An air pollution control authority may be deactivated prior to the term provided in the original or subsequent agreement by the county or counties comprising such authority upon the adoption by the board, following a hearing held upon ten days notice, to said counties, of a resolution for dissolution or deactivation and upon the approval by the legislative authority of each county comprising the authority. In such event, the board shall proceed to wind up the affairs of the authority and pay all indebtedness thereof. Any surplus of funds shall be paid over to the counties comprising the authority in proportion to their last contribution. Upon the completion of the process of closing the affairs of the authority, the board shall by resolution entered in its minutes declare the authority deactivated and a certified copy of such resolution shall be filed with the secretary of state and the authority shall be deemed inactive.