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How to Select the Right Respirator for Confined Space Work

By Daniel Clark | Reviewed by Malcolm JacobsCheckmark
Published: June 15, 2022
Key Takeaways

When dealing with atmospheric hazards, using the correct respirator is essential for keeping workers safe.

Caption: Storage tank entry door Source: noomcpk2528 / iStock

In 2021, three workers in the Bahamas entered a metal storage tank to perform a routine cleaning task. The first to enter the space was quickly overcome by the hazardous atmosphere and lost consciousness. The second entered to rescue his fallen co-worker and lost consciousness as well. Then the third worker followed, with the same result.

Sadly, all three perished in the tank that day. Tragically, versions of this scenario are so common that there is a similar cautionary tale almost anywhere you go.

Confined spaces are hazardous and many of them can be deadly, yet they are often unassuming. In fact, that's one of their greatests dangers - the risks often go unnoticed and not everyone who enters a confined space is aware of the hazards they will be exposed to. It takes training to make sure all workers are aware of the risks involved, the safety measures they need to follow, and how to correctly select and use the right respirator.


Atmospheric Hazards in Confined Spaces

Confined spaces range from the unassuming pit or trench all the way up to a critical vessel entry operation. Yet all of them contain hazards, both seen and unseen.

Perhaps the most significant of these hazards are those that fall under the category of atmospheric hazards. This includes exposure to harmful substances as well as oxygen imbalances. These are particularly dangerous because they can crop up with little or no conspicuous warning and can quickly leave a worker dead or unconscious.

The example that opens this article was a case of oxygen deficiency created by the natural process of scrap metal rusting. There would have been no way to detect this without the appropriate instruments and training. A suitable protocol would have prompted the workers to test the atmosphere before entering and to mask up with a respirator that can keep them safe from the hazards detected in the space.

(Learn more in 7 Things to Consider Before Entering a Confined Space)

Preparing for Confined Space Entry

Careful preparation can keep workers safe in confined spaces, and there is much to do before the work even starts.

Depending on the potential hazards present, all workers have to be:

  • Trained in performing confined space entries
  • Fit tested for the respirators they will be using
  • Trained on any equipment they will need
  • Well-versed in the confined space rescue plan
  • Trained on the relevant lockout/tagout procedures

And the list goes on. All of this is part of a robust confined space entry program, which is in turn a part of a complete safety management system.

A formal hazard assessment will reveal the hazards likely to be present in a given confined space and for specific tasks performed in it. This must be completed prior to any work and carefully reviewed by competent individuals.

The assessment must consider both the nature of the task and the nature of the environment in which it will be performed. For example, a confined space that has limited ventilation may not be inherently problematic, but welding and other “hot work” performed inside it can produce fumes, introduce ignition sources, and consume oxygen all at the same time. We have to take these factors into account and consider how they create or increase the risks. Based on that analysis, we can then choose the appropriate control measures for the situation, including which respiratory protection will be needed.


If atmospheric hazards might be present in the confined space, the atmosphere must be tested before any entry can take place. Jurisdictions have different rules about how and when this must be done, but all of them involve collecting a grab sample of the internal atmosphere with a method that doesn't require entry, such as a wand or pump. That sample is used to detect any hazardous substances in the atmosphere and assess the concentration of oxygen. The nature of hazards, the contaminants, and the oxygen density in the space will help you determine which type of respirator will be appropriate.

Finally, review the ANSI/ASSP Z117.1 standard to ensure that your work plans meet their requirements for entering, exiting, and working in confined spaces at normal atmospheric pressure. You should also consult it to help you evaluate confined spaces, whether they are permit-required spaces, and what worker training is needed to enter and work in them safely.

(Find out What Your Confined Space Entry Program Needs to Cover)

Types of Respirators for Confined Space Entry

Air Purifying respirators

The basic respirator for confined space operations is the air purifying respirator, which is essentially a filter you breathe through.

There are simple non-powered versions of these as well as powered air purifying respirators (PAPRs) equiped with a motorized fan to move air through the filter. This significantly improves the comfort level of the user, allowing them to breathe more or less normally while still getting full protection.

Whether they're powered or not, these respirators are fitted with cartridges that filter specific contaminants. These are rated for different usages, so it’s important to select the one appropriate to the activity in question. An oil-proof full particle filter (P100) on a half mask offers great protection, but it’s not going to do you much good if you’re working with ammonia - not to mention you’ll be working blind!

Supplied Air Respirators

When the atmospheric risks are more elevated, confined space entry will require the use of a supplied air respirator and full mask.

This type of respirator comes in two basic varieties: the Self-Contained Breathing Apparatus (SCBA) and the Supplied-Air Breathing Apparatus (SABA). The type of work and the environment in the space are the two major factors in determining which of the two is the ideal choice.

Supplied-Air Breathing Apparatus

A SABA is typically used for longer entries in relatively predictable environments. This respirator supplies clean breathing air through a full-face mask connected by a hose to a manifold and compressor outside the confined space.

The main advantage of this type of respirator is that workers can generally be "under air" for a long period of time. However, there are also a number of drawbacks. For instance, the hose tethering the user to their air supply can become tangled or create a tripping hazard. It can also become disconnected, making it the wrong choice for any environment that is considered immediately dangerous to life and health (IDLH).

Self-Contained Breathing Apparatus

The SCBA is the terrestrial counterpart to the SCUBA systems used by divers. It supplies clean breathing air to the user through a full-face mask. Unlike the SABA, however, an SCBA's air supply is portable and carried on the worker's back. They are commonly used by firefighters, oil and gas workers, and for entry into any space that has an IDLH atmosphere.

The big downside with the SCBA is the limited supply of air. Even a full tank will only last 30 minutes - and someone really exerting themselves can polish one off in half that time.

(Learn more in SCBA 101 - Meet the Respirator That Will Save Your Life)

Respirator Fit Testing

No matter what type of mask is needed, it needs to fit the wearer in order to work. If the rubber can't form a seal that maintains pressure inside the mask, it simply won't be able to do its job.

To ensure that this is the case, each worker must be given a fit test before using their masks. These tests ensure that the mask is properly sized and creates the seal needed for it to function.

It's important to note that even a perfectly sized mask can't form a seal against facial hair. Workers who might have to don a mask for confined space entry, then, must be clean shaven to ensure their safety.

(Find out How to Complete a Respirator Fit Test)

Mask Up, Stay Safe

A lot of things can go wrong when entering a confined space, and those things can happen quickly. That's why using the correct respirator is essential. When there are atmospheric hazards present, a respirator is one of the few things that will keep the entrant safe from harm.

Always take the time to assess the atmospheric hazards, equip workers with respirators adequate to those hazards, and ensure that they are properly fitted. Anything less is a risk not worth taking.


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Written by Daniel Clark | Safety and Quality Management System Specialist

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Daniel Clark is the founder and President of Clark Health and Safety Ltd., providing safety and quality consultation across various industries in Calgary, Alberta. Daniel has a Bachelor of Science degree, certification in health and safety, certificates in both CAD design and CNC, auditing certifications and the designation of Canadian Registered Safety Professional. Being raised and practicing in Calgary, the heart of Canada’s energy industry, most of Daniel’s career has been energy related. He has performed safety and quality roles from field supervision to office-based administration and management. Daniel’s consulting business has worked with organizations offering engineering services, restoration, pipeline, environmental, manufacturing and food service.

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