Cornell University Ergonomics Web
Performance Oriented Ergonomic
Checklist For Computer (VDT) Workstations
(adapted from ErgoWeb,1996, by the Cornell University Human Factors Group, Dept. Design & Environmental
Analysis, 1996)
Introduction
Among Ergonomists there is general agreement with
regard to proper computer workstation set-up, and the optimal body postures
assumed by people performing tasks at the workstations. Unfortunately, quick
and easy solutions to ergonomic problems, such as wrist rests, seldom help
and sometimes they actually make matters worse. Likewise, recommending specific
dimensions for workstations without knowledge of the anthropometrics of
each user, the dimensions of equipment, and the nature of the work to be
done can result in sub-optimal workstation arrangements. For more information on
computer workstation arrangements check out the 10 tips
page.
This performance oriented checklist is designed to
help you to evaluate what is needed for a good ergonomic workstation arrangement.
Specific dimensional constraints intentionally are omitted and replaced
by a principles oriented approach for this checklist. A checklist
is a guide to good decision making, not an end point in itself. No checklist
alone is able to capture the interactions and complexities of all possible
combinations of people, task, equipment, and work environment. However,
use of this checklist, along with an understanding of the principles of
Ergonomics, will allow you to identify workstations which need redesign
work, and it will give you guidance on the goals of any workstation redesign
that is required.
At a minimum, while using this checklist, remember
that designing for ergonomics requires understanding and consideration of
- the physical and psychological attributes of the person or population
of people that will perform the job
-
the design and arrangement of the workstation furniture, computer hardware,
computer software, and other workstation accessories
-
the tasks required to perform the job
-
the work environment, including such things as noise and temperature,
but also management and organizational methods and constraints
The interaction between these general topics is critical,
and will define the postures, forces, and repetitions assumed by the person(s).
Remember, all parts of the body are linked together, and consequently a
modification in one area may have significant effects in another, no single
change can be performed without considering the effects on other areas.
For example, lowering seat height so that someone may comfortably rest his/her
feet on the floor may force a stressful upper body posture if the monitor
position and table or keyboard height are not adjusted in concert (this
is often a good reason to provide a footrest).
When using this checklist,
ask not whether the person can merely achieve these general goals,
but whether the design of the workstation, task, and environment interfere
with, obstruct, or outright inhibit a person from achieving them.
remember that it is worded for use when reviewing one person and that
person's VDT workstation, tasks, and working environment. If more than
one person must use the same workstation, the checklist should be applied
to each individual, and an easily adjustable workstation becomes even more
important.
remember that there is no "perfect posture for all time"
and that a dynamic posture (frequent changes in posture) is a good way
to reduce stress and redistribute pressure related to long duration static
postures. However, work can be sustained for longer times without causing
harm if the person is working in a neutral posture.
remember that the checklist is not all inclusive, and may not cover
all of the topics important to your specific situation.
remember that a good ergonomics approach will improve comfort, productivity
and quality, as well as health and safety.
"NO" responses indicate conditions that
may be associated with higher risk of illness/injury and steps should be
taken to address the source of the problem. "YES" responses to
questions indicate acceptable ergonomic design conditions.
VDT Posture Checklist
1. POSTURE
"NO"; answers to ANY posture question identify
the item that may be contributing to ergonomic risk and this should be addressed
immediately. For a more detailed and systematic analysis of postural risks
this checklist should be followed up by undertaking a Rapid Upper Limb Assessment
( RULA) analysis of the worker's posture.
Lower Extremities
Is the person able to rest the feet comfortably?
Is the person able to sit with the knees in a comfortable position?
Is the person free of uncomfortable pressure points, obstructions,
or other interferences in the lower extremities?
Upper Extremities
-
Is the person able to work with the head in a vertical orientation,
such that the neck is not stressed by holding the head off balance from
the neck and shoulders?
-
Is the person able to work with the head facing forward of the plane
of the upper body the majority of the time, such that repetitive or long
duration head rotation is minimized?
-
Is the person able to reach to objects on the workstation without extended
reaching, especially where the reaching is held for long durations, is
repetitive, or requires trunk/torso deviations?
Is the person able to work with comfortable arm positions,
or approximately:
neutral shoulder positions (upper arms tucked close to the body and
hanging relaxed, not abducted out to the side, extended forwards or backwards,
raised up, or hunched)?
comfortable elbow positions that do not force shoulder or elbow positions
from approximately neutral?
neutral wrist positions (hands in a straight line with the lower arms,
hands not flexed down towards the palm not extended up, nor bent towards
the little finger, nor bent towards the thumb)?
Force Static Body Posture
Do the workstation design and job requirements cause non neutral body
positions to be held constant for extended periods of time?
2. WORKSTATION AND ENVIRONMENT DESIGN FEATURES
Seat Surface
Is the seat surface height adjustable, such that the person is able
to set it at an individually comfortable height in relation to the required
work activities?
Is the seat surface of appropriate size, such that it is deep and wide
enough to comfortably accommodate the specific person?
Is the seat slope adjustable, such that the person is able to achieve
a comfortable angle, either forward or rearward sloping?
Is it comfortable and is the front well rounded ("waterfall" front
edge), such that the person does not experience excess pressure on the
under side of the leg due to the forward edge?
Overall, is the seat comfortable to the person that is required to
use it?
Seat Backrest
Can the person easily adjust its height to provide mid lumbar support
(lower back region)?
Can the person easily adjust its angle relative to the seat surface?
Can the person easily adjust it to alter the depth of the seat?
Overall, is it comfortable to the person that is required to use it?
Worksurface
-
With the lower limbs in comfortable positions and feet on the floor,
can the person achieve a comfortable worksurface height?
-
Is the width of the worksurface appropriate, such that all required
task accessories and duties can be located within comfortable reach and
viewing distance?
-
Is the depth of the worksurface appropriate, such that the computer,
and keyboard if necessary, can be placed directly forward of the person
with the work orientation parallel to the plane of the upper body?
-
Is the area under the desk large enough to accommodate the legs and
any accessories, such as footrests and arm rests.
Computer Monitor (VDT)
Is the person able to easily adjust the height of the monitor?
Is the person able to easily adjust the fore-aft distance of the monitor?
Is the person able to easily adjust the tilt (up/down) angle of the
monitor?
Is the person able to easily adjust the yaw angle (left/right rotation)
of the monitor?
Keyboard
Is the keyboard detachable from the VDT/computer monitor?
Is the person able to easily adjust keyboard height?
Is keystroke pressure comfortable to the person?
Has the person correctly adjusted the angle of the keyboard so that
their hands/wrists are in a neutral posture when they are typing? Placing
the keyboard in a preset angle negative tilt keyboard tray that is height
adjustable allows users to access the keyboard in a wrist neutral posture.
Mouse
Is the shape and button activation comfortable and easy to operate
for the person?
Is the person able to reach and operate the mouse without extended,
long duration, or repetitive reaching and with the shoulders, arms and
wrists in a neutral posture?
Is the mouse on a position adjustable platform surface, so that this
can be used within the person's immediate reach zone?
Document Holder for Data Entry Tasks
Is there a special holder or support for the source document?
Is the person able to easily adjust the document holder height, distance
and angle?
Does the device prevent the document from vibrating?
Is the device located such that the person is not required to twist
the head/neck back and forth between the document and screen extensively
or for long durations?
Support for the Hands and Arms
Are seat or other padded armrests available?
Are armrests adjustable (height, lateral position)?
Is a broad, flat keyboard palm support available to support the hands
in a neutral posture in between bursts of typing movements? (Not a wrist
rest. Most wrist rests are soft and curved. They can put extra pressure
on the carpal tunnel which lies at the wrist increase, and this increases
the risk of an ergonomic injury).
Is the palm supported for mouse use?
Support for the Feet
Are the feet flat on the floor when the person is sitting comfortably
at the workstation?
Is a footrest available if needed and can the person able to easily
adjust its height and its tilt?
Office Lighting
Are lighting levels in the VDT/computer monitor area comfortable to
the person?
Is the monitor screen placed such that light from windows and overhead
lighting do not cause glare? If not, are glare screens or other glare reducing
methods used?
Are diffusers, cube louvers or parabolic louvers used on overhead lights
where screen glare from that source is a problem, or is indirect lighting
used?
Are movable task or desk lights available?
Do work surfaces have a matte finish to reduce light reflection?
Do windows have curtains, drapes or blinds to block light where glare
from that source is a problem?
Temperature
Is the person comfortable with the ambient temperatures?
Is the person comfortable with the temperatures of any equipment or
surfaces s/he must contact?
Vibration
-
Does the person experience any uncomfortable building vibration (e.g.
from mechanical systems, outside traffic)?
-
Does the person experience any uncomfortable equipment vibration (e.g.
from internal fans)?
-
Does the person experience any uncomfortable keyboard vibration (e.g.
wobble from an unstable keyboard tray)?
Noise
Are sound levels at comfortable levels, allowing conversation and other
communications without significant effort?
Does the person experience any uncomfortable equipment noise sources
(e.g. printer noise)?
Ventilation
Is air circulation sufficient?
Is air quality satisfactory?
Is the air too dry or too humid?
Electrostatic Electricity
Does the person frequently experience static electricity shocks?
3. THE WORKER
Fatigue Control
Is the person allowed to take rest pauses or breaks from tasks that
require long duration or repetitive postures, forces, keying or mousing
activities?
Is there job rotation or substitution of tasks which require a different
type of activity where posture, force, and repetition hazards have not
been addressed by design?
Vision
Does the person wear bifocal glasses, causing him/her to tilt the head
to see through the appropriate lens area?
Are workers with symptoms of eye strain, burning sensation in the eyes,
blurred vision, irritated eyes, or headache examined for vision problems?
Psycho-Social Issues
-
Does the person have some involvement and control over the work process?
-
Is there good communication between the person and supervisors?
-
Has the person been adequately trained?
-
Is the software "user-friendly"?
If you answered "NO" to any of the questions
in the Worker section, administrative issues which may be contributing to
ergonomic risk. A review of training and other administrative policies is
recommended.
A note regarding "ANSI/HFES 100-1988,
American National Standard for Human Factors Engineering of Visual Display
Terminal Workstations."
The recommendations in "ANSI/HFES 100-1988, American
National Standard for Human Factors Engineering of Visual Display Terminal
Workstations.", while often relied upon for ergonomics guidance, are
influenced more by anthropometry (body dimensions) than by the full spectrum
of ergonomics principles that should guide the design of furniture, tools,
equipment, and tasks for computer workstations. ANSI/HFES 100-1988 is centered
around the "upright" sitting posture, sometimes referred to as
the "90-90-90", or "90 degree" posture, indicating the
approximate joint angles at the hip, knees, and elbows. This is not
the only posture available for seated workers, not the only posture
supported by furniture designed to be used for computer intensive work,
and not a recommended working posture for sustained periods. ANSI/HFES
100-1988 is currently being revised, and is scheduled to be open for public
review in the near future.
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