Flat-fold respirator

A personal respiratory protection device comprising:

• an upper panel,
• a central panel, and
• a lower panel,
• the central panel being separated from each of the upper and lower panels by a first and second fold, seam, weld or bond, respectively, such that the device is capable of being folded flat for storage along the first and second fold, seam, weld or bond and opened to form a cup-shaped air chamber over the nose and mouth of a wearer when in use,
• wherein the lower panel includes a stiffening sheet that has a longitudinal crease line and a lateral crease line, and
• wherein the stiffening sheet has an hour-glass shape and comprises a first pair of wings, a waist portion, a second pair of wings, and a front section, and wherein the stiffening sheet is folded about the longitudinal crease line when the device is in use and folded about the lateral crease line when the device is in a flat folded configuration.