Requirements Of Working Height
Once employees adjust their chairs to the comfort requirements of their heights, they then will be seated at differing heights relative to their work surfaces, typewriters or terminal keyboards.
If these keys or surfaces are too high, then the users are forced to raise their
arms. Many shorter
individuals raise their arms from the shoulders, almost like having a constant
"shrug". This uses muscles
across the top of the shoulders and at the base of the neck, and it often takes very
little time before
discomfort is felt.
At a properly positioned work surface, terminal keyboard, or typewriter, the height of the surface or keys will be at elbow height, when the individual drops his arms to his side while sitting. At this height the employee may work in an upright, yet comfortable sitting posture, with the forearms at right angles and parallel to the floor in a relaxed working position.
Clearly the requirements of sitting and working height apply to all office employees no matter what their job function. Yet most researchers of European data regarding adjustable computer terminal tables appear to be totally unaware that many of the countries from which the data come have been using height adjustable desks for all job functions for over twenty years.
In fact in some of the countries they are required by law. It is easy to understand how adjustable terminal tables were quickly developed in such an environment, immediately after computer terminals went on the market and long before the potential user problems were even recognized in North America.
In a handbook prepared by the Missile System Division Human Engineering staff at Lockheed Missiles and Space Company, Sunnyvale, California which is intended primarily as an aid in solving the Human Engineering and industrial designs problems encountered in the design of electronic checkout equipment, some very revealing factors turn up.
Although the information presented is based on design problems experienced during the development of the Polaris/Poseidon missiles it is considered applicable to the design of work areas for other types of electronic equipment.
"An efficient man-machine relationship can be achieved only by taking the body measurements of operations and maintenance personnel in account in the design process."
The body dimensions (some of which are quoted below) represent the 5th and 95th percentile body measurements for the adult male population in the U.S - we can safely assume similar results in the Canadian population.
When considering that the average values shown above are for males and considering again that the values for the female population would cover a similar range, but due to the fact that females generally are physically smaller it suggests itself to question the wisdom of a standard of 29.5" high work surface (desk top) which is the current standard height in North America when 29.7" is considered maximum height for a man.