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Confused or Confined?

Published: 10th May 2009

In the 26 years I’ve been working in confined spaces, the practices we employ to ensure our safety have changed little. Attitudes and legislation, however, have changed dramatically and sometimes I wonder why.


In 1961 a piece of legislation called the Factories Act included a section (30) on working in confined spaces. The title was confusing as it really referred to the possibility of encountering such things as dangerous atmospheres or high temperatures, and had little relevance to the size of the space you worked in. From that point onwards the die was cast and today, 48 years on, we still get the mistaken conception that a confined space is somewhere small and tight and difficult to move around in.

Admittedly many of the confined spaces we work in today are small and tight and difficult to move around in, but these are not essential characteristics. The legislation of 1961 (a similar piece of legislation existed for the construction industry) laid down specific controls that employers and employees must adhere to whilst working in confined spaces. These controls related to analysis of the atmosphere, breathing apparatus and access equipment, much of which was inoperable from a practical point of view.

As an example, one requirement to use full working breathing apparatus (the type commonly worn by fire brigades) conflicted with the minimum size opening of a 16” by 14” oval, unless you were really skinny!

The result was that many employers shied away from the idea of working in confined spaces, either not complying with the legislation or by using something more reasonable to work “as safe as reasonably practical” in what could be a difficult environment. There was even a policy of not describing situations as confined spaces - by this means you did not need to follow the regulations and work became easier to carry out. This spawned countless different titles for what were essentially confined spaces. “Enclosed space” was a common one, “gas check area” another - anything other than “confined space”. And this attitude still exists today within those of us of a more mature age: there is a fear of calling the confined space what it is so that we can get the job done, when really all we needed to do was to take reasonable precautions to deal with the risks associated.


In 1997 a new piece of legislation was brought out that made it much simpler to carry out work and comply with the law. The Confined Spaces Regulations 1997 and their associated ACOP and Guidance pointed to the employer to carry out a risk assessment and decide what constituted as “reasonable”. Hurrah - at last we can call confined spaces what they are!

There was even a new definition “any place, including any chamber, tank, vat, silo, pit, trench, pipe, sewer, flue, well or other similar space in which, by virtue of its enclosed nature, there arises a reasonably foreseeable specified risk”; they then proceeded to give us a list of specified risks.

“Specified Risk” means a risk of – (a) serious injury to any persons at work arising from a fire or explosion (b)without prejudice to paragraph (a) -

  • the loss of consciousness of any person at work arising from an increase in body temperature
  • the loss of consciousness or asphyxiation of any person at work arising from gas, fume, vapour or the lack of oxygen

At last, simple definitions, guidance that could be followed and an ability to work safely whilst still getting the job done. But be careful - the Channel Tunnel can easily be described as a confined space, enclosed with the possibility of fire or explosion. And many of our own loft spaces will build up sufficient heat during a summer’s day to produce problems. All we have to do is complete the Risk Assessment, develop the Safe System of Work and get the people involved competent to conduct the work. I’ll come back to the last bit later because that’s my speciality. In the meantime let’s look at the Risk Assessment.

Simple principles have always existed for working in confined spaces and we’ll discuss each one separately, but remember you can use any or all of these principles to deal with the dangers you foresee in a confined space: it’s the unforeseen ones you really have to watch out for.

If you look at the specified risks listed above, they can be broken down into four main areas: atmospheric; drowning; heat; and free flowing solids. The precautions for each are easily identified but before we start: what’s the easiest way of avoiding the dangers of confined spaces? Don’t go in!

“Don’t go in” may seem a simple idea, but in the majority of cases people ignore what is the simplest form of protection i.e. don’t expose yourself to the danger. The use of remote tools such as cameras in sewers or long arm equipment will often negate the need to enter a confined space. In situations where a regular entry into a confined space is required it makes even more sense to install this type of equipment. I remember a situation where an employee had to enter a hazardous atmosphere 4 or 5 times a day in order to operate a valve. After discussions with the employee, 8ft of steel bar and 2 bolts resulted in the employee being able to operate the valve from outside the confined space.

If we have to go in then we should be able to do so with confidence, knowing we have taken adequate precaution to protect ourselves from the hazards we are likely to face.


The hazard most commonly associated with confined spaces, principally because of their nature as an enclosed area it is probable that they have limited ventilation. Often below ground or with an opening on the top, confined spaces are therefore likely to hold denser than air gasses. Even situations with larger openings can still create an issue if the level of dangerous gasses can build up quickly, as in the Abbeystead disaster of 1984.

Initially if there is a hazardous atmosphere present, ventilate if possible: diluting the gas will not get rid of it, but will hopefully maintain the level at something more manageable. Then monitor the levels of gasses accurately, looking in turn first at the oxygen levels. 19% to 23% is the recommended range from the HSE, the 19% coming from the mining industries experiences. Remembering too that the modern gas monitors will look for the Partial Pressure of the oxygen in the atmosphere, so pressurised situations will skew your results.

Then look at the flammable levels, again being aware that many detectors need sufficient oxygen to operate, ensuring a reasonable safety factor below the Lower Explosive Level (the level at which the mixture is sufficiently concentrated enough to explode). Many will set a limit at only 10-20% of the LEL ensuring, if gas arises, a reasonable chance of getting out before it goes POP.

And at this point don’t forget the differing densities of gasses: methane is roughly half as dense as air and will separate very quickly rising to the top of any chamber and forming pockets in situations where it can get trapped. Butane conversely is very dense, so dense in fact you can carry it in a bucket, though a lid would be useful to stop it spilling (only joking).

Finally, an investigation into the possibilities of toxic gasses being present. In many cases employers will know of the existence of the toxic gas: the plant or equipment involved may have contained the gasses originally, having been used to store or transport the chemicals involved. In other situations it may be that the gasses arise as a result of a process that has occurred, deliberately or otherwise.

In some cases it will be leaks, spillages or just downright negligence that has given rise to the presence of toxic gasses in the confined space. Monitor carefully and continuously try to reduce the levels of gasses to below the Workplace Exposure Limits laid down by the HSE. Remember exposure to these sorts of gasses will initiate a COSHH risk assessment, so be careful with your paperwork as Permits used to deal with confined space work may form part of your COSHH records. If you can not guarantee an atmosphere will stay safe, consider breathing apparatus, either to carry in case of emergency (escape breathing apparatus) or full working breathing apparatus to enter with it on.

Check the protection factor offered by the B.A. and always ensure the employees can get in and out with it on. Airline B.A. is often easier to enter with, though not as versatile when it comes to travelling about in the confined space. Forget respiratory protection that relies on filtration, it won’t add any oxygen to the atmosphere.

Finally, on the atmospheric front, at least for the comfort of employees if nothing else, try to change the air in a confined space at least 5 times an hour, making an environment more pleasant to work in will, more often than not, make the job go more smoothly and be easier.


If someone on the outside of the tank you’re working in opens the water valve and fills it up, you can just float to the top and climb out! Too simple to be true and it often is. Unfortunately this sort of accident in confined spaces seems to be on the increase, whilst atmospheric situations are fortunately becoming less common. In many cases we can virtually eliminate the example above by proper isolation: locking off, tagging and pipe work disconnection where possible.

But this isn’t always possible, such as in live sewers, where an increase in flow is always a risk even if it’s not due to rain. Watchmen stationed upstream may seem an old fashioned precaution but the simplest ideas are often the best. Someone controlling pumps and valves, and even checking tides can all reduce the chance of a nasty surprise and two wet feet.

The regulation says “drowning of any person at work arising from an increase in the level of liquid” so we need to consider things like oils and solvents, though these will also have appeared in our Atmospheric section. And don’t just put lifejackets on the risk assessments, they won’t get out of the hatch with them on. Watch out for computer controlled equipment too, they can open and close valves without you realising.

On the subject of drowning, many confined spaces though not all, pose an intrinsic risk of falling and access equipment will often have to be used. In these situations the access equipment can have a secondary protection effect in relation to the drowning - it’s an interesting bonus.


The 1961 regulations required that an employer cooled the environment to a reasonable level, though guidance as to what that was varied. The new ACOP and Guidance require the employer to ensure the employee is not overcome by an increase in body temperature, this is a far more pragmatic approach allowing employers to use the wide variety of technology now available to them to control the hazard.

Cooling the environment will still be the preferred option, but in many places it’s simply not possible to cool the environment. Indeed in an incident a few years ago, an employee was killed by falling sections of a rotating kiln, simply because the employer allowed it to cool and the lining collapsed. The heat and expansion of the components had kept it together. Frequent breaks from the high temperatures, cool air supplied to the breathing zone and frequent small drinks (non-alcoholic) to maintain body fluid levels are the simplest and best control measures in these situations - just like on holiday.

Free flowing solids

Something that didn’t appear in the 1961 regulations but very relevant nonetheless. Particularly relevant to the agricultural industry, this term describes the effect of a material of a particulate nature that will flow over itself in exactly the same way as water, however when you look at it, it appears solid. A bit like the proverbial quicksand, the victim either sinks into the material and suffocates as the airway blocks, or the pressure of the material pushing on the chest prevents the lungs expanding and the victim asphyxiates.

The solution here is to prevent sinking into the material or making sure material cannot bury a victim from above. Another useful by-product of the fall arrest equipment is its ability to be locked off in one position preventing sinking, whilst a simple process of isolation or cleaning can prevent the ingress of materials from above.

Low, medium or high

A new aspect to the area of risk assessment for working in confined spaces comes from the work being done by the Sector Skills Councils in conjunction with the HSE. A drive to co-ordinate efforts into one scheme for workers in confined spaces has lead to a simple classification scheme. The scheme relies on the difference in dangers the employees are exposed to.

Low risk entry with adequate natural or mechanical ventilation. Access appears simple and unobstructed and there is no likely risk of flooding. Risks would be slight, there would be little chance of a rapid change in atmosphere, access equipment may be needed but the entry and exit would be relatively short in duration. A defining point would be the absence of breathing apparatus for escape or entry purposes. It may include situations of lone working

Medium risk entry will require the use of escape breathing apparatus. It will involve the presence of one or more people - positioned outside the confined space - who have designated responsibilities for controlling the entry and dealing with emergencies. A likelyhood of gas alerts or fall arrest situations occurring and where lone working is definitely not a possibility

High risk entry is about working in confined spaces which have non- standard entries which, as a consequence, make rescue difficult. It is likely that a hazard will be present at some time during the entry. Entry may involve complex entry procedures and there will be work-specific controls and rescue arrangements. It will entail the use of self-contained open circuit breathing apparatus, specialist detection equipment and resuscitation equipment. It will require the presence of personnel who have designated responsibilities for dealing with emergencies (see national occupational standards units for overseeing work in confined spaces or emergency rescue and recovery of casualties from confined spaces)


Told you I’d come back to it. Once you’ve decided on the nature of the confined space, its hazards and control measures, you can start to look at the skill sets required for working in your confined space. You’ve done the hard bit - the risk assessment, the safe working procedure, the permits where necessary - the only thing that can go wrong now is the people doing the work. And in the majority of cases that’s where it goes wrong.

There now exists a qualification, produced by City and Guilds, on behalf of the Sector Skills Councils with the support of the HSE, for each of the low, medium and high risk situations as described above. There is even a separate section for Overseers and Rescue Teams. Each of the qualifications can only be delivered by approved Registered Centers, who must meet strict performance criteria ensuring the quality of the product right down the line. These skills are highly transferable and can be mapped against other qualification schemes to ensure the employee has the necessary skills and abilities to deal with the confined space they are about to enter.

The practices may not have changed, neither has the equipment - ok it’s a bit more sophisticated now but it still does the same job - but the attitudes to Confined Space working has. It’s a lot more formalised, more definite in its requirements and more professional. Also the people working in confined spaces now have a professional qualification that is recognised by industry and the HSE alike.

I’ve tried to put a lot in this document about Confined Space working and ended up only scratching the surface. But if only one thing comes out of it, it should be that there is now the legislation to make working in Confined Spaces more practical, and the qualifications to prove it.

Published: 10th May 2009 in Health and Safety Middle East

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