Abstract: An apparatus is provided for supplying a constant predetermined concentration of a predetermined gas at the ingress area of a living body, such as the nose and mouth of a human being, which includes an adjustable support adapted to be fixed to the person's head, and the support mounts a nozzle head. The nozzle head includes a plurality of nozzles spaced about an axis of the nozzle head. The nozzle head is spaced from the nose and mouth area such that ready unimpeded access to the nose and mouth area is obtained. Means are provided for supplying the gas under pressure through the nozzles. The nozzle head and adjustable support means are adapted for adjustment such that the axis of the nozzle head passes through the center of the ingress area formed by the nose and mouth of the person, and each nozzle is projected at a small angle to the axis so as to form a pressurized cone of the gas towards the ingress area of a person.