Canadian Occupational Safety

June/July 2015 19 doorways, lighting and ventilation — that indicate they're designed for humans to inhabit for long periods of time. "Something that's not designed for human occupancy does not meet the requirements of the building code," she says. To assess if the space could become hazardous to a worker, consider the atmospheric hazards. The primary atmospheric danger in confi ned spaces is oxygen defi ciency or enrichment, says Wesley Sim, technical safety instructor at Hazmasters in Burnaby, B.C. The permissible oxygen range is 19.5 per cent to 23 per cent. Sim, however, advises his students not to enter a space unless the oxygen level is at 20.9 per cent. Sim says three processes commonly consume oxygen in confi ned spaces: • microbial action caused by organics • hot work (burning processes require oxygen; plus, leakage of shielding gas from a welding hose can displace oxygen) • oxidation, a problem affecting barges and underground pipes and ladders. Another atmospheric hazard is fl am- mable gases, vapours and dusts, Sim says. The concentration of these sub- stances should be kept to less than 10 per cent of their lower explosive limit (LEL). The atmosphere should also be monitored for toxic air contaminants. After assessing for ease of entry, human occupancy and hazards, occupational health and safety profes- sionals should be able to determine if the work space is a confi ned space, in accordance with applicable provincial or federal legislation. DO I NEED A PERMIT? According to CSA Z1006, whether an entry permit is required before a person enters a space is based on a prior identifi cation of the area as a confi ned space and, if it is, on a risk assessment. If certain measures, including atmospheric monitoring, lockout or ventilation, are required for a person to enter the space, then a permit is necessary. When a permit system is in place and followed correctly, people are forced to do a number of things to verify and check off that they have followed proper procedures, says Wayne Donnelly, vice-chair of the CSA Z1006 committee, who is based in Winnipeg. "You ensure the space is safe before you enter and it remains safe the entire time the space is occupied, until the time the person leaves," he says. In addition to serving as a review of the precautions needed for safe entry, entry permits reduce the likelihood of unauthorized workers gaining access to confi ned spaces, Martell says. Using a permit system also creates a written record of the steps taken to comply with the requirements of confi ned spaces regulations. An employer who doesn't use an entry permit to restrict access to confi ned spaces may be guilty of criminal negligence under Bill C-45. This is especially true in jurisdictions where permits are required but is also possible in provinces where the OHS regulations don't mandate the use of entry permits, says Martell. Entry permits aren't specifi cally required by New Brunswick OHS reg- ulations but are recommended and deemed a best practice in industry, he says. In Ontario, an entry permit is required every time a worker enters a confi ned space. A permit is required for each location and a new permit is required for each day (or shift) the work continues. In B.C., permits are required when the space has been assessed as having a high atmospheric hazard; it requires lockout or isolation procedures (where piping that is attached to the confi ned space and contains a hazardous substance must be disconnected, blanked or blinded or locked out); or there is a hazard of entrapment or engulfment. The failure to identify confi ned spaces can take a heavy toll. Accidents in confi ned spaces tend to be serious, often fatal, so it is always better to err on the side of safety, Sim says. "In a confi ned space, the game is different. It's not like working in a shop," he says. "If something goes sideways, you're not getting out of there in a hurry." Linda Johnson is a freelance writer based in Toronto. She can be reached at lindajohnson@sympatico.ca. KNOW THE RISKS While working in a confi ned space, workers may be subject to various hazards and risks, including: CONFINED CONFUSED • work activities • the potential for hazardous atmosphere • conditions that exist prior to entry or develop during entry • physical characteristics (such as confi guration and location of space) • potential for engulfment (being surrounded by a substance that can be inhaled or can exert enough force on the body to cause death by crushing or strangulation) or entrapment by material • potential for fi re or explosion • biological hazards • physical hazards (such as temperature extremes, lighting and vibration) • hazards resulting from change of conditions during occupancy (such as the release of toxic gases). Source: CSA Z1006 AND

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