Final Report on
Use of Notebook Computers and Related
Ergonomics and Occupational Safety and
Health Problems
2009
Occupational Safety & Health Council
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Content
Page No
1.
Executive Summary
3-7
2.
Research Background
7-8
3.
Research Rationales
9
4.
Strategies for Completing the Study
10
5.
Stage 1: Expert Interviews on Utilization of Notebook Computers
in Industry
11-19
6.
Stage 2a: Territory Wide Telephone Survey on Utilization of
Notebook Computers
20-36
7.
Stage 2b (Part 1): Field Survey on Utilization of Notebook
Computer by Adult Workers
37-58
8.
Stage 2b (Part 2): Telephone/ Online Survey on Utilization of
Notebook Computer
59-67
9.
Stage 3: Recommendations and Development of Handbook of
Good Practices
68-83
10. Project Conclusion
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84-88
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
EXECUTIVE SUMMARY
1.
Background
Nowadays the use of desktop and notebook computers are very popular in the workplaces.
For notebook computers, its mobility provides great convenience to the users. However, due to
its design characteristics (e.g. keyboard cannot be detached from the display screen), users may
experience difficulties in maintaining a healthy posture when using it, and may experience
musculoskeletal discomforts or other health problems after prolonged use. Therefore, the
Occupational Safety and Health Council commissioned Professor Chetwyn C.H. Chan of
Department of Rehabilitation Sciences of The Hong Kong Polytechnic University and his
Ergonomic and Human Performance Laboratory to conduct a research on utilization and its
related issues on notebook computers in Hong Kong in late 2007. The objective of this research
is to gain an understanding on the utilization situations of notebook computers and the associated
Occupational Safety and Health (OSH) issues among the notebook computer users, and then
suggest recommendations for enhancing the occupational safety and health for the use of
notebook computers.
The research was conducted between October 2007 and February 2009. There were three
stages. Stage 1 was interviews of OSH experts, employers and notebook computer users on
utilizations of notebook computers and their associated problems. Stage 2 was to launch a Hong
Kong wide telephone survey on the utilization patterns and health-related issues associated with
usage of notebook computers. The Survey covered adult workers and school-age children, and
findings were substantiated by conducting anthropometric measurements on selected notebook
computer users under real work environment. The data would enable us to identify the personal
and/or work factors which could attribute to the problems such as musculoskeletal discomforts
reported as experienced by notebook computer users. Stage 3 was to conduct focus group
interviews with which recommendations on promoting occupational safety and health of notebook
computer users were generated.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
2.
Findings
Sample Size
According to Comrey and Lee (1992), the adequacy of sample size can be defined as: N=100 is
poor, N=200 is fair, N=300 is good, N=500 is very good, and N=1,000 or more is excellent.
Another criterion used is Gorsuch (1983) of which the minimum sample size for 86 items covered
in this study would be 430. The sample size of the telephone survey conducted in Stage 2a is 500600 for each of the working adult and school-age children groups. The results obtained based on
the working adult or school-age children group can therefore be regarded as having an adequate
sample size and of “good” validity. It is important to note that the results obtained for the subgroups such as those who reported using notebook computer versus those who did not, or those
reported having high level of discomfort versus those who did not, might suffer from inadequate
sample sizes. Readers should be cautious when interpreting the results and the conclusion drawn
from the analyses at the sub-group level (see limitations of study). Nevertheless, the sample size
of the field assessment (N=100) conducted in Stage 2b on the use of notebook computer,
anthropometric measurements, and bodily discomfort can be regarded as adequate as the data
generated was based on one-on-one assessment. The criterion used is 30 subjects for small group
study (Portney and Watkin, 2009). The results obtained in the field assessment are regarded as
having an adequate sample size and of “good” validity.
In Stage 1, a total of 57 participants were successfully interviewed out of making 532
contacts by the research team. The participants were recruited mainly from: (1) finance, insurance,
real estate and business; (2) social, community and personal services; (3) wholesale and retail; and
(4) logistic, storage and communication. The participants in this stage were experts in OSH,
representatives of employers, and notebook computer users.
The results from the interview
indicated that usage of notebook computers was largely different from before. Nevertheless, the
conventional functions to be supported by notebook computers such as short duration, out of
office usage, and presentation and emailing did not seem to be the only utilization purposes
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
among the users. Rather, notebook computers were reported to be used for prolonged typingrelated functions such as word processing, surfing the Internet, information search, and data entry.
Besides the decision of selection, notebook computers could be selected because of limited
desktop space in offices and/or administrative directives of companies. The interviews of the
participants did not reveal obvious problems associated with usage of notebook computers. For
instance, as reported by the participants, they did not aware of existence of musculoskeletal
discomforts, pain and work-related disorders among the users. The results obtained from Stage 1
were useful for setting the framework for Stage 2 of the research. The most important finding
was that utilization of notebook computers seems to scatter across different industries and has a
wide variety which tends to depend on preferences of the users and their companies’ procurement
policies.
The Telephone Survey conducted in Stage 2 was contracted out to the Public Governance
Program of Lingnan University. The Survey successfully interviewed 517 working adults and 503
school-age children.
The main finding was that notebook computers (34%) were still less
commonly used than desktop computers (66%) among the working adults in Hong Kong. It was
however important to note that about half of the adult respondents indicating using notebook
computes (51.1%) claimed using them for a prolonged period of time, i.e. longer than six hours a
day. The prolonged usage was further aggravated by the notion that these respondents used
notebook computers for typing-related tasks such as word processing (57.3%) and web browsing
(49.6%). Such utilization patterns were found to be slightly different from those who reported
using desktop computers in the Survey. The results indicated that musculoskeletal discomforts
commonly existed in the shoulder neck (26% of the working adults in the Telephone Survey
(N=517) and 77% in the Field Survey (N=100)), the wrist (14.5% and 29%), and the eyes (9.2%
and 50%).
The proportion of the respondents reporting having discomforts were found to
associate with the age of the respondents, the duration of utilization in particularly for longer than
six hours a day and more than two years, and the use for word processing (and Internet surfing,
data entry and presentation revealed in the field test). It was found that the discomforts also
would be aggravated if the users did not report using external accessories such as monitor,
keyboard and mouse and attending training sessions on occupational safety and health. In fact,
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
only very small portion of the respondents (11.8%) attended these training sessions. The findings
from the field assessments and the match between the users’ anthropometric dimensions and the
workstations further supported the findings. On average, the users’ eye-level was found to be
higher than the screen of the notebook computers by about 15cm (Min=1.5cm, Max=29cm). The
elbow height was on average lower than the desktop by about 6cm. The illumination was on
average higher than the common practices (i.e.300-500 LUX) which was 709.6 LUX. The
findings from the Survey and field assessment were consistent suggesting the potential of
developing musculoskeletal disorders among the notebook computer users. The analyses revealed
the close relationships between awkward posture, improper design of the workstations in
particularly outside the office environment, lack of training on proper use of notebook computers,
and bodily discomforts. This can be due to the fact that the current regulation is less easy for
applying to the use of notebook computers in particularly when these computers are mobile and
used both in- and out-of the office. The inadequate provisions of the workstations and improper
utilization of notebook computers are also the main attributes to the problems.
For school-age children, the percentage of use of notebook computers was less than the
working adults (16.5%).
The purposes for them to use notebook computers were word
processing (47.5%), web browsing (42.4%) and entertainment (35.6%). For health-related
problems, some of the school-age children reported discomforts in the shoulder and neck (16.9%),
eyes (13.6%), and lower back (10.2%).
3.
Good Practices and Recommendations
Based on the findings of this research, the research team suggested recommendations
which might help notebook computer users to lower the risk of having musculoskeletal- and other
occupational health-related problems. The principles underlying the Occupational Safety and
Health Regulation on Manual Handling Operations are to reduce the weight, distance and
duration for carrying with the notebook computer; encourage regular break during carrying; and
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
use ergonomic gadgets such as backpack or hand trolley.
The principles underlying the
Occupational Safety and Health (Display Screen Equipment) Regulation are to achieve a match
between the users’ anthropometric dimensions and the workstation; use ergonomic external
accessories (e.g. external keyboard, mouse, etc.); conduct notebook computer specific risk
assessments; encourage stretching exercises and taking rest breaks; and providing informative
training on proper use of notebook computers. Besides, having the potential users and their
employees to reconsider the needs for using and/or prescribing notebook computers in the
workplace is deemed crucial. The experience gained in this research is that in most circumstances
the use of notebook computers in offices was not likely to be necessary. What it means is that
employers should conduct a thorough needs assessment on notebook computers before prescribed
them to their employees. A decision tree was constructed and proposed in this report to facilitate
employers and users make a suitable decision when choosing notebook computers. Last but not
least, an adapted risk assessment form was constructed to facilitate employers and users to
identifying occupational health risks from using notebook computer, so that they can implement
relevant actions for lowering these risks.
RESEARCH BACKGROUND
With the rapid development of modern technology, personal computers (PC) have become
one of the most common used display screen equipment devices in a workplace. There are
numerous studies which reveal the associations between work-related musculoskeletal disorders,
occupational health and use of computer in particular when the usage is of extended period of
time (Bergqvist et al., 1995; Gerr et al., 2004; Leung et al., 2004; Tittiranonda et al., 1999; Sung
et al., 2003). However, these studies have been involved the use of desktop computer inside the
office, monotonous work content, and workers’ adopting a sustained sitting posture (Szeto et al.,
2002, 2005a, 2005b). The findings in general are using ergonomic features such as foot-rest and
keyboard, maintaining an upright posture with elbow and knee at a right angle, varied work
content, taking rest breaks and typing less than four hours per day (Leung et al., 2004; Sung et al.,
2003). The research has also shown that certain workers had tendencies to adopt abnormal
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
postures and muscle activity patterns which became habitual and contributed to their chronic
musculoskeletal problems (Szeto et al., 2005a, 2005b).
Nevertheless, the changes in the ways business and industries conducted have shaped the
ways which computers are used in the workplace. Because of globalization and concepts of
mobile business, workers nowadays rely more and more on notebook rather than desktop
computers. The main features which enable notebook computers to serve their purposes are that
they are small in size, relatively light in weight and have compact input devices. Because of its
portability and convenience, notebook computers are now commonly used by businessmen in
traveling or meeting out of office. Nevertheless, the popularities of notebook computers have
also created escalating concerns among the users. First and most of all, its small in size has led to
the fact that notebook computers are also commonly used inside offices. The indoor usage has
resulted in occupational health issues such as musculoskeletal pain and eyestrains (Blehm et al.,
2005). It is anticipated that as their sizes are smaller and the screen and keyboard hinged together,
the musculoskeletal problems arising from prolonged use of notebook computers will be even
more prevalent than that of desktop computers.
With a densely populated environment and a boom in economy, Hong Kong provides a
very limited office space and therefore there is an urgent need to study the utilization
characteristics and health consequences associated with notebook computer use.
There are
several overseas studies reported the use of laptop computers and their health-related issues.
These studies put their emphases on examining and comparing with the posture and muscle
activities involved in using laptop computer and those with the desktop computers on healthy
young adults (e.g. Straker et al., 1997; Szeto et al., 2002; Villaneuva et al., 1998). There are very
little published data available on the usage of notebook computers and their associated
occupational health problems. The findings may also not be readily generalized and used as
guidelines for the local industries due to differences in statutory regulations across geographic
regions and possible differences in usage habit across the user groups. The proposed consultancy
study would help to bridge these gaps.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
RESEARCH RATIONALES
Despite there are a few studies which addressed the utilization of notebook computers and
the problems associated with their use, their findings might not be applicable to Hong Kong. First
of all, comparing with that in overseas, the office space of Hong Kong is relatively small; there
would be a higher proportion of workers using notebook computers in offices. The prevalence of
occupational health problems such as musculoskeletal pain and eyestrains could be higher in Hong
Kong. Second, workers in Hong Kong would need to carry notebook computers with them when
they work outside office and rely mostly on public transportation and walking, it is likely that the
workers would experience more musculoskeletal problems related to the lifting and carrying of
the computers than other Western countries. Third, the Occupational Safety and Health (Display
Screen Equipment) Regulation has only been enacted in Hong Kong for less than 10 years, the
compliance of safety use of notebook computer could be relatively lower than that of overseas.
Last, there have been a few reviews and survey studies conducted on the utilization patterns and
occupational health problems associated with using desktop computers in the workplace within
the last 10 years; but very few concerning the use of notebook computers. All these factors
suggest the needs for conducting a systematic review and survey on the utilization patterns and
potential threats to occupational health of using notebook computers among the work force in
Hong Kong. This consultancy project is an attempt to tackle these issues.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
STRATEGIES FOR COMPLETING THE STUDY
In order to complete the study efficiently and effectively, we divided the study into three
stages. The thinking behind separating the study into three stages was that the consultancy team
needed to develop the ways to effectively narrow down its scope and put focus onto a few
occupational groups of which the workers were required to use more of notebook computers.
Within these groups, the workers would present with problems in occupational health.
A
knowledge-based focus would enable the team to explore the problems with a considerable depth
so that the results obtained would have a high level of validity. These results can then be used for
developing occupational health recommendations and good practices.
The three stages of the study were: 1) identify occupational groups (or industries) which
give the highest level of usage and potential for developing occupational health problems; 2) large
scale survey to review the utilization patterns, risks on occupational health, and potential
musculoskeletal and other work-related symptoms; 3) expert reviews on development of good
practices and recommendations of usage of notebook computers – both inside and outside offices
(Figure 1). The descriptions and methods of each of the three stages will be elaborated in this
report.
Figure 1 Schematic diagram summarizes the plan of the study
 Interviews and
Focus groups;
Literature Analysis
 Telephone Survey,
Site Interviews and
Field Testing;
Surveys
 Focus groups with
stakeholders
Occupational Safety and Health Council
Stage One
Identification of occupational groups with a
relatively high exposure
Stage Two
Review of utilization patterns and work-related
symptoms of school-age children & working
adult, and specifically conduct risk assessment
on working adults in the occupational groups
Stage Three
Recommendations and guidelines Development
for users of notebook computers
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
STAGE 1: EXPERT INTERVIEWS ON UTILIZATION OF NOTEBOOK COMPUTERS IN INDUSTRY
1.
Introduction
Nowadays, with continuous development of technology, functionality and mobility of
computer there is an increasing demand of notebook computers used at work. Using of notebook
computers at work does facilitate efficiency and effectiveness of work; however, there are
potential risks for the notebook computers users to develop various cumulative traumatic
disorders (CTD) or musculoskeletal disorder (MSD) (Blehm et al., 2005).
There is limited literature available in the study of occupational safety and health relating
to the use of notebook computers. The results and conclusions of these studies cannot be
generalized to the Hong Kong public and notebook computer users. This study attempted to
focus on workers in specific local industries or occupational groups who utilized notebook
computers.
2.
Methods
Focus groups and individual interviews were used to gather information in the utilization
patterns and work-related symptoms associated with notebook computers. Interviewees from
statutory groups and stakeholders from the different local industries or sectors were recruited.
The information gathered from these groups will be used to triangulate with the results obtained
from other parts of the study.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
3.
Results
The potential participants were randomly selected from the Yellow Page/ White Page
under different industries or from the contact list of different industrial associations. A total of
532 contacts had been made by means of direct emailing, telephone calls or visits. These parties
composed of companies, associations and unions across different industries, statutory and
professional parties, notebook manufacturers and retailers, and notebook users. Approximately
one-tenth (i.e. 10.7%) of those we had contacted agreed to be interviewed in the form of
individual or focus-group. The participants who agreed to be interviewed reporting using
notebook computers at their workplace were from the industries shown in Table 1 and Chart 1.
Table 1 Summary of Industries from which interviewees were recruited
Industry
No. of Participants (N=57)
1. Finance, insurance, real estate
and business services
2. Social, community and personal
services
3. Wholesale & retail
4. Logistic, storage and
communication
5. Constructions
6. Self- Employed
7. Import & export
8. Medical Practitioners
9. Hotel & Catering
10. Manufacturing
Total:
16 (28%)
10 (17.5%)
9 (15.8%)
6 (10.5%)
5 (8.8%)
4 (7%)
3 (5.3%)
2 (3.5%)
1 (1.8%)
1 (1.8%)
57 (100%)
Chart 1
Finance, insurance, real estate and business services
Social, community and personal services
Wholesale & retail
Logistic, storage and communication
Constructions
Self- Employed
Import & export
Medical Practitioners
Hotel & Catering
Manufacturing
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
The companies, which agreed to participate and be interviewed, came from 10 out of the
14 industry categories in Hong Kong. The results therefore cannot be claimed to fully reflect the
actual situation and the prevalence of notebook computer utilization in the local industries.
When the participants were asked about the purposes and functions of using notebook
computers at work, the results suggested that the ways notebook computers were utilized are
quite different from what would be expected. The conventional utilization of notebook computer
was mainly for facilitating communication in an occasion such as using PowerPoint in a seminar
or business conference, or emailing while one is out of the office environment such as a trip
overseas. The utilizations of the notebook computer by the participants are summarized in Table
2. Most of the participants reported that notebook computers were largely used for PowerPoint
presentation in all industries except import and export. There was a substantial proportion of the
participants reported using notebook computers for word processing (Table 2 and Chart 2). The
findings indicated that the participants would carry out prolonged-typing related tasks such as
word processing with notebook computers. This further suggested that the participants possibly
involving sitting in front of the notebook computers and perform on stationary and prolonged
tasks. The data, however, did not indicate whether these tasks were carried out when travelling or
in a prolonged manner.
Table 2 Summary of Purposes of Notebook Utilization across
Participants from Different Industries
Industry
PowerPoint
1. Finance, insurance, real estate and business
services
2. Social, community and personal services
3. Wholesale & retail
4. Logistic, storage and communication
5. Constructions
6. Self- Employed
7. Import & export
8. Medical Practitioners
9. Hotel & Catering
10. Manufacturing
No of Responses (N=57)
Occupational Safety and Health Council
Traveling
Email
7
Word
Processing
3
4
2
Internet
Browsing
0
3
1
3
1
1
0
0
1
1
18 (31.6%)
3
3
2
0
1
0
1
0
0
13 (22.8%)
1
2
0
3
0
1
1
0
0
12 (21%)
2
1
1
0
1
0
0
0
0
7(12.3%)
1
2
0
1
1
2
0
0
0
7 (12.3%)
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Chart 2
PowerPoint Presentation
Traveling
Internet Browsing
Documentation/ Word Processing
Emailing/ Communication
The relationships between the patterns of utilization and functionality of notebook
computers did not appear to be strong. The responses from the participants indicated that most
of the utilization of notebook computers involving different extent of using desktop computers.
One observation was that the participants chose to use notebook computers when they traveled
and worked overseas.
The participants further suggested that, inside the office, there were
environmental factors which increased the likelihood of using notebook computers. According to
the participants, the main environmental factor was limited desktop space inside the office. The
limited in space did not allow the set up of desktop computer workstations. The use of notebook
computers henceforth was treated as a solution for making computer work possible as notebook
computers were smaller in size than desktop computers. Another factor as expressed by the
participants who came from large size companies was that staff of senior rank tended to be
provided with notebook computers. The staff was expected to use these computers when they
traveled overseas. It is however important to know, as these high rank workers from large size
(or medium size) companies spent most of their workday meeting with clients, it was likely that
their utilization of notebook computers was for presentation and/or emailing rather than typingrelated tasks. In contrast, those front-line workers from small size companies tended to be
provided with notebook computers because of the limited work space in the office and the out-ofoffice duties. The needs for using notebook computers were therefore multi-factorial and likely to
be influenced by the size of the company, rank of staff, and task requirements. These factors were
further explored in the rest of this study.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
During the interview, the participants were also asked whether they were aware of the
occasions of which the employees had suffered from musculoskeletal discomforts or disorders due
to the use of notebook computers at the work place. It was consistent among the participants
that these problems did not seem to be obvious in the companies which they worked in. In other
occasions, the participants expressed that there were reports of musculoskeletal discomforts from
the employees; however, the difficulties they had experienced were that the majority of these
cases did not substantiate the causality of the discomforts which were solely caused by the use of
notebook computers. The common causes of the discomforts, as expressed by the participants,
were possibly due to prolonged sedentary work, improper work postures, heavy workload, lack
of exercises, or deterioration of health due to aging etc. As a few of the participants who had a
medical background alluded on the difficulties of making a confirmed diagnosis of work-related
musculoskeletal disorders related to use of notebook computers. The problems were further
complicated by the notion that the use of notebook computers in most circumstances might be
part of the work duties and it was the only instrument used for carrying out these duties.
When asked about the known occupational and health issues associated with using
notebook computers at work, the participants expressed that the problems had not been obvious
and common. Nevertheless, they expressed that they had experienced difficulties in applying
existing Occupational Safety and Health (Display Screen Equipment) Regulation for workers
using notebook computers; and also expressed uncertainties in term of conducting risk
assessments and guidelines for promoting safety and health to the notebook computer users. The
main concerns on the existing regulations from the participants were:

Difficulty in defining the number of hours of utilization by the “users” in particularly
when the computers were used outdoor and at home.

Difficulty in defining the term “workstation” for notebook computer users.

The weight and carrying of the notebook computers not included as part of the risk
assessment.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Last but not the least, there was one guiding question which tapped on the requirement for
any personal protective equipment or accessories for the notebook computer users. The most
frequently equipment items mentioned by the participants were:
1.
external keyboard and mouse
2.
external monitor
3.
notebook dock/ laptop riser/ platform,
4.
backpack or hand trolley
5.
availability of one set of desktop computer in addition to the notebook computer
The use of external mouse and keyboard was recommended as the participants commented
that the existing notebook computers were comparatively small in size than desktop computers,
and hence their keyboards were in proportion smaller than the conventional keyboards. Typing
on a small size keyboard might lead to poor wrist angle, i.e. radial deviation of wrist joint when
typing. Apart from the keyboard, the participants commented on the designs of the mouse of
notebook computers. The common designs are touch-pad with which, as they expressed, might
generate excessive sustained and sedentary movements of the upper limbs and strains on the
finger joints when compared with the conventional external mouse attached to desktop computers.
The use of external monitor was also recommended as the participants commented that
the screen of notebook computers was non-detachable. The fixed level of the screen (mostly at a
lower level than the users’ eyes) might lead to improper work postures and eye distance. They
expressed that this might lead to shoulders/neck and eyes discomforts. An external monitor was
believed to reduce the harmful effects and risks brought about by the design of notebook
computers because it is comparatively large in size and its height is adjustable for accommodating
varying eye-level of users.
The use of dock or notebook stand was also recommended for increasing the adjustability
of notebook computers for fitting the dimensions of the users. In general, a notebook stand raises
the height of the screen so for fitting the eye-level of the users. The drawback is that when the
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
eye-level is accommodated, the level for the input device such as the keyboard and mouse pad is
too high to the upper limbs. The participants further pointed out that if a notebook stand was
used, the risks associated with using the gadget might be higher when an external keyboard and
mouse were not prescribed. The higher the level of the keyboard and mouse is, the higher the
strain level acting onto the users’ shoulders and upper limbs would be expected. As a result, the
participants were mindful for making the external keyboard and mouse available to users when a
dock or notebook stand is used.
Last but not least, the participants mentioned the value of having a backpack for carrying
the notebook computers. In particular, they opined that a backpack was crucial if users’ primary
purpose of using notebook computers was for traveling from one place to another, and to
overseas.
According to their comments, they considered backpack as the most useful and
ergonomic-designed bag for holding notebook computers. The counter-arguments against using a
backpack were more on the appearance of the backpack and inconvenience for those who
attended official meetings and/or wearing formal dresses.
4.
Discussion
The results obtained in this phase of the study suggested that notebook computers are
likely to be utilized by employees in rather diverse industries; while the participants commented
that employees in the banking and financial industries could be relatively more often be prescribed
with notebook computers. Workers in the banking and financial industries are those who require
to work outside offices for exchanges and marketing, and thus are more likely to be equipped
with notebook computers for their daily operations. Another group of workers was senior rank
position and executives in the banking and financial industries who can be regarded as
conventional users, i.e. notebook computers used for making presentations and emailing.
Nevertheless, the findings of this study suggested that the utilization of notebook computer was
observed in diverse industries, and there was no one industry in which notebook computer were
dominantly used; it is therefore concluded that utilization of notebook computers is likely to be
industry independent.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
The preference of notebook computers to be used in a single or a few specific industries is
not obvious. It is likely that the utilization of notebook computers is not industry-specific but
company- and function-specific. The results indicated that utilization of notebook computer
tended to be driven by the specific functions of the job duties and how the notebook computers
facilitated them to deliver such functions. Notebook computers were also commonly used by
employees for out-of-office business transactions and presentations, or working overseas. From
the interviews with some participants, the use of notebook computers was found to be handy and
tidy, which enhanced the image of the professional or sales. Another major reason for using
notebook computer was that it made traveling easier because of its small size and mobility both
within and outside Hong Kong. These observations are further investigated and verified in the
Phase 2 –Telephone and Field Survey.
The results also suggested that employees working in small- and medium-size enterprises
(SMEs) were more likely to be prescribed with notebook computers when compared with their
large size company counterpart. This was because most of the SMEs had relatively limited
workspaces in the office, they had larger preference to prescribe a notebook computer for their
employees, which replaced their large size desktop computer, while large corporate did not seem
to share the same concerns.
The preliminary results indicated that there were relatively little concerns expressed by the
participants on health-issues associated with utilization of notebook computers. One problem was
that the participants were not sure whether the health problems experienced by the users were
attributable to the use of notebook computers at work. All the participants interviewed did not
reveal a single case of musculoskeletal disorders nor discomforts known to them associated with
the use of notebook computers. However, the medical practitioners, who were also interviewed,
expressed more concerns with notebook computers utilization.
They anticipated that
musculoskeletal disorders or at least discomforts would be fairly common among the notebook
computer users. They further explained that the problems might be due to the design of notebook
computers such as the non-detachable screen, narrow keyboard and /touch pad mouse. The
research team therefore proposed to conduct assessments of the musculoskeletal pain/discomfort
Occupational Safety and Health Council
18
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
and other health issues of the participants interviewed in the Field Test. It is anticipated that the
information gathered are useful in terms of resolving the observed discrepancies between the
medical practitioners and those of the industry.
The results from the interviews indicated that there were difficulties with implementing the
existing regulations on notebook computer users. The main problems rest on the differences
between the set-up and operations of notebook and desktop computers.
The participants
expressed their concerns with the uncertainty and applicability of the existing risk assessment
criteria to notebook computers.
Besides, they expressed the difficulties in assessors defining
whether an employee would satisfy with the criteria for a DSE “user”. It is because most of the
notebook computers are used intermittently, used without a fixed posture and workstation layout,
and carried from place to place inside or outside the work place. The participants also revealed
that notebook computers were used for functions similar to those of the desktop computers.
These were different from the conventional usage of notebook computers such as displaying
presentations and emailing. Notebook computers users reported using them for prolonged-typing
tasks such as word processing. These issues are important and to be addressed in the latter part
of this project, i.e. Field Survey and development recommendations for improving the
occupational health of notebook computer users.
Occupational Safety and Health Council
19
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
STAGE 2A: TERRITORY WIDE TELEPHONE SURVEY ON UTILIZATION OF NOTEBOOK
COMPUTERS
1.
Introduction
A territory-wide Telephone Survey was conducted to identify the prevalence of utilization
of notebook computers among the population of Hong Kong. In this phase of study, there were
two target groups, i.e. school-age teenagers (i.e. 12-18 years old) and working adults (i.e. 19-65
years old or above). The potential occupational safety and health risks associated with utilization
of notebook computers between these groups of respondents were studied.
2.
Method
Computer Prevalence Questionnaire
The Telephone Survey conducted was based on a custom-designed 30-items questionnaire.
Each interview took five to seven minutes to complete. The items covered socio-demographics
information including occupation, gender, age, education levels and working status. It also
covered preference and facts on utilization of the computers, i.e. type of computer use, duration,
place of utilization, and utilization of external devices. There were items covering health and
occupational safety concerns, i.e. areas of discomfort, utilization of ergonomics products, and
training etc. Several panel reviews were conducted to establish evidence on the content validity
of the items.
Occupational Safety and Health Council
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Respondents
Three sampling frames, i.e. school-age children (i.e. 12-18 years old) and adult workers
(i.e. 19-65 years old or above), locations (outdoor and indoor) and tasks involved (play or leisure,
studying or work) were used and the sampling size was set at about 1,000 with about 500
respondents were expected in each of the two sample groups. The Telephone Survey was
conducted by Public Governance Program, Lingnan University between 19 and 29 November,
2007. The respondents were selected with a two-stage random sampling method so as to ensure
representative of the samples. The first stage of random sampling began with using the Chinese
computer-aided-telephone interviewing (CATI) system to automatically generate phone samples
based on the Hong Kong Telephone Directory. The last two digits of the selected telephone
numbers were replaced by two random numbers. The second stage of random sampling involved
the selection of the eligible samples belonging to household telephone numbers. The eligible
samples of numbers were pooled and based on which the respondents were randomly drawn for
conducting the telephone interview. About 70% of the phone calls were made during nighttime,
and 30% during the daytime.
3.
Results
Response Rate
A total of 20,665 calls were made, in which 2,577 were effective calls and 1,020
respondents obtained, in which 503 school-age children (49.3%) and 517 working adults (50.7%)
completed the interviewed. The average response rate was 39.6% with 42.5% from the schoolage children and 37.3% from the working adults.
Demographic Characteristics of Respondents
Similar proportions of male and female (i.e. 49.3% and 50.7% respectively) from both age
groups were interviewed. They had secondary or above education levels, and mostly lived in the
New Territories (i.e. 50.9%). The detail characteristics of the respondents were summarized in
Table 3 and Chart 3. Among the working adults (50.7%), they came from diverse occupational
industries with the most from banking, finance, insurance, real estate and business services
industry (19.9%). Second to this were the community, social and personal services industry (17%)
Occupational Safety and Health Council
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
and import and export (7%), and transport, storage and communication industries (7%). The
“other” category (22.2%) was composed of workers who were self-employed or could not
classify themselves under a specific industry category.
Table 3 Summary of Demographic Characteristics of the Respondents
(N=1,020)
Age (Yr)
12-14
15-18
20-24
25-29
30-34
35-39
40-44
45-49
50-54
55-59
60-64
>65
No response
Gender
Male
Female
Education
Tertiary
Secondary
Primary/No formal Education
Other
No Response
Living (District)
Hong Kong Island
Kowloon
New Territories
Islands
No Response
%
(N=1,020)
School-age Children (n=503)
Working Adult (n=517)
16.3
27.6
15.1
7.2
8.5
7.0
8.6
3.9
2.9
0.9
0.5
0.1
1.4
Industry (n=517)
Banking & Finance,
Insurance, Real Estate &
Business Services
Community, Social and
Personal Services
Import & Export
Transport, Storage and
Communication
Construction
Retail
Manufacturing
Restaurant
Hotel & Boarding House
Electricity, Gas & Water
Wholesale
Agriculture & Fishing
Others
No Response
49.3
50.7
30.9
65.5
2.7
0.5
0.4
19.9
17
7.0
7.0
5.8
5.2
4.4
2.1
1.4
0.6
0.4
0.4
22.2
6.6
18.0
29.2
50.9
1.1
0.8
Chart 3
Male
Female
Occupational Safety and Health Council
%
49.3
50.7
Banking & Finance, Insurance, Real Estate & Business Services
Community, Social and Personal Services
Import & Export
Transport, Storage and Communication
Construction
Retail
Manufacturing
Restaurant
Hotel & Boarding House
Electricity, Gas & Water
Wholesale
Agriculture & Fishing
Others
No Response
22
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Preference of Types of Computers
In total, there were 74.6% of the respondents using desktop computers only while 10.8%
using notebook computers only (Table 4 and Chart 4). The rest of the respondents (14.6%) used
both computer types. Among them, 83.5% of the school-age children and 66% of the working
adults used desktop computer only at home or at work, while there were comparatively low
utilization of notebook computers only, i.e. only 8.3% of the school-age children and 13.2% of
the working adults using notebook computers. The proportions of respondents using notebook
computers in both age groups were largely comparable. There were 20.8% of the working adults
and 8.2% of the school-age children using both computer types.
Table 4 Percentages of Respondents Utilizing Desktop or Notebook Computers, or Both
Prevalence of Computer Types (N=1020)
Both Notebook and Desktop Computer
Working Adult
School-age Children
Both groups
Notebook Computer Only
Working Adult
School-age Children
Both groups
Desktop Computer Only
Working Adult
School-age Children
Both groups
%
20.8
8.2
14.6
13.2
8.3
10.8
66.0
83.5
74.6
Chart 4
90
80
70
60
50
40
30
20
Both Notebook and Desktop Computer
10
Desktop Computer Only
0
Working
School-age
Adult
Both groups
Children
Occupational Safety and Health Council
Notebook Computer Only
23
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Duration of Utilizing Computer
A total of 94.7% of the respondents (i.e. 96.5% and 92.8% of working adult and schoolage children respectively) reported using either types of computer for more than two years (Table
5). The working adults (41.6%) mostly used computers for longer duration, i.e. more than 6
hours/day while the school-age children (45.3%) mostly used only for 1-2.9 hours/day, and 33.2%
of the school-age children used them for longer duration, i.e. 3-5.9 hours.
No significant
differences in the years and duration of utilization were revealed between notebook and desktop
computer in both the adult and children groups.
Table 5 Duration of Utilizing Different Types of Computers for Both Groups
Years of Computer Utilization
of the School-age Children
> 1 Year
Notebook Computer
Desktop Computer
1 – 1.9 Year
Notebook Computer
Desktop Computer
> 2 Years
Notebook Computer
Desktop Computer
Duration of Computer
Utilization of the School-age
Children
< 1 Hour
Notebook Computer
Desktop Computer
1 - 2.9 Hours
Notebook Computer
Desktop Computer
3 – 5.9 Hours
Notebook Computer
Desktop Computer
> 6 Hours
Notebook Computer
Desktop Computer
Occupational Safety and Health Council
%
1.6
1.7
1.6
5.4
5.1
5.4
92.8
93.2
92.8
%
10.5
3.4
11.5
45.3
49.2
44.8
33.2
32.2
33.3
10.3
13.6
9.9
Years of Computer Utilization
of the Working Adults
> 1 Year
Notebook Computer
Desktop Computer
1 – 1.9 Year
Notebook Computer
Desktop Computer
> 2 Years
Notebook Computer
Desktop Computer
Duration of Computer
Utilization of the Working
Adults
< 1 Hour
Notebook Computer
Desktop Computer
1 - 2.9 Hours
Notebook Computer
Desktop Computer
3 – 5.9 Hours
Notebook Computer
Desktop Computer
> 6 Hours
Notebook Computer
Desktop Computer
%
1.4
0.8
1.6
1.7
0.8
2.1
96.5
98.5
95.9
%
6.0
3.1
7.0
24.2
22.1
24.9
27.9
22.9
29.5
41.6
51.1
38.4
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Purposes of Utilizing Computers among the Respondents
In the survey questionnaire, the respondents were asked to describe the purposes of using
either types of computer. The options of the purpose were: (1) Internet/ Web Browsing, (2)
Word Processing, (3) Information searching, (4) Graphic, (5) Email or Web conferencing, (6)
Data Entry, (7) Entertainment or Game, and (8) others.
Among the working adults, they used notebook computer for a wide variety of functions.
The results indicated those notebook computers were used for word processing (57.3%), web
browsing (49.6%), email/ Internet conferencing (23.7%) (Table 6). The utilization pattern for
notebook computers was found similar to that of the desktop computer users, i.e. web browsing
(50.3%), word processing (49.5%), and information searching (20.2%) which were the most
frequently performed functions (Table 6). The school-age children also used notebook computers
mostly for word processing (47.5%), web browsing (42.4%) and entertainment (35.6%), which
was also similar to those for desktop computer, i.e. web browsing (53.2%), entertainment (39.6%)
and word processing (27%). These findings further substantiate the notion that the notebook
computers are likely to be used for carrying out similar tasks as the use of the desktop computers
instead of serving their original purpose which is mobile and handy when working outside office.
Table 6 Purposes of Utilizing Computers for Both Groups
3 Main Functions of Computers
of the School-age Children
Notebook Computer
1. Word Processing
2. Web Browsing
3. Entertainment
Desktop Computer
1. Web Browsing
2. Entertainment
3. Word Processing
Occupational Safety and Health Council
%
47.5
42.4
35.6
53.2
39.6
27.0
3 Main Functions of Computers
of the Working Adults
Notebook Computer
1. Word Processing
2. Web Browsing
3. Email/ Internet Conference
Desktop Computer
1. Web Browsing
2. Word Processing
3. Information Searching
%
57.3
49.6
23.7
50.3
49.5
20.2
25
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Perceived Environmental and Ergonomics Characteristics Associated with Computer Utilization
The respondents were asked to rate on the awareness of proper workstation design and
posture, and satisfaction with the environment/ ergonomic characteristics, e.g. illumination which
interfered with their computer utilizations. Most of the respondents appeared to be aware of
environment/ ergonomic characteristics and were satisfied with the illumination, workstation
space, chair in use, and desktop layout (i.e. DSE devices placed in the front) (Table 7). However,
there was comparatively low number of people aware of “always sit with good posture” when
using either types of computer.
Table 7 Proportion of Respondents on Awareness of Workstation Design and Posture, and
Satisfaction with Environmental and Ergonomic Characteristics
Environment and Ergonomics
Factors of the School-age Children
Illumination
Notebook Computer
Desktop Computer
Workstation Space
Notebook Computer
Desktop Computer
Adjustable Chair
Notebook Computer
Desktop Computer
Sitting Posture
Notebook Computer
Desktop Computer
Desktop Layout
DSE devices placed on the same level
Notebook Computer
Desktop Computer
DSE devices placed in front of user
Notebook Computer
Desktop Computer
%
89.1
93.2
88.7
94.2
87.9
95.3
61.6
76.3
59.7
17.9
20.3
17.6
59.4
63.0
60.1
89.7
84.5
90.5
Environment and Ergonomics
Factors of the Working Adults
Illumination
Notebook Computer
Desktop Computer
Workstation Space
Notebook Computer
Desktop Computer
Adjustable Chair
Notebook Computer
Desktop Computer
Sitting Posture
Notebook Computer
Desktop Computer
Desktop Layout
DSE devices placed on the same level
Notebook Computer
Desktop Computer
DSE devices placed in front of user
Notebook Computer
Desktop Computer
%
90.5
93.1
89.9
87.6
85.5
88.3
73.9
71.8
74.6
28.4
26.7
29.1
66.0
79.4
63.1
84.9
84.4
86.0
Among the school-age children, there was a good proportion of them who reported
having satisfactory environment including illumination (89.1%), workstation space (94.2%) and
workstation layout (89.7%). Comparing to the working adult respondents, there was slightly
lower proportion of the school-age children reporting awareness of using adjustable chairs (61.6%)
Occupational Safety and Health Council
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
and proper desktop layout (i.e. DSE devices placed on the same level) (59.4 %). The smallest
proportion of the school-age children (17.9%) was found in having a proper sitting posture when
using computers. No significant differences were revealed in all these items between the desktop
and notebook computer users.
Among the working adult respondents, similar proportions of responses were observed as
the school-age children respondents. They were mostly satisfied with the illumination (90.5%),
workstation space (87.6%) and DSE devices placed in front of user (84.9%). Similarly, there
were a good proportions of the working adult respondents being aware of having adjustable chair
(73.9%) and desktop layout (i.e. DSE devices placed on the same level) (66%). They showed
lower awareness, however, on proper sitting posture (28.4%).
There were no significant
differences in the results on these items between the desktop and notebook computer users.
Computer-related Health Concerns
Both groups of respondents reported the commonest discomforts over the shoulders/neck,
(11.5% and 24.4% for children and adults respectively), the eyes (11.9% and 12%), the wrist
(3.4% and 15.1%), and the lower back (5.6% and 7%). The patterns of discomforts reporting by
the respondents were found not significantly associated with the types of computers used. There
was slightly higher proportion of the working adult respondents using notebook computer
reported discomforts in the shoulders/neck (26%) than those using desktop computers (23.8%)
(Table 8 and Chart 5). It is noteworthy that the respondents in both groups attributed the
discomforts reported in the interview to the prolonged hours using the computers (43.6%) and
improper sitting posture (35.4%). In another question for respondents from the working adult
group, there were only 11.8% of them reported that they had attended occupational safety and
health related training workshop, seminar or exhibition organized by their employers or
themselves, or acquired OSH-related information from browsing Internet or the Occupational
Safety and Health Council website (Table 9).
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 8 Regions of Bodily Discomfort Associated with Use of Computers
Reported by the Respondents
Health Characteristics of the
School-age Children
Eyes Strain
Notebook Computer
Desktop Computer
Shoulders/ Neck Discomfort
Notebook Computer
Desktop Computer
Lower Back Discomfort
Notebook Computer
Desktop Computer
Wrist Discomfort
Notebook Computer
Desktop Computer
Headache
Notebook Computer
Desktop Computer
Hand/ Fingers Discomfort
Notebook Computer
Desktop Computer
Upper Back Discomfort
Notebook Computer
Desktop Computer
Lower Limbs Discomfort
Notebook Computer
Desktop Computer
%
11.9
13.6
11.7
11.5
16.9
10.8
5.6
10.2
5.0
3.4
3.4
3.4
2.2
3.4
2.0
1.6
3.4
1.4
1.0
1.7
0.9
0.4
0.0
0.5
Health Characteristics of the
Working Adults
Shoulders/ Neck Discomfort
Notebook Computer
Desktop Computer
Wrist Discomfort
Notebook Computer
Desktop Computer
Eyes Strain
Notebook Computer
Desktop Computer
Lower Back Discomfort
Notebook Computer
Desktop Computer
Hand/ Fingers Discomfort
Notebook Computer
Desktop Computer
Headache
Notebook Computer
Desktop Computer
Upper Back Discomfort
Notebook Computer
Desktop Computer
Lower Limbs Discomfort
Notebook Computer
Desktop Computer
%
24.4
26.0
23.8
15.1
14.5
15.3
12.0
9.2
13.0
7.0
5.3
7.5
3.7
5.3
3.1
1.5
1.5
1.6
1.2
1.5
1.0
0.2
0.0
0.3
Chart 5 Reported musculoskeletal discomforts by respondents between
notebook and desktop
users
MSDs computer
in Each PC Type
of Adult
Lower Limbs Discomfort
Upper Back Discomfort
Headache
Hand/ Fingers Discomfort
Lower Back Discomfort
Eye Strain
Wrist Discomfort
Shoulder/ Neck Discomfort
0
5
10
Both Types
Occupational Safety and Health Council
15
Notebook
20
25
30
Desktop
28
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 9 Perceived Factors Leading to Bodily Discomfort
Factors perceived leading to discomfort
Hours using computers
Improper sitting posture
Resting
Workstation Design
Attending OSH-related training
Yes (Both Groups)
Working adults
School-age children
No (Both Groups)
Working adults
School-age children
%
43.6
35.4
6.1
4.3
8.6
11.8
5.4
91.4
88.2
94.6
Preference of Purchase of Computers
Most of the respondents considered hardware specifications and price of the computers as
the first two priority in their purchase of either type of computers. However, the working adult
group also considered the specification, functions and brand of computers; while there were
16.7% of the school-age children purchased their computer with comparatively less emphases on
these considerations (Table 10). It was surprising to find that there were only a small proportion
of the respondents from both groups considering desktop space and outdoor use upon their
purchase of the notebook computer (i.e. about 3% or less). There were also a few working adult
respondents considered risk and ergonomics factors in their purchase as well. Thus, there seems
no obvious determining attributes that lead to an absolute decision on purchasing a particular type
of computer.
Types of Computer Utilization in Different Industry
As reported by the adult working group, the five most common industries of those who
reported using notebook computers were: (1) Social, Community and Personal services (13.7%);
(2) Finance, Insurance Real Estate and Business services (12.1%); (3) Import & Export (5.3%);
(4) Logistic, Storage and Communication (4.7%); and (5) Wholesales and Retails (4.7%)
industries.
On the contrary, the five most common industries of those who reported using
desktop computers were: (1) Finance, Insurance Real Estate and Business services (9.6%); (2)
Social, Community and Personal services (7.6%); (3) Logistic, Storage and Communication
Occupational Safety and Health Council
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
(3.3%); (4) Import & Export (3.1%); and (5) Construction (2.7%) (Table 11). This further
suggested that the use of notebook versus desktop computers is industry-independent.
Table 10 Preferences of Purchase of Computers by Respondents in Both Groups
Computer Purchase Preference of
School-age
Specification
Notebook Computer
Desktop Computer
Price
Notebook Computer
Desktop Computer
Never considered
Notebook Computer
Desktop Computer
Function
Notebook Computer
Desktop Computer
Appearance
Notebook Computer
Desktop Computer
Brand
Notebook Computer
Desktop Computer
Trend
Notebook Computer
Desktop Computer
Desk Space
Notebook Computer
Desktop Computer
Discount
Notebook Computer
Desktop Computer
Need for outdoor use
Notebook Computer
Desktop Computer
Potential risk & ergonomics factors
Notebook Computer
Desktop Computer
Occupational Safety and Health Council
%
63.8
76.3
62.2
38.0
47.5
36.7
16.7
5.1
18.2
8.3
5.1
8.8
8.0
7.5
6.5
8.0
8.5
7.9
2.0
3.4
1.8
1.0
0.0
1.1
0.8
3.4
0.5
0.2
0.0
0.2
0
0.0
0.0
Computer Purchase Preference of
the Adults
Specification
Notebook Computer
Desktop Computer
Price
Notebook Computer
Desktop Computer
Function
Notebook Computer
Desktop Computer
Brand
Notebook Computer
Desktop Computer
Never considered
Notebook Computer
Desktop Computer
Appearance
Notebook Computer
Desktop Computer
Desk Space
Notebook Computer
Desktop Computer
Need for outdoor use
Notebook Computer
Desktop Computer
Trend
Notebook Computer
Desktop Computer
Potential risk & ergonomics factors
Notebook Computer
Desktop Computer
Discount
Notebook Computer
Desktop Computer
%
65.2
70.2
63.5
42.7
37.4
44.6
11.4
10.7
11.7
10.8
13.0
10.1
9.3
7.6
9.8
8.3
10.7
7.5
1.7
2.3
1.6
1.4
3.1
0.8
1.0
1.5
0.8
1.2
2.3
0.8
0.4
0.8
0.3
30
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 11 Proportion of Respondents Using Different Types of Computers in Different
Industries
Types of PC across industry
Social, community and personal services
Notebook Users
Desktop Users
Finance, insurance, real estate and business services
Notebook Users
Desktop Users
Import & export
Notebook Users
Desktop Users
Logistic, storage and communication
Notebook Users
Desktop Users
Wholesale & retail
Notebook Users
Desktop Users
Constructions
Notebook Users
Desktop Users
Manufacturing
Notebook Users
Desktop Users
%
13.7
7.6
12.1
9.6
5.3
3.1
4.7
3.3
4.7
2.2
4.2
2.7
2.1
2.3
Association between Demographic Factors and Musculoskeletal Discomforts
Further analyses were conducted on studying the associations (i.e. statistical relationships)
between various demographic factors with the occurrence of different musculoskeletal
discomforts. First of all, there were significant associations revealed between the discomforts in
the shoulders/neck and the age of the respondents (Chi-Sq(df=10): 22.844, p=.011) using
notebook computers (Table 12). It suggested that there was higher proportion of respondents
who were older (i.e. ~45% over 30 years old and 24% over 40 years old) reported having
discomforts in the shoulders/neck region. The finding was consistent with those obtained from
the Field Survey which is to be reported in the next section. No significant associations however
were found between gender of the respondents using notebook computer and their bodily
discomforts. These reflected that there might have some human factors, which might lead to
musculoskeletal discomforts in notebook computer users. However, it was also essential to
Occupational Safety and Health Council
31
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
identify other factors which also showed associations between various musculoskeletal
discomforts and utilization of notebook computer.
The daily duration of utilization was also found to be significantly associate with the
discomforts in shoulders/neck (Chi-Sq(df=3): 11.454, p=.010). This was supported by the results
that more than half of those (54.8%) who reported suffering from shoulders/neck discomforts
used notebook computer for more than 6 hours per day (Table 12). On the contrary, there were
much lower proportions of the respondents (<20%) using notebook computers for less than six
hours per day reported shoulders/neck discomforts.
The number of years of utilization of
notebook computers was found to significantly associate with the discomfort in lower back (ChiSq(df=2): 7.441, p=.024). The results indicated that more than 98% of those using notebook
computers had two years or longer of experience using the computers.
Table 12
Duration
Musculoskeletal Discomfort
Eyes
Chi-Sq
(p-value)
Shoulders/ Neck Chi-Sq
(p-value)
Upper Back
Chi-Sq
(p-value)
Lower Back
Chi-Sq
(p-value)
Wrist
Chi-Sq
(p-value)
Hand
Chi-Sq
(p-value)
Headache
Chi-Sq
(p-value)
6.460
.091
11.454
.010
.275
.965
1.829
.609
5.009
.171
.994
.803
.351
.951
Year
.685
.710
1.993
.380
.096
.953
7.441
.024
3.537
.171
.298
.861
.121
.941
Those who used word processing more often were found to be more likely to report
discomforts in the shoulders/neck region (Chi-Sq(df=1): 19.875, p<0.001). There were 57.6% of
the respondents who used notebook computers for word processing reported shoulders/neck
discomforts (Table 13). Comparing with other functions, there were fewer respondents reporting
shoulders/neck discomforts when they used notebook computers for web browsing (38.7%),
information searching (17.7%) or emailing (27.4%).
Occupational Safety and Health Council
32
Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 13
Functions
Internet Browsing
Chi-Sq
(p-value)
Word Processing
Chi-Sq
(p-value)
Graphic & Animation Chi-Sq
(p-value)
Data Entry
Chi-Sq
(p-value)
Information Search Chi-Sq
(p-value)
Emailing
Chi-Sq
(p-value)
Eyes
.154
.695
.587
.444
.225
.635
.041
.840
2.763
.096
.251
.616
Shoulders/
Neck
1.719
.190
19.875
.000
.752
.386
.610
.435
.277
.599
.828
.363
Upper
Back
.718
.397
3.400
.065
.032
.859
.197
.657
1.021
.312
.008
.930
Lower
Back
1.266
.260
1.339
.247
.124
.725
.149
.699
.451
.502
2.535
.111
Wrist
1.119
Hand
.093
.290
1.616
.405
.761
.077
.204
.254
.782
.614
.754
.747
.532
.686
.619
1.261
.663
.024
.287
.842
.248
.190
1.136
.513
.040
.390
.164
.524
.429
.098
.104
Headache
.261
1.537
.877
.215
Not using external devices was found to associate with various bodily discomforts. Firstly,
significant association was found between not using external monitor and the report of
discomforts in the shoulders/neck (Chi-Sq(df=1): 4.356, p=.037), the upper back (Chi-Sq(df=1):
7.681, p=.006), the wrist (Chi-Sq(df=1): 7.253, p=.007) and the hand (Chi-Sq(df=1): 9.330,
p=.002) (Table 14). The use of external monitor would enable users to adjust the height and
distance of the screen, whilst notebook computers could not be adjusted to suit the notebook
users and enhanced the working posture. The results showed that there were larger proportions
of respondents, when external monitor was not connected to the notebook computers, reported
discomforts in the shoulders/neck (93.5%), the upper back (75%), the wrist (89.7%), and the
hand (83.3%).
Similar effects were also observed in those respondents who did not use external keyboard
and mouse. There were associations between not using external keyboard and discomforts in the
upper back (Chi-Sq(df=1): 4.891, p=.027) and the wrist (Chi-Sq(df=1): 15.751, p<.001); and not
using external mouse and discomforts in the shoulders/neck (Chi-Sq(df=1):4.163, p=.041) and the
wrist (Chi-Sq(df=1):4.262, p=.039); and not using external storage devices, e.g. USB and hard
disk, and discomforts in the upper back (Chi-Sq(df=1): 8.489, p=.004) (Table 14).
These
revealed that most of those who suffered from the musculoskeletal discomforts had not used
external devices, i.e. keyboard, mouse or storage devices with their notebook computers. For
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
instance, among those who reported shoulders/neck discomfort, 97.8% did not use external
monitor and 89.1% did not use external mouse in their operation with notebook computer.
Eyes
Table 14
External Monitor
External
Devices
External Keyboard
External Mouse
Storage Devices
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
.144
.705
.000
.997
.282
.595
.050
.822
Shoulders/
Neck
4.356
.037
.210
.647
4.163
.041
1.630
.202
Upper
Back
7.681
.006
4.891
.027
.011
.915
8.489
.004
Lower
Back
.951
.329
.338
.561
.137
.712
2.433
.119
Wrist
7.253
Hand
9.330
.007
15.751
.142
.002
.678
.000
4.262
.410
.039
.651
.022
.372
1.226
.093
.707
.205
.797
2.821
Headache
.881
.497
.268
.481
Finally, from the analysis, it indicated that there were significant associations between not
attending OSH related workshop or not acquiring OSH related knowledge and onset of the
shoulders/neck (Chi-sq(df=1): 14.491, p<.001) and the wrist (Chi-sq(df=1):4.960, p=.026)
discomfort. Among those participants who had attended OSH related workshop or acquired
OSH related knowledge, there were comparatively fewer number of participants complaining
bodily discomforts, i.e. suffering from shoulders/neck and wrist discomforts.
4. Discussion
The results suggested that the proportions of respondents using notebook computers were
small, 8.3% of the school-age children and 13.2% of the working adults. Desktop computers
when compared with notebook computers were still predominantly used by workers in the
industries. The design of this study and the lack of the past studies did not allow us predict the
trend of using notebook computers between the working adults and school-age children in the
future. As more and more school-age children learn about computers and use them in schools, we
would anticipate increasing trends in the population (both school-age children and working adults)
of using notebook computers or both desktop and notebook computers in the future years. It
would be beneficial for conducting a follow-up study for example three years from now in order
to confirm these trends. Because of the relatively small proportion and hence small sample sizes
of notebook computer users yielded from this study, the interpretations of its results should be
cautious.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Findings from this phase of the study indicate that computers, disregarding the types, were
used for similar purposes such as word processing, web browsing by both working adult and
school-age children groups. These suggested that whether using notebook or desktop computers
did not associate with age of the users and purposes of use. Interestingly, the determining factors
of choosing to use notebook computers were found not to relate to the availability of working
desktop space and need for mobility of the computer. Rather, according to the results, using a
notebook computer or not tended to relate to pricing, promotional strategies of sales company,
and development of computer technology specific to the type of computer.
From the results of the survey, they revealed that the respondents, disregard the types of
computers, reported discomforts mostly in the shoulders/neck, the eyes and the wrist and the
lower back. There were a few factors which were identified to associate with the bodily
discomforts reported by the respondents.
First, the duration of daily use and the years of
notebook computer utilization were significantly associated with reported discomforts in the
shoulders/neck and the lower back. The longer the duration of daily use and the more the years
of utilization was, the higher the percentages of respondents reported experiencing discomforts.
The musculoskeletal discomforts had a mechanical origin and were aggravated by the utilization
of notebook computers. The results of the Survey indicated that notebook computers are mostly
used for prolonged-typing tasks such as word processing. Accumulation of daily and hence yearly
loads might strain the musculoskeletal system of respondents’ body resulting in discomforts.
These discomforts could develop into pain and ultimately work-related musculoskeletal disorders.
Nevertheless, the pain and disorders which were out of the scope of this study could draw no
conclusion on this aspect. Besides the duration of utilization, the respondents’ reported that they
tended to assume a strained posture and did not have much opportunity to access to information
on occupational health and safety. These factors were likely to attribute to the musculoskeletal
discomforts as reported by the respondents in the Telephone Survey. These factors were further
measured and analyzed for their relationships with musculoskeletal discomforts in the next section.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Second, musculoskeletal discomforts were found to associate with not using external
devices or ergonomic peripheral devices. The results seemed to suggest that the use of devices
such as external monitor, keyboard and mouse attached to the notebook computers could alleviate
the problems with musculoskeletal discomforts.
There were smaller proportions of the
respondents reported experiencing musculoskeletal discomforts when they used one or more than
one type of these devices than those who did not use them. In particular, those who used external
monitor and keyboard with the notebook computers would have lower proportion of reporting
discomforts in the upper back and wrist. These further supported the benefit of using ergonomic
devices together with notebook computers.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
STAGE 2B (PART 1): FIELD SURVEY ON UTILIZATION
WORKERS
1.
OF
NOTEBOOK COMPUTER
BY
ADULT
Introduction
This part of the study was to further collect data on the utilization patterns and prevalence
of OSH-related issues encountered by workers when using notebook computer at work. The
issues could be revealed by collecting data on occupational safety and health when workers were
using notebook computer in a naturalistic working environment.
It was anticipated that the pattern of using notebook computer would be different between
indoor and outdoor working environment. It was further anticipated that habits and preferences
of using notebook computer would be different among different industries and sizes of company.
To capture these characteristics, data from each participant involved both a structured survey
interview and field assessments were collected.
2.
Method
This study adopted three sampling frames for selecting the participants. They were the
occupational groups (N=5), company sizes (N=3) and utilization location (N=2). These sampling
frames gave a total of 30 groups. If each group was composed of ten participants, the total
sample size would be 300. In view of the fact that the information gathered could be saturated
rather quickly and the limited resources available to the research team, with the consent of the
OSHC, the target of data collection had been scaled down to 100 participants who would take
part in the face-to-face interview and field assessment.
When it was confirmed that the
information gathered had been saturated, the rest of the 200 participants were to be interviewed
via Telephone/ Online Survey.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
The potential participants were first contacted by e-mail which contained a description on
the project and a consent letter. A follow-up telephone call was made or the 2nd email was sent to
confirm the potential participants had received the information. The third email was sent to the
potential participants one week later to enquire whether they would accept the invitation of
participating in the study.
Three instruments were used to guide the face-to-face interview and field assessment.
They were the worker’s demographic and notebook computer utilization questionnaire, symptoms
checklist, and environment and occupational health assessments. The demographic and notebook
computer utilization questionnaire gathered demographic characteristics, nature of job tasks, and
patterns of utilizing notebook computers. This questionnaire took about 15 minutes to complete.
The work-related symptoms checklist was to obtain information about physical symptoms,
interventions required and impact on work and leisure activities. It had specific questions on
physical symptoms related to use of notebook computers. This questionnaire took 15 minutes to
complete. The environmental and occupational health assessments involved the use of gadgets
such as laser meter and lux meter to measure different environment elements which would have
impacts on the participants’ use of notebook computers.
Besides, the participant’s working
postures and physical layout of the notebook computers were recorded by photos (for later
experts review). The total time taken to complete this part of the assessments was 15 minutes.
The research personnel arranged to conduct the field assessment with the participants who
had agreed to participate. In the initial 30 minutes of the field visit, the participant completed the
demographic and notebook computer utilization questionnaire.
Upon completion of the
demographic and notebook computer utilization questionnaire, the participants were requested to
remain seated with their normal working posture with the use of the notebook computer.
The
research personnel then carried out the environmental and occupational health assessments. The
research personnel used the abovementioned gadgets to measure the environmental and
anthropometric data of the participants. At the same time, the research personnel made notes of
additional observations of the participants, and the workstation of the participants were
photographed. Finally, the participants were requested to complete the final questionnaire, which
focuses on the work-related symptoms.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
The data obtained from this stage enabled the research team to identify the issues
associated with participants’ using notebook computers.
The results formed the basis for
formulating recommendation for notebook users for the next stage of this project.
3.
Results
Response Rates
One thousand and eight hundred invitations were sent through emails to companies or
associations of different industries and a total of 160 visits were subsequently made to companies
or associations of which the human resource departments had indicated willingness to participate
in the study. There were 315 feedback obtained from the invitations (response rate = 17.5%).
Among them, 104 participants (33%) met the selection criteria and agreed to participate in the
interview and field assessments. The fairly low response rate is common to this type of the field
test research and this reflected that there were relatively small proportion of employees and the
fewer companies were using notebook computers (13.2% as revealed in stage 2a).
Demographic Characteristics of Participants
Among the 100 participants who completed the interviews and field assessments, there
were more female (63%) than male (37%). About 68% of them were between 30 to 39 years old.
The participants were employees at different ranks and levels, i.e. junior to senior levels of job
position. More than half of these participants (n=62, 62%) took up senior positions in their
companies. Their job positions ranked from junior clerk and general officer to assistant manager,
supervisor or director. These results were consistent with those obtained in Stages 1 and 2a.
There were higher proportions of participants (or respondents) who worked at senior ranks were
prescribed with notebook computers. The participants come from diverse industries: (1) Banking,
finance, insurance, real estate and commercial servicing (n=17, 17%), (2) Community, social and
personal servicing (n=37, 37%), (3) Logistic, storage and communication (n=27, 27%), (4)
Import and Export (n=15, 15%), and (5) Construction industry (n=4, 4%) (Table 14 and Chart 6).
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 14 Demographic Details of Participants
(N=100)
Gender
Male
Female
Age (Yr)
25-29
30-34
35-39
40-44
45-49
50-54
Education
Tertiary
Secondary
Primary/No formal Education
Living (District)
Hong Kong Island
Kowloon
New Territories
Islands
%
37.0
63.0
7.0
40.0
28.0
15.0
2.0
8.0
84.0
12.0
4.0
36.0
34.0
28.0
2.0
(N=100)
Occupation/ Industry
Banking & Finance,
Insurance, Real Estate &
Business Services
Community, Social and
Personal Services
Logistic, Storage and
Communication
Import & Export
Construction
%
17.0
37.0
27.0
15.0
4.0
Chart 6
Banking & Finance, Insurance, Real Estate & Business Services
Community, Social and Personal Services
Import & Export
Logistic, Storage and Communication
Construction
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Notebook Utilization Pattern of Participants
Most of the participants (n=87, 87%) reported that they had used notebook computers for
more than two years in their daily works.
According to the definition stipulated by the
Occupational Safety Health (Display Screen Equipment) Regulation, only 23% of the participants
were not considered as “DSE User” whilst a large proportion (n=41, 41%) of the participants
might fit to be considered as Users, i.e. they used notebook computers accumulatively for six
hours or more in a day (Table 15 and Chart 7). These findings were found consistent with those
revealed from the Telephone Survey that most of the notebook computers had had more than two
years’ of utilization and used notebook computers for six hours or more in a day.
There were 73% (n=73) reported using computers outside of the offices. These included
65% using the computers at home, 23% at office of clients, and 24% at restaurant or other
outdoor premises. There were another 16 % using notebook computers on the street or public
transport (Table 16 and Chart 8). These findings concurred with those obtained from the panel
review conducted in Stage 1.
When they were asked the reasons of using notebook computers at work, the majority of
the participants (66%) opined that it was because of their company’s decision of the purchase,
whilst only about one-third (34%) explained that it fitted the requirements for outdoor utilization
(Table 17 and Chart 9). Other reasons for purchasing notebook computers for use included better
performance (32%) and more competitiveness of the price (23%) than those of desktop
computers. When the participants were asked to make a free choice of the type of computers to
use at work, interestingly, there were more participants who preferred notebook (i.e. 61%) than
desktop computers (39%).
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 15 Notebook Utilization Patterns of Participants
(N=100)
Year of Utilization
<1
1 – 1.9
>2
Daily Utilization (Hour)
<2
2 – 3.9
4 -5.9
6- 7.9
>8
No response
%
Chart 7 Daily hour use
每日使用量(小時)
11.0
2.0
87.0
30
25
20
5.0
18.0
24.0
15.0
26.0
12.0
15
10
5
0
<2
2 – 3.9
4 -5.9
6- 7.9
No
不回應
Response
>8
Table 16 Locations of Notebook Utilization of Participants
(N=100)
Necessity for Outdoor Use
No
Yes
Locations of Utilization
Office
Home
Office of Clients
Other Outdoor Premises
On Street
On Transport
%
27.0
73.0
Chart 8
Transports
運輸工具上
On Street
街上
100.0
65.0
23.0
24.0
8.0
8.0
Occupational Safety and Health Council
Other
Outdoor
其他室外地方
Places
Clients’
Office
客戶辦公室
Home
住所
Office
辦公室
0
10
20
30
40
50
60
70
80
90
42
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 17 Preferences of Types of Computers by the Participants.
(N=100)
Preference
Company Decision
Need for Outdoor Use
PC Performance
Price
Purpose of PC
Brand
Desktop Space
No Consideration
Potential Harm
Ergonomic & OSH
PC Appearance
Trend
Discount
Reselection of PC Type
Notebook
Desktop
%
Chart 9 Reselection of PC Type
66.0
34.0
32.0
23.0
21.0
18.0
6.0
4.0
3.0
3.0
2.0
0.0
0.0
再選擇電腦種類
70
60
50
40
30
20
10
0
手提電腦
Notebook Computer
桌上型電腦
Desktop Computer
61.0
39.0
When the participants were asked on the functions of the notebook computer being
utilized, there were higher percentages of respondents using notebook computer for work
processing (74%), emailing (54.5%), and information search (52%) than other functions (2 to
35%) (Table 18 and Chart 10). These were also consistent with the results revealed in Stage 2a
and that notebook computers were reported as used for functions other than the conventional
functions such as displaying presentations and emailing. This further explained the phenomenon
that notebook computers would be used for a prolonged period of time because of involvement in
typing-related tasks.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 18 Preferences of Functions of the Notebook Computer
(N=100)
Functions
Word Processing
Emailing
Information Search
Internet Browsing
Data Entry
Presentation
Graphic & Animation
Game
%
74.0
54.5
52.0
35.0
33.0
33.0
2.0
0
Chart 10 Functions of utilization
80
70
60
50
40
30
20
10
0
Internet
Browsing
Word
Processing
Graphic &
Animation
Data Entry
Presentation Information
Search
Emailing
Anthropometric Measurements of the Notebook Users
Visit was paid and field assessment was conducted to each of the participants.
Anthropometric measurements were conducted on the participant and the “workstation” on which
the notebook computer was placed (refer to Pictures 1 and 2 for illustration).
Measurement
parameters included monitor height, desk height and keyboard heights. There were two sets of
measurements:
1) Parameters recorded when the participant assumed an actual working posture (defined
as A); and
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
2) Parameters recorded when the participant was instructed to position in a proper
position and posture according to ergonomic principles (defined as B).
The proper position and posture of the participant was obtained by asking the participants
to assume an upright posture sitting at a proper height with the level of the elbow at the level of
the keyboard and mouse and keep about right angles at the hip, knee and elbow before taking
measurements. The worker-workstation match results are defined as the discrepancy between the
measurements obtained from the proper position and posture and those from the actual position
(i.e. B – A) (see figures in Table 19).
Picture 1 Anthropometric Measurements conducted in Field Assessment.
Monitor height
Desk height
Keyboard height
Eye level
Elbow level
Ideal seat height
According to the results, the average actual monitor height of notebook computer used by
the participants were 102.07cm (actual monitor height = distance from floor to the top edge of
screen) (Table 19). The majority of the participants (61%) were 101-105cm. The average proper
eye level of the participants (equivalent to proper monitor height = distance from floor to eyes of
participants when sitting in a neutral and upright position on an office chair) was 112.46cm. The
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
mean worker-workstation monitor height mismatch, i.e. discrepancy between the proper and
actual monitor height, was 14.72cm (Min=1.5cm; Max=29cm). Majority of the participants were
found to fall within the monitor height mismatch of 10-14cm (22%) and 15-19cm (34%) in
particularly of 14cm (8%), 17cm (6%), and 19cm (9%). What the results indicated were that in
general the monitor height of the notebook computer was in a much lower position than the eye
level of the participants, which could contribute to the musculoskeletal discomforts of these
participants (to be discussed in later sections).
Apart from the monitor height, the desk and the seat heights are also important factors
contributing to the occupational health of the participants. The average actual desk height (actual
desk height = distance from floor to top of the desktop) of the participants using notebook
computer was measured as 74.61cm (Min=68.5cm, Max=77.2cm). The most common desktops
seen in the field assessments had the heights of 74cm (17%) and 75cm (37%). The average proper
desk height (distance from floor to the height of the elbow in a right angled position of the
participants when sitting in a neutral and upright position with both feet flat on the floor surface)
was 68.46cm (Min=59.8cm, Max=80cm). The mean worker-workstation desk height mismatch,
i.e. discrepancy between the proper and actual desk height, was 6.17cm (Max=16cm). As desktop
height is usually non-adjustable, majority of the participants henceforth would need to raise the
seat height by 5-9cm (54%). After raising the seat height, a footrest probable would be needed to
compensate for the discrepancies to ensure that workers’ feet can be placed flat on a stable
surface. This is particularly relevant to those who use notebook computer in an office
environment. On the same token, the heights of the keyboard and mouse were found to relatively
too high for the participants. The average actual keyboard and mouse heights (distances from
floor to the level of the keyboard and mouse placed on the desktop) were 76.28cm and 73.91cm
respectively. When compared with the average proper elbow height which was 68.46cm, the
mean worker-workstation keyboard and mouse height mismatches were 7.82cm and 5.45cm.
These indicated that the participants were in general working with keyboards and mouse which
were placed at an excessively high level. Besides, the average actual viewing distance of the
participants was measured as 62.97cm (Min=35cm, Max=90cm) and most of the participants
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
(59%) was found to sit in a slightly farther distance than the recommended viewing distance, i.e.
35 to 60cm.
Table 19 Summary of Anthropometric Measurements and Worker-Workstation
Mismatches (Proper minus Actual)
Min.
Max.
Mean
SD
Actual Measurements (A)
Monitor Height
Desk Height
Keyboard Height
Mouse Height
Seat Heights
Eye Distance
93.00
68.50
65.00
60.00
41.10
35.00
108.00
77.20
81.00
77.20
54.00
90.00
102.07
74.61
76.28
73.91
48.21
62.97
3.46
1.40
4.49
3.56
3.15
12.3
44.97
112.46
68.46
2.36
4.87
3.96
Proper Measurements (B)
Seat Height
Eye Level
Elbow Height
40.50
102.00
59.80
50.00
125.00
80.00
Recommended Adjustments
Seat Height Adjustment or
Recommended Foot Rest
0.00
16.00
6.17
3.94
Height
Monitor Height Adjustment
1.5
29.00
14.72
6.80
Note: Max.=Maximum, Min.=Minimum, SD=standard deviation; unit is in centimeter;
Worker-workstation match are defined as the discrepancy between the measurements
obtained from the proper position and posture and those from the actual position (i.e.
B – A)
The worker-workstation mismatches would lead to excessive bending of the neck and
elevation of the shoulders (see Pictures 2 and 3). When participants assumed a lower than proper
sitting position (i.e. the elbow height was much lower than the desktop height), the most affected
would be elevation of the shoulders when using the keyboard and/or mouse. Lower than a proper
sitting height would require accommodations in the elbow (more extended) and the wrist joints
(more bending). Other problems would include limited desktop space, inadequate wrist support
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
and notebook computers not placing in front of the participants. All these would pose risks on the
occupational health of users of notebook computers.
Pictures 2 Sampled participants’ postures when using notebook computers
Mismatches in height of monitor and eye level
Compact keyboard design resulting in unfavorable
wrist joint angles
Mismatches in desktop and elbow heights
Very limited desk space
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Pictures 3 Common Workstation Layout with Notebook Computer
Notebook computer positioned on a
computer rack with limited work space
Notebook computer positioned on side table
Notebook computer positioned close to edge
of table with insufficient wrist space
Notebook computer positioned on the corner
of work desk
Notebook computer positioned in front of
the user
Notebook computer positioned in front of
the user
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
The field assessments also measured the illumination level of the environment in which
notebook computers were used by the participants. The results of illumination revealed that the
average light intensity on the desktop was 709.6 LUX, which was above the recommended levels
of 300-500 LUX (Table 20). There were only one-fourth of the workstations (25%) illuminated
at the level commensurate with the recommended levels. Higher proportion of workstations (69%)
was higher than recommended levels. The light intensity measured on the keyboard (Mean=596.7
LUX) and monitor (Mean=416.4 LUX) fell within the recommended levels.
Table 20 Measurement of Light Intensity on Desktop of the Workstations
Minimum Maximum
Light intensity on the Desktop (LUX)
Light intensity on Keyboard (LUX)
Light intensity on Monitor (LUX)
249.00
185.00
133.00
1507.00
1193.00
815.00
Mean
709.6
596.68
416.40
SD
327.22
297.64
177.15
Use of Ergonomic Features and Participants’ Discomforts
The field assessment covered the type of ergonomic features which the participants
adopted when using notebook computers.
Among the 100 participants, none of them was
observed using a footrest or document holder at their workstation (Table 21 and Chart 11). From
the results, no significant associations were found between not using external monitor and mouse,
and no different MSDs were reported by the participants. However, significant associations were
revealed between not using external keyboard and the discomforts in the shoulders/neck (ChiSq(df=1): 4.150, p=.042), in which 70% of the respondents reported suffering from
shoulders/neck discomfort did not use an external keyboard; while the results obtained in the
Telephone Survey which also showed the use of external keyboard was associated with lower
chance of experiencing discomforts in the upper back and wrists. Significant associations were
identified between not using external storage device and the discomforts in the lower back (ChiSq(df=1): 14.823, p<.001) and the hand (Chi-Sq(df=1): 8.734, p=.003) (Table 22). Only 8.9%
and 26.7% of the participants reported experiencing discomforts in the lower back and hand when
external storage devices were used. In order words, the participants who did not use these
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
devices together with notebook computers tended to have higher chances of experiencing
discomforts over specific body parts.
Table 21 Summary of Use of Ergonomics Features / Accessories by the Participants
Types of Ergonomics Devices / Accessories
Mouse (External)
Storage (External)
Keyboard (External)
Monitor (External)
Printer
Adj Dock
OSH Products
Writing Pad
Chart 11
(%) (N=100)
92.0
45.0
40.0
26.0
25.0
15.0
13.0
7
100
90
80
70
60
50
40
30
20
10
0
Mouse
Storage Keyboard Monitor
(External) (External) (External) (External)
Eyes
Table 22
External Monitor
External
Devices
External Keyboard
External Mouse
Storage Devices
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
.208
.648
.667
.414
2.174
.140
.040
.841
Shoulders/
Neck
2.606
.106
4.150
.042
3.579
.059
.621
.431
Printer
Adj Dock
Upper
Back
3.259
.071
.155
.693
2.543
.117
.285
.594
OSH
Products
Lower
Back
.422
.516
2.116
.146
2.088
.148
14.823
.000
Writing
Pad
Wrist
.599
Hand
.493
.439
.032
1.087
.482
1.307
.857
.068
.253
.795
.151
.269
.215
8.734
.388
.297
2.062
1.535
.746
Headache
.604
3.780
.003
.052
When the participants were asked how they carried the notebook for work outside the
office, 46% of them carried it with a handbag, 32% with backpack, 19% hand-held the machine,
whilst 26% carried it with a single-side bag. Only a small proportion of the participants replied
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
that they used ergonomic accessories such as hand trolley (3%). There was significant association
between the use of handbag for carrying notebook computer and discomforts over the lower back
(Chi-Sq(df=2): 18.182, p<.001), the wrist (Chi-Sq(df=2): 6.609, p=.037), the eye (ChiSq(df=2):11.872, p=.003) and headache (Chi-Sq(df=2): 6.572, p=.037) (Table 23a). There were
more people with abovementioned bodily discomforts when handbag was used for carrying the
notebook computer. Despite there were significant associations between using handbag, and eye
discomfort and headache, the explanations for the phenomena are out of the scope of this study.
In contrary, significant associations were also found between not using backpack for carrying the
notebook computer and discomfort in the lower back (Chi-Sq(df=2): 22.529, p<.001), i.e. fewer
proportion of people (i.e. 22.2%) reporting low back discomfort when backpack was used. It
was noteworthy that there were significant associations between the use of hand for carrying
notebook computers and discomforts reported in the upper back (Chi-Sq(df=2): 6.998, p=.030),
and the lower back (Chi-Sq(df=2): 22.215, p<.001), i.e. more people suffering from these
discomfort if they carried notebook computer with hand. Not using single-side bag (26%) for
carrying notebook computers was found associated with the discomforts in the lower back (ChiSq(df=2): 19.325, p<.001) and the wrist (Chi-Sq(df=2):12.562, p=.002); and not using hand
trolley (3%) associated with discomforts in the upper (Chi-Sq(df=2):13.446, p=.001) and lower
back (Chi-Sq(df=2):18.266, p<.001) (Table 23a). These indicated that there were fewer number
of participants experiencing bodily discomforts when these two types of carrying bag were used.
There were 13.5% and 15.4% of participants, who had used single-side bag, reported discomforts
in the lower back and wrist respectively; and 16% and 18.7% of participants, who had used hand
trolley, reported discomforts in the upper and lower back respectively.
Eyes
Table 23a
Carrying Methods
Handbag
Backpack
Hand Carry
Singleside/Messenger
Hand Trolley
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
Chi-Sq
(p-value)
11.872
.003
.655
.721
1.079
.583
.336
.845
3.195
Occupational Safety and Health Council
.202
Shoulders/
Neck
5.661
.059
.559
.756
3.084
.214
4.749
.093
1.415
.493
Upper
Back
3.017
.221
4.086
.130
6.998
.030
1.921
.383
13.446
.001
Lower
Back
18.182
.000
22.529
.000
22.215
.000
19.325
.000
18.266
.000
Wrist
6.609
Hand
.957
.037
4.174
6.572
.620
1.927
.124
.248
.382
.884
.674
.002
.341
2.855
.615
1.452
.518
.163
2.149
.974
1.314
.037
3.631
.788
12.562
Headache
.240
1.031
.484
.597
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Notebook-related Health Characteristics
The common health or musculoskeletal problems reported by the participants are
summarized in Table 23b and Chart 12.
The most common discomfort expressed by the
participants was in the shoulders and neck regions (77%). Other areas of discomfort included the
eyes (50%), the upper back (29%), the lower back and wrist (28% and 22%). It was also
common to find participants reporting discomforts in multiple sites in the body. Only a small
proportion of the participants expressed that they had sought medical consultation (i.e. 18%),
whereas other 7% had sought consultations from Traditional Chinese Medicine or other
alternative type of treatments such as bone-setter, acupuncture or reflexology. The participants
self perceived that the causes of the bodily discomforts could be due to work (58%), lack of rest
(26%), and natural degeneration because of aging (12%).
Table 23b Bodily Discomforts Reported by Participants
Locations of
Discomfort
Shoulders and Neck
Eyes
Wrist
Lower Back
Upper Back
Hand
Headache
Lower Limb
Percentage of People
Reported (%)
N=100
77.0
50.0
29.0
28.0
22.0
15.0
3.0
3.0
Chart 12
80
70
60
50
40
30
20
10
0
Headache
Eyes
Shoulders/Neck Upper Back
Lower Back
Wrist
Hand
Lower Limb
Demographic Characteristics and Other Factors Related to Using Notebook Computers
Gender and Age by duration of utilization
From the Field Survey, the finding indicated that more male participants used notebook
computers for shorter duration, i.e. 2 to 3.9 (27%) and 4 to 5.9 (24.3%) hours/day; while more
female participants used notebook computers for longer hours per day, i.e. 4 to 5.9hr (23.8%), 6
to 7.9hr (15.8%) and
> 8hr (38.1%).
There were relatively more participants working
continuously up to 4-5.9 hour/day (24%) and accumulatively for more than 8 hours/day (26%).
Besides, most of the participants working with notebook computer for 4-5.9 or >8 hours/day
were those at age of 30-34.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Musculoskeletal Discomfort by Age and Gender
Age of the participants was found to have significant association with the discomforts in
the eyes (Chi-Sq(df=5): 24.9, p<0.001), the shoulders/neck (Chi-Sq(df=5): 19.288, p=.002) and
the upper back (Chi-Sq(df=5): 23.299, p<0.001) (Table 24). There were more participants at the
age of 30-34, 35-39 and 40-44 reporting discomforts in their eyes (15-17% versus 0-4%), the
shoulders/neck (13-37% versus 0-6%) and the upper back (4-10% versus 0%) than those of the
younger (i.e. 20-29) and older (45-54) groups. Gender was also found to associate with the
discomforts in the shoulders/neck (Chi-Sq(df=1): 7.301, p=.007) and the wrist (Chi-Sq(df=1):
14.250, p<.001). Female participants were more likely (85.7%) than the male (62.2%) reporting
such discomforts. No significant associations were found between the gender and the discomforts
in the other body parts. The discomforts in the shoulders/neck region (Chi-Sq(df=5): 23.844,
p<0.001) and the hand (Chi-Sq(df=1): 12.472, p=.029) were revealed to significantly associate
with the duration of using notebook computer. In general, the participants who reported using
notebook computers for 4-5.9hr/day or >8hr/day (i.e. 28.6% and 30%) were more likely to report
discomforts in the shoulders than those working for 2-3.9hr/day (15.6%) and 6 or 6-7.9hr/day
(13%).
Table 24
Age
Musculoskeletal Discomfort
Eyes
Chi-Sq
(p-value)
Shoulders/ Neck Chi-Sq
(p-value)
Upper Back
Chi-Sq
(p-value)
Lower Back
Chi-Sq
(p-value)
Wrist
Chi-Sq
(p-value)
Hand
Chi-Sq
(p-value)
Lower Limb
Chi-Sq
(p-value)
Headache
Chi-Sq
(p-value)
Occupational Safety and Health Council
24.90
Gender
1.073
.000
19.288
6.943
.300
7.301
.002
23.299
.007
.005
.000
9.616
.944
.394
.087
9.711
.530
14.250
.084
6.573
.000
.102
.254
4.639
.750
1.816
.461
4.693
.178
1.816
.461
Duration
.178
.225
23.844
.000
2.769
.736
12.596
.027
5.094
.405
12.472
.029
8.803
.117
9.794
.081
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Musculoskeletal Discomfort by Utilization Functions
The use of notebook computers for specific utilization was also found to associate with
bodily discomforts. Browsing the Internet (35%) was significantly associated with the discomforts
in the lower back (13%; Chi-sq(df=1): 5.024, p=.025), the wrist (15%; Chi-Sq(df=1): 5.022,
p=.025;), the hand (10%; Chi-Sq(df=1): 7.778, p=.005;) and the lower limb (3%; Chi-Sq(df=1):
5.744, p=.017) than those who did not (Table 25). Those who used notebook computer for word
processing (74%) were more likely to report discomforts in the wrist (27%) (Chi-Sq(df=1):7.747,
p=.005) than those who did not. Performing data entry was found to associate with discomforts
in the lower back (Chi-Sq (df=1):10.252; p=.001) and the hand (Chi-Sq(df=1):8.692, p=.003), i.e.
33% of participants, who had used notebook computer for data entry, reported discomfort in the
lower back. Similarly, using notebook computer for information search was found to associate
with discomforts in the eyes (Chi-Sq(df=1): 5.769, p=.016) and presentation with the wrist (ChiSq(df=1): 12.588, p<.001), i.e. 52% of participant, who had used notebook computer for
information search, reported discomfort in the eyes. And there was no significant associations
found with other utilization functions.
Table 25
Functions
Internet Browsing
Chi-Sq
(p-value)
Word Processing
Chi-Sq
(p-value)
Graphic & Animation Chi-Sq
(p-value)
Data Entry
Chi-Sq
(p-value)
Presentation
Chi-Sq
(p-value)
Information Search Chi-Sq
(p-value)
Emailing
Chi-Sq
(p-value)
Eyes
3.560
.059
.208
.648
2.041
.153
.045
.832
2.216
.137
5.769
.016
2.576
.108
Shoulder/
Neck
.224
.636
.282
.595
.610
.435
3.291
.070
1.713
.191
3.548
.060
1.513
.219
Upper
Back
.023
.879
.496
.481
.576
.448
1.979
.160
.798
.372
2.959
.085
1.946
.163
Lower
Back
5.024
.025
.134
.715
.794
.373
10.252
.001
2.355
.125
1.183
.277
.706
.401
Wrist
5.022
Hand
7.778
.025
7.747
.005
.493
.005
4.996
.482
.360
.025
.071
.548
8.692
.789
12.588
.003
.001
.000
3.239
.976
.452
.072
1.071
.501
.003
.301
.955
Lower
Limb
5.744
.017
1.087
.297
.063
.802
1.523
.217
1.523
.217
2.855
.091
3.631
.057
Headache
1.665
.197
1.087
.297
.063
.802
6.279
.012
1.523
.217
2.855
.091
3.631
.057
Predicting Musculoskeletal Discomfort among the Participants
Age, gender, duration of utilization, locations of utilization, utilization functions, notebook
carrying methods and types of external devices used were entered as predictor variables for
conducting regression analysis. The outcome variable was the reported discomfort in one region
such as shoulders/neck, or the eyes.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Age of the participants was identified as a significant predictor of discomforts in the eyes
(=44.7, p=.013) which accounted for 6% of the total variance. Duration of utilization was also a
significant predictor of shoulders/neck discomforts (=-.466, p=.007) accounting for 7.1% of the
total variance.
Using notebook computer for working at home (n=65 out of 100) was a
significant predictor of discomfort in the eyes (=.992, p=.020; 5.2% of total variance). Similarly,
using notebook computer for working at other outdoor places (n=24 out of 100) was also found
to significantly predicting discomfort in the eyes (=1.152, p=.018; 5.5% of total variance),
shoulders/neck (=1.435, p=.034; 4.4% of total variance), wrist (=1.003, p=.042; 4% of total
variance) and upper back (=1.338, p=.011; 6.3% of total variance).
Specific function of utilization was also found to be a predictor of particular bodily
discomfort. Internet browsing (n=35 out of 100) was found to be a predictor of wrist discomfort
(=1.005, p=.027; 4.8% of total variance), and lower back (=-1.19, p=.020; 5.3% of total
variance), hand (=1.569, p=.006; 7.1% of total variance). Besides, word processing was found
to be a predictor of wrist discomfort (=1.931, p=.002; 8.8% of total variance). PowerPoint
presentation was a predictor of hand discomfort (=-2.348, p<.001; 13.9% of total variance.
Information search predicted eyes discomfort (=.981, p=.016; 5.7% of total variance).
Musculoskeletal Discomfort associated with Work Desk Dimensions
The dimensions of the workstation, seating chair and other accessories were measured.
Correlations were computed between these dimensions and the report of musculoskeletal
discomforts in different parts of the body. The dimensions included monitor height (measured
from floor to the top edge of monitor), desk height (measured from floor to the desk surface),
original seat height (the distance between the seating surface and floor), and the seat adjustment
height/ recommended foot rest height, eye distance (distance between eyes of participants and the
top edge of the monitor of the notebook computer) and illuminations of the workstation
environment. In the analyses, the eye level discrepancy (discrepancy between the top edge of
monitor and appropriate eye level of participants), the eye distance discrepancy (deviation from
the recommended level, i.e. 35-60cm) and elbow discrepancy (discrepancy between desk height
and the appropriate elbow height of participants) were used.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Eyes Discomfort vs. Work Desk Dimensions
The reported discomfort in the eyes were found to significant associate with the eye
distance discrepancy (Chi-Sq(df=4): 9.615, p=.047), eye level discrepancy (Chi-Sq(df=5): 18.165,
p=.003), and level of illuminations (Chi-Sq(df=6): 26.263, p<.001). In general, participants who
had larger monitor height discrepancy (58%, 16 cm or more), and the lower (56%, <600 LUX) or
higher (22%, >1000 LUX) level of illumination were more likely to report discomforts in the eyes.
When these variables were entered into a regression equation for predicting discomforts in the
eyes, the eye distance discrepancy (=.434, p=.006; 7.3% of total variance) was found to be the
most significant predictor.
Shoulders/Neck Discomfort vs. Work Desk Dimensions
Significant associations were found between the eye distance (Chi-Sq(df=4):19.290,
p=.001) and illumination discrepancy (Chi-Sq(df=6):20.646, p=.002) with the shoulders/neck
discomfort. In other words, the larger the discrepancies in the eye distance (16.9%), and the
illumination level below 500 LUX (29.9%) or above 1000 LUX (22.1%) were, the more likely the
participants reported discomforts in the shoulders/neck discomfort (77% versus 23%).
Upper Back Discomfort vs. Work Desk Dimensions
Significant associations were found between the elbow discrepancy (Chi-Sq(df=3): 11.007,
p=.012), eye level discrepancy (Chi-Sq(df=5): 13.954, p=.016) and illumination discrepancy (ChiSq(df=6): 12.712, p=.048) with the upper back discomfort. The larger the discrepancies in the
elbow distance (i.e. >6cm) were, the more likely the participants experienced upper back
discomfort (68.2% versus 31.7%).
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Lower Back Discomfort vs. Work Desk Dimensions
The eye distance discrepancy (Chi-Sq(df=4): 14.241, p=.007), elbow discrepancy (ChiSq(df=3): 13.049, p=.005) and illumination (Chi-Sq(df=6): 18.061, p=.006) were significantly
associated with participants’ report of lower back discomfort. The larger the discrepancies in the
eye distance (32.1% versus 18.5%), the elbow distance (57%, >6cm versus 32%) and illumination
(67.8%, below 600 LUX versus 31.2%) were, the higher was the proportion of participants
reporting lower back discomfort was. The eye distance discrepancy (=-.401, p=.010; 6.5% of
total variance) and eye level discrepancy (=-.550, p=.001; 9.9% of total variance) were identified
as significant predictors of lower back discomfort.
Wrist Discomfort vs. Work Desk Dimensions
Significant associations were identified between the eye level discrepancy (Chi-Sq(df=5):
32.160, p<0.001), illumination (Chi-Sq(df=6): 24.102, p=.001), and the discomforts in the wrist.
The results showed that the larger the discrepancy in eye level was, e.g. >11cm, the higher the
proportion of participants reported wrist discomfort (89.7% versus 11.3%) was. Besides, the
larger the illumination discrepancy (48.3% versus 17.8%, less than 500 LUX; or 37.9% versus
17.8%, larger than 1000 LUX) was, the more the proportion of participants reported wrist
discomfort was. Among all the abovementioned factors, the eye level discrepancy (=-.414,
p=.013; 6.0% of total variance) was found significantly predicting participants’ wrist discomfort.
Hand Discomfort vs. Work Desk Dimensions
Significant association was identified between the elbow discrepancy (Chi-Sq(df=3):
10.563, p=.014) and the discomforts in the hand (52.1% versus 17.8%). The same variable was
found to be the only significant predictor of hand discomforts.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
STAGE 2B (PART 2): TELEPHONE/ ONLINE SURVEY ON UTILIZATION OF NOTEBOOK
COMPUTER
1.
Method
The Telephone/ Online Survey was a supplement to the Field Survey. The purpose was to
further build up the data base of using different methods. The intention of this part of the study
therefore was not to gain new insights into the situation at hand but to improve the
generalizability of the results. Data was collected through Telephone/ Online Survey.
Questions for the potential participants to complete were extracted from the three
instruments previously used in the Field Survey. The questions covered worker’s demographic,
notebook computer utilization, and physical symptoms. There were two groups of potential
participants: one group was recruited via phone calls and the other group was recruited via e-mail
contacts. Both methods took the subjects about five minutes to complete the survey. For those
who were contacted via e-mails, a direct internet hyperlink accessing to the online survey
webpage was contained in the e-mail.
2.
Results
Demographic Characteristics of the Participants
There were 200 participants completed the telephone (n=18) and online (n=182) surveys.
Among them, there were more female (60.0%) than male (40.0%), which were similar to the
results obtained in the Field Survey (Table 26). About 82.5% of them were between 25 and 39
years old. They mostly carried job titles of legal executive, merchandiser, sales, health
professionals and educator. The participants were from: (1) Community and social servicing
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
(n=70, 35%), (2) Banking, financial, insurance, real estate and commercial servicing (n=45,
22.5%) and Manufacturing industry (n=45, 22.5%), (3) Import and Export (n=20, 10%), (4)
Logistic, storage and communication (n=15, 7.5%), and, (5) Hospitality (n=5, 2.5%).
Table 26 Demographic Details of Participants
(N=200)
Gender
Male
Female
Age (Yr)
20-24
25-29
30-34
35-39
40-44
45-49
50-54
Education
Tertiary
Secondary
Primary/No formal Education
Living (District)
Hong Kong Island
Kowloon
New Territories
%
40.0
60.0
10.0
45.0
35.0
2.5
5.0
0.0
2.5
(N=200)
Occupation/ Industry
Community, Social and
Personal Services
Banking & Finance,
Insurance, Real Estate &
Business Services
Manufacturing
Import & Export
Logistic, Storage and
Communication
Hospitality
%
35.0
22.5
22.5
10.0
7.5
2.5
90.0
5.0
5.0
22.5
30.0
47.5
Notebook Utilization Pattern of Participants
Most of the participants (n=185, 92.5%) reported that they had used notebook computers
for more than two years in their daily works. According to the definition stipulated by the local
Occupational Safety Health (Display Screen Equipment) Regulation, only 7.5% of the participants
might not be considered as DSE users whilst the remaining ones (n=185, 92.5%) might be
regarded as DSE users with their daily utilization of notebook computers were either at least four
hours continuously or more than 6 hours accumulatively (Table 27).
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 27 Years and Hours of Notebook Utilization
(N=200)
Year(s) of Utilization
1 – 1.9
>2
Daily Utilization (Hour)
2 – 3.9
4 -5.9
6- 7.9
>8
%
7.5
92.5
7.5
20.0
37.5
35.0
Different from the results obtained from Field Survey, only 30% (n=60) of the participants
reported using computers outside of offices. Among them, 37.5% used the computers at home,
7.5% at office of clients, and 12.5% at restaurant or other outdoor premises. There were another
7.5 % using notebook computer on the street or public transport (Table 28).
Table 28 Locations of Notebook Utilization of Participants
(N=200)
Necessity for Outdoor Use
No
Yes
Locations of Utilization
Office
Home
Office of Clients
Other Outdoor Premises
On Street
On Transport
%
70.0
30.0
97.5
37.5
7.5
12.5
2.5
5.0
When being asked why the participants were required to use notebook computers at work,
the majority (40%) opined that it was because of their company’s decision of purchase, whilst less
than one-third of them (27.5%) used notebook computers because they fitted the requirements for
outdoor utilization (Table 29). When the participants were asked to make a free choice of the
type of computers to use at work, interestingly, opposite result was shown when comparing with
those of the Field Survey, i.e. there were more participants choosing desktop (i.e. 65%) instead of
notebook computers (i.e. 35%).
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Table 29 Preferences of Types of Computers of Participants
(N=200)
Preference
Company Decision
Need for Outdoor Use
PC Performance
Price
Purpose of PC
Brand
Desktop Space
No Consideration
PC Appearance
Potential Harm
Ergonomic & OSH
Trend
Reselection of PC Type
Notebook
Desktop
%
40.0
27.5
27.5
45.0
22.5
25.0
30.0
10.0
10.0
0.0
0.0
0.0
35.0
65.0
When the participants were asked about the functions utilized, 85% reported using the
computer for word processing, 72.5% for emailing, 65% for Internet browsing, and 60% for
information search. These results were similar to those revealed from the Field Survey (Table 30),
except there were more participants from the Telephone/Online Survey using notebook computer
for Internet Browsing comparing to those obtained from the Field Survey (35%).
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Table 30 Utilization of Computer Functions by Participants
(N=200)
% (from
Tel/Online
Survey)
% (from
Field Survey)
65.0
85.0
7.5
32.5
20.0
60.0
72.5
10
35.0
74.0
2.0
33.0
33.0
52.0
54.5
0
Functions
Internet Browsing
Word Processing
Graphic & Animation
Data Entry
Presentation
Information Search
Emailing
Game
Use of Peripheral Device and other Ergonomics Accessories
The results from the Field and Telephone/ Online Survey indicated that external mouse
and external storage were used together with the notebook computer (Table 31). When the
participants were asked how they carried the notebook for work outside the office, 25% of them
carried it with a handbag, 7.5% with backpack, 10% hand-held the machine, whilst 10% carried it
with a single-side bag. None of the participants used ergonomic accessories such as hand trolley.
Table 31 Summary of Use of Ergonomics Features / Accessories by Participants
Types of Ergonomics Devices / Accessories
Mouse (External)
Storage (External)
Keyboard (External)
Monitor (External)
Printer
Adj Dock
OSH Products
Writing Pad
Occupational Safety and Health Council
% (from
Tel/Online Survey)
% (from Field
40.0
40.0
2.5
2.5
32.5
0.0
2.5
0
92.0
45.0
40.0
26.0
25.0
15.0
13.0
7
Survey)
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Notebook-related Health Characteristics
The most common discomforts expressed by the participants was discomfort in the
shoulders and neck region (80%) (Table 32). Other areas of discomforts included the eyes
(52.5%), the wrist (50.0%), and the lower back and upper back (both are 17.5%). The
participants perceived that the causes of the bodily comfort could be due to work (40%), lack of
rest (25%), and natural degeneration because of aging (5%).
Table 32 Bodily Discomforts Reported by Participants
Locations of
Discomfort
Shoulders and Neck
Eyes
Wrist
Upper Back
Lower Back
Headache
Hand
Lower Limb
3.
%
(from Tel/Online Survey)
80.0
52.5
50.0
17.5
17.5
7.5
5.0
5.0
%
(from Field Survey)
77.0
50.0
29.0
22.0
28.0
3.0
15.0
3.0
Discussion
The results of this part of the study suggested significant relationships between gender and
age, and the duration and functions of utilization of notebook computers by the participants. The
data suggested that notebook computers are commonly used for functions similar to those using
in desktop computers in the workplace. The duration of the participants using the notebook
computers was relatively long such as longer than accumulatively six hours per day. In this case,
the participants might be classified as the “Users” under the existing Occupational Safety and
Health (Display Screen Equipment) Regulation. Significant associations were revealed between
the duration of notebook utilization and the origins of discomforts reported by the participants in
the shoulders/neck, lower back and hand. This further indicated the potential problems brought
by using notebook computers for prolonged period of time. The fact that notebook computers
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were designed for mobile and short duration use which was quite different from that of desktop
computer, i.e. designed for stationary and prolonged duration use. This difference in usage
should be highlighted to both users and employers. The discrepancies between the design of the
notebook computers and their actual pattern of utilization by the participants were less desirable.
The mismatches between the design and the use possibly attributed to the high frequency of
reporting discomforts in the body parts such as the eyes, shoulders/neck, upper limb and wrists.
More importantly, as reflected from findings of this study, the eye-, elbow- and illumination levels
which the participants displayed did not commensurate with the common practices recommended
in the health guides published by the Labour Department (i.e. Simple Guide to Health Risk
Assessment, Office Environment Series – Lighting, 2003; Simple Guide to Health Risk
Assessment, Office Environment Series –
Office Workstation Design, 2003) and the
Occupational Safety and Health Council (i.e. Safety and Health Guides for Working with DSE,
2004).
Previous studies have reported the close relationships between mismatches in these
parameters and work-related disorders (e.g. Blehm et al., 2005, Jaschinski, 1999, Villanueva,
Jonai & Saito, 1998; Saito et al., 1997; Ankrum, 1996).
This study also revealed similar patterns of larger discrepancies associated with higher
proportion of participants reporting discomforts in various parts of the body. The results revealed
further indicated the needs to develop recommendations and best practices for notebook
computer users in Hong Kong.
In general, there were more female than male participants reporting using notebook
computers in both the Field and Telephone/ Online Surveys (63% versus 37% and 60% versus
40% respectively). There was also larger proportion of female participants reporting discomforts
in their body parts. Besides, young to middle age participants (i.e. 30-39 years) were found to
have the highest proportion among other age groups using notebook computers and at the same
time reporting musculoskeletal discomforts over the eyes, shoulders/neck and upper back. Further
studies therefore need to be conducted for explaining the phenomenon of female and 30-39 years
of age participants getting a higher tendency to use notebook computers at work. Nevertheless, it
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was obvious that the tendency of use was associated with the rate of reporting musculoskeletal
discomforts. This again called for development of recommendations and best practices of using
notebook computers in particular to address the needs of this group of users.
Duration and function of utilizations were significantly associated with reports in
musculoskeletal discomforts in the participants. The results suggested that the longer the hours of
notebook utilization was, the higher the incidence of reporting shoulders/neck discomforts would
be. These findings were consistent with those revealed in Leung et al. (2004) of which the results
were obtained from using desktop computers. It was therefore important to incorporate rest
breaks and regular exercise, and reinforce appropriate working posture in the recommendations
and best practices to be developed in this report. To further tackle the issues on prolonged use of
notebook computer at work, it was recommended that the provisions stipulated in the
Occupational Safety and Health (Display Screen Equipment) Regulation should be further
emphasized in the recommendations. As utilization patterns had not shown to associate with the
type of industry, the needs on developing separate sets of recommendations and best practices for
addressing industry-specific issues may not be necessary.
It was noteworthy that notebook computers were reported to be equally utilized both
inside and out of the office. Among the participants who reported using notebook computers out
of the office (about two-third of the participants), over half of them (65%) reported that they
were required to bring the computers back to their homes and use them in the Field Survey. This
perhaps accounted for the prolonged hours of utilization, i.e. accumulatively longer than 6 hours
per day. At the same time, as discussed in the previous paragraph, excessive use of notebook
computers were found to relate to higher incidence of reporting musculoskeletal discomforts in
the shoulders/neck, and upper and lower back. These findings had two implications. First, there
are needs for developing a separate set of recommendations for using notebook computers both
for inside and out of the office locations. The recommendations for using notebook computers
inside the office can be applicable to the use at home. Second, as notebook computers are likely
to be carried in- and out-offices, the recommendations to be developed will incorporate a manual
material handling component.
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The results of the anthropometric measurements from the Field Survey revealed
substantial worker-workstation mis-matches among the participants. The findings suggested that
musculoskeletal discomforts as reported by the participants were associated with the extent of the
deviations from the “appropriate” monitor and desk heights, eye distance and illuminations.
In particularly, these mis-matches were found to associate with the discomforts in the
shoulders/neck, wrist and lower back.
Our findings were consistent with other studies on
occupational health issues brought by using desktop computers (e.g. Villanueva, et al., 1996;
Turville, et al., 1998; Burgess-Limerick, et al., 1999). These mis-matches had been known to
cause excessive strains on the neck, shoulders and upper limb in particular with the higher/lower
monitor height than the eye-level. A closer look at the data revealed that the discrepancies mostly
due to the chairs used by the participants were not adjustable (such as a chair in the restaurant or
conference site) and the height of the desks on which the notebook computers placed were usually
too high. The average elbow-keyboard height mismatch was about 6cm. With this discrepancy,
the participants needed to either raise the chair by 6cm or lower the work surface by the same
height. Besides the elbow-keyboard height mis-match, another common problem was the mismatch between the eye-monitor heights. In general, the mis-match was found to be around 14cm
of which the monitor of the notebook computers was too low for the participants’ eye-level. As
notebook computers do not usually come with an adjustable height monitor, it would be difficult
for aligning the heights between the eyes and the monitor, and the heights between the elbow and
the keyboard with the same desktop surface. This kind of work environment is highly undesirable
for notebook computer utilization. The situation is detrimental when notebook computers are
used as if desktop computers. The illustration of using different workstation designs and /or
accessories will be incorporated in the new recommendations and best practices.
Last but not least, the results obtained from the Telephone/ Online Survey were found to
by and large consistent with those from the Field Survey. This further suggests that the data
obtained in the Stage 2 study is largely valid.
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STAGE 3: RECOMMENDATIONS AND DEVELOPMENT OF HANDBOOK OF GOOD PRACTICES
1. Introduction
In this section, the research process with which recommendations and potential preventive
measures to be considered by the Occupational Safety and Health Council or the employers of the
companies with workers using notebook computers will be described. Development of
recommendations and good practices will be based on the existing utilization patterns gathered in
the previous two stages and the potential threats to occupational health of the workers. No
attempt however will be put on investigating the effectiveness of different strategies for enhancing
workers’ occupational health and use of notebook computers.
2. Methods
The research team adopted a qualitative and participative method to collect feedbacks
from different panels on the recommendations and preventive measures derived from the results
obtained in Stage 2. There were two panels. The first panel was composed of experts in
occupational safety and health, and employers’ representatives (called the expert panel). This
panel was responsible for generating options for good practices, and at the same time explored
their feasibility, compliance and effectiveness.
The experts were those with experiences in
ergonomics, occupational health, occupational medicine, physiotherapy and occupational therapy,
optometry, engineering and representatives of various occupational groups. The second panel
was composed of workers in different occupational groups (called the worker panel). These
workers were those who were recruited and participated in Stage 2 – Field Survey. Their consents
were obtained prior to the participation in this part of the study.
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The results obtained in the Stages 2a and 2b, and the existing Occupational Safety and
Health Regulation on Manual Handling Operations and the Occupational Safety and Health
(Display Screen Equipment) Regulation, and the guidelines published by Occupational Safety and
Health Council and Labour Department were referenced to in the panel meetings. The guidelines
and literature published outside of Hong Kong were also reviewed whenever necessary.
All meetings of the expert panel were conducted before the worker panel. Face-to-face
interview with experts (in group or individual) were held at the experts’ convenience (mostly at
the workplace). Guiding questions were asked by the interviewers in the meeting whilst the
experts’ responses were noted and summarized. The meetings lasted between 30 minutes and one
hour. In the meeting, comments made by the experts were gathered and special attention was paid
on those not covered under the existing Occupational Safety and Health (Display Screen
Equipment) Regulation. After completing the meetings with the expert panel, members of the
worker panel were interviewed. Similar to the format set for the expert panel, meetings were held
in a group or individual basis.
The focus of interviewing with the work panel was on the
feasibility of applying the proposed recommendations and good practices to the frontline work.
Besides, members of the worker panel were asked to suggest changes if any on the proposed
recommendations and good practices.
3. Results
Participants’ Characteristics
Altogether, a total of 57 experts and employers’ representatives were contacted to join the
expert panel. They were previously contacted and participated in Stage 1 of this study. The 100
participants who had involved in the Stage 2b – Field Survey and the 200 participants who had
participated in the Telephone/ Online Survey were contacted for joining the worker panel.
Besides, those potential participants who had been previously invited for participation in this
study but not successful were contacted for the second time. This was believed to further expand
the sample pool in this part of the study.
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A total of 33 participants were recruited for the expert panel and completed the interview.
They came from very diverse backgrounds including information and computing technology,
ergonomics, occupational health and safety, occupational medicine specialists, orthopedic and
traumatology specialist, optometry occupational therapy, physiotherapy and prosthetics and
orthotics.
The final sample of participants in the worker group were from the participants
involved in stages 2a and 2b, and some had not involve in any stage, and 82 participants were
interviewed. Most of them (85%) were those who had involved in the Field Survey and the
Telephone/ Online Survey. They were the workers from the finance, insurance, real estate and
business services, social, community and personal services, logistic, storage and communication
services, constructions, and import and export industries, and some were self-employed (2%). In
total, the 82 interviews conducted reached a saturation, i.e. no new or additional information or
opinions were given by the new interviewees, and the interview henceforth was terminated.
Classification of Utilization Patterns
In general, the utilization of notebook computers was classified into two main patterns.
These patterns were differed in terms of the locations, the purposes and the duration of utilization
of the notebook computer. It was important to note that the patterns proposed in here were to
facilitate the discussion of the issues related to the utilization of notebook computers by the
participants and drafting the recommendations of good practices. There were other patterns of
utilization which were less common than these two but were observed in the field assessment.
Pattern 1 – Notebook Computers Used Outside Office
Users of Pattern 1 can be regarded as conventional notebook computer users. The
notebook computer is used mainly, and in the majority of the cases exclusively, for out-of-office
use.
The purposes of using the computer are for presentations and/or emailing etc. The
locations of utilization are mobile such as in clients’ office or even out of the country. The
duration of use is mostly short such as less than four hours. Because of its mobility, the users
are likely to require carrying the computer and traveling from one place to another.
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Pattern 2 – Notebook Computers Used Inside Office
Users belonging to utilization Pattern 2 are those who use notebook computer mainly
inside the office and/or occasionally outside the office. The purposes of using the notebook
computer are more diverse than those of Pattern 1. They include word processing, internet
browsing, information searching, and/or data entry.
The users are likely to use computer
continuously for four hours or accumulatively for more than six hours. These users may have
their own workstation in their office. Majority of the utilization pattern henceforth is consistent
with the definition of DSE User described under the Occupational Safety Health (Display Screen
Equipment) Regulation, i.e. DSE “User” is defined as an employee who, by reason of the nature
of his work, is required to use display screen equipment for a prolonged period of time almost
every day, (a) continuously for at least 4 hours during a day; or (b) cumulatively for at least 6
hours during a day. Break not exceeding 10 minutes in an hour away from the DSE shall not be
regarded as breaking the continuity of use of the DSE (Occupational Safety and Health (Display
Screen Equipment) Regulation, 2003 and The Code of Practice for Working with DSE, 2003).
Members of both the expert and worker panels were asked to offer their comments and
feedback on the good practices based on the Regulations, hardware enhancement, notebook
computer design, training, and other. A summary of the results of the panel discussions is
presented in Table 33.
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Table 33 Summary of comments and opinions from the Expert and Worker Panel
Collation of Comments from Expert and Worker Panels
Legislation-related
 Application of existing Regulation on MHO to the carrying of notebook computers
 Current Regulation on MHO is applicable to handling of notebook computers
 Apply the spirit of the principles under the Regulation on MHO
 Encourage regular break when carrying the machine
 Encourage to reduce the distance of traveling whenever carrying of the machine is
needed
 Encourage to use proper manual handling techniques
 Encourage to reduce the weight of the machine and its accessories
 Application of existing Occupational Safety and Health (Display Screen Equipment) Regulation
 Current Occupational Safety and Health (Display Screen Equipment) Regulation is
applicable to the use of notebook computers including the definitions set for
identification of a user
 Conduct risk assessment for users who meet the definitions set for a “DSE User” or,
 Conduct risk assessment for all notebook computer users disregard their “User” status
 Provide adequate DSE training for all notebook computer users
 Apply the spirit of the Occupational Safety and Health (Display Screen Equipment)
Regulation
 Encourage users to take regular break
 Encourage users to do regular stretching
 Adopt proper ergonomic design and layout for the workstation on which the
notebook computer is placed
Enhancement of Notebook Computer
 Add appropriate external accessories for prolonged use in word processing or Internet browsing
 Connect external monitor to computer for extending the height of the monitor screen (for
better monitor to user’s eye-level match)
 Use dock or stand for extending the height of computer screen (for better monitor to
user’s eye-level match)
 Connect external input devices, e.g. keyboard and mouse to computer (for better
keyboard/mouse to user’s elbow-level match)
 Use of wrist and/or mouse pad
 Use height adjustable swivel chair (for better seating to workstation height)
 Provide ergonomic carrying bag for taking notebook computer out of the office
 Use backpack for carrying the computer and its accessories
 Use single-side shoulder carrying bag for short distance and lightweight machine
 Use hand trolley for transporting the computer and its accessories for long distance and
heavyweight machine
 Use alternate hands to hand-carry the bag in which the machine and its accessories are
kept
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








Improvement of Hardware Design
Enhanced ergonomic features
 Design of monitor screen
 Larger but lighter screen
 Size of the screen in proportion to working distance, font size etc
 Detachable screen
 Height adjustable screen
 Light weight design
 Reduce overall weight of the machine
 Reduce weight of the transformer and battery
 Reduce weight of the carrying bag
 Reduce weight of the external devices, e.g. CD/DVD ROM
 Design of keyboard and mouse
 Replace fix with detachable or external keyboard
 Use flip-out keyboard (to widen the keyboard space)
 Use tiltable keyboard to accommodate users who prefer working with a slightly
extended wrist position
 Build in wrist resting space proximal to the lower edge of the keyboard
 Replace touch pad mouse by external mouse
 Other design feature
 Increase the capacity and durability of the battery
Training
Equip users with knowledge on the design and set up of the workstation with reference to
sound ergonomics principles
Learn proper carrying methods
Learn to do stretching exercises on a regular basis
Others
Learn the reasons behind using a notebook computer (for better portability, and out of office
and/or short duration utilization)
Encourage to use desktop computer in an office environment
Encourage to use alternate technology to replace notebook computer
 Use lighter and smaller handheld device, e.g. PocketPC, BlackBerry
 Use external storage device for carrying data or files, e.g. USB or external hard drive
 Use remote or network technology for download data or work tasks via intranet or
Internet
Set alternate rest and machine using time (e.g. 50 minute followed by 10 minute break)
Set restrictions for using notebook computer
 Avoid prolonged typing
 Avoid prolonged browsing
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4. Proposed Recommendations and Good Practices for Utilization
Non DSE users Mainly with Out-of-office Utilization
This type of users is in general those under utilization Pattern 1. The users are required to
use notebook computer for out-of-office work. The spirit of the MHO principles under the
Regulation on MHO is for the employers to take appropriate and practical steps on reducing the
risks associated with lifting and carrying a weight during work. This would call for the employers
to provide appropriate mechanical aids and/or protective equipment when the users are required
to carry a notebook computer (and its accessories) outside the office. It is advisable that users
can be provided with proper type of carrying bag or device such as hand trolley. A few of the
examples are listed in Table 34.
Table 34 Comparison of Different Computer Bag Designs
Types
1. Backpack
Ergonomic Features
Comments on Usefulness
 Left and right
 Convenient and hand free
straps distributing
 Suitable for long distance
loads onto both
and prolonged duration
shoulders
carrying
 Enable good
 Space good for notebook
carrying posture in
computer and its peripheral
the back
accessories
 Light in weight
 Adequate space for
loading
Appearance
 Less
attractive for
users in
business and
in formal
meetings
2. Hand Trolley
 Less loading on
users shoulders
 Pulling with one
hand or alternate
hands, and traction
force in shoulders
and elbow
 Heavy in weight
 Less
attractive for
users in
business and
in formal
meetings
Occupational Safety and Health Council
 Space good for notebook
computer and its peripheral
accessories
 Lifting of hand trolley and
its content when climbing
stairs and crossing curb
 Excessive pulling of the
trolley may lead to upper
limb musculoskeletal
disorders
 Only suitable for long
distance and duration
carrying
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Types
3. Single-side/
Messenger Bag
4. Hand Carrying
Ergonomic Features Comments on Usefulness
 Only one strap
 Exert relatively heavy
putting load on
load on one shoulder
either the left or
 May lead to improper
right shoulder
posture on the shoulder
 Light in weight
and the back for
 Adequate space
compensating the
primarily for
uneven distribution of
notebook computer
load
 Suitable for short
distance and duration
carrying
 Less space for carrying
other accessories
 One hand or
 The most convenient for
alternate hands to
carrying
carry the notebook  Suitable for short
computer
distance and brief
 May use a soft
traveling within the city
sponge bag for
 Only good for carrying a
holding the
lift weight and slim
computer
notebook computer
 May exert excessive
load onto the hand
Appearance
 Slim and
smart looking
 Conventional
to users in
business and
attending
formal
meetings
 Acceptable by
most of the
users
Among the four carrying methods, the panel members opined that the “backpack” was the
most desirable in terms of enhancing the occupational safety and health of users who belong to the
Pattern 1 as defined in this study. This method was regarded as the most useful when users are
required for carrying the notebook computer for use out of the office. The “backpack” was
commented as offering the most ergonomic features and the best for preventing discomforts and
perhaps work-related disorders among the users. In contrast, the “hand trolley” was regarded as
less desirable but was useful if users are required to carry notebook computer of heavier in weight,
larger in size, more peripheral accessories, and/or carrying for long distance travel. This was
deemed to be quite common in particular when notebook computers are used for sale
demonstrations and exhibitions.
The panel members also remarked that the “single-side/
messenger bag” could be useful because of its convenience if users are required to carry a light
weight notebook computer for short distance daily work travel.
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Besides the carrying bag (or method), the following manual handling recommendations are
deemed to be appropriate for further enhancing the occupational health and safety of users
belonging to the Pattern 1 (carrying notebook computer for out-of-office use):
 Keep the load close to the body, i.e. centre of gravity, and back straight
 Swap hand if hand carrying is preferred
 Reduce weight and amount of load to be carried
 Use appropriate aid to minimize weight of load
 Take regular break during carrying
 Reduce carrying distance and duration as appropriate
It is important to note that users with their utilization pattern similar to those described
under Pattern 1 are less likely to be defined as “DSE users” under the existing Occupational
Safety and Health (Display Screen Equipment) Regulation. Nevertheless, it would be desirable
for the users and their employers to if possible apply the following principles at work:
 Screen is to be positioned in front of the user
 First line on screen is as much as possible to be aligned to the about or just below eye
level (notebook computer to be placed at a higher than desktop level)
 Screen is to be located at a comfortable viewing distance at 350 - 600 mm, (for instance,
14-inch wide screen corresponds to about 400mm)
 Screen is easily tilted to suit the needs of the user
 Move computer monitor away from windows or other sources of bright light
 Avoid positioning monitors parallel to windows
 Screen should give a clear, sharp and steady image
 Characters should be of adequate size, with adequate spacing between the characters and
the lines
 Brightness and contrast of the image should be easily adjusted
 Adjust the contrast and brightness levels on your monitor to find the setting that gives
you the best clarity
 Use wrist or mouse pad
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When taking the notebook computer out of the office, it is recommendable for the users
and their employers to consider using (or providing) an external mouse to replace the built-in
touch pad mouse. This will enable the users to operate the pointer function more easily and
ergonomically. An external keyboard can also be considered if users are required to use notebook
computer for tying texts. The consequence of adding these external devices is the increase in the
weight when carrying the notebook computer. The panel members opined that the manufacturers
of notebook computers could further consider options for adding built-in devices, and reduce the
overall size and weight of the computer in the future. Below is a list of the features for the
manufacturers’ consideration:
 Larger but lighter monitor
 Height adjustable monitor
 Reduce weight of battery and electric supply gadget including the transformer
 Improve the life of the built-in battery so that users do not need to carry the transformer
together with the computer
 Expandable and/or tiltable keyboard to minimize stress on wrist and finger joints
 Built-in external mouse
One important point raised by the panel members was on the necessity of using a notebook
computer. The panel members pointed out that it would be the responsibility for the employers
(or supervisors) to justify the needs for purchasing notebook computers for the use of their
employees. Justifications would be needed for employees to bring notebook computer for use out
of the office. Other technologies should be considered before deciding on the use of notebook
computer. Finally, when a notebook computer is used, the employers and supervisors should be
mindful of providing adequate training to the employees on its proper use. The content of such
training may include carrying and lifting technique, ergonomic principles of using DSE, and
stretching exercises.
A decision tree (Figure 2) was constructed to facilitate employers or
supervisors making proper decisions on purchase and provision of proper carrying tools for
employees who are prescribed with notebook computers. The decisions are made according to the
rules and recommendations suggested by the experts, who were interviewed in this phase of study.
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These experts composed of experts with background and experiences in ergonomic, occupational
safety and health, medical and healthcare, and employers as well as users.
Performing computer work
outside of office
Figure 2
Are there other options available?
Yes
For example
Content can be stored with an external storage/
server/ over the Internet and downloaded to
designated computer
Or
Other handheld devices such as PDA
Notebook
Computer is not
needed
No
No
Notebook Computer
is
needed
How much weight is to
carry including document
and peripheral
accessories?
Light
Heavy
What is duration
of the carrying?
What is duration
of the carrying?
Long distance or
overseas
Overseas
Hand Trolley
Short Distance
Long distance
Back Pack
Short Distance
Computer Bag
Very brief duration
Carry with Hand
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Performing computer work
exclusively inside an office
Figure 2
Yes
Is desktop computer available
in the office?
No
Notebook Computer
is not
recommended
No
Do you have to use a notebook
computer at different locations
Yes
No
Are these accessories available
for use?
An external monitor, keyboard &
mouse, or
A notebook stand, external
keyboard & mouse
Yes
No
Have you received OSH
related training?
Yes
Notebook can be used
DSE User Mainly with Indoor Utilization
Users are those who intensively use notebook computer in their day to day work.
According to their duration of using a computer, they are regarded as “the DSE Users.” They
primarily use notebook computers in their offices but may need to occasionally bring the
computer for out-of-office use. The panel members suggested that users of this type should
follow the recommendations set mainly for indoor utilization. To cater for out of office utilization,
users are advised to follow the recommendations made for the “Non User Mainly with Outdoor
Utilization”.
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Inside the office, users probably use notebook computer continuously for four hours or
accumulatively for six hours in a work day. They are advised to observe the Code of Practice for
Working with DSE (2003) and the Occupational Safety and Health (Display Screen Equipment)
Regulation. A few of the important recommendations modified for notebook computer users are
suggested below:
1.
Use of External Monitor
It is used for compensating the non-detachable and non-adjustable height of notebook
monitor. In general, when notebook computer is placed on the desktop, the height of the
notebook monitor is rather low to the eye-level. Any mismatch between the monitor height
and user’s eye-level may lead to excessive strains in the neck and shoulders which is not
desirable from an occupational safety and health point of view. Connecting the notebook
computer to an external monitor which is height adjustable could alleviate this problem by
eliminating the differences in the monitor height and user’s eye-level. This set up was
deemed to be crucial by the panel member for the DSE Users. The positioning of the
external monitor can make reference to Figure 3.
Figure 3
A
A
B
B
C
F
F
E
G
H
Occupational Safety and Health Council
D
E
G
H
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
A.
B.
C.
D.
E.
F.
G.
H.
2.
The top edge of the screen is about or just
below the eye level of user
Keep a comfortable eye distance at 350600mm
Use of notebook stand to adjust height
and/or distance of screen of notebook
Use of external keyboard and mouse
Enough space in front of the keyboard to
provide support for the hands
Keep shoulder relaxed and forearm at
about right angle to arm during typing
Keep back straight and rest against
backrest of the seat and hip at about right
angle to trunk
Use height adjustable seat and with armrest
Dock/ Notebook Stand
Instead of connecting the notebook computer to an external monitor, one may consider
housing it into dock or monitor stand (Table 34). This can raise the height of the notebook
monitor to a higher level resulting in a better monitor height to eye-level match.
For a
regular size notebook computer (such as 14-inch wide screen), an external keyboard and
mouse are commonly needed so that the layout of the workstation is ergonomically sound.
The commercially available options in the local market can be found in Table 34.
Table 34 Different notebook stand designs available in the market
Types of Dock/ Monitor Stand
Occupational Safety and Health Council
Advantages
Disadvantages
 Convenient to be
setup on the
desktop
 Not height
adjustable
 Inadequate wrist
space at work
 Excessive tilt
angle at the wrist
 Height of monitor
screen is
adjustable
 Convenient to
setup
 Limited range of
height adjustment
which may not fit
all users
Connect to
external input
devices
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
Types of Dock/ Monitor Stand
3.
Advantages
Disadvantages
 Height of monitor
screen is
adjustable
 Document holder
is available for use
 Limited range of
height adjustment
which may not fit
all users
 Connect to
external input
devices
 Height of monitor
screen is
adjustable
 Flexible
positioning of
notebook
computer
 Inconvenient for
connecting to
external input
devices
External Keyboard and Mouse
In many circumstances, external keyboard and mouse are the crucial set-up of notebook
computers in offices. The following are a few considerations for selecting external keyboard:
 Keyboard should be as thin as possible, tiltable and detachable for accommodating
different work situation and posture of the users
 Keyboard should be neutral in color and non-reflective
 Letters and symbols on the key tops should be clear and easily recognized
 Sufficient space in front of the keyboard to provide support for the hands
Other ergonomic features and principles for DSE Users using desktop computers are also
appropriate for the use of notebook computers. They are the use of document holder, wrist or
mouse rest, adjustable swivel chair, and footrest. Employers should bear the responsibility for
conducting regular DSE risk assessment for users of this type (Table 35). It is also a good
practice for employers to provide adequate occupational safety and health training for optimizing
occupational safety and health in the office.
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Table 35 Notebook computer utilization risk assessment checklist
Section A
Display Screen
1. Is the notebook computer connected with an external screen, or being placed on
a secure docking?
2. Is the screen positioned at about or slightly below the eye level?
3. Is the screen positioned right in front of the user?
4. Does the screen give a clear, sharp and steady image?
5. Are the characters readable?
6. Are the brightness and contract adjustable?
7. If using external screen, does the screen swivel and tilt? If not using external
screen, does the screen tilt?
8. Is the screen free from reflections and glare?
Y
□
N
□
N/A
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
□
Y
□
□
□
□
□
N
□
□
□
□
□
N/A
□
□
□
□
□
Y
□
N
□
N/A
□
□
Y
□
□
□
□
□
N
□
□
□
□
□
N/A
□
□
□
□
□
□
Y
□
□
□
N
□
□
□
N/A
□
Y
□
N
□
N/A
□
Y
□
Y
□
N
□
N
□
N/A
□
N/A
□
Y
□
N
□
N/A
□
Section B
Input Devices
9.
10.
11.
12.
13.
Are external mouse and tiltable keyboard used?
Are the characters on the keys of the keyboard readable?
Is the keyboard glare free?
Are the input devices positioned at about the elbow level?
Is there enough space to rest hands in front of the input devices?
Section C
Work Desk
14. Is the desk surface large enough for the notebook computer, docking/external
screen, external keyboard, external mouse and documents?
15. Is there adequate leg-room below the desk?
Chair
16.
17.
18.
19.
Is the base of the chair stable?
Do the casters allow easy movement of the chair?
Is the seat height adjustable to suit the body size of the user?
Is the backrest adjustable in both height and tilt to provide adequate support to
the lower back?
20. Is the seat pan padded and free from sharp edges?
21. Do the armrests, if any, allow the user to get close enough to key comfortably?
Document Holder
22. Us the document holder, if provided, properly positioned to avoid awkward neck
posture and movement?
Footrest
23. Is the footrest, if provided, stable and provided with a non-slip surface?
Illumination
24. Is the lighting level suitable for the work?
Noise
25. Is the noise produced by the workstation acceptable?
Section D
Carrying
26. If need to carry the notebook computer, is appropriate carrying method used?
.
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PROJECT CONCLUSION
This consultancy project was conducted between October 2007 and February 2009 taking
a total of 15 months. There were three stages in the study which provide the necessary data and
evidence which are useful for the Occupational Safety and Health Council and probably other
agencies to develop recommendations and good practices for employers and employees when
using notebook computers in the workplace.
Stage 1 of this study involved interviews of experts in the field of occupational safety and
health. The aim was to gain better understanding on the utilization of notebook computers in
Hong Kong and the problems, if any, associated with the use of the computers. In general, the
findings indicated that no particular industry or user group predominantly used or not used
notebook computers, or used notebook instead of desktop computers. The comments gathered
from the panel also revealed that the users tended to use notebook computers to replace the
functions used to be covered by desktop computers. As a result, notebook computers were
commonly used for typing- and browsing-related tasks. Conventional functions such as displaying
the presentation materials and emailing were no longer the sole reasons for using notebook
computers. The decision of purchasing or selecting notebook computers was not merely to
satisfy the needs for out of office use. More often, however, their use was to accommodate the
limited workspace in small offices, and the purchase polices or strategies of companies.
Stage 2 of this study was a Telephone Survey on utilization, preference and health-related
issues associated with notebook computers. The Survey covered adult workers and at the same
time school-age children. As this study put a focus on adult workers, the results obtained for the
school-age children were not elaborated in this report. The results revealed that there was
relatively small proportion (about 10%) of the workers’ population using notebook computers
(when compared with desktop computers).
Notebook computers were in general used for
multiple functions with majority of them was typing-related such as word processing and
browsing the Internet. The typing-related tasks were mostly prolonged in duration such as six
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
hours or longer in a day. This perhaps explained the results that relatively large proportion of the
participants was found to experience musculoskeletal discomforts in the eyes, wrist,
shoulders/neck and lower back. Prolonged duration of utilization and typing-related tasks were
found to relate to the larger proportion of the participants experiencing discomforts over the
shoulders/neck and lower back. The use of external devices such as external monitor and mouse
added to notebook computers revealed a smaller proportion of the participants reporting
discomforts in the bodily parts.
The anthropometric measurements conducted to the participants gathered further evidence
on the associations between the better worker-workstation match and the lower chances of the
participants experiencing musculoskeletal discomforts. It is noteworthy that the findings revealed
from this part of the study largely concur with those obtained from other parts of this study. The
results revealed that most of the notebook computer participants assumed a rather inappropriate
working posture when compared with those stipulated in the common practices recommended in
different health guides published by the Labour Department (i.e. Simple Guide to Health Risk
Assessment, Office Environment Series – Office Workstation Design, 2003; A Health Guide on
Working with Display Screen Equipment, 2002) and the Occupational Safety and Health Council
(i.e. Safety and Health Guides for Working with DSE, 2004) The extent of the mismatch between
the proper and actual posture was found to have significant association with the chance of the
participants experiencing musculoskeletal discomforts.
The use of external devices by the
participants was associated with a smaller proportion of the participants experiencing the
discomforts. The use of external devices was also found to effectively reduce the discrepancy of
the worker-workstation mis-matches.
Last but not least, the materials on different ways for enhancing occupational safety and
health practices among notebook computer users were developed in this report. Good practices
were recommended based on the results obtained from Stages 1 and 2, together with the existing
relevant legal requirements. The materials would be useful to the Occupational Safety and Health
Council for developing recommendations for alleviating the potential risks associated with using
notebook computers. These recommendations can be used by workers who are using notebook
computers or those who have plans to incorporate notebook computers in their workplace.
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Final Report on Use of Notebook Computers and Related Ergonomics and Occupational Safety and Health Problems
The research team considered the spirit of the existing legal requirements on manual
handling operation and display screen equipment would be relevant to be applied to notebook
computer users, especially, those who need carrying notebook computer for use outside the office
and prolonged utilization in a workday. The notebook computer users were reminded to beware
proper manual handling operation principles and techniques, for instance, reducing carrying
weight, duration and distance, and encourage regular break during carrying. Besides, they will be
encourage using ergonomics gadgets e.g. backpack or hand trolley. Apart from proper carrying
considerations, notebook computer users are also recommended to make reference to the
Occupational Safety and Health (Display Screen Equipment) Regulation, principles and
techniques using notebook computer so as to achieve a match between their anthropometric
dimensions and the workstation. As a result of the relatively low monitor height of notebook
computer, the research team recommended using ergonomic external accessories when prolonged
typing or browsing with the notebook computer is needed, e.g. external monitor/ notebook stand,
external keyboard and mouse. The employers of the notebook computer users are also reminded
to conduct regular DSE risk assessment and provide adequate training for users to enhance better
occupational safety and health using the notebook computers.
Limitations of study
The data collected In Stage 1 – expert interview used a qualitative approach. The
participants were recruited with convenient sample method, whilst these participants might not
necessarily represent all the industries in Hong Kong. The results obtained from the data therefore
cannot be generalized to the industries not represented by the participants. It is important to also
note that the qualitative approach adopted in Stage 1 was aimed to facilitate the research team to
understand the practices and issues related to use of notebook computer, the research team did
not attempt to base on the results to formulate conclusions on the issues or recommendations for
good practices.
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As mentioned in the previous section, the sample size of the participants of the telephone
survey conducted In Stage 2a was deemed adequate. The results generated at the group level, i.e.
working adult versus school-age children would have a good validity. However, the sample sizes
at the sub-group level such as those who reported using notebook computer or having high level
of discomfort might be inadequate for generating valid results. Readers should be cautious when
interpreting the results at this level. The results also cannot be generalized to the population not
represented by the sub-group samples. Besides, the data obtained from the telephone survey was
based on participants’ self-report, and their subjectivity, despite the chance is rather slim, could
have biased the results. On the contrary, the sample size of the participants involved in the field
assessment conducted in Stage 2b was deemed adequate (results further triangulated by a round
of telephone survey). The findings on the usage pattern of notebook computer, anthropometric
measures, and level of discomfort would have good validity. The results and the conclusions
drawn can be generalized to the populations which the participants represented. Nevertheless,
readers should still be cautious to make sure that the characteristics of the workstations and the
ways which the notebook computers are used are similar to those stipulated in this study before
making the generalization.
The recommendations of the common and good practices suggested in Stage 3 went
through a series of consultations with the stakeholders and the occupational health and safety
experts. The research team believed that the contents should be practical and useful for the
industries. The main drawback is that the recommendations are feature- rather than industry-based,
i.e. functional needs of notebook computer. As a result, the recommendations offer only generic
practices in the needs assessment, design of workstations, and use of accessories and peripheral
devices, readers would need to devise the practices specific to their workplace and job description
needs. Besides, the recommendations cover only the two most common work scenarios, readers
should base on the examples given in the report and develop their own practices for those which
do not fall under these two categories.
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WORK SCHEDULE
Months
1st
2nd
3rd
st
1 Quarter
4th
5th
6th
7th
nd
2 Quarter
8th
9th
10th 11th
3rd Quarter
12th
13th 14th 15th
Final Quarter
Tasks:
Stage 1 Study


Stage 2a Study
Stage 2b Study










Stage 3 Study
Interim Report










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

Final Report and
Guide Book
Presentation 1
Presentation 2
Presentation 3
Presentation 4
WORK PROGRESS SUMMARY:
Task
Task Description
No.
1.
Phase 1 – Expert
Interview
2.
Phase 2 – Telephone
Survey
Phase 2 – Field
Assessment
3
Literature Review and
Expert Interview
Progress
Completed
Schedule
Start Date
Oct 07
Actual Start
Scheduled
Date
Completion Date
Oct 07
Feb 07
Actual
Completion Date
Feb 08
Completed
Dec 07
Nov 07
Feb 08
Jan 08
Completed
Dec 07
Dec 07
July 08
Aug 08
Completed
Sep 08
Sep 08
Nov 08
Jan 09
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