Ergonomics
Eng. Anil Ranasinghe
What is Ergonomics?
“Ergonomics is an applied science concerned with
the design of workplaces, tools, and tasks that
match the physiological, anatomical, and
psychological characteristics and capabilities of
the worker.” Vern Putz-Anderson
“The Goal of ergonomics is to ‘fit the job to the
person,’ rather than making the person fit the job.”
Ergotech
“If it hurts when you are doing something, don’t do
it.” Bill Black
Ergonomics....
is the science and practice of designing jobs and
workplaces to match the capabilities and limitations of the
human body.
Ergonomics means “fitting the job to the worker”
is making sure that the demands of the job do not go
beyond what a worker can do safely
Goal of Ergonomics
Is to create jobs, tools,
equipments and workplace that
fit people rather than make
people adopt to fit them
Evolution of Ergonomics
Dates back to Bernardino Ramazzini 1700’s (Father
of Occupational Medicine)
Gained significance during WWII for airplane cockpit
layout
Progressed slowly until the 80’s and 90’s with the
advent of the computer and more efficient workplace
design
Now, guidelines are in place and greater use of
technology
Why ergonomics is important?
Dramatic increase of reported MSD’s.
Poor machine design.
Increased task requirements.
Increased work hours.
Increases in production.
Specialized work tasks.
Repetition of Work tasks.
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The places where Ergonomics is
Important
At factories & Industries
At offices
Sports
Leisure activities
Domestic work
Education and training
Health and social services
Public places…….
PROFESSIONS HAVING
COMPLEMENTARY ROLES WITH
ERGONOMICS
Safety Civil
Occupational Officer Engineer
Health Officer
Mechanical
Industrial Engineer
Nurse ERGONOMICS
Architect
Physiotherapist
Industrial
Ind. Medical
Social Designer
Officer
Psychologist
ERGONOMIC FOCUS
The Task
The Tool
The User /Operator
The Work
Station and
Environment
APPROCH OF ERGONOMICS
improving working conditions and reducing
illness at work
attempts to ‘Fit the Job to the Man’ rather
than ‘Fit the Man to the Job’
concerned with the design of systems in
which people carry out work
optimizes Efficiency, Health, Safety and
Comfort of people through better designs of
products and work places
Benefits of Ergonomics
Ergonomics helps to prevent injuries (safety)
Ergonomics has other benefits
Improved quality of work
Improved quality of life
Reduced fatigue and discomfort
Improved Product quality
Improved Efficiency
Improved job satisfaction
Improved personal health
Decreased lost work days
Decreased labor turnover & absenteeism
Multidisciplinary
Nature of Ergonomics
• Anatomy and Physiology
• Engineering Psychology
• Engineering
• Medicine
• Anthropology
• Biomechanics
Types of Problems or Mismatches
Physical Size
Endurance
Strength
Manipulative
Environmental
Cognitive
Physical Size
Clearance
Reach
Equipment Size
Personal Protective
Equipment (PPE)
Endurance (Capacity for Work)
Environmental
• Noise
• Lighting
• Thermal
• Chemical
Cognitive
• Machine Pacing
• Shift Work
• Morale
• Psychosocial
Strength
• Force Requirements
• Male/Female
• Manual Materials Handling
Other Issues
• Aging workforce
• Universal design
Ergonomic needs in a workplace
Physical work environment
Thermal comfort
Noise and vibration control
Adequate and proper lighting
Chemical environment
Control of pollution
General and exhaust ventilation
Work physiology
Control excessive physical load
Avoid physical and muscular fatigue
Adequate rest pauses
Arrangement of static and dynamic work
Ergonomic needs in a workplace (Contd.)
Anthropometry (Body sizes)
Designs to fit body sizes of users
Appropriate working levels
Adequate work space
Avoid overcrowding of machines and workers
Occupational Biomechanics
Appropriate work postures (sitting, standing)
Safe load lifting and carrying techniques
Adopt proper techniques in manual materials
handling
Ergonomic needs in a workplace
Psychological aspects
Avoid perceptual and mental loads and fatigue
Appropriate design of displays and control
Appropriate conditions for Vigilance tasks
Avoid human error and stress
Job motivation and satisfaction
Social psychology
Practice good relationship among employees and
between employer and employee
Ergonomic needs in a workplace
Macro ergonomics
Suitable working hours , intervals, holidays, leave
Appropriate shift schedules
Welfare facilities
Job rotation and incentives schemes
Fair salary structure, Good administrative structure
Good work organization schemes
Fringe benefits (housing, transport, sports)
Labour union facilities
Training and education
Promotional prospects
Ergonomic needs in a workplace
Safety and Ergonomics
Good housekeeping
Performance feedback
Systems ergonomics
Systems groups in problem solving and development
work
Participative ergonomics
User centered designs
Injuries and risk factors
What are Work-related Musculo-Skeletal Disorders
(WMSDs)?
Common types and symptoms of injury
Causes and prevention of injury
Ergonomic related injuries
Work-related Musculo-Skeletal Disorders (WMSDs)
CTD’s (cumulative trauma disorders)
RSI’s (repetitive stress injuries)
RMI’s (repetitive motion injuries)
MSD’s can affect muscles, tendons, nerves, joints and
spinal disks.
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Risk factors and causes of MSD’s
Hand Intensive Work
Psycho Social Heavy, Frequent, or Awkward lifting
Excessive force during exertion
Excessive repetition
Awkward postures
Pushing, Pulling or Carrying Loads
Static postures
Quick motions
Compression or contact stress
Inadequate recovery times
Temperature Extremes
Vibration 27 6/29/2017
SYMPTOMS OF MSD
Muscle fatigue (discomfort) Decreased range of
pain (musles, joints) motion
Aching Loss of function
Burning Deformity
Numbness Cramping
Stiffness , loss of flexibility Decreased grip strength
Tingling Loss of balance
Change in color Swelling
Redness
WMSDs
WMSDs are occupational
disorders of the soft tissues:
• muscles
• tendons
• ligaments
• joints
• blood vessels
• nerves
Risk Factors
Risk of injury depends upon:
Duration of exposure
Frequency of exposure
Intensity of exposure
Combinations of risk factors
Duration
Duration – You usually need hours of exposure
before risk factors become a concern
Exposure can be all at one time or cumulative
over the day
Frequency
Frequency is often a concern in:
assembly tasks
sorting tasks
loading or off-loading materials
inventorying products
product stocking
software programming
telemarketing
customer service
Intensity
Intensity refers to:
weight in pounds of items lifted or carried
grip or pinch force of lifted or manipulated items
vibration level (meters/second2)
force on keys when typing
Combinations of risk factors
Exposure to more than one risk factor at a time greatly
increases the risk of injury.
For example:
Bending and twisting while lifting
Repetitive, forceful use of the hands with the wrists bent
Risk factors for WMSDs
Heavy, frequent or
awkward lifting
Alternatives to lifting
• Use carts, hand trucks, hoists, conveyors or
other mechanical assistance
• Slide objects instead of lifting them
• Store heavy items where you won’t have to
bend or reach to lift them
• Use ladders to get items down from high
shelves
Risk factors for WMSDs
Awkward postures
Neutral Posture –
The opposite of awkward posture
Standing neutral posture Seated neutral posture
Awkward postures
happen when the work is:
Too high
Too low
Too far away
Reducing low work
Raise and/or tilt the work for
better access
Use a stool for ground level work
Use tools with longer handles
Alternate between bending,
kneeling, sitting, and squatting
Reducing high work
Use an elevated work platform or rolling stairs
Use tools with longer handles
Limit overhead storage to infrequently used items
Bring the work down and tilt for easier access
Reducing Reaching
Keep items within close reach
(design reach distance for the shortest worker)
Remove obstacles
Use gravity feed racks
Risk factors for WMSDs
Hand Intensive Work
Hand Intensive Work
Repetitive motions Gripping
Bent wrists
Pinching
Reducing repetition
Arrange work to avoid unnecessary motions
Let power tools and machinery do the work
Spread repetitive work out during the day
Take stretch pauses
Rotate task with co-workers if possible
Change hands or motions frequently
Hand Intensive Work – Gripping and Pinching
A power grip is 5 times
stronger than a pinch grip
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Other factors
Your grip strength decreases
when you:
• Bend your wrists
• Pick up slippery items
• Wear poorly fitting gloves
• Have cold hands
Reduce grip force
Grip with the whole hand, not just the fingertips
Pick up smaller loads
Use carts or handtrucks instead of carrying
Keep tools in good working order
Use lighter tools or tool balancers
Use two hands
Keep your wrists straight
Avoid pinch grips
Pick objects up from the bottom using whole hand
Attach handles or use lift tools
Build up handles on small tools to reduce grip
force
Avoid holding onto objects for long
periods
Use clamps to hold onto work
Place items on carts rather than carrying them
Put down a tool when not actually using it
Tool use example
Use tools that
Working with let you keep
bent wrists your wrist
decreases grip straight
strength
Hand Intensive Work – Combinations
Repetition +
Gripping or Pinching +
Risk of injury goes up as Bent wrists
you combine factors
Repetition +
Gripping or Pinching
Repetition
Risk factors for WMSDs
Vibration
Vibration
Exposure to vibration can occur while
using power tools or while driving
equipment.
Vibration from power tools can place
stress on the tissues of the fingers, hand
and arms.
Whole body vibration from driving puts
stress on the spinal tissues.
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Reducing vibration
Use low vibration tools if
available
Maintain tools
Use anti-vibration gloves
or tool wraps
Keep hands warm
Risk factors for WMSDs
Temperature Impact
Temperature Extremes
Environmental conditions such as
extreme heat or cold can place stress
on tissues.
Extreme cold constricts blood vessels
and reduces sensitivity and
coordination of body parts.
Excessive heat can result in increased
fatigue and heat stress.
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Risk factors for WMSDs
Repeated impacts
Repetition
Occurs when the same or similar movements
are performed frequently.
Repetition can also occur when different tasks
are performed if those tasks have the same
movements.
Injury may result from repetition when the
tissues do not have adequate time to recover.
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Industrial Ergonomics
By applying ergonomic principles in industrial
settings, a safer, healthier and more
productive work environment can be
developed
Employees and employers need to know how
to minimize risk factors by choosing the best
tools and work techniques for a given task.
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Industrial Ergonomics
Adjusting the Workstation
Adjust the Chair.
Adjust reach requirements.
Adjust focal requirements.
Place equipment and materials where appropriate.
Correct the Environment
Check lighting, noise and temperature.
Check work pace and stress levels.
Check work processes
Industrial Ergonomics
Choose the appropriate tools
Check the fit.
Make sure the tools match the task.
Improve work techniques and habits
Improve postures.
Check work techniques.
Improve Posture and Habits
Modify wrist/hand motions
Improve neck and back postures
Consider personal preferences
Developing Controls
Types of Controls
Engineering
Administrative
Personal Equipment
Implementing Controls
Evaluating Control Effectiveness
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Types of Controls
Engineering
Preferred approach
Appropriate initial design of the work station or
work area.
Improving the design of the existing work area or
equipment.
Providing necessary equipment and accessories.
Adjusting the work station layout and equipment.
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Administrative controls
Work practices and policies
Changes in job rules and procedures
Scheduling
More rest breaks
Rotating workers and adjusting work pace
Training workers to recognize risk factors
Training on techniques for reducing stresses and
strains
Usually considered as temporary
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Personal Equipment
Wrist supports, back belts, vibration attenuation gloves
Must be evaluated to insure they don’t create a hazard
PPE acts as a barrier between a person and a hazard.
PPE is only appropriate in situations when engineering
or administrative controls cannot be implemented.
Back belts and other braces are not considered PPE.
These devices should not be used in place of incorrect
work techniques.
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Implementing Controls
Sources
Trade Associations
Insurance companies
Consultants
Visits to other sites
Training courses
Input for workers
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Implementing Controls
Process
Trials and tests of selected solutions
Modify or revise tested solutions
Full-scale implementation
Follow up and evaluation of effectiveness of
controls
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Evaluating Controls Effectiveness
Use the same risk factors checklist
Re-do job hazard analysis
May include a symptoms survey
Short term - 1-2 weeks after implementations of
solutions
If hazards are not substantially reduced or eliminate
re-start problem solving process
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Evaluating Control Effectiveness
Long term evaluations are necessary
Indicators of and effective program include:
Reduction in the incidence rate of MSD’s
Reduction in the severity rate of MSD’s
Increase in productivity or quality
Reduction in job turnover or absenteeism
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Setting the stage for action
Ergonomic as part of S&H
Reactive vs Proactive
Design phase
Avoid risk factors
Preplanning of tool and equipment selection to fit job to
worker
Workstation layout
Job design
Materials selection
Cost Effectiveness
Management Commitment
Must be a Company goal
Expect full cooperation
Assign lead roles
Management Commitment –cont.
Give ergonomics equal priority with:
Cost reduction
Productivity
Quality assurance
Work with and involve local unions
Resource commitment
Communication in both directions
Management evaluation of the program
Union and Worker Involvement
Promotes safety and health
Have a better understanding of the job
tasks
Adds problem solving capabilities
Ownership
Greater acceptance of changes
Improves job satisfaction
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Some important ergonomic requirements (From ILO Ergonomic Checkpoints)
Materials storage and handling
Clear and mark transport routes
Provide ramps of 5-8% inclination instead of
small stairs
Use mechanical devices for lifting, lowering
and moving heavy material
Instead of carrying heavy weights divide them
into smaller lightweights e.g. 2x10 kg instead
of 20 kg.
Combine heavy lifting with physically lighter
tasks
Some important ergonomic requirements (From ILO Ergonomic Checkpoints)
Hand Tools
Use hanging tools for operations repeated in
the same place
Provide hand support when using precision
tools
Provide hand tools with a grip of the proper
thickness (hand diameter 30-40 mm, handle
length 125 mm and size to fit male hands)
Provide a home for each tool (Enables good
housekeeping)
Some important ergonomic requirements (From ILO Ergonomic Checkpoints)
Production machine safety
Locate controls in sequence of operations
Make displays and signals easy to distinguish
and easy to read
Use properly fixed guards and interlock
devices
Some important ergonomic requirements (From ILO Ergonomic Checkpoints)
Improving workstation design
Adjust the working height around elbow level
Light work: at elbow level
Precision work: above elbow level
Hard work: below elbow level
Some important ergonomic requirements (From ILO Ergonomic Checkpoints)
Lighting
Increased use of daylight
Light up the work area evenly
Sufficient lighting for working
Local lighting for precision work
Removing shiny surfaces
Avoid glare
Some important ergonomic requirements (From ILO Ergonomic Checkpoints)
Premises
Prevent the exposure to excessive heat
Install effective local exhaust systems
Increase the use of natural ventilation
HOW CAN ERGONOMICS CONTRIBUTE TO TECHNOLOGY
DEVELOPMENT IN DEVELOPING COUNTRIES
By adaptation of technology of the west
By improving working conditions through
ergonomics interventions
By developing traditional methods
In acquiring modern technology
In modifying techniques
Need Training and Education in Ergonomics
Useful References
o Fundamentals of Industrial Hygiene, 3rd Edition.
National Safety Council Pgs. 283-334
o Industrial Hygiene Engineering, 2nd Edition. National
Institute for Occupational Safety and Health Pgs. 702-
765
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Useful References
o The Occupational Environmental – Its Evaluation and
Control, 2nd Edition, AIHA, Section 4, The Human
Environment at Work.
o Kodak’s Ergonomic Design for People at Work, 2nd Edition,
Chengalur, Rodgers and Bernard, 2004.
o Fitting the Task to the Human, 5th Edition, Kroemer &
Grandjean, 1997.
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Useful Internet Sites
www.ergonomics.ucla.edu
www.me.berkeley.edu/ergo/
www.uhs.berkeley.edu/facstaff/ergonomics/index.shtml
www.llnl.gov/ergo/welcome.html
www.busserv.ucsb.edu/irp/ergo/tsr.htm
ehs.ucsc.edu/safety/ergonomics.php
blink.ucsd.edu/Blink/External/Topics/Policy/0,1162,4008,00.html
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Useful Internet Sites
http://ergo.human.cornell.edu/
www.3m.com/cws/selfhelp/index.html
www.pc.ibm.com/ww/healthycomputing
www.dir.ca.gov/dosh/REU/REU_WhatsNew.html
www.osha.gov/SLTC/etools/computerworkstations/index.ht
ml
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