(1) Supply, return and exhaust air openings located less than 2 000 mm above the floor in rooms or spaces in buildings shall be protected by grilles having openings of a size that will not allow the passage of a 15 mm diameter sphere.
(2) Outdoor air intakes and exhaust outlets on the exterior of buildings shall be designed or located so that the air entering the building system will not contain more contaminants than the normal exterior air of the locality in which the building is situated.
(3) Exterior openings for outdoor air intakes and exhaust outlets shall be shielded from the entry of snow and rain and shall be fitted with corrosion-resistant screens of mesh having openings not larger than 15 mm, except where experience has shown that climatic conditions require larger openings to avoid icing over of the screen openings.
(4) Screens required in Sentence (3) shall be accessible for maintenance.
(5) Combustible grilles, diffusers and other devices for supply, return and exhaust air openings in rooms shall conform to the flame-spread rating and smoke developed classification requirements for the interior finish of the surface on which they are installed.
(6) Outdoor air intakes shall be located so that they are separated a minimum distance from sources of contaminants in accordance with Table 6.2.3.12.