Abstract: A toilet seat for filtering foul air includes large capacity internal ducting connected between a very large intake opening and a large exhaust for efficient, high capacity air filtration. The seat comprises an assembly including upper and lower halves joined along a horizontal seam. The seat halves pivot on an axle and are biased apart to sense use of the device to control its on/off timing. The device is activated as the user sits on the seat and is programmed by a controller to continue for a length of time after toilet use.