California Code, Public Utilities Code - PUC § 561

(a) Every railroad corporation, passenger stage corporation, passenger air carrier, and street railroad corporation providing departures originating in this state shall prohibit the smoking of a tobacco product in the passenger seating area of every passenger car, passenger stage, aircraft, or other vehicle.

(b) Every such corporation and carrier shall display in the passenger seating area of every passenger car, passenger stage, aircraft, or other vehicle, notices sufficient in number, posted in such locations as to be readily seen by boarding passengers, advising passengers of the no smoking requirements pursuant to subdivision (a).  Words on such notices which state “No Smoking” or an equivalent phrase shall be at least three-quarters of one inch high, and any other explanatory words on the notices shall be at least one-quarter of one inch high.

(c) No person shall smoke a tobacco product in a space known by him or her to be designated for nonsmoking passengers.  A violation of this subdivision is not a crime.

(d) As used in this section, “passenger air carrier” shall have the same meaning as provided in Sections 2741 and 2743.

(e) For purposes of this section, “smoke” and “smoking” have the same meaning as in subdivision (c) of Section 22950.5 of the Business and Professions Code.

(f) For purposes of this section, “tobacco product” means a product or device as defined in subdivision (d) of Section 22950.5 of the Business and Professions Code.