2026 Ozone Season Data Shows Poor Summer Air Quality in Denver Metro/North Front Range Nonattainment Area

Media contact: Jenn Fields, media and communications specialist, jfields@raqc.org, 303-502-7342

Front Range residents experienced 66 days this summer with concentrations of ground-level ozone that exceeded the federal standard, placing the 2026 ozone season among the most challenging since 2000, according to analysis from the Regional Air Quality Council (RAQC).

Consistently hot, sunny, stagnant weather this summer contributed to the frequent build-up of ozone pollution throughout the season. Wildfire smoke was also a prevalent air quality issue in Colorado this summer, and ozone precursors in wildfire smoke contribute to ground-level ozone formation. Analysis of air quality data using RAQC’s Smoke IMpact Assessment System (SIMAS) suggests a moderate to high likelihood that smoke contributed to increased ozone on certain days this summer. But while the impact of wildfire smoke was significant, the region experienced many ozone exceedance days this summer independent of wildfire smoke, and monitoring data shows that the region was out of compliance with the ozone standard regardless of smoke.

Ground-level ozone is an invisible, odorless pollutant that forms when emissions from many local sources — including industrial activity, transportation, and gas-powered lawn equipment — bake in the heat and sunshine during Colorado’s long summer days. Ozone is harmful to inhale even at relatively low levels; it irritates airways and causes inflammation, stressing the cardiovascular system and lungs. Long-term exposure is associated with increased chronic respiratory problems. People with asthma, older adults, and people who are active outdoors, especially outdoor workers, are at high risk of both acute and long-term impacts. However, children are at the greatest risk because their lungs are still developing, and they are more likely to be active outdoors when ozone levels are high.

The health burden of ozone pollution for residents of the Denver Metro/North Front Range ozone nonattainment area is high. A health impact assessment completed by researchers at the Colorado School of Public Health earlier this year found that by meeting the 70 parts per billion (ppb) federal ozone standard over the next five years, communities in the nonattainment area could save an estimated $211 million to $580 million annually in costs related to the health burden of ground-level ozone. Researchers’ analysis of health impacts on Coloradans included asthma-related visits to the emergency department, respiratory hospitalization, minor restricted activity days, and non-accident mortality, as well as the associated costs.

“Continued noncompliance with the ozone standard has a significant impact on our health and economy in Colorado,” said Mike Silverstein, executive director of the RAQC. “That’s why we’re working diligently to develop strategies that will reduce ozone pollution for residents of the Front Range and bring us into attainment with the ozone standard.”

2026 ozone season exceedances

Colorado’s official ozone monitoring sites record data year-round, but most ozone exceedances take place between mid-May and mid-September. The RAQC tracks days when ozone pollution reaches levels above federal ozone standards set by the Environmental Protection Agency.

• A total of 66 days in 2026 were in exceedance of the 70 ppb ozone standard, which was set by EPA in 2015.
• Of those 66 days, 42 days were also in exceedance of the 75 ppb federal standard, which was set in 2008 and is still in place in the region.
• Since 2000, the only year with a higher number of exceedance days was 2021, when the region experienced 67 days that exceeded the 70 ppb ozone standard.

2026 Ozone Action Day Alerts

The Colorado Department of Public Health and Environment (CDPHE) issues Ozone Action Day Alerts when meteorological conditions are favorable for the formation of ground-level ozone. However, action days do not always result in an ozone exceedance. CDPHE called a total of 63 Ozone Action Alert Days in 2026. Sign up for air quality alerts at Colorado.gov.

In addition to the state’s alerts, the RAQC’s Simple Steps. Better Air. public education program issues alerts on ozone action days with tips for Coloradans who wish to protect their health and reduce their emissions. Know when it matters most: Get alerts by texting “BetterAirCO” to 21000 for text alerts or sign up for email alerts at simplestepsbetterair.org/sign-up/.

About the Regional Air Quality Council

Established in 1989, the Regional Air Quality Council (RAQC) is designated by the governor as the lead air quality planning organization for Colorado’s Front Range. The RAQC works with state agencies to create plans to improve air quality and run programs that benefit the Front Range. We serve a nine-county region that is out of compliance with federal standards for ground-level ozone that includes Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, most of Larimer, and Weld counties.