The American Lung Association’s 2016 “State of the Air” report found Phoenix fifth-most polluted city in the nation for ozone. Compared to the 2015 report, Phoenix has cut ozone slightly. This is in keeping with a trend seen across the nation of lower ozone pollution levels.

“The 2016 ‘State of the Air’ report finds unhealthful levels of ozone in Phoenix, putting our local citizens at risk for premature death and other serious health effects such as asthma attacks and cardiovascular harm. And, since we have such high levels of year-round particle pollution, our citizens face increased risk for lung cancer,” said Julie Reid, Executive Director of the American Lung Association in Arizona. “Across the nation, the report found continued improvement in air quality, but more than half of the people in the United States live in counties that have unhealthful levels of either ozone or particle pollution.”

Each year the “State of the Air” reports on the two most widespread outdoor air pollutants, ozone pollution and particle pollution. 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 be lethal. But the trends reported in this year’s report, which covers data collected in 2012-2014, are strikingly different for these pollutants nationwide, and also in Phoenix.

Ozone Pollution in Phoenix

Compared to the 2015 report (2011-2013), Phoenix experienced fewer unhealthy days of high ozone in this year’s report.

“Ozone is harmful to public health and especially children, older adults and those with asthma and other lung diseases,” said Reid. “When older adults or children with asthma breathe ozone-polluted air, too often they end up in the doctor’s office, the hospital or the emergency room.”

Nationwide, ozone pollution has decreased because the nation has cleaned up major sources of the emissions that create ozone, especially coal-fired power plants and vehicles. However, according to research, climate change causes warmer temperatures, which makes ozone harder to clean up.

Particle Pollution in Phoenix

The 2016 report also found year-round particle pollution (soot) levels in 2012-2014 slightly lower than the 2015 report. Nationwide, the best progress in this year’s report came in reducing year-round levels of particle pollution.

“Particle pollution is made of soot or tiny particles that come from coal-fired power plants, diesel emissions, wildfires and wood-burning devices. These particles are so small that they can lodge deep in the lungs and trigger asthma attacks, heart attacks and strokes, and can even be lethal,” said Reid. “Year-round particle pollution levels have dropped thanks to the cleanup of coal-fired power plants and the retirement of old, dirty diesel engines.”

The 2016 report also tracked short-term spikes in particle pollution, as these can be extremely dangerous and even lethal. According to the 2016 report, Phoenix has fewer days when short-term particle pollution has reached unhealthy levels in 2012-2014. This is in spite of a trend seen across the nation of short-term spikes in particle pollution.

Increased heat, changes in weather patterns, drought and wildfires are all related to climate change, which has contributed to the extraordinarily high numbers of days with unhealthy particle pollution in some cities, including Phoenix.