Method of making a filtering face mask that has an exhalation valve attached thereto

A method for making a filtering face mask that comprises providing a fluid-permeable multi-layered mask body comprising a structural supporting layer and a filtration layer, the multi-layered mask body being configured to fit over the nose and mouth of a person and having an aperture disposed therein; providing an exhalation valve comprising a base portion and a deformable hollow plastic extension member that extends from the base portion to a tip; inserting the tip through the aperture; and deforming the extension member so as to make an effective seal between the exhalation valve and the mask body.