Health and Safety Risks of Laptop Computers
The aims of the project were: to determine the extent to which portable computers are used within organisations; to determine the extent of any health problems associated with portable computer use, and the risk factors involved, in comparison with full-sized display screen equipment (DSE); to identify the features of portables that were desirable and undesirable from the point of view of users' health and safety; and to identify the key features of good working practice with such equipment, including task design and user training requirements.
During the 1990s the Health and Safety Executive (HSE) had become aware that increasing numbers of people were using portable computers to carry out their tasks at work. HSE noted that reports of actual or possible problems associated with the use of portable computers appeared to be increasing. It was thought possible that the risks associated with desktop Display Screen Equipment (DSE) use (i.e. musculoskeletal problems, visual fatigue, etc.) could be exacerbated by the use of portable computer equipment. For example the design of portable computers includes some features (such as the lack of keyboard/screen separation) which may make them more difficult to use in a comfortable posture; and they are likely to be used in a range of different working environments, some of which may be poorly suited to computer use.
Aims and objectives of the research
HSE commissioned System Concepts to conduct research into the use of portable and handheld computers in UK organisations. The stated aims and objectives of the research project are given below:
- To determine the extent to which portable computers are used, who uses them, what types of machine they use, what kind of tasks they use them for, and under what circumstances they use them.
- To determine the extent of health problems associated with portable DSE, and the risk factors involved. How do these risk factors compare with those using full-sized DSE?
- To identify the features of portables that are i) desirable and ii) undesirable from the point of view of users’ health and safety, and to identify the key features of good working practice with such equipment (including task design and user training requirements).
We conducted desk-based literature and market reviews, and telephone-based research with health and safety managers in public and private sector organisations to:
- Determine the extent to which portables are used;
- Identify who uses portable computers;
- Identify the tasks they are used for and the working environment contexts in which they are used.
From the market review and the telephone survey it became clear that handheld computers represented a small proportion of the overall market (less than 2% of the overall PC market, including desktops, portables and handhelds). Therefore the focus of the research was shifted strongly towards the use of portable computers. Two organisations did employ relatively small numbers of people using handhelds, and some investigation was carried out with these users. Most of the observations made appeared to be highly dependent on the unusual tasks carried out, and the environments in which they were used.
For the main part of this research we developed a detailed eight-page questionnaire with which to match and compare desktop DSE users and portable DSE users. Not only did we wish to compare purely desktop DSE users with purely portable DSE users, but also to be able to compare both of these types of user with those portable DSE users who used 'docking stations' i.e. a portable computer with a separate full sized screen and/or keyboard attached. We were interested in this comparison because, in theory, the use of docking stations is widely regarded as good practice for the safe use of portables when they are in prolonged use at a workstation.
We used the results of a pilot test to refine the data collection materials and the analysis techniques. During our telephone research, we identified five organisations which employed groups of people using different types of computer equipment, i.e. standard desktop DSE and portable or handheld DSE. The questionnaires were administered to a sample of people within these groups. The returned questionnaires provided the basis for statistical comparisons between desktop users, portable users, and docking station users.
Although user questionnaire data provides much valuable information, self-report data can be subject to various sources of bias. We used supplementary interviews and observations conducted by qualified ergonomists as part of the research to identify features of portable equipment and the environments in which they are used which are undesirable or desirable from the point of view of users' health and safety. Key aspects of task design, break patterns, and other working practices were explored, in discussions with users, with health and safety personnel, and through our ergonomists’ observations.
In brief, our main findings are as described below. In general use, we found no differences in the reported experience of discomfort between portable users, desktop users and docking station users. We found a strong correlation between discomfort and hours per week spent using any computer, and hours per week spent using a desktop, but no significant correlation between discomfort and hours/week using a portable. However, typical portable computer users operated their machines 'alone' (i.e. without attaching it to an external keyboard, screen or 'docking station') for considerably fewer hours per week than desktop users, making direct comparisons difficult.
The proportion of working time spent using a computer showed a strong correlation with discomfort and appeared to be a useful predictor of discomfort for all types of computer use (desktop, portable and mixed use). Frequent breaks (or changes in task activity) and having training relevant to working with computers appeared to provide benefits for both portable and desktop users. Furthermore, the use of docking stations with portable computers appeared to reduce some of the reported discomfort associated with general computer use.
However, certain aspects of portable computer use seemed more likely to be associated with an increased risk of musculoskeletal discomfort than others. For instance, use in non-ideal locations (which encourage poor posture) such as motor vehicles and hotels, and manual handling issues such as carrying large amounts of paperwork, or carrying several additional items with the portable, were associated with discomfort. Users' own comments supported this quantitative data, in particular their wish for lighter portables (and accessories) and their concerns about back and shoulder discomfort.
How can you reduce the risks? The first set of recommendations outlines points to bear in mind when selecting or designing portable computers, the second group consists of points to bear in mind when planning tasks and training users of portable computers. These recommendations are drawn from the combined quantitative and qualitative results of the questionnaire survey, our site visits and workstation assessments, other available literature, and our ergonomics expertise. Detailed explanations of each recommendation are given in Chapter 17 of the full report, which can be obtained from HSE.
Points to bear in mind when designing or selecting portable computers
- Design portable computers with screen/keyboard separation and screen height adjustability
- Select new portable computers with ergonomic features in mind, including:
- As low a weight as possible (e.g. 3kg or less) for portable computer and accessories
- As large and clear a screen as possible (e.g. 14" diagonal or more)
- Detachable or height adjustable screen
- As long a battery life as possible, or extra transformer/cable sets so the user has a set in each main location where the portable is used, and only carries the computer, not the cables etc
- Touch pad, rollerball or external mouse rather than 'nipple' trackpoint device
- Wrist pad between keyboard and front edge of portable
- Lightweight non-manufacturer-branded carrying case with handle and shoulder straps
- Tilt adjustable keyboard
- Facility for attaching external mouse and numeric keypad
- Friction pads underneath to prevent computer sliding across surfaces when in use
- Sufficient memory and speed (for the applications used)
- "Add-ons" that improve usability and reduce maintenance time, such as (removable) CD-ROM drives and additional memory.
- Enhance battery life (without increasing battery weight) and improve battery management for portable computers
- Reduce the weight of the portable computer and its accessories
- Minimise the use of trackpoint ("nipples") as input devices.
Points to bear in mind when planning tasks and training users of portable computers
- Ensure that all staff who use computers (portables, desktops, docking stations, handhelds) receive health and safety training relevant to computer use
- Ensure that managers of portable computer users receive health and safety training relevant to portable computer use
- Provide guidance on setting up and using a docking station; and provide advice on using a portable computer when a docking station is not available
- Ensure that staff who use portables are encouraged to report any symptoms of discomfort that may be associated with their use of portable computers as soon as they arise
- Take regular breaks from computer use
- Ensure that organisations, managers and staff are aware of the increasing risk of discomfort associated with increased computer use
- Provide manual handling training for users of portable computers
- Carry out manual handling risk assessments with portable computer users
- Ensure that staff who use portables only use portable computer equipment when out of the office, or when a docking station is unavailable
- Provide good facilities such as external keyboards and monitors, (or ‘full’ docking stations) at workstations where portable computers will be in prolonged use
- Minimise the use of portables in non-ideal locations
- Ensure that handheld computers are carefully selected for ergonomic features which match the requirements of the tasks undertaken.
Tanya Heasman, 4-Oct-2001