Page 48 - OHS, January/February 2021

PPE: FOOT PROTECTION
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Hectic restaurant kitchens, busy hospital hallways, the de- bris-strewn floors of food manufacturing plants—all are undeniably hazardous work environments that multiply the chance of slip and fall accidents and injuries.
Slip-resistant footwear can help protect workers, but how is slip resistance properly evaluated?
Slip-resistant footwear has been proven to reduce slip and fall occurrence, most recently in a NIOSH study published in the Scan- dinavian Journal of Work, Environment & Health, but all slip-resis- tant shoes are not created equal.1 Even now, there is no standard definition of the term. What does it really mean when a shoe is labelled non-slip, anti-slip or slip resistant?
There are agreed-upon standards and best practices overseeing industrial safety toe footwear. However, and importantly, there is no consensus on an approved and enforced standard of slip-resis- tant protection for the general workforce. Contrast that with safety toe standards, where ASTM F2413 is the universally recognized and accepted industry standard that covers footwear for a wide range of jobs, from truck driving to warehousing to construction and manufacturing.
Servers, bartenders, janitors, chefs, grocery store clerks, clini- cal medical staff—all are professions that involve dangerous floor conditions. In these slick and slippery environments with contami- nants ranging from grease and oil to soap, water and chemicals, safety professionals need the proper data to define and qualify “slip-resistant footwear” for employee use in their company safety programs across all industries.
The goal: approved testing methods that approximate accurate measurements of the footwear’s slip-resistant safety in real-world environments.
The Coefficient of Friction (COF)
The standard method for evaluating the slip resistance of footwear is by determining its dynamic coefficient of friction (COF).
According to Introduction to Plastics Engineering, the coeffi- cient of friction is defined as: “The ratio of the force required to move two sliding surfaces over each other, and the force hold- ing them together.” 2 The COF can be either a static or dynamic measurement.
The difficulty in determining the slip resistance of occupational footwear in real-world environments comes from the three factors that, in combination, affect the scoring of COF:
1. Floor Type
2. Contaminants
3. Footwear
Dynamic COF measures the force between surfaces when one
or more of the objects are in motion, but herein lies the complexity. Reliable testing protocols must yield reproducible standardized re- sults, taking into consideration the relationship between the foot- wear, the contaminant and the floor type.
ASTM F2913 Slip Resistance Testing
ASTM International is one of the largest voluntary standards or- ganizations in the world. Its F2913 testing standard, developed in 2012, provides the current basis for measuring the slip resistance of footwear in action.3
ASTM F2913 testing produces a measurable, reproducible result, though there is no universally agreed-upon “magic safety number” when evaluating the slip scores themselves. However, it provides valuable data in evaluating footwear slip resistance.
Though it is true that, “to date no study has been performed
44 Occupational Health & Safety | JANUARY/FEBRUARY 2021
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