(1) To protect children in the public schools of this state from exposure to the addictive substance of nicotine, each school district board of directors shall have a written policy mandating a prohibition on the use of all tobacco products on public school property. (2) The policy in subsection (1) of this section shall include, but not be limited to, a requirement that students and school personnel be notified of the prohibition, the posting of signs prohibiting the use of tobacco products, sanctions for students and school personnel who violate the policy, and a requirement that school district personnel enforce the prohibition. Enforcement policies adopted in the school board policy shall be in addition to the enforcement provisions in RCW 70.160.070.