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Discover: Not just for chairs, using the science of ergonomics to make safer workplaces

How forensic ergonomics are used to investigate on-the-job injuries

When you hear the term “ergonomics” what comes to mind? Comfy car seats? Your uncomfortable computer set-up? Yes, these involve ergonomics, but its application is so much broader. The science of ergonomics has been applied to investigations of accidents ranging from nuclear power plant catastrophes, to plane and train crashes, to fatal and critical injuries in the workplace. 

The Three Mile Island nuclear power plant disaster in 1979 is a worst-case example of the consequences of poor ergonomic design. The displays in the plant didn’t clearly show the plant operators that something was wrong – or what corrective actions had to be taken. On top of this, the incident began around 4 a.m., when the plant operators were at the low point of their daily (circadian) rhythms, which can affect performance. (This is true for all of us. Another low point is 2-5 p.m., which is why we often feel tired in the afternoon.). 

Good ergonomic design can help account for this. Poor ergonomic design brought us to the brink of a total nuclear meltdown.

What exactly is ergonomics?

My favourite definition of ergonomics is from Webster’s dictionary. It is “the study of the mental and physical capacities of persons in relation to the demands made upon them by various kinds of work.”

The ultimate goal of ergonomics is to improve our efficiency, health, safety and comfort. It does this by optimizing the relationships between people, the tasks they perform, the equipment they use, and the environments in which they work and live. We don’t all work in nuclear power plants, but a mismatch between people and their tasks can cause fatigue and job dissatisfaction. It can also result in mistakes that damage equipment, products, and property, or injury to people. Ergonomics truly touches every facet of our lives.

Being an Ergonomic Investigator

Before I get into ergonomic investigations, here’s a bit of my background. I studied kinesiology and systems design engineering, which gave me a grounding in the sciences related to human performance and how to apply them to work/person systems. 

During two co-op placements at Falconbridge (now Glencore), I worked doing physical demands analyses of jobs in the mill and smelter to help with accommodating injured workers. Many workers I talked with wished they had known more safe and ergonomic methods to do their jobs when they were younger — they now had work-related injuries. This is what convinced me to get into a career in ergonomics.

My 32-year career in occupational health and safety involved assisting workplaces with using ergonomics to improve workplace conditions by getting a better fit between the worker and the tasks and equipment they used in their jobs. It also involved investigation of workplace issues (injuries, complaints) related to ergonomics. 

Ergonomists like me rely on the findings and methods from a number of scientific fields, such as: 

  • Anthropometry: the study of individual variations in dimension. How well does a person fit into their environment?
  • Biomechanics: the physics of human movement. What loads and forces can a person handle? 
  • Physiology: the mechanisms of bodily function. What temperatures and/or workloads can a person handle?
  • Psychology: human behaviour. What are the mental and/or perceptual demands of a task?

Common Ergonomic-Related Injuries

The most common injuries linked to poor ergonomics are musculoskeletal disorders (MSD). These can happen to anyone. They include conditions such as back or tendon injuries that can result if the task you’re doing exceeds your physical capabilities. 

Unfortunately, there a number of fatal and critical injuries that occur on the job. When workplaces or government health and safety agencies need to figure out how a workplace injury happened, they increasingly turn to the field of ergonomics and its related sciences. The ultimate goal of these investigations is to help prevent future incidents. 

Ergonomic investigation teams act like detectives: they observe workplace conditions, interview witnesses, review procedures and training, and research standards and good practices. Some ergonomics analysis is usually required, for example, establishing lines-of-sight from an operator’s position in a piece of mobile equipment (Image No. 2), or calculating the effects of balance on a ladder while a load is being handled (Image No. 3). 

Two real-life investigations I helped on

Mining: A worker was loading materials into a small tractor parked along a curve on an underground ramped passageway. An underground loader (scooptram) travelling down the ramp struck the worker and tractor, fatally injuring the worker. 

The investigation team analyzed the operator’s view and the lighting in the area. We found that the scoop operator’s line of sight was blocked by a part of the scooptram and that an overhead light in the passageway masked the light from a strobe on the tractor meant to reflect off the roof and walls. Simply put, the scoop operator could not have seen either the worker or the light from the tractor’s strobe light. Due to investigations of this and similar incidents, a number of steps have been taken over the years to help prevent this kind of incident from happening again. 

Examples of these steps include:

  • Inquest recommendations for research into line-of-sight and training of operators and workers regarding the hazard;
  • Implementation of high visibility clothing, more effective worker location markers, and vehicle markings/lighting. For example, there are now bright blue lights that shine into the upper corners of a passage to better show vehicle location (See Image No. 4);
  • Improved communication regarding vehicle and worker locations;
  • Changes to underground loaders to improve the operator’s view; and
  • More information available on the lines-of-sight around mobile equipment (See Image No. 2).

Researchers from Laurentian University’s Centre for Research in Occupational Safety and Health (CROSH) do research and assist with recommendations and education on line-of-sight. You can learn more here.

Construction: A young worker on his first day of work was carrying heavy bundles of shingles up an extension ladder leaned against the edge of a roof. He supported a single bundle on his shoulder during each ladder climb. He carried several bundles up and placed them on the roof in front of the ladder. As this area became filled, he then leaned sideways to place the bundle beside the others. The ladder slid sideways, and he fell, breaking his femur. 

A biomechanics program (Image No. 3) was used to estimate the worker’s handling demands and stability. We found that the amount of weight lifted and how it was moved along the roof caused the ladder to shift and the worker to fall. The lessons learned from this investigation helped improve shingling practices in the construction industry: There is now greater use of boom trucks, conveyors and ladder lifts to place shingles on a roof. 

These are just a couple of examples of how ergonomics and its related sciences can be used to investigate injuries and contribute to prevention. Ergonomics can be applied in the design of the tasks and tools we use every day, making us more comfortable, efficient, and safer, both at work and at home. Personally, I am grateful for a career that allowed me to help people apply ergonomics in the improvement of their safety and comfort.

For more information on the Three Mile Island incident, read on here

For more information on MSD and its prevention, click here.

If you’re interested in some injury statistics for the Northern Ontario-related industries of mining and forestry, check out these resources from Workplace Safety North.

Peg Scherzinger is an ergonomist and an affiliate with the Centre for Research in Occupational Safety and Health (CROSH) at Laurentian University. Recently retired from the Ministry of Labour, she investigated workplace fatalities and critical injuries. 

This article was prepared with the assistance of Tobias Mankis, the science communication officer with CROSH, and a graduate of the science communication program at Laurentian University.