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The introduction of VDU’s and other display screen
equipment (DSE) has been associated with a range of symptoms relating to the visual system
and working posture. They can be readily prevented by applying ergonomic principles to
the design, selection and installation of DSE, the design of the workarea and the
organisation of tasks.
This document aims to inform PC users of possible
health risks and gives a minimum requirement for optimal posture. It was originally
written as a guide for post-graduate students within Physics Department
Body Fatigue and Stress.
The most common symptoms and complaints relate to
ergonomic factors i.e. body fatigue caused by poor visual environments, poor working
postures or badly designed work areas. Many symptoms described by display screen workers
reflect stress arising from their task. They may be secondary to upper limb or visual
problems but they are more likely to be caused by poor job design/organisation, lack of
sufficient control over workload, under utilisation of skills, repetitive work or social
isolation
Upper Limb Discomfort and Pains.
A range of conditions of the arm, hand and shoulder
areas linked to work activities are described as Work Related Upper Limb Disorders (WRULD)
or Repetative Strain Injury (RSI).
These range from temporary fatigue to chronic soft tissue disorders.
The cause of these can be a number of combined factors
including prolonged static posture of back and neck, awkward hand positioning, equipment
badly positioned, inadequate lighting and sub-standard equipment.
Eye and Eyesight Effects.
DSE is not associated with damage to the eyes or
eyesight nor does it make existing defects worse. DSE may make workers with existing
visual disorders more aware of them. Some workers may experience temporary visual fatigue
such as impaired visual performance, red or sore eyes and headaches.
These symptoms may be caused by:
- Staying in the same position and concentrating for long
periods-Try to take a break regularly. 15 minutes break for every 90 minutes of work is
advised.
- Poor positioning of DSE-Reposition equipment to achieve
minimal risk to health.
- Poor legibility of screen or source documents-Adjust
screen focus as far as possible.
- Poor lighting, including glare and reflections-Adjust
position of screen to minimise glare from overhead lights and to minimise reflections of
sunlight through windows. Use blinds.
- Drifting, flickering or jittering image on screen
Such uncorrected defects can make work with DSE more
tiring or stressful than it should be.
Other Concerns.
Epilepsy: DSE has not been known to induce epileptic
seizures. People suffering from the very rare photosensitive epilepsy who react adversely
to flickering lights and patterns find they can safely work with display screens.
Facial dermatitis: Some DSE workers have reported
facial skin complaints such as itching or reddened skin. These complaints are rare and
limited evidence suggests they may be associated more with environmental factors such as
low humidity or static electricity near VDU’s.
Electro magnetic radiation: The levels of ionising and
non-ionising electromagnetic radiation which is likely to be generated by DSE are well
below those set out in international recommendations for limiting risk to human health
created by such emissions. The National Radiological Protection Board does not consider
such levels to pose a significant risk to health.
Pregnancy and Miscarriages: Many studies have been
carried out, but taken as a whole their results do not show any links between miscarriages
or birth defects and working with DSE. Pregnant women do not need to stop working with
DSE.
Minimum Requirement of Workstations.
The guidelines below set out the minimum standard for
Display Screen Equipment. Where the assessor decides that a particular workstation is not
being worked at by a display screen USER, there is no legal need for that
workstation to comply with the minimum regulations. In some cases, it may not be
practical to apply these standards. The Physics department tries to conform to the minimum
requirements as far as reasonably practicable.
Display Screens
A satisfactory display screen should be free from
flicker to 90% of users. The image should be clear and stable. There should be a means of
adjusting the brightness and contrast. The display screen should have adjustment
mechanisms to allow the screen to be tilted or swivelled to avoid glare and enable the
worker to maintain a natural and relaxed posture.
Keyboard.
The most important requirement for the keyboard is that
it should have space between the keyboard and the front edge of the desk to provide hand
and wrist support. Further hand comfort is provided if the keyboard has a shallow tilt.
Work surfaces.
Work surface dimensions may need to be larger than for
a conventional desk in order to accommodate back cables, hand support, documents and
writing, as well as the equipment itself. Minimum width=120cm, height from floor=66cm (max
73cm), depth=60cm. To obtain good working posture, there should also be enough room below
the work surface in which to stretch and move legs.
Chair.
The primary requirement here is that the chair should
allow the user to achieve a comfortable position.
Ideally there should be mechanisms to adjust the height
and seat back. Footrest may be provided if users are unable to rest their feet on the
floor. Using a footrest where they are not required may result in bad posture.
Lighting, reflections and glare.
Lighting should be appropriate for all the tasks
performed at the workstation. General lighting should illuminate the room to an adequate
standard. Supplementary lighting may be provided for the individual needs of USERS.
Problems which can lead to visual fatigue can arise from bright light (artificial or
natural), light imbalance and reflections on the screen or on other parts of the
workstation.
Measures to minimise these problems include:
- Re arranging or moving workstations/work surfaces
- Replacing or repositioning sources of light
- Shielding such as window blinds
- Altering display illuminance
Or a combination of the above.
Anti-glare filters should only be considered as a last
resort if other measures fail to solve the problem.
Environment.
Noise from equipment such as printers should be kept at
levels, which do not impair the concentration or prevent normal conversation.
Heat and humidity: Electronic equipment produces dry
heat, which may modify the environment around the workstation. Levels should be maintained
which prevent discomfort and problems of sore eyes.
Work tasks should be designed to give the DSE operator
opportunities of rest from the display. Variety of work will lessen any stresses or
strains. Other tasks such as photocopying, giving advice or doing paperwork give the user
a rest from the display. If there can not be a variety of tasks and the user must work
continually at the display, it is recommended that a few minutes away from the screen
every 35 minutes will aid comfort, even if the user just walks around the room to stretch.
Summary.
The regulations covering Display Screen Equipment do
not just include the monitor sitting in front of a person. They incorporate all the
surrounding peripheral equipment, furniture, lighting and a person’s work tasks, to
name a few factors. The whole workstation area is assessed. Adjustments or even
repositioning of the DSE may be recommended so that the risks to health are minimised as
far as reasonably practicable.
