Redefining the Safety Hierarchy in a Confined Space
What are the steps you should first consider to ensure your confined space entries are safe and that workers are best equipped to respond if they are met with a life-threatening hazard?
Friday, August 25, 2023
Section: OSHA

construction worker

A lot can happen in four minutes, especially when those four minutes are spent in a confined space. Confined spaces are prone to oxygen displacement, and after just four minutes without oxygen, you can experience brain damage or even die. It should be no surprise, then, that confined spaces are the leading cause of multiple fatalities in the workplace. That’s why it’s so important to take extra precautions to ensure safety in confined spaces.

It’s an age-old horror story: a worker enters a confined space, most likely for routine maintenance or repair, and an atmospheric hazard is present. When the entrant doesn’t respond to the hole watch, their supervisor and peers get worried, so one of them enters the confined space to check on the original entrant only to be overcome by the same gas hazard. Unfortunately, this scenario is too common—The National Institute for Occupational Safety and Health (NIOSH) reports that 60 percent of confined space deaths are among these “would-be” rescuers who enter a confined space without understanding the hazards within.

When workers in confined spaces need your help, you can’t act on impulse – you need to be prepared with a plan and proper equipment in place long before the first worker enters a confined space. When creating a confined space entry plan, however, you need to think bigger than what the “traditional” hazards are to isolate.

While most would say eliminating the hazard completely should be the first step in your safety hierarchy, it’s impossible to completely eradicate every potential hazard workers face. Below are the steps you should first consider putting in place to ensure your confined space entries are safe and that workers are best equipped to respond if they are met with a life-threatening hazard.

Potential Risks in a Confined Space

Because you can’t eliminate every potential hazard, you should first consider your overall approach to confined space entries. Before workers enter a confined space, you must complete a risk assessment (examining the environment in/around the confined space for entry location and size, energy or chemical sources, and lockout points), hazard assessment (examining what hazards workers could be exposed to), identify the personal protective equipment workers will need, and select properly trained workers to perform the job.

After you’ve checked and prepared your equipment, you should sample the atmosphere from a safe location. Once you’ve safely approached the confined space and you’ve begun taking samples, you need to take things like stratification of gases into consideration.


Gases settle in a space based on their weight in relation to air. Toxic gases that you would commonly encounter in confined spaces have a typical stratification pattern. For example, hydrogen sulfide (H2S) settles at the bottom—it’s a heavier-than-air gas. Carbone monoxide (CO), which is slightly lighter than air, tends to settle in the middle, while methane sits on top. However, these are not absolute rules.

You also need to take into consideration things like air current or ventilation. You may find H2S at a different level due to these factors and when you see those readings on your gas detector, that doesn’t mean that your instrument is incorrect. It is likely detecting that gas at a different level. Remember, these are general guidelines, and for more specific information concerning confined space entry, consult your regulatory agencies for details.

That said, no two confined spaces are the same. But they all have the potential to harm workers if you don’t identify, monitor, and control the dangers within, which means you need to ensure that your people – both full-time employees and contractors – have the right equipment to get the job done.

Communication Amidst the Inability to Communicate

Once you’re aware of the risks within each confined space, supervisors need to ensure that workers (including contractors) understand the hazards of the space and that they have the safety and communication tools they need.

A safe confined space monitoring strategy requires a great deal of teamwork. After pre-entry testing, it’s not enough to check for gas hazards and then throw your monitor back in the truck — confined spaces must also be monitored by an attendant. And in some instances, one attendant can serve multiple confined spaces if he or she can monitor the atmosphere and communicate with the entrants in each of those spaces.

As you can imagine, this can sometimes make it difficult for the worker inside to communicate with the attendant. The concern here is that the atmosphere inside the confined space can change quickly and unexpectedly. But if the worker inside the space doesn’t have a monitor, and the attendant is addressing an issue within another confined space, that worker could be in grave danger.

The safest practice, therefore, is for a worker within the confined space to have a personal monitor that can share gas readings to the attendant’s monitor – allowing for communication where it is normally extremely limited. If a worker inside the confined space encounters a gas hazard, is immobilized, or needs emergency assistance for any other reason, the cause of the alarm is instantly relayed to the attendant’s gas detector.


Continuously Monitoring a Space

Even with an attendant watching for hazards, continuously monitoring the confined space is one of the best things you can do to prevent fatal accidents.

Since many gas hazards are heavier than air, they fill a space from the bottom first. If your entrant is standing in a confined space and it starts to fill with a gas, continuous monitoring with a pumped gas detector can alert both of you to the hazard before it ever reaches the person inside. This allows them to exit the confined space safely.

But how will others know if a confined space entrant is at risk? Area gas monitors can help because they provide clear audio and visual alarms so everybody in the area knows there is a gas hazard. You can take this a step further with live monitoring. Live monitoring allows anyone, anywhere, to be alerted when gas hazards put workers in danger so that everyone can respond accordingly.

An additional step to continuously monitoring a space means sampling and monitoring every confined space a worker may enter – both permit-required and non-permit-required spaces. Even in non-permit-required spaces, you’ll still want to monitor the space for gases and other hazards. Why? Well, there are multiple variables to consider.

For example, what if the outer part of the confined space has cracked, causing it to rust? Due to the rust that has been slowly forming in this space, there is a lot of displaced oxygen. So, when the confined space is opened for the first time in a year, there is suddenly nothing to breathe and because the space isn’t being monitored, no one would be aware that anyone experienced a fatal event.

By continuously monitoring spaces, both before and during an entry, you can ensure that real-time gas readings, man-down alarms, and panic alerts are shared with both peers nearby and safety personnel far away to help mitigate hazards before an evacuation (or worse) is needed.

Training Workers on Your Confined Space Entry Plan

Even with the right personal protection equipment, gas monitoring program, and a solid monitoring and communication strategy in place, you can’t stop there — you need a plan.

With a plan in place, you must now train your workers on it. After all, 85 percent of fatalities in confined spaces were among people who hadn’t been trained; therefore, it’s crucial that your team is trained and understands how to safely test the atmosphere within a confined space.

Having a set plan in place, knowing how to use your gas detection equipment, incorporating live monitoring options and data, and consistently practicing emergency response drills is critical in not only establishing control during an emergency but keeping your team safe during a time when every moment matters and ensuring everyone goes home safely.