No trapped plumbing fixture shall be located in any room or apartment which does not contain a window placed in an external wall of the building or is not provided with a system of ventilation.
Every toilet room and every water closet or urinal compartment, unless provided with a suitable system of exhaust ventilation, shall be ventilated directly to the outer air by movable windows or by skylights with fixed or pivoted louvers. Every such toilet room or compartment shall have a window or glass skylight not less than one foot wide and an area of not less than six square feet for one water closet or urinal, and the area of the window or skylight shall be increased by at least one square foot for every additional water closet or urinal.
If a mechanical system of ventilation is used, such system shall consist of metal or smooth masonry ducts extending from the individual toilet rooms or compartments to a fan or fans of sufficient capacity to exhaust a volume of not less than 30 cubic feet of air per minute for each water closet or urinal, and in no case shall fewer than six changes of air in the toilet room or compartment be allowed per hour. The exhaust ducts shall discharge into the outside air above the room and in such a manner as not to create objectionable odors or a nuisance on the premises or adjacent premises.
Ventilation from toilet room shall be separate and distinct and have no connection whatever with the other ventilating ducts in the building.