CUergo: Computer Workstation Ergonomics Guidelines

CUergo: Computer Workstation Ergonomics Guidelines Cornell University Ergonomics Web Ergonomic

CUergo: Computer Workstation Ergonomics Guidelines




Cornell University Ergonomics Web


Ergonomic Guidelines for arranging a Computer
Workstation
10 steps for users


Creating a good ergonomic working arrangement is important to protecting
your health. The following 10 steps are a brief summary of those things that
most Ergonomists agree are important. If you follow the 10 steps they should
help you to improve your working arrangement. You can also use the Computer
Workstation Checklist
to help to pinpoint any areas of concern and take a
look at the ‘Computer Workstation summary’
diagram
‘ for specific tips. 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. Also see my book – Ergonomic Workplace Design for Health, Wellness, and Productivity.


 10 steps 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:


  1. How will the computer be used?  
    • who will be using the computer?  – If the computer will only be
      used by 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 going to be used by 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, as well as those in between these extremes. 
    • 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 it is advisable that you create an ergonomic arrangement. If it’s more than
      4 hours then you should immediately implement an ergonomic arrangement.
  2. What kind of computer will be used?  
    • Desktops – most ergonomic guidelines for
      computer workstation arrangements assume that you will be using a desktop
      system
      where the computer screen is separate from the keyboard. 
    • Laptop
      computers

      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:


    and then arranging your workspace to create a good workstation layout. See
    “5 tips for using a Laptop Computer”.

  3. 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 down 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 and with your wrist in a comfortable and neutral
    position. 

    Thinking about a sit-stand
    workstation
    , see below.

    Thinking about a height-adjustable
    split workstation
    , see below.


  4. 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 even be at a
    fixed height providing that it is comfortable to sit on and has a good
    backrest that provides lumbar support. If more than one person will be using the computer, consider
    buying and a chair with several ergonomic features.
    Studies show that the best seated posture is a reclined posture of 100-110
    degrees NOT the upright 90 degree posture that is often portrayed. In 
    the recommended posture the chair starts to work for the body and there are
    significant decreases in postural muscle activity and in intervertebral disc
    pressure in the lumbar spine. Erect sitting is NOT relaxed, sustainable
    sitting, reclined sitting is.

    Chair armrests – Having armrests on a chair can be helpful to aid
    getting into and getting out of the chair. Also, the armrests can be useful
    for the occasional resting of the arms (e.g. when on the phone, sitting back
    relaxing). However, it is not a good idea to permanently wrest the forearms
    on armrests while you are typing or mousing because this can compress the
    flexor muscles and some armrest can also compress the ulnar never at the
    elbow. Ideally, it should be easy to get the armrests out of the way when
    you need to have free access to the keyboard and mouse. These days most
    office chairs have armrests and many of them have adjustable height
    armrests, so look for a chair that is a comfortable fit to you and that has
    broader, flatter, padded armrests that you can easily move out of the way if
    needed is the best approach. If you are able to occasionally rest your hands
    on the keyboard on a palm rest and if you have a comfortable chair that does
    not have any armrests then this is also quite acceptable.

  5. 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.
  6. 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 you and facing you, not angled to the
      left or right. This helps to eliminate 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 of the screen.
    • center the monitor 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 you 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.
    • put the monitor at a comfortable height that doesn’t make the user tilt their
      head up to see it or bend their neck down to see it. When you are 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 casing (not the screen). Sit back in your chair
      at an angle of around 100-110 degrees (i.e. slight recline) and hold your
      right arm out horizontally, your middle finger should almost touch the
      center of the screen. From that starting position you can then make minor
      changes to screen height and angle to suit. Research shows the center of the
      monitor should be about 17-18 degrees below horizontal for optimal viewing,
      and this is where it will be if you follow the simple arm extension/finger
      pointing tip. You actually see more visual field below the horizon
      than above this (look down a corridor and you’ll see more of the floor than
      the ceiling), so at this position the user should comfortably be able
      to see more of the screen. If the monitor is too low, you will crane
      their neck forwards, if it’s too high you’ll tilt their head backwards
      and end up with neck/shoulder pain. 
    • bifocals and progressive lens – even if you wear bifocals or
      progressive lens, if you sit back in your chair in a reclined posture
      (with you back at around 110 degrees) that is recommended for good low
      back health, rather than sitting erect at 90 degrees, and if you slightly tilt the monitor backwards
      and place this at a comfortable height you should be able to see the screen without
      tilting your head back or craning your neck forwards. Postural problems with bifocals can occur if you sits erect or
      even hunched forwards. The problem with low monitors is that they cause
      neck flexion and suffer more from glare. Recent studies have shown that
      the best position for a computer monitor is for the center of the screen
      to be at around 17.5 degrees below eye level. Try to align your eyes with
      the top of the viewing area of the screen, and this should put the center
      about right geometrically.
    • viewing distance – the monitor 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.
    • screen quality – use a good quality computer screen. Make sure
      that the text characters on your screen look sharp, and that they are a
      comfortable size (you can change the screen resolution to find a
      comfortable and clear character size). If you can see the screen
      flickering out of the corner of your eye you should try increasing the
      refresh rate of your monitor (with a PC you can change monitor resolution
      and refresh rates using the Monitor control panel in your Settings folder,
      with a Mac you can use the Monitor control panel). You can also consider
      using a good quality glass anti-glare filter or an LCD display (like a
      laptop screen).
    • eye checkup – there are natural changes in vision that occur in
      most people during their early 40’s. It’s a good idea to periodically have
      your eyes checked by a qualified professional.
    • If any screen adjustments feel uncomfortable then change them until the arrangement
      feels more comfortable or seek further professional help.
    • Use a
      document holder
      that can be comfortably seen:

      • use an in-line document holder that sits between the
        keyboard/keyboard tray and screen and is aligned with your body midline so
        that all you have to do is look down to see the documents and raise your
        eyes to see the screen.
      • use a  screen-mounted document holder and position this to
        the side of your screen that is your dominant eye
      • use a  freestanding document holder and position this next
        to the side of the screen and slightly angle it so that it follows a curve
        from the side of the screen.

  7. 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 the 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. An
    ideal keyboard arrangement is to place this on a height adjustable
    negative-tilt tray. An ideal mouse arrangement is for this to be on a flat
    surface that’s 1-2″ above the keyboard and moveable over the numeric
    keypad. If you want a surface at the level of the keyboard base then make
    sure that this can also be angled downwards slightly to help to keep your
    hands in wrist neutral while you are mousing, and keep your elbow is as
    close to the body as possible while you work. Check
    out the 10 tips for using a computer mouse.
  • 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 from 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. During a micro-break (< 2minutes) you can briefly
          stretch, stand up, move around, or do a different work task e.g. make a
          phone call). A micro-break isn’t necessarily a break from work, but it’s a
          break from the use of a particular set of muscles that’s doing most of the
          work (e.g. the finger flexors if you’re doing a lot of typing).
        • 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:

    The above 10 steps 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. You can
    use the Computer Workstation Checklist to help
    to identify problems, and you can ask expert
    Ergonomists

    for help and advice.


    Also, see the ‘Computer
    Workstation summary’
    diagram
    created by the DEA651 class of 2000.


    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.


    For more detailed information and exercises you can also check out the free ‘HealthyComputing.com’
    web site.


    Happy computing!



    This guide is translated into
    Serbo-Croatian by Jovana Milutinovich from Geeks Education.
    This guide is translated into
    Polish by Andrey Fomin.
    This guide is translated into
    Russian by
    Oleg Segal
    This guide is translated into
    French by

    Anna Chekovsky


    This guide is translated into
    Ukranian by Ivanka Skakun

    This guide is translated into Kazakh by John Vorohovsky

    This guide is translated into Georgian by Irakli Nishnianidze

     

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    Note that all materials on this page and web site are
    copyright and may only be copied or distributed for nonprofit educational
    purposes without permission.
    © Alan Hedge, page content last revised on
    June 13, 2015


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