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Illinois EPA information on Ethylene Oxide

Ethylene Oxide (C2H4O)

Ethylene oxide is a flammable, colorless gas.  It is produced and used to make a range of products, including antifreeze, textiles, plastics, detergents and adhesives. Ethylene oxide also is used to sterilize some medical equipment that cannot otherwise be sterilized by steam, ultraviolet light or other means, such as certain plastic and electronic devices.  Ethylene oxide is also emitted in extremely small amounts from combustion of fuels.

The Clean Air Act lists ethylene oxide as a hazardous air pollutant (HAP). The Clean Air Act requires the USEPA to regulate hazardous air pollutants from categories of industrial facilities. In December 2016, U.S. EPA updated its Integrated Risk Information System (IRIS) value for ethylene oxide.


Sterilization of medical devices is an essential aspect of modern medicine. There are several technologies to sterilize medical products and devices; however, many medical devices are sterilized using ethylene oxide because they have plastic parts or instrumentation that can be damaged by alternatives such as steam, high heat or radiation.  The Food and Drug Administration (FDA) regulates the sterilization of medical devices such that medical providers have a supply of sterilized medical devices.  While the FDA has stated that it will be studying alternatives to ethylene oxide sterilization, it has not identified potential alternatives for near term approval. 

Statutory and Regulatory Background

Since passage of the federal Clean Air Act (CAA) in 1970, there have been enormous reductions in emissions and corresponding improvements to ambient air quality.  The original CAA focused on common air pollutants, some of which, such as ozone and particulate matter, were at times causing acute health problems in certain parts of the country. 

With passage of the 1990 Amendments to the CAA, USEPA began to set emission standards for HAP.  Since that time, total emissions of hazardous air pollutants have declined. These National Emission Standards for Hazardous Air Pollutants (NESHAP) are technology-based standards to reduce HAP emissions from specific industries.  The NESHAP for commercial sterilization plants was adopted in 1994, requiring control equipment to be added to commercial sterilizers reducing ethylene oxide emissions.  NESHAPs are meant to be revisited by USEPA on a periodic basis to incorporate new science on hazardous air pollutants.

USEPA revisited the public health science and published a new IRIS value for ethylene oxide in December 2016. IRIS data is used by USEPA in evaluating risk of HAPs.  With the new IRIS value for ethylene oxide, the USEPA began to review sources of ethylene oxide emissions including commercial sterilization facilities and performed dispersion modeling of the facilities nationwide.  In reviewing the modeling and comparing to the IRIS value, certain facilities showed a higher than acceptable risk value at which further control of emissions is appropriate.  USEPA typically regards a chronic risk (lifetime) of more than 1 in 10,000 to be higher than acceptable. 

The USEPA released this information to states and the public in August 2018 with the release of the most recent National Air Toxics Assessment.  USEPA is moving forward with revising the NESHAP for commercial sterilization facilities in light of this information.

Permitting and Regulation of Stationary Sources

Among other things, the Illinois EPA enforces federal and state air pollution control laws and rules including NESHAP standards. One way Illinois EPA does so is with permitting of emitting facilities. The Illinois EPA takes seriously its statutory mandate to protect ambient air quality.

Since the release by USEPA of the National Air Toxics Assessment and subsequent ambient monitoring data for Willowbrook, the Illinois EPA evaluated sources of ethylene oxide emissions including those in Lake County.  The Agency has devoted a great deal of time and resources to understanding the issues around ethylene oxide including the location, emissions, air quality contribution, and existing and potential additional control measures for sources of ethylene oxide.    

Although revised federal standards (NESHAPs) for ethylene oxide have not yet been proposed by the USEPA, the USEPA is working to that end.

Separately, the Illinois EPA is requiring facilities to take actions to reduce their ethylene oxide emissions to be protective of ambient air quality.   

​On May 30, 2019, the Illinois General Assembly passed Senate Bills 1854 and 1852 addressing sources of ethylene oxide emissions.  Governor Pritzker signed these two bills into law, as Public Act 101-0022 and Public Act 101-0023 respectively, on June 21, 2019 with an immediate effective date. These two pieces of bipartisan legislation impose the strictest limits in the nation on ethylene oxide emissions from ethylene oxide sterilization facilities and other companies that use ethylene oxide.

Under Senate Bill 1852, ethylene oxide (EtO) sterilization facilities are prohibited from operating in Illinois unless:

  1. The facility captures 100 percent of all fugitive ethylene oxide emissions within the facility.

  2. The facility reduces ethylene oxide emissions to the atmosphere from each exhaust point by at least 99.9 percent or to 0.2 parts per million.

The bill requires facilities to conduct an initial emissions test within 180 days and yearly tests thereafter, and the results must be submitted to the Illinois EPA. Upon receiving a failed emissions test, a facility must:

  • Immediately cease operations.

  • Notify the Illinois EPA within 24 hours.

  • Within 60 days, conduct a root cause analysis of the failed emission test, take corresponding corrective actions, and seek IEPA approval prior to restart of operations.

The measure also requires EtO sterilization facilities to conduct quarterly ambient air testing and to obtain construction permits from the Illinois Environmental Protection Agency before making the modifications required to comply with the emissions limits in the legislation. After January 1, 2020, any new facility seeking a permit to sterilize with EtO must comply with setback requirements mandating that the facility be located at least 10 miles from schools or parks. 

Senate Bill 1854 applies emission limits on non-sterilization facilities that emit ethylene oxide. Beginniing 180 days from passage, any such EtO facility was required to obtain a permit from IEPA, which included a site-specific cap on the facility's EtO emissions.

Medline Industries

Medline Industries is a commercial sterilizer located at 1160 Northpoint Boulevard in Waukegan.  Medline uses ethylene oxide to sterilize medical equipment and devices. The facility operates under a federally enforceable state operating (FESOP) permit. 

To address its ethylene oxide emissions, Medline applied for and the Illinois EPA issued a construction permit to the facility.  The construction permit may be found in the Documents and Links section below.  Under the construction permit, Medline installed several new emission controls, placed the building under 100% capture (negative air pressure) and routed all emissions through control devices.  The construction permit includes performance requirements for the control devices and a limit on emissions from the facility of 150 pounds per year. Additionally, the permit requires a state of the art emissions monitor to be installed and a stack test to be performed to verify compliance.  The measures set forth in the permit go well beyond measures required under the current NESHAP Subpart O and significantly reduce the emissions and impact from Medline. Dispersion modeling for Medline with these changes was performed which showed that with these changes, Medline's impact is far below USEPA’s reference 1 in 10,000 risk level. 

The Illinois EPA held a public meeting in Waukegan to answer questions related to the permit on May 23, 2019 at Whittier Elementary School in Waukegan. 

On May 30, 2019, the Illinois EPA issued construction permit 19020013 to Medline to install the controls and monitoring described above.

Vantage Industries

Vantage Specialties, Inc. (Vantage), located at 3938 Porett Dr. in Gurnee, manufactures ingredients used in personal care, food and industrial products. The reactors in the alkoxylation area of the plant use ethylene oxide as a raw material. The ethylene oxide is piped into sealed reactors along with other raw materials. The ethylene oxide reacts with the other raw materials to form the desired chemical products. This consumes the ethylene oxide with only a small amount of unreacted ethylene oxide left, which is then vented to a scrubber followed by a dry bed absorption device. This dry bed device was installed in April 2019 to further reduce emissions.

Vantage applied for a construction permit that would set an annual cap on emissions of ethylene oxide from the plant as required by Public Act 101-0023, which took effect June 21, 2019. The Illinois EPA Bureau of Air drafted a permit that set an annual cap on emissions of ethylene oxide from the plant of 110 pounds per year of which no more than 60 pounds may be fugitive emissions from components. The permit also included conditions that would address how compliance with the cap on emissions is to be determined, including requirements for monitoring, recordkeeping and reporting.

The Illinois EPA held a formal public meeting to accept oral comments on a draft construction permit for Vantage Specialties, Inc. on November 14th, 2019 at the College of Lake County Auditorium. The issued permit may be found in the documents section below.


Sterigenics is a commercial sterilizer that was operating out of two buildings, Willowbrook I and Willowbrook II, located at 7775 Quincy Street and 830 Midway in Willowbrook. The facility has not operated since a February 15, 2019 seal order was put in place. The company permanently ceased operations at the site in September 2019. 

Documents and Links


Illinois EPA Modelling Review Memorandum - If you would like a copy of the modelling files please send an e-mail requesting the files to the contact listed above. 



The above three documents have been submitted to the Illinois EPA by Sterigenics pursuant to the Consent Order.  Sterigenics notes in the Transmittal Letter that it intends to close the Willowbrook facility permanently.