A filtration system that rotates in conjunction with a blower wheel, and a method of attaching the same. The blower wheel typically has a plurality of fan blades arranged in a spaced relationship radially around a blower cavity to define a flow path extending radially outward from the blower cavity through the fan blades when the blower wheel is rotating. The filtration system includes a filter cartridge releasably attachable to the blower wheel in an engaged configuration. The filter cartridge includes a filter medium defining a generally center opening and a filter surface configured to be positioned generally adjacent to the fan blades and to extend across at least a portion of the flow path. In one embodiment, a plurality of flow passages extending through the filter medium.