How to Avoid Asphyxiation in Confined Spaces

Construction workers face some of the most dangerous health hazards, particularly when working in confined spaces where asphyxiation is a significant risk. The dangers are accentuated by the conditions within these spaces, which often have limited oxygen supply. In this blog, we’ll go over different methods to avoid asphyxiation hazards in construction-confined spaces. 

Confined Spaces: The Stats

A breathable atmosphere is one where oxygen is kept between 19.5% to 23.5%. When that amount drops by even 1%, breathing can become a challenge. Overweight or muscular individuals may have more difficulty breathing under such conditions and can get disoriented faster.

When the oxygen level drops between 12% and 16%, symptoms such as dizziness, unconsciousness, and headaches appear. Moreover, death occurs within 6 minutes if the level drops to 6 or 10%, depending on the health, work environment, and physical activity level of the confined space worker.

From 2011 to 2018, 1,030 workers in the U.S. died from occupational injuries involving a confined space, highlighting the critical need for stringent safety measures.

What Are Confined Spaces?

The Occupational Safety and Health Administration (OSHA) defines a confined space as:

• Sufficiently large for a worker to enter fully and perform tasks.
• Not designed for continuous occupancy.
• Restricted in terms of entry and exit.

Examples of common confined spaces in construction include tanks, vaults, silos, and manholes. These are spaces where oxygen levels can be compromised, either naturally or through work processes, and often, there is a construction confined space permit system in place, meaning they require a permit due to the risks of engulfment or asphyxiation.

How Oxygen Depletion and Toxic Gasses Can Occur in Confined Spaces

Oxygen depletion in confined spaces can occur from several sources, such as rusting iron, bacterial action, or displacement by other gases.

Limited air circulation within a confined space can result in an atmosphere that significantly differs from the external environment. Deadly gases may accumulate, and organic materials might decompose within these areas.

Additionally, the presence of other gases or chemical reactions, such as rusting, can reduce oxygen levels, further compromising the safety of the space. Toxic gases like carbon monoxide or hydrogen sulfide might also accumulate, especially in areas where equipment is running or where organic matter is decomposing.

How to Prevent Asphyxiation in Confined Spaces

Asphyxiation is the most common hazard in spaces that have limited space. The good news is that the risks can be reduced with a few precautions. Here are confined space safety procedures for workers to help you prevent asphyxiation:

1. Wear Personal Protective Equipment (PPE)

Before entering confined spaces, workers must be equipped with the appropriate PPE. This includes:

• Respirators: Necessary when adequate ventilation can’t be guaranteed.
• Safety harnesses: Essential for safe entry and exit, particularly in vertically oriented confined spaces.
• Gas detectors: To continuously monitor air quality for oxygen levels and toxic gasses.

These precautions help maintain a safe work environment and are integral to the confined space safety procedures for workers.

2. Purge the Confined Space Before Entry

Ensure all hazardous materials, sludge, and vapors are removed from the space before entry. Deposits can give off toxic vapors, dust, or fumes that can not only interrupt operations but can also cause serious illnesses.

Use mechanical ventilation to maintain breathable air without increasing fire risks. If steam cleaning is used for the purge, supervisors should allow the space to cool down first to ensure it is safe to work in.

3. Ensure Adequate Ventilation

Because confined spaces lack proper ventilation, it’s crucial to implement strategies to prevent suffocation. This might involve increasing the number of openings to improve air circulation.

However, mechanical methods to enhance the fresh air supply are often necessary. It's important to note that this does not mean introducing pure oxygen, as it could heighten the risk of fires or explosions, even from minor sparks.

Instead, normal ambient air should be directed into the space, particularly if there is the presence of compressed gases or if burning equipment is in use. Additionally, engine exhaust in an environment with a high oxygen concentration can lead to explosive conditions.

4. Check Entrance and Exit Size

Verify that the entryway of the confined space is sufficiently spacious for workers to access and operate within it. Workers should be able to enter freely with all necessary protective gear and equipment without obstruction, ensuring the area is secure for restricted use.

This protective gear is essential not only for routine tasks but also for managing potential emergencies. However, bulkier equipment can complicate entry, work, and exit from the space. If the entry is too narrow to accommodate bulkier equipment, consider equipping workers with air-line respirators instead of bulkier self-contained units.

5. Continuously Monitor the Air

Before workers are allowed to work in a confined space, the air quality of the confined space should be tested. This will show whether the air is free of toxic and flammable gases and if it has enough oxygen content that is fit to breathe.

Confined space atmosphere testing in construction should be carried out by a competent individual with equipment that can be calibrated. If the risk assessment reveals that the conditions of the space may change with time or during the work, the air quality should be tested continuously.

Confined Space Safety for Construction Workers With 360training

Understanding and adhering to confined space safety protocols is not just regulatory; it’s a crucial measure to protect the lives of construction workers. Always remember that safety in confined spaces starts with awareness and ends with strict adherence to proven safety standards.

Comprehensive training is essential for anyone working in these high-risk environments. OSHA mandates specific training for workers who will enter confined spaces. Our Confined Space Entry Training For Construction and Confined Space Entry Training For General Industry offers the most comprehensive overview of OSHA safety standards for working in or around confined spaces and teaches you how to protect yourself from confined space hazards. Check out our full catalog of courses on our website today!