Waste Anesthetic Gases (WAG)

Waste anesthetic gases (WAGs) are anesthetic gases and vapors that enter the work area during filling, induction, anesthesia, recovery, equipment disconnection, or a leak. Common agents include isoflurane, sevoflurane, desflurane, and nitrous oxide. Cornell’s WAG Program applies engineering controls, safe work practices, equipment maintenance, training, and exposure monitoring to keep exposures as low as reasonably achievable.

Questions and early requests for assistance are encouraged. Contact EHS when planning or changing a setup, purchasing equipment, interpreting monitoring results, or addressing a concern. Raising a concern does not imply that anyone has done something wrong; early reporting helps Cornell correct problems before an exposure or incident occurs.

What You Need to Do

Before beginning work: Complete EHS 2815 – Waste Anesthetic Gases Safety (WAGs) and documented, site-specific training on the anesthetic-delivery and scavenging systems you will use.
Before placing a new or changed setup into routine use: Contact askEHS for setup review and baseline exposure monitoring.
Before each use: Inspect the delivery and scavenging systems, perform the manufacturer-recommended leak or pressure test, and confirm that ventilation and scavenging are operating.
During use: Follow the laboratory- or unit-specific SOP and use the equipment only as trained.
At least once every two years: Ensure EHS has evaluated each setup during a representative procedure. Contact EHS if you are unsure whether monitoring is current.
Whenever something seems wrong: Stop work when safe to do so and report odors, symptoms, leaks, equipment or scavenging failures, spills, or other concerns promptly.

Get Help Quickly

For routine questions, setup reviews, or exposure monitoring, submit an askEHS request. To help EHS respond efficiently, include:

Your name, PI or unit, building, room, and contact information.
The anesthetic agent and the animal or procedure involved.
The delivery equipment, scavenging method, and local exhaust or room ventilation used.
Whether the setup is new, relocated, modified, overdue for monitoring, or associated with an odor, symptom, spill, leak, or other concern.
Photographs, equipment information, and anticipated dates of use, when available.

If anyone has severe symptoms, loses consciousness, or needs immediate medical assistance, call 911. For an uncontrolled release or other immediate danger, leave the area, prevent entry, and follow the emergency procedures for your Cornell location.

Scope

This program applies to Cornell research, teaching, clinical, imaging, animal-care, and support locations where anesthetic gases are used or where people may be occupationally exposed. It covers faculty, staff, students, volunteers, visitors, and other personnel who use anesthetic gases or routinely work in affected areas.

For this program, a setup is a specific combination of location, anesthetic-delivery equipment, scavenging method, ventilation or local exhaust, and procedure or work practice. Moving equipment or materially changing any of these elements may create a new or changed setup that requires EHS review.

Health Information

Effective scavenging and good work practices can prevent or substantially reduce exposure. Possible symptoms of overexposure include headache, fatigue, drowsiness, dizziness, nausea, irritability, and difficulty with coordination or judgment. Repeated or poorly controlled exposure may present additional health risks, including reproductive concerns.

Odor is not a reliable measure of exposure. Do not wait for an odor or symptoms before reporting a suspected leak or control problem.

Anyone with exposure concerns, including concerns related to pregnancy or reproductive health, may request a confidential consultation through Cornell’s Reproductive Health Program or the occupational-health service available at their Cornell location.

Responsibilities

Environment, Health and Safety

EHS is responsible for:

Maintaining the university WAG Program and providing technical consultation, training, setup review, exposure monitoring, incident support, and recommendations.
Maintaining an inventory and monitoring schedule for identified setups.
Conducting baseline, biennial, and event-triggered exposure monitoring using appropriate personal, task-based, area, or direct-reading methods.
Explaining monitoring results in plain language, including what was measured, the evaluation criteria used, any required corrective actions, and whether follow-up monitoring is needed.
Maintaining exposure-monitoring records and communicating recommendations to the responsible unit.
Helping units select, design, and improve anesthetic-gas controls.

Principal Investigators and Supervisors

PIs and supervisors are responsible for:

Identifying personnel and locations covered by this program.
Ensuring required EHS and site-specific training is completed before work begins.
Maintaining a setup-specific SOP covering routine use, pre-use inspections, leak checks, scavenging, charcoal-canister management when applicable, recovery, maintenance, spills, and emergency actions.
Contacting EHS before routine use of a new, relocated, or materially changed setup and cooperating with biennial and event-triggered monitoring.
Ensuring equipment is inspected, maintained, and serviced according to the manufacturer’s instructions and the unit’s preventive-maintenance program.
Responding promptly to concerns and implementing corrective actions identified by EHS.
Supporting personnel who pause work or report a possible exposure, leak, equipment problem, or unsafe condition.

Personnel

Personnel covered by this program are responsible for:

Completing EHS 2815 and documented, site-specific training before beginning work.
Following the applicable SOP, equipment instructions, and required controls.
Inspecting the delivery and scavenging systems before each use and completing the required leak or pressure test.
Stopping work when safe to do so and promptly reporting odors, symptoms, spills, leaks, damaged equipment, scavenging problems, or other concerns.
Participating in exposure monitoring when requested.

Engineering Controls

Capture WAGs as close as practicable to the point of release. A scavenging system is required wherever inhalation anesthetics are administered unless EHS has reviewed and approved an alternative control strategy.

Preferred controls, selected to fit the equipment and procedure, include:

A properly designed active scavenging system that discharges through approved building exhaust.
Approved local exhaust positioned to capture gas at an induction chamber, nose cone, mask, imaging port, or recovery location.
A passive system using an agent-compatible activated-charcoal canister when active exhaust is not practicable and EHS has confirmed that the setup controls exposure.
A certified chemical fume hood for compatible procedures.

General room ventilation supports exposure control but does not replace source capture or scavenging. Do not use a biosafety cabinet to control anesthetic vapors unless EHS has confirmed that the cabinet type, exhaust connection, and proposed procedure are appropriate for volatile chemicals. Do not modify or connect scavenging equipment to building systems without authorization from the responsible facilities unit and EHS review.

Safe Work Practices

Before Use

Confirm that the equipment, vaporizer, ventilation, and scavenging system are in service and appropriate for the procedure.
Inspect hoses, seals, valves, connectors, breathing circuits, induction chambers, masks, nose cones, and scavenging components for wear, damage, disconnection, or obstruction.
Perform the manufacturer-recommended leak or pressure test before each use. Remove equipment from service if it does not pass.
Fill vaporizers in a chemical fume hood or other EHS-approved ventilated location using a keyed filler, anti-spill adaptor, or other closed-transfer device compatible with the agent and vaporizer.

During Induction and Anesthesia

Place the animal in the induction chamber or fit the mask or nose cone before turning on the anesthetic.
Use the lowest fresh-gas flow and anesthetic concentration compatible with animal welfare, the procedure, and the equipment manufacturer’s instructions.
Use a properly fitted mask, nose cone, or cuffed endotracheal tube, as appropriate, to minimize leakage.
Keep local exhaust in the effective capture position and keep personnel breathing zones out of the path between the emission source and exhaust.
Turn off the vaporizer before disconnecting the animal or opening the induction chamber.
Purge the chamber and breathing circuit through the scavenging system for the time specified in the setup-specific SOP before opening or disconnecting the system.
Do not perform open-drop anesthesia outside a certified chemical fume hood or another EHS-approved control.

Recovery and Imaging

Manage animal recovery in a location with ventilation or source capture appropriate to the procedure and species.
Close or plug unused anesthetic ports in imaging and multi-station systems.
Keep scavenging connected and operating until anesthetic delivery has stopped and residual gas has been cleared as specified in the SOP.

Activated-Charcoal Canisters

Use only canisters that the manufacturer identifies as compatible with the anesthetic agent.
Keep the canister upright, with all inlet and outlet openings unobstructed.
Record the initial weight and track use as directed by the manufacturer.
Replace the canister when it reaches the manufacturer’s weight-gain, service-time, or other replacement limit. Do not rely on odor to determine saturation.

Exposure Monitoring

EHS conducts exposure monitoring during representative use of each setup. Monitoring may include personal breathing-zone sampling, task-based sampling, direct-reading measurements, area measurements, leak detection, or airflow evaluation. General room-air sampling alone may not represent the exposure of the person closest to the animal or equipment.

Monitoring is required:

Before a new setup is placed into routine use.
At least once every two years for each setup.
When a setup is relocated or materially changed, including changes to equipment, scavenging, ventilation, procedures, animal species or size, or work practices that could affect exposure.
When a setup returns to use after being inactive for one year or longer.
When anesthetic gas is smelled or personnel experience symptoms during or after use.
Following a spill, leak, control failure, concerning result, or other event for which EHS determines that monitoring is needed.

EHS evaluates results against the current American Conference of Governmental Industrial Hygienists (ACGIH) Threshold Limit Value appropriate to the anesthetic agent. ACGIH TLVs are health-based occupational exposure guidelines, not OSHA permissible exposure limits. EHS may also use task-specific data, direct-reading results, control performance, and other authoritative guidance when evaluating a setup and recommending corrective actions.

If monitoring is overdue, contact EHS promptly. EHS will review the setup and existing controls, prioritize monitoring, and advise whether interim measures or a pause in use is necessary. A monitoring result above an evaluation criterion does not by itself assign fault; it triggers evaluation and improvement of equipment, engineering controls, maintenance, or work practices, followed by verification as appropriate.

Personal Protective Equipment

Wear a lab coat or other protective garment, nitrile gloves, and safety glasses when handling liquid anesthetic agents or filling vaporizers.
Follow additional PPE requirements for the animal facility, clinical area, procedure, or other hazards present.
Standard PPE does not control anesthetic vapor exposure. Scavenging, local exhaust, equipment integrity, and safe work practices are the primary controls.
Respirators are not a substitute for required engineering controls and may be used only through Cornell’s Respiratory Protection Program when EHS determines they are appropriate.

Equipment Inspection and Maintenance

Inspect delivery and scavenging systems and perform the required leak or pressure test before each use.
Anesthesia machines, vaporizers, and scavenging systems must be inspected and serviced through Cornell’s Center for Animal Resources and Education (CARE) at the manufacturer-recommended interval and whenever a problem is identified. Contact CARE to arrange service.
CARE documents inspection, maintenance, calibration, certification, repairs, and removal of anesthesia machines, vaporizers, and scavenging systems from service. PIs and supervisors must retain or have access to the applicable service records.
Building ventilation and permanently installed local-exhaust systems must be evaluated or serviced through the responsible facilities unit, with EHS consultation as appropriate.
Contact EHS before returning a materially changed setup to routine use.

Spills, Leaks, Symptoms, and Incidents

Odor or suspected leak: If safe, turn off the vaporizer or gas source, stop the procedure, and prevent additional exposure. Leave the area if the source cannot be controlled safely. Notify the supervisor and EHS.
Symptoms: Move to fresh air, notify the supervisor, and obtain medical assistance appropriate to the symptoms. Call 911 for severe symptoms or a medical emergency.
Small spill inside a functioning chemical fume hood: Follow the laboratory- or unit-specific SOP and the safety data sheet only if trained and it is safe to do so.
Spill outside containment or uncontrolled release: Leave the area, prevent entry, and follow the emergency procedures for the location. Do not attempt cleanup unless trained, equipped, and authorized.
Reporting: Notify the supervisor and submit an incident report. Prompt reporting supports medical evaluation, equipment repair, and prevention of recurrence.

Transportation and Waste

Keep anesthetic-agent containers closed and transport them in a compatible, leak-resistant secondary container that can remain upright.
Use cushioning or dividers as needed to prevent containers from tipping or breaking.
Manage unused or expired anesthetic agents, spill debris, and used activated-charcoal canisters through Cornell’s hazardous-waste program.
Follow EHS instructions for empty anesthetic-agent containers; do not dispose of a container as ordinary trash unless it meets Cornell’s empty-container requirements.

Frequently Asked Questions

How do I know whether my monitoring is current?

Submit an askEHS request with the PI or unit, building, room, anesthetic agent, equipment, and scavenging method. EHS will check the monitoring record and help schedule monitoring if needed.

Should I contact EHS before buying or moving equipment?

Yes. Early review can prevent problems with equipment compatibility, exhaust connections, room ventilation, placement, and monitoring. Contacting EHS during planning is encouraged.

Does every anesthesia machine require separate monitoring?

EHS determines the appropriate monitoring strategy based on the setup. Equipment may be grouped only when the location, equipment, scavenging, procedures, and potential exposures are sufficiently similar to support representative monitoring.

What happens during monitoring?

EHS observes a representative procedure and selects methods appropriate to the question being evaluated. Sampling may be worn by a user, placed near a task, or performed with direct-reading equipment. EHS will explain the results and any recommended improvements.

Will asking EHS a question automatically stop my work?

No. Most questions can be addressed through consultation, review, or scheduled monitoring while work continues under existing controls. If EHS identifies an immediate or potentially serious exposure risk, EHS and the responsible unit will determine appropriate interim controls or whether the affected activity must pause.

Resources and Contact

Forms

Reproductive Health Questionnaire

Procedures

SOP For PI Self WAG Sampling

SOP for Safe Handling of Waste Anesthetic Gases (WAGs)

Contact Info