A mask for delivery of oxygen to a patient, comprising a body having a rim to contact a patients face, a mask body and a diffuser having a base, and wall circumscribing a central oxygen delivery aperture extending through the central portion between the inner surface and the outer surface, the wall and base configured to act as an oxygen diffuser to a plume of diffused oxygen generally towards the patients nose and mouth with substantial opening in the mask body to permit the patient to carry out normal functions.
