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LEGISLATIVE INTERPRETATIONS

OCCUPATIONAL HEALTH AND SAFETY ACT

Confined space – Monitoring

Topic: Confined space – Monitoring Issued By: V.P.,WorkSafe Services
Statute: Regulation 91-191 Date Issued: April 12, 1999
Section: 263(1)(e) Date Revised:

263(1) Where an employee is about to enter into a confined space, an employer shall appoint a competent person to verify by tests that

(a) the concentration of airborne chemical agents or airborne dust in the confined space is not hazardous to the health or safety of the employee,
(b) the concentration of an airborne chemical agent or mixture of chemical agents or airborne dust in the confined space does not exceed 50% of its lower explosive limit,
(c) the level of physical agents in the confined space is not hazardous to the health or safety of the employee,
(d) the percentage of oxygen in the atmosphere in the confined space is not less than 19.5% by volume and not more than 23% by volume,
(e) the concentration, level or percentage referred to in paragraphs (a) to (d) is able to be maintained during the period of proposed occupancy of the confined space by the employee,

Question:
How is the competent person able to verify that the levels in (a) to (d) are able to be maintained unless they have constant monitoring?

Answer:
Constant monitoring is not necessary where there is an established history of the concentration levels being maintained and no change in the equipment or process, and periodic monitoring is done.

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