollution. The ranking was based on the area’s worst county’s average number of unhealthy days—5.7 days per year, an F grade, in Ada County, Idaho. This was better than the area's ranking in last year's report of 36th worst, with 5.3 days per year, an F grade. 

Particle Pollution in the Boise City-Mountain Home-Ontario, ID-OR metro area:

The report also tracked short-term spikes in particle pollution, which can be extremely dangerous and even deadly. The Boise City-Mountain Home-Ontario, ID-OR metro area ranked 36th worst in the nation for short-term particle pollution. The ranking was based on the area’s worst county’s average number of unhealthy days—4.8 days per year, an F grade, in Canyon County, Idaho. This was better than the area's ranking in last year's report of 17th worst, with 10.7 days per year, an F grade. 

For the year-round average level of particle pollution, the area’s worst county, Canyon County, Idaho, received a passing grade for pollution levels below the federal standard. The Boise City-Mountain Home-Ontario, ID-OR metro area ranked 77th worst in the nation. This was worse than the area's ranking in last year's report of 111th worst in the nation.

The “State of the Air” report found that 156 million people in the U.S. (46%) live in an area that received a failing grade for at least one measure of air pollution and 42.5 million people live in areas with failing grades for all three measures. The report also found that a person of color in the U.S. is more than twice as likely as a white individual to live in a community with a failing grade on all three pollution measures. Notably, Hispanic individuals are nearly three times as likely as white individuals to live in a community with three failing grades.

In this year’s “State of the Air” report, the Lung Association is calling on everyone to support the U.S. Environmental Protection Agency. EPA is essential to protecting people’s health from ozone and particle pollution. Without EPA staff and programs, families won’t know what’s in the air they are breathing, and efforts to clean up air pollution will be undone. Join the American Lung Association in advocating to protect EPA’s expert staff and lifesaving programs. See the full report results and take action at Lung.org/sota.