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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    1945 to 1960:The Birth ofthe

    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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    1945 to 1960:The Birth ofthe

    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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