All persons, companies or corporations operating any factory or workshop where grinding wheels, or grinding machines, emery wheels or emery belts of any description are used, whether solid emery, leather covered, felt, canvas, linen, paper, cotton or wheels or belts rolled or coated with emery or carborundum or cotton wheels used as buffs, shall, when deemed necessary by the Department of Labor, provide such wheels or belts with blowers or similar apparatus, which shall be placed over, beside or under such wheels or belts in such manner as to protect the person or persons using the same from particles of dust produced and caused thereby, and to carry away the dust arising from or thrown off by such wheels or belts while in operation, directly to the outside of the building or to some receptacle placed so as to receive and confine such dust; Provided, grinding machines upon which water is used at the point of grinding contact and other wheels used for tool grinding shall be exempt from the provisions of this section.