Colorado air-quality regulators have identified five priority toxic air contaminants for which they will propose more stringent regulations, including ones emitted from combustion engines, medical-device sterilization processes and petroleum-refining activities.
The Colorado Air Quality Control Commission will hold a hearing in January to formally establish the priority air contaminants and then will hold another in September to set health-based standards for the pollutants. Another hearing in April will create new reporting requirements around these and other air contaminants that would mandate more frequent self-reporting from emitters on more compounds.
These new rulemakings stem from a 2022 law that sought to expand Colorado air-quality regulations beyond greenhouse gas emissions into other chemicals shown to cause higher risks of cancer or other health conditions. The rules will affect sectors facilities ranging from oil-and-gas drilling sites to the state’s lone petroleum refinery and from wastewater treatment plants to machinery- and glass-manufacturing plants.
“Our prioritization really focused on a risk-based approach, focusing on the compounds that carry the highest health risks,” said Amanda Damweber, air toxics regulation supervisor for the Colorado Department of Public Health and Environment, in an Oct. 16 presentation to the AQCC.
Why these contaminants were selected
The five contaminants that CDPHE staffers prioritized after a lengthy process that included ramped-up emissions reporting, public meetings and study of U.S. Environmental Protection Agency data are:
- Acrolein, a product of combustion from reciprocating engines, industrial boilers and residential wood burning that carries a high non-cancer health risk;
- Ethylene oxide, which poses the greatest cancer risk of any of the 142 air contaminants that CDPHE studied and is used in sterilization of medical equipment at facilities like the Terumo Blood and Cell Technologies plant in Lakewood;
- Hydrogen sulfide, a contaminant that is not listed as a federal hazardous air pollutant, but that CDPHE monitored for specifically in the north Denver/Commerce City area and discovered a high hazard quotient, Damweber said;
- Benzene, a contaminant produced in oil and gas extraction and in cement manufacturing that more than 1.4 million Coloradans are exposed to at concerning levels, more than half of whom are in disproportionately impacted communities; and,
- Hexavalent chromium, a byproduct of coal-fired power plants and machinery- or glass-manufacturing plants that carries a high cancer risk, also disproportionately in lower-income and higher-minority disproportionately impacted communities.
Pushback on several of the choices
Both AQCC members and one member of the north Denver community asked why formaldehyde — also a byproduct of combustion — was not included on the priority list. Staff said earlier in the meeting that it not only is the second most prevalent air contaminant reported in Colorado but ranks only behind chromium compounds in its distribution when weighted for toxicity.
Damweber responded that because formaldehyde is similar in its number of exposures to acrolein but carries a lower health risk, APCD officials chose not to list both in an effort to go after a greater breadth of contaminants with the new rules. The commission can consider new contaminants every five years and add an unspecified number to the list.
The one contaminant included on the list that brought immediate concern was ethylene oxide, which is used to sterilize nearly 20 billion medical devices annually — more than half of all devices made in a year — and has no substitute in many cases. Bobby Patrick, senior vice president of government affairs for device-manufacturing association AdvaMed, noted the EPA has new regulations on the chemical compound and urged the AQCC not to pass rules that could have negative implications on health.
“The responsible use of ethylene oxide is critical in the manufacturing process of medical devices,” Patrick said.
APCD staffers also are conducting a scoping exercise to set up a new toxic-air-contaminant permitting program that must be presented to the Legislature for consideration by December 2025, Damweber noted.
Increased reporting requirements for contaminants
In addition to adopting new health-based standards for the contaminants — standards that must be approved by the Legislature as well — the AQCC will hold an April rulemaking hearing to adopt more stringent reporting standards for facilities emitting the toxins. Some of the recommendations it presented this month include increasing the reporting frequency of certain sources, reducing emissions thresholds for reporting for higher-risk contaminants and expanding reporting to selected minor source types.
While both industry and members of the public expressed support for several aspects to the expanded reporting program, both groups also showed skepticism, Damweber said.
Community residents, for example, were dubious that the state should accept emissions reports from emitting facilities without layering on some sort of third-party oversight, she said. Industry leaders, meanwhile, balked at emission testing for the purposes of this new reporting and requested the state set minimum reporting thresholds for each pollutant.
Colorado is not the first state to require more reporting and rules around air toxins beyond EPA regulations; 16 other state air agencies require some kind of toxic-air-contaminant reporting, Damweber said. Some of them add extra state regulations to the full list of federally regulated contaminants — about 190 in total — and then create standards for pollutants that may be unique to their area.