(a) Every authority operating any vehicle accessible to the public, designed for the ground transportation of eight or more persons, shall post "No Smoking" signs conspicuously at the entrance to, and on the inside of, each such vehicle. No person shall smoke or carry a lighted pipe, cigar or cigarette in any such vehicle wherein a sign prohibiting smoking is posted.
(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 $20 nor more than $100.