Missouri Revised Statutes Title XII. Public Health and Welfare § 191.775. Public schools and school buses--smoking, or tobacco or vapor product use prohibited--permissible use of tobacco, where

No person shall smoke or otherwise use tobacco, tobacco products, or vapor products, as such term is defined in section 407.925, in any indoor area of a public elementary or secondary school building or educational facility, excluding institutions of higher education, or on buses used solely to transport students to or from school or to transport students to or from any place for educational purposes. Any school board of any school district may set policy on the permissible uses of tobacco products or vapor products in any other nonclassroom or nonstudent occupant facility, and on the school grounds or outdoor facility areas as the school board deems proper.