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EPA Finalizes Amendments to the Miscellaneous Organic Chemical Manufacturing National Emission Standards for Hazardous Air Pollutants

Action Includes First Regulation Addressing Ethylene Oxide

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WASHINGTON (June 1, 2020) — Today, the U.S. Environmental Protection Agency (EPA) continued its progress on a suite of actions to address ethylene oxide by announcing final amendments to the Miscellaneous Organic Chemical Manufacturing National Emission Standards for Hazardous Air Pollutants (NESHAP), known as MON, to reduce hazardous air pollutants, including ethylene oxide. The final MON amendments are expected to reduce emissions of hazardous air pollutants from the source category by 107 tons per year, which includes reductions in ethylene oxide emission of approximately 0.76 tons per year. 

“EPA’s actions underscore the Trump Administration’s commitment to addressing and reducing hazardous air pollutants, including ethylene oxide emissions, across the country,” said EPA Administrator Andrew Wheeler. “Under President Trump’s leadership, we are growing our economy while protecting the environment. This rule will provide improved compliance measures for industry while continuing to clean up our air.”

This final action addresses EPA’s obligation under the Clean Air Act to conduct the residual risk and technology (RTR) review for the miscellaneous organic chemical manufacturing source category. EPA evaluated the risks posed by air toxics from this source category and determined cancer risks for this source category to be unacceptable.

To reduce risks to an acceptable level, EPA has finalized additional requirements for process vents, storage tanks, and equipment in ethylene oxide service. In addition to reducing ethylene oxide emissions, the MON amendments include updates to requirements for flares controlling ethylene oxide emissions, or emissions from processes that produce olefins and polyolefins, heat exchange systems, and equipment leaks. Once these requirements are implemented, EPA has determined that risks will be acceptable and will provide an ample margin of safety to protect public health. 

Background on Ethylene Oxide

Ethylene oxide is one of 187 hazardous air pollutants regulated by the EPA. Ethylene oxide is a flammable, colorless gas used to make other chemicals that are used in making a range of products, including antifreeze, textiles, plastics, detergents, and adhesives. Ethylene oxide also is used to sterilize equipment and plastic devices that cannot be sterilized by steam, such as medical equipment.

EPA has been taking steps to address ethylene oxide emissions after EPA’s National Air Toxics Assessment, issued in 2018, found that ethylene oxide emissions may be contributing to potentially elevated cancer risk in some areas around the country. Since then, EPA has been taking a two-pronged approach to evaluate these emissions. First, the agency is reviewing existing Clean Air Act regulations for industrial facilities that emit ethylene oxide. Second, because the process for revising our regulations takes time, EPA is gathering additional information on ethylene oxide emissions and is working with state and local air agencies to determine whether more immediate emission reduction steps may be warranted. By working with our state and local partners, we seek to identify opportunities to achieve early emission reductions.

EPA is also continuing work to address ethylene oxide from commercial sterilizers; working closely with other federal partners such as the Food and Drug Administration (FDA) to address medical device supplies; and providing an update on its work to better understand ethylene oxide – in particular, work to characterize air concentrations of this chemical. 

More information on the MON can be found at:

More information about the NATTS and UATMP data posting, can be found at:

General information about the air toxic ethylene oxide, can be found at: