August 2017 Newsletter:

�What�s wrong with this picture?� - Ergonomic Hazards Edition

The first step in any ergonomic task evaluation is identifying the hazards that are present; this is key so you can then gather the data you need to determine the degree of risk. Without this information, you cannot begin to prioritize areas of improvement, which really will hinder the ergonomic change process.

The key elements that ergonomists look for (although there are more!) are:

  1. Force: is the worker manipulating heavy objects or accelerating quickly? Force hazards could resemble large and heavy objects that the worker lifts, or even swinging a sledgehammer during drywall demolition.
  2. Posture: how much deviation is there between the worker�s body position and a relaxed, neutral position? The greater the difference, the more effort required by the worker�s muscles, which can lead to fatigue, discomfort, and injury. For example, dentists and dental hygienists often lean over their patients with no support for their back muscles which increases injury risk.
  3. Repetition: how often does a movement occur? This often appears in tandem with other hazards but can be a hazard on its own. For example, assembly workers� wrists may not move to their end range of motion, but the work pace means that the movements are very repetitive, which can predispose workers to injury.
  4. Duration: for how long does the worker do this per hour/shift? This idea considers the idea cumulative exposure. An example could be a snowplow operator working during a blizzard; sitting in a truck for eight or more hours introduces several ergonomic concerns.

One thing to keep in mind is that hazards on their own are not always a problem. For example, lifting a 30-lb. box with good posture once per shift may not be an issue. It is when you start to combine hazards that you create more problems. That same 30-lb. box lifted five times a minute (i.e. higher repetition) with poor posture is certainly going to increase your risk!

Here is a real-life example to help you get a handle on the basics.

Anyone who has painted their house knows that is tiring! Let�s examine what hazards are present in this task:

  • Force: the amount of force required to paint walls is minimal: paint rollers don�t weigh more than a few pounds and, as a result the risk associated with force is low.
  • Posture: looking at this picture, we can see that the shoulder is moving through a large range of motion and that his posture is deviating from a relaxed and neutral position. This forces the muscles of his arm and shoulder to work hard, increasing injury risk.
  • Repetition: there is relatively high repetition rate when rolling paint as the painter will constantly move up and down across a designated area to maximize coverage.
  • Duration: assuming this is his full time job, he likely paints 30-40 hours per week.

When you add these factors together, it�s plain to see that this painter�s job puts him at a risk of shoulder injury with potential other risk factors present for his wrists and elbows.

And there you have it! A glimpse into what an ergonomist is looking for while they are onsite evaluating a job to determine risk of injury. Identifying this risk can become more complicated depending on the complexity of the job and the variation of different tasks that are performed.

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