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Enclosed Spaces

There is always a risk of accidents in jobs done in enclosed spaces. An accident occurring in a space that is difficult to get out of or difficult to get into for rescue operations creates stress. By conducting a thorough risk assessment, using the right equipment and establishing a rescue plan, you reduce the risk of both accidents and unnecessary poor decisions.

Active protection when working in enclosed spaces

The following provide a good foundation for protecting yourself in enclosed spaces:

Measure the oxygen level
There is always a risk that the oxygen level may be too low. The oxygen level should therefore be measured before entering. Too low an oxygen level can cause loss of consciousness and death.

Measure the gas level
If there are explosive gases in the area, these could cause an explosion. This may be solvent residues or gases from a decay process. The highly toxic gas hydrogen sulfide can also result from the process of decay.

Have the right equipment
Always measure the above gases with a gas detector before entering the space. Carry the detector with you into the space. Reduce the risk of accidents by using a respirator adapted to the situation. Also dress in appropriate workwear and use safety equipment adapted to the environment in which you will be working.

What is an enclosed space?

An enclosed space often has limited access points and is difficult to get in and out of. In many cases, ventilation is limited, sometimes lacking completely. Such spaces are not suitable for prolonged work.


Examples of enclosed spaces

Silos, wells, cold rooms, cisterns, tanks, containers and cargo areas.

Industries commonly at risk

  • Farming and agriculture
  • Food processing
  • Chemical industry
  • Water treatment
  • Waste management
  • Transport
  • Real estate

What are the risks of working in enclosed spaces?

Oxygen deficiency, fire and explosion are some of the risks for jobs in these environments. There is also a risk of falls and other accidents.

  • Oxygen deficiency. If the oxygen in the air be depleted or replaced by toxic gases, you may experience headaches and loss of consciousness. In the worst case, your life could be in danger.
  • Fire and explosion. Due to the release of gases, excessively high heat and electrical faults, there is a high risk of both fire and explosion.
  • Falls. Improperly handled personal safety equipment, combined with high altitudes can lead to falls.
  • Drowning in cases where water levels suddenly rise.
  • Hearing damage caused by loud noises amplified in the space.
  • Unpredictable risks. In confined and enclosed spaces, an incident could lead to unwise decisions being made due to panic.

How to protect yourself against accidents in enclosed spaces

Check the air before starting work

A risk assessment must always be performed before starting work in enclosed spaces. Only commence work when you are sure that the oxygen content inside the enclosed space is sufficient, that there is no hazardous gas and that there is no risk of explosion. It is important to think about the type of mask you are using, a half mask, a fresh-air fan-assisted full mask or a compressed air-fed mask. Bear in mind that beards can cause the mask to leak.

The risk assessment may involve:

  • Measuring the oxygen content to check that it is sufficient. If the oxygen content is too low, unconsciousness quickly follows. Several deaths have occurred this way. If there is a risk of low oxygen content, the oxygen content must be measured before starting work.
  • If there is a risk that the area contains residues or vapors of flammable or explosive substances, take measurements to ensure that there is no risk of explosion (unless it is evident that the concentrations are so low that there is absolutely no risk of explosion).
  • Measure for hazardous gas, such as hydrogen sulfide or carbon monoxide, that may be present in the area.
  • Instead of measuring, you can ventilate the space well for several hours before starting work. In such cases, you must ensure effective airing (just opening a hatch is usually not sufficient).

Measuring the risk of explosion

  • The risk of explosion is measured with an explosimeter. Check that the explosimeter is Ex-certified, and can be used in the type of spaces in which it is intended to be used (depending on the gases or vapors present and the area).
  • The oxygen content must also be measured when measuring the risk of explosion, as the risk of explosion is underestimated if the oxygen content is lower than normal.
  • For work that does not entail heat nor anything that can act as an ignition source, 25% of the lower explosion limit must not be exceeded (if the oxygen content is 21%).
  • During hot work, 5% of the lower explosion limit must not be exceeded (at 21% oxygen content).

Establish a rescue and evacuation plan

Accidents in enclosed spaces are stressful. It is necessary to have clear procedures and adapted measures detailing what should be done in the event of an accident. Before work commences, a clear description in bullet points of what to do in the event of an accident must always be drawn up.

What does the law say? What is the employer’s responsibility?

The law states: AFS 2011:19 Chemical Hazards in the Working Environment The Swedish Work Environment Authority’s regulations and general advice on chemical work environment risks.
When an investigation and risk assessment shall be conducted Section 5 The risk of chemical hazards causing ill-health and accidents in the activity shall be investigated and assessed in accordance with Sections 6–9 as often as the conditions of the activity demands it. Furthermore, such an investigation and risk assessment shall always be conducted when the activity is temporarily or permanently changed or if it can be expected that the result of the risk assessment will be affected due to new information. The air shall be examined and assessed every time work is to be commenced in a cistern, well, silo, loading space or similar. If it is not obvious that the air is safe, the air’s content of oxygen and substances hazardous to health shall be measured and the risk of explosion shall be assessed by measuring the percentage of flammable gases and fumes. Work may not commence before an investigation and risk assessment have been conducted and necessary measures have been taken in order to prevent ill-health and accidents at work.
Work in cisterns, wells, silos, loading spaces or similar Section 31 Before commencing work in a cistern, well, silo, loading space or similar, a special risk assessment shall be performed in accordance with Section 5, third paragraph. When implementing Sections 8 and 9, it shall be assessed whether the air needs to be continually monitored throughout the work. If the space cannot be ventilated so that the composition of the air becomes safe, suitable respiratory protection shall be used.


Employer’s responsibility: AFS 2015:4 Organisational and social work environment. The regulations on the organizational and social work environment state as follows: Section 5
Section 5 The Swedish Work Authority’s provisions on systematic work environment management contain rules concerning work environment policy and knowledge requirements, and also require the employer to regularly investigate and assess what risks may arise at work. The provisions also include regulations requiring the employer to take corrective measures to manage risks. According to the Swedish Work Environment Act, the employer has a work environment obligation to take all measures necessary to prevent and reduce ill-health and accidents. This is far-reaching responsibility. The requirement for measures varies depending on the type of activity the employer conducts. Specifically, the employer is obliged to remain up-to-date and to conduct active systematic work environment management.

This entails:

  • Researching
  • Assessing risks (in writing)
  • Taking action as required
  • Checking and continuously evaluating the above

As an employer, it is important that you stay up-to-date, involve health and safety representatives or work environment representatives, and keep employees informed and updated about how you assess the situation.

Other risk areas

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