Colorado environmental officials are about to adopt one of the most comprehensive state-level regulatory frameworks in the U.S. for chromium electroplating and anodizing operations.
On April 17, the Colorado Air Quality Control Commission says it will finalize revisions to Regulation 30, implementing new emission control requirements for hexavalent chromium under Part B, Section III.E.
Part of the proposal is to ban the installation of any new hexavalent chromium finishing lines. Existing shops will not be able to increase emissions after June 14. The new rules will target fugitive emissions, requiring enclosures, and mandate additional reporting.
For the estimated 26 plating and anodizing shops that the CAQCC says are in Colorado, the new rules represent a significant expansion beyond existing federal requirements under EPA’s NESHAP Subpart N, particularly in fugitive emissions control, building enclosure requirements, work practices, and reporting.
One of the most impactful changes is the requirement that all hexavalent chromium plating and anodizing tanks operate within a building enclosure.
The CAQCC says it will hear from affected businesses and industry at the hearing. The agency says it is basing its new regulations on those implemented by the California Air Resources Board (CARB) under its Airborne Toxic Control Measure for Chromium Electroplating and Chromic Acid Anodizing Operations.
In 2024, CARB imposed strict new rules on finishers that will effectively force the closure of many chromium-using metal-finishing operations.
Which Shops Will be Affected?
Covered operations include hard (functional) chrome plating, decorative chrome plating, and chromic acid anodizing. Colorado officials say they have determined that safer, technically feasible alternatives are available in the use of trivalent chromium.
The CAQCC compiled key compliance dates that show the requirement compliance and the deadline:
- Prohibition on new decorative hex chrome use: June 14, 2026
- Housekeeping & enclosure requirements: June 14, 2026
- Spray rinsing & compressed air restrictions: December 14, 2026
- Approved fume suppressants & surface tension limits: December 14, 2026
- Performance testing: April 15, 2027
- Annual compliance reporting begins: June 30, 2028
- Full enclosure of buffing/grinding areas (existing sources): June 14, 2028
Building Enclosures: A Major Shift
One of the most impactful changes is the requirement that all hexavalent chromium plating and anodizing tanks operate within a building enclosure.
Key enclosure provisions include:
- Tanks must be fully housed within a permanent, enclosed structure
- Openings on opposite ends of the enclosure may not be open simultaneously
- Openings facing sensitive receptors (homes, schools, healthcare facilities) within 1,000 feet must remain closed except for entry and exit
- Buffing, grinding, and polishing areas must be physically separated and, for existing sources, fully enclosed by June 14, 2028.
These requirements are intended to control fugitive emissions, which the CAQCC found were inadequately addressed by federal standards.
The CAQCC is also establishing enhanced housekeeping and work practices. Beginning June 14, 2026, facilities must implement extensive housekeeping measures designed to minimize the release and spread of hexavalent chromium dusts and mists. Those include:
- Closed storage and transport of chromic acid powders.
- One-hour spill containment or cleanup requirement.
- Weekly cleaning of contaminated surfaces using approved wet or HEPA-based methods.
- Daily cleaning within 20 feet of buffing and grinding areas.
- Strict controls on dripping parts, including mandatory drip trays.
- Spray rinsing of plated parts only within tanks or behind splash guards.
- Restrictions on compressed air drying near tanks.
Fume Suppressants: CARB-Aligned but More Stringent
Colorado has adopted a list of approved chemical fume suppressants aligned with California Air Resources Board (CARB) approvals, but with stricter surface tension limits than those in the federal NESHAP.
Facilities must use only listed or CARB-approved alternative suppressants, monitor and document surface tension, and maintain it below the specified dynes/cm thresholds. Those new compliance rules begin December 14, 2026
Facilities already using compliant suppressants may still need to tighten monitoring and recordkeeping practices to meet the new numeric limits.
Performance Testing Requirements and Recordkeeping
By April 15, 2027, all affected facilities must complete a performance test in accordance with the procedures in 40 CFR 63.344/347. While federal Subpart N generally requires only an initial test, Colorado is requiring updated testing to reflect current operations, newly required suppressants, and more stringent surface-tension standards. Testing results must be retained for five years and submitted to the CAQCC.
The CAQCC has added reporting obligations not found in federal rules, particularly for small and unpermitted facilities. Facilities must retain records for 5 years demonstrating compliance with housekeeping requirements, enclosure standards, and surface tension limits.
Electroplating and anodizing operations must also submit annual compliance reports beginning June 30, 2028, covering facility and ownership information, distance to nearest sensitive receptor, deviations and corrective actions, and certification of compliance with all applicable requirements.
The CAQCC says electroplating and anodizing operations can convert to trivalent chromium chemistry to avoid facing these regulations. Still, the agency estimates the cost of a trivalent conversion ranges from $119,900 to $359,700 per system. There are also higher costs associated with running trivalent systems.
“Trivalent chromium has higher operating costs, estimated at an additional $1.43 per kAmp-hr (2025 USD), compared to hexavalent chromium,” the agency writes in its report. “These conversion costs are partially offset by savings from no longer needing to comply with hexavalent chromium-specific rules, such as HEPA filter maintenance, source testing, building enclosure requirements, employee medical surveillance, and other waste management rules.”
The CAQCC, however, says it cannot estimate the amount of potential air pollution reductions that will occur if it passes these rules.
“Based on the exemptions for these sources historically offered from the Division's APEN and permitting programs, the current baseline annual emissions are difficult to quantify; the emission reductions from these strategies cannot be quantified in Colorado,” the agency says. “Given the high toxicity of this PTAC, any emission reductions from chromium plating and anodizing tanks, along with the additional reductions in fugitive emissions, are considered necessary for improving the health of communities surrounding these sources of hexavalent chromium emissions.”
