Today we’re answering a request for research on the ideal placement of products to reduce potential hazards to employees. You can read the question below:
I’m looking for documents to support that storing product below the knee and reaching above the shoulder is hazardous to the employee. I can’t find research to support my request for change. Thanks for your help!
We reached out to Marty Frame, who has many years of experience in performing industrial, warehouse and manufacturing ergonomics assessments, for her thoughts:
The issue isn’t that you can’t store objects below the knees or above the shoulders, but that you should consider the weight of the objects. Workers are strongest when lifting in their power zone which is between the shoulders and knees. Therefore, the heaviest objects should be stored in this zone, with the next heaviest below the knees and the lightest above the shoulders. Rationale for this is based on bio mechanical, pyschophysical and physiological principles. The NIOSH lifting guide provides rationale. if you look at the vertical multiplier, it is 1 (meaning it does not affect the load constant) at a distance of 30 inches from the floor and and decreased to .78 at floor level and .70 at 70 inches. ((greatest affect on load constant)
Another way to rationalize the placement of the objects is to refer to the Liberty Mutual Material Handling Guidelines These Guidelines tell you what % of the male or female population can safely perform a lift of a certain weight. Referring to these Guidelines you can see that more workers can perform a lift of a certain weight when the lift is between shoulder and knuckle height as opposed to above shoulder height or below knuckle height. I am attaching two web sites that you can reference the NIOSH and Liberty Mutual Guidelines.
Do you have any experience in dealing with this or similar issues? Let us know in the comments!