23.—(1) Suitable and sufficient steps shall be taken to ensure, so far as is reasonably practicable, that every workplace or approach thereto has sufficient fresh or purified air to ensure that the place or approach is safe and without risks to health.
(2) Any plant used for the purpose of complying with paragraph (1) shall, where necessary for reasons of health or safety, include an effective device to give visible or audible warning of any failure of the plant.