Ambient air contamination in a dental outpatient theatre.

The extent of air contamination by halothane in an operating session was correlated with the number of patients, the total usage of halothane, refilling a vaporizer and the number of hyperventilating patients per session. Trichloroethylene content of theatre air correlated only with total usage and refilling a vaporizer. A very strong personal association (P smaller than 0.001) was found between the anaesthetist and the extent of air contamination with halothane. The association was weaker (0.05 less than P less than 0.1) for trichloroethylene. The median ambient air contamination with halothane in the vicinity of the faces of anaesthetists and dental surgeons was between six and nine times greater than the median air contamination at the fixed sampling sites (P smaller than 0.005).