An apparatus for clearing ventilating systems of grease vapors, odors, smoke and the like which comprises a housing having inlet and outlet passages and enclosing between these passages, sequentially in the direction of air flow, a centrifugal extractor thereby substantially reversing the airstream flow, a continuous cold water spray intersecting and directed counter to the airstream flow and a group of electrostatic precipitators. The combined action of the extractor, water spray and precipitators remove variously sized grease, vapor and smoke particles from the ventilating airstream.