Nitrous oxide

Scope

The anesthetic gases and vapors that leak into the surrounding room during medical procedures are considered waste anesthetic gases. It is estimated that more than 250,000 health care professionals who work in hospitals, operating rooms, dental offices and veterinary clinics, are potentially exposed to waste anesthetic gases and are at risk of occupational illness. The waste anesthetic gases and vapors of concern are nitrous oxide (N2O) and halogenated agents (vapors) such as halothane, enflurane, isoflurane, and desflurane. Some potential effects of exposure to waste anesthetic gases are nausea, dizziness, headaches, fatigue, and irritability, as well as sterility, miscarriages, birth defects, cancer, and liver and kidney disease, among operating room staff or their spouses (in the case of miscarriages and birth defects). Employers and employees should be aware of the potential effects and be advised to take appropriate precautions.

Regulatory citations

• 29 CFR 1910.105 — Nitrous Oxide
• Most other waste anesthetic gases are not specifically addressed in OSHA regulations. However, under the General Duty Clause of the OSH Act, employers have a responsibility to protect workers from serious and recognized hazards.

Key definitions

• Waste anesthetic gases: Waste anesthetic gases are small amounts of volatile anesthetic gases that leak from the patient’s anesthetic breathing circuit into the air of operating rooms during delivery of anesthesia. These gases may also be exhaled by patients recovering from anesthesia.

Summary of requirements

Employers can reduce exposures to waste anesthetic gases by taking the following steps, as recommended by NIOSH:

• Establish a hazard communication program.
• Install a scavenging system with the anesthesia delivery system to remove waste anesthetic gases from the operating room. Place the exhaust in an area where waste gases will not be reintroduced into intake air for the facility.
• Install a ventilation system that circulates and replenishes the air in operating rooms (at least 15 air changes per hour, with a minimum of 3 air changes of fresh air per hour).
• Install a ventilation system that circulates and replenishes the air in recovery rooms (at least 6 air changes per hour, with a minimum of 2 air changes of fresh air per hour) to prevent exposure to waste anesthetic gases exhaled by patients.
• Properly maintain anesthesia machines, breathing circuits, and waste-gas scavenging systems to minimize leaks of anesthetic gases into the operating rooms.
• Train all workers in hazard awareness, prevention, and control of exposures to waste anesthetic gases.
• Ensure workers wear respiratory protection when N2O concentrations are not consistently below 25 ppm. Practical considerations may prevent them from wearing such protection. Therefore, it is essential that employers use proper engineering controls and work practice controls.
• Develop a monitoring program supervised by a knowledgeable person in every operating facility.
• Keep good records of all collected air sample results for at least 30 years.
• Keep medical records of a worker’s exposure for 30 years after his or her employment has ended (see 29 CFR 1910.1020 — Access to Employee Exposure and Medical Records).
• Obtain baseline liver and kidney data for operating-room personnel and monitor their liver and kidney functions periodically.
• Record medical histories for workers and their families, including occupational histories and outcomes of all pregnancies of female workers and wives of male workers (if possible).