introduction to ergonomics 2

8/8/2019 Introduction to Ergonomics 2

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What is Ergonomics? The word Ergonomics is derived from the

Greek words Ergon" and "Nomos" which

together mean "The law of work".


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Definition Shackel (1974) "the study of the relation

between man and his occupation,

equipment and environment, andparticularly the application of anatomical,

physiological and psychological knowledge

to problems arising there from".


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Definition Ergonomics Society (1993) "the fit between

people, the activities they wish to carry out,

the tools, machines and systems they useto aid them and theenvironments in which

they are performed".


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Why Ergonomics? Complexity of modern industry, equipment

and tasks

Time and space barriers betweendesigners and users

A whole range of user population (male,

female, elderly) from many differentcultures.


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The Aim ofErgonomics


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History ofErgonomics During the 1700's and early 1800's, great

changes took place in the lives and work ofpeople in several parts of the world. These

changes resulted from the development ofindustrialization.

1911: Scientific management, developed by F. W.Taylor at the turn of the century, was one of the

first attempts at maximizing productivity byimproving the design of tasks rather than thedesign of machines


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1945 to 1960:The Birth ofthe

ProfessionAt theend of the war in 1945, engineering

psychology laboratories wereestablished

by the U.S. Army AirCorps. The name was invented by Murrell in 1949.

It was during the period after the war that

thehuman factors profession was born.


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Profession In Britain, the field ofergonomics was

inaugurated after theSecond World War.

In 1949 the Ergonomics ResearchSociety(now called simply the Ergonomics Society)was formed in Britain, and the first book onhuman factors was published, entitled

Applied Experimental Psychology: HumanFactors in Engineering Design (Chapanis,Garner, and Morgan, 1949).


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Profession The year 1957 was an important yearespecially

forhuman factors in the United States. In that

year thejournal Ergonomics from the Ergonomics

ResearchSociety appeared, the Human Factors

Society was formed.

In 1959 the International Ergonomics Association

was formed to link several human factors andergonomics societies in various countries around

the world.


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1960 to 1980: A Period ofRapid

Growth Until the 1960s, human factors in the

United States wereessentially

concentrated in the military-industrialcomplex. With the race for space and

staffed space flight, human factors quickly

became an important part of the space

program.


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1960 to 1980: A Period ofRapid

GrowthIndication of the growth ofhuman factors

during this period:

Membership of the Human Factors Societywas about 500 (1960)

Membership of the Human Factors Societywas about 3000 (1980)

Membership of the Human Factors andErgonomics Society was about 6000 (2001)


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History ofErgonomics


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Ergonomics as Science

Ergonomics

Toxicology AnatomyManagement

Engineering

Environmental

sciences

Occupational health & safetyPsychologySociology

Computer sciences

Economy

Design

Biomechanics

Physiology


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The Scope ofErgonomics The scope of Ergonomics is extremely

wide and is not limited to any particular

industry or application. Ergonomics comes into everything which

involves people, Work systems, sports

and leisure, health and safety should all

embody ergonomics principles if well

designed.


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The Scope ofErgonomics1. The Focus of Ergonomics

2. The Objectives of Ergonomics

3. The Approach of Ergonomics


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1.The Focus ofErgonomicsPeople and their requirements should be

considered when:

Objects, facilities, systems andenvironments which people use and

operate within are being designed and

developed

Procedures for people to carry out work

and their activities are being developed

Objects, facilities, etc., which involve and

affect people are bein evaluated


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2.The Objectives ofErgonomics To enhance theeffectiveness with which

work and otherhuman activities are carried

out To maintain orenhance certain desirable

human values in the process, health,

safety, satisfaction etc.,


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3.The Approach ofErgonomics

Improving interactions by considering all

components of the work system (Human,Technology, Organization and Information

as well as consideration of the Internal and

External environment in which the system

operates) enables the work system to

function in its optimal condition.


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Anthropometric Principles The word "anthropometry" means

measurement of thehuman body.


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Anthropometric Principles1. Clearance: - Dimensions determine the

minimum space required for a human

being to perform the task in the workplace,such as operating machines and others.

Clearances areestablished by the larger

people from theexpected user population

(e.g., the size of door is determined by thesize of the largest expected user).


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Anthropometric Principles1. Reach:- Dimensions determine the

maximum space allowable for thehuman

being who operates equipment and areestablished by the smaller people in the

expected user population (e.g., control

height is determined by accommodating

shorter user).


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BASIC ERGONOMIC DESIGN

PHILOSOPHIES

Design for the average

Design for extremes

Design for a range


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BODY MEASUREMENT

SStanding

measurements

A1Stature (standing

height)

A2Eyeheight,

standing

A3Elbow height,standing

A4Crotchheight

A5Ankleheight


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BODY MEASUREMENT

SSeated measurement

B1Sitting height, erect

B2Eyeheight, sitting

B3Elbow rest height , sitting (fromseat)

B4Thigh depth (maximum) sitting

B5Shoulder to elbow length

B6Kneeheight, sitting

B7Popliteal height, sitting

B8Buttock to knee length, sitting

B9Buttock to Popliteal length,sitting

B10Forearm hand length


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BODY MEASUREMENT

SBreadth

measurements

C1

Hip breadth, sitting C2Elbow to elbow

breadth

C3Shoulder

(biacromial) breadth C4Shoulder (bideltoid)

breadth

C5Knee to knee

breadth


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BODY MEASUREMENT

SHand measurements

D1Hand breadth

D2Hand breadthacross thumb

D3Hand length

D4Hand thickness

Foot measurement

E1Foot breadth

E2Foot length


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USE OF ANTHROPOMETRIC DATA INDESIGN

To get an appropriate fit between the operator and the design(ofequipment, workplace, etc.), the following procedure forthe use of anthropometric data should be utilized:

1. Define theequipment's for potential user population

2. Choose the proportion of the population to beaccommodated by the design (i.e., 90% and 95% are mostcommon).

3. Determine the body dimensions, important for the design ofthe chosen equipment (forexample, to design hand lever,hand breadth, hand circumference should be measured).

4. Determine the percentile values of the dimensions.

5. Determine the type of clothing and personal protectiveequipment worn by the users (i.e., light summer clothing,heavy winter clothing, gloves, etc.).


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DESIGNT

O FIT

FOR A RANGE


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Generalprinciples for workplace design

1. The worker should be

able to maintain an upright

and forward-facing posture

2.Avoid unbalanced

postures (leaning or

twisting) and the need for

muscle activity to support

the legs and upper arms.

Small and/or precise

movements require support

of the limb(s) involved.


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Generalprinciples

3. Where vision is a

requirement of the task, the

necessary work points must

be adequately visible with

thehead and trunk upright

or with thehead inclined

slightly forward

4.All work activities should

permit the worker to adopt

several different, but

equally healthy and safe

postures without reducing

capability to do the work.


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Generalprinciples

5. Work should be

arranged so that it may

be done, at the worker's

choice, in either a seated

or a standing position.

When seated, the worker

should be able to use the

backrest of the chair at

will, without necessitatinga change of working

movements.


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Generalprinciples 6. The weight of the body

when standing should be

carried equally on both feet,

and foot pedals should be

designed accordingly.


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Generalprinciples 7. Work should not be performed

consistently at or above the level of the

heart, even the occasional performancewhere force is exerted above theheart

level should be avoided. Where light hand

work must be performed aboveheart level,

rests for the upper limbs are a requirement.


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Generalprinciples


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Risk FactorsPhysical factors

Heavy manual labour

Manual material handling

Awkward posture

Static work

Whole body/ hand arm vibration

Slipping and falling


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Risk FactorsPsychosocial/ work organisational factors

Job content

Work/time pressure

Job control

Social support

Job dissatisfaction


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Risk FactorsIndividual factor

Age

Socio-economic status Smoking

Medical history

Gender

Anthropometry

Physical activity


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Risk FactorsEnvironment:

Temperature,

Air quality,

Lighting,

Noise


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Factors to be considered in the

visualenvironment Intensity of illumination

Reflections or luminance

Contrast

Glare


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Lighting forfine work High levels of

illumination are

required for fine work

and between 1,000

and 10,000 luxhas

been suggested for

different levels of

precision.


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Performance in hot environments Exhaustion from heavy physical work occurs much sooner in

hot environments due to the competition for blood supplybetween the skin and the muscles. As it has been mentionedbefore, when the body is hot it increases blood supply to the

vast numbers of capillary beds under the skin, which uses asignificant proportion of the circulating blood and causes areduction in circulation to the muscles and core body organs.

Sweat can affect performance due to discomfort and canaffect the ability to grip objects

Hot environments can have detrimental effects on theperformance of complex cognitive tasks or that involvinghand eye co-ordination.


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Performance in cold environments

Cold temperatures have a considerableeffect on manual

dexterity, the sense of touch and strength. The adverse

effects of cold on manual dexterity can be predicted by

hand skin temperature and 13C

has been suggested asthe lower limit for working withhands exposed.

Loss of tactile sensitivity creates difficulties in the

performance of tasks which require the manipulation of

small objects and reduces the ability to grip.

Additionally, ifexposed for a period of time, overcooling

induces restlessness, which in turn reduces alertness

and concentration, particularly on mental tasks.


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WMSDs Myalgia

Chronic myofascial pain syndrome

Tendinitis

Tenosynovitis Carpal tunnel syndrome

Thoracic outlet syndrome

Hand-arm vibration syndrome

Degenerated, bulging, or ruptured (herniated)disks in the neck or back

Sciatica

Degenerative or osteoarthritis


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References:

Bridger R.S. Introduction to Ergonomics (1995)

Hendrick H.W. & Kleiner B.M. Macroergonomics (2002)

Tayyari, F., and Smith, J.L., 1997, Occupational Ergonomics,

Principles and applications,Chapman & Hall, London, U

K.

PeopleSize, 1994, Visual Anthropometry, version 1.40

Haslegrave, C.M., 1986. Characterising the anthropometricextremes of the population. Ergonomics, 29, 2, 281-30

Pheasant, S., 1990.Anthropometrics - An Introduction.

BritishStandards Institution: Milton Keynes


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Ergonomic

Workplace Analysis


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What are thefour basic steps?Four basic stages in conducting a EWA are:

selecting thejob to be analyzed

breaking thejob down into a sequence oftasks

identifying potential workplace contributingfactors

determining preventive measures toovercome adverseeffects of theseworkplace contributing factors


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Factors to be considered Accident frequency and severity: jobs where accidents occur

frequently or where they occur infrequently but result indisabling injuries.

Potential for severe injuries or illnesses.

Newly established jobs: due to lack ofexperience in thesejobs, workplace contributing factors may not beevident oranticipated.

Modified jobs: new workplace contributing factors may beassociated with changes in job procedures.

Infrequently performed jobs: workers may be at greater riskwhen undertaking non-routinejobs, and EWA provides ameans of reviewing workplace contributing factors.

D i i i


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Determiningpreventivemeasures to overcome

workplace contributing factors

1. Eliminate the contributing factor

2. Revise work procedures 3. Reduce theexposure


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How to improve

ergonomics?I. Engineering improvements

II. Administrative improvements

III. Personal protective equipments


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Engineering

improvementsIt include rearranging, modifying, redesigning,

or replacing tools, equipment, workstations,

packaging parts, or products. Reposition the work- reduces bending &

reaching

Provide comfort


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Administrative

improvementsAdministrative improvements include

changing work practices or the way work is

organized.

Some administrative improvements includes:


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1.Providing variety in jobs

Job rotation rotating the employees

through different jobs.

Job enlargement increasing the variety by

combining two or more jobs or adding tasks

to a particular job.


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2.Adjusting

work schedules and work pace

Try to limit the amount of time any

employee has to spend performing aproblem job.


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3.Providing mini breaks

Work should be broken up with frequent,short recovery periods or mini breaks. These

short breaks (3-5 minutes every hour) can

help prevent the accumulation of fatigue

and injury to muscles and associated

structures.


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4.Modifying workpractices

Pay close attention to how the work is beingperformed. Our bodies are stronger, more

efficient, and less injury prone when work in

midrange postures.


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5.Encouraging exercises


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III.Personalprotectiveequipment

Personal protective

equipment includes

gloves, knees and

elbow pads, footwear,

and other items that

employees wear.


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Making informed choices about

ergonomic improvements

Use in-house human resources

Look through equipment catalogs

Talk to equipment vendors

Contact others in similar organizations

Consult an expert in ergonomics


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Remember!!!An important part of an effective

ergonomics program is training

and education


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TrainingA training program should include the

following individuals:

All affected employees

Engineers and maintenance personal

Supervisors

Managers

Health care providers


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General trainingEmployees who are potentially

exposed to ergonomic hazards

should be given formal instruction

on the hazards associated with

their jobs and with their

equipments


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Job specific training

New employees and

reassigned employees should

receive an initial orientation and

hands on training prior to startingtheir duties.


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Training for

supervisorsSupervisors are responsible persons for

ensuring that employees follow safe workpractices and receive appropriate training toenable them to do so. Supervisors thereforeshould undergo training comparable to that ofthe employees, and such additional training

as will enable them to recognize early signsand symptoms of MSDs, to recognizehazardous work practices, and to correctsuch practices.


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Training for managersManagers should be aware of their

safety and health responsibilities

and should receive sufficienttraining regarding ergonomicissues at each work station and

at the organizational level as awhole so that they can effectivelycarry out their responsibilities.

Tra n ng or eng neers


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Tra n ng or eng neers&

maintenance personal

Plant engineers and maintenance

personnel should be trained in theprevention and correction of

ergonomic hazards through job

and as applied to the specificconditions of the facility.


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