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On Your Feet?

Published: 10th Nov 2008

The onus is on the individual to follow procedures.

Just about everyone knows what we mean when we talk about 'safety boots' ....or do they? Hidden behind this familiar and widely used term are several layers of complexity, which can lead to confusion and misunderstanding, which can in turn lead to significant injuries or, in extreme circumstances, death.

  • Three types of footwear for use in working situations are described in current European Standards. All of them provide some degree of protection against a selection of hazards, and all can loosely be described as “safety boots”. However, the levels of protection provided by the different types against specific hazards differ significantly; using the wrong type of footwear may increase the risk of injuries arising from these hazards may change or increase
  • None of these three types of footwear guarantee the “safety” of the wearer against all hazards; the term falsely implies a degree of invulnerability for the user. In other areas of personal protective equipment (PPE), the word “safety” (as in “safety helmet”, “safety spectacles” or “safety harness”) is being phased out in favour of more explicit and honest terms like “protective”. With footwear even this simple substitution causes problems, as we will see below

What protection is available?

For decades, European Standards defined three types of footwear for use in working situations. More recently (2004 onwards), European and International Standards have harmonised to describe the same three types of footwear. In order of increasing level of the protection provided against crushing and impact injuries to the toes, these are:

Occupational footwear

- Covered by EN ISO 20347 and marked “O”. In their basic form, these are essentially just a reasonably tough boot or shoe - the sort of thing your mother would probably have considered to be “sensible shoes” which has no particular strengthening of the area around the toes.

Protective footwear

- Covered by EN ISO 20346 and marked “P”. These have everything that Occupational footwear has, plus a toecap with moderate resistance to impact and crushing. This is where the simple substitution of “protective” for “safety” in the commonly used terminology becomes problematic, because “protective footwear” has this specific meaning.

Safety footwear

- Covered by EN ISO 20345 and marked “S”. These have everything that Occupational footwear has, plus a toecap with higher resistance to impact and crushing. Here “Safety” (with a capital “S”) has a defined meaning, which may be different from what is meant by “safety footwear” (with a small “s”) in commonly used terminology.

For all three types of footwear, a wide range of optional additional forms of protection is available, over and above that provided to the toes. The whole situation is summarised in Table 1.

This table leaves out the further complications caused by restrictions on the shape and composition of footwear within a given type. Suffice to say that not all of these protective properties can be claimed by every possible type, shape and construction of footwear. Certain groupings of these optional types of protection can be denoted in shortened form, as described in Table 2 - this is done for ease of marking on the footwear, and ease of reference when specifying appropriate equipment for particular applications.

Performance characteristic Occupational footwear “O” Protective footwear “P” Safety footwear “S” Marking on footwear
Basic mandatory requirements for construction and strength Mandatory Mandatory Mandatory B
Fuel oil resistance Optional Mandatory Mandatory FO (on type “O” only)
Toecap impact - 100J 200J -
Toecap crush - 10 kN 15 kN -
Sole penetration resistance Option Option Option P
Electrically conductive Option Option Option C
Antistatic Option Option Option A
Electrically insulating Option Option Option I
Heat insulating sole Option Option Option HI
Cold insulating sole Option Option Option CI
Energy absorbing seat Option Option Option E
Water resistant footwear Option Option Option WR
Metatarsal protection - Option Option M
Ankle protection Option Option Option AN
Water penetration and absorption resistant upper Option Option Option WRU
Upper cut resistance Option Option Option CR
Heat resistant outsole Option Option Option HRO
Cleated sole Option Option Option -

Marking following “O”,“P” or “S” Meaning (see options in Table 1) Applies to footwear made from:
B Basic minimum mandatory Leather + other materials
1 B + A, E Leather + other materials
2 1 + WRU Leather + other materials
3 2 + P, Cleated outsole Leather + other materials
4 B + A, E All rubber or polymerics
5 4 + P, Cleated outsole All rubber or polymerics

Beyond these requirements for footwear providing protection in general working situations, there are a number of further standards describing footwear specifically intended for protection against the hazards which arise in particular working activities. Taking the general footwear standards as the starting point, these build on the necessary protective performance by including additional tests and requirements for applications such as:

Firefighting footwear: EN 15090, which will be marked with “F” and other performance-related symbols. This takes the basic requirements of either O or S footwear, makes various other optional properties from the general standard mandatory (such as resistance to fuel oil, and electrical resistance properties) and adds resistances to flame, hot contact and radiant heat.

Footwear for chainsaw users: EN ISO 17249, which will be marked with a chainsaw pictogram and other performance-related symbols. Starting with the requirements of EN ISO 20345 Safety footwear, specific tests and performance requirements for resistance to brief accidental contact with a still moving but unpowered chainsaw blade are added.

Footwear resisting chemical exposures: EN 13832 parts 1-3, which will be marked with a chemical flask pictogram and other performance-related symbols. Footwear of type O, P or S, in the form of Wellington boots, must pass testing against a number of substances drawn from a list of 15 chemicals.

Resistance to degradation of the footwear (no significant loss of mechanical strength or softening / stiffening of the footwear materials) must be proven for at least two of the listed chemicals (EN 13832-2). For footwear classified as “highly resistant” to chemicals (EN 13832-3), the resistance of the footwear to degradation must be proven for at least 3 of the 15 chemicals, and permeation through the footwear materials for the same chemicals must not occur in less than 2 hours of continuous exposure.

Permeation is when the chemical passes through the barrier material by molecular diffusion, without necessarily damaging the material itself. After the chemical has permeated through the footwear material, the wearer will be exposed to it, even though the footwear may appear undamaged. The underlying implication of the permeation test is that protection against chemicals is strictly time-limited - sooner or later the chemical WILL get through to the wearer.

The implication of all this information is that just posting a sign saying “SAFETY FOOTWEAR MUST BE WORN” (with or without a capital “S”) is insufficient. Much better specification of exactly which of the protective options available for footwear are actually needed is essential.

Interactions

For footwear designed for specific applications, it is vital to consider how the footwear interfaces with the other clothing and equipment that the user is wearing. For example, tucking the legs of coveralls inside the top of a boot bypasses any protective function that the footwear may have against splashed liquids or hot / burning debris.

The other crucial interaction for footwear is that between the sole and the flooring surface on which it is used. Adequate control of this interaction requires much more than having a good and well defined cleated sole, which is all that footwear standards currently specify.

Slip resistance

When selecting footwear for use at work the slip resistance of the footwear is rarely directly considered. Choosing the right slip resistant footwear for the right situation can help to significantly reduce slip accidents. There are a huge variety of shoes and boots available that are marketed as slip resistant, but it can be difficult for a prospective buyer to identify which footwear will perform well in their work environment.

Some footwear that is marketed as slip resistant may not have been tested at all, others may have been tested in conditions that do not accurately reflect the potentials buyer’s work environment, which can make it difficult to identify footwear that will perform well in real workplace conditions from brochure descriptions. The UK Health & Safety Executive (HSE) recognises the difficulty that employers can have in identifying PPE footwear with good slip resistance and have developed their own test for assessing the slip resistance of footwear.

Ramp Test Method

Reliable information on the slip resistance of specific flooring / footwear combinations can be obtained using a ramp-based coefficient of friction test. A version of this test method has been developed by the Health & Safety Laboratory (HSL), HSL-PS-SOP12, also known as the UKSRG Ramp Test (HSE, 2007), which is shown in Figure 1.

Two different contaminants are routinely used; the first uses potable water at a flow rate of approximately 6 l/min and the second uses glycerol, 100 ml of which is applied to the floor at the beginning of each test. These volumes are designed to achieve saturation of the surface and maintain this level of contamination throughout the test. The HSL-PS-SOP12 procedure is as follows. Starting with the floor surface horizontal, the operator increases the inclination of the ramp in approximately 1° increments until an unrecoverable slip is initiated and the angle of the ramp is recorded. Twelve angles at which this slip occurs are determined, with the highest and lowest values being discarded. The 10 remaining values are then averaged to give the critical angle. The coefficient of friction for level walking is then determined by taking the tangent of the critical angle. Ramp data is interpreted using Table 3:

Ramp Coefficient of Friction Slip Potential
0 – 0.25 High Slip Potential
0.26 – 0.35 Moderate Slip Potential
0.36 + Low Slip Potential

Case Study: Oil company protects ankles AND guards against slips

A UK oil company was concerned about the number of ankle injuries suffered by staff wearing loose-fitting rigger boots on their exploration and production sites both onshore and offshore. The company investigated close-fitting lace-up boots as an alternative and identified three types which gave good ankle support. They then made it mandatory that staff and core contractors to their sites wear one of the selected types. However, although the new boots did help to reduce ankle injuries, staff wearing them reported some concerns about increasing numbers of slips. The Health and Safety Laboratory (HSL) therefore studied the slip resistance properties of their ‘approved’ footwear and made recommendations on its suitability.

HSL tested four types of boot - types A, B, and C were on current issue and D was being considered for inclusion in the list. HSL utilised the HSL ramp test on three different floor surfaces using a continuous, pressurised water spray as the contaminant. The diversity of sole patterns is clear from Figures 2 and 3. They conducted grip tests on two regular site surfaces - gratings and scaffold boards - and compared them against the surface (sheet steel) used in the standard test.

All boots performed well on gratings and scaffold boards (although the materials were brand new and may not have been representative of the condition of these surfaces at site locations). However, boots A and D performed poorly when confronted with the ‘more challenging’ conditions of the standard test. Boot A also gave little?grip feedback to the operators. Boot C was reported as the most comfortable boot during the tests, and B was reported as being less comfortable at high ramp angles (i.e. when walking down a slope).

The company decided to remove boot A from their list and not to adopt D (with the current sole unit) into their range. This helped to relieve staff concerns about slips, and the company decided to keep B and C.

The company also decided to adopt the HSL standard test as the method of assessing grip capability of future footwear proposed for their ‘approved’ range. The acceptance criterion is that all footwear will perform above a minimum coefficient of friction of 0.24 (indicating moderate slip potential) in the standard test before being considered for their range. The company have charged their footwear supplier to challenge manufacturers to produce better footwear, which meets the new specification for grip and comfort, and they have responded by providing some new products for testing by HSL and subsequent trialing by staff.

This case study shows that footwear selection should not be based simply on one feature - ankle protection in this case - and that it is prudent to test the slip resistance of a range of footwear to assess how they meet all the necessary criteria, on surfaces likely to be encountered in the particular workplace.

To summarise, this case study shows that it is important to take the anti-slip performance of footwear into consideration when selecting PPE. The right footwear for the environment can drastically reduce slip accidents. More information on the anti-slip performance of a range of safety and occupational footwear can be found at the HSE website: http://www.hse.gov.uk/research/hsl_pdf/2007/hsl0733.pdf.

What footwear can’t do

So far, we have concentrated on what these types of footwear can do. It is however important to recognise that the types and levels of protection that they provide is strictly limited. Just like any other form of PPE, these boots are not some kind of magic talisman which wards off the evils and dangers in the workplace. While this may seem obvious, some queries received, and also direct observation of working practices and investigated accidents, suggest otherwise:

  • An enquirer asked what type of footwear was appropriate when manoeuvering 4 tonne concrete blocks. Given that the best level of toecap compression resistance recognised in the standards equates to 1.5 tonnes, the correct answer is “none”, if this is going to be the only means of controlling the risks
  • Commonly observed practice when moving heavy wheeled machinery, or rolling heavy cylinders / drums, is to use the toecaps of safety footwear as temporary chocks or wedges to prevent, stop or steer the movement. This is a highly risky practice and amounts to gross misuse of the PPE, which is contrary to health and safety legislation in every country which has such laws.
  • Chainsaws have evolved over the years into highly efficient cutting machines, optimised for slicing through tough materials with ease. This fact must be considered in the context of the expectations of some users who defeat the very modest protection that is possible with a chainsaw resistant boot. Typical statements would include “These boots are supposed to protect me. They are guaranteed.” As indicated earlier, the testing of chainsaw boots simulates brief accidental contact with the still moving but unpowered blade of a chainsaw. There is no claim or expectation that they can resist the onslaught of a powered blade, and with just a little thought this should be obvious.
  • When cleaning the inside of a tank using a caustic soda solution, a worker sustained serious corrosive burns to his feet (amongst other places). He was wearing good quality chemical protective Wellingtons and chemical splash protection, which was properly interfaced at the boot/leg junction to prevent splash running into the boots. However, in this case, the caustic liquor built up in the bottom of the tank to a depth which exceeded the height of the Wellingtons, and overflowed into them PPE, including the types of footwear considered in this article, is not and never can be a substitute for a careful consideration of the risks.

Selling the product

No PPE will be effective if wearers don’t use it. Key factors in gaining user acceptance for wearing PPE are appearance and comfort. Criticisms which have been levelled at footwear in the past are that it is too big, too stiff, heavy, and unattractive. Inevitably, where high levels of protection are being provided, there is going to be some increased burden on the wearer, but there is nothing in the relevant standards which makes this burden inevitably high. If manufacturers can produce footwear which achieves the necessary performance without bulk, weight or rigidity, and can package this in an aesthetically pleasing way, it is much more likely to be used, and used correctly.

Correct sizing is a big part of comfort. There are few things more uncomfortable than badly fitting new shoes. Conversely, there are few things more reassuringly comfortable than a well broken-in and properly fitting pair of shoes. No doubt this dichotomy contributes to the tendency of many wearers to retain their old safety footwear long beyond the time when it should have been replaced. Routine examination of footwear should be carried out, just as for any other form of PPE. Worn out or damaged uppers, soles or linings, exposed toecaps and broken fastenings should all prompt replacement.

Sizing is one area where there is room for some improvement among manufacturers. With the globally increasing diversity of the workforce, there is a present and growing need to cater for a greater proportion of the population. This means increasing the range of foot sizes (length and breadth) in which safety footwear is manufactured and supplied. There are already many workers at the extremes of the population size range who have great difficulty in obtaining proper foot protection.

With the introduction of high performance synthetic materials and composites, some of the disadvantages of traditional components for protective footwear (weight of steel toecaps; weight and stiffness of steel penetration-resistant sole inserts; incompatibility of metal components with electrical induction/magnetic-sensitive applications) have been reduced, while still meeting the necessary performance levels in the standards.

A glance at any of the manufacturers’ catalogues will demonstrate that they are fully aware of the need for footwear to look good. In many cases high performance safety footwear is now almost indistinguishable from street or leisure footwear. However, this does cause problems for supervisors or health and safety inspectors, who need to ensure that appropriate PPE is being used where needed. In the past, simply looking at someone’s boots would be enough to tell whether they were appropriate. Now, with the similarity between proper safety boots and ordinary footwear, closer scrutiny of the markings and designation on the footwear is necessary.

The message here is that proper safety footwear does not have to be heavy and uncomfortable, leaving you tired and aching at the end of a shift. Neither can it unconditionally protect you from every hazard in the workplace. The onus is still on the individual to be sensible about the risks and to follow appropriate procedures.

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Published: 10th Nov 2008 in Health and Safety Middle East

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