Chapter47-NoiseTHENATUREANDEFFECTSOFNOISEAliceH.SuterThePervasiveNatureofOccupationalNoiseNoiseisoneofthemostcommonofalltheoccupationalhazards.IntheUnitedStates,forexample,morethan9millionworkersareexposedtodailyaverageA-weightednoiselevelsof85decibels(abbreviatedhereas85dBA).Thesenoiselevelsarepotentiallyhazardoustotheirhearingandcanproduceotheradverseeffectsaswell.Thereareapproximately5.2millionworkersexposedtonoiseabovetheselevelsinmanufacturingandutilities,whichrepresentsabout35%ofthetotalnumberofworkersinUSmanufacturingindustries.Hazardousnoiselevelsareeasilyidentifiedanditistechnologicallyfeasibletocontrolexcessivenoiseinthevastmajorityofcasesbyapplyingoff-the-shelftechnology,byredesigningtheequipmentorprocessorbyretrofittingnoisymachines.Butalltoooften,nothingisdone.Thereareseveralreasonsforthis.First,althoughmanynoisecontrolsolutionsareremarkablyinexpensive,otherscanbecostly,especiallywhentheaimistoreducethenoisehazardtolevelsof85or80dBA.Oneveryimportantreasonfortheabsenceofnoisecontrolandhearingconservationprogrammesisthat,unfortunately,noiseisoftenacceptedasa“necessaryevil”,apartofdoingbusiness,aninevitablepartofanindustrialjob.Hazardousnoisecausesnobloodshed,breaksnobones,producesnostrange-lookingtissue,and,ifworkerscanmanagetogetthroughthefirstfewdaysorweeksofexposure,theyoftenfeelasthoughtheyhave“gotused”tothenoise.Butwhathasmostlikelyhappenedisthattheyhavestartedtoincuratemporaryhearinglosswhichdullstheirhearingsensitivityduringtheworkdayandoftensubsidesduringthenight.Thus,theprogressofnoise-inducedhearinglossisinsidiousinthatitcreepsupgraduallyoverthemonthsandyears,largelyunnoticeduntilitreacheshandicappingproportions.Anotherimportantreasonwhythehazardsofnoisearenotalwaysrecognizedisthatthereisastigmaattachedtotheresultinghearingimpairment.AsRaymondHétuhasdemonstratedsoclearlyinhisarticleonrehabilitationfromnoise-inducedhearinglosselsewhereinthisEncyclopaedia,peoplewithhearingimpairmentsareoftenthoughtofaselderly,mentallyslowandgenerallyincompetent,andthoseatriskofincurringimpairmentsarereluctanttoacknowledgeeithertheirimpairmentsortheriskforfearofbeingstigmatized.Thisisanunfortunatesituationbecausenoise-inducedhearinglossesbecomepermanent,and,whenaddedtothehearinglossthatnaturallyoccurswithageing,canleadtodepressionandisolationinone’smiddleandoldage.Thetimetotakepreventivestepsisbeforethehearinglossesbegin.TheScopeofNoiseExposureAsmentionedabove,noiseisespeciallyprevalentinthemanufacturingindustries.TheUSDepartmentofLaborhasestimatedthat19.3%oftheworkersinmanufacturingandutilitiesareexposedtodailyaveragenoiselevelsof90dBAandabove,34.4%areexposedtolevelsabove85dBA,and53.1%tolevelsabove80dBA.Theseestimatesshouldbefairlytypicalofthepercentageofworkersexposedtohazardouslevelsofnoiseinothernations.Thelevelsarelikelytobesomewhathigherinlessdevelopednations,whereengineeringcontrolsarenotusedaswidely,andsomewhatlowerinnationswithstrongernoisecontrolprogrammes,suchastheScandinaviancountriesandGermany.Manyworkersthroughouttheworldexperiencesomeveryhazardousexposures,wellabove85or90dBA.Forexample,theUSLaborDepartmenthasestimatedthatnearlyhalfamillionworkersareexposedtodailyaveragenoiselevelsof100dBAandabove,andmorethan800,000tolevelsbetween95and100dBAinthemanufacturingindustriesalone.Figure47.1ranksthenoisiestmanufacturingindustriesintheUnitedStatesindescendi...
优质VIP
