Canadian Occupational Safety

July/August 2020

Canadian Occupational Safety (COS) magazine is the premier workplace health and safety publication in Canada. We cover a wide range of topics ranging from office to heavy industry, and from general safety management to specific workplace hazards.

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Page 17 of 31

F E A T U R E 18 The system includes a water-cooled cap and vest and water-cooled undergarments. The personal air-conditioning vest uses a compressor and cooling (vortex) tube. The tube pumps cool, compressed air through a plasticized vest worn by the worker. The cold air circulates around the vest and reduces the temperature around the worker. "It's very popular with welders. We do a lot of work with the ship-building industry. When welders are in the ship's hold, it's quite hot in there," says Marcus Shuter, Vortec product manager at Cincinnati, Ohio-based Vortec (an ITW company), adding that the device saves time because it requires no maintenance. "It cools almost instantaneously. As long as you have it clipped up and the compressed air going through it, it's cooling. So, there's no downtime." In direct sun, wearing a hat prevents overheating. Cooling pads and skull caps can be worn inside a hard hat, and a flexible shade can be attached to a hard hat brim to protect the neck and eyes from the sun. Outdoor workers should wear polarized sunglasses. If possible, choose work gloves made of material that is lightweight, breathable and light coloured. Reflective clothing In some facilities, aluminum coverings are needed to provide protection against excessive radiant heat. These specialized garments, including aprons, jackets, suits and gloves, must cover the worker from neck to feet. Aluminized heat- reflective clothing can reflect up to 95 per cent of radiant heat. Flame-resistant PPE Many standard kinds of PPE are not practical for workers who, due to the presence of electric-arc, flash fire, combustible dust and electrical hazards, also need flame-resistant clothing. For manufacturers, the problem has been to provide a worker with personal clothing or equipment that will cool the worker but, at the same time, not put the worker at increased risk. "That challenge is not easily solved. Unfortunately, if there is a high-energy, thermal event, like an arc flash or a flash fire, cooling PPE like the cold-gel packs can melt and add to the injury. The harness that holds the gel packs is typically not flame resistant, it doesn't have arc rating, so it could transfer injury to the wearer," Sang says. "Things like bandanas [and] cooling cloths are made from microfibre cloth — they're also typically going to melt, drip and add to the injury." However, he adds, there are fabrics that combine FR and moisture-wicking properties. They are used to make FR work garments such as coveralls and shirts. Otherwise, where heat and flame hazards co-exist, employers should try to reduce worker heat exposure through safer work practices and not rely on PPE. Online tools Various organizations have developed calculation tools to help managers and workers reduce or prevent heat stress. For example, the Montreal-based Robert-Sauvé Research Institute for Occupational Health and Safety (IRSST) provides access to three computer-based tools on its website. Two of these tools assist in the calculation of the "alternate work-rest regimen" needed when various hot work conditions apply, says Capucine Ouellet, occupational hygienist at the IRSST. One of them estimates the regimen according to the occupational health and safety regulation of Quebec. The other estimates the work-rest regimen based on the exposure limits recommended by the Cincinnati, Ohio-based American Conference of Governmental Industrial Hygienists (ACGIH), which sets maximum exposure limits for various workplace hazards. Most jurisdictions in Canada follow ACGIH guidelines when setting exposure limits. "It gives you a precise number for rest time. It tells you how many minutes you need to rest per hour of work, considering the level of heat stress. This is a minimum," Ouellet says. The third computer-based tool on the IRSST website calculates the "corrected" air temperature (CAT). Users enter information regarding air temperature, relative humidity, exposure conditions and workload. The tool calculates a "corrected" or actual temperature and indicates the level of heat stress, while recommending preventive measures (including hydration frequency) appropriate for that risk level. In the lower-risk green zones, the recommendations are more about preparing in case the heat stress rises. "That's because heat stress changes every hour. In the morning, you can be in the green zone. In the early afternoon, you can be in the yellow [higher-risk] zone, though still doing the same work — because the temperature rises as the day goes on. That's true for outdoor work and sometimes true also for indoor work, as in kitchens or foundries," Ouellet says. "This CAT tool is very easy, friendly. Everybody can use it in the field. It's good for workers and employers." All companies should begin planning for heat stress before temperatures climb. Many companies, Fernandes says, don't start considering the risk of heat stress until the summer is well underway. "Seasonal organizations are probably on top of it. But newer facilities, it's not really on their radar until it gets hot out," she says. "That's when assessments happen, and they start creating their heat stress program for the next year." "Seasonal organizations are probably on top of [heat stress prevention]. But newer facilities, it's not really on their radar until it gets hot out." Capucine Ouellet, occupational hygienist at the IRSST HIDDEN FACTORS CONTRIBUTING TO HEAT STRESS Source: Autometrix Isolation: working alone or in isolated locations Monitoring & controls: poor monitoring, choosing wrong heat stress indicators to monitor/control Culture: working without breaks, drinking energy drinks and alcohol (which could lead to dehydration) Education: lack of knowledge on signs of heat stress and dehydration or lack of knowledge on how much water to drink to prevent dehydration

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