§ 29. Procedure for issuing safety and health rules. Before any rule is adopted, amended or repealed there shall be a public hearing thereon, notice of which shall be published at least once, not less than ten days prior thereto, in such newspaper or newspapers as the commissioner may prescribe. The commissioner may appoint committees composed of employers, employees and experts to suggest rules or changes therein. Every rule adopted and every amendment or repeal thereof shall be promptly published in such newspaper or newspapers as the commissioner may prescribe. The rules and all amendments and repeals thereof shall, unless otherwise prescribed by the commissioner, take effect twenty days after the first publication thereof and certified copies thereof shall be filed in the office of the department of state.