Abstract: A method for filtering gas borne particles using a filter medium (13) in contact with a screen (14) composed of polymeric strands (30, 31) is described. The method is characterized by the fact that the filter medium flutters on the surface of the screen because of flow of the gas along the surface of the filter medium to generate an electrostatic charge in the medium which attracts the particles to the filter medium. Particles 0.1 micron and larger in the gas can be removed by the method.

Abstract: A gas borne particle filtering apparatus having a filter medium (13) with inlet and outlet openings (11, 12) in a staggered sawtooth cross-sectional configuration (140, 141) in a casing (10) for the filter medium positioned such that the gas passes along and between the sawteeth on both sides of the filter medium is described. A screened belt or support (14) for the filter medium is described. The apparatus is particularly suited to cleaning heated or cooled air in a confined work space in a factory containing small micron sized particles so that the air can be recycled.