3 instructions to prevent HST after a fall arrest


Harness Suspension Trauma (HST) is a risk for everyone using a fall arrest system, which is often overlooked by users as well as the owners of the system. This post explains what HST is, and how three simple instructions can reduce the risk that users will suffer from HST after a fall arrest.

To illustrate this, we’ll cover all the appropriate actions that a user should perform in case of a fall, by means of the following scenario.

A scenario:

Imagine two glaziers whose job for today is to replace the windows of the third floor of an office building from the outside. They need to work while standing a small ledge without edge protection.

An overhead lifeline is installed to the overhanging roof structure in order to protect workers on the ledge, as shown in the picture on the right.

The glaziers are trained in the use of a fall arrest system, and are supplied with all the required Personal Protective Equipment (PPE): a safety harness, a fall arrest device with integrated energy absorption and some carabiners.

They perform a pre-use check on all PPE, in accordance with the instructions in the manuals of their equipment.

They put on their helmet and don their harness, ensuring a snug fit. They check each other’s harness and connect themselves to the overhead lifeline before stepping outside the safe zone.

If you think that the two glaziers are now ready to use the fall arrest system, you’re wrong!

Yes, they are using the system correctly. Yes, the system should arrest their fall before they hit the ground. But then what?

Sometimes, the emphasis that is put on preventing or arresting falls leads to the false impression that the danger is over when a fall is arrested. Nothing could be further from the truth.

What happens when a fall is arrested?

Say that at some point during the window replacement, one of the glazier trips or missteps and falls off the edge. The fall arrest system activates. The fall is arrested and the shock on the glazier’s body is limited thanks to his fall arrest device.

But then what? He’s now dangling in his harness several meters above the ground and is probably unable to stop himself from panicking. He was just exposed to a major shock and a collision may have knocked him unconscious.

Harness Suspension Trauma

Hanging in a harness is better than a falling three floors to the ground, but make no mistake: the glazier will be far from OK. His blood circulation will be disrupted because the leg straps of his harness are squeezing the veins in his groin. This impedes blood flowing back to his brains and the vital organs in his torso. This underestimated danger is known as Harness Suspension Trauma.

The symptoms of HST may become noticeable in a matter of minutes: the glazier may become lightheaded and/or nauseous, his limbs may start to feel tingly or numb, he may feel like he’s about to faint, he may experience visual disturbances. HST could lead to unconsciousness and even death if he’s not rescued in time, due to oxygen deprivation of the brain and other vital organs.

Harness relief straps

Harnesses can be equipped with a relief strap: an extra strap (or two), attached to the harness near the user’s hips. The user deploys this solution when suspended in his harness, and places his feet on the relief strap. This allows him to stretch his legs so that his blood circulation is not impeded.

When it comes to preventing HST, the importance of using a relief strap cannot be stressed enough. It is doubtlessly the simplest ways to prevent permanent, long-term injuries when working with a fall arrest system. The use of a relief strap drastically improves the condition of a user suspended in a harness, and thereby increases the chance that a user is rescued before losing consciousness.

How proper instructions can save lives

Let’s see what would happen when the glazier is properly prepared for a potential fall:

  • The PPE did exactly what it should do, as the glazier has ensured by inspecting it before use. His helmet prevented that he was knocked out by an impact. So here he is: shocked, but alive and conscious.
  • The glazier is aware of the danger: HST. He knows exactly what to do. He deploys the relief straps to relieve the pressure on his groin. This keeps his blood circulating so that HST doesn’t get a chance.
  • In accordance with the instructions he’s been given, he hasn’t left the sight of his co-worker who has witnessed the fall and who knows exactly who to call for help. The emergency response officer on duty is made aware of the situation promptly. If there is no trained emergency response officer onsite, then the fire department should be notified by calling the local emergency number.

In this scenario, it is very likely that the glazier will be rescued before sustaining serious injuries from Harness Suspension Trauma.

Rescue plan

If you’re responsible for the safety of people working with a fall arrest system, it’s your duty to ensure that workers use the system properly. Giving clear instructions on how to prevent Harness Suspension Trauma is also part of this duty.

You should have a rescue plan in place, which defines how workers hanging in a harness should be rescued. The contents of this rescue plan are not discussed in this post. However, the instructions provided here can be used in any situation where fall arrest is used to protect workers.

XSPlatforms has established three simple instructions that can be passed on to workers using a fall arrest system, that help to prevent that users fall victim to HST when their fall is arrested. To make this as easy as possible, we’ve designed a poster that explains these instructions in plain English.

The poster is free for you to use. Hang it in a place where it is visible for workers, for example near the roof entrance or at the location where the PPE is kept.

8 Comments. Leave new

  • Thanks a good article

  • Darrel Baillie
    21 October 2016 17:26

    Awesome article. Thank you for the information.

  • Valueable article, thanks or upload.

  • Steve jones
    6 December 2016 21:33

    Did anyone ever die from HST?

    • No. It’s a theoretical injury, that has little empirically defensible data. It is possible, but highly unlikely to have all this go on, absent any other injury or malady of the person. We know of many long suspensions with no problems. People get numb legs sitting too long on toilets, and we haven’t yet created a market for step stools, or suspension straps to keep the pressure off our legs while on an extended potty break. There is certainly comfort value, and the value of employee morale and confidence in using relief straps. We also have a self rescue ladder that deploys above the workers head ( anchor point, to allow them to climb back up to where they left from without disconnecting. All good things to consider. I personally do not emphasize the trauma issue, since your kind of question is a reality, that takes away from the other more likely benefits. As with any safety, scaring workers is not usually the best way to sell them on it.

  • Excellent article. Great infographic as well!

    As a roof anchor point installer in Sydney, this is an awesome resource that I intend to share with my clients. Much appreciation from a fellow height safety professional in Australia.

    We have created a Height Safety Statistics infographic if any of your readers would like to have a look – http://www.sydneyanchorpoints.com.au/FAQ/working-height-safety.htm)


  • Thanks for the excellent article! As an offshore physician, I’m constantly informing and training the workers, along with the HSE team, on how to prevent and deal with situations in which HST can be a major problem. It will be very useful for our future meetings!

  • Jeremy S Preston
    4 December 2019 06:23

    Thank you for the article very well could save someone’s life hope this finds you and yours in health and happiness


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