A simple device designed to protect operating theatres against atmospheric pollution by volatile anaesthetics.

The authors worked out and applied a new device of positive pressure valve encased in the rebreathing circuit and one-way Ruben's valve, as well as a modification of Rees's system making it possible to conduct excess gases containing anaesthetics outside the operating theatre. These devices and modifications are completely reliable owing to their simplicity and their construction is cheap. They effectively reduce the degree of atmospheric pollution in the operating theatre with anaesthetics used in inhalation anaesthesia. They may be applied to every type of apparatus used for general anaesthesia.