Support Material - Checklist
Support Material - Checklist
Chairs and posture checklist for keyboard workers
Well adjusted chairs improve body position and blood circulation, reduce muscular effort and decrease pressure on the worker's back. Chairs should swivel, have five wheels for stability, breathable fabric on the seat, a rounded front edge and have adjustable seat height and backrest for lumbar support.
1. Work surface height
Adjust the height of the work surface and/or the chair so that the work surface is approximately at finger length below the height of the elbow when seated.
2. Chair
Adjust the seat tilt so that you are comfortable when using the keyboard. Usually this will be close to horizontal but tilted slightly forwards. If this places an uncomfortable strain on the leg muscles or if the feet do not reach the floor then a footrest should be used. Adjust the backrest so that it supports the lower back when you are sitting upright.
3. Keyboard placement
Place the keyboard in a position that allows the forearms to be close to horizontal and the wrists to be straight. That is, with the hand in line with the forearm. If this causes the elbows to be held far out from the side of the body re-check item 1 .
4. Screen placement
Set the eye to screen distance at the distance that permits you to most easily focus on the screen. Usually this will be within an arm's length. Set the height of the monitor so that the top of the screen is below eye level and the bottom of the screen can be read without a marked inclination of the head. Usually this means that the centre
of the screen will need to be near shoulder height.
5. Desk-top layout
Place all controls and task materials within comfortable reach of both hands so that there is no unnecessary twisting of any part of the body.
6. Document holder
Place this close to the monitor screen in the position that causes the least twisting or inclination of the head.
7. Posture and movement
Change posture at frequent intervals to minimise fatigue. Avoid awkward postures at the extremes of the joint range, especially the wrists. Take frequent short rests rather than infrequent longer rests. Avoid sharp increases in work rate. Changes should be gradual enough to ensure that the workload does not result in excessive fatigue. After prolonged absences from work the overall duration of periods of keyboard work should be increased gradually if conditions permit.Lighting for VDUs
Place VDUs to the side of the light source(s), not directly underneath. Try to site desks between rows of lights. If the lighting is fluorescent strip lighting, the sides of the desks should be parallel with the lights.
Try not to put the screen near a window. If it is unavoidable ensure that neither the screen nor the operator faces the window.
If the VDU is well away from windows, there are no other sources of bright light and prolonged desk-work is the norm, use a low level of . service light of 300 lux. If there are strongly contrasting light levels then a moderate level of lighting of 400 to 500 lux may be desirable but high quality anti-glare screens may be necessary.
Glare and reflection
It is important to detect the presence of glare and reflection. To
determine whether there is glare from overhead lights the seated worker should hold an object such as a book above the eyes at
eyebrow level and establish whether the screen image becomes
clearer in the absence of overhead glare. To detect whether there are reflections from the desk surface the worker should hold the
book above the surface and assess the change in reflected glare from the screen.
A number of ways are available to eliminate or reduce the
influence of these reflections:
=>Tilt the screen so that reflections are directed below eye level.
=> Purchase screens with matt or light diffusing surfaces-over screens with a light diffusing surface or anti-glare screen.
=> Negative contrast screens (dark characters on light background) will reduce the influence of these reflections.
If VDU users experience eye discomfort when using a bright screen they should make the following adjustments:
=> Turn the screen brightness down to a comfortable level. This can be judged by placing a piece of paper next to the screen and adjusting the brightness control so that the screen is similar in brightness to the paper.
=> Look away into the distance in order to rest the eyes for a short while every ten minutes or so.
=> Change the text and background colours. Recommended are black characters on white or yellow background, or yellow on black, white on black, white on blue and green on white. Avoid red and green and yellow on white.Using a mouse
A well designed mouse should not cause undue pressure on the wrist and forearm muscles. A large bulky mouse may keep the wrist continuously bent at an uncomfortable angle. Pressure can be reduced by releasing the mouse at frequent intervals, by selecting a slim-line, low-profile mouse and by using the mouse at a comfortable distance from the body.
Keyboard equipment and radiation
VDUs emit radiation, particularly visible light which allows the characters on the screen to be seen. Weak electromagnetic fields and very low levels of other radiation, not visible to the human eye, can be detected by sensitive instruments. Similar emissions are produced by television receivers. The levels of most radiations and electromagnetic fields emitted from VDUs are much less than those from natural sources, such as the sun or even the human body, and are well below levels considered harmful by responsible expert bodies such as the International Radiation Protection Association. Given that the levels of radiation from VDUs are much lower than recommended limits, and that these limits themselves incorporate significant safety factors, it is extremely unlikely that any harm to an unborn child would result from exposure to the radiation emissions from a VDU .
The weak electromagnetic fields produced by television receivers and VDUs extend in all directions, but their intensity decreases very quickly with distance from the source. A workplace should be organised to ensure that VDU operators are no closer to any other VDUs than they are to their own. Flat screen displays, such as the liquid-crystal display used in some lap-top computers, produce even smaller amounts of radiation than those which use television-type tubes. It may be sensible to use the new types for special purposes, such as to increase portability but concern about radiation emissions should not be a factor in their choice.
Although concerns have been raised that radiation from VDUs is a cause of cancer, research to date has failed to establish a causal link.
Keyboard and telephone operations
Lightweight adjustable headsets with a volume control should be provided for staff on continuous keyboard/telephone operation. For continuous, traffic dependent telephone operations a manual call facility should also be provided.