Abstract: The seal is an elastic seal 100 that forms a sealing perimeter around the nose and mouth of a wearer. The elastic seal 100 comprises a first end 104 defining a first opening, a second end 108 defining a second opening in communication with the first opening, and a sidewall 112 extending between the first end 104 and the second end 108. The mask body 200 comprises a porous material. The mask body 200 is supported on the elastic seal 100 such that it covers the second opening of the elastic seal 100. The elastic seal 100 may comprise regions 114 distributed around a perimeter of the sidewall 112 and having a greater rigidity than a remainder of the elastic seal 100. The mask body may comprise a top panel 202 with one or more pleats 222.

Abstract: A semipermeable arrangement for use in clinical, agricultural, industrial and/or environmental settings. The semipermeable arrangement has a structural arrangement formed from a material such as ePTFE that has an affinity to a lubricating fluid such as perfluorocarbon. The structural arrangement may be infused with a lubricating fluid such that the semipermeable arrangement resists fouling. The semipermeable arrangement is further arranged with barriers to prevent or limit the movement of the lubricating fluid through at least part of the structural arrangement. The semipermeable arrangement further has passageways that are free from the presence of, and/or cannot be infused with, lubricating fluid. The passageways permit the movement of fluids such as air, water and dissolved substances through the structural arrangement. The semipermeable arrangement is thereby both self-cleaning and porous and has a wide range of uses.