Canada Occupational Health and Safety Regulations

11.11 (1) If ventilation equipment is used to maintain the concentration of a chemical agent or combination of chemical agents in a hazardous confined space at or below the concentration referred to in subparagraph 11.05(1)(a)(i), or to maintain the percentage of oxygen in the air of a hazardous confined space within the limits referred to in subparagraph 11.05(1)(a)(iii), the employer must not grant access to the hazardous confined space unless

• (a) the ventilation equipment is

  • (i) equipped with an alarm that will, if the equipment fails, be activated automatically and be audible or visible to every person in the hazardous confined space, or

  • (ii) monitored by an employee who is in constant attendance at the equipment and who is in communication with any person in the hazardous confined space; and

• (b) if the ventilation equipment fails, the person will have enough time to escape from the hazardous confined space before

  • (i) the concentration of the chemical agent or combination of chemical agents in the hazardous confined space exceeds the concentration referred to in subparagraph 11.05(1)(a)(i), or

  • (ii) the percentage of oxygen in the air of the hazardous confined space ceases to remain within the limits referred to in subparagraph 11.05(1)(a)(iii).

(2) If the ventilation equipment fails, the employee referred to in subparagraph (1)(a)(ii) must immediately inform any person in the hazardous confined space of the failure of the equipment.

(3) If the report referred to in subsection 11.03(2) determines that a hazardous confined space requires continuous ventilation, the employer must ensure continuous atmospheric monitoring while the hazardous confined space is occupied.