These Arizona counties have the worst air pollution

Anyone living in Phoenix doesn’t need to do much more than peer outside their air-conditioned boxes we call homes to know that pollution levels are bad.

Thanks to a report released this week by the American Lung Association, we can say exactly how bad.

Phoenix was ranked the fourth-worst metro area in the United States for high ozone days and 20th-worst for year-round particle pollution.

Ozone reaches particularly high levels when it’s hot and sunny, making Phoenicians prime candidates for suffering from the harmful effects caused by breathing it. It can cause a number of symptoms, including coughing, sore or scratchy throat, inflammation of the airways and aggravation of asthma and other lung diseases.

Year-round particle pollution, also known as PM2.5, indicates how much dirt, dust, smoke and other pollutants are in the air. In addition to some of the effects of ozone, particle pollution can harm lung development in children.

But Phoenix isn’t alone in Arizona when it comes to atrocious air. According to the ALA, two of Arizona’s counties earned “F” ratings for air pollution. In addition, four counties earned the same abysmal rating for high ozone days. Maricopa and Pinal counties earned the dubious distinction in both categories, while Gila and Pima both snagged “F” grades for high ozone days.
Maricopa’s annual count of high ozone days was far worse than any of the other three counties. From 2021 to 2023, there were a total of 149 “orange” days — when ozone is unhealthy for sensitive groups. During that same period, there were nine “red” days and one “purple” day, which are code for unhealthy and very unhealthy, respectively. In total, it’s an average of more than 50 days a year that ozone is unhealthy in the Valley. The next closest county, Pinal, averaged about 20 a year.

Both the Environmental Protection Agency and the Maricopa Association of Governments find that air quality in Phoenix is seriously unhealthy. The EPA has changed its label for pollution levels in the Valley to “serious,” which could bring more restrictions on emissions and affect growth in the county.

Arizona lawmakers have asked the EPA under the Trump administration to intervene. Democratic Sen. Mark Kelly asked EPA Administrator Lee Zeldin to change federal ozone guidance to make it easier for Maricopa County to show that much of the Valley’s air pollution comes from outside Arizona, while far-right GOP Rep. Andy Biggs asked Zeldin to just change Maricopa County’s ozone rating.

It’s been estimated that as much as 80% of Arizona smog drifts in from Mexico and California, which has prompted Arizona Republicans to ask Attorney General Kris Mayes to sue other states and counties. Lawmakers have claimed that the current EPA guidance would only hurt Arizona’s economy and wouldn’t improve air quality.

The EPA announced earlier this month that it would make the changes Kelly asked for.

“This decision is one more step forward to help improve our state’s air quality and keep growing the economy," Kelly said in a statement at the time.