Before and After: An Evaluation of Engineering Controls for Ethylene Oxide Sterilization in Hospitals

Abstract

The control of ethylene oxide (EtO) emissions from a gas sterilizer in one hospital was evaluated before and after the installation of engineering controls. During the initial survey, full-shift personal exposures averaged 0.3 ppm and short-term exposures for the sterilizer operator averaged approximately 2 ppm for 20 minutes. The engineering modifications reduced full-shift personal exposures to less than the 0.1-ppm limit recommended by NIOSH and short-term exposures for the sterilizer operator to approximately 0.2 ppm for 20 minutes. Adding a ventilated slot hood above the sterilizer door and extending the sterilizer cycle to further reduce chamber concentrations before the door was opened reduced EtO concentrations in front of the sterilizer by more than 90 percent. Installing a ventilated enclosure around the air gap in the sterilizer discharge line and sealing its floor-drain junction reduced EtO emissions by approximately 97 percent; however, even with the required air gap enclosed and ventilated, an opening in the discharge line downstream of the vacuum pump can release a significant quantity of EtO. One potential problem which was not corrected was the control of EtO in the sterilizer recess room.