Abstract: On November 12, 1991, at Merritt Peralta Hospital, while the 12:88 Castle ethylene oxide sterilizer and 3M 100% ethylene oxide sterilizer were operating, employees opened the door of the 3M sterilizer after the load was completed. Two remote sensors began sounding at both the low (20ppm) and high (50ppm) alarms. Employees evacuated. Two engineers responding to the emergency entered the area with hand-held cloths covering their noses and mouths to turn off and abort the cycle of the Castle sterilizer, close the door of the 3M sterilizer and turn it off, and reset the alarm system. The alarms continued for 27 minutes. After they stopped sounding, Employee #1, the Central Processing supervisor, re-entered and opened the sterilizer doors. Clouds of smoke came out and the alarms sounded again. Employee #1 did not have respiratory protection. He left the area until the alarms stopped five minutes later. He later reported for a medical examination, but there were no reported injuries or illnesses. Serious violations of T8CCR 5220(g)(1)(d) and T8CCR 5220(j)(3)(a) were cited.