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The reduction of pollution

This paper describes the construction and evaluation of a simple anti-pollution device for use with the McKesson nasal mask for dental anaesthesia. The device is attached to the expiratory valve of the mask and spilled halothane vapour is adsorbed onto activated charcoal. In theatre use, comparing similar dental anaesthesia sessions, it resulted in a reduction of approximately 78% in the mean halothane concentration (vol./vol.) at a point equidistant from the expiratory valve as the faces of surgeon and anaesthetist. This percentage reduction was consistent with the weight gained by the activated charcoal container (Cardiff 'Aldasorber') compared with the weight of halothane vapourised.