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# Selecting slip resistant winter footwear for personal support workers

### BACKGROUND:

Falls are among the leading causes of occupational injuries for workers exposed to outdoor winter conditions such as Personal Support Workers (PSWs). Slip resistant footwear is known to reduce the risk of falls, however, it is difficult to predict how well a particular boot will perform prior to purchasing them. Our recently developed Maximum Achievable Angle (MAA) test can be used to rate footwear objectively to address this gap.

### OBJECTIVE:

To rate the slip resistance of a selection of winter footwear that meets the needs and preferences of PSWs.

### METHODS:

We selected 40 representative types of footwear based on survey results from 677 PSWs and applied our MAA test to rate slip resistance.

### RESULTS:

Comfort and slip resistance were rated the most important features for selecting winter footwear. Of the 40 types of footwear tested, six were found to have a good slip resistance on ice.

### CONCLUSION:

The vast majority of winter footwear that meet the needs and preferences of PSWs, perform poorly on ice. Therefore, PSWs should consult our website (ratemytreads.com) for selecting appropriate footwear that will keep them safe in the winter.

## 1Introduction

Falls are among the leading causes of occupational injuries for workers exposed to outdoor winter conditions [1]. These incidents are a major concern for both outdoor workers and their employers as they often result in reduced productivity, expensive compensation claims, lost workdays, not to mention the pain and suffering experienced by the workers themselves. Falls resulted in 36 days of lost time per claim and accounted for one in five of all lost time injuries in Ontario in 2012 [1]. The WSIB estimates the average cost of a fall-related injury was nearly $12,000 and the total financial burden associated with fall-related injuries was$59,000 per injury once staff replacement and lost productivity was factored in [2].

Efforts have been made to minimize the risk of slip incidents by developing new approaches to test indoor walkway/flooring slip resistance [3, 4], but this focus has been lacking for outdoor walkways in the winter. Ice-covered walkways and stairs increase the risk of falls for workers in the winter [5, 6] because of reduced friction on ice-covered surfaces. Polar water molecules have dangling surface hydrogen bonds that result in structural disorder. This structure results in the formation of a quasi-liquid layer at the ice surface that reduces friction [7]. One study at a helicopter manufacturing plant identified that icy surfaces were responsible for 30 out of the 52 reported falls [8]. In particular, the risk of injury is greatest for older workers (over 45). These workers are more likely to experience falls and the resulting injuries led to more time away from work than for younger workers [9].

Slip resistant footwear plays an important role in the prevention of slips-related falls by providing traction that can prevent the loss of balance. A study in restaurant workers found that slip resistant footwear was associated with a 54% reduction in the rate of slipping [10]. Other studies have shown that the use of slip resistant footwear may be even more important for reducing falls than having a strong safety culture in an organization [11, 12]. It is important to note that indoor workers have access to slip resistance ratings to guide their footwear selections [13]. In contrast, outdoor workers exposed to winter conditions have not had access to slip resistance ratings; as a result, they continue to experience high rates of fall-related injuries [14]. A study of 1734 postal worker falls occurring over a 2-year period in the UK found that the most common cause of falls were icy conditions with the majority of falls happening between November and February. This study also found the slip-related falls tended to cluster on days following precipitation when snow and ice were present [14].

Community-based Personal Support Workers (PSWs; also called home support workers, personal aides, or personal care attendants) provide 70% of the publicly-funded home care services in Ontario [15], and they are among the most frequently injured workers in Ontario [16]. While this group most commonly reports overexertion injuries of the back and shoulders, a less commonly discussed major cause of injury to PSWs are slip-related falls that are the result of slippery winter weather. Typically, the clients these workers travel to serve have disabilities that make it difficult to keep their walkways clear of ice. For instance, the winter of 2013/2014 in southern Ontario was particularly harsh and saw several ice storms throughout the season [17]. Many older adults felt trapped in their homes, which made it even more important for PSWs to not miss their client visits. Many of these workers were seriously injured as a result of the slippery conditions. We believe many of these types of injuries could be prevented each year if workers had access to objective winter footwear slip resistance ratings. The effects on workers’ lives, the time lost, and the costs due to injury and recovery are strong motivations for empowering this worker group with information on how to select the best winter footwear.

Until recently, there was no objective information available to consumers to help them select footwear for use in icy weather. Past evaluations of winter footwear have utilized subjective ratings of perceived slipperiness, that involve ranking different types of footwear after use on outdoor winter surfaces [18, 19]. A number of objective measurements have also been attempted on winter surfaces with mechanical devices such as a stationary step simulator [20]. However, these mechanical methods cannot adequately represent the wide variability that constitutes human gait.

To address these drawbacks, our team has developed a new method for testing slip resistance of winter footwear by having participants walk on progressively steeper ice-covered slopes (from 0–20° inclines). This method, namely, the Maximum Achievable Angle (MAA) test, provides a footwear slip resistance rating based on the steepest ice-covered incline that participants can walk up and down without slipping. A model’s MAA score is calculated by finding the minimum angle that all participants were able to ascend and descend across two ice conditions (bare ice and melting ice) without slipping. We recommend users select footwear that achieves a rating greater than 7°. This threshold was chosen based on the maximum slope recommendations for curb ramps in Ontario’s accessibility guidelines [21]. Our MAA testing results are freely available at our website: ratemytreads.com.

#### 3.1.3Safety training and fall-related injury history

Most PSWs were confident or strongly confident in their ability to manage slip-and-fall incidents (67%), yet 72% wanted continuing education on safety tips for winter fall prevention strategies. About 76% of PSWs reported participating in safety training activities and 84% regularly read bulletins regarding slip and fall hazards. Of those who participated in the safety training activities, 82% agreed or strongly agreed that these sessions decreased their risk of falling. PSWs felt holding handrails and wearing good footwear were the most effective ways to prevent falls when providing care in the community (reported by 86% of PSWs for both). Watching out for irregular stairs, water and spills (77.1%), adjusting their stride to a pace suitable for the walking surface (72.0%), spreading salt or sand before starting to walk on the slippery surface (51.0%) were listed as the other common safety precautions used by this worker group. Figure 4 shows the respondent’s attitude to the contributing factors to slip-and-fall incidents. The majority of PSWs listed weather-related conditions like snow and ice as well as the use of inappropriate footwear as the two most important contributing factors leading to slip-and-fall incidents with average weighted scores of 4.66 and 4.33, respectively out of a possible 5 (p < 0.0001).

##### Fig.4

Percentage of participants who ranked contributing factors to slips-and-falls incidents based on their level of importance (rounded to the nearest percent). 0 = Not at all important to 5 = very important. Symbols (-,*) represent 2% and 3%, respectively.

With respect to fall-related injury history, 32% of PSWs reported having fallen in the past 2 years. Of those who have slipped or fallen, 84% occurred outdoor on ice- (62%) or snow-covered (36%) surfaces. Fifteen percent of PSWs reported feeling their footwear was an extremely important factor for fall risk, though almost 28% felt that they were not important at all. Twelve percent of PSWs experienced fall-related injuries in the past two years, with the majority of injuries involving their lower back (35.3%), lower leg/ankle/foot (23.2%) and thigh/knee (15.9%). These fall-related injuries commonly resulted in a Workplace Safety and Insurance Board (WSIB) report (38.1%), modified-work (35.7%) or lost time (32.1%).

#### 3.1.4Winter footwear selection

Table 3 shows a representative list of 40 footwear models that were selected based on our survey results that we felt would meet the needs of our respondents. Even though only 7% of our survey respondents were male, we chose to select five pairs (12.5%) of men’s footwear and the remaining 35 pairs of women’s footwear to ensure a reasonable variety of men’s models were included. Three main factors were considered to select this representative list including price range, popular brands and styles. With respect to the price range, we select 20 models that were priced below $100 (listed by 57%), 14 models priced between$100– $150 (listed by 30%), five models priced between$150– $200 (listed by 9%) and one model priced between$200– $300 (listed by 3%). The list contained models that were more affordable from Payless or Walmart, which were priced in the$50 range, as 20% of our survey respondents select these stores for winter footwear purchases. With respect to the footwear style, the list contained 31 winter boots (76%), seven running shoes (17%) as well as two pairs of casual footwear (2%). We choose the footwear from a variety of brands and stores based on PSWs preference, with more pairs being included from the most popular brands/stores. These include Skechers (five pairs), SoftMoc (four pairs), The North Face (four pairs), Columbia (four pairs), Nike (two pairs) and Payless (two pairs). Some brands were found to be more popular, such as Columbia and Sketchers, compared to the others; however, we were restricted to the number of pairs we selected in those brands because of the other limiting factors, such as preferred price range and available styles.

##### Table 3

The 40 footwear models that were selected for MAA testing based on our survey results. The footwear was categorized as either a winter boots (W), running shoes (R), or casual footwear (C)

 ID Brand Model Style Price 1 Wind river Women’s “Venice” Rain Boot W < $100 2 Payless Women’s Torrent Weather Boot W 3 Weather Spirits Women’s Weather Spirits Boots W 4 Denver Hayes Women’s Laurie Lace-Up Combat Boot W 5 Payless Women’s Whiteout Cuff Down Boot W 6 Skechers Women’s Relaxed Fit: Breathe Easy - Big Bucks R 7 Skechers Women’s Modern Comfort Lace-Up Shoes R 8 Denver Hayes Women’s Sally Lace-Up Shoe R 9 Skechers Women’s Modern Comfort Lace-Up Chukka Boots W 10 SoftMoc Women’s SMOCS 5 Black Chelsea Suede Boots W 11 Cros Women’s Lodgepoint Lace Black Winter Boots W 12 Skechers Women’s GOwalk Move Charcoal Chugga Bootie W 13 WindRiver Women’s Cascade Hiking Shoe R 14 Timberland Women’s Authentics Teddy Fleece Casual Boots W 15 SoftMoc Women’s SALENA 2 Brown Waterproof Ankle Boots W 16 SoftMoc Women’s KIARA Black Lace Up Casual Boots W 17 SoftMoc Women’s MAKALA 2 Chestnut Lined Casual Boots W 18 Skechers Women’s ON-THE-GO 400 Taupe Pull On Suede Boots W 19 Nike Men’s Nike Son of Force Mid-Winter Shoes C 20 Reebok Men’s Reebok Royal Reamaze 2 M W 21 Clarks Women’s Sillian Ankle Boot W$100– $150 22 Sorel Women’s Cumberland Winter Boot W 23 Clarks Women’s Clarks Desert Casual Boots W 24 The North Face Women’s Thermoball Microbaffle Bootie W 25 Columbia Women’s Grand Canyon Hiking Shoe R 26 Timberland Women’s Savin Hill Chelsea Boot W 27 Columbia Women’s Loveland Shorty OmniHeat Black Boots W 28 Sorel Women’s Sorel Plus Out N About Leather Boots W 29 Columbia Women’s Minx Shorty Omni-Heat Boot W 30 The North Face Women’s Ballard Roll-Down Special Edition Boots W 31 Denver Hayes Women’s “Brianna” Low-Cut Lace-Up Ankle Boot W 32 Adidas Women’S Climawarm CP Choleah Padded Boots W 33 Columbia Men’s Redmond Waterproof MidHiking Shoe R 34 The North Face Men’s Back-To-Berkeley Redux Chukka Boots W 35 Nike Women’s Roshe Two High W$150– $200 36 Merrell Women’s Aurora 6 Ice+Waterproof W 37 Merrell Women’s Moab FST Ice+Thermo W 38 Saucony Men’s Saucony PEREGRINE ICE+ R 39 Hush Puppies Women’s Pender Spy Ice+Black WP Leather C 40 UGG Women’s Adirondack Boot II - Leather W >$200

### 3.2Maximum achievable angle test results

MAA scores for all tested footwear are shown in Table 4. Of the 40 types of footwear that were tested, the best performing footwear achieved an MAA score of 14° for melting ice and 10° for bare ice. Six types of footwear passed our threshold value of 7°. The remaining 34 types of footwear fell below our threshold, thus are not recommended for use outdoors in winter (Fig. 5). It is important to note that footwear performance may change between the same models from one year to the next if the manufacturing process is altered. Therefore, we recommend checking www.ratemytreads.com for the most up-to-date information.

##### Fig.5

MAA scores for footwear tested in this study. The footwear models that passed our threshold score of 7° (demonstrating good slip resistance) are indicated with a green circle. The blue bars represent footwear that were tested by four participants in total. The red bars and red squares represent the footwear that completed the screening phase only. The dashed red bars represent the footwear that completed the screening phase successfully but received a failing score (below 7°) with a subsequent participant. The lowest score of the four conditions measured (bare ice uphill, bare ice downhill, melting ice uphill, melting ice downhill) is shown.

##### Table 4

MAA scores for the best performing footwear in our study. This score represents the incline of the steepest ice-covered slope that participants were able to walk up and down without slipping. A footwear model’s MAA score is determined by taking the minimum angle that all participants were able to ascend and descend across both ice conditions without slipping

 Bare Ice Melting Ice ID Uphill MAA Downhill MAA Uphill MAA Downhill MAA 10 9 8 8 7 15 8 7 8 7 36 10 10 11 10 37 9 9 12 11 38 9 7 14 14 39 8 7 11 9

A larger MAA indicates that the footwear is safer on all surfaces. A user wearing footwear with a high MAA score will have better traction on ice on a level or sloped surface in the built environment. In particular, it is important to note that the effective slope in a particular spot can be considerably higher than the underlying built environment surface because of snow and/or ice buildup, as shown in Fig. 6.

##### Fig.6

Snow/ice buildup can increase the effective slope of the built environment.

Of the six types of footwear that passed our threshold, four included a new outsole material technology which allows for better traction. These four types of footwear had Vibram Arctic Grip outsoles, which included microscopic fibers embedded in the rubber outsole. The Arctic Grip technology was included in the women’s Merrell Aurora 6 Ice+Waterproof boots, Merrell - Moab FST Ice+Thermo, Men’s Hush Puppies - Pender Spy Ice+Black WP Leather and Men’s Saucony PEREGRINE ICE+. Of the six models of footwear that passed our MAA threshold, two fell within the $50 to$100 price range defined to be acceptable by 58% of PSWs. The other four types of footwear with best MAA score are within the price range of $150–$200, which only 9% of PSWs found acceptable.

It may be worth noting that our team is in process of developing new composite materials for affordable slip-resistant footwear [25–27] to address the lack of affordable slip resistant footwear. Our initial testing demonstrated that our novel material performed better at maintaining slip resistance on ice after being exposed to simulated wear compared to existing composite outsoles [25, 26]. Aside from its improved wear resistance, the lab-based tests have indicated the coefficient of friction (COF) on ice may be greater than the best footwear on the market [27].

Therefore, future work should include ways of addressing the price gap between PSWs’ willingness to pay and the retail cost of better-performing footwear. For instance, PSWs could be encouraged to purchase slip resistant footwear through the means of bulk buying, discounts, or subsidies from employers etc. An alternative strategy is to motivate the footwear industry to develop different types of footwear, including slip resistant overshoes, which could likely be sold at lower cost. This option may be particularly attractive for PSWs since they currently carry an extra pair of indoor footwear that they change into when they arrive at their clients’ homes. An overshoe that can be removed upon arrival at the client’s home would allow them to travel more efficiently.

Our findings showed that 5% of PSWs (around 34 people in our survey) experienced fall-related injuries (WSIB reported) in the past two years, costing as much as \$59,000 per injury [2]. Therefore, future work should include field tests of slip resistant footwear to calculate the potential economic benefits to employers.

### 3.3Limitations of this study

There are three limitations to this study:

• 1. We select test footwear based on our survey results and availability but we were unable to confirm that these particular footwear models would actually be purchased by PSWs.

• 2. We have on-going work evaluating the wear resistance of the recommended footwear in this study that shows the slip resistance of some of the best performing footwear decreases over as little as 100,000 steps. Future studies will evaluate how often the best performing footwear needs to be replaced due to wear. Results from this future work will be added to the information presented on ratemytreads.com.

• 3. The MAA testing protocol described in this paper has an accuracy of±1° standard deviation (SD) at 95% CI. For the four pairs of recommended footwear with MAA score at the threshold value of 7°, further testing with more participants may result in MAA values that fall below our cut-off. The MAA testing protocol is under on-going review with our growing pool of test data. As a result of this work, we are considering revising the protocol to include testing with larger numbers of participants when approaching the threshold value of 7° to reduce variability near the cut-off value.

For the reasons outlined above in points 2 and 3, we recommend readers consult our ratemytreads.com website for the most up-to-date information before making a footwear purchase.

## 4Conclusions

The majority of winter footwear that would be considered appropriate for PSWs had poor slip resistance on icy surfaces. Only six of the 40 models tested achieved a rating higher than our 7° cut-off. Personal support workers should consider selecting from our recommended footwear list at ratemytreads.com for use in the winter. Our results suggest that there is an opportunity for footwear manufacturers to develop a wider selection of boots with good slip resistance performance since there are only small number that meet the needs and preferences of PSWs.

## Conflicts of interest

All authors declare no conflict of interests with footwear manufacturers/retailers in the current work. Our team does enter into fee-for-service contracts with footwear manufacturers and retailers for slip resistance testing. However, all of the footwear reported in this study was purchased and the testing was funded by the agencies listed in the acknowledgements section.

## Acknowledgments

The authors acknowledge the financial support from the Ministry of Labour (Ontario), Canadian Frailty Network and Saint Elizabeth Health Care.

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