2026 Chemical Sector Lookahead

At the end of 2024 there were numerous regulatory developments impacting the chemical manufacturing industry. For many, it felt like a nonstop stream of changes that were going to significantly impact the legacy compliance programs of their facilities. In 2025, with the change in administration, the U.S. Environmental Protection Agency (U.S. EPA) shifted to a deregulatory focus. However, with the full agenda and the government shutdown, not many of the stated deregulatory priorities were achieved in 2025. Now that we are entering 2026, we are expecting to see progress in the form of proposed and final rules that will scale back or remove completely the changes that were completed during the previous administration. Additionally, there remain some consent decree driven deadlines that U.S. EPA must meet that will have impacts on the industry. This lookahead article briefly touches on several of the more significant actions we expect the agency to take in 2026.

PEPO, CMAS, HON

What’s on the horizon for chemical sector air regulations in 2026? As of the writing of this article the course ahead is still a little foggy, but we expect that fog to somewhat recede early this year whenU.S. EPA finalizes changes to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Chemical Manufacturing Area Sources (CMAS) on February 27, 2026. Shortly after, U.S. EPA is expected to finalize changes resulting from a risk and technology review (RTR) for the NESHAP for Polyether Polyols Production (PEPO) on March 13, 2026.

U.S. EPA initially proposed significant changes to the PEPO rule on December 27, 2024 to address perceived risk from ethylene oxide (EtO), incorporate updates in technology, and address regulatory gaps. On January 22, 2025, U.S. EPA proposed changes to the CMAS rule. Like the PEPO proposal, U.S. EPA proposed changes to regulate emissions of EtO, address developments in technology, revise testing and reporting requirements, and remove affirmative defense provisions. Both of these proposals followed in the wake of U.S. EPA’s sweeping changes to the NESHAP for Synthetic Organic Chemical Manufacturing Industry (SOCMI) and Group I and II Polymers and Resins (P&R I and II) Industries (known as The HON and P&R I and II) that were finalized on May 16, 2024. U.S. EPA heavily referenced the new and revised provisions in the HON rule to incorporate these proposed changes into the PEPO proposal, and to a lesser extent, the CMAS proposal.

As we previously summarized in the PEPO/CMAS article linked above, both the PEPO and CMAS proposals contained new emissions standards for EtO from sources such as process vents, equipment leaks, storage tanks, heat exchange systems, and wastewater. Both proposals also contained fenceline monitoring provisions for EtO by reference to the HON rule. Individual companies and industry associations submitted numerous comments on the proposed EtO control standards during each respective comment period. Commenters also provided U.S. EPA with input on several non-EtO related portions of the proposed rule. Although we expect to see several differences from proposal to final, we won’t speculate on them here. Expect to see another article in about a month or so with details on the final CMAS rule and insights on the upcoming final PEPO rule.

We also expect U.S. EPA to issue a proposed reconsideration rule for several aspects of the 2024 HON updates sometime in mid-2026. Multiple industry associations and individual companies submitted petitions requesting U.S. EPA reconsider the use of the EtO Integrated Risk Information System (IRIS) value, the risk assessment methodology, the fenceline monitoring requirements, EtO control requirements, startup and shutdown provisions, the removal of the total resource effectiveness concept, and several other provisions. Because of the overlap between the HON and PEPO rules, we expect that the upcoming PEPO final rule will provide a reasonable prediction of the changes to expect in the HON reconsideration proposal. The reconsideration proposal included additional requests for the SOCMI New Source Performance Standards (NSPS, Subparts IIIa, NNNa, RRRa) and P&R II, but it remains unclear how U.S. EPA plans to address those requests or if we will see a reconsideration proposal in 2026.

As a reminder, facilities subject to the EtO provisions of the final HON rule must be in compliance with those requirements no later than July 15, 2026. Additionally, facilities subject to the fenceline monitoring requirements in the HON must start collecting data by July 15, 2026, although the requirements to implement corrective actions do not apply until July 2027. Keep in mind that even though we may see a proposed HON reconsideration rule from U.S. EPA by July of this year, a final rule is still another several months away after the proposal.

NSPS Kc

We also expect to see a proposed reconsideration rule for the Standards of Performance for Volatile Organic Liquid Storage Vessels (Including Petroleum Liquid Storage Vessels) for Which Construction, Reconstruction, or Modification Commenced After October 4, 2023 (40 CFR Part 60, Subpart Kc). The original rule was published on October 15, 2024 and contained several changes compared to Subpart Kb, the legacy New Source Performance Standard (NSPS) applicable to volatile organic liquid storage tanks. We detailed those changes in a previous article, but most notable was U.S. EPA’s revised interpretation of a modification as it applies to storage vessels, new air emissions control requirements, degassing requirements for certain tanks, and a variety of new inspection, monitoring, performance testing, and recordkeeping requirements.

A petition for reconsideration was submitted by industry in December 2024 and U.S. EPA granted reconsideration in April 2025. The petition covered items such as the definition of modification, control requirements for both internal and external floating roof tanks, and clarifications around degassing requirements, to name a few. We expect U.S. EPA to issue a proposed reconsideration rule addressing the petitioners’ concerns in the spring of this year, but those facilities with tanks subject to Subpart Kc must continue to comply with the provisions as they currently stand until U.S. EPA finalizes the reconsideration rule, which we expect to occur sometime in 2027. If you have questions on applicability or how to comply with Subpart Kc in the meantime, check out the “frequently asked questions” page published by U.S. EPA in April 2025, or reach out to your ALL4 project manager or Philip Crawford at pcrawford@all4inc.com.

HWC MACT

U.S. EPA proposed revisions to 40 CFR Part 63, Subpart EEE: NESHAP from Hazardous Waste Combustors (HWC MACT) on November 11, 2025. We discussed U.S. EPA’s proposed changes in an article published earlier this month. The changes included an emissions limit for hydrogen fluoride (HF) for solid fuel boilers and work practices to limit HF from liquid fuel boilers. U.S. EPA also proposed hydrogen cyanide (HCN) limits for solid and liquid fuel boilers, as well as cement kilns. The proposed revisions also include replacement of the startup, shutdown, and malfunction (SSM) exemption with work practice standards for periods of SSM; electronic reporting requirements; and an allowance for states to exclude HWC that are considered area sources from the requirement to obtain a Title V permit if the facility’s Resource and Conservation Recovery Act (RCRA) permit is revised accordingly. While the impacts of the proposed changes are expected to be minimal, entities who are operating HWC MACT applicable sources should spend time understanding the potential implications of the proposed changes and watch the final rule closely to verify they will be able to comply with the final requirements. We expect to see the final rule published sometime in 2026.

Other Updates

The Risk Management Program (RMP) rule was originally issued in 1996. Substantial changes were proposed and finalized in 2017 but were rolled back in 2019. Changes were once again proposed in 2022 and finalized in March 2024. The proposed updated RMP rule was recently reviewed by the White House Office of Management and Budget (OMB) so we will see it any day now. We expect that the revised rule will be closer to the 2019 version of the RMP rule than the 2024 version, given the current administration’s lack of focus on the environmental justice and climate change issues that prompted many of the recent revisions.

The 2024 changes to the rule that reversed the once in, always in policy, or “Reclassification of Major Sources as Area Sources Under Section 112 of the Clean Air Act” (MM2A) Rule, were eliminated in 2025 through a Congressional Review Act (CRA) resolution and a recent Federal Register notice officially reverted the rule to its 2020 form. Original litigation on the 2020 MM2A rule had been halted upon completion of the September 2024 final rule. With the CRA signed and that rule no longer in effect, litigation on the 2020 MM2A rule is now moving ahead. It’s not clear what the results of that litigation will be, but we are continuing to monitor this regulation. Currently, under the 2020 MM2A rule, major sources of hazardous air pollutants (HAP) can reclassify to area source status if their emissions are below the HAP major source thresholds.

In December 2024, U.S. EPA finalized risk management rules for three chemicals under the Toxic Substances Control Act (TSCA): Carbon Tetrachloride (CTC), Perchloroethylene (PCE), and Trichlorethylene (TCE). U.S. EPA has since indicated they are reconsidering at least some aspects of each of these rules – accepting public comment for CTC and PCE reconsideration and TCE extending compliance dates for two use cases. In the case of both CTC and PCE, U.S. EPA has already said that this is just the first step in their efforts to reconsider, and possibly revise, the risk management rules. The impacts of a typical Risk Management Rule are near total ban of chemical manufacture or import, phase down of “essential” uses, and implementation of Workplace Chemical Protection Program (WCPP). We will be watching the reconsideration of these recent TSCA risk management rules to see what changes U.S. EPA proposes.

If you’d like to learn more about TSCA updates, see the our article U.S. EPA Seeks Public Comment on Updated Draft Formaldehyde Risk Calculation Memorandum to Inform Risk Evaluation under the Toxic Substance Control Act. In addition to the items discussed in this article, ALL4’s lookahead article series includes information on other relevant topics, such as the Clean Water Act Hazardous Substances Facility Response Plan Rule, Resource Conservation and Recovery Act (RCRA) updates, and changes expected from the Occupational Safety and Health Administration (OSHA). ALL4 has staff in our Environmental, Health, and Safety (EHS) practice that can help you understand the implications of each of these areas.

Conclusion

With any of the changes on the horizon, there is likely to be litigation, so it will take time to see what regulatory updates are permanent. ALL4 has a large and experienced air quality consulting practice, and we continuously monitor federal and state air regulatory developments and participate in industry association advocacy efforts. Our EHS experts also monitor changes to the non-air regulations that impact the chemical industry. We can help you comment on regulatory proposals and draft policies, evaluate how regulatory changes could affect your facility, strategize on how to implement new regulations or permit projects, navigate permit changes to your facility, implement new regulations and permit requirements, and track ongoing compliance with requirements. Please reach out to your ALL4 project manager, Philip Crawford, or Julie Taccino with any questions or if you need EHS consulting support.