Inhalation anaesthetics--exposure and control during veterinary surgery.

Results are reported for air sampling surveys carried out by the Health and Safety Executive (HSE) in 14 veterinary surgeries. For all personnel the geometric mean (GM) time-weighted average (TWA) exposures to halothane and nitrous oxide over the working period were 2.6 ppm (range: less than 0.5 119 ppm) and 100 ppm (range: 14-1700 ppm), respectively. Since surgery rarely lasted for more than 4 h the corresponding GMs for 8-h TWAs were lower, being 1.3 ppm (range: less than 0.5-34 ppm) for halothane and 34 ppm (range: 5-530 ppm) for nitrous oxide. The GM exposures of veterinarians and nurses were very similar. The size of the practice and the use of scavenging were significant factors in determining personal exposures to inhalation anaesthetics: by comparison general ventilation had little effect. The results are compared with earlier data from human surgery, and previous studies of exposure to inhalation anaesthetics during veterinary surgery are briefly reviewed.