Concentration of halothane in veterinary operating and treatment rooms

Fourteen operating rooms and 3 treatment rooms in veterinary facilities were monitored for ambient halothane. All rooms except 1 were in private practices, Regularly scheduled surgical or dental procedures were monitored under routine working situations of each facility. The mean maximal steady halothane value for all rooms was 4.7 ppm, with a range of 1.1. to 18 ppm. In 10 of the 17 rooms, concentrations exceeded the recommended maximum of 2 ppm. Rooms that had scavenging devices averaged 1.4 ppm whereas rooms without scavenging devices averaged 5.2 ppm. The average room volume for the 17 rooms was 39.7 m3, with a range of 21.6 to 79 m3. The average ventilation or air movement for 11 rooms was 6 rooms air exchanges/hour. The average time spent in the rooms during halothane usage was 1.8 hours.