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ErgonomicsErgonomicsA ZengeyaFactories and Works InspectorateNSSA- CHINHOYI

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INTRODUCTION 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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AGENDAAGENDA

SCIENTIFIC ASPECTS

Anatomy Physiology Psychology Work environment

TECHNOLOGICAL ASPECTS

Technological design Workspace design Environmental

design Work situation

design

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Overview 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. Te

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ANATOMYANATOMY

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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BASIC ANTHROPOMETRIC BASIC ANTHROPOMETRIC VARIABLESVARIABLESThese 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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BIOMECHANICSBIOMECHANICS

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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BIOMECHANICS CONT’DBIOMECHANICS 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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PHYSIOLOGYPHYSIOLOGY

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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Factors that Influence PhysiologyFactors that Influence Physiology

Intrinsic FactorsNutrientsMetabolismHeart functionExtrinsic FactorsEnvironmental parametersWorkload

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WORK PHYSIOLOGYWORK 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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WORK PHYSIOLOGY CONT’DWORK 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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WORK PHYSIOLOGY CONT’DWORK 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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ENVIRONMENTAL ENVIRONMENTAL PHYSIOLOGYPHYSIOLOGY

The environmental parameters include among others: Lighting Noise Vibration Climate

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Effects Of Body Temperature On Effects Of Body Temperature On PhysiologyPhysiology 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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Effects Of Noise On PhysiologyEffects 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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Effects of Vibration on PhysiologyEffects of Vibration on Physiology

FatigueVariation of blood vessel pressure &

impaired circulationReduced grip, strength and manual

dexterity as well as reduced sensationGastrointestinal disturbancesDisturbances of the urogenital tractImpaired vision & dizziness

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Effects Of Oxygen DeficiencyEffects Of Oxygen Deficiency

Increased heart rate & depth of breathingDizzinessHeadacheLoss of consciousness/recollectionLocations include;Vats, Silos, Mines, Manholes etc

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Effects of Radiation on PhysiologyEffects of Radiation on Physiology

Increased pulse due to ionizing radiationExcessive temperature rise due to radio

frequency energy (microwave &radar units)

Brain & bone marrow injuryStartle reactions associated with spark

discharges and contact reactions

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PSYCHOLOGYPSYCHOLOGY

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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PSYCHOLOGY cont’dPSYCHOLOGY cont’d

Mental workloadRequirements and demands made by the tasks on the employees namely:

Perception (visual, auditory etc.) Information processing, including

cognitive,motivational and emotional aspects Memory functionVigilance

This is the human observer’s state of alertness in tasks that demand efficient registration and processing of signals.

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PSYCHOLOGY cont’dPSYCHOLOGY cont’d

Mental fatigueSymptoms 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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TECHNOLOGICAL ASPECTSTECHNOLOGICAL ASPECTS

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SYSTEMS DESIGNSYSTEMS DESIGN

The primary 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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WORKSPACE DESIGNWORKSPACE DESIGN

This should ensure that the physical surroundings fit the characteristics of the human body

It depends largely on the application of anthropometry and biomechanics

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ENVIRONMENTAL DESGNENVIRONMENTAL DESGN

All environmental parameters should be appropriate to human requirements.

It is concerned with lighting, heating, ventilation, noise, vibration and all other environmental parameters.

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ExamplesExamples

Noise Solid guards on moving parts replaced with

perforated or wire mesh guards Broad belts replaced with narrower belts

separated with spacersVibration 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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WORK SITUATION DESIGNWORK SITUATION DESIGN

This deals with wider issues such as work organisation as well as interpersonal aspects of work.

It involves among others ; hours of work, rest pauses, shift work, communication, incentives etc.

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Typical Administrative ControlsTypical Administrative ControlsTraining 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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CONCLUSIONCONCLUSION

Ergonomics demands a two way approach namely, fitting the job to the worker and fitting the worker to the job.

The two way adaptation process is mainly determined by man’s abilities and disabilities.

Ergonomics is interdisciplinary.

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Where to Get More InformationWhere to Get More Information

Encyclopaedias of occupational health and safety - ILO

Ergonomic Checkpoints - ILOHigher Productivity And A Better Place To

Work – ILOSafety, Health and Working Conditions –

Training Manual -ILO