An aerosol medication delivery system includes a holding chamber having an output end with a plurality of tabs extending from an exterior. A patient interface includes a housing having an annular attachment collar configured with a plurality of openings receiving the plurality of tabs. The housing has a plurality of engagement members formed on an interior of the housing and an interior wall defining a sealing surface. A retaining ring is engaged by the engagement members and is coupled to an interior of the housing. A one-way inhalation valve includes a non-moveable annular valve seat engaged by the retaining ring and the sealing surface of the interior wall. A one-way exhalation valve is formed separately from the one-way inhalation valve, and is coupled to the patient interface.
