An apparatus for irradiating air in an air circulation system of a vehicle, the apparatus comprising: a filter unit for coupling to a recirculating air conduit of the air circulation system, the filter unit having an inlet end; a filter disposed in the inlet end of the filter unit, comprising an outer High Efficiency Particulate Air (HEPA) media filter, and an inner activated carbon filter defining an interior volume of the filter; a plurality of ultraviolet light transmissive strands that each have distal ends disposed in a spaced apart manner in an interface region between the outer HEPA media filter and the inner activated carbon filter, and proximal ends configured for connection to an ultraviolet light emitting source such that ultraviolet light is transmitted by the plurality of ultraviolet light transmissive strands into the interface region between the outer HEPA media filter and the inner activated carbon filter; and an end plate disposed over an open end of the filter, having an aperture though which the plurality of ultraviolet light transmissive strands extend; and wherein the ultraviolet light transmissive strands are configured to receive ultraviolet light emitted by the ultraviolet light emitting source that is substantially between 222 nm and 265 nm, and to transmit the ultraviolet light into the air passing through the interface region between the outer HEPA media filter and the inner activated carbon filter and into the air circulation system; and each of the distal ends of the plurality of ultraviolet light transmissive strands are of varying lengths, such that the distal ends are positioned at different locations within the interface region between the outer HEPA media filter and the inner activated carbon filter. a filter unit for coupling to a recirculating air conduit of the air circulation system, the filter unit having an inlet end; a filter disposed in the inlet end of the filter unit, comprising an outer High Efficiency Particulate Air (HEPA) media filter, and an inner activated carbon filter defining an interior volume of the filter; a plurality of ultraviolet light transmissive strands that each have distal ends disposed in a spaced apart manner in an interface region between the outer HEPA media filter and the inner activated carbon filter, and proximal ends configured for connection to an ultraviolet light emitting source such that ultraviolet light is transmitted by the plurality of ultraviolet light transmissive strands into the interface region between the outer HEPA media filter and the inner activated carbon filter; and an end plate disposed over an open end of the filter, having an aperture though which the plurality of ultraviolet light transmissive strands extend; and wherein the ultraviolet light transmissive strands are configured to receive ultraviolet light emitted by the ultraviolet light emitting source that is substantially between 222 nm and 265 nm, and to transmit the ultraviolet light into the air passing through the interface region between the outer HEPA media filter and the inner activated carbon filter and into the air circulation system; and each of the distal ends of the plurality of ultraviolet light transmissive strands are of varying lengths, such that the distal ends are positioned at different locations within the interface region between the outer HEPA media filter and the inner activated carbon filter.