Confined Space Meaning & Definition | EcoOnline US
Health & Safety Glossary

Confined Space

Confined space refers to enclosed areas with limited access, posing potential hazards.


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What is a Confined Space?

worker in confined spaceA confined space is any space that offers limited entry and exit points, and is generally not designed to accommodate humans. For instance, a common example of a confined space is the inside of a storage tank. Maintenance workers generally enter such tanks through narrow openings, and egress through the same.

Confined spaces aren't designed to be occupied by humans for longer periods of time, and there is an increased risk of inhaling harmful gases or dust clouds, or asphyxiating in such spaces. Those who suffer from claustrophobia must also take special care to avoid such spaces.


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How to Determine a Confined Space

In general, there are specific criteria that determine if any space can be categorized as "confined." These are listed as follows:

  1. Limited entry or exit opening: Confined spaces are generally difficult to enter, and provide limited space for exits. Maintenance crew must take proper care when entering such spaces, because in case something goes wrong, escaping from a confined space is generally difficult. An example of this is a tank with a singular opening. 
  2. More importantly, confined spaces are designed to be occupied by humans. These are spaces that are created for a specific purpose, and aren't suitable for humans. 
  3. Furthermore, a confined space must be large enough that it allows a person to enter and complete their work. Otherwise, there is a significant risk of getting trapped within the space. 

As per the guidelines provided by the Occupational Safety and Health Administration (OSHA), all confined spaces must meet these three criteria to be classified as such. 

In most cases, confined spaces pose serious risks due to the hazards present. These can include exposure to hazardous materials, high temperature, free-flowing solids or liquids, harmful vapours or gases, or flammable chemicals. 


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Hazards Associated with Confined Spaces

There are several hazards that workers and maintenance crew must be aware of before they venture into confined spaces. Some of the many hazards associated with confined spaces are listed below. 

Toxic Conditions

The atmosphere within a confined space can be toxic, which means it could result in serious acute effects. If a person is exposed to such toxicity due to the presence of hazardous substances within a confined space, it could result in a fatal illness. 


In most situations, confined spaces are generally very narrow, thus reducing the space available for air to move around. They are also not properly vented, which further affects the displacement of air. A lack of oxygen within a confined space could eventually result in asphyxiation.

There are other things that can result in an oxygen-deficient environment as well. Biological processes, such as rusting metals, rotting organic matter or waste, or a fire that could reduce the oxygen in the environment. 

Flammable Atmosphere

The atmosphere within the confined space could also be flammable, thus increasing the risk of an explosion or a fire. For instance, if flammable liquids are present within the confined space, it is important to take appropriate steps for the maintenance crew or people entering the confined space to protect themselves.

An explosion within a confined space, even a small one, could result in hot gases being expelled into the area, and could also affect the integrity of the structure, increasing the risk of injury.

Free-Flowing Liquids and Solids

Free-flowing solids or liquids within a confined area could increase the risk of burns, suffocation, or drowning. Solids, found in powdered form, could also create an atmosphere where people experience difficulty in breathing, increasing the risk of asphyxiation.


Because confined spaces are generally enclosed, they are able to retain heat much longer. As a result, excessive heat within a confined space could also result in injuries to people within the space. The risk is likely to increase if proper steps are not taken to protect against the hazard.

Taking Steps to Mitigate Hazards in Confined Spaces

It's common knowledge that confined spaces are generally more hazardous than open ones. The margin for error is considerably low, and if the hazards aren't correctly identified, it could result in serious consequences for the maintenance crew. 

As a result, it's important for companies to conduct a thorough risk analysis to identify the risks and the hazards present in the confined space. It's also important to factor in the circumstances, and any variables that might come with a change in the conditions. 

Then, a thorough plan should be created to ensure the safety of the risks after all risks have been identified. The plan should also include steps taken by the company to mitigate or eliminate any risks within the confined space.


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