The Ins and Outs of Confined Space

The Ins and Outs of Confined Space

Published by Safety Services, Inc. on Jul 27th 2023

What is a Confined Space?

If you have ever tried to fit your adult-sized body through a kid’s playground tunnel to rescue a fearful toddler, you understand the feeling of a confined space. A confined space is an area that is not necessarily meant for a person to enter, but out of need, a worker may find themselves in one. According to OSHA, a confined space must meet the following requirements:

  • large enough for an employee to enter and work
  • have a restricted or limited entry and exit
  • Is not designed to be occupied for a long period of time

That sounds a lot like the playground tunnel I referenced, except I have seen kids hole up in those for hours, so it might not qualify under the last point.

In all seriousness, confined spaces pose an immense danger to employees, especially when workers are not properly trained, and the area is not thoroughly evaluated. After analyzing worksite injuries, it was discovered in 2017 that each week two people will go to work and not return home because of entering a confined space. The best armor to defend against danger (except for confined space PPE of course) is knowledge, so join us as we explain all there is to know about confined spaces.

Types of Confined Spaces?

There are two types of confined spaces: non-permit required confined spaces and permit-required confined spaces. Non-permit required confined spaces are what was just described in the above paragraph. They must be large enough for entry, have limited access points, and are not designed for continuous occupancy.

Non-permit required confined spaces do not contain atmospheric hazards or serious safety dangers, but that does mean they are completely secure. For example, an attic could be deemed a non-permit required confined space, but a worker could still injure themselves by tripping on an obstacle or falling through unstable flooring. A few examples of non-permit required confined spaces include:

  • Storage bins
  • Underground vaults
  • Pipelines
  • Tanks
  • Reserve pits

Some confined spaces require a permit to enter, and these areas are appropriately referred to as permit-required confined spaces. A permit-required confined space meets all of the requirements of a non-permit required confined space, but according to OSHA, they also must contain at least one of the following characteristics:

  • “Contains or has a potential to contain a hazardous atmosphere
  • Contains a material that has the potential for engulfing an entrant
  • Has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor which slopes downward and tapers to a smaller cross-section

Contains any other recognized serious safety or health hazard"

Notice how unlike non-permit required confined spaces, where all three requirements must be met, only one of the above points has to be present for an area to be deemed a Permit required confined space. Some examples of permit-required confined spaces include:

  • Sewer manholes
  • Grain silos
  • Elevator Pits
  • Electrical Vaults
  • Air handling units

What are the hazards in a confined space?

According to the US Department of Labor, 92 workers die every year in confined space workplace incidents. It’s easy to assume that confined spaces are very small and that the biggest threat is becoming permanently trapped. While that is a concern, especially for miners or those that work in manholes, there is a multitude of other types of confined spaces that provide unique hazards of their own.

Fires and explosions

Oil and gas industry laborers commonly find themselves in confined spaces while working with explosive materials; talk about a high-pressure gig! Gas and well drillers put themselves at risk by leveling, trenching, and excavating sites that are filled with naturally combustible elements. Electricians frequently deal with intricate wiring systems in constricted areas.

Flammable substicances like gasoline and methane are more likely to ignite in confined spaces, and they can easily catch fire from metal friction, grinding, or welding sparks. If you can believe it, even dust is explosive! According to the Chemical Safety Board, between 1980 and 2005, there were 281 combustible dust explosions in the United States, which resulted in 199 deaths and 718 injuries. Dust is most likely to ignite in an enclosed area, which can make improperly ventilated confined spaces a literal ticking time bomb.


Engulfment results from a worker being overtaken by a granular material like grain or being immersed in a liquid. Depending on how much you like oatmeal, the thought of swimming in a sea of grain might not sound so bad, but don’t be fooled by the seeming innocence of your breakfast cereal. The weight of materials like grain or flour found in storage facilities is so dense that a person can easily be crushed.

Large amounts of fine substances, like sawdust, can cause suffocation by filling the lungs. According to an Agricultural Safety and Health report, “Agriculture ranks third, only behind the mining and oil and gas industries, in the number of documented fatalities occurring in confined spaces.” Suffocation in grain storage facilities and manure storage structures (what a way to go) are two of the most common causes of fatalities in the industry.

Hazardous gases

People in many fields face the added danger of toxic gases while working in confined spaces. It is imperative that technicians properly monitor the atmosphere of a confined space before entering it and while inside. For example, the bacteria in sewer systems can give off deadly levels of hydrogen sulfide, which can lead to unconsciousness and death within minutes. Carbon Monoxide is another common deadly gas found in confined spaces with vehicle exhaust being the usual culprit. Manure sotrage areas, which we already cited for their engulfment danger, also give off hazardous gases, including ammonia, carbon dioxide, hydrogen sulfide, and methane.

Extreme temperatures

Very high or low temperatures cause a risk in confined spaces. In residential construction, attics, basements, and crawl spaces are the most restrictive areas in the home, but because of the size and accessibility, they usually do not require a permit to enter. However, if you have ever gone up to the attic in the middle of the summer to search for 4th of July decorations, you know how unbearably hot the space can become. In that case, heat levels can trigger the need for a confined space permit and cause serious injury if not properly monitored. Conversely, Freon found in refrigeration spaces can replace oxygen, resulting in suffocation hazards.

When do you need a confined space permit?

While all confined spaces present the opportunity for danger, permit-required confined spaces have especially perilous characteristics. Before any work is done near a confined space, the supervisor and workers must evaluate the area to determine any potential risks. If the dangers can be eliminated, the confined space can be classified as not needing a permit. However, remember that for a confined space to require a permit, it only needs to meet one of the following requirements:

  • Contains or has the potential to contain a hazardous atmosphere (like toxic gases found in sewer manholes)
  • Includes a material that has the potential to engulf you (such as grain or flour in a storage structure)
  • Has an internal configuration that can trap you or cause asphyxiation by inwardly converging walls or by a floor that slopes downward and tapers to a smaller cross-section (like dust accumulators, hoppers, and silos)
  • Contain any other recognized serious safety or health hazard (such as a space that contains moving parts, sharp objects of dangerous materials)

Employer’s responsibilities of a permit-required confined space

If the confined space does require a permit, many steps need to be taken to ensure the safety of your workers.

Put up a sign

First of all, post a sign that notifies employees of the dangers of the space. Don’t just rely on a company email or meeting to inform your workers of an onsite hazard. For all you know, they’ve been filtering messages from you for years. The sign should say something like “Danger – Permit-Required Confined Space, Do Not Enter.” Make sure it is printed in a language that all employees can read.

Decide if workers will enter

If entry will be required, you can continue to the next step. If employees will not be entering the area, you must make it inaccessible to them by way of your choosing. Consider a lock or barricade. The last thing we need is Dan from accounting taking a massive fall because he wanted to see what an elevator shaft looked like up close.

Create a written program

Your company will need to create a Permit-required Confined Space Entry program that details its plan for protecting workers against on-site dangers and explain how entry to the area will be controlled. OSHA has many requirements for what the written program should cover, including testing atmospheric conditions, identifying job duties, and ensuring that at least one attendant is stationed outside the space during operations. It is recommended that the program is reviewed at least annually.

Prepare the permit

Before a worker accesses the confined space, an entry supervisor must confirm that the pre-entry checklist has been completed and sign off on the permit. The permit will contain the following information:

  • Confined space location and description
  • Date of entry
  • Purpose of entry
  • Time in and out
  • Permit canceled time
  • Reason for permit cancellation
  • A list of hazards found in the confined space
  • Special requirements
  • Special equipment
  • Levels of atmospheric hazards
  • Atmospheric hazards testing times
  • The names of those who performed atmospheric tests
  • Test instruments used
  • Authorized entrants
  • Authorized attendants

Provide training

Before entry, any worker who is required into the confined space must be properly trained on how to minimize risks, handle the hazards, and safely perform their job duties. Team members who will perform necessary rescues must be trained in CPR and first aid.

Perform additional training if any of the below occur:

  • A change in job duties
  • The discovery of a new hazard
  • A change in the permit entry program
  • An employee seems to lack the skills and knowledge to enter the permit-required confined space

Employee Tips

Any employee who is required to enter a permit-required confined space has the right to be properly trained and offered acceptable PPE. If you will be working in a confined space, consider the following recommendations to stay safe:

  • Do not enter a permit-required confined space without completing the pre-entry checklist, having a properly filled-out permit, or being properly trained.
  • Understand how to enter and exit the confined space and go over all employee procedures.
  • Before you enter, determine any physical hazards.
  • Test the atmosphere for oxygen content and toxic gases and monitor explosive hazards before entry and while inside.
  • Use all of the personal protective equipment that your employer has provided to you.
  • Remember the buddy system. Remain in contact at all times with a trained attendant so that they can quickly perform a rescue if needed.

OSHA has created a handy, quick guide that lays out the above safety points and details what constitutes a permit-required confined space.

We’ve got your back

With the right tools, confined spaces can go from potentially dangerous to just annoyingly cramped. Safety Services Inc. offers gear that combats every hazard encountered in the field, including air monitor gas detectors, tripods, and harnesses, among many others. View our website to see all of our confined spaces offerings.