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Waste Anesthetic Gases (WAG)

Anesthetic gases such as isoflurane are commonly used in laboratory animal research protocols.  Possible health effects of overexposure to anesthetic gas may include, but are not limited to:

   • Acute effects: Drowsiness, irritability, depression, headaches, dizziness, and nausea, as well as problems with coordination, audiovisual ability, and judgment.

   • Chronic effects: Liver and kidney disease, and adverse reproductive effects.

Always work in a well-ventilated area with at least 6 room air changes per hour (ACH) regardless of the gas scavenging methods in use. 


All staff, faculty, students, and others that work or spend time in; operating rooms, recovery rooms, radiology, and storerooms where anesthetic gases are used, stored, or transported are covered under this procedure.  Environment, Health, and Safety can assist campus groups by providing a variety of health and safety services.


University Administration

University Administrators provide senior management support for implementing the EHS Waste Anesthetic Gas (WAG) Guidance and ensures that resources are allocated for implementing these procedures.

Environment, Health, and Safety

The Department of Environment, Health, and Safety develops and oversees the implementation of the EHS Waste Anesthetic Gas (WAG) Guidance by:

  • Providing oversight, leadership, and technical expertise to develop a safety program that provides awareness training, technical advice for compliance, exposure monitoring, and emergency response.  Emergency response can include responding to worker exposures, addressing leaks and spills, providing response to spills and/or clean up, and incident investigations.
  • Communicating the procedure to all areas of campus that this standard covers.
  • Utilizing industry accepted sampling protocols.
  • Maintaining all sampling equipment and instrumentation that is used in WAG sampling and emergency response.
  • Maintain all records for training, exposure monitoring, reports, and recommendations.

Research or Clinical Personnel

All Cornell research or clinical personnel that fall under this procedure are responsible for:

  • Receiving training on proper use of anesthetic gas systems and hazard communication training on anesthetic gases.
  • Using anesthetic gases in a manner consistent with the design of the machine and the scavenging system used.  The employee shall ask their supervisor for assistance in the event of problems or difficulties.
  • Operating and checking all equipment prior to use and reporting problems to your supervisor immediately.
  • Following all manufactures recommendations regarding gas delivery and scavenging systems.                                                   

Principal Investigators (PIs) and Supervisors

Cornell University PIs and Supervisors support the Anesthetic Gas Safety Program by:

     • Providing work conditions in compliance with this procedure for those being supervised, and for following up on reports of violations of safe working conditions.

     • Ensuring that all employees receive appropriate training for the use of anesthetic gas and scavenging systems. 

Additionally, the supervisor is responsible that all employees and students are familiar with this written program and all components of this program as followed.

Engineering Controls

Work in a certified chemical fume hood or ducted biosafety cabinet (BSC) for best WAG capture:

Active Circuit

Method 1a – A vacuum pump device in the breathing system.  Devices (e.g., EVAC-4, SOMNI EPS-3, VetEquip cube) are ducted to the building exhaust system.

Method 1b – A vacuum pump device in the breathing system.  Devices are connected to an activated charcoal canister.

Passive Circuit with Active Scavenging

Method 2 – Localized exhaust ventilation (e.g., Snorkel, Fume Hood, Downdraft Table) is positioned near the breathing system to draw and/or capture WAG.   An activated charcoal canister is used for gas deactivation.

Safe Work Practices

Preparing for anesthetic gas use:

     • Complete EHS 2815 - Waste Anesthetic Gases Safety (WAGs) in CULearn.

     • Inspect anesthesia equipment and the scavenging system. 

     • Verify equipment (e.g., fume hood and vaporizer) is currently certified and in proper working condition.  Preform a pressure test to check for leaks, defects, and damage in anesthesia equipment (including hoses and valves) and the scavenging system.

     • Verify Fill vaporizer using an anti-spill bottle adaptor.  

Preparing charcoal canisters for use:

     • Charcoal canisters must be weighed before and after each use to ensure they are within the manufacturer’s specified limits (e.g., <50 grams above the initial weight or 12 hours of use); record the weight on the canister.

     • Confirm that the canister is correctly plugged into the breathing system.  Use charcoal canisters according to manufacturer’s recommendations.

     • Ensure the canister holes are not obstructed, canisters must be used upright.

For anesthetic inductions:

     • Open-drop anesthetic procedures are not recommended and must be conducted within a chemical fume hood.

     • Do not turn on the vaporizer until the animal is in the induction chamber.

     • Before retrieving the anesthetized animal, purge the induction chamber with oxygen for 5 to 15 seconds prior to opening the chamber.

     • Keep the vaporizer turned off or the nosecone plugged until the animal is properly positioned in the nose cone.

     • Turn off the vaporizer or plug the nosecone before taking the animal out of the nose cone.

     • Frequently inspect the condition of the induction chamber seal and the scavenging system for leaks.

For surgical procedures:

Minimize WAG leakage from the nose cone by selecting the best fitting nose cone. To optimize the fit, nose cone diaphragms are often available from the manufacturer.  

    • Oxygen flow rate and anesthetic concentration should be as low as possible to minimize anesthetic gas usage.

    • Keep WAG scavenging devices positioned as close as possible to potential points of release (e.g., at animal nosecone).

    • Keep the individual’s breathing zone away from the animal nosecone.

For imaging procedures:

    • Close or plug the nose ports inside the imaging machine if they are not in use.


Measure human exposure to WAG whenever:  

   • There is a new setup, or an existing setup has not been used within one year.

   • Anesthetic gas can be smelled.

   • People are experiencing fatigue or headaches when using the anesthetic equipment.

Human exposure monitoring is conducted by EHS.  Contact EHS (607-255-8200, askEHS) for scheduling of WAG monitoring or set-up review.

Personal Protective Equipment

   • Standard PPE for isoflurane users is safety glasses, nitrile gloves, and lab coats.

   • Additional PPE may be needed if additional hazards are present during use.


Whenever transporting chemicals by hand, always use a secondary container such as a rubber acid carrying bucket, plastic bucket, or a 5-gallon pail. 

If necessary, a small amount of packing material (shipping peanuts, vermiculite, or cardboard inserts), that is compatible with the chemical(s), should be used to prevent bottles from tipping over or breaking during transport. 

Proper PPE must be accessible in case a spill occurs.

Emergency Preparedness

First Aid

   • For medical emergencies, call 911 from a campus phone or (607) 255-1111 from a cell phone.

   • Know where the nearest emergency eyewash and safety shower are located.

For spills outside of a fume hood or hard-ducted biosafety cabinet:

   • Leave the room and call (607) 255-1111 for assistance with spill clean-up.

For spills inside a fume hood:

   • Notify other people in the area that a spill has occurred.  Prevent others from entering the spill zone.  The first priority is always to protect yourself and others.

   • Stop the source of the spill if possible, and if safe to do so.  

   • Try to prevent spilled chemicals from entering waterways by building a dike around access points (sink, cup sinks) with absorbent material if you can safely do so.

   • Slowly add absorbent material on and around the spill and allow the chemical to absorb.  Apply enough absorbent to completely cover the spilled liquid.  Sweep up the absorbed spill from the outside towards the middle.  Scoop up and deposit in a leak-proof container.

   • Label the container and dispose of through the hazardous waste management program.

   • Wash the contaminated surface with soapy water.

   • Report the spill to your supervisor.  Restock any supplies that you may have used from any spill kits.

Waste Management

   • Manage unused/expired anesthetic gases and liquids as hazardous waste.

   • Empty isoflurane bottles can be disposed of as non-hazardous waste.  Deface labels and discard in the regular trash.

   • Manage used charcoal canisters as hazardous waste.

Equipment Maintenance

   • Anesthesia machines and vaporizers are to be calibrated and certified as recommended by the manufacturer.  Contact CARE ( to schedule annual inspection / certification of anesthetic equipment.

   • Frequently inspect the condition of the induction chamber seal and the scavenging system for leaks.

Standard Operating Procedures (SOPs)

   • Establish lab-specific Standard Operating Procedures (SOPs) for routine use, inspection, and maintenance of anesthesia and scavenging systems.

   • Train new users using the SOP and document the on-site training.

For questions on Waste Anesthetic Gas Safety or personal monitoring, please contact