The correct footwear will have a positive effect
Of all accidents in professional and non-professional life, slips, trips and falls are the most frequently occuring.
Slip, trip and fall accidents are the most common cause of major injuries at work. They occur in almost all workplaces, 95% of major slips result in broken bones and they can also be the initial causes for a range of other accident types such as falls from height.
The causes that trigger fall accidents, are often minor events, e.g. a truck driver jumping out of the cabin, or a doormat that causes trips, an oil slick in the garage or bad lighting in a parkhouse staircase.
The range of accidents is wide and there is a number of reasons why these occur. One can distinguish soft factors and hard factors. Hard factors are uneven or slippery or dirty floors, unsuitable footwear, bad visibility of pathways and stairs, or use of unsafe ladders. Soft factors are human factors such as hectic pace, running, the well known habit of leaving things lying around on the floor, improper fixture of cords and computer network cables in the office, or lack of concentration when using ladders.
Nearly one in five registered accidents in occupational life is a slip, trip or fall accident. In Germany alone, about 5000 people per year suffer severe accidents, with the consequence of permanent harm and physical impairment. In total (occupational and non-occupational environment), there are in Germany about 7000 fatal accidents due to fall accidents. The cost equivalent for the non-performed working time is about 8 billion EUR.
The factors which have an influence on slip accidents are numerous:
- Environmental factors (climatic, visibility, temperature, etc.)
- Physical and mental condition of the person
- Outsole of the shoe (material, design)
- Wear of the outsole
- Slippery-ness of the floor (viscosity of the lubricant, thickness)
- Floor (surface roughness and material)
Personal Protection – Footwear
The request for prevention of falls due to slips is one of the essential health and safety requirements in European Legislation. In Directive 89/686/EEC it is related to the footwear as well as to the flooring.
What is protective footwear?
The term protective footwear covers:o Safety footwear (shoes with toecaps, of which the resistance to compression has been tested with a test energy of 200 J)
- Protective footwear (shoes with toecaps, of which the resistance to compression has been tested with a test energy of 100 J)
- Occupational footwear (shoes with protective features)
Safety footwear, protective footwear and occupational footwear are personal devices the purpose of which is to protect feet from external detrimental influences.
In line with the European legislation mentioned above all footwear which serves, among others things, the purpose of preventing slip accidents is by definition protective footwear in terms of Personal Protective Equipment. A type approval certificate issued by a notified body is obligatory before putting these products on the market. The outsoles of protective footwear must be designed in a way that they provide purchase to the floor, either by friction or by grip. One means of demonstrating conformity to the European Legislation is to fulfill the requirements of the European Standards for safety footwear.
- EN ISO 20344, Personal protective equipment – Test methods for footwear (ISO 20344:2004)
- EN ISO 20345, Personal protective equipment – Safety footwear (ISO 20345:2004)
- EN ISO 20346, Personal protective equipment – Protective footwear (ISO 20346:2004)
- EN ISO 20347, Personal protective equipment – Occupational footwear (ISO 20347:2004)
The three basic shoe types (safety footwear, protective footwear and occupational footwear) serve different purposes and have different fields of application.
Identical basic safety requirements are required to be fulfilled by all three shoe types. These requirements are relevant to the upper, the lining, the tongue, the insole and the outsole as well as the shoe as a whole. Safety footwear in line with EN ISO 20345 fulfill a set of higher requirements as specified in the standard.
Classification of footwear
The three types of footwear are subjected to a further two differentiating classifications reflecting different materials:
I: Shoes of leather or other materials made according to conventional shoe methods (e.g. leather shoes)
II: Completely moulded or vulcanised shoes (wellington boots, polymer boots – e.g. made of polyurethane (PUR) – for wet environments).
Specific requirements are specified for each of the two classifications.
The standards EN ISO 20345 to EN ISO 20347 offer a wide range of marking combinations.
The table shows marking categories from SB to S5 for safety footwear with the most widely used combinations of basic and additional requirements for I and II classification.
The suitable footwear can be selected from the table above according to the determined requirements based on a risk assessment.
It is to be noted that slip resistance is not included for the time being in the table. Related to the characters used in the columns for classification grades:-
I: Leather shoes or shoes of other materials made according to conventional shoe methods (e.g. leather shoes)
II: Completely moulded or vulcanised shoes (wellington boots, polymer boots – e.g. made of polyurethane (PUR) – for wet environments).
It is compulsory to meet the marked safety relevant basic and additional requirements according to Tables 1 and 2.
If conformance to the basic safety and health requirements according to the Directive 98/686/EEC (PPE-Directive) is ensured by meeting the harmonised standards the footwear must in addition to the CE symbol be marked according to the standards of the EN ISO 20345 to EN ISO 20347. This marking must include:
- The shoe size
- The manufacturer’s identification mark
- Manufacturer’s type designation/the manufacturer’s article number
- The year of manufacture
- The number of the European standard, e.g. “EN ISO 20345”
- The marking symbols of Table 2 or the letter symbols of Table 3 are to be used for any provided additional safety relevant devices
The CE symbol consists of the letter symbols “CE” (“CE” = Communauté européenne = European Community).
Safety, protective and occupational footwear are at least classified with the category II certification. An EC type examination must have been issued for them.
The analysis of accidents results in a special main emphasis on accidents with falls. A large number of such accidents is caused by slipping during walking. The causes for slipping are varied. They are especially to be found in the make up and fouling of the floor or the grounds, in the form of footwear and in the construction and wear of the outsole.
Slip resistance is therefore a key element for safety of footwear, all shoes worn as footwear should be provided with anti-slip soles.
However, within these harmonised European Standards no concrete requirements nor test methods for the determination of slip resistance are given. Thus, slip resistance does not form part of the categories in the tables above. The reason is that there are numerous influencing factors and different ways these effect the slip resistance. Furthermore, there were in the past different views in the member states of the European Community as regards to the applicable test methods.
CEN, the Europeen Committee for Standardisation based in Brussels, has taken an effort to tackle the problem and to elaborate as a first step a harmonised Europen Standard for determination of slip resistance. In 2004, CEN has published the harmonised European Standard EN 13287. According to EN 13287, this European Standard specifies a method of test for the slip resistance of conventionally soled safety, protective and occupational footwear.
Principle of test method
The item of footwear to be tested is put on a surface, subjected to a given normal force, and moved horizontally relative to the surface (or the surface is moved horizontally relative to the item of footwear). The frictional force is measured and the dynamic coefficient of friction is calculated. To simulate the movement when walking, the test sequence is to be performed in at least one of the three different modes: o Forward heel slip at angled contact o Backward slip on the forepart o Forward flat slip For the heel and forepart test modes the footwear shall be fitted onto a defined shoemaking last. For the flat test mode the footwear shall be fitted onto a defined artificial foot.
The test sequence is performed with different defined lubricants (Glycerol, aqueous solution with a viscosity of (0,2 ± 0,1) Pa s, or detergent solution, containing a mass fraction of 0,5 % sodium lauryl sulphate in demineralised water). The reference floors specified in the standard are steel floor, consisting of a stainless steel plate, such as steel Number 1.4301, Type 2G (cold rolled, ground), and pressed ceramic tile floor of defined surface roughness.
At least one item of footwear of each of the smallest, middle and largest sizes in the manufacturer’s size range shall be tested. This leads to a large number of possible combinations between shoe / lubricant / floor. Before performing the test, prior to use and before applying a new lubricant, the surface shall be cleaned using an ethanol solution. The sole of the shoe shall be abraded by rubbing it with silicon carbide paper wrapped around a rigid block exerting minimal pressure. It is intended that only superficial abrasion should be applied that does not significantly change the tread pattern nor the surface texture of the sole, and that produces a final visually uniform appearance over the whole area of the sole that will be in contact with the floor during the test .
The test method according to EN 13287 is, compared to other methods, objective and cheap. However, there are some deficiencies. First of all, it is recognised that this test method only insufficiently reflects the influencing factors and the mechanisms that influence slip resistance. Furthermore, there are for the time being no agreed limit values for the coefficient of friction. The test combinations between outsoles, sizes, lubricants and floor materials are numerous, which may rapidly increase test costs. For slip resistance, it is not a criterion per se whether the outsole is cleated or not; this has to be assessed in view of the underground on which the footwear is intended to be used. However, the standard does not give any requirements nor test criteria for the assessment.
This test method produces abstract test results, which are not immediately applicable to concrete problems. That means that “real live” situations require the determination of other parameters, and the asssessment of their effect on slip resistance, e.g. different floors (indoor and outdoor), shoe forms, temperature, material of outsole and wear of sole, the movement on stairs or walking along a curve. The abrasion of the outsole prior to testing has an effect on the coefficient of friction and its reproducibility is not well defined.
health at work Prior to the selection and use of footwear or leg guards the employer must perform an assessment of the working conditions (also service work conditions), which especially includes o Type and extent of the hazards, o Duration of the hazard o Personal requisites of the person that will use the footwear. Slips, Trips and Falls The use of every footwear must depend on the type of expected hazard. Their types are known but when they actually occur can, however, not be predicted.
For this reason footwear must be used for prevention in all situations in which a hazard cannot, as far as anyone can judge, be excluded. Selection example – Service shoes Which type of footwear should be worn in service jobs? The following requirements must be stipulated based on the risk assessment. Service shoes are worn e.g. in restaurant and similar services. Continual walking and standing put a great strain on feet. Injuries to feet can result by slipping on a wet floor or on spilt food. These hazards can be counteracted by wearing suitable footwear.
Only footwear in line with the EN ISO 20347 standard are to be worn in the serving fields of work. These shoes should meet the following additional requirements:
- The footwear should be closed in the heel and the toe areas and the form of the shoe should be low (shoe forms A or B) and lightweight.
- Anti-slip outsole coating,
- Heels with a sufficiently large tread and a moderate height,
- A flexible outsole that adapts itself to the natural movement of the foot,
- A secure fit around the foot
- A damping system for the heel and
- An anatomically shaped footbed
- Duration of use (service life)
The duration of use of footwear and leg protection depends on the stresses and the care they are subjected to. Shoes not in a state according to regulations, e.g. with worn profiles, bare toe caps or broken open shoe seams must be withdrawn from use.
Maintenance, repair and replacement measures
Worn outsoles have a major impact on slip resistance. Slip resistance normally decreases when outsoles are worn. The wearer must inspect the footwear for wear and visible defects. It is not permitted to continue wearing worn out or damaged footwear and leg protection. The employer must be informed of defects.
Thomas Von Hoegen Thomas von Hoegen works for DIN, the German Institute for Standardisation, in Berlin, Germany. He is responsible for the German Personal Protective Equipment committee and is secretary of CEN/TC 162 “Protective clothing including hand and arm protection and lifejackets” DIN e.V. 10772 Berlin, Germany Tel: +49 30 2601 2829 e-mail: [email protected]
Published: 01st Jul 2005 in Health and Safety International