Intra-nasal filter devices and methods for their manufacture and use are disclosed. An intra-nasal filter device includes: a first stage filter proximate the septum; and a second stage filter comprising a flexible material extending upwardly from the first filter stage filter; wherein the flexible material comprises: an impedance in the range of 0.02 to 0.2 cmH.sub.2O; an effective cross-sectional area in the range of 0.2 to 2 square inches; and a plurality of radially extending geometric structures disposed along an axial length of the second stage.

A mouth-nose mask for reducing the transmission of pathogens via droplets of secretion is disclosed. The mouth-nose mask includes a central fold which defines a chin-nose line of the mouth-nose mask and separates the mouth-nose mask into two substantially congruent halves. A fastening means for fastening the mouth-nose mask to a wearer's ears or back of the head is attached to the ends of the two halves remote from the central fold. The mouth-nose mask includes at least two superposed layers of a filter material, the at least two layers defining the outer shape of the mouth-nose mask and being only partially joined to one another at their edges.

A filter (1) includes a filter element (2) having a filter member (10) with a tubular shape disposed on the outer side of a porous tube (7), and the filter member (10) includes an embossed portion (21) formed on a surface of the filter member (10).

Filter media and filters are provided having a fibrous web including first and second dissimilar electret fibers ultrasonically bonded to each other. The first and second electret fibers may be directly bonded to each other without needle punching, which substantially maintains the thickness or loft of the fibrous web of the filter media and filters. Maintaining the thickness or loft of the fibrous web during the bonding process decreases the pressure drop across the filter media and increases its dust holding capacity. Medical grade filters and/or self-supporting (i.e., self-pleatable) air filters are also provided. The medical grade filters and/or self-supporting air filters may include one or more support layers ultrasonically bonded to the fibrous web or fiber layers without needle punching, which maintains the stiffness of the support layers and allows the filter to be produced in a single manufacturing step.