Ergonomics In The Workplace
(Provided by the US Center For Disease Control)
Contrary to popular belief, sitting, which most people believe is relaxing, is hard on the back.
Sitting for long periods of time can cause increased pressure on the intervertebral discs - the
spongy discs between the vertebra. Sitting is also hard on the feet and legs. Gravity tends to pool
blood in the legs and feet and create a sluggish return to the heart.
The following recommendations can help increase comfort for computer users: --> "Dynamic sitting", don't stay in one static position for extended periods of time.
--> When performing daily tasks, alternate between sitting and standing or take small walking
breaks throughout the day.
--> The chair back should have a lumbar support
--> Adjust height of backrest to support the natural inward curve of the lower back.
--> It may be useful to use a rolled towel, lumbar roll or cushion to support the low back.
--> The angle of the back rest is subjective but the trunk and upper legs should form an angle
between 90 to 115 degrees.
--> Adjust height of chair so feet rest flat on floor
--> Sit upright in the chair with the low back against the backrest and the shoulders touching the
--> Thighs should be parallel to the floor and knees at about the same level as the hips.
--> Back of knees should not come in direct contact with the edge of the seat pan. There should be
2-4 inches between the edge of the seat and the back of the knee.
--> Arm rests should be removable and the distance between the arm rests should be adjustable.
--> Adjust height and/or width of armrests so they allow the user to rest arms at their sides and
relax/drop their shoulders while keyboarding.
--> Don't use armrests to slouch. Also, chair arms should not noticeably elevate your shoulders or
force you to move your arms away from your body to use them.
--> Elbows and lower arms should rest lightly on armrests so as not to cause circulatory or nerve
--> Use a footrest when attempts to adjust your chair and the rest of the workstation fail to keep
your feet on the ground.
--> Ensure that you have some space (2-3") between the top of your thighs and the underside of
--> Have enough space under your work surface so that you can pull your self all the way up to the
edge of the desk with room for your legs and knees to fit comfortably.
We've discussed the chair, work surface height adjustments, monitor, keyboard, the mouse and now
Improper lighting is a major contributing factor in visual discomforts including eyestrain,
burning or itching eyes, and blurred or double vision.
The lighting in most office environments is too bright for optimal VDT screen viewing. Suggestions
for reducing the illumination may be to remove 2 bulbs in a 4-bulb fluorescent fixture, removing
the bulbs in every other fixture, or turning off overhead lights altogether.
Desk lighting is better than overhead lighting for reading or printed copy.
The following recommendations can reduce eyestrain and eye fatigue:
--> Close drapes/blinds to reduce glare.
--> Adjust lighting to avoid screen glare --the light source should make a 90 degree angle with
low watt lights rather than high.
--> Avoid intense or uneven lighting in your field of vision.
--> Place monitor at 90 degree angle to windows.
--> Reduce overhead lighting.
--> Use indirect or shielded lighting when appropriate.
--> Walls should not be painted with a reflective finish or high gloss paint.
--> Use a glare screen or monitor shield to reduce glare from overhead lighting.
NOTE: IN THE OFFICE OR WHILE AT HOME, A DOCKING STATION IS RECOMMENDED TO PROVIDE ADJUSTABILITY.
Maintaining neutral postures will reduce stress and strain to your musculoskeletal system.
--> It is recommended to take a break every 20 to 30 minutes.
--> Maintain a comfortable viewing distance from your screen; about 18-30 inches.
--> Keep your head and neck in a neutral posture; avoiding any excessive neck flexion or rotation.
--> Angle the screen so that it is perpendicular to the line of sight, if the lighting permits.
--> Position the keyboard at elbow height keeping your wrists straight while keying.
--> Adjust the table height, chair height and keyboard angle to maintain neutral wrist postures.
--> Remember: if you raise your chair use a footrest to support your feet.
--> When seated your hips should be slightly higher than your knees.
--> If you are seated in a side chair or couch, a pillow may support your arms while keying. This
will help maintain neutral arm, wrist, and hand postures.
--> Attach an external mouse instead of using the small constricted touch pad or trackball.
--> Clean the screen regularly using manufacturer recommended appropriate antistatic cleaning
--> The hands and wrists are to be kept in a straight wrist posture when typing and should not be
resting on a palm rest, table, or lap while typing.
--> Wrist and palm rests are designed to provide support during breaks from typing.
Transporting the Computer
--> While transporting your laptop:
--> Eliminate unnecessary baggage from your briefcase.
--> Carry your laptop in a case with a padded shoulder strap and handle.
--> Frequently shift hands or shoulders to balance the load.
--> Use a wheeled luggage cart when possible.
We've discussed the chair and work surface height adjustments, now the computer monitor should be
placed so the top of the screen is at or just below eye level when seated in an upright position.
The following suggestions can help prevent eye strain, neck pain and shoulder fatigue while using
a computer workstation:
--> Clean the surface of the viewing screen.
--> Adjust brightness and contrast to optimum comfort.
--> Position the monitor directly in front of you to avoid excessive twisting of the neck.
--> Position the monitor at a comfortable viewing distance, approximately 18-30 inches from the
--> Position monitors at right angles from windows to reduce glare.
--> Close window blinds as needed to reduce glare from sunlight.
--> Position monitors away from direct lighting which creates excessive glare or use a glare
filter over the monitor to reduce glare.
--> Adjust the monitor tilt so that ceiling lights do not reflect on your screen.
--> If a document holder is used, it should be placed at approximately the same height as the
monitor and at the same distance from the eyes to prevent frequent eye shifts between the monitor
screen and reference materials.
--> Get regular eye check-ups.
--> Adjust as needed for larger screens. You may need to sit farther away and increase the font
size to take full advantage of the larger screen.
Bifocal and trifocal wearers have to pay particular attention to the placement of their monitor.
Wearers of bifocals and trifocals often unknowingly tilt their heads backwards so they can read the
screen through the lower portion of their glasses. This could lead to neck, shoulder, and back
Potential solutions include either lowering the computer monitor or purchasing glasses designed
specifically for working at the computer.
Working at the computer is very fatiguing on your upper extremities as well as your eyes. It is
important that breaks from working at the computer be taken every 20 to 40 minutes in order for your
body to rest and recover.
Taking a 3 to 5 minute break does not mean you have to stop working. Other activities such as
talking to a co-worker, making copies, filing, etc. could be done during breaks from typing.
It is also important to change positions periodically. Sitting in one position or leaning on your
arms for an extended period of time can interfere with circulation.
MOUSE, TRACKBALL, OR OTHER INPUT DEVICE
We've discussed the chair, work surface height adjustments, monitor, keyboard and now the mouse.
The mouse is present in virtually every office environment. Hand versions are designed
specifically to the contours of either the right or left hand.
--> Placing the mouse, trackball, or other input device too far away, too low, or too much on one
side can cause shoulder, wrist, elbow, and forearm discomfort.
--> Placing the input device directly in your reach zone offers natural comfort and maximum
--> Do not bend your wrist upward.
--> Make sure you are sitting high enough for the workstation to be slightly below elbow height so
your hand rests on the mouse.
--> Mousing demands surface stability; if used on a keyboard tray, the tray should not wobble or
--> A trackball has a ball that you manipulate with your fingers requiring the use of different
muscle and tendon groups than a mouse, and can add variety to your capabilities.
--> Some trackball designs, however, may cause injury to the area around your thumb, which
stretches and reaches to maneuver the trackball.
--> Test different models of input devices.
--> Consider the shape and size, comfortability, ease of operation, and special features that
might make your job easier.
In addition to the mouse and trackball, a variety of other input devices are available. Consider
task requirements and any physical limitations.
--> Touch pads allow you to move the cursor on the computer screen by gliding your finger across a
--> Unlike the mouse, trackball, or other pointing devices, touch pads have no moving parts to
clog or break, so they never require disassembly or cleaning.
--> Touch screens allow you to point directly at objects requiring little or no training, and are
faster than pointing devices, while requiring no extra work surface.
--> Disadvantages of touch screens include arm fatigue, smudges, optical interference, and
--> Voice input allows you to "talk" to your computer. Currently these programs understand and
respond to natural speech delivered at rates up to 160 words per minute.
--> Pen-like devices use pressure, light, electromagnetic disruption, or radio frequencies to
enter information through contact with the computer screen or horizontal pad.
--> A pen pad requires as much room on the work surface as does a mouse.
--> If pen technology is used on a horizontal pad, a workstation is required, and adequate
non-glare lighting for both it and the computer screen.
Standard desks and workstations cannot accommodate everyone's needs. Someone taller may need to
have his or her work surface raised; a shorter person may need a footrest or other accessories.
Adjustable furniture is suggested where people share or use the same workstation.
-->Organize the desktop so that frequently used objects are close to avoid excessive extended
-->The work surface should have a matte finish to minimize glare or reflections.
-->The area underneath the desk should be uncluttered to accommodate the user's legs and allow for
-->If a fixed-height desk is used, adding a keyboard tray that adjusts vertically is suggested.
-->A footrest should be used if the feet do not rest flat on the floor.
-->Use a headset or speaker phone to avoid neck and shoulder discomfort if you use a phone
-->Place the phone on the side of your non-dominant hand (i.e., left side if right-handed, right
side if left-handed)
-->Position your desk lamp so that it illuminates source documents without causing either glare on
the computer screen or direct illumination to your eyes.
-->A document holder should be used if documents are referred to during keying. The document
-->Be stable and adjustable (height, position, distance, and angle of view).
-->Support your document on either side of the monitor.
-->Be at the same distance from your eyes as the display screen to avoid frequent changes of focus
and you should be able you to look from one to the other without moving your neck or back.
The work area should be large enough to accommodate you, allow the full range of motions involved
in performing required tasks, and provide room for the equipment and materials that make up the
--> Use a headset for lengthy or frequent telephone work.
--> Place the items you use most frequently directly in front of you.
--> Avoid overcrowding computer work areas.
To see how you should be set up at your desk, please visit IBM's site:
Ergonomics: Page 1 || Page 2 || Page 3 || Page 4
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