Imagine a place with only one exit, and poor ventilation. Image working in such a place and having a fire, or dangerous fumes, or heat stroke, or a heart attack. How will you escape? Will you be able to reach the single exit before you are suffocated, burned to death, or dying because no one can get to you in time? This scenario is all too common when working in a confined space.

Now many of you who have read my work – here or elsewhere – are probably well aware that the editorial staff of Health & Safety International give me a lot of latitude to wander off point, inject a bit of humour, or even skip the topic altogether. I think I meet the intent, which is to say, to provide useful information in a way to engage the reader; there won’t be much of that here (well, I mean I will do my best to stay on point, I still want to engage the reader… are you still there?)

All the topics printed in this magazine are important, and while I have no personal experience with confined spaces (I have never died in one, had a near miss, or even had a colleague, friend or family member die from a confined space incident) and yet somehow this hazard is especially close to my heart.

I’ll begin with the basics a confined space is any location that meets the following criteria:

• Has points ingress and egress which restricts or impedes emergency response or evacuation

• Is poorly ventilated, and

• Is not intended for continuous worker occupancy

Personally, I think the first two criteria are most important, I mean seriously, does anyone think that a work area that meets these conditions are acceptable irrespective of whether or not workers continuously occupy it? So we’ll focus on the first two hazards in the greatest detail.

“work in confined space can create a risk of death from hazardous substances or dangerous conditions such as lack of oxygen or a build up of water”

According to Public Health Scotland, “Work in confined spaces can create a risk of death or serious injury. This could be from exposure to hazardous substances or dangerous conditions such as lack of oxygen or a build up of water.

Examples include:

• Pits and trenches

• Sewers and drains

• Vats, silos and tanks

• Chambers and ducting

• Unventilated or poorly ventilated rooms

People are killed and seriously injured working in confined spaces. This includes people trying to conduct rescues without the proper training or equipment. Where possible, avoid the need to work in confined spaces by using remote access methods.

Hazards when working in confined spaces include:

• Lack of oxygen

• Lack of natural light

• Dusts in high concentrations such as flour

• Liquids and solids suddenly filling the space

• Hot working conditions increasing body heat

There is a risk with gas, fumes or vapours filling the space as these can be flammable or poisonous.”1

One example of a potential confined space is ovens. I once worked as a Culture Transformation consultant to a large automobile manufacturer (this was before I worked in safety) and was tasked with developing technical training for newly installed heavy equipment. One of the pieces of equipment was an oven. It met all the criteria of a confined space. The oven was used for hardening epoxy. Epoxy can create a hot gooey mess that, if allowed to harden, can transform into a solid blob harder than concrete, so if the plant had a spill workers had to quickly enter the oven and remove the epoxy before it hardened. Unfortunately, there was no way to open the oven from the inside since under pristine operating conditions there is no reason a person should be in the oven. Now clearly this hazard goes beyond merely a typical confined space, but once we spotted the design flaw the plant was quick to install emergency latches on the inside of the oven. No one was harmed and there were no near misses, but I think the story nicely illustrates the need to look beyond the obvious and to be extremely vigilant in our risk assessments – confined spaces can crop up in the strangest places.

Situational awareness is vital to avoiding the too often fatal consequences of a confined space incident. I remember years ago I was walking to my local chemist to pick up some medicine when I happened upon a worker in a pit (he was doing maintenance on the city’s water lines.) I looked down into the pit which was over three meters deep. Water swirled and roiled around the man’s feet. There was no ladder and if the waters continued to rise he could have easily drowned. I shouted down to him and told him that he needed a spotter because he was in a confined space and he could easily be killed without anyone knowing it. He told me that he hadn’t thought of that, but there were only two people on site: his boss and him and he doubted that his boss would agree to be a spotter. I thanked him and asked where I could find his boss. He told me his boss was working about a block in the direction I was headed so I continued along. When I reached the area where the worker told me his boss would be, I could not find a single soul. 

Then I looked down into a second pit only to find his boss in a similar situation. Again I talked to the worker. I asked him how he intended to get out and he told me that he would use the access portal walls for leverage and shimmy up the piping. I asked him if he thought climbing by using the wet wall as a foothold while wearing wet boots was safe, and he curtly told me all about how long he had been doing this work. I called the city water department, and explained that as a resident I was concerned by the lack of oversight. I didn’t get what I thought was a response that demonstrated appropriate concern and urgency so I called the governmental regulatory agency and reported the situation. The person to whom I spoke was very concerned and asked me for specific details (location, exact time I spoke with the people, etc.) They said they had a person in the area and would take care of it immediately. Then I called the company, which turned out to be a Canadian firm and asked to talk to the head of safety. I told the head of safety of the situation, and that if one of these men died I would personally take an interest in seeing them prosecuted.

On my return from the chemist’s – it took an inordinate amount of time because the chemist was a dimwit and despite the fact that my medicine should have been ready it wasn’t – about 20 minutes later, the entire worksite had been shut down. The head of the city’s water department and a person I later learned was the company’s project manager were voicing their displeasure to both men.  To some extent it restored my faith in regulatory agencies and enforcement.  Were these men really to blame for risking their lives? Did they fully understand the risk they were taking? Probably not, and that is precisely why it is so important that we train workers how to identify, and safely work, in confined spaces.

“the first instinct of many people in the case of a potentially fatal incident to rush headlong into the kill zone, leaving two people (or more) dead”

Knowing the dangers is not enough.  When working in confined spaces workers must have a plan and a good portion of that plan should be devoted to emergency response. Let’s take a look at what a good confined space should contain:

1. Entry requirements.

2. Monitoring requirements.

3. Personal Protective Equipment (PPE) requirements

4. Emergency response and rescue requirements

Entry requirements

In many jurisdictions, workers are required to have a confined space work permit before they are even allowed to enter a confined space. Permits are typically required when, in addition to the criteria already stated one or more of the following are present: now, a permit-required confined space will contain all of the above, plus one or more of the following2:

A substance that has the ability to engulf or asphyxiate the entrant. These substances can include (but are certainly not limited to) explosives, highly flammable liquids or gases, or gases that are heavier than oxygen and can force oxygen to the top of the space and leaving only oxygen-depleted ambient atmosphere in the work zone3.  Additionally, sometimes the very nature of the work can deplete oxygen and create a lethal atmosphere. Even something as simple as breathing – for a prolonged time in a poorly ventilated area – can create an oxygen depleted, and extremely hazardous, atmosphere.

A potentially hazardous atmosphere. Not to cast aspersions on the source of this criterion, but this is dangerously vague Just what constitutes a “potentially hazardous atmosphere? In this case, I like the lack of specificity; it reminds us of the importance of considering the vagaries endemic to a dynamic hazard that can go from benign to fatal in an instance. When developing a plan, one should always consider that the atmosphere of a confined space can, and often do, change rapidly and one must identify the appropriate mitigation measure that should be taken when change occurs.

Spaces with inwardly converging walls within the space or a floor that slopes downward, tapering to a small cross-section. This condition is all about mobility. As I have already mentioned, conditions in a confined space can rapidly change and sometimes that rapid change means that the space must be immediately evacuated. Inwardly converging walls, downward sloping floors or a narrowing of the space all make rapid egress significantly more difficult.

Contains any other serious safety or health hazard. Not all hazards are atmospheric. The confined space may contain exposure risks, risk of drowning (as in my example), electrocution, asbestos or other exposure risk, biohazardous waste, or any number of other hazards that increase the risk of entering the confined space.

So what is a permit to work? According to Enablon, “A safe work permit (also known as a “permit to work”) is a document that includes a description of the work to be performed, the hazards involved, the precautions to take, the required authorisations, and other elements. It is a written record authorising a specific work at a specific location, and for a specific time.”4

In some cases it may be necessary to isolate hazardous energy (aka lockout/tag out) before entering a confined space, if this is the case this requirement should be identified in the permit to work.

Monitoring requirements

The monitoring requirements for working in a confined space vary depending on the hazards associated with the confined space, but probably the most common is gas detection.  There are great articles written by far smarter people5 than I on how to select the appropriate gas detection devices so I won’t belabor the point.  I will however reinforce the very important point that it is absolutely essential to have a person OUTSIDE the confined space monitoring all hazards foreseen and unforeseen, and who is continuously ensuring that the worker is in good health and  does not require rescue.

The air quality must be measured before the work begins you may have to use temporary ventilation or pump in nonhazardous atmosphere before beginning work.

PPE requirements

Much like monitoring requirements your PPE requirements are going to depend on the circumstances in which a worker is working while in a confined space. It is not uncommon for work in these area to require respirators or Self-Contained Breathing Apparatuses (SCBA) which may require advance time to procure so it is essential that you identify the PPE that will be required early in the planning process.

It’s also important to ensure that the PPE doesn’t introduce additional risk to the worker’s safety (limiting mobility or visibility for example). This is not to say that PPE that does increase the risk means that you are not required to use some for of PPE, it merely means that you need to explore other ways to protect the worker that introduces less risk than your first choice for PPE.

Emergency response requirements

When things turn ugly in a confined space seconds count. Far too often crucial time is lost looking for emergency equipment because it was not obtained and placed within easy access by the person monitoring the confined space. Also, you should consider appropriate PPE for first responders. The first instinct of many people in the case of a potentially fatal incident to rush headlong into the kill zone, leaving two people (or more) dead. When conducting a risk assessment don’t forget the dangers associated with a rescue should one be necessary.

Public Health Scotland (an excellent resource) offers these additional recommendations regarding emergency response:

“Put emergency arrangements in place before any work starts. You must put suitable and sufficient measures in place to make sure employees can be rescued safely if required. You should also consider

• First aid procedures

• The safety of rescuers

• Liaison with emergency services

They must be appropriate to the hazard presented by the activity.

• There must be an effective means of communication for raising the alarm both from the confined space and by someone outside

• Work in confined spaces is often carried out at night, weekends and times when the premises are closed, for example holidays. Consider how the alarm can be raised

• Provide rescue and resuscitation equipment. This will depend on the likely emergencies identified

• It may be necessary to shut down any adjacent plant before attempting emergency rescue. Ensure access and a means to safely shut down is available

• Consider how the local emergency services would be made aware of an incident. Plan what their route of access is. Also consider what information about the dangers need to be given to them on their arrival


Those who are identified as rescuers need to be:

• Ready at hand

• Properly trained

• Fit to carry out their task

• Protected against the cause of the emergency

• Capable of using any equipment provided for rescue, for example breathing apparatus, lifelines and fire-fighting equipment”6

Other considerations

It should go without saying that only those individuals who are properly trained, and physically able to perform the work (for example they don’t suffer from a chronic respiratory or heart condition that would put them at greater risk) should enter a confined space, but in safety nothing goes without saying.

Final thoughts

Working in a confined space is intrinsically risky and as much as we would love to remove the hazard completely there is little chance of us doing so. Preparation is the single most important factor in whether an incident is a near miss or a fatality, so hope for the best and prepare for the worst.

Read. Learn. Live. Share. Inspire. 

3 It’s worth noting that many fire suppression systems use this phenomena to extinguish fires in areas where water would pose a threat to people or equipment.
5 Okay maybe not FAR smarter, but at very least more conversant in the nuanced world of gas detection.