Screen Based Equipment and Safe Use Guidelines
No: PMDG
Approved by: Chair, UHSG Date Approved: 4 September 2006 Administered by: Manager, Health Safety and Environment Next Review: 4 September 2008 Version: 1.0
Purpose
The purpose of this document is to highlight strategies to reduce the incidence of injury/illness to staff through the use of screen-based equipment.
General Information Overview
Briefly, reduction of injury can be obtained by addressing the following: Ergonomic issues in the workplace; The work schedule; Access to effective training and education for use of SBE in the workplace; Environment factors such as lighting, noise; and Providing appropriate equipment and furniture in compliance with AS 3590 (Parts 1, 2 and 3) – 1990. The use of Screen-Based Equipment (SBE) at the University has led to a high incidence of injuries/illness, particularly in association with vision and musculoskeletal conditions. Musculoskeletal conditions are complex and are commonly referred to, although not always correctly, as Cumulative Trauma Disorders (CTD) and Occupational Overuse Syndrome (OOS), formerly known as Repetitive Strain Injury (RSI). Common musculoskeletal disorders include carpal tunnel syndrome, tendonitis, tenosynovitis, and epicondylitis. Vision complaints are mainly eye strain, headaches and blurred vision. Staff of course may have a predisposition to these injuries/conditions. For example the loss of eye focusing that invariably accompanies advancing age (presbyopia) may be the cause of eyestrain and headaches at the workplace and result in the need for prescription lenses, including bifocals and trifocals. Previous musculoskeletal injuries or degenerative medical conditions may be aggravated by the design of the workstation and workplace or operating procedures. The University has a high percentage of staff who have access to and are required to use screen-based equipment. The cost of these injuries in terms of physical suffering to employees and financial liability for the University, particularly those relating to OOS, is high and rivals that of stress claims.
References
Australian Standards: AS 1680 Interior Lighting (Parts 1, 2 and 3) AS 3590/2-1990 Screen based workstations; Part 2 Workstation Furniture AS 3590.3-1990 Screen based workstations Part 3 Input Devices
Setting up your workplace
In setting up the workplace for new employees or simply checking the setup for existing employees the following points should be observed: Adjust the brightness and contract controls of your screen for easy viewing. The display should be clear and bright, without flicker or distortion. Make sure there is no glare or reflection on the screen. Adjust the screen so its top is level with your eyes.
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No: PMDG: Adjust your desk to accommodate you. Your hands and lower arms should be parallel to the desk. Match your elbow heights to the ASDIC row keys. Use a wrist rest if the keyboard is over 4cm high at the front edge. Allow approximately 5cm resting space between keyboard and edge of desk. Make sure your chair is fully and easily adjustable (seat height, backrest height, backrest angle) from a seated position. It should be stable and comfortable with good lower back support. Preferably the source document should be at the same distance, and approximate viewing angle of the screen to minimize head and neck movement. The optimum placement of the document holder will depend on the primary viewed object. Positioning of source documents on holder can be next to and level with the screen; between the VDU and keyboard or directly in front of the user.
Mouse design and operation
The use of a mouse is an integral function to most SBE users. Sustained operation of the mouse can however result in excessive static muscle use. For optimal control and avoidance of symptomatology when using a mouse, one should: Accommodate a close to neutral hand posture with less than ten degrees wrist extension. Allow wrist to rest on work surface (or wrist support). Permit upper limb to adopt a relaxed position so that upper arm is nearly vertical and the lower arm nearly horizontal to the floor. Allow fingers to rest on push buttons without danger of accidental operation. Comply with Australian Standard AS 3590/3-1990 Input Devices as closely as possible for dimensions. Have an anti-static mouse pad.
Good keyboarding techniques
Touch the keys softly. Do not bend your hands up or down at the wrist, or rest your wrists on the edge of the desk. Use all fingers. Keep your hands and fingers relaxed. When you are not keying, rest your hands and wrists. Work with your shoulders relaxed (not hunched up) and your elbows in. Sit upright and well back in your chair, with the backrest supporting the small of your back. Pace yourself and your work. Where possible, avoid bursts of rapid keying. Plan your work. Avoid tension-inducing deadlines. If you have been away from the workplace for an extended period of time, eg holiday, etc, gradually work into the keyboarding routine. Take brief, frequent breaks, to avoid fatigue or discomfort. Task variation is vital to maintain optimum health at work. Regular exercise is essential for keyboard operators to avoid musculoskeletal injuries. Exercises have been specifically developed to maintain flexibility – see the HSE office for advice
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Visual requirements
Good lighting is essential. If you use computers regularly it is advisable to have an annual eye check. Position VDU in optimum location to avoid glare and reflections – away from, and at right angles to the window, with overhead lights to the side and in line with the screen. Control glare at the source, for example, blinds, tinted windows. Optimum eye comfort is influenced by many factors. It may include adjusting the angle of the screen changing the viewing distance, altering the lighting in the work area and by adjusting the screen brightness controls as necessary. Anti-glare screens are also available and these are placed over the computer screen to reduce reflection, glare and eye strain. It may also be necessary to rearrange the laboratory layout so that sunlight and laboratory lighting do not fall directly on the screen. If visual activity is prolonged and intensive, respite periods are essential. Operator should close eyes for 1-2 minutes.
Selection and installation of screen-based equipment
When installing Screen-Based Equipment (SBE) in the workplace, consideration should be given to: The furniture used with it; The accessories required to operate it appropriately; The layout of the equipment on the desk; The location of the furniture in the room. The Chair The chair is the single most important item of furniture and should have the following attributes: Castors to enhance mobility/maneuverability; 5 star base for stability; Adjustability – should be adjustable in seat height, back rest height and tilt and in forward/backward position of backrest. May have manual or gas lift adjustability depending on mode of operation and number of users; Cover – fabric. The Chair/Desk Combination The chair/desk combination should allow the user to achieve the following keying posture, within the ranges indicated by the dotted lines. Seat – Keyboard Height It is important to note that it is not so much the seat height and desk height per se that is important, but the distance between the top of the seat and the home row of keys. A seat that is too low, or a desk that is too high (eg, a laboratory bench) has the effect of increasing this distance. This puts increased strain on the arms and wrists. Raising the chair height will solve this problem, but may leave the legs
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No: PMDG: dangling, unsupported. Sometimes the desk will have a thick trim, edge or skirt under the front that makes it impossible to raise the chair up without squashing the thighs. Similarly, a seat that is too high for the desk will squash the thighs regardless of the thickness of the trim or skirt. In addition, it will encourage a stopped upper back posture, forward bending of the neck and cocked wrists. Leg Room Under The Desk There should be sufficient room under the desk for the legs to move and stretch freely. Drawers, shelves, or other obstructions restrict the ability of the operator to sit in close enough to the equipment. Consequently, the operator has to slouch forward to reach the keyboard. Visual Display Unit (VDU) Height VDU height is also an important consideration. This should be located so that the top of the screen is at eye level. (Exception: wearers of bifocals will need their screen much lower than average). This can be achieved by putting the PC, or some other ‘raiser’ (eg, wooden box) underneath the VDU, or by having an adjustable VDU platform/support arm built into or attached to the desk. A VDU that is too low will require the neck to be bent forward, whilst one that is too high has the opposite effect. Both increase the muscular strain on the neck and upper back. VDU – Eye Distance In choosing a desk for SBE, the VDU-to-eye distance must be considered. This will vary with personal preference and may range between 500-750mm. A desk that is too narrow will limit how far back the screen can be placed (especially if the VDU is very large). A screen that is too close will increase visual fatigue. This will differ depending on the number of pieces of equipment used and their necessary location, the number and size of documents used, the range of tasks performed at the desk and so on. When choosing a desk, consideration must be given to the amount of space required to allow correct posture to be maintained and to allow the work to be performed efficiently. Choosing an Appropriate Chair-Desk Combination The distance between the top of the seat and the home row of keys will differ with each individual depending on their body size and their preferred working posture. The selection of appropriate furniture must therefore take into account the number of people using the workstation, and the other tasks performed. The multi-user situation – When there is more than one operator using the workstation, the following should apply: A chair with gas operated adjustability of seat height and forward/backward position of the backrest is preferable to allow changes to be made quickly and easily.
A desk that allows the keyboard height to be raised and lowered (either by adjusting the height of the whole desk surface, or of a keyboard platform/tray in the desk) is preferable but not essential. Were there is no facility to adjust keyboard height (as above), a footrest
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No: PMDG: must be provided so that foot support is guarantee for the shorter users. A separate VDU platform or support arm that can be adjusted quickly and easily is preferable. In cases where the operators differ significantly in height, or where one or more operators wear bifocals, or where there is a high staff turnover, this feature is essential. The single-user situation – The furniture needs of the single user will depend on whether the operator is required to perform one task on one piece of equipment, or whether the job involves use of a range of different tasks/pieces of equipment. The latter would include situations where more than one computer is used, or where tasks such as typing, writing, or reception duties are performed. Single task/piece of equipment: In this situation, the user is doing one task continuously, and has little opportunity for variety of posture and movement. Particular attention should therefore be paid to the selection of furniture. The following recommendations apply: The chair should be manually adjustable for correct seat height and backrest position. Because quick and easy adjustability is not required, gas operated chairs are not essential. A desk that allows the keyboard height to be adjusted is preferable but not essential. Provided the operator can achieve the correct keying posture, a fixed height desk is adequate. If achieving the correct keying posture at a fixed height desk means the feet are left unsupported, a footrest is essential. Multiple tasks/pieces of equipment: Where one operator performs a number of different tasks (eg, writing, computing, typing) and/or uses more than one piece of equipment, the type of chair required will depend on the desk design. There are two options for desk design: Varying heights to suit the equipment/task, so that no adjustability of chair is necessary when moving from one to the other. In this case a manually adjustable chair would be adequate. The height of the4 desk is constant, so that more continuous free desk space is available and height adjustability is achieved by adjusting the chair. In this case, the chair should preferably be gas adjustable in height so that it can be quickly and easily changed to suit the task. Gas-operated adjustability of the backrest is not essential in most single-user cases. Accessories A range of accessories may be used at the workstation, including: Document Holder In all cases where source documents are referred to during keying, a document holder should be used. The purpose of the document holder
is to raise the source documents up from their low position on the flat surface of the desk to avoid excessive bending and rotating of the neck and to make reading easier. Document holders may have fixed stand that sits on the desk, or an
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No: PMDG: articulated arm that clamps to the back of the desk. Footrest This is only required where raising the chair to acquire the correct keyboard height means the feet are left unsupported. This is to be avoided because it places undue pressure on the underside of the thighs. Glare Guard Where reflectance on the VDU screen cannot be avoided, a glare guard (mesh filter) can be attached over the screen to improve contrast and reduce eye fatigue. However, some operators find the screen more difficult to read; hence the use of a glare guard is dependant on personal preference. Palm Rest A palm rest sits in front of the keyboard and provides a padded strip for resting the palms. It is NOT designed to support the palms whilst actually keying, but is there to provide a place to rest the palms during ‘micro-pauses’ (eg, when waiting for the computer to respond to a command, or while thinking about what to type next), rather than resting the palms on the sharp corner of the desk. The use of a palm rest is a matter of personal preference. Printer Hood Printers can be enclosed in printer hoods to reduce noise levels. These are very effective. However, they are expensive and take up a lot of space. If you are concerned about the adequacy of your SBE furniture/accessories, or you are thinking of purchasing new equipment/furniture/accessories, or you are experiencing pain or visual fatigue whilst working at your workstation, the Health, Safety and Environment Office is able to provide advice and perform an on-site assessment if necessary. In some cases, trials of chairs and accessories can be arranged. Layout of Equipment on the Furniture The ideal arrangement of equipment and materials will be determined by the tasks performed, their frequency and duration and the equipment used, visual requirements, reach distances and space allowances. As a general rule, the most frequently handled objects should be within easy reach when the elbow is resting on the desk top (optimum reach) and the less frequently handled objects should be placed within the distance reached by the outstretched arm (maximum reach). Positioning of the VDU and the document holder should be determined by which one is viewed as the primary object. If the source document is the primary object viewed (with touch typists), the document holder should be positioned in front of the keyboard user and the screen to one side.
If the screen and document holder are viewed equally, they should be placed side by side at the same height, in front of the user (alternatively, use a document holder which allows for positioning of documents in front and below the screen). If the screen is viewed most of the time, then the screen should be located in
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No: PMDG: front of the user and the document holder to one side. If desk space is limited, the computer (in most cases) can be stood up on its side under the desk. Location of Furniture in the Room Space considerations – Sufficient office space should be provided to allow safe and easy access to and from workstations. The layout/configuration of furniture needs to be considered carefully to optimize: Efficiency and comfort; Privacy and security; Communication and workflow; Unconstrained work postures and body movement; Flexibility and individual control; Social interaction. Where the operator uses more than one desk, L-shaped, U-shaped, end on end, or separated desks are just some of the possible configurations. Lighting Considerations – Where possible, workstations should be located so that the face of the VDU screen is at right angles to windows and light sources. Where this is not possible or where glare is still reflected on the screen, curtains or blinds should be used on windows. Ideally, workstations should be placed between and parallel to overhead lights rather than in front of and at right angles to them.
Version Date
1.0 4/09/06
Officer
Manager, Health Safety and Environment
Amendments
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