Your reach envelope is the work area you are able to access without excessive reaching. This area is specific to every individual and depends on body size, but generally the normal reach area is about 18 inches from the body. The maximum area is typically 18 – 24 inches. This area may be less for people with shorter arms and more for people with longer arms.
Excessive reaching can increase torque (force) around a joint. The further you lift a weight away from the body the more force is exerted in order to handle the weight. Increased force may increase the risk for injury. Awkward postures also affect circulation.
Computer input devices, phone, writing instruments, laboratory instruments, measurement tools and other frequently used items should be placed within the "normal" area of your reach envelope (see figure above). A common mistake is mouse use beyond the normal reach envelope. A mouse/keyboard tray, a different input device or a mouse bridge can be used to bring the mouse within normal reach envelope. Work in fume hoods also is commonly performed outside the normal work envelope due to safety hazards. Proper personal protective equipment and using the best tools for the job can reduce reach distances. (Adobe Acrobat Reader required)
The computer screen should be placed at or beyond the maximum area of the reach envelope. This distance is typically arms length away from your body. If you have problems viewing the computer screen at any distance, ask an eye doctor about computer glasses. More information on computer eyeglasses can be found at http://businternal.lanl.gov/bus5/jit/glasses.htm online.
Large binders and other heavy items should be placed outside the reach envelope so that you do not reach for these items while seated.
A common mistake is to place the printer at the maximum area in the reach envelope. Printers, scanners and reference materials such as books, should be placed outside the reach envelope so that you have to stand (a mini-break) in order to access printed documents and other materials. The postural change is good for the body (unless you have medical restrictions that do not allow for this).
For more information or questions about reach envelopes, write to ergonomics@lanl.gov by electronic mail.