A method of charging fibrous webs with nonaqueous polar liquids. A web (20) that contains nonconductive fibers is wetted with a nonaqueous polar liquid (14). The web (20) is then substantially dried (22) to provide a fibrous electret web. The fibrous electret web can be used as a filter in a filtration face mask (40) that is adapted to cover the nose and mouth of the wearer. The present method has the advantage over known charging methods in that the nonaqueous liquid requires less energy for drying than is required for aqueous liquids. Additionally, many filter webs can be directly wetted with nonaqueous liquids, which cannot be easily wetted with aqueous liquids.