If a mechanical exhaust system is required, the outside air needed to replace the air exhausted from each room shall be obtained from ventilation openings in that room or from a mechanical ventilating supply system installed for that room.
Exceptions:
1. In foyers, living quarters, offices, rest rooms, lobbies, locker rooms, medicine rooms and picture galleries, ventilation also may be obtained from a mechanical ventilating supply system serving rooms adjacent to the designated room, either alone or in combination with the designated room, if the quantity of air supplied to the adjacent room is not less than that required for both the designated room and the adjacent rooms.
2. In public kitchens and serving pantries, ventilation air may be obtained through ventilation openings from dining rooms adjacent to designated rooms, if the area of the ventilation openings in the dining room is not less than 4 percent of the combined floor area of the dining room and the kitchen or serving pantry. Such ventilation comply with the following:
2.1 If the dining room is provided with a mechanical supply system of ventilation, air from the dining room can be taken through proper openings into the kitchen and exhausted from the kitchen. Such air shall be considered as exhaust from the dining room and as supply air into the kitchen.
2.2 A kitchen exhaust system need not be increased beyond the requirements for kitchen exhaust as indicated in Table 18-28-403.3.
2.3 If the amount of air exhausted from the dining room through the kitchen is not sufficient to provide exhaust as indicated in Table 18-28-403.3, additional exhaust shall be taken from the dining room area to make up such requirement, either by increasing exhaust from the kitchen or by installing a separate additional mechanical exhaust system.
3. In bath, toilet, and urinal rooms, check rooms, storage room, storage battery rooms, telephone switch rooms, and other rooms of similar character, ventilation may be obtained from ventilation openings in these rooms or from openings to uncontaminated rooms adjacent to the designated rooms if the following requirement is met:
3.1 The quantity of air supplied to the adjacent rooms is not less than the air exhausted through the designated rooms.