Mo. Rev. Stat. § 292.400
All hoppers or chutes or similar devices used in the course of any process or manufacture referred to in section 292.310 shall be provided with a hood or covering, and an adequate and efficient apparatus or other proper device for the purpose of drawing away from the employees, noxious, poisonous or injurious dusts, and preventing the employees from coming into unnecessary contact therewith; and all conveyances or receptacles used for the transportation about or the storage in any place where any such process or manufacture or labor referred to in section 292.310 is carried on, shall be properly covered or dampened in such a way as to protect the health of the employees, and no refuse of a dangerous character incident to the work or process carried on in any such place shall be allowed to remain accumulated on the floors thereof.
§ 292.400, RSMo