With summer ozone season about to start, here’s what you need to know

FOR IMMEDIATE RELEASE:  Thursday, May 29, 2025

DENVER – While June 1 marks the unofficial start of summer in the minds of many Coloradans, it also marks the official start of the ozone season on the Front Range. 

At a news conference Thursday, CoPIRG Foundation unveiled new online maps of state air quality data so Coloradans can see at a glance where bad ozone pollution has occurred in recent years. Some of those locations include Chatfield State Park in Douglas County, the town of Evergreen, on South Table Mountain in Golden, the city of Manitou Springs and Boulder Reservoir. Monitors even recorded elevated ozone levels up in the mountains in Black Hawk and Rocky Mountain National Park.

“Ozone is a regional air pollutant, so some of the locations in our state with the worst ozone pollution may surprise you,” said CoPIRG Foundation Clean Air Advocate Kirsten Schatz. “Too many of the places with high levels of harmful ozone pollution – from Chatfield to Evergreen and Rocky Mountain National Park – are destinations where Colordans love to exercise and enjoy outdoor recreational activities. But given our poor air quality, on many summer days, spending time outdoors can do more harm to your health than good.”

Advocates recommend signing up for ozone alerts from the state and the Regional Air Quality Council and following tips for reducing the health risks on days when ozone is forecast to spike to unhealthy levels.

“Short-term ozone exposure is most dangerous for kids and adults with asthma, and for adults with COPD,” said Beth Gillespie, MD, a hospitalist physician at Denver Health and chair of Physicians for Social Responsibility Colorado. “As we continue to see higher heat extremes and ozone pollution, I’m concerned for the many patients I see with these conditions who struggle with their health, especially during the summer months.”

Ozone is a gas that helps reduce harmful UV radiation when it occurs high up in the atmosphere. However, ground-level ozone is associated with harmful health effects including asthma, lung damage and even cardiovascular disease.

In recent years, the Denver Metro/North Front Range region has suffered from some of the highest ozone pollution in the country. The region has failed to meet the national health-based air quality standards for ozone and in 2022, the EPA reclassified the region from “serious” to “severe” violation of the Clean Air Act.

“The American Lung Association’s 2025 “State of the Air” report found that Denver’s ozone pollution ranked 6th worst in the country – its 3rd year in a row at that spot,” said Justin Misuraca, state president of the Colorado Respiratory Care Society and American Lung Association – Colorado Leadership Board member. “Breathing ozone pollution hurts our health in many ways, and climate change is making it harder and harder to make the progress we need to ensure Coloradans are breathing healthy air.”

“When ozone levels are spiking on hot summer days, it’s important to know how to reduce health risks for yourself and your family,” said Schatz. “It doesn’t have to be this way: our air should be safer to breathe in the first place. Our state leaders need to continue to take strong action to reduce ozone-forming pollution.”

###