Except as provided in § 15.2-2825, proprietors or persons who manage or otherwise control any building, structure, space, place, or area governed by this chapter in which smoking is not otherwise prohibited may designate rooms or areas in which smoking is permitted as follows:
1. Designated smoking areas shall not encompass so much of the building, structure, space, place, or area open to the general public that reasonable no-smoking areas, considering the nature of the use and the size of the building, are not provided;
2. Designated smoking areas shall be separate to the extent reasonably practicable from those rooms or areas entered by the general public in the normal use of the particular business or institution; and
3. In designated smoking areas, ventilation systems and existing physical barriers shall be used when reasonably practicable to minimize the permeation of smoke into no-smoking areas. However, this chapter shall not be construed as requiring physical modifications or alterations to any structure.