element ib9 (part 2)

7/17/2019 Element IB9 (Part 2)

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© RRC Training Unit IB – Element IB9 | 9-5

Element IB9: Musculoskeletal Risks and Controls

• Many risk factors influence the risk of MSDs associated with a particular activity. These include repetition, force,posture, twisting, rest, equipment design, equipment adjustability, lighting, other environmental parameters andindividual capabilities.

• MSD risk assessments often follow a format established by relevant legislation. For example, a manual handlingrisk assessment might consider the load, task, environment and individual capabilities.

• Assessment tools are available to assist with the risk assessment of both manual handling and repetitiveactivities. The UK HSE have published two such tools; the Manual Handling Assessment Charts (MAC) andAssessment of Repetitive Tasks (ART) tools. Other tools are available, such as the Manual Material Handling(MMH) checklist, Rapid Upper Limb Assessment (RULA) tool and the Quick Exposure Check.

• The control measures introduced following such risk assessments will vary depending on the nature of the

activity in question. Manual handling control measures are very different from those employed for DSE use.Generally, hazard elimination by automation or mechanisation are the preferred solutions. Where this is notpossible, the provision of equipment and aids, task redesign and alterations to the work environment might beused. Ultimately control may rely on good practices regarding posture and technique. This will require training.

Assessing and Controlling Musculoskeletal Risks

Risk FactorsThere are some risk factors that contribute to ergonomicrisk in general. These include:

• Repetition – the need for repetitive movements

when carrying out the task (e.g. typing for severalhours).

• Force – the physical force required to perform thetask and the strain this puts on the body (e.g. closingstiff catches on a machine).

• Manual handling – if there is a requirement to carryout a degree of manual handling (even of light loads)this can increase the risk of ergonomic injury. Forexample, an operator on a production line who islifting small boxes for packaging is more at risk of aninjury.

• Posture – any requirement to adopt an awkwardposture (e.g. stooping over into a bin to pick outcontents).

• Twisting – any twisting action required by the task(e.g. twisting the wrist when using a screwdriver).

• Rest – the potential for the worker to rest andrecover from any fatigue (e.g. a worker on aproduction line cannot stop the line; they have tokeep working even when fatigued).

• Equipment design – the shape of the equipmentand how this affects ease of use (e.g. a large, shaped

handle on a scraper makes it easier to hold and use).

• Equipment adjustability – the scope there isfor the user to adjust the equipment to suit their

personal preferences (e.g. the height of the seat for acomputer user).

• Lighting – the availability of natural and artificial lightand the effect on the worker’s ability to see the work

clearly.• Other environment parameters – in particular

temperature, humidity and ventilation will directlyaffect the worker’s ability to perform the task andtheir comfort.

• Individual capabilities – of the person doingthe work. In particular young persons and newand expectant mothers may be given additionalprotection under national legislation. Othervulnerable groups might include disabled peopleand those with a known existing injury or i ll-healthcondition (such as recovering from surgery).

Risk Assessment MethodsThe ergonomic risk assessment method applied to awork activity will depend to a large degree on the natureof the work activity and any specific legal requirementsthat are in place. In particular, manual handling and theuse of DSE may each have their own risk assessmentmethods under their respective legislation and guidance(as in the UK, for example).

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Unit IB – Element IB9 | 9-6 © RRC Training


Assessing Manual Handling Risk

When a manual handling activity cannot be completelyeliminated then it must be assessed in order to reducethe risk of injury. This risk assessment will be slightlydifferent from the general risk assessment you arealready familiar with because it focuses exclusively on thehazard of manual handling and ignores all other hazards.

Manual handling risk assessment focuses on four mainfactors:

• The task.

• The load.

• The environment.

• Individual capabilities.

The Task

The focus here is on the movements required of theworker as they handle the load. The task can be assessedby asking questions such as:

• At what height is the load being picked up, carried orput down?

• Is the task very repetitive?

• Is a long carrying distance involved?

• Does the task involve stooping (worker has to keeptheir legs straight and bend their back) to move theload? Does the task involve twisting (turning the

shoulders while the feet stay still)?

• Can rest breaks be taken as the worker requiresthem?

• Does the task involve lifting the load through avertical distance?

• Does the task involve reaching above shoulderheight? Does the task involve the worker holding theload away from their trunk (torso)?

Holding a load away from your torso when lifting increases the riskof injury

The Load

Here the focus is the load that is being handled.Though the load is usually an inanimate object, in someworkplaces it may be an animal or a person, e.g. in ahospital, patients have to be moved from bed to gurney

(a wheeled stretcher/trolley), from wheelchair to bath,etc.

The load can be assessed by asking questions such as:

• How heavy is the load?

• How large and bulky is the load?

• How stable is the load?

• Where is the centre of gravity (C of G) of the load?

• Is the load difficult to grip?

• Is the load hot, sharp or otherwise hazardous?

The Environment

The focus here is the environment in which the handlingtakes place.

The environment can be assessed by asking questionssuch as:

• Are there restrictions on the space available?

• Is the floor surface slippery or uneven?

• Are there changes in floor level (steps, stairs, etc.)?

• What are the light levels like?

• What is the temperature and humidity?

Individual Capabilities

The focus here is on the worker carrying out thehandling activity.

Individual capabilities can be assessed by askingquestions such as:

• Does the activity require unusual ability? Somehandling activities require unusual strength, stamina,size or technique.

• Does the activity present significant risk to vulnerableindividuals such as pregnant women or people withpre-existing back injuries?

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DSE Workstation Assessment

A DSE risk assessment of the user’s workstation maybe required by national legislation to ensure that theequipment and environment meets minimum standardsand that the workstation can be adjusted to suit theuser. An example of this is the UK’s Health and Safety(Display Screen Equipment) Regulations 1992 (asamended).

During the DSE assessment it will be necessary to checkthe:

• Screen.

• Keyboard.

• Chair (including foot rest – if required).

• Desk.

•

Other associated equipment such as telephone.• Environment, such as lighting, space, noise and

temperature.

Risk assessment of DSE workstations may be required by nationallegislation

We will consider the controls which can be implementedas a result of such a risk assessment later in the element.

The HSE in the UK has published a wealth ofinformation at:

http://www.hse.gov.uk/msd/dse/index.htm

An excellent checklist for carrying out a DSEworkstation assessment is available at:

http://www.hse.gov.uk/campaigns/euroweek2007/pdfs/vduchecklist.pdf

Use of Assessment ToolsA variety of assessment tools have been developedto assist in the assessment of manual handling andrepetitive activities. The detail of these tools varies, butthe general approach is similar: they examine individualrisk factors associated with the task and allocate anumerical score accordingly. The numerical score for riskfactors is then summed and the total score is used to:

• Give a general indication of MSD risk level andacceptability/tolerability.

• Prioritise tasks according to MSD risk.

• Highlight individual risk factors that make the mostsignificant contributions to total score so that thoserisk factors can be addressed.

It should be noted that these assessment tools do not

themselves constitute a full risk assessment that wouldachieve legal compliance, but are simply aids in theassessment process.

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Manual Handling Assessment Charts (MAC)Tool

The MAC tool was developed by the UK HSE primarilyfor inspectors to use during inspection visits as a quicktool to identify and quantify the level of risk associatedwith manual handling operations. The tool has sincebeen published by the HSE as a tool for assisting in themanagement of manual handling risk.

The MAC tool uses a numerical score and a traffic lightapproach to indicate the level of risk. Three types ofmanual handling operation can be assessed:

• Single lifting operations.

• Single carrying operations.

• Team handling operations.

Each operation is divided into the different manualhandling risk factors and presented as a flow chart.During use an operation has to be observed and the flowchart used to guide the user through each factor of themanual handling operation to grade the degree of risk.

The risk factors assessed include:

A Load weight/frequency

B Hand distance from the lower back

C Vertical lift region

D Trunk twisting and sideways bending

E Postural constraints

F Grip on the load

G Floor surface

H Other environmental factors

An example of one risk factor and the possible scoresallocated is shown in the following figure:

Example Risk AssessmentSource: INDG383 Manual handling assessment charts, HSE, 2003 (http://www.hse.gov.uk/

pubns/indg383.pdf)

Colour-coding for each of the risk factors allows foreasy identification of the significant contributing riskfactors. The MAC flow diagram for a lifting operation isillustrated in the following diagram.

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MAC Flow Diagram

Source: INDG383 Manual handling assessment charts, HSE, 2003 (http://www.hse.gov.uk/pubns/indg383.pdf)

The UK HSE publication INDG383 Manualhandling assessment charts is available at:

http://www.hse.gov.uk/pubns/indg383.pdf

Information on the MAC tool, including adownloadable version of the tool, is available at:

http://www.hse.gov.uk/msd/mac/

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Assessment of Repetitive Tasks (ART) Tool

The Assessment of Repetitive Tasks (ART) tool wasdeveloped by the UK HSE to assist in the assessment oftasks that require repetitive moving of the upper limbs(arms and hands). It examines some of the commonrisk factors in repetitive work that contribute to thedevelopment of Upper Limb Disorders (ULDs).

In general approach the ART tool is similar to the MACtool. A specific activity is observed for a period of time,a description of the activity is made, then a series ofspecific risk factors are examined and scored, using atraffic light colour coding system to indicate significantrisk factors.

Risk factors include:

A Frequency and repetition

A1 Arm movementsA2 Repetition

B Force

C Awkward postures

C1 Head/neck posture

C2 Back posture

C3 Arm posture

C4 Wrist posture

C5 Hand/finger grip

D Additional factors

D1 BreaksD2 Work pace

D3 Other factors

D4 Duration

D5 Psycho-social factors

An example of one risk factor and the possible scoresallocated is given in the following figure:

Source: INDG438 Assessment of repetitive tasks of the upper limbs (the ART tool), HSE, 2010 (http://www.hse.gov.uk/pubns/indg438.pdf)

The overall risk score is calculated by summing thescore for factors A1-D3. The sum is then multiplied bya duration multiplier (D4) which is derived from thelength of time that a worker performs the activity duringa day (this multiplier ranges from 0.5x to 1.5x). D5 is not

assigned a score, but identifies additional factors to beconsidered.

Overall exposure scores can be used to prioritiserepetitive tasks on the basis of ULD risk and can also beused to give an indication of acceptability/tolerability.

ExposureScore

Risk Action

0-11 Low Consider individualcircumstances

12-21 Medium Further investigation required

22 or more High Further investigation requiredurgently

Information on the ART tool, including adownloadable version of the tool is availablefrom the following websites:

http://www.hse.gov.uk/msd/uld/art/index.htm

http://www.hse.gov.uk/pubns/indg438.pdf

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Other Assessment Tools

In addition to these two HSE published tools, otherassessment tools are available from alternative sources:

• Manual Material Handling (MMH) checklist

is published online by the National Institute ofOccupational Safety and Health (NIOSH), areputable American source. It is similar to, but lesswell developed and supported than, the MAC tool.

To download a copy of the MMH checklist, visit:

http://www.cdc.gov/niosh/docs/2007-131/pdfs/2007-131.pdf

Additional material is also available at :

http://www.dir.ca.gov/dosh/etools/08-004/tool2.pdf

• The Rapid Upper Limb Assessment (RULA) tool has been developed by ergonomists at the Universityof Nottingham in the UK. A RULA gives a quickand systematic assessment of the postural risks toworkers. One benefit of RULA over ART is that moredetailed examination of left and right arm, wristand hand position and movement is inherent in the

tool, along with consideration of head, back and legposition and movement.

Similar to the ART tool, the result of the testis a RULA score that can be used to prioritisecomparative risk and indicate the urgency of theneed for change, as shown in the following table.

Actionlevel

RULAscore

Action

1 1-2 Working in the best posture withno risk of injury from their work

posture.2 3-4 Working in a posture that could

present some risk of injury fromtheir work posture, and this scoremost likely is the result of one partof the body being in a deviated andawkward position, so this should beinvestigated and corrected.

3 5-6 Working in a poor posture witha risk of injury from their workposture, and the reasons for thisneed to be investigated and changed

in the near future to prevent aninjury.

4 7-8 Working in the worst posture withan immediate risk of injury fromtheir work posture, and the reasonsfor this need to be investigated andchanged immediately to prevent aninjury.

•

An online version of the RULA tool is available at:

http://www.rula.co.uk

Quick Exposure Check is a posture and ULDassessment tool similar to the ART tool. It is availablefrom several Web-based sources.

An explained version of the Quick ExposureCheck is available in a UK HSE research paper at:

www.hse.gov.uk/research/rrpdf/rr211.pdf

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Practical Control MeasuresIn general terms the control of ergonomic risk can beachieved by introducing changes to:

• the task and the way that it is done,

• the tools, equipment and machinery, and

• the workplace environment,

so as to suit the individuals carrying out the work.

In some cases, it may be appropriate to put restrictionson the individuals doing the work (i.e. restricting thosepeople who have a known WRULD to light duties toavoid further injury).

The first step in achieving controls is to undertake a riskassessment. This risk assessment may follow a standardformat as indicated by specific national legislation, or

may be a general risk assessment utilising the ART tool,RULA or some other aid.

The controls identified by the risk assessment willinevitably vary depending on the nature of the taskbeing assessed. Several examples of control options arediscussed below, classified according to work activity.

Display Screen Equipment Control Measures

The following control measures are appropriate for DSEuse:

• Carry out a workstation assessment of the user’s

workstation to ensure that the equipment andenvironment meet minimum standards and that theworkstation can be adjusted to suit the user.

• Provide basic DSE workstation equipment thatmeets minimum standards in terms of goodergonomic design.

• Plan the user’s work routine so that they can takeshort, frequent breaks from screen and keyboard use.

• Provide DSE users with a free eye test and, ifrequired, spectacles for screen use.

• Provide information and training to users on the

potential health risks of DSE use and the preventivemeasures, in particular ergonomic use of theworkstation.

Some of the minimum standards for workstationequipment and the good practices relating to postureand workstation use are illustrated in the followingfigure.

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Good Ergonomics at a DSE Workstation(Based on original source L26 Work with display screen equipment (2nd ed.), HSE, 2003 (http://www.hse.gov.uk/pubns/priced/l26.pdf))

The numbered issues are as follows:

1. Adjustable height and angle to seat back.

2. Good lumbar support.

3. Adjustable height seat to bring the hands to acomfortable position on the keyboard. Seat also has astable 5-star base.

4. Correct seat height adjustment and keeping the feetsupported prevents excess pressure on underside ofthighs and backs of knees.

5. Foot support if user cannot get their feet on thefloor.

6. Space for postural change, no obstacles under desk;this allows the user to fidget and change position asthey work.

7. Forearms approximately horizontal when hands areon keyboard.

8. Minimal extension, flexion or deviation of wrists;wrists should be straight and flat when on thekeyboard indicating proper seat height adjustment.

9. Screen height and tilt should be adjustable so as to

allow comfortable head position.10. Space in front of keyboard to support hands/wrists

during pauses in keying; a wrist-rest can providefurther support if required.

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Additional points:

• The desk should be laid out to minimise the need fortwisting or over-reaching (e.g. when reaching for atelephone).

• A document holder may be required.

• If frequent telephone use is necessary when using thekeyboard then a headset may be necessary.

• Workplace lighting should be provided so as to avoidreflections on the screen and glare.

• Unfortunately some of these good ergonomicprinciples cannot be applied to use of a laptopcomputer. If laptops are going to be used in theworkplace then:

– Allow short- but not long-duration use.

– When laptops are going to be used for longdurations, apply the same management approachof workstation assessment, frequent breaks,eyesight tests for users, information and training.

– Provide a docking station and/or separate screen,keyboard and mouse as required to allow theuser to convert the laptop to a more adjustableconfiguration.

Factory Assembly Line Control Measures

The control measures appropriate for the factoryassembly line are very similar to those applied in the caseof DSE use:

• Carry out an ergonomic assessment of theworkstation to ensure that it is appropriate and canbe adjusted to suit the worker’s needs.

• Plan the worker’s work routine so that they can takerecovery breaks.

• Provide information and training to workers onthe potential MSD health risks and the preventivemeasures, in particular ergonomic use of theworkstation.

Specific controls might include:

• Automate the process to eliminate the MSD riskentirely.

• Change the layout of the workstation to allowcomfortable posture and to minimise over-reaching,stooping, twisting, etc.

• Provide seating if it is not already available.

• Provide comfortable shoes and floor mats to relievefoot pressure if sitting is not possible.

• Allow short, frequent breaks from the productionline or introduce job rotation to prevent long

duration on one task.• Ensure lighting is appropriate to the task (brightness

or lux levels should be relatively high for fine detailwork).

• Introduce ergonomically-designed hand tools.

Manual Handling Control Measures

Control of manual handling risk can be achieved by usinga simple hierarchy of controls:

• Eliminate the manual handling.

• Assess the manual handling that cannot beeliminated.

• Use handling aids.

• Modify the task, load or environment.

• Ensure individual capabilities are matched to theactivity.

Eliminate the manual handling – by automation ormechanisation of the handling activity. Conveyor belt

systems, forklift trucks, electric pallet trucks, cranes,hoists and other types of mechanical moving or liftingequipment provide a way of moving loads without theneed for workers to use bodily force.

Electric Hoist Moving Load

Assess manual handling that cannot be eliminated –by looking at the four factors of: task, load, environment,and individual capabilities.

Use handling aids – consider the use of a piece ofequipment that does not completely eliminate themanual handling but does make it much easier. Forexample, a sack truck does not eliminate the need topush the load, but it does eliminate the need to carry it.

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There are many handling aids available such as: trolleys,barrel lifts, gin wheels, trucks, hoists and l ifts that requiresome manual effort to lift or support the load, but givethe worker mechanical advantage.

Modify the task, load or environment – when theappropriate questions we listed earlier are answered,there are usually some simple solutions that presentthemselves.

Modifications may be possible to reduce the significantrisk factors, such as the:

• Task:

– Control repetitive handling by introducingfrequent rest breaks or job rotation to minimisethe length of time that an individual worker hasto perform the task.

– Eliminate stooping and twisting by changing thelayout of the workstation.

– Use a table or lift to bring the load to waist heightto eliminate picking up from floor level.

• Load:

– Break down a heavy load into smaller parts.

– Use several workers to handle a large, bulky loadrather than just one.

– Stabilise an unstable load by securing it or puttingit into a container.

– Mark up a load with an off-centre C of G so thatworkers can see where the C of G is.

– Attach handles to a load that is difficult to grasp.• Environment:

– Rearrange the workspace to allow more space forthe handling activity.

– Level an uneven floor.

– Supply additional lighting in a poorly lit location.

Ensure individual capabilities are matched to theactivity – if the activity requires unusual ability thenworkers must have that ability. For example, if unusualstrength and size are required then the worker must havethose characteristics; if a particular technique is requiredthen the worker must be trained so that they developthat technique.

If the activity presents significant risk to vulnerableindividuals such as pregnant women or people with pre-existing back injuries then those people will have to beprohibited from carrying out the activity.

Safe Lifting Technique

Employees should be trained in basic safe liftingtechnique. This technique minimises the risk ofmusculoskeletal disorders.

•Before Lifting

– Check the weight, C of G and stability of the load.

– Plan the route of the carry.

– Establish a firm grip.

• The Lift

– Bend the knees and use the leg muscles to lift.

– Keep the back upright.

– Keep the load close to the body.

– Avoid twisting, over-reaching, jerking.

• Setting Down

– Use the same principles as when lifting.

– Maintain good balance.

– Set the load down and then adjust its positionusing body weight.

General guidance is available from:

http://www.hse.gov.uk/msd/index.htm

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Revision Questions

3. What risk reduction measures can beintroduced to avoid the development ofWRULDs?

4. Summarise the requirements relating to thefollowing elements of DSE workstations:

(a) Work surface/desk.

(b) Keyboard.

(c) Chair.

(d) Space.

5. What alterations could you suggest to theorganisation of a display screen operator’stasks in order to reduce the physical stress thathe/she may be exposed to?

6. What are the characteristics of the load whichpresent a hazard during manual handlingoperations?

7. Identify the main hazards presented by theworking environment in respect of manualhandling operations.

8. What is the primary means of minimising thehazards of manual handling?

9. How can manual handling tasks be redesigned

to make them less hazardous?

(Suggested Answers are at the end of the book.)

element ib9 (part 2)

Documents

ergonomic risk

risk of msds

assessment tools

degree of manual handling

risk of ergonomic injury

equipment adjustability

equipment design

msd risk assessments