Anaesthetic gases are used to block the sensation of pain during medical procedures and include nitrous oxide and halogenated anaesthetics, such as desflurane, enflurane, halothane, isoflurane, and sevoflurane.
Waste Anaesthetic Gases (WAG) are anaesthetic vapours that leak into the surrounding environment and can result in worker exposure in hospitals, dental offices, animal facilities and research laboratories. The sources of waste anaesthetic gases in healthcare settings are leaks from anaesthetic equipment, improper installation of scavenging systems, leaks from patients’ masks, and exhalation of gases by patients.
Anesthetic gases cannot be detected by odour until their concentrations are much higher than occupational exposure limits. Air testing for anesthetic gases allows determination of direct worker exposure and routine monitoring to identify problems in anaesthetic gas systems.
Short-term exposure to waste anaesthetic gases can cause fatigue, drowsiness, and headache. Long-term exposure to low levels of anaesthetic gases can contribute to a greater risk of infertility, genetic abnormalities, miscarriages, and cancer.
The Department of Labour in the United States set the exposure limits for nitrous oxide at 25 ppm and halogenated agents at 2 ppm, based on recommendations from NIOSH.
In Ontario, the limit for time-weighted average exposure value (TWAEV) is 25 ppm for nitrous oxide and 2 ppm for isoflurane and enflurane, according to regulation 833 – the Control of Exposure to Biological or Chemical Agents section of the Ontario Occupational Health and Safety Act (OHSA).
The Canadian Centre for Occupational Health and Safety (CCOHS) recommends that an anaesthetic gas management program should include engineering controls, safe work practices, air monitoring, hazard communication and training.
Samples are collected using a sorbent tube near the breathing zone of workers to determine TWA exposure.
Nitrous Oxide: CTL Method (TD-GC-ECD)
Halogenated Anaesthetic Gases: Modified OSHA 103, OSHA 106 (GC-FID)