[Anesthetic gases, the ozone layer and the greenhouse effect. How harmful are the anesthetic emissions for the global environment?].

During the last decade, world society has acknowledged the harmful effects on the environment of the greenhouse effect and of depletion of the ozone layer, caused by industrial emissions of man-made compounds. Ozone depletion is caused mainly by chlorine compounds or nitrogen oxides released by degradation in the stratosphere. The greenhouse effect is caused by increased trapping of terrestrial heat radiation. Degradation of the anaesthetic vapours halothane, enflurane and isoflurane releases chlorine, and nitrous oxide degradation produces reactive nitrogen oxides. Nitrous oxide in particular, but also the vapours, absorb terrestrial radiation. The total discharge of anaesthetic vapours contributes to less than 0.01% of the total atmospheric chlorine load, and the annual Norwegian release of approximately two tons accounts for 0.2% of the world total. It is estimated that the total amount of nitrous oxide released from anaesthetics accounts for 0.05% of the greenhouse effect, while annual Norwegian emissions of nitrous oxide (less than 160 tons) comprise 0.2-0.4% of world total. Because of their favourable clinical properties and their modest contribution to ozone depletion and the greenhouse effect, medical use of inhalational anaesthetic agents should not be banned. However, low flow anaesthetic techniques should be employed, in order to reduce their negative impacts on the atmosphere.