Discusses issues of suspension trauma, clarifying some possible misperceptions.
Put Suspension Trauma in Proper Perspective
Regarding the March 2003 Occupational Health & Safety article "Will your Safety Harness Kill You?," the American National Standards Institute (ANSI) Z359 Committee on Fall Protection and Related Systems would like to clarify the causes and risks associated with motionless harness suspension and trauma. While the committee agrees with many of the observations and recommendations made therein, there are several points that deserve clarification:
1. The article stated that suspension over 5 minutes in a safety harness can cause death, citing Paul Seddon’s report to the Health and Safety Executive (UK) entitled, Harness Suspension: Review and Evaluation of Existing Information. The UK report clearly documents the existence and importance of suspension trauma, but also shows that the related risks stem from motionless suspension (e.g., worker is unconscious or incapacitated) and not from suspension in the normal course of work. Because this important distinction is not made clear in the article, readers might mistakenly conclude that any suspension over 5 minutes can lead to death. Such a conclusion would conflict with the advice given in section 1.6.1 of the UK report that states "... anyone who is suspended in a harness may be at risk of suspension trauma if they were to hang motionless in the harness" and "... leaving an unconscious person suspended on a rope can cause death in less than 10 minutes."
2. The article also provided two hypothetical examples of how workers might die as a result of suspension trauma, but neither example provided a clear picture of how suspension trauma may have contributed to the worker’s death, nor is motionless suspension mentioned as a chief risk factor. When examples of deadly risk factors are given, a more detailed analysis should be used to reduce the opportunity for misinterpretation. This might have been done in the example of the carpenter’s death by mentioning that he sustained a head injury in the fall, causing loss of consciousness. Because he was working alone (i.e., had no rescue plan), and was suspended for more than 15 minutes while unconscious, he eventually died due to suspension trauma. The research shows that the level of risk to the worker suspended after a fall becomes more severe if the worker is unconscious or incapacitated by other trauma.
3. It is important to keep what is known about suspension trauma in perspective. The UK report states that over 5.8 million on-rope hours have been logged by qualified IRATA rope access technicians without any reported incidents of suspension trauma. Several deaths that occurred in caving and mountaineering are discussed in the report, but many of these had additional contributing factors such as prolonged suspension (several hours), harsh environment, and lack of harness. The death of a soldier in first aid training is discussed briefly, but he was "left unobserved for about six minutes," suspended only by a strap around the thorax (it is not stated how long the soldier hung before he was left unobserved). The UK report does not document any worker deaths caused by suspension in a harness, but it does show an urgent need for education and action regarding suspension trauma. For more information on suspension trauma, Paul Seddon’s report to the HSE may be downloaded at http://www.hse.gov.uk/research/crr_htm/2002/crr02451.htm
Issues related to suspension trauma are currently under consideration by the Z359 committee. The committee is currently revising the Z359.1 standard, and may be approved by fall 2004. The revised standard will address training, use, and equipment specifications for personal fall arrest, work positioning, travel restraint, and rescue systems. For more information, please contact the Z359 secretariat, the American Society of Safety Engineers (ASSE), at 847-699-2929, attention Patrick Arkins.Jack Dobson, CSP
Chair, Z359 ASC