Unit 5

Human factors

•Human Error, Accidents, and Safety, Human relation in

industry, Introduction to computer-aided ergonomic
workstation analysis. Assessment of postures and
identification of risks to body regions. Performance
appraisal, Human Factors in Systems Design, Human
resource management.
Safety, Accidents, and
Human Error
Safety and Accident Prevention

• Accidents caused by multiple factors Link to story of Phineas Gage

• e.g., “human error,” equipment failure, improper equipment design,

environmental factors, or interaction between factors
• Accident deaths and injury in the U.S.
• 47,000 motor vehicle-related deaths / year
• 13,000 deaths due to falls /year
• 7,000 deaths due to poisoning / year
• Cost of Workplace deaths and injuries
• $48 billion / year
• $780,000 / victim cost to society
• $420 cost / worker
Most Frequent Causes of Workplace Deaths and
Injuries
Injury Deaths
Overexertion Motor-vehicle related
Impact accidents Falls
Falls Electrical current
Bodily reaction to chemicals Drowning
Compression Fire related
Motor vehicle accidents Air transport related
Exposure to radiation/caustics Poison
Rubbing or abrasions Water transport related
Exposure to extreme temperatures Other
Factors that cause or contribute to accidents
• The systems approach- accidents occur because of the
interaction between system components
• Direct causal factors in safety
1 the employee performing a task
2 the task itself
3 any equipment directly or indirectly used in the task
4 other factors - social/psychological & environmental
Personnel Characteristics
Factors affecting hazard recognition, decisions to act
appropriately, & ability to act appropriately
• Age & Gender
• younger people have more accidents - ages 15-24, mostly
young males
• Job Experience
• 70% of accidents occur within the first 3 years
• Stress, Fatigue, Drugs, & Alcohol
• many employers drug test
Job Characteristics/Equipment
• Job characteristics – such as high physical workload,
high mental workload, monotony, etc…
• Equipment - where most of the safety analysis is
performed. This is due to problems with:
• Controls and Displays
• e.g. poorly designed, difficult to use, cumulative trauma, etc.
• Electrical Hazards
• e.g. occurs when a person is doing repairs and another person
unknowingly turns the circuit on
• Mechanical Hazards
• results in cutting of skin, shearing, crushing, breaking, or straining
• Pressure and Toxic Substance Hazards
• asphyxiants, irritants, systemic poison, & carcinogens
The Physical Environment
• Illumination
• Glare, phototropism, contrast
• Noise and Vibration
• affects dexterity, control, and health
• Temperature and Humidity
• heat exhaustion, inattention, restrictive clothing
• Fire Hazards
• open flames, electric sparks, & hot surfaces
• Radiation Hazards
• Radioactive material - damage to human tissue
• Falls
• resulting in injury or death are relatively common
The Social Environment
• Human behavior is influenced by social context
- Social norms, mgmt practices, morale, training,
incentives
• e.g. construction workers will not wear safety gear if no
one else is
Human Error
Mars Orbiter

• The Misnomer of Human Error – error usually triggered by

other things (e.g., poor design, management, violations of
use and maintenance).
• Error is the end result of these problems
• Pilot error blamed on over 70% of airplane accidents
• Operator error blamed on over 60% of nuclear power plant accidents
• Doctor/Nurse errors in ICU occur at a rate of 1.7/patient per day
• Classifying types of error
• errors of omission - operator fails to perform a procedural step
• errors of commission - operator performs extra steps that are
incorrect or performs a step incorrectly
Taxonomy of Human Error

MISTAKES SLIPS

Knowledge Rule

Interpretation Plan
Stimulus Action
Evidence Situation Intention of Execution
Assessment Action

LAPSES &
MODE ERRORS
Memory
Taxonomy of Human Error
Mistakes
• Mistakes – failure to come up with appropriate
solution
• Takes place at level of perception, memory, or cognition
• Knowledge-based Mistakes – wrong solution
because individual did not accurately assess the
situation.
• Caused by poor heuristics/biases, insufficient info, info
overload
• Rule-based Mistakes – invoking wrong rule for
given situation
• Often made with confidence
Taxonomy of Human Error
Slips
• Slips – Right intention incorrectly executed (oops!)
• Capture errors – similar situation elicits action, which may
be wrong in “this” situation. Likely to result when:
• Intended action is similar to routine behavior
• Hitting enter key when software asks, “sure you want to exit without
saving?”
• Either stimulus or response is related to incorrect response
• Hit “3” instead of “#” on phone to hear next message, because “3” is
what I hit to hear the first message
• Response is relatively automated, not monitored by consciousness
• Re-starting your car while the engine is already running
Taxonomy of Human Error
Lapses & Mode Errors
• Lapses – failure to carry out an action
• Error of Omission (working memory)
• Examples: Forgetting to close gas cap, failure to put
safety on before cleaning gun, failure to remove objects
from surgical patient
• Mode Errors – Making the right response, but while
in the wrong mode of operation
• Examples: leave keyboard in shift mode while trying to
type a numeral, driving in wrong gear, going wrong
direction because display was north-up when thought it
was nose-up
Human Reliability Analysis
• Human Reliability Analysis – predict reliability of
system in terms of probability of failure or mean time
between failures (MTBF) when system is designed to work
in parallel or series
Parallel
Series
.9
.9 .9
.9
Reliability = .9 x .9 = .81 Reliability = 1 – [(1 - .9) (1 - .9)]
P(failure) = 1 - .81 = .19 = 1 - .01 = .99
(see homework) (HW answers) P(failure) = 1 - .99 = .01
Technique for Human Error Rate Prediction
(THERP)
THERP components
1. Human Error Probability
• Ratio of errors made to possible errors
2. Event Tree
• Diagram showing sequence of events
• Probability of success or failure for each component
3. Other Moderating Factors
• May add in multiplier to account for variables such as experience
level, time, stress, etc.
Error Prevention / Remediation
1. Task Design – design tasks with working memory
capacity in mind
2. Equipment Design
a) Minimize perceptual confusions – ease of
discrimination
• Ex: airplane controls that feel like what they do (flaps, wheels)
b) Make consequences of action visible – immediate
feedback
• Ex: preview window in some software programs
c) Lockouts – design to prevent wrong actions
• Ex: car that will not let you lock door from outside without key
d) Reminders – compensate for memory failures
• Ex: ATM reminds you to take your card
Error Prevention / Remediation (continued)
3. Training – provide opportunity for mistakes in
training, so can learn from them
• Ex: Simulation
4. Assists and Rules – checklists to follow
• Ex: Pilot pre-flight checklist
5. Error-tolerant systems – system allows for error
correction or takes over when operator makes
serious error
• Ex: Undo button
Approaches to Hazard Control
• Optimization standpoint - the most critical or
“high-risk” hazards should receive top priority
• e.g. MIL-STD-882B categories of hazard (matrix combines
frequency and severity categories)
Severity
Frequency Catastrophic Critical Marginal Negligible
Frequent 1 3 7 13
Probable 2 5 9 16
Occasional 4 6 11 18
Remote 8 10 14 19
Improbable 12 15 17 20
1 = Highest priority, 20 = Lowest priority
Hazard Control Priority
Reduce Hazards by:
1. Source – designing out a hazard
• Baby items too large to swallow
2. Path – barrier or safeguard
• Guard on back of lawnmower to protect toes
3. Person – change behavior with training or warnings
• Warning: fan blades can turn on while engine is off
4. Administrative controls – rules mandating behavior
• Must wear safety belts
Safety Analysis
Sequence for identifying potential hazards and
recommendations for hazard reduction: (Weinstein et al. 1978)
1. Task Analysis – How will product be used?
2. Environment Analysis – Where will product be used?
3. User Analysis – Who will use product?
4. Hazard Identification – What is likelihood of hazard with product?
5. Generate Methods for Hazard Control – What might eliminate
hazards?
6. Evaluate Alternatives – How will alternative designs affect product
performance?
7. Select Hazard Control – Given alternatives, what is best design to
minimize hazards?
Hazard Identification
Methods for identifying potential hazards:
• Preliminary Hazards Analysis
• simplest method
• Development of a list of the most obvious hazards
• Failure Modes and Effects Criticality Analysis (FMECA)
• Breaking down of physical system into subassemblies
• Each subassembly is broken down further and each component is
analyzed
• Effect of each component’s failure on other components is estimated
• Fault Tree Analysis
• Top-down process
• Works from incident to possible causes
Accident Investigation
Fact-Finding (OSHA recommendations)
• Interview witnesses as soon after accident as possible
• Inspect accident site before changes occur
• Take photos/sketches of scene
• Record all pertinent data on maps
• Get copies of all reports
• Obtain documents containing normal operating procedures/
maintenance charts, reported abnormalities
• Keep complete accurate notes in bound notebook
• Record pre-accident conditions, accident sequence,
post-accident conditions
• Document location of victims, witnesses, machinery, energy
sources, and hazardous materials
Accident Investigation
Levels of Causes
Management Safety Policy & Decisions
BASIC Personal Factors
CAUSES Environmental factors

INDIRECT
Unsafe Act Unsafe
CAUSES Condition
(SYMPTOMS)

DIRECT Unplanned Release of Energy

And/or
CAUSES
Hazardous Material

ACCIDENT
Personal Injury
Property Damage
Safety Programs
1. Identify risks to the company
▪ identify hazards, hazard controls, accident frequency, & company losses
due to accidents/incident claims
2. Implement safety programs, includes:
▪ management involvement, accident investigation, recommendations for
equipment, safety rules, personal protective equipment, employee training,
safety promotion
3. Measuring program effectiveness
▪ evaluated by assessing changes in safety behaviors, accident/incident
rates, number of injuries or death, and number of days off due to injury
Risk-Taking and Warnings

• Risk-Taking as a Decision Process

• People must know a hazard exists, know what
actions are available, & know the consequences of
the safe behavior vs. alternative behaviors
• Written Warnings and Warning Labels
• Accurately convey the hazards of a product
• Should include a signal word, info pertaining to the
hazard, consequences, & necessary behavior
• Danger: Immediate hazard likely results in severe injury
• Warning: Hazard could result in injury
• Caution: Hazard or unsafe use my result in minor injury
Performance appraisal (Merit Rating)
• Merit Rating assesses the merit of the person doing the job. Merit
rating determines the extent to which an employee meets job
requirements. Job evaluation and Merit Rating are two
complementary aspects of a sound personnel policy.
• The first, determines a suitable wage structure for the job and the
second (i.e., merit rating), decides the rewards an employee should
get in addition to his wages, depending upon his merits.
• Merit Rating is a systematic and orderly approach to assess the
relative worth of an employee working in an organisation in terms of
his job performance, integrity, leadership, intelligence, behaviour, etc.
• Merit rating is commonly referred to as Employee Rating, Employee
Appraisal or Staff Reporting.
Objectives of Merit Rating
• (1) Merit rating provides a record of the worth of employees;
they, therefore, can be put on the most appropriate jobs
depending upon their capabilities.
• (2) Merit rating unfolds the limitations of an employee and thus
helps in employee improvement.
• (3) Merit rating records form a basis for:
• (a) Wage-increase, (b) Promotion, (c) Special assignments,
• (d) Training, (e) Transfer, and (f) Discharge.
Methods of Merit Rating
• 1. Rating Scale Method:
• The steps involved in Rating Scale method are:
• (a) Define the merit factors (i.e., standards) to rate the employees.
• The different factors, according to the nature of job may be as
follows:
• i. Standard of output, ii. Quantity of output, iii. Intelligence, iv. Job
knowledge, v. Leadership, vi. Integrity, vii. Dependability, viii.
Education and experience, ix. Efforts and initiative, x. Adaptability, xi.
Co-operation, xii. Judgment, xiii. Character, xiv. Loyalty,
Methods of Merit Rating
• Check List Method
• The method employs a list of questions and several statements
which are concerned with the employee performance on various
aspects of the job and which are considered important for
evaluating the merit of an employee for that job. The questions
are of Yes or No type. Each question or statement possesses
certain points which when totaled together for all the relevant
questions indicate the rating of an employee.
• Employee Comparison Method
• The method compares a worker on a job with all other workers
on the same job, in pairs.
Incentive plans
The various incentive plans can be classified into two groups:
1. Individual Incentive Plans
2. Group Incentive Plans.
• 1. Individual Incentive Plans:
Under individual incentive plan, individual employee is paid incentive on the
basis of individual performance or output. The employers are liable to pay
incentives to those employees who are producing more than the standard output.
Individual incentive plans can be either time based or production based.
• Advantages:

• a. This system checks over-speeding and overstrain by worker.

• b. Each worker is guaranteed a minimum wage.
• c. Efficiency is rewarded.

• Disadvantages:
• a. The workers find it difficult to understand.
• b. Discourages workers to over-achieve.
• c. Workers may not like sharing of profit for over-achievement.
• Some of the time based incentive plans are:

• I. Halsey Incentive Plan.

• II. Rowan Incentive Plan.
• III. Emerson Efficiency Plan.

• Some of the production based incentive plans are:

• I. Taylor’s differential piece rate system.

• II. Merrick’s multiple piece rate plan.
• III. Gantt’s task and bonus wage plane
I. Halsey Incentive Plan:
• In this method a standard time is fixed for the completion of the job. A minimum
base-wage is guaranteed to every worker. If a worker completes his job in just the
standard time, he will not be given any incentive. If a worker performs his job in less
than standard time, he is given incentive. The incentive will be equal to 50% of the
time saved by the worker.
• W=TR+(S-T)
Where
• W=Total Wages
• S=Standard time
• T=Time taken to complete the job
• %=Percentage of wages of time saved to be given as incentive
• R=Rate;
Advantages & Disadvantages:
• Advantages:
• a. It is simple.
• b. Each worker is guaranteed a minimum wage.
• c. This is beneficial to efficient worker.
• d. Causes no harm to new worker, trainee, or slow workers.
• Disadvantages:
• a. Workers get only a percentage of return on their over-achievement.
• b. The quality of production may suffer as workers may do work in hurry,
• c. There may be difficulties in setting standard time for different jobs.
 II. Rowan Plan:
• This plan is quite similar to Halsey plan. It differs only in terms of calculation of
incentive for time saved. The worker gets the guaranteed minimum wages. The
incentive for completing the job in time lesser than standard time is paid on the basis
of a ratio, which is time saved over standard time per unit standard time.

• Incentive is calculated as:

• Incentive or Bonus=S-1/SX T x R
• Total wages=T x R+ incentive
• =T x R(S-T)/S x T x R
• Where, W=Total wages
• S=Standard time
• T=Time taken to complete the job
• R=Rate.

• For example, if rate per hour is Rs.3and standard time for completion of job is 10
hours.
• A worker completes the job in 8 hours, his total wages will be:
• W=8×3+ (10-8)/10x 8x 3=
• ANS=Rs.28.4
III. Emerson’s Efficiency Plan

• In this plan, a minimum wage is guaranteed to every worker on time basis

and incentive is given on the basis of efficiency. Efficiency is determined by
the ratio of time taken to standard time. Payment of bonus/incentive is
related to efficiency of the workers. Incentive will be given to those workers
who attains more than 2/3rd i.e. 66.67% of efficiency. No incentive will be
given at 66.67% efficiency. At 100% efficiency incentive is 20% of the
hourly rate. For efficiency exceeding 100%, 1% incentive/bonus is paid for
every 1% increase in efficiency.
 Output-Based Plans:
• I. Taylor’s Differential Piece Rate System:

• This system was introduced by Taylor, the father of scientific management. The main
characteristics of this system are that two rates of wage one lower and one higher are
fixed. A lower rate for those workers who are not able to attain the standard output
within the standard time; and a higher rate for those who are in a position to produce
the standard output within or less than the standard time.
• For example, if standard production in 8 hours is fixed at 10 units. The lower
piece rate is Rs.3 and higher piece rate is Rs.3.5. If a worker produces 9 units,
his wages = 9 x 3 = Rs.27. In case a worker produces 10 units, his wages = 10 x
3.5 = Rs.35.
• Advantages:
• a. Provides incentives to efficient worker.
• b. Inefficient worker is penalized.
• c. This system is simple and easy to implement.
• Disadvantages:
• a. Minimum wage is not assured,
• b. There are chances that quality of work may suffer,
• c. This system is not liked by below average workers, as they do not get any incentive
II. Merrick’s Multiple Piece Rate Plan:
• To overcome the limitations of Taylor’s differential piece rate system, Merrick
suggested a modified plan in which, three-piece rates are applied for workers with
different levels of performance.
• These are:
• a. Workers producing less than 83% of the standard output are paid at basic rate.
• b. Workers producing between 83% and 100% of standard output will be paid 110% of
basic piece rate.
• c. Those producing more than 100% of the standard output will be paid 120% of basic
piece rate.
• Advantages:
• a. Efficient workers are rewarded handsomely.
• b. Minimum wages are guaranteed.
• Disadvantages:
• a. There is wide gap in slabs of differential wage rate.
• b. Over emphasis on high production rate.
WHAT IS KRA (Key Result Areas)?
• KRAs or Key Result Areas are the mail objectives for which you
perform your task or role in the organization. It is generally the
purpose of your role and not a list of your daily activities on the
job and has a border perspective of performance with standards
of achievements.
• KRAs capture about 80% to 90% of a work role. The remainder
of the role is usually devoted to areas of shared activities. (E.g.
helping team members, participating in the activities for the
good of the organization)
KRA (Key Result Areas)
• Once KRA has been decided and agreed upon with your supervisor it
gives you the following advantages:
• Clarity on expectation from the job.
• To improve focus and hence Performance.
• Helps develop Skills, Ability and Knowledge.
• Provide a sense of achievement
• Helps manage time effectively and balance your life.
• Helps in performance appraisal discussion and career progression
• In communicating their roles and purposes to others
Ergonomics
• Ergonomics is the scientific study of how people interact
effectively with products, equipment, facilities, procedures and
environments used at work and in everyday living.
• Ergonomics seeks to match the design of machines, jobs and
workplaces with the capabilities, limitations and needs of people.
• Ergonomics seeks to maximize ease of use and optimize
operator productivity, comfort and health.
Ergonomics definition
by the International Ergonomics Association (IEA) Executive
Council

Ergonomics (or human factors) is the scientific discipline concerned

with the understanding of the interactions among human
and other elements of a system, and the profession that applies
theory, principles, data and methods to design in order to
optimize human well-being and overall system
performance.
Ergonomics is fitting the work to the
worker
in order to reduce risk of injury/discomfort
Ergonomics is about “fit”. The fit
between a person and what they do, the
objects they use and the environments
in which they work. If good fit is
achieved, the stresses on people are
reduced. They become comfortable,
Exposure to more
can do things efficiently and
than one risk factor
productively without discomfort.
increases the
chances of
An ergonomic evaluator will look for
experiencing
specific risk factors that may indicate a
discomfort.
“poor” fit, and then make
recommendations to reduce these risks
 •Introduction to computer-aided
ergonomic analysis of workstation
Introduction to computer-aided ergonomic
analysis of workstation
• The summary picture does give you an idea of what an
ergonomic seating position looks like, though. How close is this
to the way you're sitting right now?
Introduction to computer-aided ergonomic
analysis of workstation
• A good computer work station requires a decent computer desk
and chair that provide the required adjustability to achieve an
ergonomically correct computer workstation. Beyond the chair,
there is a need to potentially adjust the height of desk and your
monitor, too.
Introduction to computer-aided ergonomic
analysis of workstation
• 1. The top of your monitor should be at eye level, and directly
centered in front of you. It should be about an arm's length in
front of you.
Introduction to computer-aided ergonomic
analysis of workstation
• 2. Your desk surface should be at roughly belly button,
level. When your arms are placed on the desk, your elbows
should be at a —90 degree angle, just below the desk surface.
The armrests of your chair should be at nearly the same level
as the desk surface to support your elbows.
Introduction to computer-aided ergonomic
analysis of workstation
• 3. Your feet should be flat on the floor with your knees at a
—90 degree angle. Your seat should not be pressing into the
back of your knees; if necessary, tilt it slightly forward to
alleviate any knee pressure. Sit fully back in your chair, with
your back and shoulders straight and supported by the back of
the chair.
Introduction to computer-aided ergonomic
analysis of workstation
• 4. When typing, your wrists should be in line with your
forearms and not bent up, down, or to the side. Your
keyboard should be directly centered in front of you. Other
frequently used items should be nearby, within arm's reach.
Repetition

Clawing the fingers increases muscle tension in the forearm

Use the autoscroll feature, the up or down arrows or the end and
home keys on the keyboard
Awkward and Sustained Posture
Awkward postures that are sustained over periods of time can cause muscle tension, reduce blood flow and
even pinch nerves. Maintaining a more neutral posture over time can help reduce discomfort

Extended forward Bending forward at the Shoulders shrugged

reach to keyboard and waist during sitting. upward This is happens
mouse. Reaching forward This happens when feet are when the keyboard and
can cause muscle tension not supported and puts mouse is too tall for the user.
between the shoulder pressure on the lumbar
blades and the neck, discs.
especially when this posture
is sustained over time. Why
Contact Stress
Contact stress is pressure on the body by a hard edge/surface. This can reduce circulation
and obstruct nerve signals leading to swelling, tingling or discomfort.

Hard desk edge against forearm. Front edge of seat against calf.
Computer user discomfort reports

Discomfort Commonly caused by

Headache Monitor height not ideal
Midback tension Extended reach to keyboard/mouse
Shoulder tension Keyboard and mouse too high
Forearm/elbow Clawing of the scroll wheel
Wrist Awkward posture during typing
Low back Unsupported feet or chair not adjusted to fit
What is a musculoskeletal disorder?
A musculoskeletal disorder
is discomfort that
accumulates over time in
the muscles, ligaments,
tendons, joints or nerves
which could include strain,
sprain, or inflammation.
Musculoskeletal discomfort can occur anywhere in the body and typically are not
caused by a single traumatic event, but is due to micro trauma to tissues that
does not heal during rest.
Musculoskeletal disorders can be controlled
through ergonomics

Why is
ergonomics
important?
Exposure to an
ergonomic risk
factor increases
the likelihood that
you will
experience
discomfort.
There are many ways people position
themselves to use their computer
So let’s learn the ideal way….
 Four areas of focus
Guidelines on how
to ideally adjust 4
your workstation to
fit you will focus on Eyes to screen
four areas. These
will be reviewed Hands to mouse
one at a time. and keyboard
These steps will
1
guide you through 3 Body to chair
the adjustments
you need making
them personal to
you. The goal is to
help you find the
position in which
you can work
comfortably

2
Feet to floor
 Body to chair
The first point of
focus is body to
chair. This
considers how
your workstation
seating affects
your back,
shoulders, hips
and upper legs.
This section
reviews the key
chair adjustments
including seat
height, seat
depth, backrest
support and
armrests.
Click on the picture of your chair
to open adjustment instructions.

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Chair adjustment sequence
Please follow these in order

1. Move your chair away from your desk.

2. Adjust the seat height so that your feet feel
comfortable on the floor.
3. Adjust the seat depth so that you have 2-3
finger width between the front edge of the chair
and your calf.
4. Raise/lower the lumbar support to fit in the
curve of your back. You will either adjust the
entire backrest or just the lumbar within the
backrest.
5. Backrest tilt and tension. Adjust the backrest
tilt to your comfort and adjust the tension that it
takes to recline or remain more upright via
knob.
6. Adjust the armrests:
a. Lower one armrest completely.
b. Bend that elbow to 90 degrees.
c. Raise that armrest to hold the forearm
in the 90 degree position, without
pushing the shoulders up.
Now that your chair is ideally adjusted
move your chair back to your desk
You will find the following….click the gray bar description of what matches your situation
The armrest you adjusted is:

At the same height as your desk/keyboard

tray

Lower than your desk/keyboard tray

Higher than your desk/keyboard tray

The armrest you adjusted is:
At the same height as your desk or
keyboard tray

Congratulations, your chair and input

devices(keyboard and mouse) are at your
ideal sitting worksurface height.
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The armrest you adjusted is:
Lower than your desk/keyboard tray

If using a keyboard tray: If not using a keyboard tray:

Lower the height of the Raise the seat height up
keyboard tray to be so that the armrest is
level with the desktop.
level with the armrest Then be sure to support
you adjusted. This will your feet. If your chair
bring your keyboard will not go high enough,
and mouse down to this means you NEED A
your ideal sitting work KEYBOARD TRAY.
surface height.
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The armrest you adjusted is:
Higher than your desk/keyboard tray

If using a keyboard tray: If not using a keyboard tray

Raise the height of the keyboard Lower the seat height so
tray to be level with the armrest that the armrest is level
you adjusted. This will bring with the desktop.
your keyboard and mouse down
to your ideal sitting work surface
height.

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 Feet to floor

The second
area of focus
is feet to floor.
This considers
how
equipment at
your
workstation
affects the
position of Kno
your lower w
legs, ankles
If your feet are unsupported…

1. Lower your chair seat height

then
O Use a footrest. Many are
styles are available
2. Lower your keyboard/mouse
height R
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 Unsupported feet can cause back pain!
If your feet are not planted firmly on the floor, it is
recommended that you use a footrest.

With
Center of gravity
unsupported
has moved
feet, the user
forward. To
may “slouch
maintain balance,
sit” which puts
feet are on rungs
significant
of chair and the
pressure on
user leans
the low back.
forward.

Without ideal support for your feet, your body will adjust itself and this
may lead to lower back discomfort. Why
 Hands to mouse and keyboard
Hands to
keyboard and
mouse focuses
on how
equipment in
your
workstation
affects the
posture of your
hands, wrists,
arms and
shoulders. This
section will
review how to
best position
the keyboard
and mouse.
Height
Keyboard and mouse should be located on the same level and
elbows should be 90 degrees
Keyboard and mouse just right

Armrests allow relaxed shoulders and the keyboard and mouse are close to the
user
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Keeping it Neutral
Do: Keep wrists flat Don’t: Angle wrists back

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Do I need a wristrest?

Wrist resting and putting Wrist free. Meaty part of the hand
pressure on the nerve resting with no pressure on the
nerve.
This is a PALM SUPPORT
Studies have shown an increase in pressures within the carpal canal when
keyboarding with anchored wrists. There should be no pressure on the wrists,
ever, including watchbands, hair ties, or rubberbands. If you learned to type with
anchored wrists, then use of a palm support may reduce your risk

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Do I need an ergonomic keyboard?
Ergonomic keyboards do one thing: Prevent ulnar
deviation

There are many alternative keyboards on the market. Not everything that is marketed
as ergonomic really is.
The purpose of an ergonomic keyboard is to eliminate awkward bending of the wrists,
primarily on the right. Not everyone will need an ergonomic keyboard, only those
demonstrating this wrist position.
Other alternative keyboards eliminate the number pad, thereby allowing the mouse to
sit closer to the user on the right. Why
Do I need an “ergonomic” mouse
There are even more alternative mice
on the market than there are
alternative keyboards.
Manufacturers have a monetary
interest in telling you how bad your
current mouse is and how much better
their expensive mouse will make you
feel.
Buyer beware.
A trained professional is the best
person to help determine if an
“alternative” mouse is right for you. Kno
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 Eyes to screen

This considers
the aspects of
your
workstation
that effect
your vision.
This section
will review the
position of
your monitor/s
and the ideal
height for you.

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Single monitor
Position

Your monitor should sit directly in front of you. The

center of the monitor should be in line with your
body.
D
Laptop Only
Position
To maintain hands to
keyboard and mouse
Use peripheral keyboard and
mouse

To maintain eyes to
monitor/screen:
Raise laptop screen

D
Laptop only

Head up, but arms up Arms down, but Head up and

causing shoulder pain head down causing arms lower, now
and overreach neck and upper resting on table
back tension cutting circulation
off to hands
No Ideal position for long term use of laptop. If at all
possible, limit duration of use to 1 hour or less
Why
Common monitor positioning mistakes
Avoid placing laptop in front
Avoid placing monitors in front of of freestanding monitor
windows

Your pupil will constrict to the Your neck must still

brightest light in the room and if bend too far to view the
the monitor is facing a window, laptop in this position.
your eye will work harder to see
Why
the monitor.
Ideal monitor height
Non bifocal user Bifocal user

The top 1-2” of the computer monitor is The top of the computer monitor is
LEVEL with the eye. This allows the LOWER than the eye, due to
eye to have a 15-30 degree downward placement of the lenses in the glasses
gaze which is ideal. for that distance. This allows the eye to
have a 15-30 degree downward gaze
which is ideal. D
Common monitor height mistakes
Bifocal user
Non bifocal user

Monitor is positioned in the middle Bifocal user must tip head

of her forward gaze. This will back to see the monitor
cause significant eye strain over that is placed too high.
time.

Why
•Assessment of postures and
identification of risks to body
regions.
Physical Ergonomics and Work
Related Musculoskeletal Disorder
(WRMSD)
Physical Ergonomics is concerned with human anatomy,
anthropometry, physiology and bio mechanical characteristics as
they relate to physical activity in work or daily life.

Certain jobs or work conditions cause a higher rate worker complaints

of undue strain, localized fatigue, discomfort, or pain that does not go
away after overnight rest.

Every year 1.8 million U.S. workers experience WRMSDs and nearly
600,000 of the injuries are serious enough to cause workers to miss
work.
Ergonomic risk factors common in the office
Click on each to learn more.

Awkward posture
Sustained posture

Repetition Discomfor Contact

t Stress

Musculoskeletal Disorder
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 Rapid Upper Limb Assessment (RULA)
• Rapid Upper Limb Assessment (RULA) method was designed to analyze the
biomechanical/postural stresses on worker‟s Upper limbs and to identify the muscular
effort associated with a work posture. The RULA ergonomic assessment tool is in
conformity with the European directive 90/270/EEC.
• RULA uses a systematic process to evaluate required postures related to work cycle,
muscle use frequency and forceful exertions.
• The RULA assessment requires the determination of joint angles of different body parts
(shoulder, elbow, wrist, trunk and neck). This method was developed to investigate the
exposure to the individual risk factors assicoted with Musculoskeletal disorders (MSDs).
Validated by several studies, RULA method is used by many ergonomists around the
world.
 Rapid Upper Limb Assessment (RULA)
• The Rapid Upper Limb Assessment (RULA) (RULA) is an ergonomics based workplace risk
assessment tool that allows you to calculate the risk of musculoskeletal loading within the upper
limbs and neck. RULA is easy and quick to use and and does require expensive equipment to
complete.
• RULA is designed to be a rapid tool.
• The published toolis validated and has been tested by McAtamney and Corlett and
many others as reliable.
• The final score is a relative score of risk not an absolute score of risk.
• RULA is intended to be part of a broader ergonomics survey.
• RULA is a screening tool that assesses biomechanical and postural loading on the whole body
with particular attention to the neck, trunk and upper limbs.
• A RULA assessment requires little time to complete and the scores generated fit into an action
list which indicates the level of intervention required.
• RULA‟s useful scoring system allows you to take a snapshot of the highest risk posture adopted
during the task. The scoring system is broken down into four actions levels with indications in as
to the urgency of the investigation.