EPA Fine-Tunes Factory Fumes: Polyols Get Emission Overhaul
Published Date: 3/18/2026
Rule
Summary
The EPA is updating rules for factories that make polyether polyols, chemicals used in lots of products. These changes focus on cutting harmful ethylene oxide emissions, improving testing every five years, and switching to electronic reporting. The new rules start March 18, 2026, and will help protect the air while keeping industry on track without big cost surprises.
Analyzed Economic Effects
8 provisions identified: 0 benefits, 7 costs, 1 mixed.
Stricter EtO Process-Vent Controls
For process vents and storage vessels in EtO service, owners/operators must either route emissions through a closed vent to a non-flare control device that reduces EtO by ≥99.9% by weight or to a concentration less than 1 ppmv for each process vent/storage vessel, or route to a flare that meets new operating and monitoring requirements. As an alternative for process vents, the rule retains an option of an annual combined limit of 5 pounds per year for all combined process vents.
EtO-Specific Standards Finalized
The EPA finalized ethylene oxide (EtO) specific standards for the polyether polyols production industry covering process vents, storage vessels, equipment leaks, heat exchange systems, and wastewater. These EtO-specific standards are finalized under Clean Air Act section 112(d)(6) and the final rule is effective March 18, 2026.
Heat-Exchanger Leak Monitoring Tightened
Owners/operators must conduct quarterly monitoring for heat exchange systems (after an initial six months of monthly monitoring if not already done) using the Modified El Paso Method and repair leaks at or above 6.2 ppmv (as methane) of total strippable hydrocarbon concentration. For heat exchangers "in ethylene oxide service" (process fluids that are 1.0 percent or greater by weight EtO) the rule requires monthly monitoring and repairs as soon as practicable but no later than 45 days after receiving results, and repairs cannot be delayed more than 30 days if monitoring shows 62 ppmv or higher.
More Storage Tanks Now Need Controls
The rule lowers the Group 1 storage vessel size threshold so existing and new storage vessels between 38 cubic meters (10,000 gallons) and 151 cubic meters (40,000 gallons) with vapor pressure ≥ 6.9 kPa must add controls. The EPA also requires upgraded deck fittings and guidepole controls for all storage vessels equipped with an internal floating roof (IFR).
Tighter Monthly Leak Monitoring Rules
The EPA finalized more stringent leak monitoring for equipment in EtO service: connectors in gas/vapor and light liquid service and valves in gas/vapor or light liquid service must be monitored monthly at a leak definition of 100 ppmv with no reduction in monitoring frequency and no delay of repair. Light-liquid pumps must be monitored monthly at a leak definition of 500 ppmv.
Regular 5-Year Testing and Electronic Reporting
The final rule requires performance testing once every five years to show compliance with emission limits for certain process vents if emissions are routed to a control device other than a flare. It also requires electronic reporting via the EPA Central Data Exchange (CDX) using the Compliance and Emissions Data Reporting Interface (CEDRI) for performance test reports, flare management plans, and periodic reports.
EtO Wastewater Standards Finalized
The EPA finalized EtO-specific requirements that apply to wastewater from PEPO production as part of the EtO-specific standards covered under section 112(d)(6). These finalized wastewater provisions target emissions related to EtO in wastewater streams at PEPO facilities.
Rule Affects About 23 Facilities
As of December 1, 2025, the EPA identified 23 polyether polyol production facilities that are subject to the PEPO NESHAP and thus to these final amendments. If you operate one of these facilities, the finalized requirements (effective March 18, 2026) apply to you if your processes meet the NESHAP applicability criteria.
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