Colorado Public Protections From Toxic Air Contaminants

Colorado is implementing big changes for facilities emitting toxic air contaminants (TAC). In June 2022, the Colorado State Assembly passed HB22-1244 (Public Protections From Toxic Air Contaminants), which directed Colorado Public Health & Environment (CDPHE) to implement TAC reporting requirements and review potential pathways for additional air permitting for facilities emitting TAC. Additionally, HB22-1244 directed CDPHE to identify health-based benchmarks for five priority air toxic contaminants (PTAC).

TAC Emissions Reporting

The Public Protections From Toxic Air Contaminants law required CDPHE to collect emissions inventories for certain high-emitting facilities for the calendar years 2023 and 2024. These first two years were used to obtain data to inform regulatory changes around TAC permitting.

All facilities covered under an operating permit (i.e., Title V permit) or a synthetic minor facility permit are required to report calendar year 2025 emissions. A synthetic minor facility permit is one that contains enforceable emissions limits below the thresholds that would otherwise require an operating permit. Annual emissions reports for the 2025 calendar year must be submitted by June 30, 2026. Also new for the 2025 calendar year are exemptions and de minimis thresholds that apply to the annual emissions reports. The exemptions and de minimis thresholds are based on the type of facility and TAC emissions. Refer to CDHPE’s website or contact ALL4 for more information on exemptions.

Changes to Regulations 3 and 7 will require additional facilities to report for calendar year 2026. These facilities include all Oil and Natural Gas Annual Emissions Inventory Reports (ONGAEIR) sources and activities, and all facilities notified by CDPHE. Minor sources that meet the industrial process use or emissions thresholds based on use of TAC above a minimum reporting threshold and sources subject to air reporting requirements under the United States Environmental Protection Agency (U.S. EPA) Toxic Release Inventory (TRI) program will also be subject to reporting.

Priority Toxic Air Contaminants

In January 2025, CDPHE identified five PTAC:

• Benzene
• Formaldehyde
• Chromium compounds (hexavalent)
• Ethylene oxide
• Hydrogen sulfide

Health-based benchmarks were approved for each of the five PTAC in September 2025. A benchmark is used to identify levels at which health effects may be present and provide a basis for future regulatory action. CDPHE has prepared a report outlining a proposed air permitting program and the resources necessary to implement that program. In the report, CDPHE determined that a health risk-based approach was the best path forward to regulate TAC emissions through air permitting. Many states, including California and Oregon, use a health risk-based approach to regulate TAC and have proven frameworks that Colorado could emulate.

What’s Next?

A TAC permitting program would require legislative action by the Colorado General Assembly. The Colorado General Assembly is expected to review the report and decide on a permitting path (if deemed necessary) by April of 2026.

ALL4 has extensive experience helping facilities understand and comply with state air toxics programs and we can help you determine what you need to do next. Stay tuned for further updates on how this program progresses. In the meantime, if you have questions on the Colorado air toxics regulations and how they may affect your facility please reach out to Clayton Queen at cqueen@all4inc.com.