A study of the technology for controlling ethylene-oxide (75218) (EtO) exposures at a hospital sterilizing facility was conducted, as part of a NIOSH survey of methods used to control EtO in hospitals. The surveyed hospital had one EtO sterilizer, two aerators, and three steam sterilizers which were located in the clean room of the central services department. The EtO sterilizer used a gas mixture consisting of a 12:88 EtO/freon mixture. Personal and area air and grab bag samples were obtained in the clean room and analyzed by gas chromatography. The area in front of the sterilizer was also monitored, and these samples were assessed by an infrared analyzer. The engineering controls were inspected. All personal time weighted average (TWA) EtO exposures were 0.05 parts per million (ppm) or less. The OSHA standard for EtO is 1ppm TWA. The monitored EtO concentrations did not exceed background values except during load transfer. The exposure of the sterilizer operator during load transfer was 0.5ppm averaged over a 15 minute period. Engineering controls included isolating all of the sterilizer except the front panel in a ventilated recess room, two vacuum purges, a 20 minute air flush and a 15 minute waiting period with the door opened a few inches during the sterilizer operation cycle, and local exhaust ventilation above the sterilizer door. EtO concentrations on the order of 20ppm were measured in the recess room during the evacuation phase of the sterilizer cycle. The authors conclude that short and long term EtO exposures are well controlled at the facility. They recommend installing an alarm system to warn workers not to enter the recess room during the evacuation phase, a supply line purge system or local exhaust ventilation above the EtO supply cylinders, and making respirators available for emergency situations.