Abstract: A nasal filter has a filter layer of very fine monolayer metallic mesh supported on either side by a support layer of coarser metallic mesh, the layers being shaped to cover the lower or nostril portion of the nose. A relatively narrow band of flexible sheet material impervious to the passage of air therethrough is bonded to the filter layer and support layer, the band having one surface bearing removable adhesive material for securing the filter to the nostrils and areas therearound. The nasal filter may have secured thereto a facial mask portion for night wear, the mask portion comprising a principal portion of flexible material impervious to the passage of air therethrough and having a window portion of a filter layer and one or more support layers secured therein. The borders of the mask portion have an inner layer of adhesive material for attaching the mask portion to the upper lip, jaws and throat of the wearer and the window portion is adapted to be worn over or adjacent to the mouth of the wearer.