Abstract: A unidirectional valve for use with a filtering face mask. The valve can include a flap, and a valve seat. The flap can be cantilevered and can flex away from a seal surface of the valve seat to an open position. The valve can further include a housing that at least partially covers the valve seat and the flap. In some embodiments, the height of the housing is no greater than about 1.25 cm, while the distance between the flap and the seal surface when the flap is in the open position is at least 0.35 cm. A projection can be coupled to an inner surface of the housing, and the height of the projection can generally decrease toward the front of the housing. In some embodiments, the projection can have a profile that substantially follows the profile of the flap when the flap is in the open position.

Abstract: A respirator 10 that comprises a mask body 32 and a nose foam 10. The mask body 32 is adapted to fit over the nose and mouth of a person and has an interior surface 34. The nose foam 10 has a rear side 24, a front side 26, a rear side 24, and is secured to the interior surface 34 of the mask body 32 at a mask contacting surface 12. The nose foam 10 also has a central portion 14 and first and second side-contacting portions 16 and 18 that are symmetrically located on opposing sides of the central portion. The nose foam further has a nose-contacting surface 20 that extends over the central portion 14 and the first and second side-containing portions 16, 18. The nose-contacting surface 20 is skewed at first and second angles ? to a plane 22 that cuts through the nose foam orthogonally to its lengthwise dimension. A nose foam of this construction can provide a snug fit to a wearer's face in the nose region without having to use a nose clip.