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Ergonomics issues related to children, computers and schools
Susumu Saito
Institute for Science of Labour, Kawasaki, Japan
Rapid introduction of information and communication technology into the school environment was
revealed to have possibilities to create obstacles to health and safety of children. It is necessary to be
paid more attention based on the following ergonomics viewpoints to protect the healthy developments
of children. Using the large display caused constrained working posture, increase in ocular surface area
and shift in binocular vision. Those physiological problems are more serious for those with a small
physique, such as schoolchildren. Using the notebook computer caused visual fatigue and constrained
posture. Before introduction of the notebook computer into schools, practical use of the ergonomics
guidelines is recommended. Ergonomics requirements might be needed for using the complicated
Chinese characters from the ophthalmological viewpoints.
Ergonomics involving children and the educational environments is considered to be a key issue in
ensuring the safety and security of those in our society.
INTRODUCTION
In our society, information and communication technology
(ICT) has been rapidly introduced into schools as well as
offices, factories and homes. Although the International
Ergonomics Association (IEA) has continued lively activities
through its technical committee (TC), Ergonomics for Children
and the Educational Environments (ECEE), many ergonomics
problems related to ICT use by children, such as
musculoskeletal disorders and visual fatigue, remain unsolved.
Nigel Corlett in a forward to a recently published book stated
that “in spite of the large population of children, school (the
workplace of the young) has a relatively small body of
ergonomics studies and the ergonomics of play even less”
(Corlett, 2008). Children are the torchbearers and the creators
of the health and safety of our society. The aim of this paper is
to review the musculoskeletal and ophthalmological aspects of
ICT use in schools and to clarify the ergonomics problems
while children using the ICT tools in educational
environments.
TRENDS OF ERGONOMICS RELATED TO ICT
AND AREAS OF CHILD HEALTH
As early as at the 2nd International Conference on Work
with Display Units, or WWDU’89, in Montreal, Bengt Knave
anticipated serious problems in the use of video display units
(VDU) in schools (Knave, 1989). He summarized many
obstacles in the use of VDU in schools and emphasized the
necessity to solve the various problems related to VDU use
presented to both teachers and children. The ergonomics issue
of "IT in schools" was followed-up at the 5th WWDU'97 in
Tokyo (Knave, 1997).
A symposium entitled “Children, Computers and
Classrooms” was held at the IEA 14th Triennial Congress in
2000. The late Cheryl Bennett, the first chairperson of the
IEA/TC/ECEE, organized and led this symposium to success
(Bennett, 2000). David Caple, the IEA president, contributed a
memorial to his Letter from the President (Caple, 2007). Karen
Jacobs has eagerly taken over the ECEE committee activities
(Jacobs, 2009). The relevant papers and references to this area
are open to the public in the website of ECEE. In the site, the
worldwide studies are summarized in the table, and classified
in the fields of anthropometrics, computer use, computer and
vision, school furniture design, low back issues, etc.
The publication of a voluminous work, Ergonomics for
Children, was an epoch-making event in bringing about an
understanding of the massive body of knowledge on this
subject as is represented by its subtitle, “Designing Products
and Places for Toddlers to Teens” (Lueder and Rice (Eds.),
2008). One chapter in this book is “Information and
Communication Technology in Schools” (Pollock and Straker,
2008).
The Japanese Ministry of Education, Culture, Sports,
Science and Technology (MEXT) announced on its web site
(MEXT, 2008a) that as of March 2008, 56.5% of classrooms in
elementary schools in Japan had visual display terminals (VDT)
equipped with the Local Area Network system (LAN). The
new ICT strategy of the Japanese government includes the aim
that all public school classrooms be equipped with LAN by
March 2011. Developments in science and technology are
double-edged swords that may improve the quality of human
life but that also may create obstacles to health and safety. This
point of view should be a source of concern, and special
requirements are needed in the case of growing children who
are vulnerable to injury and the effects of stress. A proactive
approach must be taken to eliminate foreseeable ergonomics
problems in schools caused by the use of these technologies.
Special ergonomics requirements are needed for growing
children
Japan is one of the countries that uses the complicated Kanji
or Chinese characters and has a keyboard input style for word
processing that differs from that in countries that use the
alphabet. The number of Chinese characters designated for
daily use in Japan, such as in newspapers, official documents,
etc., is 1945. The Japanese government mandates that
elementary schoolchildren should learn 1,006 Chinese
characters. Reading block letters and discriminating those
complicated characters on the electronic display might cause
an excessive workload on the eyes of schoolchildren, which
was reported in our experimental and clinical studies
(Marumoto et al., 1999, 2003). Edwards and Lam reported that
an epidemiological study in Hong Kong showed that the
prevalence of myopia amongst the Chinese had escalated in
recent decades (Edwards and Lam, 2004). They concluded that
the increase in the prevalence of myopia could be postulated to
be due to environmental factors.
Increase in the ratio of myopic children, and international
comparative data on myopia in school-age children. There
is disagreement as to whether myopia or nearsightedness is
caused by genetics or the environment (Fostervold and
Ankrum, 2008). The MEXT annually reports data on growth
and development as well as the health conditions of boys and
girls in schools (MEXT, 2008b). This nationwide survey is
conducted on samples of boys and girls from kindergarten,
elementary school, junior high school and high school. In 2008,
for example, the data were extracted from 1,350,000
elementary schoolchildren in 2,820 schools.
development.
The World Health Organization (WHO) collects and opens
to the public data on refractive error or myopia in school-age
children in some countries (WHO, 2009). The survey on the
refractive errors of school-age children in the different
populations in the same urban district in Malaysia could be
confirmed in the WHO website. Age group examined in this
survey was from 7 to 15 years old. The reported result
concerned with Malaysia is that the prevalence % of myopia in
Chinese population is 45.3 and 95% CI is 39.8-50.8. Contrary
to this, prevalence % of myopia in Indian and Malay
populations in Malaysia is 15.5 and 13.9, respectively.
Additionally, prevalence % of myopia in school-age children
in South China is 35.1 and 95% CI is 33.2-36.9.
Saw et al. found that the prevalence of myopia was higher in
the city than in the countryside among Chinese schoolchildren
and concluded that the increased near-work activity might
have contributed to the prevalence of myopia. (Saw et al.,
2001, 2002). Garner et al. examined data on myopia obtained
from groups of Sherpa and Tibetan children groups in Nepal
(Garner et al., 1999). The prevalence of myopia in Sherpa
children was low and their rural lifestyle appeared to be
relatively unstressed. They indicated that Tibetan children have
a higher prevalence of myopia than Sherpa children and more
rigorous schooling, and that the rural lifestyle is at least
compatible with a virtual absence of myopia.
Musculoskeletal and ophthalmological aspects of ICT use
in schools.
The survey on the elementary schoolchildren
revealed many ergonomics and postural problems. In the
quantitative analysis of young students while studying, a
significant correlation was found between visual and postural
parameters (Marumoto et al., 1999).
Figure 1 Increases in the ratio of myopic children in
Japanese elementary schools (MEXT, 2008b).
Figure 1 shows annual changes in the percentage of myopic
children from 1980 to 2008 as revealed by MEXT surveys. In
this survey, visual acuity is expressed in decimal digits, not in
fraction. It is obvious from the Figure that the ratio of myopic
children has increased year by year. In 2008, about 30% of
elementary school children were myopic with visual acuity
lower than 1.0, and 7.1% of children were myopic with visual
acuity lower than 0.3. According to the MEXT data, the ratio
of myopia increases with increases in the educational level;
53% of junior high school students and 58% of high school
students are myopic with a visual acuity lower than 1.0.
One of the most serious problems caused by inappropriate
use of ICT in schools might be long-term effects on the visual
system, such as myopia in children. Although the relationship
between close work and myopia is still unclear (Mutti et al.,
2002), special attention should be given to ergonomics in the
ICT environments of children from the viewpoint of child
Figure 2 A photo taken in a computer classroom of an
elementary school in Tokyo. Short viewing distance and other
ergonomics problems caused by use of inappropriate desks and
chairs were found by postural analysis of the schoolchildren.
From a postural analysis of 48 schoolchildren during ICT
class, Akutsu at al. identified a number of ergonomics
problems from visual and postural aspects such as too little
distance between the eye and screen, decreased blinking rate,
and the need for desks and chairs that better fit a child’s body
including desks of an appropriate height and chairs with a
footrest and backrest or body-support devices as shown in
Figure 2 (Akutsu et al., 2001).
Based on the quantitative analysis of postural parameters
for schoolchildren while using computers, Akutsu et al.
designed a computer workstation for schoolchildren, including
a desk and chair as a prototype (Akutsu et al., 2001). The desk
and chair was designed so that the child would maintain an
appropriate viewing distance between the screen and eyes and
support for the body would be provided, even for small
children, with an adjustable backrest and footrest. The position
of the footrest is mechanically linked to the position of the
backrest to avoid the necessity for adjustments. This prototype
of a workstation is designed to enable VDT operation with an
adequate posture for 95% of the physiques of elementary
school boys and girls using anthropometric data on the
Japanese body size from ages 6 to 11 years.
Our experimental study revealed a significant correlation
between failing eyesight and postural parameters of young
students while studying (Marumoto et al., 1999). The mean
age of the 19 subjects was 13.2 years, and 9 were classified as
emmetropic and 10 as myopic. Viewing distance, viewing
angle, neck angle, vertical gaze direction, and ocular surface
area while the subject was engaged in study were evaluated.
The mean viewing distance and standard deviation of the
myopic group was 15.0 cm±1.9 cm, which was significantly
shorter than those of the emmetropic group (30.2 cm±4.1 cm).
The shorter viewing distance implied poorer vision and a
larger extent of deterioration of ocular accommodation. Neck
angle, viewing angle, visual acuity, near point, and
accommodative power were correlated with viewing distance
(p<0.01).
The most common visual problems encountered among
young patients in an ophthalmologic clinic were studied with
my colleagues. In this clinical case study, the proposed
mechanisms for the deterioration of the children’s eyesight
associated with the use of ICT tools such as mobile phones and
electronic games are decreased accommodative power,
increased anisometropia or the presence of unequal refractive
error of the eyes, abnormality in convergence, and inadequate
correction of refractive errors (Marumoto et al., 2003).
ERGONOMICS CONSIDERATIONS RELATED TO
ADVANCES IN DISPLAY TECHNOLOGY
Large displays
Large flat panel displays such as 19-inch liquid crystal
display (LCD) monitors are superseding the conventional
cathode ray tube (CRT) for various types of VDT work. The
use of a large display is a welcome development for users
because the larger size itself increases visual comfort by
enlarging the user interface for information display. Especially,
using complicated Kanji or Chinese characters requires an
electronic display with high spatial resolution.
On the other hand, a shorter viewing distance and increased
angle of the upward gaze are inevitably required when large
displays are placed on the top of traditional desks in
comparison with the use of smaller displays. The need to gaze
upward is well known as one of the most undesirable
drawbacks of VDT work from the viewpoint of visual
ergonomics (Taptagaporn and Saito, 1993; Fostervold and
Ankrum, 2008). These disadvantages of using large screens are
more serious for those with a small physique, such as
schoolchildren.
The average vertical eye position of VDT operators was
found to be 7.5 deg upward from the horizontal plane or
Frankfurt plane (Saito et al., 1993a). Contrary to this, visual
tasks performed on a desk without a VDT permit a downward
gaze that was 28.9 deg below the Frankfurt plane. Ergonomics
problems with the use of a large screen that may cause serious
physiological effects are summarized based on our
experimental studies as follows:
Constrained working posture.
The experimental study
by Villanueva et al. (1996, 1997) revealed that neck angle,
thoracic bending and vertical gaze position were significantly
affected by changes in screen height of the VDT. Prolonged
use of a large display was considered to be a major cause of
neck and eye disorders and subjective discomfort among VDT
workers.
Increase in the ocular surface area.
The upper eyelid
and eyeball move together in a physiologically synergic action
during eye movement in the vertical direction (Saito, 1975;
Saito et al., 1978). Consequently, upward gazing increases the
ocular surface area (OSA) in proportion to the vertical eye
positions (Sotoyama et al., 1995, 1996). An upward gaze of 10
deg above the horizontal plane was confirmed to increase the
OSA by about 12%. In addition, the rate of tear evaporation
per square centimeter increases with increases in OSA
(Tsubota and Nakamori, 1993). These findings may account
for the increased subjective complaints of dry eye or eye
irritation among VDT operators.
Shift in binocular vision; exophoria and dark vergence.
It
has been shown that the absolute average angle of exophoria
during upward gazing was significantly larger than during
lower gazing (Saito et al., 1993a). Moreover, dark vergence,
measured as the binocular convergence distance in a
completely dark room, was found to shift farther with an
upward gaze while a nearer shift occurred with a downward
gaze (Taptagaporn and Saito, 1993). Lowering the gaze
position also reduces the physiological efforts in binocular
vision. These characteristics of the oculo-motor system
objectively demonstrate that upward gazing as occurs with the
use of a larger screen may be physiologically more
uncomfortable.
The phenomena described above might cause physiological
and ergonomics problems in VDT workers. Particularly, these
disadvantages of using large screens are more serious for those
with a small physique, such as schoolchildren. A questionnaire
survey in schools indicates that most schools are slow to
develop instructive programs from environmental and
ergonomics viewpoints (Sotoyama et al., 2002).
Rapid introduction of the notebook computer
In 2008, notebook computer shipments exceeded for the
first time shipments of desktop computers in the world market.
Currently, using notebook computers in ICT classes in
elementary schools is the usual case. The use of notebook
computers in the workplace offers a number of advantages
over desktop computers from ecological viewpoints. On the
other hand, there are many visual ergonomics problems with
the LCD, such as luminance contrast (Saito et al., 1993b;
Kubota et al., 2006; Oetjen and Ziefle, 2009). In our previous
experimental study, a positive type CRT, which has dark
characters on a light background, was ascertained to be the
most appropriate display (Taptagaporn and Saito, 1990; Saito
et al., 1994), while working with an LCD was considered to be
the least visually comfortable with the lowest accommodative
velocity of the eye (Saito et al., 1993b). Although recent
technology has greatly improved the picture quality of the
LCD, the notebook computer has many ergonomics
disadvantages for the user in terms of visual fatigue and
constrained working posture (Saito et al., 1993b; Straker et al.,
1997; Villanueva et al., 1998; Jonai et al., 2002). The
distinctive working posture while using a notebook computer
with a flat panel display (FPD) was observed to be a
remarkably short viewing distance and a forward inclination of
the trunk and head/neck with higher neck muscle activity as
shown by electromyography (Jonai et. al., 1997; Villanueva et
al., 1998; Saito et al., 1997). Moreover, the construction of the
notebook computer contradicts the traditional ergonomics
recommendations for VDT use. The lack of tilt and swivel
mechanisms is an example of this oversight. Before
introducing the notebook computer into schools, it is
recommended that its ergonomics drawbacks be considered.
To overcome these drawbacks, ergonomics guidelines for
the use of notebook computers as issued by the JES and
IEA/TC/Human-Computer Interaction provide good solutions
for notebook computer users (Saito et al., 2000). Action
checkpoints developed by Iwakiri et al. (2004) are also useful
in making computer work comfortable, whether with notebook
computers or desktop computers. TCO Development
recommends in its documents for TCO’05 Notebooks 2.0 that
those who use a notebook computer as a stationary unit at
work should be able to connect them to external displays with
good image quality, to external keyboards and to external
pointing devices (mouse, digital pens, etc.) either as separate
units or via docking stations (TCO’05, 2005; TCO’05 Position
Paper, 2008).
JES ERGONOMICS ROAD MAP
At the turn of the century, JES identified and publicly
announced important ergonomics issues for the 21st century,
which subsequently evolved into the creation of the
Ergonomics Road Map. With a view toward contributing to
government policies and industrial research investment, JES
presented the road map to the public in 2006 (Fujita et al.,
2006). For information on the JES Road Map, visit the JES
web site; (http://www.ergonomics.jp/senryaku/index.html).
The current version of the JES Road Map consists of
following important ergonomics issues: work environments
and systems friendly to people, diversified needs in human life,
safe and comfortable mobility or barrier-free environment, safe
and healthy environments, good social communications, and
establishment of an educational basis for ergonomics for
children.
In order to extend ergonomics knowledge to the general
public including children and those working in schools, the
JES council plans to develop an ergonomics education for
elementary and junior high schools. The Ergonomics Road
Map can be a very useful tool for ergonomics communities in
terms of communicating with industry and policymakers and
providing a beacon that intends to provide general orientation
to academic research, industrial investment and an agenda for
policies of ministries, etc. Among important issues identified
in the map, establishment of an educational basis for
ergonomics for children was emphasized. In addition to
important issues in ergonomics such as a computer interface
tailored for children, it was suggested in the road map that
teaching ergonomics to children appears to be most critical,
and no doubt it will be essential to the proliferation of
ergonomics in the future in our society.
Acknowledgments
The author is grateful to the reviewers for their helpful
comments, and would like to acknowledge the efforts of his
colleagues for their contributions to the experimental studies
and questionnaire surveys, some of which are referred to in
this paper.
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