2 vibrations
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2 VibrationsTRANSCRIPT
Guide for Risk Assessmentin Small and Medium Enterprises
8 Hazards arising from whole-bodyand hand-arm vibrations
Identification and Evaluation of Hazards; Taking Measures
Section for ElectricitySection for Iron and MetalSection for Machine and System Safety
Hazards arising from whole-bodyand hand-arm vibrations8
Guide forRisk Assessment inSmall and Medium Enterprises
Identification and Evaluationof Hazards;Taking Measures
Section for ElectricitySection for Iron and MetalSection for Machine and System Safety
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Imprint
Authors: Dr.-Ing. Gerhard NeugebauerISSA Section Metal, Germany
Dipl.-Ing. Laurencia JancurovaNational Labour Inspectorate, Košice, Slovakia
MD Janos MartinNational Institute for Occupational Hygiene and Medicine (OMFI),Budapest, Hungary
Dipl.-Ing. Zdenek JandakSZU, Czech Republic
Ing. Thomas ManekISSA Section Metal, AUVAAustria
Production: Verlag Technik& Information e.K.,Wohlfahrtstrasse 153, 44799 Bochum, GermanyTel. +49(0)234-94349-0, Fax +49(0)234-94349-21
Printed in Germany � April 2010
ISBN 978-3-941441-52-1
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This brochure is to meet the demand forrisk assessment and exposure reductionin connection with vibration exposure atwork and to serve the purpose of imple-menting, at national level, the Directive“Vibrations” (2002/44/EC) in small andmedium-sized enterprises.
The brochure is structured as follows:
1. Fundamentals2. Risk Assessment3. Annex 1 and 2
Note:This brochure serves the purpose oftransposing into national law theFramework Directive on the introduc-tion of measures to encourage im-provements in the safety and healthof workers at work (89/391/EEC) andthe Individual Directive “Vibrations”(2002/44/EC) enacted under it. All andany relevant provisions transposed
into national law shall be compliedwith (see page 23).This brochure does not deal with thedocumentation of risk assessment, asthe relevant provisions vary considerab-ly from member state to member state.
In addition to the present brochure,guidelines on the following subjects arebeing planned or already available:
� Noise
� Chemical hazards
� Hazards arising from electricity
� Hazards arising from explosions
� Hazards arising from machineryand other work equipment
� Slipping and falling from a height
� Physical strain(e.g. heavy and one-sided work)
� Mental workload
Introduction
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1. Fundamentals
Exposure to vibrations may affect humanbeings in a variety of ways ranging frommere annoyance to impairment of per-formance, health hazards and even dam-age to health.
Vibrations take the form of● Hand-arm vibrationsduring work with vibrating hand-heldmachinery such as grinders, clippinghammers, rammers, plate vibrators,rock drills, breakers, hammer drills,chain saws etc.
● Whole-body vibrationson mobile machinery and equipmentsuch as (construction site) lorries, for-
est machines, graders, wheel orcrawler-type loaders, tractors, fork-lifttrucks operating on uneven ground,military vehicles.They may also occur at stationaryworkplaces next to heavy machinery,such as control platforms on compres-sors or punch presses.
The harmful effects of vibrating toolsor machines have long since beenknown but are still frequently under-estimated.
1.1 Protection of safety and health
Vibrations may affect the whole bodyor parts thereof.
Whole-body vibrations (WBV) aremechanical vibrations transmitted tothe body via the buttocks or back in thecase of sedentary work, via the feet inthe case of work performed while stand-ing or the head and back when working insupine position.
They affect the whole body.
Whole-body vibrations may also occurduring leisure time, for instance when go-ing by car or motor bike.
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Hand-arm vibrations (HAV) are me-chanical vibrations transmitted via thehands and affect only or mainly the hand-arm system.Hand-arm vibrations are for instancecaused by hand-held electrical or pneu-matic tools including hedge trimmers andthe like.
Vibrations and healthAs in the case of sound, a number ofparameters and effects on human healthare known with regard to mechanicalvibrations.
Health hazards depend on the site ofimpact, the intensity of exposure anddaily recurrence of exposure overyears.
Avoid such hazards!The strain to which individuals areexposed depend on● intensity of vibrations,● frequency,● duration of exposure,● working techniques and● type of activity.
The way vibrations are experiencedby individuals may also be affectedby● their state of health,● the kind of activity performed and● the individual’s attitudeand expectations.
Health hazards occur whenever strong-ly felt vibrations are transmitted● to the hand-arm system and● in the case of work performedwhile standing or sitting, to the wholebody.
Hand-arm vibrations
Hand-arm vibrations impair subjectiveperception, fine motor skills and perform-ance, and may, after years of exposure,cause● circulation disorders,● nerve function disorders,● muscular tissue changes and● bone and joint damage.
Exposure to high-frequency vibrationsover years may lead to circulation dis-orders in the fingers: workers may sufferperiodic attacks in which the fingers be-
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come white and numb (white finger orhand-arm vibration syndrome). The con-dition is also known as vibration-inducedvasospastic syndrome.
Intense low-frequency hand-arm vibra-tions may also cause degenerativechanges of the hand bones, finger jointsand wrists as well as the elbow andshoulder regions. The condition is painfuland may impair mobility.
Joint damage may involve:
● the wrists
● the elbow joints
● the AC (acromioclavicular) joints.
In addition, lunate necrosis and/or fatiguefractures may occur in the region of thecarpal bones.
Working in a cold environment increasesthe risk for these conditions.
Whole-body vibrations may
● impair the senses and may leadto balance disorders, kinetosesor visual disturbances,
● impair fine motor skills or reduceperformance,
● cause stomach troubles or
● affect the spine.
Note:
Please note that preventive measureshave to be taken in particular with regardto certain groups of persons, e. g. youngor older workers, pregnant women.
1.2 Legal basis
Legislation on preventive measures withregard to vibration exposure is basedon the EC Directive “Vibrations“(2002/44/EC), which defines measuresas well as action values and exposurelimit values.
These stipulations in combination withstandards ISO 2631 and ISO 5349,which contain state-of-the-art findingson the measurement and assessment ofvibrations at the workplace, requireemployers to determine and assessthe risks, to duly inform workers and todraw up a programme for the reductionof vibrations.
The objective of the regulations is todefine preventive measures for diseasesof the musculoskeletal system (e. g.spine, bones, joints) as well as circula-tion disturbances in the fingers andhands.
Action and exposure limitvalues “Vibrations“The daily exposure limit shall be calcu-lated on the basis of a standardisedeight-hour reference period A(8). Meas-urement of accelerations is frequency-
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weighted and the values determinedconverted by means of procedures out-lined in national standards.
The European Directive (2002/44/EC)defines exposure limit and action valuesas follows:
Hand-arm vibrations● Exposure limit value A(8) = 5 m/s2
● Action value A(8) = 2.5 m/s2
Whole-body vibrations● Exposure limit value for all directionsA(8) = 1.15 m/s2
● Action value for all directionsA(8) = 0.5 m/s2
Note:Implementation shall respect country-specific differences (see page 23).
In some cases an individual assessmentand evaluation will be necessary.
Depending on the action values/ex-posure limit values the following stepsshall be taken
● Appropriate determinationand assessment of risks
● Implementation of technologicaland organisational measures
● Elaboration and implementationof a programme to reduce vibrations
● Information and instructionof the workers
● Health monitoring
● Provision of additional equipment(e.g. handles)
● Personal protective equipment(e.g. special anti-vibration gloves)
Attention:In recent years the weighting filters forwhole-body vibrations have been adapt-ed to the latest scientific findings so thatin some cases new measurements ormeasurement series may be useful.
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By an assessment of risks possible ex-posures can be recognised and reducedat an early stage. The assessmentprocess can be
● activity-related,
● machine-related,
● work-place-related and/or
● performed on an individual basis.
Exposures are to be evaluated on thebasis of the degree of severity and theprobability of harmful effects.
The most important steps to be takenare:
Step 1: Determination of hazards(i.e. hazards due to vibrations)
Step 2: Estimation and evaluation ofrisks
Step 3: Reduction of risks andtaking measures
Step 1:Determination of hazards
The employer is obliged to assess work-place conditions on the basis of EC-Directive 2002/44/EC as transposedinto national law. In the absence ofempirical data measurements will haveto be performed, which normally requirespecial expert knowledge and expensivemeasuring devices.
Annex 1 gives detailed information onhow to proceed when measurementsare performed at workplaces.
In practice complicated measurementsof typical vibration exposures can beavoided by resorting to catalogues,data bases (Internet) or to data providedby manufacturers (e. g. instructions foruse). In many cases accident insurersor supervisory authorities will supplyinformation on activities or workpla-ces considered harmful because ofvibration exposure (e. g. occupationaldiseases caused by long-term vibrationexposure).
Manufacturers’ data
The Machinery Directive 2006/42/ECprovides the legal framework for machin-ery safety to be complied with by ma-chinery manufacturers or providers.
Manufacturers are obliged to provide da-ta on vibrations generated by machineryin the form of measured results under“test conditions”.
When evaluating workplaces the dataprovided by manufacturers will have tobe critically checked and, if necessary,recalculated to meet actual working con-ditions.
Conversion factors for typical machi-nery (conversion of test-stand con-ditions to immission values) are beingprepared.
These data are helpful for the procure-ment of low-vibration equipment, in im-plementing and adhering to state-of-the-art vibration reduction methods and indrawing up a programme to minimisevibrations.
2. Risk Assessment
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Checklists for Risk Assessment
Checklists are a useful tool for riskassessment.
Check list:Hand-arm-vibrations (HAV)1. Has it been checked whether hand-held or hand-guided machinery andtools that might have harmful effectson the joints can be replaced byother tools?
2. Has it been checked whether high-speed machinery and tools (frequen-cy range 20 to 1000 Hz) that mighthave harmful effects on the handscan be replaced by other tools?
3. Have measures been taken to pre-vent the daily vibration exposure(total value related to an eight-hourperiod) from exceeding the valueA(8) = 2.5 m/s2?
4. Has information on action and ex-posure limit values been passed on?
5. Are low-vibration machinery andequipment (e.g. sanding disks) beingused?
6. Have the grips been fitted with damp-ing or cushioning elements?
7. Have methods to reduce or elimi-nate excessive vibrations beenchecked?
8. When procuring new equipment, issufficient care taken to choose onlylow-vibration tools (on the basis ofthe data the manufacturers areobliged to supply)?
9. Are high grip and pressing forcesavoided by the use of suitable equip-ment and tools?
10. Have special anti-vibration glovesbeen tested (in particular in the case
of outdoor work or work in a coldenvironment) and are they actuallyused?
11. Are preventive medical checkupsoffered to workers exposed to ex-treme vibrations?
Check list:Whole-body vibrations (WBV)
1. Have measures been taken toavoid the maximum daily vibra-tion exposure (effective value ofthe frequency-weighted accelera-tion standardised to an 8-hourperiod) from exceeding the valueA(8) = 0.5 m/s2?
2. Has information on action andexposure limit values been passedon?
3. Can driving in an unfavourable ortwisted body position be avoided?
4. Has care been taken to ensure thatroad surfaces are smooth and arepotholes or other road surface dam-age prevented?
5. Has it been checked whether workcan be organised in a way that per-mits a reduction of the durationof driving periods (duration of ex-posure)?
6. When procuring new vehicles, is suf-ficient care taken to choose onlylow-vibration vehicles (on the basisof the data the manufacturers areobliged to supply)?
7. Have low-vibration seats been in-stalled, properly adjusted and arethey regularly serviced?
8. Are preventive medical checkupsbeing offered to workers exposedto extreme high vibrations?
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Step 2:Estimation and evaluationof risks
Determination of exposureand the A(8) value
Exposures at work can be assessed onthe basis of data provided by manu-facturers or obtained from the literatureor on the basis of measurements.
Parameters are frequency-weightedaccelerations in three directions, obser-vation of maximum values and/orvibration total values (vectors).Annex 2 describes the parametersfor exposure assessment.
Further parameters,e.g. grip forces
Unfavourable working conditions (work-ing postures) and worn-down tools mayresult in increased exposures.
High grip and pressing forces increaseexposures.
Working in a cold environment increasesrisks.
Use of data from data bases
The Internet already provides a num-ber of data bases which may be usedto determine workplace exposure tovibrations (e. g. the data base „KARLA).These data bases mostly supply immis-sion values which considerably differfrom those supplied by manufacturersin the form of emission values. EU Prac-tical Guides and vibration parametercalculators are also useful (available onthe Internet).
Note:Never confuse emission data withimmission values.
Step 3:Reduction of risks and takingmeasures
1. Fundamentals
As stipulated by the Regulation theemployer is under the obligation to resortto technological and/or organisationalcorrective measures whenever actionand exposure limit values are exceeded.These measures include, e. g. alternativeworking processes, selection of suitabletools and materials or the reduction ofthe duration and intensity of exposure.Priority should be given to reductionmeasures at the source.
Protective measures should always betaken in the order S-T-O-P:
S: Substitution
T: Technological solutions, e. g. low-vibration machinery, tools and ve-hicles
O: Organisational measures, e.g. limit-ing intense vibration exposure to cer-tain periods
P: Personal protective measures, e.g.use of anti-vibration gloves to reducehand-arm vibrations, which are, how-ever, only available and effective inrespect of higher-frequency vibrationcomponents.
2. Measures againsthand-arm vibrations (HAV)
Depending on the intensity and durationof hand-arm vibration exposure thefollowing measures shall be taken:
Daily exposure value A(8) = 2.5 m/s2
● Inform your workers and instructthem as to the risks of vibration ex-posure
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Daily exposure value A(8) > 2.5 m/s2
● Draw up and implement a programmeto reduce vibrations
● Offer your workers preventive medicalcheck-ups
Daily exposure value A(8) > 5 m/s2
● Measures have to be taken immedi-ately to avoid such excessive ex-posures!
● Take care to ensure regular preven-tive medical check-ups!
3. Measures againstwhole-body vibrations (WBV)
In the case of whole-body vibrations thefollowing measures shall be taken:Daily exposure value A(8) = 0.5 m/s2
● Inform your workers and instruct themas to the risks of vibration exposure
Daily exposure value A(8) > 0.5 m/s2
● Draw up and implement a programmeto reduce vibrations
● Offer your workers preventive medicalcheck-ups
Daily exposure value A(8) > 0.8 m/s2
and 1.15 m/s2*), respectively
● Measures have to be taken immedi-ately to avoid such excessive ex-posures!
● Take care to ensure regular preven-tive medical check-ups!
4. Measures to be taken at source
In order to reduce exposure at the work-place, the generation, transmission andimpact of vibrations have to be avoided.The most important protective measures
are those which effect a reduction ofvibrations at source.
These primary measures reduce all otherharmful effects regardless of the place andtime of their occurrence and other actionmechanisms.
Reduction ofhand-arm vibrations (HAV)
A few practical examples will illustratehow HAV can be reduced on tools andmachinery:
● Reduction of the coupling intensity(e.g. reduction of grip force)
● Use of compression riveters or recoil-reduced rivet hammers for the pro-duction of riveted joints
● Use of torque screwdrivers instead ofimpact wrenches when assemblingbolted connections
● Use of drill hammers rather thanwidely used impact drills in plumbingjobs
● Use of low-vibration paving breakersin road construction and mining
● Use of chipping hammers in stoneand steel working with low-vibrationhandle sleeves for chisel guides
● Use of power chainsaws with low-vibration handles in forestry
● Exclusive use of sharp tools andcorrection of unbalances at regularintervals
● Use of adhesives instead of riveting
● Design of foundry moulds requiringlittle cleaning effort
● Use of multiple screwdrivers
Generally speaking, preference shouldbe given to low-vibration technologies.*) Note: See national regulations
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Grip vibrations of hand-held machinesshould be kept at a minimum by themanufacturer by appropriate designmeasures.
Further advantages of low-vibration ma-chinery are reduced wear and tear andlower noise generation. In most cases,their products will show greater dimen-sional stability and precision.
Reduction ofwhole-body vibrations (WBV)
Road irregularities, e.g. on unsurfacedtracks, construction sites, factory accessroads, driveways etc. should be reducedor eliminated. Road ramps, bumps andpotholes should be repaired. In the caseof rail vehicles (cranes etc.), rail jointsthat might induce vibrations should beeliminated by welding or levelled, andconstruction site roads should be le-velled at regular intervals.
Depending on operating conditions andvehicle types preference should be givento spring-mounted driver’s seats orcabs. This might require consultationwith experts, who will, if necessary, per-form vibration measurements.
The seat suspension travel shouldbe reasonably limited in order not tounduly change the distance betweenthe driver, the steering wheel, controlsand pedals. Rubber cushions shouldbe mounted at the upper and lower endsof the suspension travel to avoid inten-sive shocks!
The driver’s seat can also contributeto vibration damping: The spring damp-ing system of the seat substructureshould be designed so as to keep thevibrations passed on to the driver at aminimum.
The springing must be adjustable – andactually adjusted! – to different bodyweights.
Drivers are particularly exposed towhole-body vibrations. Vehicle design,road conditions and driving speedare important factors influencing vibra-tion exposure, and the seat as theelement of transmission from thevehicle to the driver. This means thatvibration reduction can be effectedthrough appropriate action in all theseareas.
Technological measures to reduce vibra-tions include:● elastic coupling of loading devicessuch as shovels and lifting armsof wheel-loaders or agricultural ma-chinery mounted on the rear oftractors,
● hydraulic axle suspension with leveladjustment,
● cushioned driver’s cabs and● installation of driver’s seats withadjustable damping.
In the case of fork lift trucks the chassisis not spring-suspended for technicalreasons, so that the vehicle is only cush-ioned by the tyres. Accordingly, choiceof the right type of tyres is of particularimportance. Solid tyres transmit vibra-tions directly without damping them.For this reason tyres with integratedair chambers are being increasinglyused.
For all types of vehicles vibration re-duction largely depends on the rightchoice and adjustment of the seat. Thespring damping system of the seatsubstructure should be designed so asto keep the vibrations passed on to
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the driver at a minimum. In no caseshould the frequency of the seat bethe same as the excitation frequency,otherwise the vibrations would be in-creased. For this reason the seat mustbe adjustable to the driver’s bodyweight.
Only tested seats should be used invehicles, and the cushioning, dampingand upholstery of vehicle seats mustbe regularly serviced.
Alongside the most effective primarymeasures applied at the source of vibra-tions, secondary measures may alsohelp reduce vibration transmission andpropagation and in this way reducevibration exposure effectively.
In stationary machines the transmissionof vibrations to the human being canbe reduced by appropriate vibration in-sulation of the machine or the workplaceas a whole. Vibration insulation servesto reduce the transmission of machineforces to the supporting structures (e. g.floors and ceilings). For this purpose ma-chines are mounted on an oscillatingfoundation which, in turn, sits on insulat-ing materials.
In addition, the machine must be iso-lated from all parts of the buildingor other machines by elastic connec-tions such as pipe clamps, hoses, tex-tile connections, flexible boots or elasticpipe compensators to prevent transmis-sion of vibrations which may also bepropagated in the form of structure-bornesound.
In the case of heavy machines (e. g.eccentric presses) the oscillation founda-tion can be replaced by a load-distri-buting steel plate mounted on vibrationinsulators. In this way construction
costs for the foundation can be savedand the location of the machines canbe changed at will.
Low-vibration machines are less noisyand more wear-resistant and their pro-ducts will show greater dimensionalstability.
5. Technological and organisationalmeasures
Vibration hazards can also be diminishedby reducing exposure times throughchanges in work organisation. Workshould be organised in such a way asto keep the daily exposure periodbelow the recommended level so thatthey remain below the critical dailydose.
6. Personal protection
It may be pointed out that the protec-tion of human beings from mechanicalvibrations can be achieved by an appro-priate posture and by keeping grip andpressing forces as low as possible. Thisform of behaviour can be highly effec-tive, but requires considerable time fortraining and presupposes constant self-observation.
High-frequency vibration exposures (e. g.when working with grinding machi-nes) can be reduced by anti-vibrationgloves. Such gloves, however, requirethe worker to apply more grip forceto guide the hand tool with precision.On account of the large amplitude oflow-frequency vibrations such as occurin the operation of breakers, vibrationreduction by means of anti-vibrationgloves is not particularly effective.
Laboratory tests have shown that vibra-tions may even be increased when such
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gloves with air-filled damping cushionson the palms are used. It is there-fore advisable to check the data onthe damping properties provided bythe manufacturer (Look for the CE sym-bol).
Cold hands should be avoided duringexposure to vibrations, e. g. by meansof gloves or through warming-up pe-riods.
7. Vibration reductionprogramme
Following the transposition of the ECdirectives into national legislation employ-ers have to adopt state-of-the-art protec-tion measures to exclude vibration haz-ards or reduce them to a minimum. In sodoing, vibrations must be prevented orreduced as far as possible at source.Technological measures to reduce vibra-tions take priority over organisationalones.
The reduction programme aims at de-termining exposures, analysing theircauses and defining appropriate meas-ures.
Steps to be taken
● Determination of vibrationexposures
● Vibration reduction programme
● Determination of vibrationexposure values
● Comparison with actionand exposure limit values
● Cause analysis
● Comparison with state-of-the-arttechnology
● Choice of appropriate measures
● Drawing up a vibration reductionprogramme with list of prioritiesand timetable
7.1 Hand-arm vibration (HAV)reduction programme
If the action value A(8) = 2.5 m/s2 forhand-arm vibrations is exceeded theemployer has to prepare and implementa programme of technological andorganisational measures for the reduc-tion of vibration exposures.
The following steps are recommended:
Step 1:Determination of vibrationexposures (HAV)
● Can relevant informationbe obtained from manufacturers?
● Are data available in databases?
● Can comparable job descriptionsyield useful information?
● Are there any data for the equip-ment in question available in theliterature (data bases) and dothe conditions of use in the enter-prise correspond to those prevailingwhen the measurements weremade?
● Are any daily exposure valuesknown or can they be calculatedfrom vibration intensity dataand individual exposure times?
● Is there any need for additionalmeasurements?
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Step 2:Comparison with actionand exposure limit values (HAV)
● Is the action value for hand-armvibrations lower than A(8) = 2.5 m/s2?
● Is the measured value higher thanthe action value and lower than theexposure limit value?
● Is the exposure limit value ofA(8) = 5 m/s2 exceeded?
Step 3:Determination of the main sourcesof vibrations (HAV)
● Are there any particularly importantsources of vibration, i. e. individualjobs that cause particularly intensivevibrations (e.g. work with breakers)?
● Do certain tools or pieces ofequipment cause more intensivevibrations than others?
● Do they require high grip andpressing forces?
● Are certain jobs performed in un-favourable body postures (e.g. handsheld at unphysiological angles)?
● Are there any other environmentalfactors to be taken into considerationsuch as working in a cold environ-ment?
Step 4:Cause analysis (HAV)
● What are the causes of the highvibration values?
● Is the equipment old and possiblyworn down (e.g. defective gearmechanisms)?
● Are the tools used blunt orworn down?
● Are there no adequate decouplingor cushioning systems?
● Is the equipment serviced at regularintervals?
● Does the job require high grip andpressing forces?
Step 5:Comparison with state-of-the-arttechnology (HAV)
● Is the equipment up to currentstandards?
● Is there more modern equipmentthat would result in lower vibrationexposures?
● Are there any attachments availablethat would reduce the vibrationstransmitted to the operators?
● Are there any handles or ergonomi-cal handle designs (e.g. spring-loaded handles) that would improveworking conditions?
● Are the grips decoupled fromthe machine casing and/or is itpossible to correct unbalances?
● Is it possible to use grips withcushioning such as rubber sleeves?
● Are low-vibration tools such asspecial sanding discs used?
● Can process alterations resultin reducing exposures?
● Is it possible to reduce theextent of manual work with vibratingequipment?
Step 6:Selection of suitable measures (HAV)
● What measure would be capable ofreducing vibrations most effectively?
● Can it be implemented?
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● If this is impossible, what measurewould be second best?
● Can this measure be implemented?● How many workers would benefitfrom these reduction measures?
● Would certain jobs or groups of work-ers be excluded from these benefits?
● Will it be necessary to inform and/ortrain workers specifically for theimplementation of these measures?
Step 7:Prognosis (HAV)
● What is the expected effect of thereduction measures?
● Will the measures result in valueslower than the action value?
● Will the measures result in valueslower than the exposure limit value?
● Will it be necessary to resort toadditional measures side by side withthe measure in question?
● Will it be necessary to take furthermeasures?
Step 8:Drawing up the programme with a listof priorities and timetable (HAV)
● What steps have to be taken?● How much time will it take toimplement the individual measures?
● When can the first interim resultsbe expected?
● Who is responsible for whichimplementation step?
● By what deadline ought all measuresto be implemented?
● Is it possible to use anti-vibrationgloves in addition to the implementedmeasures?
Step 9:Checking the results (HAV)
● Have the measures beenimplemented correctly?
● What degree of vibration reductionhas been achieved?
● Has the predicted reduction beenachieved?
● Are the values achieved belowthe exposure limit value?
● Are the values achieved belowthe action value?
● Will it be necessary to make furtherimprovements?
● Are subsequent measurementsrequired for checking?
● Would additional vibrationreduction measures make senseor be necessary?
7.2 Whole-body vibration (WBV)reduction programme
Following the transposition of the ECdirectives into national legislation em-ployers have to adopt state-of-the-artprotection measures to exclude vibra-tion hazards or reduce them to a mini-mum. In so doing, vibrations must beprevented or reduced as far as possibleat source. Technological measures toreduce vibrations take priority over orga-nisational ones.
If the action value A(8) = 0.5 m/s2 forwhole-body vibrations is exceeded theemployer has to prepare and imple-ment a programme of technological andorganisational measures for the reduc-tion of vibration exposures.
The following steps are recommended:
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Step 1:Determination of vibrationexposures (WBV)
● Can relevant information be obtainedfrom manufacturers?
● Are data available in data bases?● Can comparable job descriptionsyield useful information?
● Are there any data for the equipmentin question available in the literature(data bases) and do the conditions ofuse in the enterprise correspond tothose prevailing when the measure-ments were made?
● Are any daily exposure valuesknown or can they be calculatedfrom vibration intensity dataand individual exposure times?
● Is there any need for additionalmeasurements?
Step 2:Comparison with actionand exposure limit values (WBV)
● Is the measured value for WBVlower than the action value?
● Is the measured value higherthan the action value and lower thanthe exposure limit value?
● Is the exposure limit valueexceeded?
Step 3:Determination of the main sourcesof vibrations (WBV)
● Are there any particularly importantsources of vibration, i.e. individualjobs that cause particularly intensivevibrations (e.g. high percentage ofdriving on cobblestone pavements,bumpy roads etc.)?
● Do certain machines or vehiclescause more intensive vibrations thanothers?
● Where are vibrations fairly low?
Step 4:Cause analysis (WBV)
● What are the causes of thehigh vibration values?
● Are the roads bumpy?
● Are there any kerbs, potholesetc. that have to be negotiatedby the vehicle?
● Are the seats equipped withappropriate cushioning or dampingsystems?
● Are the seats adjusted to the drivers’individual body weights?
● Are the vehicles serviced at regularintervals?
● Can driving times be reduced?
Step 5:Comparison with state-of-the-arttechnology (WBV)
● Are the vehicles and equipmentup to current standards?
● Are there any more modernvehicles or equipment that wouldresult in lower vibrationexposures?
● Are there any attachments availablethat would reduce the vibrationstransmitted to the operators?
● Are there any seats that wouldreduce vibrations more effectivelythan the current ones?
● Can road conditions be improvedby appropriate repairs?
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Step 6:Selection of suitable measures (WBV)
● What measure would becapable of reducing vibrations mosteffectively?
● Can it be implemented?● If this is impossible, what measurewould be second best?
● Can this measure be implemented?● How many workers would benefitfrom these reduction measures?
● Would certain jobs or groupsof workers be excluded from thesebenefits?
● Will it be necessary to inform and/ortrain workers specifically for theimplementation of these measures?
Step 7:Prognosis (WBV)
● What is the expected effect of thereduction measures?
● Will the measures result in valueslower than the action value?
● Will the measures result invalues lower than the exposure limitvalue?
● Will it be necessary to resort toadditional measures side by side withthe measure in question?
● Will it be necessary to take furthermeasures?
Step 8:Drawing up the programme with a listof priorities and timetable (WBV)
● What steps have to be taken?● How much time will it take toimplement the individual measures?
● When can the first interim resultsbe expected?
● Who is responsible for whichimplementation step?
● By what deadline ought all measuresto be implemented?
Step 9:Checking the results (WBV)
● Have the measures been implement-ed correctly?
● What degree of vibration reductionhas been achieved?
● Has the predicted reduction beenachieved?
● Are the values achieved belowthe exposure limit value?
● Are the values achieved below theaction value?
● Will it be necessary to make furtherimprovements?
● Are subsequent measurementsrequired for checking?
● Would additional vibrationreduction measures make sense orbe necessary?
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Annex 1
Implementation of workplacemeasurementsMeasurements are made in three dimen-sions, i.e. along the axes x, y and z.In the case of hand-arm vibrations, thevalues obtained are then used to calcu-late the vibration total value (vector),while for whole-body vibrations the indi-vidual directions are assessed separa-tely.Hand-arm measurements are particularlycomplex, especially since measurementshave to be made on both handles.Assessment is based on frequency-weighted accelerations and the daily ex-posure value A(8). Considerable import-ance attaches to workplace analysis anda representative record of activities (andparts thereof) undertaken in the course ofthe workday.
Performance of measurements (HAV)Hand-arm measurements are performedat the handle of the hand-held or hand-guided tool.
Fig. 1: Measuring HAV Fig. 2: Measuring WBV
For the purpose of measuring a speciallydesigned triaxial accelerometer is clamp-ed to the handle or glued to it.
Hand-arm vibrations are evaluated on thebasis of the vibration total value of thefrequency-weighted accelerations in allthree directions of vibration, which consti-tutes the vector sum of the values meas-ured in the three directions. It is essentialto perform the measurement in the courseof an operating sequence typical of theworkplace under consideration.
Performance of Measurements (WBV)Whole-boy vibration measurements are,for instance, performed on the driver’sseat of the vehicle under investigation.The triaxial accelerometer pad is attachedto the seat by means of an adhesive tape.Care should be taken to orientate the ac-celerometer pad correctly (x = chest toback, y = shoulder to shoulder, z = alongthe spine) and to adjust the seat setting tothe driver’s actual weight. The duration ofmeasurement depends on the usual dis-tance of travel in the course of the daily
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Exposure parameter calculators
A number of exposure parameter calcu-lators are available on the Internet. Theyare helpful for calculating averagesand presenting the results graphically,e. g. in the form of the “traffic-light rat-ing system“, where the green area standsfor results below the action value andthe red area for results that exceed theexposure limit value.
Evaluations and graphic presenta-tions may also take the form of expo-sure points, but the final result is notaffected by the method of presentationchosen.
Exposure parameter calculators areavailable from Ministries, supervisoryauthorities and equipment manufac-turers.
Note:In part, the red areas show differenc-es, since the transposition of the Euro-pean Directive “Vibrations“ into natio-nal legislations has not been effectedin a uniform way, for instance in re-spect of the stipulations regarding thez-direction in the case of whole-bodyvibrations.
operation of the vehicle and/or the type ofactivity in question and its “repetitive-ness”, but should in no case be less than15 minutes. Measurements should beperformed in the course of normal opera-tions so that they are representative of theactivity under consideration. All three ac-celeration values are recorded in thethree directions indicated above.
Whole-body vibrations are evaluated onthe basis of the highest effective valueof the frequency-weighted accelerationsin the three directions of measure-ment. Please note that the horizontalacceleration values have first to bemultiplied by a correction factor of 1.4.Since the exposure limit values are differ-ent for the vertical and horizontal direc-tions, the measurements have to beassessed separately.
x-axis aw = 1.4 awx
y-axis aw = 1.4 awy
z-axis aw = 1.0 awz
The data are then used to calculate thedaily vibration exposure value, taking intoaccount the actual duration of effectiveexposure.
21
Annex 2
Parameters forExposure Assessment
Assessment of whole-bodyvibrations (WBV)Whole-body vibrations are assessedon the basis of the highest effectivevalue for the frequency-weighted ac-celerations in the direction of the axes x,
y, and z (1.4 awx, 1.4 awy, awz – z-axisacceleration = along the spine).
Details can be gleaned from ISO 2631.Practical guidance and parameter calcu-lators will be found on the Internet.
Fig. 3 shows the frequency-weightedacceleration plotted against daily ex-posures.
Fig. 3: Frequency-weighted acceleration plotted against daily exposures(Source: ISO 2631/VDI-Richtlinie 2057-1)
0.5 1.0 2.0 4.0 8.0 16.0 24.0
10.0
m/s2
Fre
quen
zbew
erte
teB
esch
leun
igun
ga w
T�gliche Einwirkungsdauer Te in Stunden
5.0
2.5
1.6
1.130.900.800.64
0.45
0.25
0.1
Zone of increased health hazard in case of long-term exposure
� Assessed acceleration aw(8) = 0.45 m/s2� Assessed acceleration aw(8) = 0.80 m/s2
aw(8) = aw(e)Te8h����
Frequency-weightedaccelerationa w
Daily exposure Te in hours
Fig. 4: Vibration total value plotted against daily exposure(Source: ISO 5349/VDI-Richtlinie 2057-2)
22
10 30 50 100 300 480 1000
100
10
1
m/s2
Sch
win
gung
sges
amtw
erta
hv
T�gliche Einwirkungsdauer T in min
Note: The curve shown represents a daily exposure of ahv(8) of 2.5m/s2 for the purposeof prevention.
Assessment of hand-arm vibrations(HAV)Hand-arm vibrations are assessed onthe basis of the vibration total valuefor the frequency-weighted accelerationsof all three directions of vibration andthe vector calculated from these data,
vibration total value ahv. Details willbe found in ISO 5349. Practical guidanceand exposure parameter calculators areavailable on the Internet.
Fig. 4 shows the vibration total valueplotted against daily exposure.
Vibrationtotalvaluea w
Daily exposure time T in minutes
23
National Aspects
GeneralThe Directive "Vibrations“ (2002/44/EC)may be transposed into national legis-lation such as regulations etc. and adapt-ed to individual condition prevailing inthe member countries. This meansthat already existing rules, procedures,limit values and targets may remain inforce.
Accordingly, the above-mentioned Direc-tive contains various different para-meters such as frequency-weightedacceleration A(8) and a vibration dosevalue (V).
It is therefore possible to keep existingprevention values already in force, e.g.values for whole-body vibrations thatfocus in particular on vibrations in thez-direction.
24
National Contact Persons
The following ISSA International Sections on Prevention elaborated the brochure.They are also available for further information:
www.issa.intClick on “Prevention Sections” under “Quick Links”
ISBN 978-3-941441-52-1
ISSA Section forIron and Metal
c/o AllgemeineUnfallversicherungsanstaltOffice for InternationalRelationsAdalbert-Stifter-Strasse 651200 Vienna · AustriaFon: +43 (0) 1-33 111-558Fax: +43 (0) 1-33 111-469E-Mail: [email protected]
ISSA Section forElectricity
c/o BerufsgenossenschaftEnergie Textil ElektroMedienerzeugnisseGustav-Heinemann-Ufer 13050968 Köln · GermanyFon: +49 (0) 221 - 3778 - 6007Fax: +49 (0) 221 - 3778 - 196007E-Mail: [email protected]
ISSA Section forMachine and System Safety
Dynamostrasse 7-1168165 Mannheim · GermanyFon: +49 (0) 621-4456-2213Fax: +49 (0) 621-4456-2190E-Mail: [email protected]