1. Ergonomics
A Zengeya
Factories and Works Inspectorate
NSSA- CHINHOYI
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2. INTRODUCTION
 ERGO = “WORK”
 NOMOS = “LAW”
 ERGONOMICS = “LAW OF WORK”
 ERGONOMICS = relationship between
man and his occupation, equipment and
environment, and particularly the
application of anatomical, physiological
and psychological knowledge to problems
arising there from.
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3. AGENDA
SCIENTIFIC TECHNOLOGICAL
ASPECTS ASPECTS
 Anatomy  Technological design
 Physiology  Workspace design
 Psychology  Environmental
 Work environment design
 Work situation
design
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4. Overview
The practical aims of ergonomics are
the efficiency and safety of man-
machine and man-environment
combinations, together with the
welfare and satisfaction of the people
involved.
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5. ANATOMY
 ANTHROPOMETRY;- The dimensions of the human
body with its variations
 BIOMECANICS:- This involves the forces which can
be applied by the body under varying conditions.
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6. BASIC ANTHROPOMETRIC
VARIABLES
These include among others:
 Forward reach
 Stature
 Eye height
 Elbow height
 Knee height
 Fore-arm hand length
 Hand length and breadth
 Foot length and breadth
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7. BIOMECHANICS
This requires the knowledge of gross anatomy, in
particular the locations of the main muscle
groups, their composition and modes of action.
Principles of effective application of forces
include among others:
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8. BIOMECHANICS CONT’D
Principles of effective application of forces include
among others:
 To try to get the body mass to exert the force rather than
the muscles
 To use the largest available muscles moving a joint
around the central region of its total range.
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9. PHYSIOLOGY
Work physiology:- is concerned with energy
production and expenditure when working
Environmental physiology:- deals with
effects of the physical environment of the
workplace. It provides measures of stress
and standards of what is reasonable.
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10. Factors that Influence Physiology
Intrinsic Factors
 Nutrients
 Metabolism
 Heart function
Extrinsic Factors
 Environmental parameters
 Workload
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11. WORK PHYSIOLOGY
 The effect of the application of effort is an
important factor in task setting.
 Knowledge of the fatigue results of applied
effort can ensure that demands will not be made
on the worker, which may give rise to excessive
fatigue with the likelihood of reduced productive
and safety performances.
 The fastest way to regulate muscular workload
entails designing work-rest regimen which take
into account the work load and the needs and
capacities of the individual worker.
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12. WORK PHYSIOLOGY CONT’D
The physiology of muscular work involves;
Dynamic Muscular Work:- Active
skeletal muscles contract and relax
rhythmically. Heart rate, blood pressure,
and oxygen extraction in the muscles
increases linearly in relation to working
intensity.
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13. WORK PHYSIOLOGY CONT’D
Static Muscular Work:-muscle
contraction does not produce visible
movement, as for example, in a limb. The
delivery of nutrients and oxygen to the
muscle and the removal of metabolic end-
products from the muscle are hampered.
Muscles become fatigued and blood
pressure rises.
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14. ENVIRONMENTAL
PHYSIOLOGY
The environmental parameters include among others:
 Lighting
 Noise
 Vibration
 Climate
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15. Effects Of Body Temperature On
Physiology
 Body temperatures below 36ºC will very likely result in;
increased metabolic rate, reduced mental alertness,
reduced decision making, drowsiness, fatigue, irritability,
loss of consciousness & death (hypothermia/frostbite).
 Low temperatures & increased wind speed increase risk
 If core body temperature is above 38ºC, there will be
increased metabolic rate, fatigue, nausea, dizziness,
lightheadedness, disorientation, confusion, irritability,
malaise, flu-like symptoms (hyperthermia/heat stroke)
 High temperatures & reduced wind speed increase risk
 In both cases there is a physiological strain on the body
due to need for heat generation/dissipation respectively.
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16. Effects Of Noise On Physiology
 Constriction of blood vessels ►increased heart
rate & increased blood pressure
 Reduction in gastric activity ► digestion
problems, increased production of adrenalin &
corticotrophine
 Dilation of pupils ► difficult to focus on fine
work for long durations
 Increased muscle tension/muscular contraction
 Poor balance & concentration
 Disruption of menstrual cycle; impotence
 Anxiety & stress
 Stomach & abdomen movement
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17. Effects of Vibration on Physiology
 Fatigue
 Variation of blood vessel pressure &
impaired circulation
 Reduced grip, strength and manual
dexterity as well as reduced sensation
 Gastrointestinal disturbances
 Disturbances of the urogenital tract
 Impaired vision & dizziness
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18. Effects Of Oxygen Deficiency
 Increased heart rate & depth of breathing
 Dizziness
 Headache
 Loss of consciousness/recollection
Locations include;
Vats, Silos, Mines, Manholes etc
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19. Effects of Radiation on Physiology
 Increased pulse due to ionizing radiation
 Excessive temperature rise due to radio
frequency energy (microwave &radar
units)
 Brain & bone marrow injury
 Startle reactions associated with spark
discharges and contact reactions
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20. PSYCHOLOGY
 Skill Psychology:-
involves the mental
activity of information
processing and
consequent decision
making
 Occupational
Psychology:- deals with
the training effort and
individual differences
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21. PSYCHOLOGY cont’d
Mental workload
Requirements and demands made by the tasks on
the employees namely:
 Perception (visual, auditory etc.)
 Information processing, including
cognitive,motivational and emotional aspects
 Memory function
Vigilance
This is the human observer’s state of alertness in
tasks that demand efficient registration and
processing of signals.
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22. PSYCHOLOGY cont’d
Mental fatigue
Symptoms include;
 perception: reduced eye movements, reduced
discrimination of signals, threshold deterioration.
 Information processing: extension of decision
time, action slips, decision uncertainty.
 Memory function:prolongation of information
storages, delay in memory searching processes,
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23. TECHNOLOGICAL ASPECTS
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24. SYSTEMS DESIGN
 Theprimary aspect is the allocation of
functions between man, machine(s) and
procedures.
 Man and machine complement each other.
Machines are powerful, fast and tireless
while men are intelligent, versatile and
adaptive.
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25. WORKSPACE DESIGN
 This should ensure that the physical
surroundings fit the characteristics of the
human body
 Itdepends largely on the application of
anthropometry and biomechanics
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26. ENVIRONMENTAL DESGN
 Allenvironmental parameters should be
appropriate to human requirements.
 Itis concerned with lighting, heating,
ventilation, noise, vibration and all other
environmental parameters.
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27. Examples
Noise
 Solid guards on moving parts replaced with
perforated or wire mesh guards
 Broad belts replaced with narrower belts
separated with spacers
Vibration
 Use of flexible connections on inlets and outlets
of pressure lines
 Mounting of vibrating equipment on dampers e.g
springs, rubber, plastic
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28. WORK SITUATION DESIGN
 This deals with wider issues such as work
organisation as well as interpersonal
aspects of work.
 Itinvolves among others ; hours of work,
rest pauses, shift work, communication,
incentives etc.
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30. Typical Administrative Controls
Training workers in work methods.
Varying or rotating work tasks.
Limiting extended work hours.
Providing mini-breaks.
Take holiday/leave days vs. selling leave
days
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31. CONCLUSION
 Ergonomics demands a two way approach
namely, fitting the job to the worker and
fitting the worker to the job.
 Thetwo way adaptation process is mainly
determined by man’s abilities and
disabilities.
 Ergonomics is interdisciplinary.
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32. Where to Get More Information
 Encyclopaedias of occupational health and
safety - ILO
 Ergonomic Checkpoints - ILO
 Higher Productivity And A Better Place To
Work – ILO
 Safety, Health and Working Conditions –
Training Manual -ILO
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