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Ergonomics Of Computer Usage


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Presented at seminar in September 2007 in Seychelles medical college. Published here as a 'How-to' for general public information.

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Ergonomics Of Computer Usage

  1. 1. Ergonomics of Computer Usage Dr Sanjoy Sanyal MBBS, MS, MSc (UK), ADPHA, ADHRD Seychelles Presented in Seychelles medical college in September 2007
  2. 2. A few simple measures can avoid a lot of pain in the neck (pun unintended!)
  3. 3. Posturing body parts <ul><li>Computer directly in front </li></ul><ul><li>Forearms horizontal </li></ul><ul><li>Wrists in neutral, comfortable position </li></ul><ul><li>Upper arms hang naturally at sides </li></ul><ul><li>Breaks during sessions </li></ul>
  4. 5. Upper limbs <ul><li>Wrists in neutral position, neither bent up, down nor sideways. </li></ul><ul><li>Do not lean wrists on wrist-straps while typing. </li></ul><ul><li>Shoulders / arms relaxed and hanging naturally. </li></ul><ul><li>Elbow / forearm rest comfortably on work surface, parallel to floor; </li></ul><ul><li>Elbow at 90-degree angle. </li></ul>
  5. 9. Lower limbs <ul><li>Back of knees extending no more than 3-4 finger lengths from end of chair. </li></ul><ul><li>Thighs parallel to floor, comfortably supported on seat of chair </li></ul><ul><li>Leg-torso angle = 90-100 degrees </li></ul><ul><li>Feet in front of seat and resting flat on floor. </li></ul><ul><li>If feet are not reaching floor, adjust height of chair, or put a footrest under feet. </li></ul>
  6. 10. Wrong workstation posture
  7. 11. Correct workstation posture
  8. 12. Spine and back <ul><li>Back in full contact with backrest </li></ul><ul><li>Lumbar curve of chair fitting lumbar spine </li></ul><ul><li>Avoid improper body alignment </li></ul><ul><li>Neck straight or slightly forward. </li></ul><ul><li>Avoid looking up and improper neck posture </li></ul>
  9. 14. Chair <ul><li>Adjustable backrest - tilts easily, yet provides solid back support </li></ul><ul><li>Curved lumbar support </li></ul><ul><li>Able to be raised / lowered, swiveled / locked at different angles </li></ul><ul><li>Average adult : Seat 1½ feet (45 cm) above ground, placed 1½ feet (45 cm) from table; table 2 -2 ½ feet (60-75 cm) high. </li></ul>
  10. 16. Eyes <ul><li>Avoid locking eyes into fixed-screen stare . </li></ul><ul><li>‘ Rule of 30 ’: Every 30 minutes look towards an object approximately 30 feet away, for 30 seconds. </li></ul><ul><li>Keep eyes level with upper margin of monitor </li></ul><ul><li>Should not be necessary to swivel eyes downwards > 40 degrees from horizontal when looking from top to bottom of screen. </li></ul>
  11. 17. Workstation setup
  12. 18. Workstation setup
  13. 19. Workstation setup
  14. 20. Desktop screen <ul><li>Anti-glare screen. </li></ul><ul><li>In front of a window, its back facing the window. </li></ul><ul><li>Screens < 17 inches (43 cm) should be one-arm + 3 inches away from fingertips. </li></ul><ul><li>Larger screens 7-8 inches away from fingertips. </li></ul><ul><li>Or , 1 ½ to 2 feet (45 to 60 cm) from eyes. </li></ul><ul><li>Screen directly in front of user’s eyes, not angled in vertical or horizontal axes. </li></ul>
  15. 21. Laptop screen <ul><li>Adjust viewing angle for: </li></ul><ul><ul><li>Best display </li></ul></ul><ul><ul><li>Least eye strain </li></ul></ul><ul><ul><li>Least muscle fatigue </li></ul></ul><ul><ul><li>Optimum brightness </li></ul></ul>
  16. 22. Desktop peripherals <ul><li>Top margin of monitor at eye-level. </li></ul><ul><li>Mouse to right or left of keyboard, at same height. </li></ul><ul><li>Keyboard located at elbow height </li></ul><ul><li>‘ B'-key lined up with the navel </li></ul><ul><li>Keyboard legs should be knocked down, so that it lies flat on table </li></ul><ul><li>Wrist-rests may be used to reduce strain on wrists. </li></ul>
  17. 23. Room lighting <ul><li>Work area adequately lit / ventilated. </li></ul><ul><li>Windows/lights should not create glare / reflection on display </li></ul><ul><li>Indirect light to avoid bright spots on display </li></ul><ul><ul><li>Overhead lighting is best, or </li></ul></ul><ul><ul><li>Fluorescent light with a grid or shield covering the fixture </li></ul></ul>
  18. 25. “ Keep head on your shoulders, Watch your hand, Look straight, Keep an eye on your back.”
  19. 26. References <ul><li>Dr Venkata Ramana Rao , RSI specialist, myotherapist and ergonomist; RSI Healthcare. </li></ul><ul><li>Rich Epstein , Director of the Moore Center for Rehabilitation, Stamford and a founder of the Moore Center Ergonomics and Injury Prevention Company </li></ul>
  20. 27. THAN-Q