Metro Denver and the northern Front Range this summer documented one of the worst ozone pollution seasons of the past 30 years, jeopardizing the region’s standing under federal air quality standards and possibly placing a higher financial burden on businesses.
The nine-county region logged 66 days during which ozone pollution exceeded federal standards, according to data compiled by the , a quasi-governmental agency focused on solutions to Colorado’s air pollution problem.
The region also logged 66 high ozone days in 2012, and its worst year was 2021, when it marked 67 high ozone days, according to , which goes back to 1995.
Mike Silverstein, the Regional Air Quality Council’s director, said wildfire smoke contributed to the 2026 ozone pollution problem but was not the sole reason levels were high this summer. Even if the council subtracted the days that smoke clouded the skies, the number would still be too high, he said.
“We have a homegrown problem that smoke only exacerbates,” Silverstein said.
The summer’s poor air quality could lead the to downgrade the northern Front Range’s standing to an “extreme” failure to meet federal air quality standards as defined by the Clean Air Act. That downgrade, which could happen after July 2027, would lead to higher fees assessed to industrial polluters to pay for programs aimed at improving the region’s air quality.
Metro Denver and the northern Front Range are now designated as being in “severe non-attainment” of those federal standards.
The region’s continued failure to control its ground-level ozone pollution also causes people — especially those with lung diseases such as asthma, elderly people and infants — to get sick, driving up health care costs.
“The health burden of air pollution is not evenly shared among us,” said Nick Torres, advocacy director for the American Lung Association of Colorado. “Let’s be clear — breathing air pollution is harmful to everyone. But some people are more at risk of illness and even death from their exposure.”
The lung association last year in the United States for ozone pollution, he said. More than 400,000 people in the metro area suffer from asthma and another 200,000 suffer from cardiovascular disease, and high ozone levels impact their overall health.
Ground-level ozone pollution forms on hot summer days when nitrogen oxides and volatile organic compounds — both of which are created by burning fossil fuels — bake in the bright sun and smother the region. That blanket of chemicals traps heat close to the Earth, raising temperatures and making it hotter and more difficult for people to breathe.
Colorado’s ozone season lasts from mid-May to mid-September.
The state’s mountains and weather patterns create a challenging environment for controlling ozone pollution, and wildfires contribute to it because they send fine particles into the air. But experts say the problem is made worse by the millions of cars on the state’s roads, oil and gas drilling, and industrial pollution.
Colorado has struggled to control its ozone pollution for decades, and it is out of compliance with two federal air quality standards.
The first standard is from 2008, by which time the state was supposed to lower its average ozone pollution level to 75 parts per billion. It has never met that standard and is considered in severe non-attainment, which means motorists pay for a more expensive blend of gasoline in the summer and more companies are required to apply for federal air pollution permits, which are more expensive and come with more regulations.
Colorado has also failed to meet the more stringent 2015 standard of 70 parts per billion. The EPA lists Colorado as in serious non-attainment for that standard. However, state officials last year asked the EPA to downgrade that status to severe ahead of schedule because the state does not expect to meet its next deadline for the 2015 standard.
The EPA uses a formula, based on average daily ozone readings, and calculates them over a three-year period to grade a region’s air quality, and Colorado is supposed to meet its next benchmark for the 2008 standard in early 2027. But the past three years of data indicate another failure could be coming.
However, Katherine Jenkins, a spokeswoman for the EPA’s Region 8, which includes Colorado, said a downgrade is not automatic under the Clean Air Act. There are only three regions in the United States — all in California — that are as being in extreme violation.
Colorado’s 2024 ozone season recorded 41 high ozone days, which was among the worst in a decade. Then a mild summer in 2025 gave regulators some hope because there were just 23 high ozone days, making it one of the better years on record.
But 2026, with its record-high average temperatures, nearly tripled the number of bad ozone days. Forty-two of those days exceeded the 75 parts per billion standard and 24 were above 70 parts per billion, data shows.
“It was a very difficult year,” Silverstein said. “We thought if we had clean data for this year for 75 parts per billion we could get into compliance.”
Solutions for lowering ozone pollution include reducing the cars and trucks on the roads by encouraging people to use public transportation and pushing more people to use electric vehicles; reducing emissions from oil and gas drilling and from other industries that pollute; and asking people to use electric lawn and garden equipment, Silverstein said.
At a news conference about poor air quality on Sept. 1, Torres said Colorado cannot expect help from the Trump administration in regulating polluters and called on state officials to do more to protect public health.
“Solutions are not coming from the federal government,” he said. “Rather, actions to weaken, delay and eliminate protective policies are putting the profit-driven interests of polluters above the health of everyday people, threatening to increase air pollution for Coloradans and people all across the country.”
Kirsten Schatz, an advocate for the , a consumer advocacy group, said the state’s leaders cannot ignore the pollution coming from tailpipes, oil and gas drilling, and gas-powered equipment.
“This summer has been a stark reminder that we have a homegrown air pollution problem that’s not going away on its own,” she said. “Our state leaders need to use all the solutions available to ensure our air is safe to breathe.”
