Abstract: An electrically operated cleaner to remove dust, pollen, smoke, etc. from the air in the nature of an electrostatic precipitating apparatus is shown. It is suitable for general utilization including furnace or air conditioner mounting. An operating unit is adapted to be removably carried within a frame-like housing which is open from its opposite wide sides for fluid or air movement therethrough, and which is electrically energized through the agency of a power pack to supply energy of one potential to a row of spaced-apart cell-defining plate members and to supply energy of opposite potential to in-between-spaced ionizing wires of one or more wire rows. A plate row of continuous construction is, in one embodiment, contoured for more efficient air through-flow cleaning action in one direction than the other, and in other embodiments is contoured for substantially equal efficiency of through-flow cleaning action from either open side of the apparatus.