Abstract: A nonwoven filter media or mat (1) formed from a plurality of elongated generally hollow fibers (20) each having an internal cavity (22) which has an opening (24), smaller than the cavity width, to the fiber (20) surface and each retaining within its internal cavity (22) an electrically chargeable powder particle material. The electrically chargeable material can be a pure electrically chargeable dielectric powder material or a mixture of oppositely chargeable dielectric powder particles (18). The small solid particles (18), which can be PTFE, CTFE, halogenated polymers or any other electrically chargeable dielectric powder particles, are permanently entrapped within the longitudinal cavities (22) of the fibers (20) without the use of an adhesive.