1. Introduction
Recent technological innovation including microelectronics and information
processing has rapidly increased the penetration of information technology.
With the widespread use of visual display terminals (VDTs) at worksites,
working environments and patterns have significantly changed. The recent
climate regarding VDT operations, since publication of "Industrial
Health Guidelines for VDT Operations" was formulated in December,
1985, includes the following:
(1) Increase in operators who are involved in VDT operations
(2) Widespread use of notebook-size personal computers
(3) Diversification of input equipment such as a mouse
(4) Widespread use of diversified software
(5) Increase in large displays etc.
(6) Widespread use of the Internet
(7) Widespread use of personal digital assistants.
As shown above, VDT operations at worksites have changed dramatically,
while problems related to current VDT operations have been pointed out.
According to an "Actual Condition Survey on Technological Innovation
and Labour" carried out by the Ministry of Labour in 1998, of workers involved in VDT operations, 36.3% experienced mental fatigue and as many as 77.6% experienced physical fatigue.
In order to reduce physical and mental burdens imposed on operators who are involved in VDT operations (hereinafter called "operators"), it is important for employers to create a working environment appropriate for VDT operations whenever possible and carry out proper operational controls to ensure that VDT operations are not carried out excessively over long periods of time.
Where operators become strongly aware of physical and mental burdens or are under abnormal physical conditions, it is required to improve the working environment and operational method at an early stage so that operators can conduct VDT operations without negative health effects.
In this regard, it is important for employers to have a sufficient understanding of health conditions of operators and administer health controls to ensure that appropriate countermeasures are taken according to operator health conditions at as early a stage as possible.
These Guidelines, based on the points of view above, describe countermeasures that employers should take to help operators reduce physical and mental burdens and conduct VDT operations without negative health effects, through reviews of working environment controls, operational controls, health controls, etc., in regard to VDT operations based on findings subsequently obtained in the areas of industrial health, human engineering, etc.
In order for such industrial health controls to be appropriately carried out, employers are required to define basic policies on safety and health, establish safety and health controls system, prepare a concrete safety and health plan through cooperation with each class of manager and operator and pursue industrial health controls activities, such as improvements in working environments, full-scale operational controls and reinforcement of health controls of operators, according to the plan systematically.
Since it is also extremely important that operators understand the objective
and actively cooperate thoroughly with these countermeasures, it is indispensable
to carry out appropriate industrial health education. These Guidelines
are targeted for standard VDT operations. Accordingly, it is important
that each business organization fully studies and discusses the guidelines
through a health committee and establishes industrial health control standards
on VDT operations according to the actual worksite situations of VDT operation.
In addition, a health committee must evaluate applicable these standards
at regular intervals and review these standards as required in order to
ensure standards comply with the operational reality at each worksite.
Furthermore, in order to manage the standards more accurately, it is effective that employers work as part of an autonomous industrial safety and health activities policy board continuously carried out by defining a series of processes through cooperation with employees based on the Guidelines for Industrial Safety and Health Management System (Official Notice No. 53 by the Ministry of Labour 1999).
2. Target operation
The target operation shall be VDT operations carried out at offices (offices specified in Clause 1, Article 1 of the Ordinance on Health Standards in the Office), which includes data input, retrieval, checks, etc., creation, editing and correction of text, images, etc., and programming and monitoring operations through the use of VDT equipment composed of displays, keyboards, etc. VDT operations shall be divided based on attachment of "Category of VDT operations" (hereinafter called "attachment"), and industrial health controls must be executed according to operation type and time.
However, for employees who are involved in operations applicable to "operation
category C" (hereinafter called "operators in operation category C"), industrial health controls must be executed as required according to 3, 4 and 5 below.
Even for VDT operations carried out at places other than offices, VDT operations carried out by home-based workers at home and operation similar to VDT operations, it is preferable to provide guidance on administrating industrial health controls according to this guidelines whenever possible.
3. Working environment control
In order to allow operators to conduct operations without negative health effects by reducing the physical and mental burdens imposed on them, working environment controls must be administered according to the following:
(1) Illumination and natural lighting
A. In offices, the contrast between natural light and shade must not be sharp with as little glare produced as possible.
B. Where a display is used, illumination of the display screen must be 500 lux or less and illumination of text and keyboard must be 300 lux or more.
Differences between brightness of the display, brightness of the text and keyboard surfaces and peripheral brightness must be as small as possible.
C. Where sunlight is incident on display screens directly or indirectly, a blind or curtain must be attached to the window as required to ensure appropriate brightness.
(2) Prevention of glare
For displays, glare must be prevented by taking the following countermeasures as required:
A. Adjustment of positions, fore-and-aft tilt and lateral orientation of display screens
B. Use of non-glare displays
C. Use of natural lighting fixtures for glare prevention, such as indirect lighting
D. Taking other effective countermeasures to prevent glare
(3) Noise reduction countermeasures
Where objectionable noise is produced from VDT equipment and its peripheral equipment, noise reduction countermeasures must be taken.
(4) Other
Countermeasures specified in the Ordinance on Health Standards in the Office, related to equipment for ventilation, temperature and humidity regulator, air conditioning, elimination of static electricity, breaks, etc., must be taken.
4. Operation control
In order to allow operators to conduct operations with reduced physical and mental burdens, operation time controls must be administered as shown below, while appropriate operation controls must be administered by upgrading VDT equipment and its related equipment according to operational features and characteristics of individual operators.
(1) Operation time etc.
A. Operation time per day
(a) Operation category A
For operators who are involved in operations applicable to "operation category A" in the attachment (hereinafter called "operators in operation category A"), it is preferable to ensure time to fix eyes on a display screen and time to operate keys as short as possible. In addition, consideration must be provided so that continuous VDT operations time per day can be shortened by incorporating other tasks or carrying out task rotations.
(b) Operation category B
Even for operators who are involved in operations applicable to "operation category B" in the attachment (hereinafter called the "operators in operation category B"), guidance must be provided in the same manner so that VDT operations are not carried out excessively for long periods of time.
B. One continuous operation time and operation downtime
(a) "Simple input type" and "binding type"
For operators who are involved in operations applicable to "simple input type" and "binding type" of "operation type"; in attachment, one continuous operation time must not exceed one (1) hour and an operation downtime of 10-15 minutes must be established before subsequent continuous operation. In addition, short breaks must be established once or twice within one continuous operation time.
(b) Types other than (a)
For operators who are involved in operations applicable to types other than "simple input type" and "binding type" of "operation type" in the attachment, guidance on establishing an operation downtime and short breaks must be provided in the same manner.
C. Consideration of operation volume
In order to prevent the accumulation of fatigue of operators, consideration must be provided so that operation volume is balanced by having a good understanding of the characteristics of each operator.
(2) VDT equipment etc.
A. Selection of VDT equipment
When VDT equipment is introduced to offices, equipment that is most suitable for operations conducted by operators must be selected considering the effects of operator health.
B. Desktop computers
(a) Display
A display that meets the following requirements must be used:
a. Screen size must be large enough for target VDT operations to be carried out with no burdens.
b. Flicker must not be perceivable.
c. It is preferable that brightness or contrast of display screens can easily be adjusted by operators.
(b) Input equipment (keyboard, mouse, etc.)
a. Input equipment that meets the following requirements must be used:
(a) It is preferable that the position of a keyboard can be adjusted by operators by separating it from the display.
(b) For keyboard keys, characters must be clear and easy to read while key size and number of keys must be appropriate for key operation.
(c) For a mouse, the shape and size must be suitable for the hand of a user and it must be easy to grasp and operate.
(d) For keyboard keys and mouse buttons, the stroke and push force must be appropriate, and it is preferable that operators perceive their operation.
b. Input equipment appropriate for target VDT operations must be available.
c. A palm rest (wrist rest) must be available as required.
C. Notebook-size equipment
(A) Use of appropriate equipment
Notebook-size equipment appropriate for target VDT operations must be used under proper conditions.
(B) Display
Displays that meet the requirement of (A) above must be used.
(C) Input equipment (keyboard, mouse, etc.)
Input equipment that meets the requirement of (b) of B above must be used. However, for notebook-size equipment of which a display cannot generally be separated from a keyboard, it is preferable to use an external keyboard when VDT operations are conducted with a small notebook-size equipment for long periods of time.
(D) Use of mouse
It is preferable that a mouse is available as required.
(E) Use of numeric keypad input equipment
When operations of numeric character input are frequently conducted, it is preferable that numeric keypad input equipment is available.
D. Personal digital assistants
For personal digital assistants, it is preferable to avoid VDT operations over long periods of time whenever possible.
E. Software
It is preferable to use the software that meets the following requirements:
(a) Software must conform to the characteristics of the target VDT operations as well as to the skill and abilities of each operator.
(b) Appropriate descriptions of software are provided to operators at their request.
(c) Settings of interface software can easily be changed according to operational necessity as well as to the skill and preference of each operator.
(d) If data is erased due to an operational error, data must easily be restored.
F. Chairs
Chairs that meet the following requirements must be used:
(a) Chairs must be stable and moved easily.
(b) Seat height from the floor can be adjusted to a proper condition according to the operator's size.
(c) When multiple operators use the same chair by rotation, the height of the chair can easily be adjusted and the seat must not fall structurally during adjustment.
(d) Chairs must have appropriate backs. It is preferable that the tilt of a back can be adjusted.
(e) Chairs must have armrests of the appropriate length.
G. Desk or workbench
Desk or workbenches that meet the following requirements must be used: (a) The working surface must be wide enough for operators to properly locate items required for VDT operations, such as a keyboard, document and mouse.
(b) The surrounding space of the operator's legs must be large enough for an operator so as not to experience a cramped feeling.
(c) The height of a desk or workbench must meet the following requirements:
a. When a desk or workbench of which the height cannot be adjusted is used, the height from the floor must be a height appropriate for the operator's size.
b. When a desk or workbench of which the height can be adjusted is used, the height from the floor can be adjusted to a height appropriate for the operator's size.
(3) Adjustment
In order to allow operators to conduct VDT operations with an unforced posture, operators must pay particular attention to the following items and adjust the height of chairs and the positions of keyboard, mouse and display comprehensively:
A. Operation posture
(a) As basic posture, an operator should sit back in the chair with his/her back appropriately squared to the chair back and his/her shoes must make contact with the floor. A foot rest that is sufficiently wide and slip proof must be prepared as required.
(b) Clearance must exist between the chair and the thigh knee-side back, to an extent to which a finger can enter. Forced pressure must not be applied to the thigh.
B. Display
(a) With a distance of sight of approx. 40 cm or more allocated, correction must be made with appropriate eyeglasses as required so that the display is easy to see.
(b) It is preferable that the top edge of the display screen be approximately as high as or slightly lower than eye level.
(c) The difference between the distances of sight to the display screen and that to a keyboard and text must not be excessively large, and an appropriate visual-field range must be kept.
(d) Displays must be adjusted to allow position, angle and brightness desired by the operator.
(e) Size of characters to the display screen must not be small, and character height must be kept 3mm or more.
C. Input equipment
The speed of a pointing device such as a mouse and movement speed of a cursor must be adjusted appropriately according to the operator's skill, preference, etc.
D. Software
The display capacity, number of display colors, size and shape of characters, background, character proportional spacing and line spacing must be adjusted individually to an appropriate level.
5. Maintenance control of VDT equipment and working environment In order to consistently maintain the working environment in good condition and ensure that the condition of the VDT equipment is appropriate for VDT operations, checks and cleaning must be carried out according to the following and a course of action must be taken as required:
(1) Daily checks
Operators must check natural lighting, prevention of glare, ventilation, elimination of static electricity, etc., as well as the display, keyboard, mouse and desk or workbench, before operations start or during an appropriate time of day, as part of routine work.
(2) Periodic check
A periodic check must be carried out, with regard to control conditions of illumination and natural lighting, prevention of glare, noise reduction, ventilation, temperature and humidity regulator, air conditioning, elimination of static electricity, as well as the adjustment conditions of a display, keyboard, mouse, chair and desk or workbench.
(3) Cleaning
The work area, VDT equipment, etc., must be cleaned daily and periodically to maintain the right conditions.
6. Health controls
In order to have a good understanding of the health conditions of operators and prevent health ailments, health controls must be carried out for operators according to the following:
(1) Medical check-ups
A. Medical checkups before actual work assignment
(a) Operation category A
In order to understand the health conditions of operators who will fall under operation category A (including those reassigned) prior to actual work assignment and in order to pursue subsequent health controls appropriately, medical checkup must be carried out with regard to the following items:
a. Check of occupational history
b. Check of medical history
c. Check of presence of subjective symptoms
(1) Symptom related to vision including eye fatigue (asthenopia)
(2) Symptoms related to the musculoskeletal system including the upper extremity, neck, shoulder and arm and lower back
(3) Symptoms related to stress
d. Ophthalmological examination
(1) Eyesight examination
i. 5-m eyesight examination
ii. Near vision examination
(2) Refraction examination
(3) Eye position examination
(4) Eyesight adjustable function examination Eyesight adjustable functions are tested with measurement of near-point distances.
e. Musculoskeletal system examination
(1) Upper-extremity motor function and tender point examination
(2) Other examinations observed as necessary by a physician
(b) Operation category B
For operators who will fall under Operation Category B, checks of a, b and c above, as well as an examination of d, must be carried out. An examination of e must also be provided to those who are observed as requiring examinations as recommended by a physician.
(c) Operation category C
For operators who fall under operation category C, the required check or examination in a above must be provided to those who have recognizable symptom.
Where a general medical check-up (specified in Clause 1, Article 66 of the Industrial Safety and Health Law) is carried out before or after a medical check-up prior to actual work assignment, check or examination above can be carried out in conjunction with the general medical check-up.
B. Periodical medical check-up
(a) Operation category A
In order to periodically understand the health conditions of operators
after actual work assignment and to continuously pursue health controls
properly, a medical check-up must be provided periodically (annually) to
operators in operation category A, with regard to the following items:
a. Check of occupational history
b. Check of medical history
c. Check of presence of subjective symptoms
(1) Symptoms related to vision including eye fatigue
(2) Symptoms related to the musculoskeletal system including the upper extremity, neck, shoulders and arms and lower back
(3) Symptoms related to stress
d. Ophthalmological examination
(1) Eyesight examination
i. 5-m eyesight examination
ii. Near vision examination
(2) Other examinations observed as necessary by a physician
e. Musculoskeletal system examination
(1) Upper-extremity motor function and tender point examination
(2) Other examinations observed as necessary by a physician
(b) Operation category B
For operators in operation category B, checks of a, b and c above must be carried out. Examinations of d and e must also be provided to those who are observed as requiring examinations as recommended by a physician.
(c) Operation category C
For operators in Operation category C, required check or examination in a above must be provided to those who have recognizable symptom.
The check or examination above can be carried out in conjunction with a general periodic medical check-up (specified in Article 44 of the Ordinance on Industrial Safety and Health).
C. Post action to be taken based on medical check-up results Negative health-inducing factors found at an early stage prior to actual work assignment or periodic medical check-up must be analyzed in detail. Appropriate action, such as health guidance shown below, must be taken as required for those under a physician's observations, and preventive countermeasures must be established.
(a) Main causes for complaints must be identified through a check of occupational history, subjective symptoms, various examination results, etc. Health controls must be pursued as required in such a manner as to provide health guidance and advice based on consultations with a medical specialist, and operation methods and the working environment must be improved. Even where causes are found not only on the job but also off the job, required health guidance must be provided.
(b) For operators for whom vision correction is improper with regard to distance of sight for VDT operations, required health guidance must be provided so that VDT operations can be carried out without negative health effects.
(c) For operators who are observed as being inappropriate for continuing VDT operations and those who are identified as requiring a reduction in VDT operations time, appropriate countermeasures must be taken to maintain the health of those operators considering the opinions of an industrial physician.
(2) Health consultation
In order for operators to be able to seek a consult in regards to health and receive appropriate advice without reserve, opportunities for heath consultation, regarding mental health, health concerns, chronic fatigue, symptoms of stress etc., and self-guidance methods, must be provided, with consideration for the protective of privacy. In addition, it is preferable to provide special consideration, such as upgrading of the environment in which all operators including part-time workers can seek a consult without reserve.
(3) Workshop exercises
It is preferable to administer, stretching, relaxation, light exercise, etc., before and after work or while at work.
7. Industrial health education
Industrial health education shown below must be carried out, in order to improve the working environment and operation methods at worksites, with smooth administration of appropriate health controls and a reduction in physical and mental burdens due to VDT operations by ensuring the objectives and methods of various countermeasures for industrial health controls made known to operators.
Training required for learning VDT operations must also be provided to operators who will be newly engaged in VDT operations. When education and training are carried out, it is preferable to administer these according to the plan and record the execution results.
(1) Education must be provided to operators, with regard to the items shown below. In addition, it is preferable to provide education even in regards to the knowledge required for applicable operators to voluntarily maintain, control and build up their health.
A. Effects of VDT operations on health
B. Illumination, natural lighting and prevention of glare
C. Operation time etc.
D. Operation posture
E. Adjustment and usage of VDT equipment etc.
F. Maintenance and control of the working environment
G. Medical check-ups and post action to be taken based on related results
H. Health consultation system
I. Workshop exercises
J. Other industrial health precautions associated with VDT operations
(2) For those who directly manage operators involved in VDT operations, education must be provided with regard to the following items:
A. Roles and mental attitudes of managers
B. Concepts of industrial health controls
C. Effects of VDT operations on health
D. Illumination, natural lighting and prevention of glare
E. Operation time etc.
F. Operation posture
G. Adjustment and usage of VDT equipment
H. Maintenance controls of the working environment
I. Medical check-up and post action to be taken based on related results
J. Health consultation method
K. Necessity and method of workshop exercise
L. Educational method for those who are involved in VDT operations
M. Considerations
N. Other industrial health precautions associated with VDT operations
8. Considerations
(1) Considerations for senior employees
Illumination conditions and character sizes of displays must be set in such a manner as to allow each older operator to have a clear view, and it is preferable to take into consideration operation time and volume so that burdens will not be placed on senior operators. In addition, it is preferable to give consideration to operators whose learning speed is slow, by providing additional education/training to them according to their level.
(2) Considerations for operators with disabilities
Countermeasures must be taken as required to ensure that operators with disabilities who find it difficult to use a keyboard or mouse, VDT operation input equipment are offered voice input devices etc.
In addition, for those who find it difficult to read displays even with appropriate vision correction, countermeasures must be taken as required to ensure that they are offered enlarged displays or displays for weak-sighted people.
(3) Considerations for home-based workers
It is preferable for job orders to provide home-based workers who are involved
in VDT operations with the contents of these guidelines to ensure home-based
worker health.
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