What EPA Is Doing to Address Ethylene Oxide (EtO) and to Learn More About the Chemical

As EPA pursues its mission to protect human health and the environment, addressing ethylene oxide (EtO) is a priority for the Agency. While EPA regulates EtO under a number of different environmental laws, the Agency’s current efforts to reduce this chemical’s impact fall into two main categories: regulation of air emissions of EtO under the Clean Air Act and requirements for use of EtO as a pesticide under the Federal Fungicide, Insecticide, and Rodenticide Act.  

• On April 9, 2024, EPA announced a set of final rules that will significantly reduce emissions of toxic air pollution from chemical plants, including EtO and chloroprene. The reductions will dramatically reduce the number of people with elevated air toxics-related cancer risks in communities surrounding the plants that use those two chemicals, especially communities historically overburdened by air toxics pollution.

• On March 14, 2024, EPA announced final amendments to the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Ethylene Oxide Commercial Sterilizers. This rule is one of the most important measures EPA is taking to reduce emissions of EtO and will significantly reduce lifetime cancer risks for people living near commercial sterilization facilities. 

• On January 14, 2025, EPA released the interim registration review decision for EtO pesticide risk reduction requirements under the Federal Insecticide, Fungicide, and Rodenticide Act to protect workers who use EtO to sterilize things and to protect people who work, live, or go to school near sterilization facilities.  

In addition, EPA regularly provides state agencies information on measuring EtO in air.  

EPA bases its decisions on the best available data and science. This includes collecting and sharing information about EtO use and emissions, improving the scientific ability to measure EtO in the air especially at lower levels where risk still might be occurring, and better understanding EtO risk. 

On this page:

• Final EPA Air Toxics Rules to Reduce EtO-Related Risk
• Additional EPA Actions to Reduce EtO-Related Risk
• Coordination with State Air Agencies to Reduce EtO Emissions
• Information on EtO Use and Emissions
• Current Air Monitoring Efforts
• Ongoing Research to Better Measure EtO
• Understanding EtO Risk

Final EPA Air Toxics Rules to Reduce EtO-Related Risk

1. The air toxics rule for Hazardous Organic National Emission Standards for Hazardous Air Pollutants (NESHAP), often called the "HON" 
   On April 9, 2024, EPA announced a final rule to significantly reduce emissions of toxic air pollution, including EtO and chloroprene, from plants that make synthetic organic chemicals and polymers and resins, including neoprene. 
2. Final amendments for Ethylene Oxide Commercial Sterilizers
   On March 14, 2024, EPA announced finalized requirements for nearly 90 commercial sterilizers across the country. These requirements will reduce the amount of EtO that comes out of commercial sterilizers by 90% and will significantly reduce risk in nearby communities.

3. The air toxics rule for Miscellaneous Organic Chemical Manufacturing, often called the "MON”
   In 2020, EPA finalized requirements to reduce emissions of hazardous air pollutants from the source category by 107 tons per year, which included reductions in ethylene oxide emission of approximately 0.76 tons per year. 

Additional EPA Actions to Reduce EtO-Related Risk

The  Interim Decision on EtO use as a pesticide

On January 14, 2025, EPA released the interim registration review decision for EtO, which identifies a broad set of new mitigation measures under the Federal Insecticide, Fungicide, and Rodenticide Act that, in addition to the measures included in the 2024 EtO National Emissions Standards for Hazardous Air Pollutants, will reduce exposure for workers who use EtO to sterilize medical devices and spices, and for others who work, live, or go to school near sterilization facilities.

There are additional Clean Air Act rules that govern EtO emissions. EPA is in the process of reviewing the current standards and will issue proposals at a later date.

• National Emission Standards for Hazardous Air Pollutants (NESHAP) for Polyether Polyol Production
• National Emission Standards for Hazardous Air Pollutants (NESHAP) for Chemical Manufacturing Area Sources
• National Emission Standards for Hazardous Air Pollutants (NESHAP) for Hospital Sterilizers

Coordination with State Air Agencies to Reduce EtO Emissions

The responsibility for managing air quality in the U.S. is shared by EPA and state, local and tribal air agencies. Several states are working to address EtO in their jurisdictions – often faster than what EPA’s rulemaking process can accomplish. For example, in Georgia, the state worked with two commercial sterilizers in the Atlanta area, which have installed equipment to significantly reduce EtO emissions. In Illinois, a commercial sterilizer installed state-of-the art pollution controls as required by a new state law. And in Missouri, a commercial sterilizer is voluntarily installing pollution controls. EPA has provided technical support to air agencies as part of this work. In addition, EPA is coordinating with air agencies to share information with communities about the risks from long-term exposure to EtO in the outdoor air.

Information on EtO Use and Emissions

The Air Toxics Screening Assessment (Air Tox Screen)

EPA's AirToxScreen is an ongoing review of air toxics - like EtO - in the United States. EPA developed AirToxScreen as a screening tool for state, local and tribal air agencies. AirToxScreen’s results help these agencies identify which pollutants, emission sources and places they may wish to study further to better understand any possible risks to public health from air toxics.

AirToxScreen gives a snapshot of outdoor air quality with respect to emissions of air toxics. Using this tool, you can learn about air toxics, including EtO and their emissions, in locations around the country.

EPA’s Toxics Release Inventory (TRI)

EPA's TRI provides information on the quantities of toxic chemicals that are released annually to air, water and land, or that otherwise are managed as waste by facilities throughout the United States. These facilities are mostly those involved in metal mining, electric power generation, chemical manufacturing and hazardous waste treatment, and include federal facilities. Ethylene oxide is a TRI-listed chemical, and facilities are required to report if they exceed the threshold amounts for activities such as manufacturing or processing.

In December 2021, EPA issued a decision extending TRI reporting requirements for EtO to 29 facilities. Some of the facilities must also report for ethylene glycol. Read the Federal Register notice announcing this decision. These facilities should begin tracking their chemical activities and releases and other waste management quantities in January 2022 and, if appropriate, submit TRI data beginning in 2023.

Workers in contract sterilization facilities that use EtO and communities – including historically underserved communities – living near these facilities are potentially at the highest risks of being exposed to EtO. Making more information available about releases of EtO will inform the communities that live near these facilities and will assist the agency in identifying and responding to any human health and environmental threats such releases may cause. Having to report releases to TRI makes companies more aware of their use and emission of pollutants and can lead companies to find ways to reduce those emissions.

Learn more about the TRI

Note: Not all industry sectors are covered by the TRI Program, and not all facilities in covered sectors are required to report. For a summary of TRI information on EtO, see the 2019 TRI EtO Fact Sheet. You also can use TRI Search Plus to find facilities that report ethylene oxide emissions near you.

EPA’s National Emissions Inventory (NEI)

EPA's NEI provides a detailed estimate of emissions of air pollutants, including hazardous air pollutants (EtO is a hazardous air pollutant). This inventory is released every three years, based primarily on data provided by state, local and tribal governments. Because state, local and tribal governments are not required to report hazardous air pollutants to the NEI, this inventory does not include every chemical or facility in the country.

Find EtO information from the NEI by using the “facility mapping” link at the top of the page.  Select your state, then select ethylene oxide from the pollutant list (in the pollutant list under “HAP”). Click submit to generate the map. Once you see the map, you can click on the red dots map to find the amount of EtO emissions were reported from individual facilities, or you can use the table below the map to see that information.  You also can search for total EtO emissions by industrial category using the data query link on the page.

State or local air agencies may be a source of information

Many facilities are required to have permits to emit pollution into the air. These permits limit the amount of pollutants that can be emitted. State and local agencies generally have the responsibility for permitting, and some post permits to their website. Not sure of the state agency in your area that issues such permits? Your state environmental agency is a good place to start.

Some states have their own air regulations for EtO. Your individual state environmental agency or health department may also have resources available outlining local regulations and efforts they are taking to reduce emissions and inform communities.

Current Air Monitoring Efforts

Monitoring in communities:

In recent years, several state air agencies have conducted air monitoring for EtO near known industrial sources that release EtO to the outdoor air. EPA has confidence in the results of EtO monitoring at higher concentrations -- concentrations that are well above the minimum level of EtO that the current measurement methods can detect. This includes concentrations like those measured immediately downwind of industrial sources that do not have state-of-the-art control technology in place.

EPA and other agencies also are monitoring for EtO at a number of locations in two longstanding monitoring networks that are used to track trends in toxic air pollutants (these networks are not focused on particular industrial sources). Some results of this monitoring, however, have shown much lower concentration values—closer to the method detection level—and EPA is less confident in these data. While these lower levels of EtO suggest there is a “background” level of EtO in the outdoor air, EPA is not yet certain about exact background EtO levels due to uncertainty with current measurement methods. Learn more about EPA's work in understanding background levels of Ethylene Oxide.

Read a fact sheet about EPA's Work to Understand Background Levels of Ethylene Oxide (pdf) (340.3 KB)

Monitoring worker exposure:  

In addition to monitoring efforts in communities, EPA has recently proposed new monitoring requirements for those who work in commercial sterilization facilities. To reduce risk to workers, EPA is proposing unprecedented real-time monitoring of EtO using technology with a limit of quantification at or below 10 parts per billion (ppb) of EtO in the air, the lowest possible measurement technology can currently quantify in the workplace. If levels surpass 10 ppb, workers (including office workers) would be required to wear PPE. 

Ongoing Research to Better Measure EtO

EPA is researching ways to improve our ability to measure EtO in the outdoor air. This research will help improve measurement at the source of EtO emissions (such as industrial facilities) and measurement of EtO concentrations in the outdoor air.  Understanding how much EtO is in the air and where is an important step to helping communities have a better understanding of their risk and to reducing emissions to protect health. It also will help us determine potential origins of background EtO. The objectives for this research are to: 

• Enable measurement of EtO at various levels, including at concentrations lower than what are currently possible to measure at the source of EtO emissions and in the outdoor air.
• Provide real-time testing capability to measure EtO on a continuous or near continuous basis, compared to 12- and 24-hour testing capabilities with the current method.
• Measure EtO in areas of interest to identify potential sources.  
• Improve modeling capabilities to better understand how EtO interacts with other air pollutants in the atmosphere and estimate the movement and distribution of EtO in the environment.  

Understanding EtO Risk

EPA’s Integrated Risk Information System (IRIS)

EPA’s IRIS Program supports EPA’s mission by identifying and characterizing the health hazards of chemicals found in the environment. Each IRIS assessment can cover a chemical, a group of related chemicals, or a complex mixture. IRIS assessments are an important source of toxicity information used by EPA, state and local health agencies, other federal agencies, and international health organizations.

EPA finalized the IRIS assessment of EtO in 2016. Prior to being completed, this assessment underwent two rounds of public comment and two rounds of independent, external peer review by EPA’s Science Advisory Board. The Science Advisory Board peer review process provides EPA with high-level scientific recommendations and advice from external subject matter experts about our actions and research activities. The 2016 EtO IRIS assessment informs our understanding of the human health hazards from exposure to EtO and the actions EPA is taking to reduce those risks.

Risk Assessment for People who Live Near Commercial Sterilizers

In 2022, EPA scientists and analysts completed a risk assessment for people who live near the approximately 100 commercial sterilizers currently operating in the United States.  Learn more about community engagement on EtO.

Risk Assessment for People who Apply EtO or Who Work, Live, or Attend School or Daycare Near Commercial Sterilizers

In April 2023, EPA scientists and analysts completed a risk assessment addendum for workers who use EtO to sterilize things and for others who work, live, or go to school nearby. Learn more about EtO risks and your health.