• What are waste anesthetic gases?
• What are some examples of anesthetic gases?
• What are the health effects of occupational exposure to waste anesthetic gases (WAGs)?
• How does exposure to WAGs occur?
• What are some measures for controlling exposure to WAGs?

What are waste anesthetic gases?

Healthcare workers in a variety of settings can be exposed to the anesthetic gases that leak out during medical procedures. These gases and vapours are known as waste anesthetic gases (WAGs).

Across Canada thousands of people who work in hospitals in areas such as operating rooms, recovery, and delivery rooms; dental offices; and veterinary clinics can be exposed to dangerous and harmful levels of waste anesthetic gases.

What are some examples of anesthetic gases?

The gases currently in use that are of concern are in Table 1.

What are the health effects of occupational exposure to waste anesthetic gases (WAGs)?

Effects of exposure to WAGs include dizziness, feelings of light headiness, nausea, fatigue, headache, irritability, and depression. Exposed workers can experience difficulty with cognitive, perception, and motor skills placing themselves and others at risk. Serious effects can also include sterility, miscarriage, birth defects, cancer, and liver and kidney disease in exposed workers and their spouses (in cases of miscarriages and birth defects).

How does exposure to WAGs occur?

Health workers can be exposed in a variety of ways.

• WAGs may escape during the initial hooking up and checking of the anesthesia system or the scavenging system.
• WAGs can escape from around the patient's anesthesia mask.
• The patient exhales WAGs; sometimes for days, after surgery.
• Leaks in the anesthesia system.
• When the system is purged at the conclusion of a medical procedure.

Surgery of the face, throat, and neck can lead to even greater leakage of WAGs for in these areas it is harder to control containment of the gases.

What are some measures for controlling exposure to WAGs?

An effective waste anesthetic gas management program includes:

• Engineering Controls,
• Work Practices,
• Air Monitoring and,
• Hazard Communication and Training.

Engineering Controls

A well-designed WAG scavenging system to collect, remove, and properly dispose of the gases - Care should be exercised so that the gases are not discharged near the near the air intake of the building or surrounding buildings.

• Properly designed masks such as the scavenging nasal mask - It should consist of a shroud large enough to capture gases exhaled from the patient's mouth. An inner mask is contained within a larger outer mask. A slight vacuum exists in the space between the masks.
  • The WAG scavenging system is the primary line of defense against exposure, however, a properly designed heating, ventilation, and air conditioning (HVAC) system can also help contribute to the dilution and removal of WAGs not collected by the scavenging system, that escape from leaks in the anesthesia equipment, or result from poor work practices.
  • The use of anesthetic respirators where appropriate.
  • Proper maintenance and inspection programs should be written and carried out for the WAG scavenging system, anesthesia machines, and the ventilation system. The scavenging system, anesthesia machines, and respirators must be checked daily for leaks and properly monitored.
  • Regular preventive maintenance should include inspection, cleaning, testing, lubrication, and adjusting of the components of the WAG scavenging system and the anesthesia systems. Damaged or worn out parts should be promptly replaced. Proper and posted documentation of the maintenance and preventive maintenance programs should be kept. Documentation should include the type of work performed and the date. It should also include the name(s) of the trained workers who serviced the equipment.

Work Practices

Proper work practices are a vital aid in reducing exposure of health care personnel to WAGs.

Improper anesthetizing techniques may include poorly selected, fitted or positioned face masks; an insufficiently inflated tracheal tube cuff; improperly connected tubes and fittings for the anesthesia machine; and not turning the gas off when the mask is removed from the patient's face.

Air Monitoring

One of the basic tools used to measure exposure to waste anesthetic gases is air monitoring. The information collected through air monitoring is critically important to the proper design and implementation of engineering controls and work practices.

Monitoring may be continuous or periodic but should adequately measure exposure in the exposed work areas and surrounding areas.

Monitoring can aid in identifying the presence and location of leaked gases and the effectiveness of corrective measures.

As most halogenated anesthetic gases cannot be detected by smell (unless they are in high concentration) proper monitoring becomes all the more critical.

Hazard Communication and Training

Employers should develop and implement a written hazard communication program regarding WAGs that includes description of the physical and health hazards of anesthetic agents in use, the compiling and availability of up to date material safety data sheets on all anesthetic gases employed; proper labeling of canisters, tanks, and containers; and a comprehensive employee training and information program.

The training program should list measures workers can take to protect themselves from the hazards of WAGs. The program should include information on steps taken by the employer such as engineering controls, clearly outline emergency procedures to contain spills, describe safe work practices and the use of any personal protective equipment, and detail the use of continuous monitoring devices.

The training program should clearly outline all methods and observable indicators that can detect the presence and release of anesthetic gases.

Spills of anesthetic agents must only be cleaned up and controlled by properly trained and equipped personnel.

In light of research indicating the teratogenic effect of WAGs and incidence of miscarriage, pregnant workers should be allowed to transfer to non-exposed areas.

Document last updated on April 29, 2002

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