State Begins Rulemaking on Priority Toxic Air Contaminants
Published on January 15, 2025
This week the Colorado Air Quality Control Commission (AQCC) will hold an important rulemaking hearing to address priority toxic air contaminants (PTACs). From Jan. 15–17, the AQCC will consider Regulation 30, a framework to guide Colorado’s new toxic air contaminant program. This rulemaking marks the beginning of a series of actions required by House Bill 22-1244, Public Protections from Toxic Air Contaminants.
What Are the Five Proposed Priority Toxic Air Contaminants?
The state has identified five priority toxic air contaminants to focus on:
- Acrolein (linked to tobacco smoke and wildfires)
- Benzene (found in vehicle exhaust and industrial emissions)
- Ethylene oxide (used in sterilization processes)
- Hexavalent chromium (from industrial processes like plating)
- Hydrogen sulfide (produced by industrial and natural sources)
Weld County has been actively participating in this process to ensure public health improvements are balanced with practical, achievable regulations. Dr. Annareli Morales, Weld County’s air quality policy analyst and a member of the technical work group, has been reviewing the framework used to identify these contaminants. Dr. Morales notes that the five substances under consideration were proposed directly by Division staff rather than the workgroup. “We never got a chance to discuss the Division's top 5 contaminants before they were presented to the public and proposed to the AQCC,” she said.
Notably, the inclusion of acrolein as a PTAC has faced opposition. Weld County, along with other stakeholders, has advocated for its removal, citing its limited controllability and the need for regulations that can effectively address exposure risks. In contrast, formaldehyde has emerged as a more robust candidate for inclusion as a PTAC by organizations like Adams County and Green Latinos.
Weld County’s Voice in the Process
In its official Rebuttal Statement, Weld County expressed key policy concerns, including the need for meaningful control strategies alongside PTAC designation. The county has underscored that formaldehyde, while measurable and well-characterized in terms of risk, should only be designated as a PTAC if control strategies for emission reductions are concurrently developed.
"We still believe the Commission must engage in simple good policymaking by directing the Air Pollution Control Division to consider each potential PTAC alongside respective control strategies so the state can achieve meaningful emission reductions,” Weld County stated in its rebuttal.
Additionally, Weld County highlighted the oil and gas industry's strides in reducing emissions, which, while not directly targeting PTACs, offer valuable co-benefits. This progress underscores the importance of ensuring that any new regulations are both evidence-based and achievable.
How You Can Participate
Public participation is an important part of the state rulemaking process. Here’s how you can make your voice heard:
- Learn About the Proposed Rules
Review the proposed rules and supporting arguments by exploring the public documents.
- Register for Public Comment
The AQCC website has instructions on how to register to speak during the public comment period on Jan. 15 at 4:30 p.m.
- Watch the Hearing
The hearing will be streamed online Jan. 16–17, beginning at 9 a.m. Details for participation and viewing are available on the AQCC website.