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Ethylene Oxide

Ethylene oxide (EtO) is a flammable, colorless gas used to make other chemicals necessary in the production of 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.

Ethylene oxide in the air can come from different types of sources, including industries such as chemical manufacturers and sterilizers.

Evonik Corporation

Evonik Corporation, located at 337 Vincent Street in Milton, WI, is a chemical manufacturing plant. Previously, the facility was also known as Air Products Performance and Tomah Products. This location has held an active air permit since 1990. The DNR inspected Evonik in May 2018 and found no evidence of noncompliance.

Evonik company sign

Evonik manufactures specialty chemicals, primarily sold as components to formulators and commonly known as surfactants. Surfactants are compounds that lower the surface tension between two liquids, a liquid and a gas or a liquid and a solid. The resulting products are used as components in household, industrial and institutional cleaners as well as mining, roof coatings, asphalt and other industrial applications. This facility is regulated under Wisconsin's state air toxics rule (NR445) [exit DNR], and the state has worked with the this location since 2010 to reduce emissions and obtain the best annual emission estimates for ethylene oxide (EtO).

Obtaining the best annual emission estimates is challenging. Most calculated emissions are not from stacks or vents but are released from over 2000 fugitive components such as valves, flanges, connectors, pumps and seals. The intermittent nature of these fugitive emissions is difficult to quantify.

Estimates of ethylene oxide emissions from Evonik Materials Corporation have dropped by more than 5-fold over the last 10 years due to a systematic verification of emissions calculations.

Year EtO Reported Emissions (Lbs/year)
2019 111.45
2018 167.3
2017* 348.6
2016 239.6
2015 638.4
2014* 792.4
2013 580.6
2012 1,641.0

* indicates years included in recent and future National Air Toxics Assessment (NATA) risk analysis

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