With the written consent of the property owner, a person may use unvented portable kerosene-fired heaters in single family dwelling units and in commercial establishments in this State if the heaters otherwise comply with the State Fire Prevention Code regulations in effect on January 1, 1982. “Commercial establishment” does not include: Places of public assembly capable of accommodating more than 50 persons; Child care centers; Educational occupancies; Health care occupancies; Hotels and motels; or Buildings (other than office facilities) where open flame devices would readily ignite flammable liquid vapor, explosives, or dust, or buildings over 3 stories in height. In commercial establishments, portable kerosene heaters may not be located in such a manner as to obstruct exits. This section shall not be construed to prohibit or allow the prohibition of the demonstration or repair of unvented portable kerosene–fired heaters in any commercial establishment. The manufacturer shall affix to each portable kerosene heater, in a safe and prominent place, a nondetachable warning label which states: WARNING. This unit must be used in an area which has proper ventilation. Consult owner’s manual for details and instructions. Use of this heater may possibly be dangerous to persons with respiratory or circulatory disorders. Only “water-clear” kerosene meeting 1-K (ASTM) specifications should be used in this heater. In Baltimore City, this section does not affect or supersede any local law or ordinance which is more stringent or imposes a higher standard regarding the use or sale of portable kerosene heaters.