Arizona’s Air Quality Released for Particle Pollution & Ozone

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News Release Arizona's air quality report

American Lung Association State of the Air Report 2021 for 2017-2019 Ranks Arizona’s Air Quality Improved for Particle Pollution and
Worse for Ozone Pollution

PHOENIX (April 21, 2021) – The American Lung Association State of the Air 2021 report released today. It shows an improved national air quality ranking for Arizona for particle pollution and a worse ranking for ozone pollution for the period 2017-2019. The Lung Association developed its annual State of the Air Report rankings using pre-pandemic 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, Arizona, like our neighboring states, shares real air quality challenges when it comes to particle and ozone pollution,” said Daniel Czecholinski, ADEQ Air Quality Division Director. “The weather and climate Arizonans and visitors appreciate but don’t control play a significant role in unhealthy air quality days and underscore the importance of knowing what affects quality and what actions we can take together to protect our health and improve air quality for each other. Factors affecting Arizona’s air quality have shifted significantly since the federal Clean Air Act Amendments in 1990.

Overall, our air quality is much improved. This is thanks to a 68 percent reduction in emissions — even as Arizona’s population has grown and our economy thrived. Subsequently, we can continue to improve the quality of the air we breathe by working together as a community. Home to around 7 million people, small, individual actions we can take can add up to big air quality improvements we all want to protect our health.”

Taking small actions through voluntary programs can add up to cleaner air for Arizona.

What you can do to improve air quality >

“As the science linking ozone and particle pollution to negative health impacts continues to grow, it remains essential that we continue every effort to maintain and improve air quality across the state to protect everyone living and visiting Arizona today and in the future,” said JoAnna Strother, Senior Director of Advocacy for the American Lung Association in Arizona.

American Lung Association State of the Air 2021 Report | View >

Ozone Levels

The report ranks the Phoenix metropolitan area at 5th in the nation for unhealthy ozone days. Gila, Maricopa, Pima, Pinal and Yuma Counties each received an “F” for the number of high ozone days. 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. 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. 

In the Phoenix area, vehicles driving on the roads produce the majority of NOx. They 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 >

Additionally, emissions from international sources, such as Mexico and China, and other states, such as California, contribute to ozone pollution in Arizona. ADEQ is working with our neighbors to better understand ozone transport in addition to sharing data and learnings to improve air quality for everyone. 

Transboundary transport of ozone pollution to a US border region:

A case study of Yuma (Environmental Pollution Volume 273, 15 March 2021, 116421) | View >

To develop a clearer, more comprehensive understanding of ozone formation in Phoenix, ADEQ is partnering with Arizona State University – W. P. Carey School of Business on a unique project called the Phoenix Ozone Variable Importance Analysis (VIA). The VIA project is using a novel, non-regulatory modeling approach to gain a new and deeper understanding of ozone formation not found in conventional models with the longer-term goal of building better programs, expanding our toolkit for ozone forecasting and public outreach and developing recommendations for reducing ozone levels.

Phoenix Ozone VIA | View >

We can improve the air not only by driving or idling less, but by also keeping our vehicles tuned and operating within federal emissions limits. In addition, we 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: PM-2.5

The State of the Air 2021 report ranks the Phoenix metropolitan area 8th in the nation for year-round particle pollution. These are measured in small particulate matter or PM-2.5, and a slight improvement from last year’s 7th place ranking. Maricopa and Pinal Counties each received an “F” for the number of days with high particle pollution. Phoenix had fewer unhealthy particle pollution days as compared to the previous report. The city is no longer ranked among the top 10 cities. 

More active weather patterns during the 2019 winter holiday season resulted in lower particle pollution levels in Maricopa County, with the only PM 2.5 level higher than the federal standard occurring on New Year’s Eve. These weather conditions helped improve the prior report’s ranking, which reflected some of the worst winter holiday particulate matter pollution recorded in Maricopa County due to a combination of smoke from burning wood in fire pits, fireplaces and fireworks and calm, cool weather with little wind and no rain. 

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. Arizona Department of Environmental Quality is committed to making information about air quality and health clear as well as accessible to everyone:

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


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