Dec 2011: I lost the original page I had designed for this early in 2011. I appealed to my viewers to let me have their copies or details of the page. I did not get any response. But, I have put together a new version from memory. If someone feels I have left out anything, please let me know.
-- Prof Krishna

The Asian backbone has been shown to take an average of about 500kg force on a regular basis, although occasiona loads may go up to about double that value.

How much do your workers carry on a regular basis, any idea?

{HINT: Cement bags generally weigh 50kg, except in a few coun-tries like Australia, where by law they are limited to 20kg)

How about holding an object standing vertically?
Even standing in one position holding a 25kg load at a distance from the body, and moving and/or rotating it about one's vertical axis, puts more load on the spine -- meaning that the load should be reduced if the activity is on a regular basis.

On the basis of extensive research, the National Institute of Occupational Safety and Health of USA had come up with an equation in 1981; from the experience gained and with additional data, a revised equation was released in 1994. This is widely used around the world as the "REVISED NIOSH LIFTING EQUATION".

I did two things to spread this information in Singapore:
1. Develop a spreadsheet for the NIOSH(slightly simplified) Equation. You can get it by clicking on the spreadsheet thumbnail at LEFT.
2. Write a paper on it, with an example extending use of the equation for risk assessment, published by IE(S), which you can by clicking at RIGHT.

1. “Getting to Grips with Manual Handling - A Short Guide”, Health and Safety Executive, U.K., 20 p, 2004. Access by clicking HERE. [An excerpt is given below.]
2. Waters, Thomas, Vern Putz-Anderson, and Arun Garg. “Applications Manual for the Revised NIOSH Lifting Equation”, DHHS (NIOSH) Publication No. 94-110, U.S. Dept. of Health and Human Services, National Institute for Occupational  Safety and Health, Cincinnati, Ohio, 164 p, Jan. 1994. Access by clicking HERE.
3. “NIOSH Lifting Equation” (with tables and calculator), web-page by Canadian Center for Occupational Health and      Safety (CCOHS). Access by clicking HERE. http://www.ccohs.ca/oshanswers/ergonomics/niosh/calculating_rwl.html

We all make mistakes now and then ... but now, mistakes can travel around the world faster than good news!

And remain undiscovered, to be downloaded and used by God knows how many.

Then comes along someone who accidentally or by deep interest in and analysis of the material, discovers the error.

Goes to show how careful we must be when we take stuff from the internet as a resource for our work!

I was lucky to find some-one's error. If you find any in mine, do let me know!

-- Prof Krishna

There is also the small visual problem in this example that the loads are shown to imply that the ratio 10:1 arises from the ratio of horizontal distances of the picked-up load and the resulting spine force (shown vertical, incorrectly) from the fulcrum. Actually it is the moment caused by the lifting of the load and the resisting moment developed by the vertebral segment, as shown in the top figure. -- N. Krishnamurthy
Folks ask me how (now that they know that their Asian workers should not carry more than 25kg) to avoid the workers carrying 50kg cement bags. Answer shortly. -- NK