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 16 of 31 17 very effective at wicking moisture away from the skin. A material commonly used for cooling work wear is PVA — polyvinyl acetate. PVA is extremely absorbent and can hold water for a long time. It is used to make cooling vests and cooling towels, which are worn around the neck. The user saturates the garment in water for one to two minutes, and then wrings it out before putting it on. The material is dry to the touch. Microfibre fabrics, used to make towels, cooling neck bands and bandanas, also retain water much more effectively than regular towel material. Moreover, microfibre is soft so it's easy to wear against the skin for long periods of time. However, cooling doesn't last as long as with PVA. Microfibre towels are activated, like PVA, by being soaked in water. Some manufacturers have started to combine PVA and microfibre or cotton to get both the long-lasting cooling properties of PVA and the softness of microfibre. These hybrid should cover as much skin as possible, wearing long sleeves and pants. Choose clothing that is lightweight, loose fitting and comfortable. "The air gaps help insulate you against the heat. Also wear light- coloured clothing. Dark colours absorb heat, so wear khaki, light blue or florescent yellow," says Derek Sang, technical training manager at Nashville, Tenn.-based Bulwark Protection. Wicking While cotton is a breathable fabric, it also absorbs moisture well and can become uncomfortable. "Once it reaches saturation, cotton stays wet. So, workers have to deal with the discomfort of dragging this wet fabric around with them during their workday," he says. Instead of using cotton, therefore, many cooling garments are made of "wicking" fabrics. These materials pull moisture away from the body and push it toward the surface of the fabric, where it can evaporate, thus helping to keep skin dry. "If I'm dry, I'm going to feel cooler. If I can move the moisture from my body as it sweats quickly out into the environment, I'm going to feel cooler throughout my workday," he says. Wicking fabrics are used to make garments ranging from underwear and socks to shirts and coveralls. Many wicking fabrics are made of high-tech polyester. Among other effective moisture-wicking fabrics are polypropylene, merino wool, wool, nylon and micromodal. Rayon and linen are breathable fabrics but not "If I'm dry, I'm going to feel cooler. If I can move the moisture from my body as it sweats quickly out into the environment, I'm going to feel cooler throughout my workday." Derek Sang, technical training manager at Bulwark Protection materials are used to make such garments as neck coolers, bandanas and headbands. Temperature-controlled clothing Water, air and ice are used to keep the wearer's body temperature down. With one kind of vest, the user fills the garment with water, which stays in the vest for a few days. A vest may also be equipped to hold cooling packs made of ice or frozen phase-change material (a substance that changes form, usually between solid and liquid). The packs maintain a constant, comfortable temperature for several hours. They may be held in the vest by tape, integrated into the vest or placed in the vest pockets. Some systems use an external device to drive cooling liquid or air through workers' garments. Because workers are attached to an external, stationary device, their range of movement is limited. With water-cooled garments, an external pump pushes a liquid through tubing that is sewn into the garment. MAIN HEAT STRESS INJURIES AND SYMPTOMS Heat rash red raised rash; impairs sweating and decreases effectiveness of sweating Source: Health Safety & Environment Encyclopedia Heat cramps muscle cramps; pain or spasms in abdomen and/or legs Heat exhaustion moist, clammy skin; dilated pupils; normal or subnormal temperature; dizziness, confusion and/or nausea; weak pulse; rapid breathing Heat stroke dry, red, hot skin; pupils constricted; very high body temperature; dizziness, confusion and/or nausea; rapid pulse; unconsciousness; coma; death

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