Moving filter device having filter elements with flow passages and method of filtering air

An air delivery device comprising a housing having an air inlet and an air outlet, between the air inlet and the air outlet is located an air delivery fan having at least two rotating air moving means, the rotating air moving means intersect the flow of air between the air inlet and the air outlet and establish a high pressure zone at the air outlet relative to the air inlet, the air delivery fan further comprising at least one porous filter element having at least one upstream filter face and at least one downstream filter face defining at least one primary flow channel, where the at least one upstream filter face rotates along the same axis of rotation as the air moving means and where the upstream filter face moves into a portion of the airflow through the air delivery fan such that the upstream filter face impacts a portion of the moving airflow in a flow channel, permitting the air to flow through the filter element from the upstream filter face to the downstream filter face and from the downstream filter face into a further portion of the airflow in a flow channel, the filter elements and/or air moving means further defining air flow passages allowing unrestricted airflow into and through primary flow channels to the air outlet, wherein the air filter elements comprise a filter of electret charged filter media having an average Frazier Permeability of at least 2000 m3/hr/m2.