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EPA proposes rule to reduce ethylene oxide emissions from commercial sterilizers

EPA proposes rule to reduce ethylene oxide emissions from commercial sterilizers

On April 11, 2023, the U.S. Environmental Protection Agency (EPA) proposed to update Clean Air Act (CAA) standards for ethylene oxide (EtO) emissions from commercial sterilizing facilities. Ethylene oxide—a flammable, colorless gas and one of 188 hazardous air pollutants regulated by the EPA—is used to sterilize medical devices and equipment, decreasing the risk of infection to healthcare providers, patients, and other consumers. However, it is suspected to be harmful when inhaled. If the regulation is approved as currently proposed, the EPA estimates that EtO emissions will be reduced by 80 percent.

Which facilities would be impacted?

In addition to the existing regulated commercial EtO sterilization facilities, the proposed update would impact the following emission sources at commercial sterilizing facilities that are currently unregulated:

  • Facilities in which EtO use is less than 1 TPY

    • Sterilization chamber vent (SCV)

    • Aeration room vent (ARV)

    • Chamber exhaust vent (CEV)

  • Facilities in which EtO use is at least 1 TPY but less than 10 TPY

    • Aeration room vent (ARV)

    • Chamber exhaust vent (CEV)

  • Facilities in which EtO use is at least 10 TPY

    • Chamber exhaust vent (CEV)

  • Room air emissions, divided into two groups—activities that occur prior to aeration (Group 1) and activities that occur after aeration (Group 2)

How would this affect air quality operating permits?

While some facilities with EtO sterilization operations are currently exempt from Title V permitting requirements under the CAA, the proposed rule would remove these exemptions and require all commercial EtO sterilization facilities to obtain a Title V permit from the delegated authority in which the source is located, regardless of the potential to emit of criteria pollutants.

What are the proposed emission standard requirements?

The EPA is generally proposing emission standard requirements for all EtO sterilizer types and room air emissions, including sources using less than 1 TPY EtO, which are currently only subject to recordkeeping requirements. Sources can comply with either emission reductions in the range of 99–99.94% or other lb/hr emission limits. Only existing Group 2 room air emission sources at area facilities using less than 20 tons per year of EtO have the option to comply with work practice standards (ISO 11135:2014 and ISO 11138-1:2017), as opposed to emission reduction or lb/hr limits. Refer to the table below for more details on proposed standards (found on page 39 of the proposal, Table 3-3. Proposed Standards, Option 2).

Proposed Standards

Group 1 and Group 2 room air emissions sources with lb/hr standards will also be required to meet Permanent Total Enclosure (PTE) requirements of EPA Method 204 of appendix M to 40 CFR part 51.

How will facilities be required to demonstrate compliance with the new rule?

The proposed rule would require facilities to demonstrate compliance through either annual performance testing with continuous parameter monitoring, or by using EtO continuous emission monitoring systems (CEMS).

The EPA’s previously approved Air Emission Measurement Center (EMC) test methods—2D, 18, and 25A, as well as California’s CARB Method 431—will be replaced with EPA Test Methods 1 and 320. The proposal also adds provisions for electronic reporting of performance test results and reports, performance evaluation reports, and compliance reports.

Finally, as part of the proposed rule, the EPA would remove exemptions for operating during periods of startup, shutdown, and malfunction (SSM) and require compliance with the standards at all times.

If the regulation is approved as proposed, facilities will be required to install pollution controls within 18 months of the final ruling. Performance test and evaluation results, notices of compliance status, and initial and ongoing compliance reports will need to be submitted within 60 days following the effective date of the final rule. The public comment period ends on June 27, 2023.

For more information on how this new ruling could affect your facility and how we can help, contact our team of air quality experts.

About the author

Samantha Anthonijs, senior environmental scientist, has 10 years of experience with air quality permitting and regulatory compliance. Her work includes assisting clients with regulatory applicability determinations, developing and negotiating air permit applications, preparing compliance plans and reports, and assessing environmental risk associated with manufacturing operations. Samantha has a special interest in the fate, transport, and redeposition of chemicals and the management of emerging pollutants. She has additional background in water quality and waste permitting and compliance, as well as manufacturing-process technology and research and development operations.


Samantha Anthonijs, Senior Environmental Scientist
Samantha Anthonijs
Senior Environmental Scientist


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