Current Regulatory Status
DHHS (NIOSH) Publication No. 94-100 & 94-118, APRIL 1994
"CONTROLLING EXPOSURES TO NITROUS OXIDE DURING ANESTHETIC ADMINISTRATION"
WORKERS EXPOSED TO NITROUS OXIDE (N2O) MAY SUFFER HARMFUL EFFECTS.
The National Institute for Occupational Safety and Health (NIOSH) has issued a warning to professionals who work with nitrous oxide (N2O). The Institute warns that even with preventive measures such as scavenging systems in place these workers may be at risk for serious health effects due to their exposure. Workers and employers should take the following steps to reduce N2O exposure in the workplace:
NIOSH has requested that these additional steps be followed:
- Monitor anesthetic equipment when installed and every three months thereafter:
- Leak test equipment
- Monitor air in the worker's personal brrreathing zone
- Monitor the environment (room air)
- Prevent leakage from the anesthetic delivery system through proper maintenance and inspection of equipment. Eliminate or replace the following:
- Loose-fitting connections
- Loosely assembled or deformed slip joinnnts and threaded connections
- Defective or worn seals, gaskets, breattthing bags, and hoses.
- Control waste N2O with a well designed scavenging system that includes the following:
- Securely fitting masks
- Sufficient flow rates (i.e., 45 liters per minute) for the exhaust system
- Properly vented vacuum pumps
- Make sure that the room ventilation effectively removes waste N2O. If concentrations of N2O are above 25 ppm, take the following steps:
- Increase airflow into the room
- Use supplemental local ventilation to cccapture N2O at the source
- Institute an educational program that describes N2O and defines prevention measures.
- Institute a worker education program that:
- describes standard operating proceduresss for all tasks that may expose workers to N2O
- informs workers about proper work practttices, controls, equipment, and protective gear that should be used when working with N20.
- Prepare a written monitoring and maintenance plan for each facility that uses N2O. This plan should be developed by knowledgeable persons who consider the equipment manufacturers' recommendations, frequency of use, and other circumstances that might affect the equipment.
- Check all rubber hoses, connections, tubing, and breathing bags daily and replace them when damaged or when recommended by the manufacturer.
- Following visual inspection, perform leak testing of the equipment and connections by using a soap solution to check for bubbles at high-pressure connections. For a more thorough inspection of all connectors, use a portable infrared spectrophotometer calibrated for N2O detection [NIOSH 1984].
- Check both high- and low-pressure connections (such as 0-rings) regularly, as they may become worn; replace them periodically, according to the manufacturer's recommendations.
- Ensure that gas cylinders are safely handled, used, and stored as specified by the National Research Council [NRC 1981] and as required by OSHA [29 CFR 1910.101].
- Inspect the anesthetic delivery systems and all connections before starting anesthetic gas administration. Make sure that breathing bags, hoses, and clamps are in place before turning on the anesthesia machine.
- Do not turn on the machine delivering N20 until the vacuum system scavenging unit is operating at the recommended flow rate of 45 L/min.
- Fasten the mask according to the manufacturer's instructions to prevent leaks around the mask during gas delivery.
- Flush the system of N2O after surgery by administering oxygen to the patient through the anesthetic equipment for at least 5 minutes before disconnecting the gas delivery system.