PHOENIX — The American Lung Association’s 2020 “State of the Air” report found Phoenix ranked among the nation’s worst cities for widespread air pollutants — ozone and particulates — both of which can be deadly.

Both Phoenix and Tucson are heavily impacted by unhealthy ozone and particle pollution and, in fact, the Phoenix metro area ranks in the top 10 in those categories, with the Tucson metro area also worsening in all categories.

The Lung Association’s annual air quality “report card” tracks Americans’ exposure to unhealthful levels of particle pollution and ozone during a three-year period. Once again, the report found that nearly half of all Americans were exposed to unhealthy air in 2016-2018. Pollution places the health of residents at risk, including those who are more vulnerable to the effects of air pollution such as older adults, children and those with a lung disease.

“This year marks the 50th anniversary of the Clean Air Act, which has been responsible for dramatic improvements in air quality,” said American Lung Association Senior Advocacy Director JoAnna Strother. "Overall, people in Arizona face significant air quality challenges. Transportation, wood stoves, coupled with extreme heat and droughts come more frequently as our climate changes, our air pollution burdens are placing our health and lives at risk.

"With nearly half of Americans — and almost all Arizonans — breathing unhealthy air, our ‘State of the Air’ report shows that because of climate change, the nation is heading in the wrong direction when it comes to protecting public health — especially in the western United States.”

Each year the “State of the Air” is a report card on the two most widespread outdoor air pollutants, ozone pollution, also known as smog, and particle pollution, also called soot. The report analyzes particle pollution in two ways: through average annual particle pollution levels and short-term spikes in particle pollution. Both ozone and particle pollution are dangerous to public health and can increase the risk of premature death and other serious health effects such as asthma attacks, cardiovascular damage, and developmental and reproductive harm. Particle pollution can also cause lung cancer, and new research links air pollution to the development of serious diseases, such as asthma and dementia.

This year’s report covers 2016, 2017 and 2018, the years with the most recent quality-assured data available collected by states, cities, counties, tribes and federal agencies. Notably, those three years were among the five hottest recorded in global history. Rising temperatures lead to increased levels of ozone pollution. Changing climate patterns also fuel wildfires and their dangerous smoke, which increase particle pollution. Ozone and particle pollution threaten everyone, especially children, older adults and people living with a lung disease. Although this report does not cover data from 2020, amid the COVID-19 pandemic, the impact of air pollution on lung health is of heightened concern. Learn more about that at

Compared to the 2019 report, the Phoenix metro area, including Maricopa, Pinal and Gila counties, saw worse unhealthy days of ozone levels and all earned F grades. Only Flagstaff and Yuma metro areas saw slight improvements for ozone.

“Ozone pollution can harm even healthy people but is particularly dangerous for children, older adults and people with lung diseases like COPD or asthma,” said Strother. “Breathing ozone-polluted air can trigger asthma attacks in both adults and children with the disease, which can land them in the doctor’s office or the emergency room. Ozone can even shorten people’s lives.”

This report documents that warmer temperatures brought by climate change are making ozone more likely to form and harder to clean up. Significantly more people suffered unhealthy ozone pollution in the 2020 report than in the last three “State of the Air” reports.

“State of the Air” 2020 found that year-round particle pollution levels in the Phoenix metro area significantly worsened, while Tucson metro and Yuma slightly increased. There is no particle pollution data available for Flagstaff.

“Particle pollution can lodge deep in the lungs and can even enter the bloodstream. It can trigger asthma attacks, heart attacks and strokes and cause lung cancer,” said Strother. Particle pollution comes from coal-fired power plants, diesel emissions, wildfires and wood-burning devices.

“Year-round particle pollution levels had dropped in recent years thanks to the cleanup of coal-fired power plants and the retirement of old, dirty diesel engines. However, the increase we’ve seen nationally in particle pollution in this year’s report is a troubling reminder that we must increase our efforts to reduce this dangerous pollution,” Strother said.

While the report examined data from 2016-2018, this 21st annual report also provides air pollution trends back to the first report. Learn more about Arizona’s rankings, as well as air quality across the nation, in the 2020 “State of the Air” report at