A seat for a lavatory pan, which includes within its thickness at least one cavity for a deodorizing filter and at least one cavity in the seat or the filter for an electrically powered fan. Air inlet openings are provided in the seat through which air can pass into the filter cavity. The openings are situated around the inside edge of the opening in the seat or in a region of the underside of the seat which does not make sealing contact with the rim of the pan when the seat is lowered and in use and is subject to the weight of a person seated thereon. An air outlet by which odor-free air can exit after being drawn through the filter by operation of the fan, is situated in the rear edge of the seat.