A material not releasing gaseous organic substances during use is used as a filter medium and a sealing material for tightly sealing between the medium and a frame. Specifically, a synthetic paraffin not containing an aliphatic hydrocarbon having not more than 19 carbon atoms or less is used as a non-silicone type water repellent contained in a treatment agent for forming fibers into a cloth-like filter medium. A carboxylic acid ester having 400 or more molecular weight is used as a plasticizer and a phenolic compound having 300 or more molecular weight is used as an antioxidant to be added to the treatment agent and the sealing material. This enables that the gaseous organic substances are not present in a clean room, in a semiconductor production apparatus or in the like. Further, if the filter medium and the sealing material are formed of a material not releasing organic phosphorus compounds and boron compounds in the air, a clean room and a local facility particularly suitable for use in the production of semiconductors are provided.