Limiting Exposure to Workplace Anesthetic Gases (WAG)

Workplace exposures to anesthetic gases occur in hospital-based and stand-alone operating rooms, PACU’s, dental offices and veterinary facilities. Sources of leaks in anesthesia equipment systems, components and accessories are identified and appropriate methods of control implemented.Inhaled anesthetic agents include two different classes of chemicals: Nitrous Oxide and Halogenated Agents.


Air monitoring is one of the fundamental tools used to evaluate workplace exposures. OSHA recommends that air sampling for anesthetic gases be conducted every 6 months to measure worker exposures and to check the effectiveness of control measures. OSHA recommends that only the agents most frequently used needs to be monitored. Three fundamental types of air samples can be taken in order to evaluate the workplace: personal, area and source samples. Personal samples give the best estimate of a worker’s exposure level. Area samples are useful for evaluating air contaminant levels in a work area.


It is vital that air monitoring be conducted when surgical cases are being performed and anesthesia agents are being used. WAG monitoring that is conducted at any other time will be inaccurate.


OSHA developed guidelines for minimizing risk to healthcare workers in their “Recommended Standard for Occupational Exposure to Waste Anesthetic Gases and Vapors” document.Currently there are no OSHA standards for waste anesthetic gases. NIOSH published “Guidelines for Healthcare Workers” and developed Recommended Exposure Limits (REL) for Nitrous Oxide of 25 parts per million as an 8-hour Time Weighted Average (TWA) when used as the sole anesthetic agent. NIOSH REL’s for halogenated anesthetic agents of 2 ppm.


Hospitals and other health care facilities that provide anesthesia services can meet key conditions of the OSHA guidelines by:


  • Minimizing employees’ exposures to Waste Anesthesia Gases to less than the NIOSH REL’s;
  • Inspect and test the operation and performance of the ventilation and HVAC system to insure an adequate number of air changes occur at a rate of 15-21 per hour;
  • Measure waste anesthesia gases in each area anesthesia is administered on a quarterly basis;
  • Make records of environmental sampling and test results available to all workers who are subject to job-related exposure to waste anesthetic gases;
  • Provide training for workers to help them recognize, understand and reduce the risks of unnecessary exposure to trace gases.