The best way to make your brain with no strain even if
you work hard by your sitting positions and space management. These techniques
will help you to improve your health by sitting according to below rules.
Ergonomics is the science of fitting jobs to workers by taking into account the
requirements of the job and peoples’ physical and mental capacities. It is the
science of ergonomics that is used to design an appropriate computer
workstation. When workstations are not designed appropriately, when
non-ergonomically designed computer equipment is used and when jobs and tasks
are not well organized, anumber of computer related health problems can
arise.
Eye and vision problems
Eye and vision problems have been reported; in fact, eye and vision
complaints are the most common complaints of computer users. Vision problems
can contribute to the physical disorders. We tend to position ourselves so that
we can see the images on the monitor, keyboards and documents. However if our
vision is blurry, we may lean forward and crane our necks to get a closer look.
Such awkward positions increase the risk for physical disorders. It is
therefore important to have regular eye check ups. In addition, computer work
tends to exacerbate other vision problems. Special computer glasses exist that
may help with computer work. Adequate lighting and the prevention of glare also
play a role in how our vision is affected during computer use. Eye and vision
problems have been reported; in fact, eye and vision complaints are the most
common complaints of computer users. Vision problems can contribute to the
physical disorders listed below. We tend to position ourselves so that we can
see the images on the monitor, keyboards and documents. However if our vision
is blurry, we may lean forward and crane our necks to get a closer look . Such
awkward positions increase the risk for physical disorders. It is therefore
important to have regular eye check ups. In addition, computer work tends to
exacerbate other vision problems. Special computer glasses exist that may help
with computer work. Adequate lighting and the prevention of glare also play a
role in how our vision is affected during computer use. Stress
Stress is also reported by computer users. The National Institute of
Occupational Safety and Health found that operators of computers experience
more job stress than any other occupational group it has studied. Work related musculoskeletal disorders, also
known as Cumulative Trauma Disorders or Repetitive Strain Injuries, are a group
of health problems caused by over-use or misuse of muscles, tendons and nerves.
A good computer workstation layout can reduce the risk of
experiencing computer related health problems. A good workstation layout as
shown in Figure 1 should allow the computer user flexibility to reach, use and
read the computer monitor, keyboard, mouse, source document, document holder,
phone and other office accessories. Therefore, how we arrange the workstation
to fit our individual needs is probably the most important consideration to
work comfortably. There are no established guidelines on how you should
position your computer, it all depends on your comfort.
Some
tips that can be followed to arrange your workspace:
1. Ensure there is sufficient desk space to allow you to
put your keyboard, mouse, computer monitor, document holder, telephone and
other accessories within a comfortable reach. A good rule of thumb is to have
everything you need within a 16" reach.
2. Avoid clutter and crowding by adding shelves or file
cabinets.
3. Position the work materials and the office equipment
used regularly in front of you so that you do not have to constantly reach out
and put yourself in an awkward posture. • If you spend a lot of time on the
phone and computer at the same time, use a headset to prevent you from reaching
or cradling the phone in your neck.
4. If you need to move around while on the phone to get
access to files, use a cordless headset or a longer cord to prevent over
reaching and awkward posture. Don’t
& do’s
Space
& positioning
Space
In a multi task office environment where a computer is a
necessity, it is important that the workstation provide maximum flexibility to
accommodate not just the equipment, but also the space required for the task,
an L-shape desk, which is ideal for working at the computer on one side of the
desk, and provides space to do non-computer tasks on the other side. In
addition, this set-up places the computer screen, keyboard, mouse, phone, task
light and document holder in a centralized location and within the 16"
radius, which prevents reachingout when using the equipment.
Positioning
In designing a
workstation, the type of task performed at the computer may determine the
workstation layout. The placement of the computer monitor, input devices and
computer accessories should be matched to the task. For example, proper
keyboard location depends on how often the keyboard is used, whether the keying
activity is a one- or two-handed task and how often visual guidance is required
to locate specific keys during the task.
Work
space positioning for: Data Entry
In a data entry job, the computer
user concentrates more on looking at the source document, with only brief
glances at the monitor. Frequently the data input is numerical in nature. The
keyboard placement and the use of document holder are important. For data
entry, it is best to place the keyboard directly in front of the keying hand
and leave a large area free for the activity of the other hand. There should be
sufficient work surface space to perform these tasks.
Work
space positioning for Data Retrieval
In data retrieval, the computer user brings up
information from the computer and reads it on the monitor, or scans for
specific information, often writing it down. The user mainly looks at the
monitor; therefore, the placement of the monitor is more crucial than the
keyboard and document holder. Adequate space for writing is also important.
Work space positioning for: Word
Processing
Word processing tasks require both data entry and data
retrieval. The user spends about half of the time viewing the monitor and the
other half at the source document. Therefore, the placement of the monitor,
keyboard and the document holder are all equally important. Text entry requires
equal use of both hands for keying, so the keyboard should be directly in front
of the user and at a comfortable height.
Work
space positioning for: Graphic Design
In designing graphics and drawings, the user relies on
the mouse and bit pen to enter the information in the computer. The user
constantly looks at the monitor. Therefore, the monitor should place directly
in front of the user, with easy access to the mouse.
Desks
As people come in different heights and perform different
tasks, the computer desk should provide adjustability in order to minimize
stressful posture and reaching. The workstation should be adjustable to
accommodate individual workers for all applications. The dimensions of the computer desk should
be such that:
1. An ideal
computer desk should have two levels with each level adjustable for height. One
level is for the monitor and one for the keyboard and mouse. The level for the
monitor should be at least 20" wide (24" preferred) to provide
adequate work space for the monitor, document holder, and other equipment
needed for all tasks performed at that workstation.
2. Most
people do not have a computer desk and use their computers on a regular work
desk. As work desks are not adjustable it then becomes important that an
adjustable chair and keyboard tray be available. 2. Adequate clearance under the desk should
be provided for the computer user’s legs and feet. According to PEOSH VDT
guidelines, one way to ensure the clearance requirement is to image an object
shaped like a "clearance envelopes", and to provide that amount of
space. 3. The height of the top surface
of the keyboard tray from the floor should be adjustable to a range of
23"- 28". The keyboard tray should also allow the user to adjust the
angle of the surface so that the user’s wrists and elbows can be in neutral or
slightly downward position during keying
4. The computer desk should be height adjustable so that the topmost
line of the computer monitor is eye level for the user. The height of the
monitor surface should permit the location of center view of the screen to be
between 5 to 30 degrees below the horizontal plane through the eyes. Appropriate
display height can be accomplished by adjusting the display surface or
installing a monitor stand that is height adjustable. If the monitor is too
low, the monitor height can be raised by stacking monitor risers/books or
installing a computer support arm. If the monitor is too high, take the monitor
off the computer processing unit, or lower the desk, or raise the chair and
obtain a foot rest.
The preferred
viewing distance for the monitor ranges between 18 and 24 inches
Chair
Chair Height
The chair height should:
1. Allow
the user to rest the entire sole of his or her foot on the floor or footrest.
2. In combination with the work surface heights, allow
the user to achieve a suitable keyboard to forearm relationship and adequate
leg clearance. The forearm should be parallel to the floor and the wrists in
the same plane as the forearm.
3. Be adjustable from seated position without tools. The
minimum range of adjustment should be 16-20.5 inches.
Backrest
A
proper backrest should:
1. Support the entire back including the lower region and
provide a comfortable posture that permits frequent variation in a sitting
position.
2. Have the backrest angle and height easily adjustable.
The backrest should be able to tilt at least 85 degrees to 100 degrees while
still able to maintain at least a 90 degree sitting angle.
3. Have range height of 16-20 inches from the seat pan
and at least 13 inches wide.
4. have sufficient tension to provide adequate support
for the lumbar area as well as the middle and upper back.
5. Have a lumbar support that protrudes 1-2 inches and
runs across the backrest. The width of the lumbar support should be at least 12
inches and the height of the lumbar support (measure at the center of the
lumbar support) from the seat should be adjustable to a range of 6-10 inches. A
range of adjustability of more than 3 inches is desirable if the lumbar support
height is adjustable. Seat Pan
The seat pan should
1. have enough
depth to allow contact between the user’s lumbar region and the seat back. The
depth of the seat should be between 15 to 18 inches and 18 inches wide. • have
a "waterfall" design at the front of the seat, i.e. slightly concave
with a softly padded round edge. The purpose of the "waterfall"
design is to avoid pressure on the back of the leg above and below the knee. •
allow the user to adjust its angle and should ensure the angle between the
upper and lower leg is at least 60 degrees and no more than 100 degrees when
the lower leg is perpendicular to the floor. The adjustment range should allow
backward tilt to at least 8 degrees (10 degrees preferred) and forward tilt to
a maximum 5 degrees from horizontal. Because some tasks require leaning
forward, such as reading poor quality documents, leaning forward should be
accomplished by tilting the seat, not the torso, as sitting at less than 90
degrees from the thighs puts pressure on internal organs.
Keyboard
and Mouse
The keyboard and mouse support surface (also known as
keyboard tray/platform) plays an important role as it allows you to position
yourself in a proper body posture which will reduce the risk of developing
computer related injury.
There are several advantages of having a adjustable
keyboard tray; it:
1. Allows you to adjust it to the proper height so that
you can have knee clearance.
2. Allows you to adjust it so that you are not too far
nor too close when looking at the monitor. The preferred viewing distance for
the computer monitor ranges between 18 and 24 inches.
3. Allows you to position yourself in a neutral position
while keying. The preferred body posture is elbows and hands parallel to the
floor and wrists straight or slightly in a downward position.
4. Allows you to avoid unnecessary arm extension when
keying or mousing.
5. allows you to free up more work space on your desk for
other tasks, and
6. Allows you to easily store away the keyboard when it
is not being used.
Keyboards Keying
on a computer keyboard has been associated with causing musculoskeletal
disorders because of the improper placement of the keyboard in the workstation.
When a keyboard is placed on a desk or other surface which is not at the
correct height, or on a keyboard tray which is not ergonomically designed, this
causes the wrist to bend outward (A) and upward (B) which increase the risk of
injuries while keying on the keyboard. EOHSS recommends using height adjustable
keyboard trays with a mouse platform rather than investing in the
alternativekeyboards.
Wrists
bent outward
Wrists
bent upward
Pointing Devices
With more and more of the computer programs designed in window
environment and an increasing popularity in the internet, the use of the mouse
over keying has also increased. Unfortunately, there has also been an increase
in mouse-related injury.
The
following cause the most mouse-related injuries:
Mouse
position
People often place their mouse away from their bodies,
especially when their desks have a small keyboard tray that cannot accommodate
a mouse. Then the mouse is likely to be up on the desktop, causing them to
reach and extend their arm which requires greater shoulder action. When this
situation occurs the shoulder is required to act frequently, resulting in
fatigue and potentially a repetitive strain of some shoulder muscle’s
Grip Many
people have developed musculoskeletal disorders from holding the mouse with too
great a force. By squeezing the mouse tight it can cause the hands and arms to
tire easily and may lead to possible muscle strain.
Mousing postures
As to the keyboard, many people tend to hold and move
their mouse in awkward postures as shown in Figure 1. These postures impose
abnormal forces on the tendinous structures of the wrist which can lead to
fatigue, pain and injury. Incorrect
Mouse Postures
Force
and awkward wrist movement
Many people use tremendous force to drag and move the
mouse up and down and from side to side to move the cursor to the desired
point. The unresponsiveness of the mouse is due to losing contact with the
mouse pad or clogging of the ball mechanism. In addition, some people bend
their wrist inward or outward when mousing which increases the risk of injury
Monitors
Most new computers have separate, adjustable keyboards
and monitors that allow the keyboard and monitor to be positioned appropriately
for the user. This is important because depending on the tasks, the computer
user may spend a considerable amount of time viewing the monitor.
There
are some basic features to be considered when choosing a monitor:
1. The monitor
should be adjustable for tilt. By tilting the monitor, bright spots or washout
caused by the overhead light on the monitor screen, can be reduced. In
addition, it is also recommended to tilt back the monitor so that the top is
slightly farther away from the eyes than the bottom. As we look around our
surroundings, objects in the upper part of our peripheral vision are generally
farther away than the point we are looking at, and objects in the lower part of
our peripheral vision are usually closer. As a result, our visual system has
developed to perform best when the visual plane tilts away from us at the top.
2. The monitor should be able to swivel horizontally.
Depending on the tasks, the user should be able to adjust the monitor for an
optimum viewing angle. See Workstation layout for monitor arrangement for
specific task.
3. The monitor should be adjusted for brightness and
contrast. The brightness and contrast adjustment panel is usually located in
front of the computer monitor. The brightness of the monitor should match the
brightness of the surroundings to avoid eyes strain. It is easier to read the
monitor if the contrast of the monitor is adjusted correctly. Contrast is the
difference in brightness between the image produced by the monitor and the
image reflected off the monitor. In addition, it is also preferable to view a
monitor that has white or light color than a dark color background. Working on
a computer program that has black letters and white background can reduce the
difference in contrast between the screen and what is reflected off it.
4. All exposed surfaces of the monitor should be finished
in a neutral color with a non-reflective matte finish to minimize bright color
and glare from the these surfaces.
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