EPA's EtO NESHAP Reconsideration: What Commercial Sterilizer Operators Need to Know Before the May 15 Deadline
← Back to Blog Environmental

EPA's EtO NESHAP Reconsideration: What Commercial Sterilizer Operators Need to Know Before the May 15 Deadline

EPA's ethylene oxide sterilizer emissions rule reconsideration closes May 15, 2026. What operators must do to protect compliance—regardless of outcome.

by iSi Environmental

You Have 11 Days to Influence the Record on EPA’s Sterilizer Emissions Rule

If you operate a commercial sterilization facility or manage sterilization operations at a medical device, pharmaceutical, or contract manufacturing plant, you need to read this carefully. The EPA is reconsidering its 2024 ethylene oxide (EtO) emissions standards for commercial sterilizers—and the public comment period closes in approximately 11 days.

This is not an abstract regulatory debate. The stakes are direct: a $124,426 penalty per violation per day under the Clean Air Act, mandatory control equipment upgrades, continuous emissions monitoring systems (CEMS), and compliance deadlines already underway. Most sterilizer operators have missed the original May 1 comment deadline entirely. EPA extended it by 15 days specifically because industry requests revealed insufficient time for substantive response. That extension expires around May 15–16, 2026.

The outcome of this reconsideration could reshape your compliance obligations—but only if you understand what’s actually on the table and how to respond.

What EPA Proposed to Change (and What Actually Stays)

The Biden-era 2024 amendments to the Ethylene Oxide Commercial Sterilization NESHAP—formally adopted April 5, 2024—applied to the first time the EPA conducted a residual-risk and technology review (RTR) under Clean Air Act sections 112(d)(6) and 112(f)(2) on this source category. Those amendments tightened emission standards on previously regulated vent streams (sterilization chamber vents, aeration room vents, chamber exhaust vents) and brought previously unregulated room emissions into compliance via a permanent total enclosure (PTE) requirement (40 CFR 63.362).

On March 17, 2026, EPA published a proposed reconsideration (91 FR 12700, Docket EPA-HQ-OAR-2019-0178) with four main components:

1. The legal rescission argument. EPA proposes rescinding the section 112(f)(2) risk-based standards (the new aeration room vent and room emission rules) on the theory that section 112(f)(2) authorizes only one risk review per source category. If EPA prevails on this theory, the aeration room vent standard of 1 ppmv or 99% reduction (40 CFR 63.362) and the PTE requirement for room emissions could be withdrawn.

2. The aeration room vent standard revision. EPA also proposes modifying the aeration room vent standard even if the legal rescission argument doesn’t hold. This is important: if the rescission fails, you may still see changes to which facilities are covered (≥10 tons per year) and how the standard is applied.

3. Compliance demonstration changes. EPA is reconsidering requirements for CEMS (continuous emissions monitoring systems) and how facilities demonstrate they meet the standards. This directly affects your control equipment and monitoring costs.

4. Rescission of the PTE requirement. The permanent total enclosure requirement for room emissions—one of the most expensive 2024 rule provisions—is explicitly proposed for rescission.

What does NOT appear to be on the table: The sterilization chamber vent standard requiring 99% EtO reduction (40 CFR 63.362) for facilities using 1+ ton EtO per year. The reconsideration proposal is silent on this standard. Unless EPA subsequently proposes changes, the chamber vent standard remains in force.

Who Is Actually Affected: More Than Just Contract Sterilizers

The 2024 rule applies to commercial sterilization facilities defined by ethylene oxide usage rate, not by industry code. Coverage is triggered when:

  • A facility uses ≥1 ton EtO per year → sterilization chamber vent standard applies
  • A facility uses ≥10 tons EtO per year → aeration room vent and room emissions standards apply

This reaches beyond the obvious “commercial sterilizer” category. Medical device manufacturers, contract pharmaceutical sterilization operations, and captive sterilization at large manufacturing plants all fall under this definition if they cross the tonnage thresholds.

Approximately 88 commercial sterilization facilities nationwide are subject to the rule. Of those, 23 are flagged by EPA modeling as posing a lifetime cancer risk of 100-in-a-million or higher to surrounding communities—the level EPA considers unacceptable.

In iSi’s service region, two facilities are flagged as among the highest-risk in the nation:

  • Midwest Sterilization, Jackson, Missouri — One of the most heavily regulated EtO sterilizer sites in the country, subject to active EPA and Missouri DNR oversight. This facility is 1,204 Lenco Avenue, Jackson, MO.
  • Midwest Sterilization, Laredo, Texas — The single highest-emitting EtO sterilization facility in EPA’s current modeling. This facility operates under Texas Commission on Environmental Quality (TCEQ) permits and is a named focus of the EPA’s enforcement activity.

If you operate any sterilization equipment using EtO in the Midwest or South-Central US, expect scrutiny—regardless of how the reconsideration finalizes.

The Existing Compliance Requirements (What You Must Do Right Now)

Until EPA finalizes any amendment to the 2024 rule, the 2024 standards remain in full force and are enforceable. Here is what is binding today:

1. Emission Standards

For sterilization chamber vents (≥1 tpy facilities): Achieve ≥99% EtO reduction or route to a control device with equivalent performance (40 CFR 63.362).

For aeration room vents (≥10 tpy facilities): Achieve 1 ppmv or ≥99% reduction, whichever is less stringent (40 CFR 63.362).

For room emissions: Install and operate a permanent total enclosure (PTE) and route to a control device (40 CFR 63.362).

2. Continuous Emissions Monitoring (CEMS)

Install and operate a CEMS on covered vent streams for compliance demonstration (40 CFR 63.364). CEMS must be properly calibrated, maintained, and operated during all hours of EtO sterilization activity.

3. Compliance Schedule

The existing-source compliance clock began April 5, 2024. The first major milestone—April 5–6, 2026—applies to many facilities. Subsequent milestones extend through April 2027 (Tables 1–5 to 40 CFR 63 Subpart O).

Facilities that have already passed the April 2026 deadline must be in compliance now. The reconsideration does not stay or delay the enforcement of existing standards.

4. Reporting and Record Keeping

Maintain records and submit semiannual compliance reports (40 CFR 63.367). These reports document your compliance status and are the primary evidence EPA uses to assess whether you are meeting the standards.

The Enforcement Picture: EPA Is Still Focused

The fact that EPA is reconsidering this rule does not pause enforcement activity. EPA’s 2026 enforcement priorities explicitly list air toxics from commercial sterilizers as a focus area, and the source category sits inside EPA’s HEM-3 dispersion modeling track for facilities posing elevated cancer risk.

In 2022, EPA published a list of 23 high-risk facilities. This was the first wave of community notification. It was followed by direct EPA and state DNR engagement at the highest-emitting facilities—the Jackson, Missouri and Laredo, Texas Midwest Sterilization sites are the two leading examples of this targeted enforcement attention.

Current penalty figures are substantial and were adjusted for inflation effective January 8, 2025:

  • Civil judicial penalty (CJA § 113(b)): $124,426 per violation per day (40 CFR 19.4 Table 1)
  • Administrative penalty (CAA § 113(d)(1)): $59,114 per violation, capped at $472,901 (40 CFR 19.4 Table 1)

A single day of non-compliance on a major emission source generates five figures in civil exposure. A facility failing to install CEMS or achieve the 99% reduction standard can face penalties that accumulate daily.

EPA also retains criminal authority under CAA § 113(c) for knowing violations, including knowing endangerment liability for releases that place a person in imminent danger.

How to File a Substantive Comment (And Why It Matters)

Most comments EPA receives on reconsideration proposals are generic objections: “This standard is too strict” or “It’s not tough enough.” These comments do not influence the rulemaking record. EPA’s decision-making is grounded in specific evidence: cost data, technology limitations, lead times, site-specific conditions, and compliance history.

A substantive comment includes:

  1. Specific cost figures. If you have installed CEMS or control equipment, cite the actual cost and the timeframe required. If you face costs to achieve compliance, document them with vendor quotes or engineering estimates.

  2. Technology availability and lead time. Identify specific equipment (CEMS, thermal oxidizers, etc.) and the delivery/installation timeline. If key components have extended lead times, document this with supplier information.

  3. Operational impacts. Describe how compliance with the 2024 rule affects your sterilization throughput, facility operations, or product delivery. Quantify the impact if possible.

  4. Alternative compliance pathways. If you propose an alternative standard (e.g., a higher ppmv threshold, a different monitoring method), explain why the alternative protects public health while reducing burden.

  5. Site-specific conditions. If your facility has characteristics that affect compliance (enclosure design limitations, existing control equipment with limited flexibility), explain them with reference to site plans or engineering drawings.

Comments should cite the specific regulatory language you are addressing (e.g., “40 CFR 63.362(b)(1)”) and reference the Federal Register notice you are responding to (91 FR 12700).

File comments at Regulations.gov, Docket EPA-HQ-OAR-2019-0178 by approximately May 15–16, 2026.

The “Two Rulebooks” Problem: Documenting Compliance Decisions

Here is a practical risk that many sterilizer operators are overlooking:

You are legally bound by the 2024 rule today. If you have deferred compliance investments based on speculation about the reconsideration, you are accumulating exposure with each passing day. If EPA finalizes weaker standards (rolling back the 99% chamber vent requirement, eliminating the PTE requirement, etc.), those compliance investments become stranded costs. But the question arises: can you later use those sunk costs as justification for a modified compliance schedule at the state air-permit level?

The answer is yes—if you document your compliance decisions properly.

When you make a compliance investment under the 2024 rule (installing CEMS, building a PTE, installing control equipment), document:

  1. The decision date — when you committed to compliance
  2. The regulatory standard you were meeting — cite the specific CFR section
  3. Cost and timeline — what you spent, when completion occurred
  4. The compliance status as of today — whether you are currently in compliance, behind schedule, or in a phased rollout

This documentation becomes your defense in two scenarios:

Scenario A (favorable to you): EPA finalizes rollbacks. You have documented evidence that you invested in compliance in good faith under the 2024 rule. When you apply for a Title V minor source review modification later (e.g., to remove the PTE requirement after EPA’s rollback), you can point to your compliance history and negotiate a transition period with the state.

Scenario B (less favorable but manageable): EPA keeps the 2024 rule. You have documented your compliance status and can demonstrate good-faith effort, which protects you in the event of an inspection or enforcement action.

Either way, contemporaneous documentation is your strongest defense.

State-Level Implementation: The Reconsideration Will Flow Through Your State

iSi’s primary service region includes five states. In all five, the federal NESHAP standard is the binding floor:

  • Missouri (10 CSR 10-6.075) — Missouri DNR implements Subpart O under SIP delegation. No state-level EtO standard more stringent than federal.
  • Texas (30 TAC Chapter 113) — TCEQ implements through the federal delegation table. No state-level overlay tighter than federal.
  • Kansas (K.A.R. 28-19) — KDHE Bureau of Air implements 40 CFR 63 by reference. Federal standard applies directly.
  • Oklahoma (OAC 252:100) — DEQ implements via reference to the federal NESHAP. Federal standard applies.
  • Nebraska (Title 129) — NDEE administers by federal delegation. Federal standard applies.

Key point: Once EPA finalizes any amendment, it automatically flows to the state-implemented programs. You do not get a separate state comment period or state reconsideration process. The federal outcome is the state outcome.

Your Next Steps: An 11-Day Action Plan

By May 8, 2026 — Determine your facility’s applicability to the rule. Do you use ≥1 ton EtO/year? If yes, you are covered. Do you use ≥10 tons/year? If yes, the aeration room vent and room emission standards apply to you.

By May 10–12, 2026 — Gather your compliance documentation:

  • Current CEMS data (if installed)
  • Control equipment cost estimates and lead times
  • Site plans showing existing enclosures and emission sources
  • Sterilization process flowsheets
  • Any correspondence with state air permitting or EPA

By May 13–14, 2026 — Draft your comment. Use the substantive guidance above. Keep it focused and cite specific CFR language and cost data. If you do not have cost estimates, describe the operational impact in detail.

By May 15–16, 2026 — File your comment at Regulations.gov. Keep a copy for your files.

After May 15, 2026 — Continue compliance with the 2024 rule. Do not delay compliance investments betting on a favorable reconsideration outcome. The 2024 standards remain enforceable and penalties accrue daily for non-compliance.

How iSi Can Help You Navigate This

The intersection of aggressive EPA enforcement and a pending reconsideration creates a narrow window for documented compliance decisions and substantive regulatory response. Most sterilizer operators are either ignoring the reconsideration (and accumulating compliance debt) or planning for a rollback that may not happen.

iSi’s approach is different. We help operators:

  • Document your facility’s current emissions and control status — baseline air quality data and equipment specifications that inform compliance feasibility
  • Evaluate which 2024 standards apply to your operation — not all facilities are subject to all provisions; applicability depends on tonnage and source category
  • Draft substantive comments grounded in your actual costs and technology constraints — if you choose to file, your comment carries weight because it cites your facility’s specific data
  • Develop a two-path compliance strategy — compliance work that succeeds under the 2024 rule AND accommodates the possibility of rollbacks, so sunk costs don’t become stranded costs
  • Prepare for the enforcement environment — EPA’s 23 high-risk facilities are under active scrutiny; if your site is in that group or nearby, proactive compliance and documentation now prevents larger problems later

The 11-day comment window is narrow, but it’s the last meaningful opportunity to influence the rulemaking record. Waiting for the final rule and then reacting is the path to compliance penalties and emergency remediation.

If your sterilization operation uses ethylene oxide in the Midwest or South-Central US, talk to us. We’ve guided facilities through the 2024 rule implementation and we understand both the technical requirements and the enforcement environment.

Sources

Tags: