Colorado officials took the first steps Friday in adding new control measures around five priority toxic air contaminants produced by sources ranging from oil-and-gas drilling to wastewater processing to the sterilization of medical equipment.
By choosing the five priority toxics, the Colorado Air Quality Control Commission triggered a process that will lead to creation of health-based standards around the compounds in September and then approval of emission-control strategies in 2026. Environmental activists cheered a future in which contaminants create fewer health problems in long-polluted areas, while business leaders warned that AQCC members selected the quintet without any discussion of whether the toxins are feasible to control.
The five contaminants that soon will face new regulations and restrictions are:
- Formaldehyde, which stems from the fuel combustion of engines and industrial boilers and can cause respiratory issues and cancer;
- Benzene, which is emitted from oil-and-gas well sites and cement-manufacturing plants and can cause cancer and create problems for reproductive systems;
- Hexavalent chromium — a product of coal-fired power plants, machine manufacturing and solvents used in glass manufacturing that can cause cancer and respiratory ailments;
- Ethylene oxide, which is emitted through commercial sterilization of medical equipment and can impact nervous and respiratory systems; and,
- Hydrogen sulfide — a product of refineries, wastewater-treatment plants and asphalt-material manufacturers that may cause headaches, nausea and psychological disorders.
Strong push from north Denver area
Ean Thomas Tafoya is the Colorado state director for GreenLatinos.
Commissioners heard extensive testimony from governments and community groups in north Denver and Adams County saying that their neighborhoods near industrial areas and the Suncor refinery in Commerce City need protection from these specific contaminants. Not only did the AQCC agree to begin the regulatory process for those toxics emitted from stationary sources, but it encouraged officials to identify more priority toxics as resources allow in the coming years and regulate contaminants associated with mobile sources too.
With the designation, the Colorado Air Pollution Control Division can address gaps in the federal rules for contaminants, manage minor sources of pollution and reduce residents’ risk from exposure, said Amanda Damweber, APCD supervisor of air toxics regulations. Legislators launched the process by mandating the new regulations in a 2022 law, and Damweber said it will create a “paradigm shift” in the way the state assesses risks from certain compounds and then controls those risks.
“It was a great day for environmental justice and clean air,” said Ean Thomas Tafoya, state director for GreenLatinos, after the conclusion of the two-day rulemaking. “The Air Toxics Act has so many benefits going into the future, and now it’s starting to fall into place.”
No consideration of controllability
Christy Woodward is the regulatory affairs advisor for the Colorado Chamber of Commerce
Business and industry leaders warned, however, that AQCC officials, in approving the APCD’s proposal without the intense deliberation that’s marked other recent rulemakings, have launched a regulatory process without understanding its full impacts. The only significant change made by the commission was the substitution of formaldehyde for acrolein — two compounds that emanate from largely the same sources — among the five priority contaminants.
Groups including the Colorado Chamber of Commerce, Colorado Oil & Gas Association and American Petroleum Institute Colorado noted that there have been no discussions about how feasible or even possible it is to control the compounds on the priority list. Thus, they said it was difficult to assess the impact of the rules when the AQCC identified the contaminants before creating any health-based standards for air toxics or determining how possible it would be to reduce the toxics without job loss or untenable costs.
“The ability to control should inherently consider whether the costs of control are reasonable. The division should have conducted at least some level of control reasonability analysis,” said Christy Woodward, Colorado Chamber regulatory affairs advisor. “The Chamber isn’t asking for no regulations. We’re asking for regulatory certainty.”
One toxic air contaminant stirs major debate
At the center of that debate was Metro Water Recovery, which serves as the largest wastewater treatment organization between Chicago and Los Angeles and has a treatment facility in north Denver. Adding controls such as covers over extensive liquid stream areas to control hydrogen sulfide emissions would be “at best challenging and, at worst, infeasible” for customers throughout the metro area, said chief legal officer Emily Jackson.
Largely because of that scenario, commissioners spent more time debating the inclusion of hydrogen sulfide than any of the other priority contaminants. While Metro Water officials said they already have done extensive work to reduce the odors from the compound, north Denver residents complained that it causes headaches and nosebleeds and forces them to stay home from work.
Commissioner Tony Gerber, a professor of pulmonary medicine, argued that proponents of prioritizing the contaminant failed to show any causality between the specific emissions of hydrogen sulfide and their ailments. Although the compound is odorous, there is limited data on its dangers — it is not considered a hazardous air pollutant by the federal government — and tying it to health conditions via anecdotal evidence could be akin to tying vaccines to autism because of a handful of people who link the two, he said.
“There’s no harm in putting this in. But this is a slippery slope,” Gerber said. “And I just think we need to be very careful about that slope, because if it was about something else for which we believe the opposite — like vaccines — we would feel differently.”
Regulating toxic air could send message to loud communities
But Commissioner Jon Slutsky said that AQCC members needed to think beyond the boundaries of physical health as they debated ways to improve public health with the regulations and consider the mental health of community members asking for help. Fellow commissioner Elise Jones added that the inclusion of hydrogen sulfide in the first five air contaminants to undergo regulation also would send a signal to poorer, higher-minority and traditionally polluted areas like Commerce City that the state is listening to them.
“We as a state are putting a huge priority on writing environmental wrongs and prioritizing communities that have been disproportionately impacted,” Jones said. “We don’t have to sit here and say there’s causality; we can sit here and say there’s concern. And I think that’s important in building trust.”
In the end, most of the commission, including Gerber, agreed to list hydrogen sulfide as a priority toxic air contaminant in a straw poll that was taken. And they approved the final list of five contaminants as well as the recommendations for future consideration of contaminants unanimously.
A scientific technical working group will present to the AQCC next month on ideas for how to implement health-based standards for the priority contaminants, and then the APCD will begin drafting proposed rules for a September hearing. The AQCC is not required to adopt emission-control strategy regulations for the contaminants until April 2026.