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9 Workplace ergonomics and the DSE Schedule

The Display Screen Equipment (DSE) Regulations contain a Schedule (which is what is in the original European Directive) and an Annex (which is the UK interpretation thereof) which give guidance on the minimum requirements for workstations. These apply to the normal office use of VDUs but may not apply to some specialist uses where other health and safety factors intervene.

There are a number of examples cited later where the Annex has sought to interpret the Schedule in a manner which would result in minimum change and minimum expense to employers. There are certainly a number of ambiguities which will ultimately be settled in the courts. However, there are two features built into the Regulations which are particularly helpful to workers and trade unions trying to ensure that safe conditions are created. One is that the suggestions and opinions of VDU users should be incorporated into the assessment. The other is that representatives of recognised unions should be involved in carrying out the assessment. It is therefore worthwhile being acquainted with the scope for argument which the regulations permit.

Ergonomic standards

The Annex advises that ergonomic standards for VDUs are contained in British Standard BS 7179, a six-part interim standard concerned with efficient use of equipment as well as health and safety. International standards are in preparation and will in due course supersede BS 7179. This will be withdrawn when the European standards organisation Comité Européen de Normalisation (CEN) issues its own multipart standard (EN 29241) on the ergonomics of design and use of VDUs in offices. This standard will in turn be based on an ISO standard (ISO 9241) currently being developed. While the CEN standard is not formally linked to the Regulations, one of its aims is to establish levels of protection for users. The Annex makes clear that while employers may find the standards helpful in meeting their obligations, they are not obliged to comply with them.

BS 3044 is a general guide to ergonomic principles in the design and selection of office furniture; it will also be superseded by a CEN standard in due course. More detailed and stringent standards apply to specialised applications of VDUs, such as process control, applications with machinery safety implications and safety of programmable electronic systems. Details of standards are available from the Department of Trade and Industry (see Contacts and resources).

The factors dealt with in the Annex and Schedule are the display screen, the keyboard, document holder, desk, chair, footrest, space, lighting, reflections and glare, noise, heat, radiation, humidity, software and job design. In the following paragraphs, the requirements of the Schedule are mentioned first, followed by the interpretation mentioned in the Annex, with commentary where this is appropriate.

Screens

The choice of screen should be based on environmental factors and on the type and amount of information required to be displayed. This may require a customised screen to be provided or a standard model to be adapted. The characters should be well defined and clearly formed, of adequate size and with adequate spacing between the characters and lines.

The image on the screen should be stable, with no flickering or other forms of instability. This is interpreted in the Annex to mean that the screen should be flicker free for 90 percent of users, which is exposing 10 per cent of users (perhaps a million people) to visual fatigue. The brightness and contrast between the characters and the background should be easily adjustable, taking into account ambient conditions. Light characters on a dark background or dark characters on a light background are both acceptable, the choice being determined by the overall conditions. With light characters flicker is less perceptible and characters seem bigger; with dark characters reflections are less perceptible and edges appear sharper. There is no recommendation on the colours of characters and background, which has receded as a health and safety issue.

The screen should swivel and tilt easily and freely to suit the needs of the worker. However, this point is a good example of the efforts to water down the Directive when translating it into UK law. The Schedule, the European bit, reads, "It shall be possible to use a separate base for the screen or an adjustable table." The Annex, the UK interpretation of the Schedule, reads, "The reference in the Schedule to adjustable tables does not mean that these have to be provided." It may be surmised that this is more on grounds of expense to employers than on safety. The screen should be free of glare and reflections (for more on this see later).

Document holders

Document holders are optional but can be useful for workers with difficulty in refocusing. They should position documents at a height, visual plane and viewing distance similar to those of the screen. They should be adjustable in all three planes. They should be of low reflectance, stable and not reduce the readability of source documents.

Keyboards

Keyboards should be detachable from the monitor and should also be tiltable. Keys should be easily legible. The keyboard should be of low reflectance. The Annex refers to hand support being incorporated into the keyboard or attached in some form to the work surface. It is not at all clear that such devices contribute to safety at all and may even detract from it. The Annex also refers to a space between the keyboard and the front edge of the desk where the hands or wrist can rest, and this should be available though it is a matter of the individual worker's preference whether such a space should be used.

Non-keyboard accessories

No mention is made of mice, trackballs, joysticks or other non-keyboard devices, an omission possibly related to the lengthy gestation period of European legislation, and therefore the health and safety implications of such devices needs to be dealt with under the Management of Health and Safety at Work or the Provision and Use of Work Equipment Regulations.

Work desks

The work desk or surface should have a sufficiently large, low-reflectance surface to allow a flexible arrangement of all the VDU and other equipment. The dimensions may need to be larger than for non-screen work to allow for the range of tasks performed, the position required to perform them, and the space needed to use and store working materials and equipment. The worker must have enough space to find a comfortable position and adequate clearance for postural changes. The desk should therefore be at a suitable height to enable this to happen (see above on the adjustability of desks).

Footrests

A footrest should be made available to any worker who wants one, ie. the worker has to ask for one, it will not arrive automatically. The Annex comments that footrests may be necessary where work surfaces cannot be adjusted to the right height in relation to the rest of the workstation. There is a large element of individual preference in their use.

Chairs

Chairs should be stable and allow the worker freedom of movement and comfort. The seat should be adjustable in height. The seat back should be adjustable in both height and tilt. According to the Annex, provided the seat height is adjustable relative to the ground and the seat back is adjustable in height relative to the ground and tilt, it is not necessary for the seat and the seat back to be independently adjustable from each other. Again this is a get-out for employers unwilling to invest in good quality equipment but is the antithesis of ergonomics principles which say design the tools to fit the worker not design the worker to fit the tools.

Lighting

Room or task lighting should ensure satisfactory lighting conditions and an appropriate contrast between the screen and the background environment, taking into account the type of work and the vision requirements of the worker. The Annex comments that general lighting should illuminate the entire room to an adequate standard and supplementary individual lighting should not adversely affect nearby workstations. High illuminance renders screen characters less easy to see but improves the readability of documents. In this case screens with dark characters on a light background have the advantage over light characters on a dark background. Neither the Schedule nor the Annex express a preference for natural over artificial lighting. It appears that the employer is obliged to provide adequate general lighting but supplementary individual lighting is discretionary (and therefore open to bargaining).

Glare and reflections on the screen or other equipment should be prevented by co-ordinating workplace and workstation layout with the positioning and technical characteristics of the artificial light sources. Sources of light, such as windows, transparent walls, or brightly coloured surfaces, should cause no direct glare and no distracting reflections on the screen. Windows should be fitted with an adjustable covering to attenuate daylight.

The Annex comments that visual fatigue and stress can arise from unshielded bright lights, from an imbalance between brightly and dimly lit areas, and reflections on the screen or other parts of the workstation. Measures to minimise these problems include: shielding, replacing or repositioning sources of light; rearranging or moving work surfaces, documents or all or parts of workstations; modifying the colour or reflectance of walls, ceilings, furnishings, etc. near the workstation; altering the intensity of vertical to horizontal illuminance; or a combination of these. There is thus enormous scope for bargaining on workstation design in order to get the lighting conditions right. The Annex goes on to comment that anti-glare filters should only be used as a method of last resort. Further guidance on lighting standards is provided by the Health and Safety Executive (HSE 1987) and the Chartered Institute of Building Service Engineers (CIBSE 1989).

Noise

The Schedule has a peculiar formulation on noise - noise emitted by equipment belonging to any workstation shall be taken into account when a workstation is being equipped, with a view in particular to ensuring that attention is not distracted and speech is not disturbed. No-one could deny that guidance is needed on the meaning of that one and the Annex makes a stab at it, advising that noise, basically from printers, can be reduced by replacement, sound-proofing or repositioning of equipment; sound insulating partitions between noisy equipment and the rest of the workstation are an alternative. Noises intended to attract attention, eg. to signal a malfunction, are permitted.

Temperature and humidity

Equipment belonging to a workstation should not produce excess heat and an adequate level of humidity shall be developed and maintained. The Annex does not expand on this and no definitions of appropriate levels are offered on heat and humidity, although it is known that at 50 per cent humidity, most electrostatic fields from VDUs are eliminated (see also Chapter 7).

Radiation

All radiation with the exception of the visible region of the electromagnetic spectrum should be reduced to negligible levels. The Annex is at pains to argue that no special action is necessary to meet this requirement. It is claimed that workers will receive much smaller doses from modern equipment than the maximum exposures recommended by the authorities. For detailed discussion of the limitations of this approach, see Chapter 7.

In addition, there will continue to be large numbers of people using ageing equipment for years to come. The levels are similar to those of domestic appliances, but then not many people sit on their kettles for hours at a stretch. It is claimed that no adverse effects have been shown to result from emissions from VDUs and therefore it is not necessary to take action to reduce levels or even take measurements. There is no need for anti-radiation screens. This is one of the poorest areas of the Regulations where the traditional position of the British authorities on radiation exposure is asserted and the European position given short shrift. The undermining of pregnant workers is obvious.

Fumes and static electricity

Two areas which neither the Schedule or the Annex touch upon are fumes from equipment or static electricity. Thus there is no legal barrier to placing laser printers on workstations thus exposing workers to ozone and other emissions from the printer. There are no recommendations on anti-static mats, preferred carpet materials and other methods of dealing with static. The legal argument will have to be taken up other under legislation in these two areas. Both the Management of Health and Safety and Provision and use of Work Equipment Regulations can be applied to deal with these two problems.

Job design

One area where the Annex definitely scores over the Schedule is job design. The Schedule asserts that inappropriate task design can be a source of stress at work. Stress can jeopardise motivation, effectiveness and efficiency and can lead on to serious health problems. There is a suggestion that productivity and health and safety concerns can come together from the employer's point of view. It is argued that good job design is as important as ergonomics.

Jobs should be designed to offer variety, opportunities to exercise discretion, for learning and for feedback. Staffing levels should be matched to work loads. Users should participate in the planning, design and implementation of work tasks whenever possible. All this, in conjunction with other legislation, allows workers and representatives to argue for a certain amount of control over the job. There will need to be care, though, in distinguishing work methods aimed at increasing productivity from protection of health and safety.

Software

The Schedule introduces an area which previously has not had much attention on health and safety grounds in the UK, that is, software ergonomics. In designing, selecting, commissioning and modifying software, and in designing tasks using VDUs, the employer should take into account:

that the software is suitable for the task that it should be easy to use and adaptable to the knowledge or experience of the worker (monitoring devices cannot be used without the knowledge of the workers) that systems must provide feedback on performance that systems must display information in a format and at a pace adapted to workers that the principles of software ergonomics must be applied to human data processing.

It should be noted that the worker's consent to monitoring is not required, only that s/he should know about it. The Annex does state that badly designed software can affect the health of workers and advocates the involvement of workers in the purchase or design of software. Software should enable workers to adapt the user interface to suit their ability and preferences. Software should also protect workers against the consequences of errors by providing warnings and information and allowing 'lost' data to be retrieved. Feedback should include error messages, help on request and messages on malfunctions and overloading. Feedback messages should be presented at the right time and in an appropriate time and format and should not contain unnecessary information. The speed of response to commands should be appropriate to the task and the worker's abilities. Characters, cursor movements and position changes should where possible be shown on the screen as soon as they are input.

The Annex says that monitoring facilities can lead to stress if there is an over-emphasis on speed and it is possible to design systems that provide information helpful to workers as well as managers. This is a really shameful cop-out and there is no effective legal protection against the range of methods aimed at jacking up productivity at the expense of health and safety.

Overall, the Schedule and the Annex are a hotchpotch. Some parts provide real scope for workers to argue for high quality equipment and conditions; others give the impression of being drawn up with the intention of preventing that happening. There is not a lot there that absolutely requires employers to change what they do now, good or bad. It would thus be a totally false idea to believe that the DSE Regulations will automatically lead to improved standards. Those opportunities they do present have to be taken by vigorous action and good organisation by workers and unions.

Making best use of the regulations

It is vital to get involved in the assessments and negotiate the conditions when new equipment is being introduced. An essential feature of assessments is the opinions of the workers who use the VDUs. One of the best ways to carry out an assessment is to use a checklist which can be completed by the worker or by discussion with the worker. An example of such a checklist is given on page 00. This covers not only the minimum requirements of the Regulations but also other features needed to create a safe workplace. This checklist or something like it can be used by safety representatives to raise the issue of VDU safety in the workplace and put pressure on the employer to make improvements. In the vast majority of cases, only demands from the workforce will induce employers to spend the necessary resources.

VDU workstation inspection checklist

(Based on the Schedule and Technical Annex of the DSE Regulations)

Is the monitor tiltable in all directions? Is it at a suitable height? Are characters well defined, of adequate size, with adequate spacing? Is there any flicker? Are brightness and contrast adjustable? Is the screen free of glare and reflection? Is it easily cleaned?

Is the document holder at a suitable height and position relative to the screen? Is it adjustable in all directions? Does it affect the readability of documents?

Is the keyboard detachable? Is it adjustable? Are the keys easily legible? Has it a matt surface? Is there sufficient space between the keyboard and the edge of the desk? Is there hand or wrist support?

Is a mouse in use? Is it comfortable to grip? Is it possible to click the keys without strain? Is it used on a suitable surface, e.g. a mat? Is a joystick in use? Is it comfortable to grip? Is it easy to move from side to side? Is a trackball in use? Does it fit comfortably into the palm?

Does it allow for the adjustment of other equipment? Is it at a suitable height? Is the height adjustable? Is there sufficient leg room? Are there any obstacles under the desk? Has it a matt surface?

Is the height of the seat adjustable? Is there a back support? Is the back support adjustable in height and tilt? Is the base stable? Is there suitable support for the lumbar region? Is there any pressure on the thighs or the backs of the knees?

Is a footrest available?

Is the workstation cramped? Can the operator change position and vary movements?

Is the workstation suitably positioned relative to natural light sources? Is the workstation suitably positioned relative to artificial light sources?

Is there adequate natural lighting? Are windows fitted with blinds or other protective covering? Do reflection and glare arise from natural lighting? Is there adequate artificial lighting? Do reflection and glare arise from artificial lighting? Are the illuminance and intensity of artificial lighting subject to operator control? Has a desk light been provided? Has an uplighter been provided? Is there an anti-glare screen?

Are all plugs, sockets and switches in a good state of repair? Are any sockets overloaded? Is there any exposed wiring? Are there any trailing wires?

Is the temperature comfortable? Is the level of humidity comfortable? Is there noise from adjacent equipment? Is there street noise? Are there fumes from adjacent equipment? Has an anti-static device been provided? Is there excess radiation from the operator's workstation? Is there excess radiation from adjacent workstations?

Is software suitable for the task? Is software easy to use? Is information displayed in a suitable format? Is information displayed at a suitable speed? Is there feedback on performance? Is any monitoring function in operation? Has appropriate training been provided to the operator?