Each passenger lift-car shall be provided with permanently open ventilation-openings equivalent in area to at least 4 per centum of the area of the car-floor, and at least half of this area shall be either in, or not more than 150 millimeters below, the car-roof:

Provided that, where air is extracted by mechanical ventilation from the car, the area of permanently open ventilation-openings need be equivalent to only 2 per centum of the area of the car-floor.

FIGURE 1
NATURALLY VENTILATED ROOMS

FIGURE 2
MECHANICALLY VENTILATED ROOMS