Nahal Mogharabi, (909) 396-3773, Cell: (909) 837-2431

Kim White, (909) 396-3456, Cell: (909) 323-9479

[email protected]


South Coast AQMD Governing Board Votes to Further Protect Communities from Ethylene Oxide, reduce emissions by 99.99%

DIAMOND BAR, CA – Today, the South Coast Air Quality Management District (South Coast AQMD) Governing Board approved updates to the agency’s Rule 1405 that will strengthen requirements for sterilization and storage facilities to reduce Ethylene Oxide (EtO) emissions and further protect communities. The amended rule includes more stringent requirements than those in the recent draft rule released by the U.S. Environmental Protection Agency (U.S. EPA).

“Facilities that have voluntarily and proactively made changes in line with this rule have shown a reduction of fugitive emission by almost 100 percent,” said Vanessa Delgado, South Coast AQMD’s Governing Board Chair. “This rule is by far the most comprehensive at reducing and monitoring EtO from facilities. This is a result of a collaborative effort with stakeholders to ensure the public is protected while not negatively impacting the medical community that needs sterilized equipment.”

The updated rule applies to the 15 sterilization facilities in the south coast region. Facilities subject to the rule will be required to upgrade existing or add new pollution controls and implement measures to monitor and minimize stack and fugitive emissions. Depending on the type and size of a facility, requirements may include:

  • Enhanced monitoring system to better detect
  • Creating a permanent total enclosure that prevents fugitive toxic contaminants from escaping the building.
  • Stronger controls that prevent 99% of EtO emissions from stacks.
  • Mobile and fenceline monitoring followed by permanent continuous monitors placed in facility stacks to ensure controls are properly working.

After all requirements are in place, if ambient monitoring shows EtO levels exceed three parts per billion, the facility must curtail operations. Repeated exceedances of the threshold can result in the facility to temporarily shut down. The updated rule will allow for exemptions if critical products are in low supply based on determinations from health authorities or hospitals/medical centers.

Additionally, warehouses that receive sterilized products may also be required to monitor emissions at the fenceline to identify the level of EtO off-gassing from the materials to determine if and what controls are needed to reduce this potential.

EtO is a flammable, colorless gas used to sterilize medical equipment and make products, including antifreeze, textiles, solvents, detergents, and adhesives. Short-term exposure to EtO may cause headaches, weakness, nausea, vomiting, diarrhea, difficulty breathing, eye and skin burns, and reproductive effects. Long-term exposure to EtO over a number of years increases the risk of certain cancers including lymphoid and breast cancer.

South Coast AQMD originally adopted Rule 1405 in 1990. In March 2022, the U.S. EPA revised the cancer potency for EtO to be 30 to 50 times more toxic than previously known. South Coast AQMD conducted an extensive investigation, including evaluations and air sampling at local facilities that are permitted to use the chemical. During monitoring efforts at several commercial EtO sterilization facilities, South Coast AQMD became aware of fugitive emissions from sources that were not previously known. In addition to taking actions that have dramatically reduced facilities emissions and worker exposure to EtO, South Coast AQMD has amended Rule 1405 considering the latest findings on risk factors from the U.S. EPA and draft risk factors from the Office of Environmental Health Hazard Assessment. More information is available here:

South Coast AQMD is the regulatory agency responsible for improving air quality for large areas of Los Angeles, Orange, Riverside and San Bernardino counties, including the Coachella Valley. For news, air quality alerts, event updates and more, please visit us at, download our award-winning app, or follow us on Facebook, X (formerly known as Twitter) and Instagram.

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