Ethylene oxide is a colorless, typically odorless, flammable gas used to make other chemicals, plastic, and to sterilize certain products. Commercial sterilization includes processes that use ethylene oxide — also known as EtO — to sterilize or fumigate materials such as medical equipment and supplies, spices, and other miscellaneous items. This process is designed to eliminate microorganisms, including bacteria, viruses, and fungi, from products to ensure they are safe for human use and consumption.

The EPA, in 1994, established emission limits under the EtO Commercial Sterilization National Emission Standards for Hazardous Air Pollutants (NESHAP) to regulate EtO emitted from the nearly 90 commercial sterilization facilities in the United States.

This year, the EPA completed a residual risk and technology review under the Clean Air Act (CAA) and made no changes to the existing standards. Note, a residual risk and technology review is a two-part regulatory process under the CAA that evaluates health risks and updates emission control standards based on technological advancements.

In 2024, for the first time, the EPA conducted a second residual risk and technology review of the EtO standards and significantly tightened the regulations applicable to commercial sterilization facilities. After conducting this second review, the EPA published the 2024 final rule.

In response to legal, scientific and policy concerns, the EPA proposed in March the repeal of the 2024 final rule. Policy concerns include the EPA’s uncertainty regarding whether the statutory authority existed under the CAA to conduct the second residual risk and technology review of the EtO NESHAP, which justified the 2024 final rule. The EPA has also stated its proposed repeal is intended to ensure a strong domestic supply chain of essential sterilized medical equipment, such as wound dressings and stents.

The EPA has proposed maintaining the 2024 standards in a manner consistent with the CAA and requiring commercial sterilization facilities to install emission controls consistent with the first risk review, not the second. The EPA also estimates that the proposed action would save approximately $630 million over 20 years, or approximately $43 million annually.

The agency accepted public comments on the proposal through May 15, receiving more than 30,000 comments from environmental groups, municipalities, citizens, politicians, and corporations. it also held a virtual public hearing on April 1.

The EPA must now review and analyze the feedback received, determine whether to revise or withdraw the proposal, and publish a final rule, which is expected later this year.