The director shall make, adopt, modify, and repeal rules and regulations governing safety and health standards for conditions of employment as authorized by this chapter after a public hearing in conformance with the administrative procedure act and the provisions of this chapter. At least thirty days prior to such public hearing, the director shall cause public notice of such hearing to be made in newspapers of general circulation in this state, of the date, time, and place of such public hearing, along with a general description of the subject matter of the proposed rules and information as to where copies of any rules and regulations proposed for adoption may be obtained and with a solicitation for recommendations in writing or suggestions for inclusion or changes in such rules to be submitted not later than five days prior to such public hearing. Any preexisting rules adopted by the department of labor and industries relating to health and safety standards in workplaces subject to the jurisdiction of the department shall remain effective insofar as such rules are not inconsistent with the provisions of this chapter.