The Colorado Air Quality Control Commission adopted five priority toxic air contaminants (PTACs): formaldehyde, benzene, hydrogen sulfide, hexavalent chromium compounds, and ethylene oxide, under the January 2025 rulemaking hearing which is just one step in a series of actions required by House Bill 22-1244. This initiative is part of Colorado’s ongoing efforts to protect public health and the environment from the adverse effects of air pollution.

Background

House Bill 22-1244 was signed into law in June 2022, establishing requirements to develop an air toxics program and with that came the rulemaking hearing in January of 2025 where the Air Quality Control Commission established a regulatory framework under Regulation 30. This initial rulemaking sets five priority toxics. Future rulemakings are expected to further implement the statute’s requirements.

New Regulation 30 – Identification of Priority Toxic Air Contaminants (PTACs)

The recently finalized Regulation 30 identifies five priority contaminants: formaldehyde (combustion byproduct), benzene (oil and gas extraction, production, and storage), hydrogen sulfide (waste management, industrial and manufacturing operations), hexavalent chromium compounds (metal fabrication and plating), and ethylene oxide (medical sterilization and research/development). It should be noted that acrolein was formerly proposed and was replaced by formaldehyde in the final rule based on direct testimony at the rulemaking hearing in January 2025. The rule becomes effective on March 17, 2025. There will be future rulemakings to establish health-based standards for these PTACs.

Regulation 3 Proposed Toxic Air Contaminants Reporting Changes

HB22-1244 requires TAC reporting, and the Division is proposing associated regulation via proposed Regulation 3 and 7 changes at the April 2025 rulemaking hearing. It is anticipated that these requirements will be moved to Regulation 30 at a later date.

Revised reporting requirements are proposed to start for RY2025 with the first report including the revised requirements due June 30, 2026, and annually thereafter. Currently only Title V major and synthetic minor sources are required to report facility-wide TAC emissions to the Division.

The key changes being proposed include:

• Adding certain minor source categories to the reporting requirements.
• Requiring incidental criteria air pollutant (CAP) emissions above APEN thresholds to be reported with the TAC report.
  • Incidental CAPs include carbon monoxide (CO), nitrogen oxides (NO_X), volatile organic compounds (VOC), sulfur dioxide (SO₂), total particulate matter less than 2.5 microns (PM_2.5), and total particulate matter
    less than 10 microns (PM₁₀).
• Reporting data at an emission-unit level with some aggregation of sources allowed.
• TAC specific de minimis reporting thresholds.
• Major sources must still report federal hazardous air pollutants (HAPs) above zero, even if below de minimis reporting threshold.
• Use of EPA’s Combined Air Emissions Reporting System (CAERS) to streamline reporting for non-oil and gas sources.
• All oil and gas sources reporting emissions under Regulation 7 to the oil and natural gas annual emissions inventory reporting (ONGAEIR) system, must report TACs and incidental CAPs through the ONGAEIR system.
• Reporting exemptions of certain sources such as motor vehicles, office activities, small fuel-burning equipment below the de minimis thresholds, and other exemptions.

New Sources Proposed to Report TAC Reports

Minor Sources Reporting Under ONGAEIR. The Division is proposing to expand TAC and additional CAP reporting to all sources subject to annual ONGAEIR reporting.

Minor Sources of Non-Oil and Gas Sector Reporting. The Division is proposing to expand reporting requirements to select minor sources outside of the oil and gas sector. The proposed expansion includes minor sources using or emitting ethylene
oxide and those with industrial process emissions (except combustion emissions) of hexavalent chromium, nickel, or cadmium above proposed de minimis reporting thresholds.

Minor Sources Reporting to the EPA Toxic Release Inventory (TRI). Sources reporting under TRI will be required to submit a TAC report. According to the gap analysis report, among the 181 sources reporting to the EPA TRI program:

• 64 are classified as major sources
• 56 are classified as minor sources
• 43 are classified as synthetic minor sources
• 19 sources do not have an air program status
• 13 TRI facilities have multiple air program classifications

For the 75 sources (56 minor + 19 unknown), the TAC report will be a new requirement.

Regulation 3 Proposed Fee Increases

To account for the increased demands in reporting and permit writing, the Division is also proposing to increase fees associated with the systems in the table presented below.

TABLE 1

Upcoming and Future Rulemakings

In addition to the recently finalized TAC rules and proposed rules, the Division will be undertaking the additional future rulemakings per HB22-1244:

• July 2025- Establish 3 additional toxic monitoring sites.
• Jefferson County, El Paso County, Pueblo County, and/or Fremont County are the locations under consideration.
• December 2025- conduct a needs assessment for an air toxics permitting program for stationary sources.
• April 2026- develop and adopt health-based standards for PTACs and emission control regulations for new and existing stationary sources to reduce emissions of PTACs.
• Beginning September 2029 and at least every five years thereafter: determine whether to identify additional PTACs, whether to set acute exposure limits for PTACs, determine whether to revise the health-based standards.
• Beginning September 2030 and at least every five years thereafter: adopt emission control regulations for any new PTACs and determine whether to revise existing emission control regulations.

If you would like to discuss the proposed TAC requirements for Colorado and how they may impact your facility, please email Ashley V Jones in Trinity’s Denver office or call 720.638.7647