(a) A person who smokes a pipe, cigar or cigarette in a mill, factory, barn, stable or other outbuilding belonging to or occupied by another person, or in a public building in which a notice containing this section, prohibiting such smoking, signed by the owner, agent, occupant or custodian of the same is posted conspicuously near the main entrance thereof, shall be fined not more than $5.00.

(b) All prosecutions under this section shall be commenced within thirty days from the date of the offense.