Nitrous oxide scavenging in dental surgery. I. A comparison of the efficiency of different scavenging devices.

Chronic exposure of dental personnel to trace concentrations of nitrous oxide has been reported to constitute a health hazard. During the dental treatment under nitrous oxide-oxygen sedation dentists are frequently exposed to as much as 1000 ppm of nitrous oxide. Nitrous oxide-oxygen sedation equipment with scavenging devices for removal of expired and excess gases is available. The aim of this study was to determine the efficiency of different scavenging devices by means of a standardised experimental model and thereby study occupational nitrous oxide exposure in dental surgery. Seven commercially available breathing systems were studied. The experimental model of measuring occupational nitrous oxide exposure during a 25-minute standardised dental treatment showed high reproducibility and might be useful for determining whether or not a system has a reasonable chance of meeting the requirements set by different national boards of occupational safety and health. The scavenging efficiency of the different systems tested varied. According to this method of evaluation, five out of seven systems might have good possibilities of meeting Swedish standards of occupational exposure (nitrous oxide limit value 100 ppm).