S-2.1, r. 4 - Safety Code for the construction industry
3.21.6. Emergency: Where the environment is unhealthy and the situation endangers the life or safety of a person, the employer:
(a) must ensure that the emergency measures prescribed in section 3.21.1 are taken; and
(b) may, despite section 3.21.2, allow a workman to enter the confined space if such workman has had special training for such circumstances and if he is informed of the hazards he will be exposed to.