Last update: 5/03/2024

Working in a confined space is associated with considerable risks. It involves narrow spaces with limited air circulation, narrow passageways and extra risks.

These spaces are often difficult to access, with limited exit options and can also contain a hazardous atmosphere.

In this article, we provide more info around the dangers posed by confined spaces and which measures must be taken in order to work safely.

The definition of a confined space

A space is confined if it is not designed for long periods of work, has enclosed characteristics, with a potentially hazardous atmosphere and is difficult to access. A hazardous atmosphere means an atmosphere that could give rise to intoxication, asphyxiation and fire or explosion.

A confined space, in other words, is a workplace that is difficult to access and which is not usually intended to be used by people. Nevertheless, it is sometimes necessary to access these spaces for repairs, maintenance, cleaning or inspection.

Examples of confined spaces include tunnels, wells, pipelines, sewers, crawl spaces, safes, bunkers, inspection and construction wells, loading or fuel tanks on ships, silos and other storage tanks.

Confined spaces can be both above and below ground and have restricted entry/exit points and limited evacuation options. As a result, you cannot escape the space easily and may be confronted with various risks.

If you are unsure of whether the space should be defined as confined, you are advised to assume that it is.

8 hazards when entering a confined space

When you need to enter a confined space, it is important to consider the (often invisible) risks of this space.

The most common problems are set out below.

#1: Asphyxiation

The primary hazard in a confined space is asphyxiation. This occurs when the oxygen concentration is below 19%. The dangerous thing is that your senses do not perceive this. You become unconscious and fail to recognise the dangers.

Risks of reduced oxygen level:

• Insufficient ventilation can lead to an oxygen deficiency, caused by chemical or biological reactions. For example, gases released from paint drying or from poorly sealed pipes displace the oxygen.

• Some welding processes also involve hazardous gases. If you cannot evacuate these gases, they form a hazard.
• The presence of inert gases such as nitrogen or carbon dioxide also cause oxygen deficiency. In some cases, you can prevent fire or explosion hazards in this way, i.e. by keeping the level of air low.

#2: Fire and explosion risk

If the oxygen concentration is higher than 21% OR 23.5%, there is a risk of fire or explosion. In a confined space, where the oxygen concentration is 30%, for example, one spark is enough to burn cotton overalls within a minute.

One of the most common causes of an excessive concentration of oxygen is incorrect use of welding or cutting equipment. Flammable and explosive substances that can be present in confined spaces include paints, solvents, (residues of) materials and cleaning rags, gas or oxygen escaping from badly sealed gas and oxygen cylinders, or from the leftover contents in the confined space itself. Ignition can take place due to the discharge of static electricity or using tools that are not antistatic. With gas detection equipment detect hazardous fumes and gases before and during entry into the confined space.

#3: Poisoning/hazardous gases

The symptoms of poisoning occur in the event of exposure to hazardous substances. These effects may be evident immediately after exposure but may sometimes only become clear after some time. These hazardous substances infiltrate your body through your lungs, mouth or skin. Exposure to detergents, paintwork, electrical welding or work on contaminated soil can lead to the release of dangerous substances or gases. Om je te beschermen tegen het inademen van schadelijke stoffen is het belangrijk goede adembescherming te dragen.

#4: Electrocution

Electrocution occurs when you touch objects carrying electric voltage. The risk of electrocution is high when electrical tools or cables are damaged, e.g. by pinching. And when damaged cables make contact with the metal parts or walls of a confined space, those also become live.

#5: Heat stress

Heat stress occurs when you are no longer able to regulate your own body temperature due to high temperatures and air humidity. The causes of this can vary but include radiated heat, humidity, or wearing protective clothing such as gas suits. This can lead to ‘heat sickness’ such as heat exhaustion or heat cramp. In environments with extreme heat, such as engine compartments, it is vital to drink adequate water to compensate for transpiration, preferably every 15 to 20 minutes. Cooling vests are ideal for preventing heat stress.

#6: Becoming trapped

In confined spaces, the access openings are often very narrow and it may be difficult to get in and out. It is possible to become trapped, due to:

• Narrow entrances and exits
• Limited space in the work area
• Transport of materials
• Use of special PPE, such as gas-tight overalls, that take up a lot of space but are crucial.

#7: Noise

Equipment such as compressed air tools or welding machines generate a lot of noise. Because of the high resonance (sound reverberation) in a confined space, the noise quickly exceeds 80 decibels. Good hearing protection is therefore essential when working in a confined space. So good hearing protection is definitely in order when working in confined spaces.

#8: Tripping and falling

You may need to work at height because access to the confined space is also located at height. Racks or ladders are regularly used inside the space. Wearing fall protection and a safety helmet specifically for working at height is therefore crucial when entering a confined space.

When work takes place on different levels, there is a risk that tools, loose objects or rubble could fall. Wearing a helmet is vital in order to protect yourself from falling objects.

Also read: How do you inspect your fall protection harness?

How should you enter a confined space?

Safely entering a confined space requires careful planning and the implementation of various safety measures. Both organisational and practical aspects must be considered to keep risks to a minimum and guarantee the safety of all those concerned.

Organisational

From an organisational point of view, a thorough risk analysis is vital before entering the space:

• A detailed risk inventory and evaluation of all possible hazards in the relevant confined space
• Special attention to specific tasks which relate to additional hazards or which worsen existing hazards, such as welding, cutting, burning, painting, gluing and electro-technical works.
• Regular measurements to check the atmospheric conditions are vital to identify hazardous situations quickly.

It is also vitally important to apply all protocols and train all concerned individuals. Every team member must be aware of his/her role and responsibilities and a detailed work permit must be issued and signed by all parties each time the space is accessed. Regular training on risks, the correct use of equipment and emergency situation procedures also helps to maintain increased awareness and reduce the risk of incidents.

Practical

In practical terms, various measures must be taken before the space is accessed. This means disconnecting and locking all possible sources of influence on the conditions within the space, adequately ventilating the area to remove hazardous substances and maintain oxygen levels, and conducting measurements to check the availability of hazardous substances.

Communication between those entering the space and the supervisor(s) is essential; various methods, including banging signals, walkie-talkies or mobile telephones can be used. The use of non-explosive electrical equipment and the provision of emergency lighting and extinguishers is also crucial to ensure a rapid and effective response to any emergencies.

Working in confined spaces for long periods should also be avoided. If you must enter a confined space as there is no other solution, make sure that as many preparations as possible take place outside the confined space so that the time spent inside is as short as possible.

A summary:

• Draw up a risk analysis
• Make the necessary preparations and provide the appropriate equipment
• Keep the duration as short as possible
• Provide constant supervision and be alert at all times
• Provide training to all persons concerned

Personal Protective Equipment for safe working in confined spaces

As well as the above measures, it is vital to use the appropriate Personal Protective Equipment (PPE) to ensure all risks in the specific working situations are prevented. The choice of PPE is determined by the Risk Inventory and Evaluation (RI&E), whereby the risks are reviewed along with the seriousness of the hazards.

When working in confined spaces, you might think of: respiratory protection to ensure oxygen supply, protection from hazardous substances, wearing a safety helmet to prevent injury from falling objects, and using chemical suits to minimise exposure to harmful materials.

PPE for:

Entering and leaving a confined space

• Gas detectors: use gas detectors to detect hazardous fumes and gases before and while entering the confined space.
• Barricade material: with barricade material you create a visual workplace and cordon off the area around the confined space entrance.
• Lock Out Tag Out: thanks to LoTo locking systems, you avoid accidental opening of pipes.
• Fall protection:
  • Exofit Rescue 2-point harness with spreader: this rescue harness is easy to put on and is comfortable and safe. With a unique revolver system, anti-trauma straps and quick closures. The 2 hooks on the shoulder straps make it ideal for rescue from enclosed spaces (victim comes straight up), in combination with rescue harness spreader.
  • AM100 tripod with accessories: AM 1 tripod with tubular aluminium legs for lowest possible weight. The four eye bolts in the head can be used as anchor points. Adjustable from 1.35 to 2.35 metres and calculated on 2 persons, who can have a combined weight of 500kg. You can also use the accessories.
    • AT200 winch (20 metres)
    • Rebel fall arrest block (15 metres)
    • Rebel fall arrest block in Stainless steel (15 metres)
    • Adapter to mount Rebel fall-block on leg of AM100 tripod
    • AT052 pulley
  • Davit Arm large and small: Davit Arm in 5 parts is the ultimate solution for lifting and safety. With an adjustable mast, lightweight design and simple winch installation.  A universal anchor point and supple cable guide for unparalleled versatility and safe access to confined spaces. We offer both a large Davit Arm and a small Davit arm.
  • Rollgliss rope (30 metres): Rollgliss lowering/evacuation set with 30 metre length of a 9 mm kernmantle rope. Descent/evacuation Rollgliss can be hung from the eyes of the Rollgliss tripod or using another anchor point. Equipped with a 3:1 reduction, which makes it easier to raise and lower the load.

Working safely in confined spaces

• Respiratory protection
  • Spasciani set SK 1203: This escape hood with compressed air provides ultimate protection in confined spaces for 15 minutes. With integrated half-face mask and automatic activation upon opening. Weighs just 6 kg.
  • Compressed air device from MSA: the M1 Pro Single Line and the Compact M1 are compressed air devices that provide respiratory air and overpressure in the full-face mask regardless of the environment. The M1 has an ergonomic backplate for a maximum of 2 bottles with shoulder and hip straps with comfort pads. The Compact M1 has a basic backplate for a maximum of 1 bottle with shoulder and hip straps without comfort pads, with plastic closures.
  • Spasciani 1043498 compressed air: a compressed air trolley with 2 bottles of 6L with 300 bar and a 50 m hose on a reel.
• Gas detectors: use these gas detectors to detect dangerous fumes and gases while entering the confined space.
• Cooling vests: wear a cooling vest to prevent heat stress when entering a confined space.
• Chemical clothing: disposable or reusable chemical coveralls protect your body when at risk from hazardous liquids or vapours.
• Safety helmet: this lightweight safety helmet and ventilated safety helmet, both made of strong ABS, offer a high level of protection when entering a confined space.

Rescue from a confined space

• Fall protection:
  • Exofit Rescue 2-point harness with spreader: this rescue harness is easy to put on and is comfortable and safe. With a unique revolver system, anti-trauma straps and quick closures. The 2 hooks on the shoulder straps make it ideal for rescue from enclosed spaces (victim comes straight up), in combination with rescue harness spreader.
  • AM100 tripod with accessories: AM 1 tripod with tubular aluminium legs for lowest possible weight. The four eye bolts in the head can be used as anchor points. Adjustable from 1.35 to 2.35 metres and calculated on 2 persons, who can have a combined weight of 500kg. You can also use the accessories.
    • AT200 winch (20 metres)
    • Rebel fall arrest block (15 metres)
    • Rebel fall arrest block in Stainless steel (15 metres)
    • Adapter to mount Rebel fall-block on leg of AM100 tripod
    • AT052 pulley
  • Davit Arm large and small: Davit Arm in 5 parts is the ultimate solution for lifting and safety. With an adjustable mast, lightweight design and simple winch installation.  A universal anchor point and supple cable guide for unparalleled versatility and safe access to confined spaces. We offer both a large Davit Arm and a small Davit arm.
  • Rollgliss rope (30 metres): Rollgliss lowering/evacuation set with 30 metre length of a 9 mm kernmantle rope. Descent/evacuation Rollgliss can be hung from the eyes of the Rollgliss tripod or using another anchor point. Equipped with a 3:1 reduction, which makes it easier to raise and lower the load.

Legislation on confined spaces

Accidents occur regularly because employers do not correctly assess the risks in such spaces. Strangely enough, Belgian legislation does not provide a definition or specific legislation on how to safely enter a confined space, simply instructions (Source: Prebes). There are clear guidelines and instructions in the Netherlands and France.

For Belgium (Codex):

• The Belgian Codex addresses this issue, as can be seen in 7c(1) and (2). So there is a small degree of regulation, but the wording is vague.

For the Netherlands (Arbowet, Arbobesluit, Arboregeling):

• The Health & Safety decree (Arbobesluit) Article 3.5g risk of asphyxiation, 3.5h safety of tankers, 3.6 evacuation routes and emergency exits, 3.7 safe use of evacuation routes, 4.6 preventing undesirable events, 8.2 choice of PPE, 8.3 availability of PPE
• Health & Safety regulation (Arboregeling) paragraph 4 Safety on or in tankers

For France:

• “Les espaces confinés” INRS ED967 July 2006
• “Cuves et réservoirs”, Recommandation CNAM, R 276
• “Pas de vie sans oxygène”, ED 632
• “Ventilation des espaces confinés”, ED 703
• “Moteurs diesel et pollution en espace confiné”, ND 2239