Chapter56-AccidentPreventionINTRODUCTIONJormaSaariAccordingtoInternationalLabourOfficestatistics,120millionoccupationalaccidentsoccurannuallyatworkplacesworldwide.Ofthese,210,000arefatalaccidents.Everyday,morethan500menorwomendonotcomehomebecausetheywerekilledbyaccidentsatwork.Thesearedramaticnumberswhichdrawfairlylittlepublicattention.Consideringthefactthataccidentstakeaconsiderableeconomictollfromnations,companiesandindividuals,accidentsdonotgetmuchpublicity.Fortunatelytherearepeopleworkingwithasenseofpurpose,oftenbehindthescenes,towardsunderstandingandmanagingsafetyandaccidentpreventionbetter,andtheireffortshavenotbeenwasted.Ourunderstandingofaccidentpreventionandsafetyisonafarhigherlevelthaneverbefore.Manyworld-classresearchersandsafetypractitionerssharethisnewknowledgewithusthroughtheirarticlesinthisEncyclopaedia.Duringthepasttwentydecades,knowledgeaboutaccidentshasevolvedconsiderably.Wehaveleftbehindthesimplisticmodelofdividingbehaviourandconditionsintotwocategories:safeorunsafe.Therigidbeliefthatanyactivitycanbeplacedintoeithercategoryhasbeenputasideasmoresophisticatedsystemicmodelshavebeendevelopedandproveneffectiveinmanagingsafety.Theimportantobservationisthattwosafeconditionswhichbythemselvesaresafe,maynotbesafetogether.Workersaretheconnectinglink,astheirbehaviourchangesaccordingtotheenvironmentandtheirphysicalsurroundings.Asanexample,powersawscausedmanyaccidentswhentheycameintouseinthe1960sduetoahazardknownas“kickback”,whichtakestheoperatorbysurprisewhenthechain-sawbladeshitabranch,knotorharderpointinwood.Kickbackkilledandinjuredhundredsofpeoplebeforeaguardwasinventedtoprotecttheoperator.WhenSwedenimplementedregulationsrequiringthekickbackguard,thenumberofpowersawinjurieswentdownfrom2,600in1971to1,700in1972.Thiswasamajorbreakthroughinpowersawaccidentprevention.Everyuserofpowersawsknowsfrompersonalexperiencethatthisnoisy,vibratingandobviouslysharpcuttingtoolappearstobeverydangeroustouse,andthebeginneroperatorisverycautious.However,afterhoursofexperienceoperatorslosetheirsenseofanyhazardandstarthandlingthesawlesscarefully.Thekickbackguardmayproduceasimilareffect.Operatorswhoknowkickbackispossibletrytoavoidit.Whenoperatorsknowthatthereisamechanicaldevicepreventingthesawfromhurtingthemineventofkickback,theybecomelesscautious.Inanotherforestryindustrychain-sawexample,studieshaveshownthatlegprotectionmakesworkerslesscarefulandtheyexposethemselvesmoreoftentokickbacks,becausetheybelievetheyareprotected.Despitethefactthatkickbackprotectionhashelpedpreventinjuries,themechanismisnotstraightforward.Eveniftheseprotectivearrangementshavebeensuccessful,inthefinalanalysistheireffectsdonothavealinearrelationshipwithsafety.Twosafeconditions,kickbackguardandlegprotection,donotdoublethesafety.Thenormalarithmeticofoneplusoneequalstwo(1+1=2),doesnotapplyinthiscase,asoneplusonemakeslessthantwo.Fortunately,oneplusone(1+1)makesmorethanzeroinsomecases.Inothercases,however,thesummayevenbenegative.Thesearephenomenawhichsafetypractitionershavestartedtounderstandbetterthanbefore.Thesimpledivisionofbehavioursandconditionsintosafeandunsafedoesnotleadveryfartowardprevention.Thecreditforprogresshastobegiventosystemsmanagement.Afterunderstandingthathumans,theirtasks,theirequipmentandtheenvironmentmakeupadynamicsystem,wehavemadeconsiderableprogresstowardsmoreeffectiveaccidentprevention.Thefol...
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