At their December 1st meeting, the South Coast AQMD Governing Board approved amendments 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 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 EtO emissions. Depending on the type and size of a facility, requirements may include:

• Creating a permanent total enclosure that prevents fugitive toxic contaminants from escaping the building.

• Stronger controls that prevent 99.99% of EtO emissions from stacks.

• Mobile and fenceline monitoring followed by permanent continuous monitors placed in facility stacks to ensure controls are properly working.

• Enhanced monitoring system to better detect leaks.

After all requirements are in place, if ambient monitoring shows EtO levels exceed three parts per billion (ppb), 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, if any, of EtO off-gassing from the materials. This information will be used to determine if any additional controls or measures are necessary.

EtO is a flammable, colorless gas used to sterilize medical equipment and make products, including antifreeze, textiles, solvents, detergents, and adhesives. Long-term exposure to EtO 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 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. More information is available here.