Hygiene aspects of occupational exposure to waste anaesthetic gases in Ontario hospitals.
Exposure of workers to waste anaesthetic gases in the operating and recovery rooms of hospitals is an ongoing concern because a number of epidemiological and mortality studies have reported significant adverse effects. To evaluate the health risks if any, and to assist in the development of guidelines or regulations for the hospital sector in Ontario, the Health and Safety Support Services Branch of the Ontario Ministry of Labour conducted this extensive study. The results of the hygiene study show that exposure to waste anaesthetic occurs because of leaks in the anesthetic equipment. The three major sources of leaks (i.e. exhalation valves, masks and high-pressure fittings) produced concentrations above the limit of detection of nitrous oxide (1000 ppm of N2O) in a significant number of samples. Of the samples taken at leak sources those taken at the exhalation valve had the highest percentage of samples above 1000 ppm, which suggested that scavenging systems were not receiving proper service and maintenance. Only 23% of the operating rooms surveyed met the Ontario Ministry of Health Criterion of 24 air changes per hour. Dilution ventilation was less effective than scavenging in keeping down concentrations of air contaminants. The sampling data show that the anaesthetists have the highest time-weighted average exposure (median value range 56-79 ppm) of the major group of occupations surveyed and that the general surgeons' TWA is much lower (28 ppm). It was concluded that the dilution ventilation rate of 24 air changes per hour should be maintained in all operating rooms and that there should be no recirculation of exhaust air when operations are in progress. To keep down concentrations of anaesthetic gases scavenging systems should be provided in all operating rooms. In each hospital maintenance should be the responsibility of a qualified staff member who has been adequately trained in the repair and maintenance of anaesthetic delivery systems. Finally, a qualified staff member should be responsible for conducting periodic personal monitoring in operating rooms (ORs) and recovery rooms (RRs) and the sampling strategy should include individuals and the exhaust grilles.
Rajhans
G S
GS
Brown
D A
DA
Whaley
D
D
Wong
L
L
Guirguis
S S
SS
D000395:Air Pollutants, Occupational / Q000032:analysis*; D000397:Air Pollution / Q000517:prevention & control; D000776:Anesthesiology / Q000295:instrumentation; D000777:Anesthetics / Q000032:analysis*; D006256:Hazardous Waste / Q000032:analysis*; D009864:Ontario
D000395:Air Pollutants, Occupational; D000777:Anesthetics; D006256:Hazardous Waste