Missouri Revised Statutes Title XVIII. Labor and Industrial Relations § 292.070. Doors to open outward, not to be bolted, when

In all such establishments the main doors, both inside and outside, shall open outwardly, when the director, in writing, so directs; and no outside or inside door of any building wherein labor is employed shall be so locked, bolted or otherwise fastened during the hours of labor as to prevent egress.