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Confined Space Assessment: Factors to Consider and Precautions to Implement

Using a standard confined space assessment form will protect employees’ safety and ensure compliance with safety regulations while working. Learn about the most common hazards and find out how to write a checklist that meets the needs of your individual job site. Try it for free with Lumiform!

What is Confined Space Assessment?

A confined space assessment is a form of risk assessment used on confined workspaces. Confined workspaces are defined as areas that are substantially enclosed which have risks that can cause death or serious injury to workers.

When working in confined spaces, workers are faced with various risks such as asphyxiation, drowning, noxious fumes, and fire. And with limited access points, quick evacuation and rescue operations might not be possible.

That is why various institutions in charge of workers’ health and safety advise not to work in confined spaces as much as possible. And if it’s unavoidable, it is required to put safety measures in place to reduce the risks involved. Examples of confined working spaces are sewers, vats, ductworks, storage tanks, silos, and vessels.

Confined spaces have been deemed as a major hazard due to the number of casualties it causes annually. According to the U.S. Bureau of Labor Statistics (BLS), confined spaces have causes 166 deaths in 2017. And what’s scary about this number is that a large percentage of these casualties are from the would-be rescuers.

This is why many laws and standards have been put into place to reduce casualties from working in confined spaces. And violation of these laws will result in penalties that can cost up to hundreds of thousands of dollars.

In this short guide, we will be using the Confined Spaces Regulation of the United Kingdom’s Health and Safety Executive (HSE) as a reference for compliance.

In this article, the following points are explained:

1. What to include in a confined space hazard checklist

2. Precautions to take when working in a confined space

3. Benefits of using a digital checklist for confined spaces

construction worker working in the confined space of a sewer

What are the Factors to Consider in the Confined Space Checklist Hazard Assessment?

Before deciding to proceed with working in a confined space and setting up precautions, it is recommended by the Health and Safety Executive (HSE) to evaluate the confined workplace. Below are three essential factors to consider according to the confined space checklist hazard assessment.

General Condition of the Workplace

The general condition of the workplace refers to identifying present elements in the confined space that might cause problems to those who’ll be assigned to work in it. This involves going through records to get relevant information about the inspected space.

One of the elements to check is the previous contents held in the confined space. Knowing the substances that were previously held in the confined space will provide a good reference on what hazards to expect and what precautions to take.

It is also recommended by the confined space assessment form to check for residues of chemical substances, rust, scales, and sludge. This is critical because some of these residues can release dangerous gases that can poison workers.

Another element to consider is contamination from surrounding soil or adjacent plants. Fluids from these may infiltrate the confined space and contaminate the air. For example, groundwater with a high level of acidity may react to certain minerals and create a large volume of carbon dioxide.

The oxygen level of a confined space should also be checked before work gets started. And this is because oxygen levels that are greatly higher or lower than the ideal 21% will cause problems. High levels of oxygen increase the flammability of objects while low levels cause mental impairment and respiratory problems.

And the last consideration is the structure of the confined spaces. Differing ground levels and isolated ground pockets cause inconsistent air quality which can cause hazards to workers.

Hazards from the Nature of Work

The next factor to consider according to the confined space assessment form is the nature of work that will be done inside the confined space. Certain activities might affect air quality or have dangerous reactions with the residue or materials inside the space.

The first listed work that is hazardous in nature is the use of cleaning chemicals inside the confined space. Cleaning chemicals produces dangerous fumes that might accumulate inside the space if not ventilated properly. Some cleaning agents might have unwanted chemical reactions with residues inside the space that can produce noxious fumes, fire, and even explosions.

Next on the assessment form are works that can be sources of ignition. A primary example of this is welding. Sparks from welding can ignite flammable gases and materials that are used inside the confined space. And fire in a confined space is very deadly because it will quickly consume the available oxygen.

Other work activities that are hazardous in nature are those that can constantly increase the temperature inside the confined space. Aside from hot work, strenuous activities will lead to increased body temperatures which can lead to discomfort and breathing difficulties.

Hazards from Outside the Confined Space

The last factor to consider before starting the work in a confined space is hazards from outside the workplace. The confined space assessment form from the Health and Safety Executive (HSE) recommends isolating the confined space to prevent any external hazard.

One of the primary external hazards mentioned in the form is the ingress of substances. Ingress of substances refers to any risk that comes from materials that may enter the confined space and compromise the safety of the workers. Some of the most common substances that infiltrate a confined space are groundwater, rainwater, and exhaust gases from combustion engines.

What Precautions Should be in Place According to the Confined Space Assessment Form?

After careful consideration of the factors prior to starting the work, the next step when conducting a confined space assessment is to set up safety precautions.

In the confined space checklist hazard assessment from the HSE, there are twenty elements to consider:

  • Proper supervisory arrangements
  • Adequate competence of workers
  • Proper communication system
  • Proper testing and monitoring arrangements for air quality
  • Gas purging for spaces with flammable and toxic gases
  • Proper ventilation systems
  • Removal of residues in the confined space
  • Isolation from ingress of gases, liquids, and other flowing materials
  • Isolation from hazards of mechanical and electrical equipment
  • Using suitable equipment depending on working condition
  • Complete PPE and RPE
  • Careful usage of portable gas cylinders and internal combustion engines
  • Minimizing the usage of pipes and hoses
  • Ensure quick and easy points access and egress
  • Putting up fire prevention measures
  • Setting up suitable and adequate lighting
  • Removal of any sources of static electricity and ignition
  • Prohibition of smoking inside the working area
  • Sufficient arrangements for emergencies and rescue
  • Limit the work time inside the confined space

When setting up these elements of precautions, it is recommended to put everything in writing and keep every procedure well-documented. Doing so will ensure that the implementation stage of these precautionary measures will have a good sequence and be done properly.

Employee crawling in a confined space under the house to perform maintenance


How can a Digital Checklist be Used to Streamline a Confined Space Hazard Assessment?


Not only are confined spaces claustrophobic, they are typically poorly ventilated. For that reason, they can cause a life-threatening event if you don’t do your due diligence. Small spaces leave small reaction times in case of toxic substances, fire, or other hazards lurking unseen to the human eye. That’s why it’s all the more important to inspect spaces before sending your employees in. Luckily, Lumiform has plenty of templates and checklists to help you assess the safety of a less-than-roomy work environment.


Learn more about the other advantages Lumiform has to offer:


  • To help you get started, Lumiform has over 9,000 checklists and templates in its library for you to browse and adapt to your individual business needs
  • With the Lumiform app and software, you’ll be immediately notified if hazards are found on site
  • You can save time and money by completing inspections up to 30%-40% faster than with a regular pen and paper checklist.
  • Prevent injuries, deaths, and lawsuits by performing more thorough inspections than ever before.
Try Lumiform for free


Employee using a confined space assessment checklist to inspect job site

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