On April 1, 2026, the U.S. Environmental Protection Agency (EPA) issued updates to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for the chemical manufacturing area source (CMAS) categories under the Clean Air Act (CAA).
These updates stem from the EPA’s required technology review of emission standards under CAA Section 112(d)(6). The agency estimates the changes will reduce hazardous air pollutants (HAPs) by 160 tons per year and volatile organic compound emissions by 1,582 tons per year. Notably, the EPA did not finalize the proposed category for chemical manufacturing using ethylene oxide, citing the need for additional time to consider comments and coordinate regulation across area and major sources.
Affected Source Categories
The EPA identifies the following nine NESHAP and industrial source categories that may be affected:
- Agricultural Chemicals and Pesticides Manufacturing.
- Cyclic Crude and Intermediate Production.
- Industrial Inorganic Chemical Manufacturing.
- Industrial Organic Chemical Manufacturing.
- Inorganic Pigments Manufacturing.
- Miscellaneous Organic Chemical Manufacturing.
- Pharmaceutical Production Manufacturing.
- Plastic Materials and Resins Manufacturing.
- Synthetic Rubber Manufacturing.
According to the EPA, these categories produce at least one of 15 HAPs posing the greatest risk to human health and encompass approximately 251 facilities subject to the standards. The update covers a range of emissions sources, including process vents, storage tanks, equipment leaks, transfer operations, wastewater, cooling towers, and heat exchangers.
Changes to Applicable Standards
Affected facilities are subject to generally available control technology (GACT) standards designed to reduce HAP emissions. Under the CAA, the EPA may establish GACT standards in place of maximum achievable control technology (MACT) standards applicable to major sources. The new revisions tighten several GACT standards, making some equal to the stricter MACT requirements.
The changes include:
- New leak detection and repair (LDAR) requirements for equipment leaks and heat exchange systems in organic HAP service.
- New standards for pressure relief devices and pressure vessels.
- New electronic reporting requirements.
- Continuous performance-testing requirements for nonflare air pollution controlling devices.
The EPA’s reasoning is that many CMAS chemical manufacturing process units operate similarly to major source facilities subject to the MACT standards. The agency notes that for some facilities, the purchase of new equipment and systems, updates to permits, and revisions to site guidance and operating procedures may be required.
Reporting and Compliance
Owners and operators must submit reports through the EPA’s electronic reporting systems. Compliance deadlines include:
- June 1, 2026 (performance-test results).
- August 31, 2026 (notification of compliance status reports).
- April 1, 2029 (periodic reports).
Facilities potentially subject to these updates should assess whether they fall within one of the affected source categories and evaluate the applicability of the updated requirements.
Effective Dates
Petitions for judicial review of this action must be filed in the U.S. Court of Appeals for the District of Columbia Circuit by June 1, 2026.
Existing sources that commenced construction or reconstruction between October 6, 2008 and January 22, 2025 must comply with the new amendments by April 1, 2029, or upon startup, whichever is later. New affected sources commencing construction or reconstruction after January 22, 2025 must comply by April 1, 2026 (the final rule’s effective date), or upon startup, whichever is later.
Our team is ready to assist you in evaluating applicability and addressing these changes.
If you have any questions, or would like additional information, please contact one of the attorneys on our Environment, Land Use & Natural Resources team.
You can subscribe to future advisories and other Alston & Bird publications by completing our publications subscription form.