Dear Richard,

The following are particular examples of what is, in practice, meant by a confined space. These would included vessels, tanks, containers, vats, silos, hoppers, pits, bunded enclosures, trenches, pipes, sewers, flues, wells, chambers, compartments, cellars or other similar enclosures. Occasional confined spaces are also mentioned as being within the scope of Confined Space Regulations, such as a paint spraying booth or a metal duct undergoing a welding operation, or an area that becomes a confined space by reason of coincidence such as an unventilated pub cellar and a leaking gas cylinder.

When workers enter what are formally defined as "confined spaces" they are potentially at risk because of the enclosed nature of the spaces. A confined space is defined in law:

"as any place which, by virtue of its enclosed nature creates conditions which give rise to the likelihood of an accident, harm or injury of such a nature as to requiring emergency action due to:

(a) The presence or the reasonably foreseeable presence of:

(i) Flammable or explosive atmosphere;
(ii) Harmful gas, fume or vapour;
(iii) Free flowing solid or an increasing level of liquid;
(iv) Excess of oxygen;

(b) Lack or reasonably foreseeable lack of oxygen".

It is worth noting that some places may become confined spaces when work is carried out during construction, fabrication, maintenance or subsequent modification. Confined spaces would include:

(a) A construction that becomes a confined space during its manufacture, e.g. a gas or liquid storage tank which a worker has to enter to carry out welding or shot blasting when it is being fabricated;

(b) A paint spray booth or room whilst spray painting is being carried out;

(c) A reel oven or baking tunnel when it has to be entered for maintenance or cleaning.

The key characteristics of a confined space are described as being:

1. Substantially enclosed.
2. Having at least one of the hazards as defined in para. 1:1 above occurring within the space.
3. A risk of injury arising from one or more of these hazards.
4. The injury being serious enough to require an emergency rescue.

Examples of types of injury include:

1. An injury from a fire or explosion.
2. Loss of consciousness or asphyxiation from harmful substances or the lack of oxygen.
3. Drowning due to an increased liquid level.
4. Loss of consciousness due to an increase in body temperature.

The code requires that a proper audit is carried out in the workplace of all areas that may become a confined space, taking into account less obvious areas such as bunded areas, trenches, inadequately ventilated rooms, pub cellars, etc. including areas that may become confined spaces in a transitionary manner.

Hazards of Confined Spaces

This describes the various hazards present in a confined space, which may cause injury as a result of the enclosed nature of the space. These are the hazards that must be risk assessed with regard to Confined Space. It is true to say, however, that there are a variety of other hazards present in a confined space that are not concerned with the enclosed nature of the space. Such hazards may relate to tripping hazards, the exposure to micro-organisms in a sewer, vibration arising from the use of power tools to de-scale the tank. These hazards need also to be risk assessed.

Responsibilities

It is the duty of every employer to comply with these Regulations for both his employees and other persons who are not his employees for which he has control over matters relating to these Regulations. Employees shall co-operate with safety measures in Confined Space, in particular the use of work equipment and PPE.

Risk assessment

Confined spaces shall not be entered unless absolutely necessary. All alternative methods of carrying out the work need to be considered without the need to enter the space and if reasonably practicable the work should be carried out in this way. Designers of work places need also to avoid the creation of such spaces where possible.

Prior to entry, all risks must be assessed by a competent person and a safe system of work established and persons entering the confined space are provided with adequate information instruction and training for the work activity. A means of preventing unauthorised entry must also be established through the use effective controls, security measures and appropriate signage.

These risks need to be assessed on an ongoing periodic basis or as the need arises.

It must be remembered that there are many different types of confined space, for instance, for safety management purposes, a confined space could be defined as:

(a) Relatively large areas where unusual or hazardous operations are carried on or where access and egress is difficult;

(b) Areas where there is the potential for flooding, e.g. in drains or sewers;

(c) Areas where there may be movement of materials such as grains in large silos.

Significant hazards

Hazards can be considered in two ways: those which exist prior to work commencing, e.g. rusted pipes, depleting oxygen levels, and hazards which arise during the work.

Hazards, which exist prior to work commencing

The main hazards that make confined spaces potentially dangerous are:

• Fire or explosion
• Being overcome by gas, fumes or lack of oxygen
• Being overcome by an inflow of liquid or solid
• Being overcome by extremes of heat or cold.

These hazards are discussed in more detail below.

Fire and explosion

Fire or explosions in confined spaces can be extremely hazardous. Fire can be caused by combinations of gases or excessively high levels of oxygen being ignited by welding operations, for example. High levels of dust in the enclosed atmosphere can lead to explosions. These are particularly hazardous where means of escape is limited, e.g. narrow exit and entry routes which will only allow one worker to exit at a time and who's progress may be hampered by respiratory and protective equipment such as breathing apparatus.

Gas, fumes and lack of oxygen

Toxic gases such as hydrogen sulphide can be generated in enclosed atmospheres such as sewers. Entering rusty pipework can expose workers to risk of lack of oxygen. Entering vats that have been cleaned with solvents can cause the worker to pass out and die.

All these incidents have actually occurred and caused injury and death to workers. 

Inflows of liquids or solids

Workers who enter confined spaces such as grain silos could displace materials which, in turn, may move and cause them to become trapped and may result in death by asphyxiation. Work in underground drains, where there is the possibility of flooding, can also pose a hazard. Workers who use solvents, materials or compressed air during maintenance or cleaning activities can cause materials to move into the space where work is being carried out due to their work activities.

Extremes of heat or cold

Workers in confined spaces may have to wear protective equipment and carry breathing apparatus. Such equipment can be heavy and, if the ventilation in the underground space, chamber, excavation, etc. is poor, they may be operating in extremely hot and uncomfortable conditions. This can cause great stress or strain to the worker and if the circumstances are excessive enough, the worker may pass out and have to be rescued thus putting the rescuer at risk.

In addition, excessively hot claustrophobic atmospheres could cause the worker to panic and fail to react properly in case of emergency evacuation or procedures.

Extremes of cold can also mean the risk of injury is increased. If the space is such that movements are restricted and cramped this could restrict blood circulation possibly causing frost bite or even hypothermia.

Work in extremes of temperature whether hot or cold will tend to have an adverse effect on worker's judgement, co-ordination and speed of reactions.

Other hazards from work in confined spaces

(a) Lighting: The quality of lighting in confined spaces is very often far from ideal. Glare from high intensity lamps, areas which are veiled by shadow and poorly illuminated areas or corners, are all sources of potential hazard depending on the activity taking place and at the very least can cause strain and discomfort to the workers. Lamps used will generally be suitable for use in flammable atmospheres.

(b) Heavy loads: Having to wear heavy protective clothing or carry equipment can cause physical strain and fatigue. In addition, if the clothing is bulky, the worker's dexterity and ability to move comfortably, freely and quickly will all be restrained.

If such clothing must be worn, then it can increase hazards especially if the entrance or exit to the confined area is narrow.

(c) Noise, Another potential hazard to consider is noise. This can be caused by use of cleaning or maintenance equipment or perhaps by the effects of reverberation. Not only can this expose workers ears to excessive levels of noise which can have a long term effect on hearing but it could also interfere with the reception of warning signals or sounds (see Module on Noise).

Hazards arising during work

Hazards arising during work can result from both or either the use of substances and/or the use of equipment.

Use of substances

Hazards arising during work involving the use of substances can include:

(a) hazards arising from the operations carried out, e.g. use of paint or adhesives, welding fumes;

(b) ingress of gases, liquids or free-flowing solids such as grain, flour or sugar from adjacent plant which has not been effectively isolated.

Use of equipment

Hazards arising during work from use of equipment can include equipment used within the confined space or external to the confined space:

(a) within the confined space:

•  Electrical hazards arising from the use of welding sets, lighting or other portable Electrical equipment;

• Oxygen depletion caused by burning, welding or grinding;

(b) external to the confined space:

·         Introduction of exhaust fumes into the confined space from the use of mobile plants;

·         Introduction of ignition sources into the adjacent area where there might be flammable or combustible materials.

In addition, the worker will be put in danger if safety equipment is provided which is insufficient, inappropriate or faulty or where insufficient training has been given in its safe and proper use.

Who is at risk?

Persons at risk are not only employees working in the confined space but those in the vicinity, whether other employees involved in the task (especially likely to attempt rescue during an emergency and therefore at greater risk), persons working there temporarily or visitors to this area. Visitors to the area could include other employees visiting the area on company business or passing through, customers, or HSA and local fire brigade officials or rescue services personnel. Persons working there temporarily could include contractors, cleaners, agency staff, etc. There may also be occasions when a single person may be alone on the premises, e.g. a night security person who could possibly fall into a confined space/manhole that was not properly cordoned off or sign posted for example.

Safe system of work 

The results of the risk assessment will be used to determine a safe system of work. Examples of elements of the safe system of work are illustrated in  Figure 3. The Code places particular emphasis on the instruction and training of people who are required to enter confined spaces and the use of a permit to work system, and the establishment of a means of communication with those outside the confined space.

Regards,
Paul