A respiratory protective mask that prevents carbon dioxide rebreathing is disclosed. The respiratory mask includes a filter element that is dimensioned to cover an opening of a wearer's mouth. A cup like element is configured to rest against and retain the filter element against a wearer's chin. A top extent of the filter element extends laterally across a wearer's lip between a wearer's nose and the opening of the wearer's mouth, when worn. An arm of the filter element is defined by a convergence of the top extent and a lower extent of the filter element. The lower extent that converges upwardly from the cup like element towards a lateral end of the filter element subjacent to a wearer's ear, when worn. A retaining element is attached at the lateral end of the filter element and is configured to removably secure the filter element to cover the wearer's mouth.

The present application describes a unidirectional valve assembly (100) for a face mask, comprising a valve seat member (104) providing a continuous valve seat surface (156) surrounding a non-circular valve orifice (116), and a plurality of cross members (162) each extending partially across the valve orifice to meet at an intersection region; a substantially flexible and cantilevered valve flap (106) mounted at a fixed end region (108) to the valve seat member and configured to engage the valve seat when in a closed position to prevent air flow through the valve assembly; and a valve cover member (102) attached to the valve seat member and defining a plurality of apertures (178,180,182) in fluid communication with the valve orifice when at least a free end region (110) of the valve flap is in an open position with respect to the valve seat to allow air flow through the valve assembly, wherein the cross members (162) are arranged in a Y-shape configuration.