Latest / Safe As Podcast / E51: The links between hazardous energy magnitude and injury severity

Transcript

E51: The links between hazardous energy magnitude and injury severity · Safe As Podcast

• 0:07
  Common safety approaches focus on evaluating hazards and risks,
• 0:11
  but what is the value of evaluating the sources and
• 0:13
  degrees of energy? What are the links between the
• 0:16
  energy exposure from a hazard and the severity of injury?
• 0:21
  Good day everyone. I'm Ben Hutchinson and This is
• 0:23
  Safe as a podcast dedicated to the thrifty analysis of safety,
• 0:28
  risk and performance research. Visit safetyinsights.org for
• 0:32
  more research. Today's study is from Hallowell
• 0:36
  ET al, 2017 titled Energy Based Safety Risk Assessment.
• 0:42
  Does magnitude and intensity of energy predict injury severity
• 0:47
  In construction, management and economics?
• 0:50
  The research is aimed to test if the quantity and intensity of
• 0:53
  energy observed before an incident predicts injury
• 0:57
  severity. That is, what are the links
• 1:00
  between a SIF or a serious incident or fatality and the
• 1:04
  energy exposure within the hazard?
• 1:07
  This one's a bit technical, so let's start with some
• 1:09
  definitions. Let's start with energy or
• 1:12
  hazard energy. You'll have to think back to
• 1:14
  your high school physics, but energy is the fundamental
• 1:17
  capacity of a physical system to perform work or induce change.
• 1:22
  In this context, we'll talk about hazardous energy.
• 1:26
  This refers to the form of energy exchange in excess of the
• 1:29
  body's threshold. So for instance, it's the degree
• 1:33
  of energy exchange that exceeds some sort of tissue of the body,
• 1:37
  therefore leads to injury. Even things like the hierarchy
• 1:40
  of control, which may not directly talk about energy,
• 1:43
  energy is still absolutely critical.
• 1:46
  There's energy magnitude, so that's the quantity of energy
• 1:49
  present in the hazard. It's measured using basic
• 1:52
  physics principles, so some examples are gravitational
• 1:55
  energy, motion energy, electrical energy, things like
• 1:58
  that. And for the patterns out there,
• 2:01
  we're talking about gravitational potential energy.
• 2:04
  There's also energy intensity. This is defined as the magnitude
• 2:07
  of energy divided by the area of contact between an object and
• 2:11
  the human body. Energy intensity is crucial
• 2:15
  because it accounts for the sharpness of an object.
• 2:18
  For instance, 1/2 kilo concrete chisel dropped from three metres
• 2:23
  despite having the same energy magnitude as 1/2 kilogramme tape
• 2:27
  measure dropped from the same height has significantly higher
• 2:30
  energy intensity due to its smaller contact area, leading to
• 2:34
  more severe injuries. Oh hey future been here despite
• 2:38
  knowing better. I keep saying heeka instead of
• 2:41
  hecka so if that triggers you then come at me bro.
• 2:46
  What were the methods? They collected a 505 injury
• 2:51
  reports from national databases and private companies focusing
• 2:55
  on incidents involving gravity and motion energy sources, and
• 3:00
  they processed the information describing the work environment
• 3:03
  and using this information, then calculated the magnitude and the
• 3:07
  intensity of energy. So what did they find?
• 3:11
  Perhaps not unexpectedly, they found strong statistical
• 3:14
  evidence that energy is a critical predictor of severity,
• 3:19
  So energy magnitude predicts the severity.
• 3:22
  Statistical analysis revealed a significant difference in energy
• 3:25
  magnitude across all injury severity levels.
• 3:28
  However, while energy magnitude is an effective predictor,
• 3:33
  energy intensity showed even stronger predictive validity.
• 3:37
  So, when accounting for the contact area between object and
• 3:40
  the human body, energy intensity displayed significantly less
• 3:43
  variability and overlap among different severity groups
• 3:47
  compared to energy magnitude. This suggests energy intensity
• 3:50
  provides a more refined prediction of injury severity.
• 3:54
  The study acknowledged that even with energy intensity, some
• 3:57
  overlap and variability existed between the injury severity
• 4:01
  distributions, which they found that the sort of residual
• 4:04
  variability is largely attributed to the vulnerability
• 4:07
  of specific body parts affected. For instance, a tape measure
• 4:12
  striking a worker's head was fatal, whereas a similar impact
• 4:16
  to a shoulder might not be. Similarly, a worker falling
• 4:20
  maybe .7 metres onto their back sustained minor injuries, while
• 4:24
  another struck by a wood panel with similar energy magnitude
• 4:28
  was killed due to being hit by a sharp object on a vulnerable
• 4:31
  body. Part. 1 of their goals of this
• 4:33
  study was to define high energy hazards.
• 4:37
  So what's the threshold between something that's fatal versus
• 4:40
  maybe a non fatal energy impact? Considering the minimum energy
• 4:44
  for a fatality was considered, but it proved really problematic
• 4:48
  for the least magnitude. For example, 590 joules of
• 4:52
  energy from a sharp object striking the skull was fatal,
• 4:56
  but the same energy from a flat fall might only cause minor
• 4:59
  injury. However, for practical use, the
• 5:03
  research suggests a more accurate high energy criterion
• 5:06
  for energy magnitude is approximately 2000 joules, which
• 5:11
  sort of equates to a work of falling 2.4 metres per energy
• 5:14
  intensity. A threshold of 2.56 joules per
• 5:18
  square centimetres was considered a reasonable
• 5:21
  threshold, even though it did include some non fatal injuries
• 5:24
  that were deemed to have a high potential for fatality.
• 5:27
  So this suggests at least based on magnitude, that hazard
• 5:31
  exposures that involve around 2000 joules or more are more
• 5:35
  likely to be fatal then exposures that involve less than
• 5:38
  2000 joules, accounting for the particularities like, you know,
• 5:42
  the sharpness and the body part vulnerability.
• 5:46
  So what do we make of the findings?
• 5:48
  The obvious one is there's potential as an energy based
• 5:50
  safety risk assessment that offers a scientific and rather
• 5:54
  objective method for assessing the safety risk.
• 5:57
  It can help practitioners forecast the severity of
• 6:00
  potential injuries by observing basic characteristics of the
• 6:03
  work environment based on physical laws.
• 6:06
  It could even fade into visual tools and heatmaps and building
• 6:10
  information modelling in AI. I think more interesting is
• 6:14
  research that resulted from this study in other research by the
• 6:17
  same research groups, particularly what they called
• 6:20
  Hagar or high energy control assessments.
• 6:23
  Just a really quick overview, but it's a method designed to
• 6:26
  measure safety performance by evaluating how adequately
• 6:30
  frontline employees are protected against life
• 6:32
  threatening hazards. It's computed as the percentage
• 6:35
  of high energy hazards that have a corresponding direct control.
• 6:39
  Now it's set up specifically to be focused on preventing sifts,
• 6:43
  the serious injuries or serious incidents or fatalities by
• 6:46
  measuring and addressing the conditions that lead to them.
• 6:49
  The underlying principle is that safety is fundamentally the
• 6:51
  presence of safeguards, not the absence of incidents.
• 6:55
  Now, what I find more interesting is a hazard in
• 6:57
  Hagar. It's classified if it's high
• 7:00
  energy if it involves more than 1500 joules of physical energy.
• 7:05
  As research indicates, this level is most likely to result
• 7:07
  in a sieve. So while the current study I
• 7:10
  discussed before suggested maybe 2000 joules for the magnitude of
• 7:14
  energy is something that's high energy and more likely to be a
• 7:17
  sieve, the hiker adopts 1500 joules.
• 7:21
  Also, Hiker incorporates the principles of hop so human and
• 7:24
  organisational performance, acknowledging that even
• 7:27
  experienced employees make mistakes.
• 7:29
  Therefore, controls against life threatening hazards must be
• 7:32
  effective even when human performance variability is
• 7:35
  present. Human error.
• 7:38
  They suggest that for a safeguard or some sort of
• 7:40
  control to qualify as a direct control, it must meet three
• 7:44
  criteria. It must be specifically targeted
• 7:47
  to high energy sources of concern.
• 7:50
  It must effectively mitigate exposure to the high energy
• 7:53
  hazard when properly installed, verified, and used.
• 7:57
  This means it either eliminates the energy or reduces exposure
• 8:00
  below the 1500 Joule sieve threshold for thereabouts.
• 8:05
  If it's not installed or used correctly, it's not considered a
• 8:08
  direct control. It's considered absent direct
• 8:10
  control. It must remain effective even if
• 8:13
  there's an unintentional human error during the work.
• 8:17
  This critical criterion means that controls like situational
• 8:20
  awareness, science or training aren't instead of direct
• 8:23
  controls because they're vulnerable to human performance
• 8:26
  variability. So some limitations based on the
• 8:29
  study, not HIGA. The computation of energy
• 8:32
  intensity magnitudes can be quite intensive for
• 8:36
  practitioners. It's also a little bit limited
• 8:38
  by the vulnerability of the human body parts.
• 8:41
  It makes it really hard to sort of predict.
• 8:43
  But remember, 1500 to 2000 joules thereabouts is more
• 8:46
  likely to result in sifts. Now, this study focused
• 8:50
  specifically on motion and gravity hazards because they
• 8:53
  were more readily calculable, but other energy sources where
• 8:57
  chemical, biological, electrical, radiation might
• 9:00
  require different assessments. Now I think your average
• 9:03
  engineer can't help calculate though.
• 9:06
  There's a few other limitations, but All in all I think it's a
• 9:09
  really useful technique. Getting back to energy thinking
• 9:13
  really strongly aligns with Hatton Junior's work from the
• 9:16
  1950s onwards, and you might actually already be pretty
• 9:19
  familiar with energy based thinking given the popularity of
• 9:23
  the energy wheel today. This study is simply diving into
• 9:26
  the more specifics, the magnitudes and intensities of
• 9:29
  that energy. That's it on Safe.
• 9:32
  As I'm Ben Hutchinson, please help share, rate and review and
• 9:37
  checkout Safety insights.org for more research.
• 9:40
  Finally, feel free to support Safe As by shouting a coffee
• 9:44
  link in the show notes I.