Colorado has three years to lower ground-level ozone pollution to meet federal standards, and this summer’s hazy skies — caused by oil and gas drilling, heavy vehicle traffic and wildfire smoke — are putting the state in a hole as it’s already logged more dirty air days than in all of 2023.
“Our state has taken a lot of steps to improve air quality, but you can see it in the skies, you can see it in the air, that we still have work to do,” said Kirsten Schatz, clean air advocate for the Colorado Public Interest Research Group.
Two months into the 2024 summer ozone season, the Front Range already has recorded more high ozone days than the entire summer of 2023. As of Monday, which is the most recent data available, ozone levels had exceeded federal air quality standards on 28 days. At the same point in 2023, there had been 27 high-ozone days.
The summer ozone season runs from June 1 to Aug. 31. However, the region encompassing metro Denver and the northern Front Range this year recorded its first high ozone day in May, and in some years ozone pollution exceeds federal standards into mid-September.
The region is failing to meet two air quality standards set by the Environmental Protection Agency.
The first benchmark is to lower average ozone pollution to a 2008 standard of 75 parts per billion. The northern Front Range is in what’s called “severe non-attainment” for that number, meaning motorists must use a more expensive blend of gasoline during the summer and more businesses must apply for federal permits that regulate how much pollution they spill into the air.
The second benchmark requires the region to lower its average ozone pollution to a 2015 standard of 70 parts per billion, considered the most acceptable level of air pollution for human health. In July, the EPA downgraded the northern Front Range to be in serious violation of that standard as the region’s ozone level now sits at 81 parts per billion. The state must now submit to the EPA a new plan for lowering emissions.
Colorado needs to meet both EPA benchmarks by 2027, or it will be downgraded again and face more federal regulation.
Of the 28 days the state has recorded high ozone pollution levels, 17 exceeded the 2008 standard of 70 parts per billion, according to data compiled by the Regional Air Quality Council, an organization that advises the state on how to reduce air pollution.
That’s bad news for the region after state air regulators predicted Colorado would be able to meet that standard by the 2027 deadline. The EPA calculates average ozone pollution levels on a three-year average, so this summer’s bad numbers will drag down the final grade.
“It’s not a good first year to have,” said Mike Silverstein, the air quality council’s executive director.
Smoke from wildfires near and far
Ground-level ozone pollution forms on hot summer days when volatile organic compounds and nitrogen oxides react in the sunlight. Those compounds and gases are released by oil and gas wells and refineries, automobiles on the road, fumes from paint and other industrial chemicals, and gas-powered lawn and garden equipment.
It forms a smog that can cause the skies to become brown or hazy, and it is harmful to people, especially those with lung and heart disease, the elderly and children. Ground-level ozone is different than the ozone in the atmosphere that protects Earth from the sun’s powerful rays.
Wildfire smoke blowing from Canada and the Pacific Northwest did not help Colorado’s pollution levels in July, and then multiple fires erupted along the Front Range over the past week, creating homegrown pollution from fine particulate matter such as smoke, soot and ash. Ultimately, though, the heavy smoke days could be wiped from the calculations from 2024, but that decision will be made at a later date.
Still, June also saw multiple high ozone days, and air quality experts say much of the pollution originates at home in Colorado and cannot be blamed on outside influences.
The out-of-state wildfire smoke sent ozone levels skyrocketing the week of July 21 to 27, Silverstein said, but it’s not the reason the numbers are high. The week prior saw ozone levels above federal standards, too, and wildfire smoke had not drifted into the region.
“Pull the wildfires out and we would probably still have had high ozone,” he said.
Jeremy Nichols, senior advocate for the Center for Biological Diversity, also warned that wildfires should not be used as an excuse for the region’s air pollution.
“While the wildfires are out of our control, there is a whole bunch of air pollution we can control,” he said. “I don’t want to let that cover up the ugliness that existed here in the first place.”
Nichols blames oil and gas drilling for the region’s smog. The state is not doing enough to regulate the industry, he said.
“We actually need to recognize we are at a point where oil and gas needs to stop drilling on high ozone days,” Nichols said. “Just like we’re told to stay home on high ozone days, business as usual needs to stop. I don’t think we’ve clamped down on them and in many respects they are getting a free pass to pollute.”
Legislation that would have prevented drilling on high ozone days failed during the 2024 session.
However, the air quality council has approved two measures to reduce emissions in the oil fields and is preparing to send those to the Colorado Department of Public Health and Environment for approval.
One proposal would require drilling companies to eliminate emissions from pneumatic actuating devices, equipment driven by pressurized gas to open and close valves in pipelines, Silverstein said. Oil companies already are required to make 50% of those devices emission-free, and the federal government also is requiring them to be 100% emission-free by 2035. But Colorado’s proposal would accelerate the timeline, he said.
The second proposal would tell companies to stop performing blowdowns, which is when workers vent fumes from pipelines before beginning maintenance to clear explosive gases, when an ozone alert is issued, Silverstein said.
“There are thousands of these very small events, but these small events add up to significant activity,” he said.
Gabby Richmond, a spokeswoman for the Colorado Oil and Gas Association, said the industry supports the new regulations. She said operators also were electrifying operations where possible and voluntarily delaying operational activities on high ozone days.
“Our industry values clean air, and we are committed to pioneering innovative solutions that protect our environment and make Colorado a great place to live,” Richmond said in a statement. “As a part of this commitment, we have significantly reduced ozone-causing emissions by over 50% through technology, regulatory initiatives and voluntary measures — all in the spirit of being good neighbors in the communities where we live and work.”
“Knock down emissions where we can”
Meanwhile, people who live in metro Denver and the northern Front Range are asked to do their part, too.
When the state health department issues an ozone action alert — which is a forecast for high pollution levels — people are asked to limit driving as much as possible. They also are asked to avoid using gas-powered lawn and garden equipment until later in the day when the sun starts dropping behind the mountains and temperatures fall.
It would be easy to blame Colorado’s ozone pollution on its geography, global climate change that is raising temperatures, and pollution blowing from other countries and states, Silverstein said. But Colorado has a responsibility to do its part.
“We have 4 million people and a big oil and gas field and lots of industrial activity and all of the things related to human activity all in one concentrated location with a great mountain backdrop, but it comes with a bit of a price,” he said. “So it’s up to us to find the strategies to knock down emissions where we can.”
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