New filtering material comprised by a needled felt of synthetic curled macro fibrilae, obtained by fibrilation of a laminated film with two olefine components of different natures, and subjected to a thermal treatment; said fibrilae having a rectangular cross section area and a titre comprised between 8 and 20dtex. Respiratory mask comprised of three shells (CI.MF.CE) of different shapes, the intermediate shell (MF) being made with the present new material and enclosed between the two outer shells welded thereon (SUS) at the periphery thereof, the marginal portion (A) of the intermediate shell (MF) filling a groove of the inner shell (CI) to form a bead (BR).