(b) The posting requirements set forth in subsection (a) above do not apply to any vehicle operated in interstate commerce, nor to any chartered vehicle: Provided, That if any vehicle operated in interstate commerce or chartered vehicle has a posted nonsmoking area, no person shall smoke or carry a lighted pipe, cigar, or cigarette in the posted nonsmoking area of such vehicle.
(c) Any person who violates any provision of this section is guilty of a misdemeanor, and, upon conviction thereof, shall be fined not less than twenty nor more than one hundred dollars.