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Display Screens

Computer systems are now very common in all walks of life. The health risks to users of this equipment are reasonably well known, but consideration must be given to other equipment that is being used alongside the display screen, such as a keyboard, mouse, seat and the rest of the workstation.

Similarly, other kinds of display screens are commonly used from visual displays on point-of-sale machines, CCTV security systems and monitors used on organs for the organist to see the choirmaster. Although regulations don't always apply to these kinds of equipment, the basic principles should always be followed.

The continued and prolonged use of display screens can cause eye strains and neck pains and the use of keyboards and mice can lead to upper limb disorders (including Repetitive Strain Injuries).  These issues must be considered when undertaking a Risk Assessment and discussing the assessment with each user might highlight problems that would otherwise become unnoticed.

Computers

The most commonly encountered piece of display screen equipment is the computer. The design of computer workstation and equipment selection should take into account a number of items to ensure user comfort:

  • The user should be able to make necessary adjustments to ensure comfortable use of the computer
  • The user's arms should be approximately horizontal
  • There might be enough space in front of the keyboard for a person to rest their wrists between keyboard operations
  • Mice should be placed near to the keyboard and on the same level
  • Mice should be used with suitable mouse mats and ball-type mice should be cleaned regularly to prevent dust preventing freedom of movement
  • The cables of keyboard and mice might cause problems if cables get tangled consider using wireless mice and keyboards
  • There might be adequate knee room under the keyboard
  • Wrist rests and screen glare filters are optional and should be provided if there is a request
  • Document holders can be used to keep papers at the same height and viewing distance as the screen
  • A foot rest might be required by the user if their feet do not reach the floor

One key part of the computer workstation is the char.  Any chair used for computer work should be user-adjustable in height, back-rest height and tilt, lumbar support and general comfort. The chair should be soft so that it does not place pressure on the thighs and have a five-legged base for stability.

As the screen is the main way a person views the information from a computer, it should be large enough to be read comfortably (such as a 17" screen) and the settings should enable the smallest of objects to be seen with ease and without distortion. Screens should be positioned so reflections from windows and lights are avoided, and ideally should not be placed pointing a window.

An employee is classified as a display screen "user" if they use the screen for a major part of their work (often anything above 1 hour per working day is usually taken as a guideline figure). If the employee requests, the employer must pay for a eyesight test to be carried out in work time, and the costs of any corrective lenses for display screen work if this is considered necessary by the optician.

People that use or operate computers should receive information and training on how to set up the screen correctly (including tilt, brightness and contrast controls), where to locate the keyboard and mouse and how to arrange other accessories such as foot rests, lighting and the chair. Training would typically cover the risks associated with display screen work, symptoms of common disorders and how to report these.

Any person using computer equipment must be encouraged to take breaks away from the screen.  This might be a planned rest break, or might be time to carry out another task. One recommendation is between 5 and 10 minutes break away from the screen every 50 to 60 minutes, but the person should be able to choose when to take a break for best effect.

A final note is to be made about the tripping hazards of cables. Cables must be run so that they are not a tripping hazard.  An easy way to do this would be to run the cables in bundles, securing them with cable ties so that they are off the floor.  Please see our Slips and Trips page and also our Electrical Safety pages.

Notebook computers

Portable computers (such as laptops and notebooks) are often used as a substitute for a 'normal' computer. One disadvantage of these computers is the fixed position of the keyboard, mouse and screen and the limited adjustment of the screen tilt.  A 'normal' mouse can be used for comfort but other elements of the computer design cannot be altered and might cause a person using the equipment some discomfort.

Extensive use of these computers is not recommended where there is a standard computer available or where the portability or compact size is not required.  There is a tendency to use notebook and laptop computers in ways that could increase the chance of injury (such as on the lap or on soft furnishings) and these methods should be avoided. The screen should be tilted and positioned to give the best viewing usually the screen needs to be directly in front of the person and tilted slightly upwards.

Tablets and Mobile Devices

Recent developments in portable computer devices have created ever smaller screen sizes and devices. Tablet PCs and mobile devices can now come with a wide range of software 'apps' that can achieve many wide and varied tasks which make them all the more useful.

There are two significant issues to be considered:

  1. The display size.  This is often small in size, due to the nature of the device being portable.  This is more of an issue for mobile phones due to the very small screen size. In either case, a smaller screen can result in the onset of eyestrain more rapidly than, say, a laptop computer.
  2. The on-screen keyboard and touch-screen. For short-term use, a touch-screen is adequate but are not suitable for long-term use. Overuse of the thumbs while keying in information is becoming an increasing problem because the on-screen keyboard does not lend itself to ergonomic typing.

Although small 'bluetooth' keyboards and mice may be bought which may alleviate some of the issues listed above, the small screen makes this kind of equipment only useful for short duration work.

Projector systems

Projector systems are becoming increasingly used in Churches and Places of Worship as a means to display hymn and song words, readings and presentations.  These systems needs to be designed with care to maximise usability usefulness while preventing eye-strains and other problems that could occur.

The screen itself should be positioned at a height that provide easy and unrestricted viewing, but not too high so people have to bend their head upwards to see the screen (especially when seated near the front). In some cases, more than one screen might be required, especially if there are obstructions such as pillars. 

Screens can be of different sizes and types depending on where they are placed and who is viewing the screen.  Splitters are available to enable more than one monitor or projector to be fed from one computer output.

Projectors should be chosen to ensure the brightness of the screen will be adequate, especially if there are other sources of bright lighting, or daylight, present.  Text displayed should be of a clear typeface, be large enough to comfortably read and a colour contrast between the displayed text and the background should always be maintained. Although it is popular, the use of images behind song words can reduce the readability of the screen, and can result in eyestrain.

Additional Information

Guidance on the Health and Safety (Display Screen Equipment) Regulations is available from the Health and Safety Executive.  "Work with display screen equipment" (L26), ISBN 0717625826.

Guidance for users of display screens is available from the free HSE leaflet "Working with VDUs" (INDG36).

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