Exposure to nitrous oxide in a paediatric dental unit

Objective.  The aim of this study was to evaluate the 8-h time-weighted average (8-h TWA) exposure to nitrous oxide of dentists working in a paediatric dental unit, and to relate this to various operator, patient and environmental factors. Methods.  This prospective, open-label study monitored nitrous oxide levels using either a personal dosimeter or an electronic sensor worn by the operator. Information was recorded by three dental operators administering nitrous oxide/oxygen for inhalational sedation. Thirty-four paediatric dental patients were treated over a total of 17 treatment sessions. Results.  Active scavenging was used for all children; 23 were treated using the Porter-Brown scavenging system and 11 with the Accutron system. Exposure to nitrous oxide expressed as an 8-h TWA ranged from 16 to 374 ppm, with a mean of 151 ppm. The recommended 8-h TWA of 100 ppm was achieved in only 38% of cases. Ambient nitrous oxide levels apparently increased with restorative treatment, poorer behaviour, when the extractor fan was switched off, with patients over 10 years of age and an increased number of sequential patients. Conclusions.  This study found that the recommended 8-h TWA was achieved in only 38% of treatment episodes, despite the use of active scavenging.