3.2.8.5.

(1) Except as provided in Sentence (2), where an elevator shaft opens into an interconnected floor space and into storeys that are above such space and that have floor levels more than 18 m above grade, either the elevator doors opening into the interconnected floor space or the elevator doors opening into the storeys above the interconnected floor space shall be protected by vestibules that,

(a) are designed to restrict the passage of contaminated air to the limit described in Sentence 3.2.8.4.(1), and

(b) conform to the requirements of Sentence 3.2.8.4.(3).

(2) Where elevator doors opening into an interconnected floor space are protected by vestibules in conformance with Sentence (1), the elevator doors opening into the lowest storey of the interconnected floor space need not be protected by such vestibules.