A pressure reducing valve for use in a system adapted to deliver a breathing gas to a patient. The pressure reducing valve is structured to communicate a flow of breathing gas to such a patient's airway during an inspiratory phase. The pressure reducing valve is structured to discharge the flow of breathing gas and a flow of exhaled gas to atmosphere during the expiratory phase. The flow of breathing gas and flow of exhaled gas are discharged to atmosphere through a number of exhaust ports. Because the flow of breathing gas and flow of exhalation gas are discharged through the exhaust ports, less effort is required by a patient during the expiratory phase.