Microbicidal air filter for use with an air passageway, which includes an immobilization network including a plurality of fibers having an amount of at least one antimicrobial agent incorporated and molecularly bonded into a structure thereof sufficient to substantially immobilize, retain and at least inhibit the growth of, or typically kill, microbes suspended in a volume of air moving through the air passageway. The immobilization network is substantially permeable to air. A microbicidal facemask and a microbicidal air filter used in an air circulation system using the immobilization network are disclosed.