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Ergonomic
Guidelines for arranging a Computer Workstation
10 tips for users
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Creating a good ergonomic working arrangement is important to protecting
your health. The following 10 tips are a brief summary of those things that
most ergonomists agree are important. If you follow the 10 tips they should
help you to improve your working arrangement. However, every situation is
different, and if you can't seem to get your arrangement to feel right or
you are confused about some of the following recommendations you should
seek professional advice.
10 tips for a good ergonomic workstation arrangement |
Work through the following 10 steps to help you decide on what will be
a good ergonomic design for your situation:
- How will the computer be used? If it's one person then the arrangement
can be optimized for that person's size and shape, and features such as
an adjustable height chair may be unnecessary. If it's several people,
you will need to create an arrangement that most closely satisfies the
needs of the extremes, that is the smallest and tallest, thinnest and broadest
persons. Also think about:
- How long will people be using the computer? If it's a few minutes
a day then ergonomic issues may not be a high priority. If it's more than
1 hour per day. you need to create an ergonomic arrangement.
- What kind of computer will be used? Ergonomic guidelines for
computer workstation arrangements assume that you will be using a desktop
system where the computer screen is separate from the keyboard. Laptops
are growing in popularity and are great for short periods of computer work.
Guidelines for laptop use are more difficult because laptop design inherently
is problematic - when the screen is at a comfortable height and distance
the keyboard isn't and vice versa. For sustained use you should consider
purchasing either an external monitor, an external keyboard, or both and
a docking station.
- What furniture will you use? Make sure that the computer (monitor,
CPU system unit, keyboard, mouse) are placed on a stable working surface
(nothing that wobbles) with adequate room for proper arrangement. If this
work surface is going to be used for writing on paper as well as computer
use a flat surface that is between 28"-30" above the floor (suitable
for most adults). You should consider attaching a keyboard/mouse tray system
to your work surface. Choose a system that is height adjustable, that allows
you to tilt the keyboard away from you slightly for better wrist posture
(negative tilt), and that
allows you to use the mouse with your upper arms relaxed and as close to
the body as possible.
- What chair will be used? Choose a comfortable chair for the
user to sit in. If only one person is using this the chair can be at a
fixed height providing that it is comfortable to sit on and has a good
backrest. If more than one person will be using the computer, consider
buying and a chair with ergonomic features.
- What kind of work will the computer be used for? Try to anticipate
what type of software will be used most often.
- Word processing - arranging the best keyboard/mouse position
is high priority.
- Surfing the net, graphic design - arranging the best mouse position
is high priority.
- Data entry- arranging the best numeric keypad/keyboard is a
high priority.
- Games - arranging the best keyboard/mouse/game pad is a high
priority.
- What can you see? Make sure that any paper documents that you
are reading are placed as close to the computer monitor as possible and
that these are at a similar angle - use a document holder where possible.
The computer monitor should be placed:
- directly in front of the user and facing the user, not angled to the
left or right, to avoid too much neck twisting. Also, whatever the user
is working with, encourage him/her to use the screen scroll bars to ensure
that what is being viewed most is in the center of the monitor rather than
at the top or bottom.
- it should be centered on the user so that the body and/or neck isn't
twisted when looking at the screen. However, if you are working with a
large monitor and spend most of your time working with software like MSWord,
which defaults to creating left aligned new pages, and your don't want
to have to drag these to more central locations, try aligning yourself
to a point about 1/3rd of the distance across the monitor from the left
side.
- it should be placed at a height that doesn't make the user tilt their
head up to see it or bend their neck down to see it. When your seated comfortably,
a user's eyes should be in line with a point on the screen about 2-3"
below the top of the monitor. We see more visual field below the horizon
than above this, so at this position the user should comfortably be able
to see more of the screen. If the monitor is too low, the user will crane
their neck forwards, if it's too high they'll tilt their head backwards
and end up with neck/shoulder pain.
- it should be at a comfortable horizontal distance for viewing, which
usually is around an arms length (sit back in your chair and raise your
arm and your fingers should touch the screen). At this distance you should
be able to see the viewing area of the monitor without making head movements.
If text looks too small then either use a larger font or magnify the screen
image in the software rather than sitting closer to the monitor.
- in some instances and for some users, such as those who wear bifocal
corrective glasses, the monitor should be tilted backwards and the height
adjusted for comfortable screen viewing.
- If any adjustments feel uncomfortable then change them until the arrangement
feels more comfortable.
- Posture, posture posture! Good posture is the basis of good
workstation ergonomics. Good posture is the best way to avoid a computer-related
injury. To ensure good user posture:
- Watch the user's posture!
- Make sure that the user can reach the keyboard keys with their wrists
as flat as possible (not bent up or down) and straight (not bent left or
right).
- Make sure that the user's elbow angle (the angle between the inner
surface of the upper arm and the forearm) is at or greater than 90 degrees
to avoid nerve compression at the elbow.
- Make sure that they upper arm and elbow are as close to the body and
as relaxed as possible for mouse use - avoid overreaching. Also make sure
that the wrist is as straight as possible when the mouse is being used.
- Make sure the user sits back in the chair and has good back support.
Also check that the feet can be placed flat on the floor or on a footrest.
- Make sure the head and neck are as straight as possible .
- Make sure the posture feels relaxed for the user.
- Keep it close!
- Make sure that those things the user uses most frequently are placed
closest to the user so that they can be conveniently and comfortably reached.
- Make sure that the user is centered on the alphanumeric keyboard. Most
modern keyboards are asymmetrical in design (the alphanumeric keyboard
is to the left and a numeric keypad to the right). If the outer edges of
the keyboard are used as landmarks for centering the keyboard and monitor,
the users hands will be deviated because the alphanumeric keys will be
to the left of the user's midline. Move the keyboard so that the center
of the alphanumeric keys (the B key, is centered on the mid-line of the
user).
- make sure that the phone is also close to you if you frequently use
it.
- A good workstation ergonomic arrangement will allow any computer
user to work in a neutral, relaxed, ideal
typing posture that will minimize the risk of developing any injury.
- Where will the computer be used? Think about the following environmental
conditions where the computer will be used.:
- Lighting - make sure that the lighting isn't too bright. You
shouldn't see any bright light glare on the computer screen. If you do,
move the screen, lower the light level, use a good quality, glass anti-glare
screen. Also make sure that the computer monitor screen isn't backed to
a bright window or facing a bright window so that there's the screen looks
washed out (use a shade or drapes to control window brightness).
- Ventilation - make sure that you use your computer somewhere
that has adequate fresh-air ventilation and that has adequate heating or
cooling so that you feel comfortable when you're working.
- Noise - noise can cause stress and that tenses your muscles
which can increase injury risks. Try to choose a quiet place for your workstation,
and use low volume music, preferably light classical, to mask the hum of
any fans or other sound sources.
- Take a break! All ergonomists agree that it's a good idea to
take frequent, brief rest breaks: Practice the following:
- Eye breaks - looking at a computer screen for a while causes
some changes in how the eyes work, causes you to blink less often, and
exposes more of the eye surface to the air. Every 15 minutes you should
briefly look away from the screen for a minute or two to a more distant
scene, preferably something more that 20 feet away. This lets the muscles
inside the eye relax. Also, blink your eyes rapidly for a few seconds.
This refreshes the tear film and clears dust form the eye surface.
- Micro-breaks - most typing is done in bursts rather than continuously.
Between these bursts of activity you should rest your hands in a relaxed,
flat, straight posture.
- Rest breaks - every 30 to 60 minutes you should take a brief
rest break. During this break stand up, move around and do something else.
Go and get a drink of water, soda, tea, coffee or whatever. This allows
you to rest and exercise different muscles and you'll feel less tired.
- Exercise breaks - there are many stretching and gentle exercises
that you can do to help relieve muscle fatigue. You should do these every
1-2 hours.
- Ergonomic software - working at a computer can be hypnotic,
and often you don't realize how long you've been working and how much you've
been typing and mousing. You can get excellent ergonomic software that
you can install on your computer. The best software will run in the background
and it will monitor how much you've been using the computer. It will prompt
you to take a rest break at appropriate intervals, and it will suggest
simple exercises.
- What about ergonomic gizmos? These days just about everything
is labeled as being "ergonomically designed" and much of the
time this isn't true and these so-called ergonomic products can make things
worse. If you're thinking about buying an "ergonomic product"
as yourself the following 4 questions:
- Does the product design and the manufacturer's claims make sense?
- What research evidence can the manufacturer provide to support their
claims? Be suspicious of products that haven't been studied by researchers.
- Does it feel comfortable to use the product? If it doesn't then don't
use it!
- What do ergonomics experts say about the product? If they don't recommend
it don't use it.
There are many computer-related "ergonomic" products, the most
common ones being:
- "ergonomic" keyboards - most of these are keyboards
where the alphanumeric keys are split at an angle. For a non-touch typist
this design can be a disaster! The split design only addresses issues of
hand ulnar deviation, and research studies show that vertical hand posture
(wrist extension) is more important. There is no consistent research evidence
that most of the split-keyboard designs currently available really produce
any substantial postural benefits. For most people a regular keyboard design
works just fine if it's put in the proper
position.
- "ergonomic" mouses - many of these mouse designs or
alternative input device designs can work well to improve your hand/wrist
posture. However, it's important to check that you can use these with your
upper arm relaxed and as close to your body as possible. Overreaching to
an "ergonomic mouse" defeats any benefits of this design.
- Wrist rests - these were very popular a few years ago, but research
studies haven't demonstrated any substantial benefits for wrist rests.
If you choose to use a wrist rest a broad, flat surface design works best.
Avoid soft and squishy wrist rests because these will contour to your wrist
and encourage wrist-twisting movements. Your hands should be able to glide
over the surface of a wrist rest during typing.
- Support braces/gloves - There is no consistent research evidence
that wearing wrist supports during computer use actually helps reduce the
risk of injury. If you do like wearing a wrist support make sure that it
keeps your hand flat and straight, not bent upwards. There is some evidence
that wearing wrist supports at night in bed can help relieve symptoms for
those with carpal tunnel syndrome.
The above 10 tips give a brief summary of good ergonomic design practice
for computer workstations, but there's lots more to consider. You can read
about ergonomics in many books, you can browse other materials on this CUErgo web site, you can get information from
the Human Factors and Ergonomics Society, and you can ask expert ergonomists
for help and advice.
If you have any questions or comments about the information on this page
or this web site you can send these to Professor
Alan Hedge at Cornell University.
Happy computing!
Note that all materials on this page and web site are
copyright and may not be copied or distributed without permission.
© Alan Hedge, 2/6/99