Anesthetic gases and vapors that leak into the surrounding room are considered waste anesthetic gases (WAGs). If equipment is not set up or functioning properly or if the WAG is not properly exhausted or captured via scavenging, or if ventilation not adequate, healthcare workers, researchers, and veterinary staff may be exposed to WAGs. This exposure creates a risk of potentially developing adverse health effects.
Environmental Health & Safety (EH&S) provides the Anesthetic Gases: Safe Use Guidelines to help users of anesthetic gases understand the potential health effects from exposure and provide guidance to minimize potential exposures.
Exposure to WAGs
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Managers, supervisors, principal investigators, and responsible parties ensure the safety of workers, patients, researchers and research subjects by implementing safe work practices that control exposure to WAGs, including training personnel, and ensuring machines, equipment, and ventilation systems used with anesthetic gases are maintained and inspected on a regular basis.
Potential exposure to WAGs at UW could occur in the following settings:
- UW Medicine operating rooms or other clinical applications with anesthesia
- School of Dentistry facilities and UW Medicine-affiliated dental clinics
- Department of Comparative Medicine (DCM) facilities (vivaria)
- Washington National Primate Research Center (WANPRC) facilities
- Research laboratories working with animals
Exposure to nitrous oxide and halogenated anesthetic gases can result in reproductive, neurological, psychological, and other health effects.
Exposure control methods
Methods to control exposure to WAGs include the following:
Engineering controls: Includes general and local exhaust ventilation, scavenging systems, and key fill bottle adapters
Work practices: Document safe work practices in standard operating procedures that include transporting chemicals safely, conducting leak testing, pre-anesthesia checkout, preventive maintenance of machines and systems.
Administrative controls: Train all personnel before starting work in hazard awareness, prevention, and controls used to prevent exposures to anesthetic agents and WAGs.
Personal protective equipment: Standard personal protective equipment (PPE) worn in a clinical or laboratory setting must be worn when working with anesthetic agents; however, exposure to WAGs is not effectively reduced by gloves, goggles, and surgical masks.
Review the Anesthetic Gases: Safe Use Guidelines for information on implementing exposure control methods.
What you can do to stay safe
- Review the roles and responsibilities listed in the Anesthetic Gases: Safe Use Guidelines.
- Provide the required site-specific training on hazard communication and exposure risk mitigation strategies.
- Implement exposure control methods.
- Document work practices in standard operation procedures.
- Perform leak testing, pre-anesthesia checkout, and preventive maintenance of machines/systems.
- Properly dispose of expired or unwanted anesthetic gas or liquid containers, used charcoal canisters, and gas canister/cylinders.
Emergency response and reporting
If a spill or release occurs, stop work.
- For large spills, evacuate the area and call 9-1-1 on any campus phone for help, or follow your facility-specific procedures for chemical spill response.
- If an exposure occurs, follow the procedures in the EH&S posters for Spill Response and Exposure Response.
Refer to the Anesthetic Gases: Safe Use Guidelines for more information on spill cleanup and exposure incidents. For questions on spill cleanup, contact EH&S Spill Advice at 206.543.0467.
UW personnel are required to submit an incident report to Environmental Health & Safety for any work-related event that results in an injury, illness, exposure to hazardous materials, property damage, or fire, regardless of the work location. UW personnel are highly encouraged to submit work-related near-miss events. Visit the Incident Reporting page for more information.
UW Medicine personnel follow UW Medicine incident reporting procedures.
Services available
Environmental Health & Safety (EH&S) provides the following services:
- Assist University departments, units, and organizations with training personnel on the hazards of anesthetic gases, engineering controls, safe work practices, procedures to avoid exposures, and proper PPE to wear.
- Reviews ventilation in research spaces where anesthesia will be used.
- Conduct personal or area air monitoring and testing as needed.
- Collect expired or unwanted anesthetic gas or liquid containers and used charcoal canisters.
- Consult on leak testing as needed.
- Evaluate anesthetic gas SOPs, gas use, systems, and potential personnel exposures.
Contact
Call EH&S at (206) 543-7388 for information on:
- Exposure concerns to anesthetic gases
- Leak testing
- Review ventilation in spaces where anesthesia will be used
- Air monitoring
Call EH&S Spill Advice at (206) 543-0467.
Contact UW Employee Health Center to consult with an occupational medical professional regarding anesthetic gas exposures.
About
One of the principal goals of general anesthesia is to prevent patients, both human and animal, from feeling pain during surgery. A common method of anesthesia is the purposeful inhalation of a gas that is known to provide general sedative effects and/or induce unconsciousness. These gases can be separated into two categories: Halogenated anesthetic gases/vapors and nitrous oxide. These may be administered in combination to produce surgical levels of anesthesia. Halogenated anesthetic gases/vapors and nitrous oxide are also commonly used during veterinary care or experiments in animal research.
Frequently asked questions
Exposures can occur when handling the gases or liquids, leakage from equipment, from the patient or animal breathing circuit during delivery of anesthesia, or as exhaled by the patient or research animal (e.g., during recovery).
Workers may be exposed to waste anesthetic gases when:
Clinical/dental
- When leaks occur in the anesthetic breathing machine, breathing system, hoses, and connections; this happens if the connectors, tubing, and valves are not maintained and/or tightly connected.
- When anesthetic gas seeps over the lip of the patient’s mask or from endotracheal coupling, particularly if the mask is poorly fitted (e.g., during pediatric anesthesia)
- During dental operations, especially with patient mouth-breathing or talking
- Leaks from around tracheal tubing
Animal
- During induction of anesthesia, both while using liquid anesthetics (drop method) and induction boxes; this is more common with rodents.
- Opening of induction boxes
- Failure to promptly discontinue the flow of anesthetic gas prior to removing an animal from an anesthetic breathing line (e.g. removing and replacing animals on a single nose cone)
- Misuse or over-saturation of charcoal canister in scavenging system
All applications
- When anesthetic gases escape during hookup and disconnection of the anesthesia system or scavenging system
- When filling refillable vaporizers
- Leaks between subject and facemask/nose cone
- Spills of liquid anesthetics
- When the anesthesia system is flushed or purged at the conclusion of a procedure
- Insufficient ventilation system or gas scavenging system
Anesthetic gases must always be used in a well-ventilated room (greater than or equal to six (6) air changes per hour) with no recirculation of locally exhausted air.
Anesthetic gases must always be used with a scavenging/ventilation mechanism that eliminates inhalation exposure to the worker.
Clinical workers who may be exposed to anesthetic gases include:
- Anesthesiologists
- Nurse anesthetists
- Dentists
- Dental assistants
- Dental hygienists
- Operating-room nurses
- Operating-room technicians
- Other operating-room personnel
- Recovery-room nurses
- Other recovery-room personnel
- Surgeons
In animal research environments, the following workers may be exposed to anesthetic gases:
- Research staff
- Veterinary staff
- Animal care technicians
Most anesthetic gases have high odor thresholds. This means that anesthetic gases cannot be detected by their odor until concentrations are very high. For example, halothane cannot be detected by 50% of the general population until the concentration is more than 125 times the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit. Therefore, workers should never rely on odor as a warning of potential exposure to anesthetic gases.
Specific anesthetic gases and liquids used at UW are listed below. At room temperature, nitrous oxide is a gas. Mixed with oxygen, it is commonly used for sedation and pain relief in dentistry. The halogenated anesthetic agents are volatile liquids that are vaporized and mixed with other gases prior to inhalation by the patient or subject before or during surgery. Other gas mixtures always include oxygen or air but may also include gases such as nitrous oxide.
- Nitrous oxide
- Isoflurane
- Halothane
- Desflurane
- Sevoflurane
Washington state has established permissible exposure limits for nitrous oxide (WAC 296-841-20025). Recommended exposure limits were established (1977) by NIOSH and the American Conference of Governmental Industrial Hygienists (ACGIH) (1989) for nitrous oxide and certain halogenated anesthetic gases. Refer to the document Anesthetic Gases: Safe Use Guidelines for more information.
The specific health effects for nitrous oxide and the halogenated anesthetic gases are summarized below. An acute exposure is defined as a short-term exposure (i.e., minutes to days) to a relatively high concentration of an anesthetic gas. A chronic exposure includes long term exposures (i.e., months to years) to relatively low concentrations of anesthetic gases.
Nitrous Oxide
Acute exposure can cause:
- Lightheadedness
- Shortness of breath
Chronic exposure has been linked to:
- Reduced fertility
- Spontaneous abortion
- Birth defects
- Reproductive harm
- Neurologic disease
- Liver/kidney disease
Halogenated Anesthetic Gases
- Acute exposure can cause:
- Headache
- Drowsiness
- Nausea
- Dizziness
- Fatigue
- Irritability
- Transient blurring of vision
- Difficulties with judgement and coordination
- Liver and kidney disease
Chronic halogenated anesthetics exposure has been linked to:
- Sterility
- Miscarriages
- Birth defects
- Genetic damage
- Cancer
- Liver and kidney disease
- Asphyxia
Refer to the Anesthetic Gases: Safe Use Guidelines for more information.