As summer approaches and the weather heats up, levels of ozone pollution increase and are frequently prompting air quality advisories from the Arizona Department of Environmental Quality.

Ozone frequently moves from the Valley to outlying areas such as Fountain Hills, where levels can be among the highest.

The American Lung Association’s State of the Air 2019 report shows that ozone levels improved in some Arizona counties. However, pollutants that contribute to ozone continue to impact a third of Arizona counties, including those with large metropolitan areas, which received grades of “D” or “F.” Grades in the report are determined according to the levels of ozone and particulate matter (PM-2.5) in the air during 2015 - 2017.

Ozone Pollution

Portions of four counties in Arizona — Gila, Maricopa, Pinal and Yuma — earned an “F” for having too many individual days when ozone reached unhealthy levels in the Air Quality Index (AQI), more than the last report. Monitors in Maricopa, Pinal and Gila Counties are part of the Phoenix metropolitan area, which is ranked as the seventh most ozone-polluted city in the nation.

“Just like any grades we want an A+, especially when it comes to air quality and public health. Here at ADEQ, we hit the books, studied hard and found vehicle emissions are the biggest contributor to ozone pollution in Phoenix and Tucson,” said Timothy Franquist, ADEQ Air Quality Director. “It’s now time for each of us to look at what we can do to improve air quality. Simply driving less, carpooling or vanpooling, taking the bus, bicycling to work or telecommuting can eliminate thousands of tons of pollution each year.”

Additionally, emissions from international sources, such as Mexico and China, and other states, such as California, contribute to ozone pollution in Arizona. Compounds that form ozone also come from biomass (shrubs and trees), industry, wildfires, gas powered garden equipment and more.

“Ozone pollution and particle pollution are two of the most widespread and dangerous air pollutants. Breathing these pollutants can cause asthma attacks, respiratory and cardiovascular harm, and even early death. Breathing particle pollution can also cause lung cancer,” said JoAnna Strother, Director of Advocacy for the American Lung Association in Arizona. “With 6 million people in Arizona we can all do our part by committing to driving less or using other forms of transportation. Together we can make a difference in our air quality.”

Be Air Aware

As Arizona heads into summer, longer days raise the potential for higher ozone levels. Sunshine converts pollutants, such as nitrous oxides and volatile organic compounds (VOCs) found in vehicle emissions, into ozone.

The State of the Air 2019 report also found all counties in Arizona earned a passing grade for year-round particle levels known as PM-2.5, which is particulate matter found in smoke or very fine dust. However, both Maricopa County and Pinal County earned an “F” for having too many individual days when particle pollution spiked to unhealthy levels.

During holiday periods when fireworks are legal or when cooler weather prompts lighting wood burning fireplace and fire pits, smoke levels are often elevated in Maricopa County.