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Self-Contained Breathing Apparatus

Published: 13th Jul 2012

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Where extreme respiratory risks might be encountered, such as the possible presence of an irrespirable atmosphere, recourse is often necessary to the use of breathing apparatus (BA). In some such situations, breathing air is supplied via an airline rather than carried in a cylinder as a compressed gas. This has the obvious advantage that there is no need for the weight and bulk of the cylinder but, equally obviously, the disadvantage that the wearer is tethered by the airline which has to be dragged around the working area to allow a degree of mobility.

Any form of respiratory protective equipment (RPE) presents ergonomics’ challenges to the wearer but, in the case of BA, especially self-contained BA (SCBA) these are particularly acute.

Unlike other situations, where workers might respond to cumbersome or awkward PPE by not wearing it, this is seldom an option where BA is required – or at least, only once. This article explores some of these challenges – and offers some thoughts and suggestions for when SCBA in particular is needed.

Carry that weight?

As stated above, air-line BA has the obvious advantage that it does not require a heavy gas cylinder to be carried around. One obvious aspect of SCBA in comparison to other forms of RPE is the weight of the device.

Studies have shown that wearing SCBA can add around ten percent to the energy cost of carrying out an activity – an important consideration when strenuous work is required.

Recent years have seen the traditional steel cylinders replaced by lighter, fibre-wrapped cylinders which offer a potential weight advantage. This potential benefit is lost, however, where the weight lost is replaced by carrying extra air. While as far as air is concerned it is tempting to think ‘the more the better’, employers should ask whether or not that extra air – and extra weight burden – is necessary. If a brief inspection entry is all that is required, then perhaps a smaller cylinder could be used, making the SCBA lighter and easier to wear. It will also make the whole assembly smaller – which can be an advantage when entering a confined space.

Taking a balanced view

The weight of a full SCBA set can be a significant additional load, and strapping that load to your back before carrying out possibly heavy physical work – potentially including bending and lifting – can increase the risk of musculoskeletal injury, especially to the back. As well as providing another argument for not using a larger (heavier) cylinder than is necessary, where and how that weight is carried is important. Try to select a design of set where the cylinder fits snugly against the backplate and doesn’t stand proud; remember that the horizontal distance from the back to the cylinder will amplify the load on the back. As with rucksacks, it is now recognised that a design of SCBA set, where the cylinder sits lower on the back and some of its weight is supported directly through the hips, helps to reduce the load on the back and reduce the risk of injury. This works partly by transferring the weight through the pelvis instead of the spine, and partly by helping to minimise that all important turning moment when the wearer has to bend over when wearing the SCBA. The set should sit low on the back, with the waist strap sitting on the hips, so that part of its weight goes though there, and not through the shoulders.

Ooh! My back is stiff

Talking of bending over, would you strap a plank to your back before carrying out a manual handling task? Again, think about what your employees are going to be doing when wearing SCBA and consider whether one of the designs of SCBA with a more flexible backplate would be a good idea. It ain’t ’arf ’ot Mum In some situations, remaining in the adverse conditions for longer with a longer duration set might create additional safety hazards. For example, studies have suggested that in high ambient temperatures – such as those encountered by firefighters – the extra wear duration allowed by using a larger capacity cylinder mightmake all the difference in terms of the risk of heat stress, remembering that the extra weight as well as the duration will add to the risk. Having to withdraw because you are running out of air might provide an additional safeguard against overheating. See what I mean? So far this article has concentrated on the weight and bulk of the gas cylinder and backplate of the SCBA. First and foremost, however, the SCBA is worn to provide respiratory protection, and this means the use of a full-face mask covering the mouth, nose and eyes. Fortunately, most – if not all – SCBA masks are designed so that the dry incoming air flows over the inside of the visor. As a result, misting up, so often a problem with other eye coverings, is seldom an issue with SCBA. The visors are tested for clarity and being able to see clearly in the main field of view should not be a problem. Many visors cover a smaller area than the normal human field of view, however, resulting in a reduction in peripheral vision. Is this likely to be a problem? Could there be hazards around the working area which it is important for the wearers to see? If this is likely to be an issue, then choosing a design of BA where the face mask offers the widest possible visual field would seem sensible.

Size matters

When getting it right for the wearer, size can matter. With some forms of PPE, having the right size, correctly fitting the wearer, can be crucial for ensuring the correct level of protection. This is the case for the SCBA facemask. One size does not necessarily fit all and it might be difficult to obtain a good fit with a single size of ori-nasal assembly on all sizes and shapes of faces. Although seemingly less important because of the outer mask seal, this can lead to a loss of breathing air at times when the mask lifts away from around the mouth – or at the bridge of the nose. This can result in a reduction in the wear time. If it happens during exhalation, then moist exhaled air can leak into the outer mask, increasing the risk of the visor misting up. Two’s a crowd How many of us, when doing a DIY job such as fitting loft insulation, have found our glasses misting up on top of the dust respirator we are wearing? What have we done about it? Too often, the answer is to not wear one of the two properly, if at all. Where two or more items of PPE are worn at the same time, they might interfere with each other, either in terms of comfort or of performance. Is other PPE required for the SCBA wearer? Could this other PPE clash with the SCBA in some way? Obviously, anything else worn on the body, such as a fall-arrest harness, would be a problem and might require specially designed equipment – but what about other protective devices which have to be worn on the head? A safety helmet might not sit firmly on the face mask straps, causing it to become unstable. At best this might make it move about in use, causing distraction and annoyance to the wearer. At worst, it might become dislodged during some form of incident causing the wearer to lose protection at a critical time. Again, some styles of helmet harness are better than others in accommodating RPE straps. What about hearing protection? The cups of hearing defenders might overlap with the edges of the RPE face mask, breaking the seal of the defender and reducing the level of protection provided. Clearly ear plugs will overcome this problem – but they are not suitable for all wearers and applications, so again, some extra thought is required. Fortunately, the visors of SCBA face masks are tested for impact protection, but what about spectacles’ wearers? The arms of conventional glasses will pass under the face mask seal, making the two uncomfortable to wear together and possibly leading to inward leakage. There are styles of full-face respirator that can accommodate prescription glasses to overcome this problem. It’s good to talk Communication is always important, but how much do your SCBA wearers need to talk? Many SCBA face masks incorporate speech diaphragms to enable some communication, at least with colleagues in the vicinity. These are not always compatible with communications systems such as tannoys, however, and it might be difficult for wearers to make themselves heard and understood. Is an assembly with a built-in radio device needed? Think about the importance of the wearers being able to communicate with others not in the immediate working area – it might be a good investment.

It’s the law

Within the EU, problems such as these have been recognised for some time and requirements to take them into account are included in legislation. Thus Council Directive 89/656/EEC established the need for national regulation relating to the use by workers of PPE in the workplace, and Council Directive 89/686/EEC laid down further requirements on manufacturers selling PPE within the EU. In the UK, the provisions of the so-called ‘Use Directive’ have been incorporated into the Personal Equipment at Work Regulations 1992. Among other duties, the Directive requires all PPE to: • Be appropriate for the risks involved • Take account of ergonomic requirements • Fit the wearer correctly In addition, where more than one item of PPE is required, such equipment must be compatible and continue to be effective.

Help is out there

To assist in addressing these requirements a European Standard has been prepared (EN 13921), specifically on the Ergonomics of PPE. Although PPE is not directly tested against this standard it serves to provide guidance on the problems which can occur, and could be used by employers in the same way. In addition, within the UK, a standard specifically addressing the ergonomics of PPE ensembles for firefighters (BS 8469) has been published. Some brigades are already using the tests in this standard as part of their PPE selection process, helping to ensure that the PPE ensemble is ergonomically sound, as well as meeting technical performance requirements. Caveat emptor – buyer beware You might have carefully made the right technical selection for the level and type of risk identified in a workplace, and given detailed consideration to ergonomic aspects of the SCBA and the conditions in which it is to be worn. You may possibly have involved your workforce in that process – usually a good move. You probably think, therefore, that you have done everything you can, now you have bought the necessary equipment. You have even checked that it has the necessary identifier to show it has been certified as giving the correct performance – the CE mark in Europe. You have even saved your company some money by getting it for a ‘good’ price – e.g. cheaply. How would you feel, then, to discover that it wasn’t genuine, that it didn’t provide the necessary level of protection? In fact, that it might not provide any protection at all? Buying a fake handbag may be illegal but it is unlikely to be life threatening. Buying illegal, non-conforming personal protective equipment (PPE), however, could be the difference between life and death – or at least ill-health or disability. A wide variety of different forms of fake RPE (as well as other types of PPE) have been found on the market – including SCBA. Unfortunately, to the untrained and unsuspecting eye, illegal, non-conforming safety equipment is hard to distinguish and in many instances goes unnoticed until an accident occurs, often with irreversible consequences. Discovering that the cheap safety helmets you bought are fake could literally have shattering consequences, while the risks from fake SCBA could be fatal. In the UK, buyers can get help by purchasing through companies registered with the Registered Safety Supplier Scheme, introduced by BSIF (the British Safety Industry Federation) in 2009. They provide the following advice and guidance which will help buyers in other countries: “Take note of the price of the PPE. If it appears that the cost of the item is extraordinarily cheap then there could be good reason – shoddy workmanship, poor materials, to name but a few.” Another area to take into consideration is the look and feel of the product. In many instances just by carrying out a thorough inspection of the item you might be able to detect noticeable defects. Checking the labeling on the product can help verify the product as being genuine and legal. Is the CE marking present on the product labelling and displayed in the correct font and at least 5mm high? Again, documentation is also necessary. Have written instructions been provided in clear and legible text? It is a requirement of the PPE Directive that the instructions for use are precise, comprehensible and provided at least in the official language(s) of the Member State of destination, e.g. the country in which the product is sold. Also, is the name and address of the manufacturer detailed on the user instructions? Clearly, being sure that you are buying from a reliable and reputable source can help make this job easier. If you are still unsure, the supplier of the product should be able to provide you with an EC Declaration of Conformity or EC-Type Examination Certificate for the specific product in question.

Published: 13th Jul 2012 in Health and Safety International

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Richard Graveling is Principal Ergonomics Consultant with the Institute of Occupational Medicine (IOM). Last year the IOM received the President’s Medal of the Institute of Ergonomics and Human Factors in recognition of their research and consultancy work on t...
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