A. The following are exempt from the requirements of the Night Sky Protection Act: (1) outdoor lighting fixtures on advertisement signs on interstates and federal primary highways;
(2) outdoor lighting fixtures existing and legally installed prior to the effective date of the Night Sky Protection Act; however, when existing lighting fixtures become unrepairable, their replacements are subject to all the provisions of the Night Sky Protection Act;
(3) navigational lighting systems at airports and other lighting necessary for aircraft safety; and
(4) outdoor lighting fixtures that are necessary for worker safety at farms, ranches, dairies, feedlots or industrial, mining or oil and gas facilities.
B. The provisions of the Night Sky Protection Act are cumulative and supplemental and shall not apply within any county or municipality that, by ordinance or resolution, has adopted provisions restricting light pollution that are equal to or more stringent than the provisions of the Night Sky Protection Act.