Mass. Gen. Laws ch. 149, § 139

In any mercantile or manufacturing establishment or hotel or railroad where the nature of the work renders it necessary for any or all employees, before beginning work, to make a substantially complete change of clothing, exclusive of underclothing, separate lockers, closets or other receptacles, each with a lock and key, shall be provided for the use of such employees. Whoever violates this section shall be punished by a fine of not less than five nor more than twenty dollars.