Minnesota’s most polluted counties detailed in State of Air report

MINNEAPOLIS (FOX 9) - An annual report that measures the level of dangerous pollutants in the air has released its 2025 findings that detail which areas are more worrisome than others.

State of the Air report

What we know:

The Clean Air Act requires the U.S. Environmental Protection Agency (EPA) to set health-based standards for six outdoor air pollutants considered dangerous: particulate matter, ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide and lead.

In 2000, the American Lung Association launched its annual "State of the Air" report examining the most widespread and dangerous pollutants – fine particulate matter and ozone – providing the public with information about the quality of air in their communities.

The Lung Association calculates various air pollutants and assigns grades for daily and long-term measures of particle pollution and daily ozone, then uses the measurements to rank cities and counties.

This year’s report represents data gathered from 2021, 2022 and 2023 – the most recent three years of quality data publicly available.

Minnesota’s most and least polluted

Dig deeper:

According to the most recent report, Anoka (ozone) and Dakota (particle) counties had the worst grades in Minnesota.

On the flip side, Carlton County is ranked the fifth-cleanest in the U.S. for year-round particle pollution.

Carlton and Lake counties also led the statewide rankings for best ozone conditions.

Minnesota counties pollution chart in the 2025 State of the Air report.

Big picture view:

According to the data, 37% of the U.S. population, roughly 125.2 million people, were exposed to levels of ozone that put their health at risk – an increase of 24.6 million people more than the last report.

Health officials believe ozone gas can be a powerful lung irritant that reacts with the lining of the small airways, causing inflammation and other damage that can impact multiple body systems, the report says.

The 2025 State of the Air report also found that 46% of Americans — roughly 156.1 million people — are currently living in places that get failing grades for unhealthy levels of ozone or particle pollution.

By the numbers:

According to the report, the Los Angeles-Long Beach area of California is the most ozone-polluted city in the U.S., while the Bakersfield-Delano area of the state deals with the most particle pollution.

Casper, Wyoming, was ranked as the cleanest area for year-round particle pollution, while Augusta-Richmond County in Georgia-South Carolina has the cleanest ozone.

A copy of the full 155-page report can be found below: