Waste anesthetic gases are a concern for veterinarians as they pose potential health risks for the hospital staff. Below are some frequently asked questions that may address some of your concerns.

What are Waste Anesthetic Gases?

Waste anesthetic gases are any inhalant anesthetics that leak into a room during the administration of general anesthesia. Potential sources of waste anesthetic gas include the anesthesia machine and associated equipment during the procedure and then the patient as they continue to expire anesthetic gas during the initial recovery period. Any personnel in the room during the procedure or recovery would potentially be exposed to waste anesthetic gases.

Can Waste Anesthetic Gases Cause Any Potential Harm?

The exact nature and severity of any health risks associated with exposure to inhalant anesthetic is a controversial and debated topic. The potential health effects of exposure to waste anesthetic gases includes headaches, nausea, fatigue, reproductive problems, and cancer (OSHA).

Are There Recommendations Regarding Exposure to Waste Anesthetic Gases?

The National Institute of Occupational Safety and Health (NIOSH) has published general recommended exposure limits for halogenated anesthetic agents. NIOSH recommends that personnel should not be exposed to any halogenated agent at ceiling concentrations greater than 2 ppm over a sampling period not to exceed one hour (NIOSH 1977).

How Do We Determine Our Actual Exposure to Waste Anesthetic Gases?

Exposure to waste anesthetic gases can be measured by wearing an exposure badge during a clinic day. At the end of the day the badge is sent out and the amount of isoflurane or sevoflurane is measured and the information is reported back. It is recommended that personnel exposure be measured every 6 months (OSHA).

How Can My Anesthetic Practice Help Minimize Exposure to Waste Anesthetic Gases?

How we provide anesthesia can have a significant impact on the level of our exposure to anesthetic waste gases. Anesthesia equipment should be leak tested before each use and any leaks should be corrected immediately.

Common causes of leaks include cracked breathing hoses, small cracks in the rebreathing bag, or a misaligned CO2 adsorbent canister. Every anesthesia machine should be connected to an appropriately functioning scavenging system.

Mask or chamber inductions should be avoided since they result in massive amounts of room contamination and personnel exposure. During anesthetic induction, the vaporizer should not be turned on until the endotracheal tube has been leak tested and a seal confirmed. Once the vaporizer has been turned on any unnecessary disconnections should be avoided since they will result in exposure.

If a patient needs to be disconnected in order to move to another area of the hospital, then the vaporizer and flowmeter should be turned off and the rebreathing bag emptied prior to disconnection. If the patient is being disconnected temporarily for a change of position, then the Y piece should be occluded during the disconnection. When the procedure is complete patients should remain intubated and attached to the anesthesia machine as long as possible so that the maximal amount of waste gas can be collected into the scavenging system. Care should be used when filling anesthesia vaporizers and any spills should be cleaned up immediately with appropriate disposal of any contaminated material.


National Institute for Occupational Safety and Health. (1977) Criteria for a recommended standard: Occupational Exposure to Waste Anesthetic Gases and Vapors. Cincinnati, OH: U.S. Department of Health, Education, and Welfare. Public Health Service. Center for Disease Control. National Institute for Occupational Safety and Health. DHEW (NIOSH) Publication No. 77-140.

Occupational Safety and Health Administration (OSHA). (2000) Anesthetic Gases: Guidelines for Workplace Exposures. www.osha.gov/dts/osta/anestheticgases.