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6. Hazard Assessment | Confined Spaces Guideline

  • Issued: September 2006
  • Revised: July 2011
  • Content last reviewed: July 2011

Disclaimer: This resource has been prepared to help the workplace parties understand some of their obligations under the Occupational Health and Safety Act (OHSA) and regulations. It is not legal advice. It is not intended to replace the OHSA or the regulations. For further information please see full disclaimer.

Section 6 - Confined Spaces Regulation (O. Reg. 632/05)

  • 6 (1)  Before any worker enters a confined space, the employer shall ensure that an adequate assessment of the hazards related to the confined space has been carried out.
  • (2)  The assessment shall be recorded in writing and shall consider, with respect to each confined space,
    • (a) the hazards that may exist due to the design, construction, location, use or contents of the confined space; and
    • (b)  the hazards that may develop while work is done inside the confined space.
  • (3)  The record of the assessment may be incorporated into an entry permit under section 10.
  • (4)  If two or more confined spaces are of similar construction and present the same hazards, their assessments may be recorded in a single document, but each confined space shall be clearly identified in the assessment.
  • (5)  The employer shall appoint a person with adequate knowledge, training and experience to carry out the assessment and shall maintain a record containing details of the person’s knowledge, training and experience.
  • (6)  The assessment shall contain the name of the person who carries out the assessment.
  • (7)  The person shall sign and date the assessment and provide it to the employer.
  • (8)  On request, the employer shall provide copies of the assessment and of the record mentioned in subsection (5) to,
    • (a) the joint health and safety committee or the project’s health and safety committee, as the case may be, or the health and safety representative, if any; or
    • (b) every worker who performs work to which the assessment relates, if the workplace has no joint health and safety committee or health and safety representative.
  • (9)  The employer shall ensure that the assessment is reviewed as often as is necessary to ensure that the relevant plan remains adequate.

Before any worker enters a confined space, the employer shall ensure that an adequate assessment of the hazards related to the confined space has been carried out.

The hazard assessment is not intended for the purpose of evaluating whether or not a space is a confined space. The assessment is intended to be carried out as part of the entry preparation process. It is critical to identifying the existing hazards of individual confined spaces, and the hazards that may develop during the work activity inside the confined space. In addition to assessing the atmospheric hazards that pose an imminent danger to workers, the employer should also assess other hazards present in the space.

The assessment may include the following hazards:

  • Oxygen deficiency/oxygen enrichment
  • Flammable, combustible or explosive agents
  • Toxic air contaminants, smoke, fumes, and dusts
  • Residual chemicals/materials
  • Ignition hazards, including hot work, tools and other potential sources of ignition
  • Chemical contact hazards, including acids, alkalis
  • Physical hazards, including mechanical hazards, thermal stress, humidity, radiation, noise and vibration, working/walking surfaces, engulfing materials, physical obstacles, poor visibility
  • Electrical hazards, including lines and cables, exposed terminals
  • Traffic hazards, including pedestrian, mobile equipment
  • Biological hazards, including animals and biological agents
  • Other hazards related to the confined space, including piping/distribution systems, pressurizing fluids, any type of uncontrolled energy (water, liquid, vapour, electric, magnetic, gaseous, etc.), limited access and egress

A hazard assessment must be completed by a person with adequate knowledge, training and experience to be able to perform the assessment. This written assessment must be completed, signed, and dated prior to any worker entering a confined space.

The employer must maintain a record containing details of the person’s knowledge, training and experience. The employer must have the assessment reviewed as often as necessary to ensure that the resulting plan remains adequate. A record of the assessment may be incorporated into the entry permit.

Is a hazard assessment required for each confined space entry?

The assessment must be carried out before any worker enters a confined space. The employer is required to ensure that the assessment is reviewed as often as is necessary to ensure that the relevant plan remains adequate. Therefore, an assessment is not needed each time a worker goes in and out of the confined space during the period to which an entry permit applies. However, the assessment should be repeated each time that there is a new entry permit issued for work to be done in a confined space. This is because the employer must ensure that there are no new hazards that have developed since the last time that the assessment was carried out. In addition, a different work activity could result in different hazards.

A confined space entry is described on the entry permit with respect to permit duration, its location and the work to be done during that entry. The entry permit may include provisions for exiting the confined space and then returning back to it. These procedures, which could include atmospheric testing and other re-assessment activities, should be identified on the entry permit.

Where the same space is entered for the same type of work at a time not covered by the entry permit, the previous assessment would be useful as a reference. However, the only way to determine whether the hazards in the confined space are unchanged is to complete an assessment.

Can assessments for different spaces be combined into one document?

Assessments for individual confined spaces would normally be written as separate documents. However, where two or more confined spaces are similar in construction and present the same hazards, the assessment for each specific confined space may be recorded in a single document. The specific confined space or spaces to which each assessment applies must be clearly identified in the assessment.

Can I categorize spaces before an assessment is made?

Each confined space would still require an assessment to confirm its category. Some workplaces have several types of confined spaces and have categorized them to use specific/generic controls in the plan. Each category may have measures and procedures to be followed to adequately protect workers for a confined space entry.

When is a hazard assessment supposed to be completed?

A hazard assessment needs to be completed, signed and dated before a worker enters a confined space.

Would I comply if I hire a consultant with the adequate knowledge, training and experience to conduct the assessment?

Yes. An employer may set out in the program that the method for assessing the hazards to which workers may be exposed will be conducted by a consultant with the adequate knowledge, training and experience. The employer would be responsible for familiarizing the consultant with the process and the work to be performed. In those instances where the employer had put a program in place and where that same employer would have called for a consultant to conduct the assessment, it is the responsibility of the employer to give to that consultant a copy of the confined space program.

What should be considered in the assessment of potential atmospheric hazards?

Identification of the potential atmospheric hazards should be done taking into consideration the previous contents of the space, the activities or work tasks within the space that could generate or stir up air contaminants and the potential for the sudden release of air contaminants from sources in proximity to the space.

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Disclaimer: This web resource has been prepared to assist the workplace parties in understanding some of their obligations under the Occupational Health and Safety Act (OHSA) and the regulations. It is not intended to replace the OHSA or the regulations and reference should always be made to the official version of the legislation.

It is the responsibility of the workplace parties to ensure compliance with the legislation. This web resource does not constitute legal advice. If you require assistance with respect to the interpretation of the legislation and its potential application in specific circumstances, please contact your legal counsel.

While this web resource will also be available to Ministry of Labour inspectors, they will apply and enforce the OHSA and its regulations based on the facts as they may find them in the workplace. This web resource does not affect their enforcement discretion in any way.