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Press Release
Air Quality

PHOENIX (April 19, 2023) — The American Lung Association’s 2023 State of the Air (SOTA) report released today shows Arizona had fewer unhealthy days for ozone and particle pollution statewide for the period 2019 – 2021 as compared with last year’s report. The Lung Association developed its annual SOTA report rankings using air quality data for the two most widespread pollutants in the United States — ozone and fine particulate matter. These pollutants pose a public health concern when they reach unhealthy levels.

“As a southwestern desert state with the sunniest cities in the country and increasing wildfires in the western U.S, Arizona, like our neighboring states, shares real air quality challenges when it comes to ozone and particle pollution,” said Daniel Czecholinski, ADEQ Air Quality Division Director. “While we’ve achieved significant improvements in overall air quality over the last 30 years from a 70 percent reduction in emissions — even as Arizona’s population has grown and our economy thrived — more wildfires in the western U.S. create and transport more ozone and particle pollution into the state, which affects our air quality.”

Taking small actions through voluntary programs can add up to cleaner air for Arizona | What you can do to improve air quality >

“Both ozone and particle pollution can cause premature death and other serious health effects such as asthma attacks, cardiovascular damage, and developmental and reproductive harm,” said JoAnna Strother, Senior Director of Advocacy for the American Lung Association in Arizona. “Particle pollution can also cause lung cancer. To ensure a healthy future for Arizonans and visitors to our great state, we must continue our work together to improve air quality.”

American Lung Association State of the Air 2023 Report | View >

Ozone Levels

Unchanged from last year, the SOTA 2023 report ranks the Phoenix metropolitan area at 5th in the nation for unhealthy ozone days. Also unchanged from last year’s report for the number of high ozone days is the grade of “F” for Gila, Maricopa, Pima and Pinal Counties and the grade of “C” for Yuma County. The report also shows improved ozone grades for Coconino and La Paz counties, and that Flagstaff, Arizona, is one of the country’s cleanest cities for ozone pollution. Ground-level ozone pollution is created when nitrogen oxides (NOx) and volatile organic compounds (VOCs) chemically react in sunlight. On average, Arizona has more sunlight and less cloud cover than any other state in the nation. Yuma and Phoenix rank number one and two, respectively, as the sunniest cities in the U.S. and this means more sunlight reaches the ground giving ultraviolet radiation a greater chance to react and form more ozone. Compounds that form ozone also come from biomass (shrubs and trees), industry, wildfires, gas-powered garden equipment and more.

Other contributors to ozone pollution in Arizona include emissions from international sources, such as Mexico and China, and other states, such as California and ADEQ is working with our neighbors to better understand ozone transport in an effort to improve air quality for everyone.

In the Phoenix area, vehicles driving on the roads produce the majority of NOx and are the biggest contributor to man-made ozone. A major source of VOCs is plants (vegetation). If there are enough VOCs present, it takes very little NOx to increase ozone levels. And, because of the complexity of ozone formation, less NOx does not necessarily equal less ozone right away.

Ozone Fact Sheet | View >
EPA AQI Guide | View >

To help address the complex ozone problem, ADEQ is partnering with researchers at Arizona State University and the University of Arizona to conduct field studies to verify emissions, model and predict ozone concentrations and identify opportunities to mitigate high ozone levels, including development of potential incentives addressing ozone reduction strategies | View the ADEQ press release about new Arizona Board of Regents’ Grants >

Arizona motorists can improve air quality not only by driving or idling less, but by also keeping vehicles tuned and operating within federal emissions limits. In addition, all Arizonans can help improve air quality by selecting plants for our yards and businesses that produce lower VOCs.

ADEQ Voluntary Vehicle Repair Program | View >
Clean Air Make More Trees & Air Quality in Maricopa County | View >

Particle Levels: PM2.5

The SOTA 2023 report changed the national ranking for year-round particle pollution, measured in small particulate matter or PM-2.5, for the Phoenix metropolitan area from 8th to 7th place, which is shared with two other metro areas in California and Oregon. For the number of high particle pollution days, grades for Maricopa, Pinal and Santa Cruz counties remained unchanged from last year’s report, with each receiving an “F”. Two Arizona counties – Apache and Pima – made the list of cleanest counties in the country for daily particle pollution.

During Arizona’s winter holiday season, the combination of smoke from burning wood in fire pits, fireplaces and fireworks and calm, cool weather can cause high levels of particulate matter pollution.

ADEQ Air Quality Data | View >
Particulate Matter Fact Sheet | View >

By switching to propane instead of wood and reducing the use of fireworks, especially during periods of calm winter weather, we can reduce the air pollution that settles over valleys across Arizona during the winter holiday season.

ADEQ encourages Arizonans to stay informed about air quality conditions to protect their health and to learn more about how our individual actions can improve air quality every day, and especially at times when ADEQ air quality meteorologists provide early information about the potential for high pollution days. ADEQ is committed to making information about air quality and health clear and accessible to everyone:

ADEQ Air Arizona Mobile App | View >
ADEQ Air Quality Forecasts | View >
Voluntary Programs to Improve Air Quality | View >


ADEQ Public Information Officer
602-540-8072 | Email >