The global leading fabric in the disposable protective clothing industry is flash-spun polyethylene. In shorthand, the fabric is produced by mixing polyethylene with a solvent, pressurising it at high temperature and then extruding it through fine holes. During the extrusion process the solvent literally explodes or ‘flashes’ off, (hence the term flash-spun), leaving behind many fine polyethylene fibres which are then compressed into a flexible, dense sheet which combines the properties of strength, softness and liquid barrier (bearing in mind each of these terms is relative and subjective). It is also often described as ‘breathable’.
Its key competitor of the last ten years, microporous film, is a different, two layer construction, the inner layer being standard spunbonded polypropylene, and the outer being a microporous polyethylene film. This film has the structure of a sponge on a microscopic scale. There are no holes directly through it, but it consists of lots of tiny chambers, some of which interlock and overlap creating winding pathways through the fabric. This creates a fabric that combines the properties of strength, softness and liquid barrier (again bearing in mind each of these terms are relative and subjective). It is also often described, as we saw earlier, as ‘breathable’, though to what extent is uncertain.
SMS (Spunbound Melt-Blown Synthetic) material is a unique trilaminate material, of which there is a growing band of latter day variations such as SMMS, SMMMS or SMSMS. This, by contrast, really is breathable. A simple fabric-over-the-mouth test will readily demonstrate this and you can wear an SMS bag over your head and carry on quite normally all day long. SMS doesn’t have quite the same level of protection as spunbound polypropylene and microporous film combo, although - and this is important - it does still meet the requirements, and in many applications will provide perfectly adequate protection.
Different levels of protection
Globally, there are many different levels of protection used in working environments, but it is important to understand what levels of protection are available in terms of best practice internationally, and the standards to which the product protects to. In European standards the different levels of protection have been defined in terms of ‘Types’. Types relate to different groups of applications with similar properties - for example, whether they involve protection against dusts, liquids or gasses, and whether the liquid is in a strong spray or light splash form. The standards identify six Types to cover all eventualities - Type 1, Type 2 and so on, down to Type 6. In general terms Type 6 is the lowest protection level, namely “reduced liquid spray protection”.
A classic Type 6 application might be paint spraying, for example. There are so many variables in any individual application you care to name that it is difficult to be definite and specific about the parameters of any application. Hence all protective clothing recommendations come with a disclaimer stating that it is the user’s final responsibility to ensure the garment is suitable for the application.
Type 1 is the highest level protection being ‘gas tight’ suits - fully encapsulating suits which completely seal the individual against the environment. Type 2 is a similar construction but defined as ‘non-gas tight’, and requires a positive pressure to be maintained inside the suit by means of pumping air into it. In between the two extremes are various levels of liquid protection relating generally to the spray intensity and volume of liquid. The odd one out is protection against hazardous dry particles (that’s dust) and is defined as Type 5.
The European Types 1 to 6 should not be confused with the internationally recognised overall classification for Personal Protective Equipment (PPE), which in Europe is rated as classes. With Class 1 being ‘Simple’ products, relating to PPE not designed to protect against hazards and Class 3 being ‘Complex’ products, those designed to protect against hazards.
Bizarrely, and while not directly related to the particular subject discussed in this article, it is worth mentioning that the classification of individual fabric properties of garments, things such as tensile strength, puncture resistance, chemical permeation and the like, reverses the numbering system again so that the highest class is the highest protection level. In summary:
In overall Product ‘Classes’: Classes I to III The Highest Class number = Highest Protection
In application ‘Types’: Types 1 to 6, The Highest Type number = Lowest Protection
In fabric property ‘Classes’: Classes 1 to 5 or 6 (depending on the property), The Highest Class number = Highest Protection
So when choosing protective clothing the buyer needs to be aware of the international standards to which it complies and the protection it offers.
The garments most commonly used are those for Type 5 and 6 applications. Here the holes created by stitched seams are not, in most cases, critical, although the relative weakness of disposable materials means that poorly sized and/or poorly designed garments can result in problems when resultant stress on the seams opens up stitch holes, allowing ingress of harmful dusts or liquids. This is something users should bear in mind when considering very low priced garments. The major cost component of a disposable coverall is the fabric, and low prices are too often achieved simply by making the garment smaller and using less fabric - this can be an issue of safety as well as of comfort and durability.
Research before you buy
With the various levels of protection available, it is important to conduct some research before purchasing safety clothing because different industries have different requirements. By taking the various standards and factors into account, safety clothing can be designed so that it protects employees (or those affected by the activity) from the risks associated with the work activity.
Hazards that may require safety coveralls include: temperature extremes; adverse weather; chemical or metal splash; spray from pressure leaks or spray guns; impact or penetration; contaminated dust; excessive wear or entanglement of own clothing.
Options include conventional or disposable overalls, boiler suits, specialist protective clothing, for example chainmail aprons and high visibility clothing. In industries where there is a risk of fire breaking out during normal operation, flame retardant clothing is often worn to reduce the risks associated with this hazard. Such clothing can be expensive to clean and replace. Sometimes, the person is protected by means of a cheaper, disposable coverall worn over the top. However, flame retardant (FR) coveralls can be heavy and uncomfortable, especially in warm environments.
For those who work in welding professions, arch flash over-trousers, vests and jackets are an essential part of work gear. The fabric on these clothing items is very thick and durable, flame resistant and essential to preventing serious burns. Along with the overalls, trousers and jackets an arch flash hood, balaclava or helmet is also an essential component. The advantage of the hoods and balaclavas over the helmets is they provide a longer neck covering that fully protects the welder from burns. Some of these hoods have the option to have a built in air system, important for specific types of welding and for work in confined areas.
It is sometimes difficult to understand exactly what level of protection is best for employees without understanding the risks.
A project undertaken by scientists for the British Health and Safety Executive (HSE) project aimed to examine the effectiveness of various combinations of coveralls in limiting flame spread, with specific reference to the following questions:
Does the use of a disposable FR coverall impair the effectiveness of a FR coverall worn underneath?
Does the use of a FR disposable coverall provide effective protection from flame spread with a non-FR coverall beneath?
Is the effectiveness of a FR coverall impaired when a disposable non-FR coverall is used over the top?
Could a disposable FR coverall be used without any form of additional protection, thereby limiting the potential for heat stress?
Their project findings concluded:
The only single-layer sample to pass the criteria for limited flame spread listed in BS EN 531:1995 was the Proban-treated flame retardant coverall. Therefore, none of the other coveralls should be worn singly in areas where there is a risk of fire. Reduction of heat stress potential by moving from the use of conventional, reusable coveralls to disposables does not seem to be practicable
Using a disposable flame retardant garment to protect and prevent soiling of a reusable FR coverall appears practicable and safe in terms of limiting flame spread. However, this configuration may significantly increase the potential for wearers to suffer thermal stress
Of the other dual-layer tests, all but one failed to meet the criteria for limited flame spread. This combination should be treated with caution, however, since the manufacturer’s instructions state that this coverall should only be worn over an EN533 Index 2 or 3 garment, if exposure to flame is possible
Recommendations from the project included:
Dual layers of coveralls (disposable worn over non-disposable) should not be worn in areas where flame retardant clothing is required unless both coveralls are flame retardant • The manufacturer’s instructions on how coveralls should be deployed should be followed at all times
4 plumbers die
20 tradesmen die
6 electricians die
8 joiners die
…every week in the UK, according to the Health and Safety Executive (October 2010), as a consequence of exposure to asbestos dust while at work.
Asbestos is a real and relevant risk to today’s tradesmen. Any building built or refurbished before the year 2000 could contain the deadly substance.
One documented account of a worker noted that he first noticed he was ill in 2003, when he experienced breathing problems, sweats and couldn’t lie on his right side at night. Due to the pain he went to the doctor soon after, telling his wife he could be home that evening, but he didn’t return for a month.
After seeing the doctor, he was admitted to hospital where he underwent many tests before being diagnosed with mesothelioma. Chemotherapy and radiotherapy were arranged and he had fluid drained from his lung. The news of his condition came as a huge shock to both him and his family. Following the diagnosis, this worker suffered from depression, and also with the guilt of his mother’s death - she died from the same disease, contracted from washing her son’s overalls when he was serving his apprenticeship.
Lessons to be learned from this tragic case and others involving the laundering of contaminated coveralls are featured in recommendations of best practice discussed later.
Your protective equipment supplier should normally be able to tell you the type of protective material to select. Not all materials give protection against all chemicals. Some chemicals pass through protective materials over a period of time. It is important that you also ask your supplier how frequently the protective equipment needs to be changed. Ensure that the equipment is changed when necessary. Remember to train your workers and make sure they follow the instructions.
Check protective coveralls for damage both before and after use
Clean and maintain all PPE regularly
Use disposable protective coveralls only once and dispose of safely after use
Wash cotton type overalls on a regular basis
Wash overalls at work or at a specialist laundry. They should not be taken home and washed with the ‘family’ wash
Store protective clothing in a clean cupboard or locker
Store clean and dirty clothing separately
Provide a good standard of personal washing facilities
The material selected should be resistant to the penetration of liquids, dusts or granules as appropriate
For corrosive materials such as acids, an impervious apron gives good protection
Coveralls should normally be worn over boots rather than be tucked in
Gloves should normally be worn over the sleeves to help stop contamination getting on the inside of the PPE
Wear it well
According to the British HSE best practice workers should make sure they wear suitable protective overalls correctly when spraying biocides or pesticides. A study by the British HSE showed that leaving sleeves rolled up or zips undone will fail to protect workers from being contaminated with pesticides or biocides.
Research was carried out into the role clothing plays in reducing skin exposure to pesticides and to quantify the amount of protection given by different types of clothing, so that the information can be used by workers carrying out a risk assessment in the future. Researchers also wanted to establish what fraction of the amount of pesticides deposited on workers’ clothing actually reaches the skin.
The study used an articulated mannequin, which moved the way a typical worker would while using biocides and pesticides. Test fluids were sprayed on the clothing, mimicking patterns seen in the workplace. A series of replicate tests were taken using different types of clothing on the mannequin and with the clothing being worn incorrectly.
Significant decreases in skin contamination were achieved from all the types of clothing tested, including personal clothing such as a long sleeve shirt and a pair of jeans.
Wearing an extra layer of protective clothing such as a cotton boiler suit, further reduced skin contamination. However, there was still significant exposure to pesticides due to leakage around cuffs and collar and penetration directly through the fabric.
Specialist protective coveralls were shown to provide the best protection and reduced skin contamination to very low levels.
Specialist protective coveralls were shown to provide the best protection and reduced skin contamination to very low levels. Wearing specialist protective coveralls incorrectly such as leaving zips undone or sleeves rolled up, resulted in high levels of skin contamination.
Significant amounts of spray fluid were found on the workers’ normal clothing even though they wore a protective overall, which highlights the need for maintaining high standards of hygiene.
The study highlighted that when working with biocides and pesticides there is an increased risk of personal exposure if protective clothing is not appropriate or worn properly. It also demonstrated that protective clothing will be contaminated and should not be washed with domestic or personal items.
Body protection is important
Sometimes it is easy to forget about using the appropriate protective clothing, but the simple fact is that it helps protect individuals from accidents. With protective clothing the following important points need to be addressed:
Ensure that the appropriate safety standards are met by your safety clothing
Ensure that each item of protective clothing is appropriate for each particular workplace hazard
Ensure the clothing fits the individual worker
Provide/obtain training in the appropriate use of protective clothing
Provide/obtain additional training for supervisors to ensure they understand their role in enforcing wearing and use of protective clothing
Ensure all protective clothing is cleaned and adequately maintained
Protective disposable clothing
The value of protective disposable clothing is often dismissed by the argument “Why spend money on items that are going to be thrown away, when I can wash what I already wear?” What companies fail to recognise is the risk of contamination to normal clothing, and that disposable clothing eliminates this risk, while providing all over body protection.
Although many people work in professions that do not require any type of safety clothing, there are a huge number of people who rely on protective clothing items each day. These items are more than just designed to protect clothing underneath. They can also provide warmth, keep contaminants off the skin, resist cuts and abrasions and keep contamination out of products which may harm others (for example in food preparation). The right type of protection is important for workers on the job and safety managers should ensure employees are appropriately protected.
Ann Goodwin, Corporate Communications, British Safety Services
Published: 01st Jan 2011 in Health and Safety International