Apr 20, 2023 - News

Valley has some of nation's worst air pollution, but it's not all bad

Illustration of a test featuring a pair of lungs with an F on it

Illustration: Sarah Grillo/Axios

The American Lung Association (ALA) released its annual State of the Air report Wednesday, showing the Valley to have some of the worst ozone and particulate pollution in the U.S.

  • Each report covers a three-year period, and the latest analyzed 2019-2021.
  • Maricopa County saw mixed results, with some metrics improving and others worsening, while the state as a whole saw a decrease in high-pollution days during that period.

The big picture: Nearly 64 million Americans live in areas with "failing grades for daily spikes in deadly particle pollution," the ALA reported.

Why it matters: Ozone and particle pollution cause respiratory problems and other health-related issues.

Zoom in: The ALA ranked the Phoenix-Mesa area as having the fifth worst ozone pollution of any metro in the U.S., seventh worst year-round particle pollution and 13th worst short-term particle pollution.

  • The Valley's ranking for ozone pollution didn't change, while it dropped one spot for annual particle pollution and improved by two spots on daily particulate pollution from the ALA's 2022 report.

Details: The numbers are worse for the Phoenix-Mesa area than Maricopa County as a whole, with annual particulate pollution exceeding the National Ambient Air Quality Standards since the 2016-2018 period and increasing slightly since the last report.

  • The Valley also had a weighted average of 41.2 high-ozone days per year in 2019-2021, an increase from the 39.3 in 2018-2020.
  • There was a drop in the weighted average number of high-particle days, but not enough to get us out of failing territory.

Zoom out: Maricopa County received F grades for ozone and short-term particle pollution, while getting a passing grade for annual particle pollution.

  • On yearly concentration of fine particulate matter, Maricopa County earned a passing grade and has been below the national standard since the 2007-2009 report.

Yes, but: Statewide, there were fewer high-ozone days and high-particulate days in 2019-2021 than in 2018-2020, according to the ALA report.

The bottom line: Matthew Fraser, a professor at ASU's School of Sustainable Engineering and the Built Environment, said the report showed mixed results for the Valley.

  • "I don't think anybody would say that we have been as successful as people would hope to be in mitigating and controlling ozone pollution and particulate matter pollution," he told Axios Phoenix.

The other side: While the numbers for the Phoenix area weren't great and grades were mixed in other counties, the Arizona Department of Environmental Quality (ADEQ) said the state has moved in the right direction when it comes to air pollution.

  • ADEQ noted in a press statement that Arizona had fewer unhealthy days in last year's report than this year's.
  • The agency's statistics show Phoenix with more high-ozone days from 2018-2020 than 2019-2021.
  • Matt Pace, an ADEQ air quality meteorologist, says the agency uses federal standards that differ from ALA's.

What they're saying: "Things are getting better. There is obviously just more work to do," Pace says.

Of note: Pinal County was one of 11 nationwide with failing grades in all three categories.

  • The rest were in California, which experienced a spate of wildfires during that period.

What we're watching: The EPA downgraded the Phoenix area's ozone pollution rating from "marginal" to "moderate" last year, and if it doesn't meet federal standards by next summer, a likely scenario, there'll be serious consequences.

  • Companies that open or expand operations here will have to invest in expensive environmental offsets.

Get more local stories in your inbox with Axios Phoenix.


Support local journalism by becoming a member.

Learn more

More Phoenix stories

No stories could be found


Get a free daily digest of the most important news in your backyard with Axios Phoenix.


Support local journalism by becoming a member.

Learn more