Abstract: An inhalation breathing apparatus is provided for administering a respirable fluid. The apparatus is a non-rebreathing face mask, conformable to the contours of an individual's face to enclose the nasal and oral cavities, and includes a source lumen for supplying a respirable fluid, a one-way valve to vent respirated fluid, a reservoir bag coupled to the source lumen and having a one-way valve allowing flow out of the bag and into the mask, and a substantially complaint tubular outer ring disposed on the lip of the mask. The outer ring may be fluid filled and provides a tight fluid seal around the nose and mouth, to prevent the entrainment of room air during administration of respirable fluids such as gaseous oxygen. The body of the mask may also include a number of small openings to allow for the flow of room air into the mask in the event of malfunction.