(b) Notwithstanding the provisions of this subdivision or any other general, special or local law to the contrary, and except as provided in the provisions of article thirteen-E of this chapter, a board of health of a county health district, if there be one, shall have sole jurisdiction to enforce the provisions of article thirteen-E of this chapter on a county-wide basis. 2. In a county containing one or more cities having a population of fifty thousand or more, according to the last preceding federal or state census or enumeration which are not to be included in a county or part-county health district, a majority of the supervisors representing that part of the county outside such city or cities may petition the board of supervisors to establish such part of the county as a part-county health district and, upon receiving such petition, the board of supervisors shall forthwith file a certified copy of such petition with the commissioner. 3. Whenever the provisions of this section shall have been proposed to be adopted in any county, and proceedings have been taken to establish a county or part-county health district within any such county, the board of supervisors shall notify the commissioner in writing of the proposed establishment of such county or part-county health district, and in such notice shall state the extent of the territory intended to be included within such district. The consent of the commissioner to the establishment of any such health district shall be evidenced by a certificate, setting forth the approval of the commissioner to the establishment of such health district. Such certificate shall be filed with the clerk of the board of supervisors.