the present invention provides an anti - pathogenic air filtration medium comprising a fibrous substrate whose fibers are coated with coating comprising a polymer . the coating provides an environment that is destructive to airborne pathogens . in particular , the filter medium can be used in a building air handling system that both filters the air and eliminates pathogens . the filter medium also can be used to create a new bio - protective gas mask that not only offers protection against chemical warfare agents , but also provides protection against biological pathogens .