1. Notwithstanding any provision of this chapter to the contrary, an owner, operator, manager, or other person having custody or control of an area otherwise exempt from the prohibitions of section 142D.3 may declare the entire area as a nonsmoking place.
2. Smoking shall be prohibited in any location of an area declared a nonsmoking place under this section if a sign is posted conforming to the provisions of section 142D.6.