Wildfire smoke and ground-level ozone combined to make it a difficult day to breathe across Colorado on Monday.
Smoke from fires burning in Colorado and in Utah inundated mountain valleys, leading to air quality graded moderate or worse across much of western Colorado. The Colorado Department of Public Health and Environment issued an air quality health advisory due to smoke for Grand, Gilpin, Clear Creek, Summit, Eagle, Garfield, Mesa, Delta, Pitkin, Lake, Park, Chaffee, Gunnison, Montrose, Ouray, San Miguel, Dolores and northern Montezuma counties.
“Moderate to heavy smoke impacts are currently being felt in communities such as Edwards, Aspen and Silverthorne,” the agency posted on its daily smoke blog. “The heaviest smoke is being reported in the valleys of Grand County, where Highway 40 is a smoky drive from Winter Park northward through Fraser and Granby to the shores of Grand Lake.”
Areas around Pueblo also reported poor air quality Monday morning, due to a fire that has forced the evacuation of the town of Beulah.
And, while the Front Range was largely smoke-free Monday morning, that could change as the afternoon winds and temperatures increase, allowing the fires to grow bigger.
“Smoke impacts are obviously expected in areas very close to the fires, but smoke will be transported downwind to the northeast and east-northeast,” the state posted on the smoke blog. “So although the air quality might be fine now in your neighborhood, be prepared for sudden changes Monday afternoon and evening.”
Meanwhile, CDPHE issued an air quality alert for the Front Range due to ozone and other pollutants. Ozone is formed when molecules related to fossil fuel activity — such as oil and gas production, driving gas-powered cars or using gas-powered yard equipment — bake in the hot sun on a still day. High ozone levels can worsen asthma, especially in children, or aggravate other respiratory and heart conditions.
This is the 13th ozone action alert day of 2026 along the Front Range. The ozone season typically runs from June through the end of September.
On bad-air days such as Monday, CDPHE advises people who are especially prone to breathing trouble to avoid prolonged time outdoors, especially if it is physically taxing, such as exercise. Children may also be uniquely vulnerable to poor-quality air because their lungs are still developing.