Display Screen Equipment Guidance

INTRODUCTION

Display screen equipment (DSE) is defined as 'any alphanumeric or graphic display screen, regardless of the display process involved'. This type of equipment can be found in many areas of industry and commerce, with the most common use being word processing. The regulations covering display screen equipment, not only cover the screens, but all associated equipment, e.g. desk, chair, telephone, printer, modem, software etc. as well as the lighting and general environment around the workstation.

MAIN HAZARDS

Hazards presented by display screen equipment are generally as a result of the way in which it is used rather than the equipment itself, such as incorrect posture, adjustment of equipment or prolonged use.

Postural difficulties often take the form of back and neck ache as well as sprains and strains of areas such as fingers, hands, wrist, elbow and shoulder. Visual fatigue can result in eyestrain, headaches or other related symptoms. All types of fatigue may be as a result of poor ergonomics and working arrangements.

CONTROL MEASURES

The regulations only apply to 'users' or 'operators' of display screen equipment, but any users or operators of this type of equipment not covered by the regulations are still subject to general health and safety legislation. For example, provision of suitable lighting, workstation layout and training.

DEFINITIONS

Display screen equipment - any alphanumeric or graphic display screen, regardless of the display process involved.

Operator - a self employed person who habitually uses display screen equipment as a significant part of their normal work.

Workstation - an assembly comprising of screen, keyboard or other inputting device, printer, modem, desk, chair, etc. plus the immediate work environment around the display screen equipment.

User - an employee who habitually uses display screen equipment as a significant part of their normal work.

CHECKLIST TO IDENTIFY USERS

If most or all of the following points apply then the person is a user.

The individual depends on display screen equipment to do the job, i.e. there is no other readily available way of doing the job.
The individual has no discretion in whether or not to use the equipment.
The individual needs significant training and/or particular skills in the use of display screen equipment to do the job.
The individual normally uses display screen equipment for continuous spells of an hour or more.
The individual uses the equipment more or less daily.
Fast transfer of information between the user and screen is important.
The system requires high levels of attention and concentration by the user e.g. where consequences of error may be critical.

ASSESSMENTS

The regulations require that a risk assessment is carried out to identify any hazards, evaluate the risk, and identify the control measures required.

CONTROL MEASURES

Many hazards can be eliminated if the display screen equipment matches the ergonomic and comfort needs of the user or operator. These control measures include the following.

Lighting

Lighting should be appropriate for all the tasks performed at the workstation, e.g. reading from the screen, keyboard work, reading printed text, writing on paper etc.
General lighting by artificial or natural light should illuminate the entire room to an adequate standard.
Any supplementary lighting provided to cater for personal needs or a particular task should not adversely affect visual conditions at nearby workstations.
Generally, natural lighting is preferable to artificial lighting.

Reflections and glare

Problems that can lead to visual fatigue and stress can arise from unshielded bright lights or bright areas in the worker's field of view as well as from reflections on the screen or other parts of the workstation.
Measures to minimise these problems include:

Note: Anti-glare screen filters should be considered as a last resort if other measures fail to solve the problem.

Work Desk/Surface - Work Station Equipment

Consult the guidance literature supplied by the manufacturers of the particular display screens concerned for guidance about desks and tables. Discuss the requirements with the operators to establish any special circumstances which require consideration.
Consideration should be given to desk top height, thigh clearance as well as knee-hole depth and width. The ideal is for the thighs to be horizontal and for the desk top height to be between 580 - 790mm to comply with current standards.
Table-top printers for standing operations should be installed to a height which provides a normal working position.

Note: Further advice should be sought for ergonomic factors.

For tasks consisting of prolonged and consistent use of a display screen, e.g. data entry, the keyboard height should be such that when the user's fingers are resting comfortably on the home-row keys, the angle of the elbow is 90°. The equipment used should be capable of meeting this requirement.
The keyboard should be able to be tilted and separated from the screen to enable the operator to find a comfortable position, thereby avoiding fatigue in the arms or hands.
The work desk or work surface should be sufficiently large for the operator to have all necessary work aids required. Ideally, it should be a large, low reflection surface and should allow flexible arrangement of the screen, keyboard, documents and related equipment.
Most display screen tasks involve the use of some kind of source documentation or reference material. Where appropriate a document holder should be provided. This should be stable, adjustable and positioned so as to minimise the need for uncomfortable head and eye movements. The holder should be a similar viewing distance from and in the same plane as the display screen.
For displays with vertical screens, the top row of displayed characters should be level with or just below the user's eye height when the user is in a comfortable operating position.
For displays with tilted screens, an imaginary line joining the centre of the screen to the user's eye should be about 15° below the horizontal in the operating position.
Unless otherwise stated in the guidance literature, display screens are usually designed to be viewed from between 350 and 600mm. Desks or tables should be deep enough to accommodate the display screen, thus enabling viewing at these distances without cramping the work surface in front of the display.
When existing furniture is replaced, the new furniture should not deprive the person of existing facilities.

Work Chair

The chair provided should be stable, e.g. the wheels of swivel chairs should have 5 points of floor contact for maximum stability, and be capable of full adjustment to suit the operator, i.e. the chair itself should be adjustable in height, and the seat back adjustable in both height and tilt.
A footrest should be provided, if needed, to ensure that users do not bend their knees back to place feet on the chair, which reduces the blood supply to the lower legs and feet.

Operating Considerations

Eye Tests. On request, eyesight tests should be made available to all users or potential users, free of charge to the employee. At intervals advised by the optometrist or competent person, these should be repeated. The purpose of testing is to identify any eye sight deficiencies in respect of the use of display screen equipment.
Spectacles required for use with display screen equipment should also be provided at the employer's expense.

Note: Any corrective lens required by the individual which is not associated with display screen equipment would be at the individual's own expense.

Where temporary staff are employed, e.g. from an agency, the primary employer of the temporary staff is responsible for the above mentioned eye tests and related costs.

It is recommended that work at display screen equipment is organised in such a way as to ensure natural breaks, e.g. alternating between this and other types of work.

Breaks for non-display screen based work should be arranged so that they are taken prior to the onset of fatigue and not as a recuperative period from it. Short, frequently occurring breaks appear to be more effective than longer ones taken occasionally.

MAINTENANCE

All display screen equipment should be serviced and maintained in accordance with the manufacturer's instructions and in addition, should be covered by the inspection programme for portable electrical equipment.

For advice on the maintenance of equipment such as display screens, personal computers etc. reference should be made to the Guidance on Electrical Safety where recommendations for periodic safety checks for IT equipment are given.

TRAINING

Training should cover the following areas:
the positioning of display screens and equipment, with a view to eliminating glare.
the seating position, its importance and means of adjusting it.
facilities for and importance of eye testing, correct spectacles etc.
the need for regular breaks and facilities for this purpose.

EFFECTS ON PREGNANT WOMEN

Although there has been considerable concern expressed about possible miscarriage and birth defects as a result of exposure to electromagnetic radiation given off by display screen equipment, these concerns have not been confirmed by the many scientific studies carried out. There is, therefore, no need for pregnant women to stop work with display screen equipment. However, as concern can lead to stress and anxiety, they should be treated sympathetically.