Thermocamera studies of enflurane and halothane vapours

The ability of enflurane and halothane to absorb infra-red (IR) energy was used to visualize their vapours; IR radiation was emitted by a heated screen and the absorption was studied with an IR camera. Even small concentrations of enflurane (0.2 vol %) and halothane (0.5 vol %) could be detected when released into the operating room atmosphere. Enflurane and nitrous oxide were dispersed in a similar way when they leaked from the face mask. Thus when anaesthetic pollution is monitored in the operating room, measurements of the concentration of nitrous oxide are sufficient for routine purposes. The IR method has added a new dimension to the study of occupational exposure to otherwise invisible gases.