Canadian Occupational Safety

16 www.cos-mag.com Canadian Occupational Safety ne weekend in 2017, after freezing rain had left Win- nipeg's sidewalks and roads covered in ice, more than 200 people ended up in emergency departments across the city with slip and fall injuries. The most common injuries were wrist fractures, ankle injuries and hip fractures, while 60 people required emergency surgeries. Serious injuries caused by slips on ice are very common. From 2011- 16, the average annual number of hospitalizations for these slips in Saskatchewan (the highest number among the 10 provinces) was 43.4 per 100,000 residents. Alberta, the next highest, had 42.3 per 100,000 population, followed by New Bruns- wick at 39.3. Despite the frequency and serious- ness of injuries caused by slips on ice, little work had been done to improve the slip-resistance of winter footwear. However, a few years ago, scientists at the Toronto Rehabilitation Insti- tute (TRI), part of the University Health Network, launched a project to test casual and work boots for their ability to stop slips and falls in winter. Since then, the "snowflake" rating system has tested and rated hundreds of winter boots, and has attracted enormous amounts of attention from consumers, manufacturers and employers. "This has been a very intractable problem. Falls just kept increasing, and it looks as though this (proj- ect) is making a big difference," says Geoff Fernie, senior scientist at the TRI and faculty member at the Uni- versity of Toronto. HOW DOES IT WORK? Testing takes place in the Winter- Lab, a specially built laboratory that resembles a huge ice box and sits on a platform that can be tilted to produce different angles. The team of researchers can create different winter conditions in the lab, variously covering the floor with wet ice, dry ice or powdered ice with snow and ice shavings. To test each boot, a vol- unteer, wearing a harness to prevent them from hitting the floor, walks up and down on real ice as an operator gradually increases the angle of the slope until the volunteer slips. Testing is done on dr y, cold ice and on wet ice because, Fernie says, the performance of footwear varies dramatically depending on whether the ice is just beginning to melt, when the sun shines during the day or whether it's really cold and hard. The two kinds of ice require different kinds of footwear. Several volunteers try out each boot. Researchers record the steepest angle at which the volunteer remains upright in each of the different icy con- ditions. That becomes the "best angle" for the performance of the boot. From the various best angles for each boot, the lowest number is selected for the snowflake ratings because, as Fernie says, they want to have the safest results possible. "We express the performance of the shoe in what we call the MA A, the maximum achievable angle. And, because putting a number, an angle, on the screen is hard for consumers to remember, we simply invented a 'snowflake' scale. Just the same as a restaurant has stars, we have snow- flakes," he says. TRI set up a three-snowflake scale, with the minimum at seven degrees: To get one snowflake, a boot must perform on a seven-degree slope consistently, in both wet and dry conditions, going up and down. The seven-degree angle was chosen because it is commonly used in building. It is the angle of wheelchair ramps that lead from the sidewalk to the road, for example. If a boot continues to grip at an angle of 11 degrees or more, it gets two snowflakes; if it grips at 15 degrees or more, it gets three snowflakes. While the concept of the testing may be simple, the results are mean- ingful, Fernie says. In large part, that's because the testing is human-based. Most personal protective equipment (PPE) is tested on machines, but winter boots in the snowflake testing are worn by actual humans. "The previous kind of testing that's used in a limited way is to set up a kind of robotic machine that either drags feet or takes a pace on the ice. It gives you consistent results, but it's not sensitive to changes that you can experience as people walk," he says. "But we found this testing to be reliable and useful in giving you a realistic understanding of how well the boot is performing." Results of the first test were published in November 2016 on RateMyTreads.com. Out of about 100 boots tested, only 10 achieved one snowflake. No make of boot got more than that. RateMyTreads.com is updated reg- ularly. Boots that rate no snowflake, and those that are between one and two snowflakes, are now also listed on the website, along with the angles they achieved. Research at the TRI is supported by grants and by donations to the institute's foundation. They are now charging companies for testing. Two classes of materials have consis- tently scored within the top 10 in the snowflake slip-resistance ratings, says Iain Summers, vice-president of inno- vation and footwear at Calgary-based Mark's. Green Diamond, invented for the tire industry in Iceland, contains fine synthetic quartz or crystals that scratch the surface of the ice. It works best on cold, hard ice and is usually less effective on wet, soft ice. "The secret of Green Diamond is not the crystals or quartz, but the binding agent that they treat those crystals in and that then attaches itself to the rubber, so it's through- out the rubber. As you wear down the rubber, the quartz or crystals fall out, but new ones come to the sur- face because they're mixed through the rubber," Summers says. The second top-scoring mate- rial, Arctic Grip, was developed by Vibram Corporation, based in Albi- zzate, Italy, and works best on wet ice. Arctic Grip has a gritty texture and is essentially fibreglass filings or shavings, which appear as blue flecks, mixed into a synthetic rubber compound. As with Green Diamond, the slip-resistant filler is distributed throughout the entire outsole. "Arctic Grip works better in East- ern Canada than in Western Canada because our climate here (in Calgary) is extremely dry, compared with East- ern Canada," Summers says. The same slip-resistant filler is used in Arctic Grip Pro boots, an industrial safety boot. A fire-retardant version of this boot is manufactured to meet NFPA performance standards and is designed for use by firefight- ers who deal with slippery outdoor conditions in winter, says Bill Ells, Vibram's vice-president of sales, who is based in North Brookfield, Mass. "You get those nights where the ice is melting during the day and freezing during the night," he says. Stepping out of the rig and onto wet ice is the cause of many serious falls for firefighters, so the idea is to mini- mize that, he adds. The publication of the first snow- f lake slip-resistance ratings in November 2016 received a great deal An unusual rating system gives workers a way to select slip-resistant winter boots for the first time By Linda Johnson ON THIN

• Cover