A Day To Honour The Fallen Worker

 

Today is the National Day of Mourning for those killed on the job here in Canada. Every day, an average of 2 workers are killed on the job, with an average of 835 workers passing away every year. This day is a raw reminder of how far we have to go in order to make our workplaces safe not only from ergonomic issues, but from threats of potential fatalities.

As far as posting on this blog goes, it has slowed considerably lately due to the commencement of my new research job. Things were busy this past week, but as I adjust to my schedule, I will be posting more often. Expect a post early next week!

The Ergonomist's Toolbox: The NIOSH Equation

This week, I have looked back upon the posts of weeks past, and since there is little distinguishing previous Sunday Spotlights, and mid-week posts such as the one on hand tools just recently, I have decided to discontinue that series.

However, I would like to introduce a new series of posts to take Spotlight's place: The Ergonomist's Toolbox. These posts will focus on online web resources that ergonomists and human factors professionals can use to help them to complete their work tasks.

One task common to ergonomists involves establishing the level of risk posed to workers by the materials that they lift and lower on a daily basis. The tool most commonly used to assess manual material handling risk is the NIOSH equation. Some professionals use tables to calculate the Recommended Weight Limit (RWL) and the Lifting Index (LI); this can be tedious and time-consuming.

Fortunately, some altruistic people out there in the ergonomics community have created tools that only require the input of relevant values, computing the desired statistics in seconds:


http://www.ohcow.on.ca/downloads/niosh91.exe -- A simple, yet effective NIOSH equation program. Highly recommended.

http://www.cdc.gov/niosh/94-110.html -- Detailed, in-depth information on the particulars of the equation from the people who created it.

http://www.ccohs.ca/oshanswers/ergonomics/niosh/assessing.html -- The "Coles Notes" version of the previous link, simplifying the explanation of the equation for those put off by jargon.


If there are any lurkers out there with any other resources they'd like to suggest, please feel free to comment. If you have any feedback on this blog thus far, also feel free to comment as well!

Proper Tool Usage: Heights, Surfaces, and Tool Types

After focusing on precision and power grips during the last two Spotlights, it feels only natural to dedicate the next few posts on how to properly use hand tools in varying circumstances; this post will focus on varying surfaces and heights. Depending on the intended usage, grips that make ergonomic sense in some applications may put the user in an awkward position in another application. For example, using a power drill that has a pistol-grip setup makes sense when working on a wall but it causes extreme wrist flexion if you attempt to use it on a high horizontal surface, such as a table.

AVOID:

- Using inline-handled tools on vertical surfaces, such as walls.

- Using inline-handled tools on horizontal surfaces, such as tables, when the surface is below elbow height.

- Using pistol-grip tools on horizontal surfaces above waist height.

- Using pistol-grip tools at any height other than elbow height, when working on vertical surfaces.


DO:

- Use inline tools on horizontal surfaces at elbow height.

- Use pistol-grip tools on vertical surfaces at elbow height.

- Use pistol-grip tools on horizontal surfaces below waist height.

Sunday Spotlight: The Precision Grip

 
Last week we focused on the power grip for the Sunday Spotlight; tonight, we shall examine its companion, the precision grip.

The precision grip is used by workers when accuracy, detail, and fine movements are necessary to complete a task. The precision grip is performed by gripping the tool in question between the thumb and the forefinger. There are two types of precision grip: an internal precision grip is performed when the tool handle lies inside the palm of the user's hand (e.g. using a knife), and an external grip is performed when the tool handle lies outside the palm (e.g. writing with a pen).

The worker using a precision grip must take care to only use it when low forces are required to use the tool in question (< 2 lb of force), as the muscles used during a precision grip are small and fatigue easily, therefore overstressing those systems can quickly lead to a injury.

How-To: Eliminating Non-Neutral Wrist Postures

Continuing on with our series of posts dedicated to eliminating non-neutral postures from your workplace, today the wrist gets our special treatment. Famous for being the structure of the body (next to the back) that sprung ergonomics to mainstream recognition (think Carpal Tunnel Syndrome!), and you'll see why it's vital to ensure that this area of the body is subjected to as little stress as possible.

There are 3 major positions that the wrist enters into awkward alignments:

1) Wrist Flexion (wrist "down-bending")
2) Wrist Extension (wrist "up-bending")
3) Wrist Deviation (wrist "side-bending")


WRIST FLEXION

Problem: The objects being accessed can only be acquired below hand level, forcing the operator to flex their wrist (e.g. reaching into a part bin for a screw)

Solution: Eliminate barriers that obstruct the wrist, and/or ensure the surface is high enough to avoid wrist flexion. Examples of this include cut-outs in part bins, and adjustable height work surfaces.


WRIST EXTENSION

Problem: The objects being accessed can only be acquired above hand level, forcing the operator to extend their wrist (e.g. typing on an improperly adjusted keyboard). This awkward posture is also caused by pushing objects that lack proper handles, forcing operators to put their wrists into extension to apply the maximum possible force, and by tool handles that are inappropriate for the surface being worked on.

Solution: Adjust work surfaces so that objects can be accessed with the wrist in neutral position. Ensure carts and other frequently pushed items have handles affixed to them. Use tool with pistol-grip handles for vertical surfaces, and inline handles for horizontal ones.


WRIST SIDE-DEVIATION

Problem: The objects that are being accessed are off-centre of the hands, forcing the operator to side-bend their wrists. Wrist side-bending is also performed when tearing receipts from cash registers, putting stress on the wrist over time.

Solution: Ensure work object is presented in front of the operator before aquiring it. If the speed of a conveyor causes the operator to perform this awkward posture, slow the conveyor, reduce the flow, or enable the operator to stop their section of the conveyor if the workload gets too heavy. As for tearing register receipts, acquire cash registers with the auto-receipt cutter, eliminating the need for the operator to do the tearing task.

Sunday Spotlight (On Monday): Power Grips

The focus of this week's Sunday Spotlight (written today due to a sudden personal engagement that came up yesterday) is not on an object, but rather on a technique. Power grips refers to a grip where the hand wraps fully around a handle of a tool, allowing the user to express more power to the tool being used, hence the name.

By using larger muscles in the worker's arm, they are able to impart more power to the tool for less effort on the muscle's part, greatly reducing muscular fatigue in the arm. One disadvantage of the power grip is that it lacks the precision and accuracy of the precision grip. If the task requires more than 2 lbs of force though, a power grip should be used, and accuracy requirements on the part of the user be reduced through engineering measures.