Reduction of nitrous oxide contamination in a paediatric hospital.

Ambient nitrous oxide concentrations were recorded in an operating room during delivery of the gas at low and medium flow-rates, with and without the application of simple scavenging devices. Residual background levels of nitrous oxide were still present more than one hour after disconnection of the flowmeters and use of the room. Scavenging reduced concentrations ten-fold. Adjacent corridors and the post-anaesthetic recovery room were contaminated with nitrous oxide from the operating rooms and from patients. A vigorous programme of checking for leaks and repairing and maintaining equipment, coupled with the use of suction scavenging, can reduce atmospheric contamination with nitrous oxide below 30 p.p.m., which is well within the limit suggested by the U.S. National Institute for Occupational Safety and Health.