Maximum achievable control technology standards for commercial ethylene oxide (EtO) sterilizers were finalized on December 6, 1994 (59 FR 62585). The standards required controls for various sources of emissions depending on the amount of EtO used at a facility. On April 7, 2006, the EPA completed the residual risk and technology review for commercial EtO sterilizers (77 FR 17712). In December 2016, the carcinogenicity of EtO increased, causing substantial changes to risk from EtO sterilizers across the country. In this action, the EPA will propose a course of action for dealing with emissions from commercial EtO sterilizers.