Nitrous Oxide Hazards and Proper Use College of Dental Medicine

What is Nitrous Oxide? Nitrous oxide (N20) is nonflammable, colorless gas with pleasant, sweet odor and taste Also called dinitrogen monoxide or laughing gas When inhaled, it produces relaxation, and a reduced sensibility to pain

Uses Anesthetic agent in dental, medical and veterinary operations Analgesic agent for conscious sedation in dental operations Other uses include foaming agent for whipped cream and component of rocket fuels

Exposure Routes & Safe Limits Inhalation – common exposure route Dermal – in liquid form NIOSH: 25 ppm time-weighted average for duration of use ACGIH: 50 ppm time-weighted average for 8 hour of use

Metabolism Mixed with oxygen for surgical anesthesia Absorbed by diffusion through inhalation Eliminated through respiration Elimination half-life is ~ 5 minutes Minimally metabolized through excretion

Health Effects Exposure to high concentrations may cause Acute Effects: Breathing difficulty and asphyxia from abuse by inhalation Nausea or Headache Vitamin B12 interference Frostbite in liquid form Chronic Effects: Megaloblastic bone-marrow depression Neurological symptoms Adverse reproductive effects

Potential for Exposure in Dental Clinics Inadequate Ventilation Systems Inadequate Scavenging Systems Equipment Malfunction Equipment failure Leaks due to poor connections Poor Technique or Use Uncooperative Patient

Exposure Controls Engineering Controls General room ventilation provides 12 air changes per hour hence keeping the Nitrous Oxide concentration <25ppm Scavenging system used when administering N2O captures all exhaled and unused gas and keeps out of the office area thereby protecting you Report any damage and non-functional scavenging and ventilation systems

Exposure Controls Proper work practices, training, patient and equipment management are part of administrative controls and contribute to controlling N2O exposure to you Inspect delivery system prior to N2O administration Check connections, breathing bags, hoses and clamps. Do not fill breathing bag to capacity Over inflation can cause excessive leakage from the mask The bag should collapse and expand as the patient breathes Flush the system of N2O after the procedure by administering O2 to the patient for five minutes before disconnecting the gas delivery system Improper Fit Proper Fit

Exposure Assessments Surveys performed by consultant to ensure systems are working properly and- Nitrous oxide levels are < 5ppm Air changes are adequate (> 10ACH) in rooms All rooms are confirmed to be under negative pressure

occusafety@columbia.edu