A non linear, medicated aerosol holding and delivery chamber without sealing valves at the aerosol inlet and outlet ends. There is a low pressure actuated, vacuum relief, drain check valve at the bottom end of the chamber and an overpressure relief valve at the top end adjacent the mouthpiece opening. The vacuum relief, drain check valve has a radial support plate beneath it that allows for the creation of a vortex in the aerosol plume. The drain check valve also provides for the complete return of any condensed aerosol to the nebulizer when closed. The overpressure relief valve efficiently allows dispelling of the patients air. Both valves aid in the decrease of the MMAD of the medicated aerosol particles. There is no truly enclosed volume defined by the body of the chamber as the mouthpiece is open into the top of the chamber body, free of any valves.
