US Patent 7013896 Mask with inhalation valve

A mask for use in inhaling a substance includes a mask housing defining a chamber. The housing has an inlet and an outlet communicating with the chamber. A valve is disposed in the inlet and is integrally formed with the housing, such that the valve and the housing are formed as a one-piece unit. In a preferred embodiment, the housing further comprises an exhaust port and an exhalation valve disposed in the exhaust port, with a shield disposed around the exhaust port. In another aspect, a method of manufacturing a mask also is provided.