N95 masks, called that because they filter out 95 percent of particles smaller than .3 microns, represent a tricky production problem. They must sit snug enough to create a seal and fit to the individual’s face. The masks consist of two layers of cloth with a piece of melt-blown polypropylene in between. The polypropylene is extruded at extremely small diameters, then settles and cools in a random pattern. The fibers are electrically charged, attracting particles while allowing air to pass through. - [12]
