Record high temperatures and relatively stagnant air on the northern Front Range are pushing monitors for health-damaging ozone well past violations, and the accumulation of high readings ensure Colorado will fail a three-year averaging test to bring the choking gas below federal limits, local air quality officials said.
The 10 Front Range counties making up the ozone nonattainment area have already recorded 51 days above the Environmental Protection Agency cap of 70 parts per billion, with weeks left to go in the ozone danger season. Thirty-four of those days even spiked above the older, more lenient cap of 75 parts per billion. That compares with 23 total days above 70 ppb last year, when favorable winds and relatively cooler temperatures gave regional air officials some hope the counties could string together a couple of years attaining the limits.
Under the U.S. Clean Air Act, if the EPA determines Colorado has not made progress toward the ozone limits in averages taken from 2024 through 2026, the federal government can impose new sanctions. That could include expanding the number of industrial sources that need an air pollution permit, or restrictions on volatile paints and household cleaners and solvents that give off ozone precursors.
Even after allowances for out-of-state wildfire smoke Colorado can’t control, “now it appears that we can’t make it” for the three-year average, said Mike Silverstein, executive director of the Regional Air Quality Council, which makes policy recommendations to state and local regulators.
“We got some hope in 2025 that the strategy package that we had in place was going to really hit the mark,” Silverstein said, including programs to switch out highly polluting lawn and garden machinery with clean electric motors. “Our modeling from a couple years back indicated that we would be close, and that we had an opportunity to attain by 2026, but the data isn’t bearing that out.
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