HeatPproductivity_NASA.pdf

NASACR-1205-1,ACompendiumofHumanResponsestotheAerospaceEnvironment.*Thereportshowsthatwhenin-planttemperaturesriseover85,outputdropsby18%andaccuracysuffersfroma40%increaseinerrors.Productivitylossesfromhightemperaturesmaybedocumentedbyyourownproductionrecords.EffectiveTemp.7580859095100105LossinOutput3%8%18%29%45%62%79%LossinAccuracyNegligible5%40%300%700%-*EffectiveTemperatureisthecombinedeffectoftemperature,humidity,andairmotiononthebody.*StudyforNASA.ComfortConditioningthePlantwithEvaporativeCoolingPlantEngineeringJuly8,1976Pg76JosephMargEvaporativeAirConditioningHandbookJohnWatt,PEandWillBrownPE3rdEditionPg201U.S.DepartmentofLaborProgramHighlightsFactSheetNo.OSHA95-16PROTECTINGWORKERSINHOTENVIRONMENTSManyworkersspendsomepartoftheirworkingdayinahotenvironment.Workersinfoundries,laundries,constructionprojects,andbakeries-tonameafewindustries-oftenfacehotconditionswhichposespecialhazardstosafetyandhealth.HEATSTRESSCAUSESBODYREACTIONSFourenvironmentalfactorsaffecttheamountofstressaworkerfacesinahotworkarea:temperature,humidity,radiantheat(suchasfromthesunorafurnace)andairvelocity.Perhapsmostimportanttothelevelofstressanindividualfacesarepersonalcharacteristicssuchasage,weight,fitness,medicalconditionandacclimatizationtotheheat.Thebodyreactstohighexternaltemperaturebycirculatingbloodtotheskinwhichincreasesskintemperatureandallowsthebodytogiveoffitsexcessheatthroughtheskin.However,ifthemusclesarebeingusedforphysicallabor,lessbloodisavailabletoflowtotheskinandreleasetheheat.Sweatingisanothermeansthebodyusestomaintainastableinternalbodytemperatureinthefaceofheat.However,sweatingiseffectiveonlyifthehumiditylevelislowenoughtopermitevaporationandifthefluidsandsaltslostareadequatelyreplaced.Ofcoursetherearemanystepsapersonmightchoosetotaketoreducetheriskofheatstress,suchasmovingtoacoolerplace,reducingtheworkpaceorload,orremovingorlooseningsomeclothing.Butifthebodycannotdisposeofexcessheat,itwillstoreft.Whenthishappens,thebodyscoretemperaturerisesandtheheartrateincreases.Asthebodycontinuestostoreheat,theindividualbeginstoloseconcentrationandhasdifficultyfocusingonatask,maybecomeirritableorsickandoftenlosesthedesiretodrink.ThenextstageIsmostoftenfaintinganddeathispossibleifthepersonisnotremovedfromtheheatstress.HEATDISORDERSHeatstroke,themostserioushealthproblemforworkersinhotenvironments,iscausedbythefailureofthebodysinternalmechanismtoregulateitscoretemperature.Sweatingstopsandthebodycannolongerriditselfofexcessheat.Signsinclude(1)mentalconfusion,delirium,lossofconsciousness,convulsionsorcoma；(2)abodytemperatureof106degreesForhigher；and(3)hotdryskinwhichmaybered,mottled,orbluish.Victimsofheatstrokewilldieunlesstreatedpromptly.Whileawaitingmedicalhelp,thevictimmustberemovedtoacoolareaandhisorherclothingsoakedwithcoolwater.Heorsheshouldbefannedvigorouslytoincreasecooling.Promptfirstaidcanpreventpermanentinjurytothebrainandothervitalorgans.Heatexhaustionresultsfromlossoffluidthroughsweatingwhenaworkerhasfailedtodrinkenoughfluidsortakeinenoughsaltorboth.Theworkerwithheatexhaustionstillsweatsbutexperiencesextremeweaknessorfatigue,giddiness,nausea,orheadache.Theskinisclammyandmoist,thecomplexionpaleorflushed,andthebodytemperaturenormalorslightlyhigher.Treatmentisusuallysimple:thevictimshouldrestinacoolplaceanddrinkwateroranelectrolytesolution(abeverageusedbyathletestoquicklyrestorepotassium,calcium,andmagnesiumsalts).Severecasesinvolvingvictimswhovomitorloseconsciousnessmayrequirelongertreatmentundermedicalsupervision.Heatcramps,painfulspasmsofthemuscles,arecausedwhenworkersdrinklargequantitiesofwaterbutfailtoreplacetheirbodiessaltloss.Tiredmuscles-thoseusedforperformingthework-areusuallytheonesmostsusceptibletocramps.Crampsmayoccurduringorafterworkinghoursandmayberelievedbytakingliquidsbymouthorsalinesolutionsintravenouslyforquickerrelief,ifmedicallydeterminedtoberequired.Fainting(heatsyncope)maybeaproblemfortheworkerunacclimatizedtoahotenvironmentwhosimplystandsstillintheheat.Victimsusuallyrecoverquicklyafterabriefperiodoflyingdown.Movingaround,ratherthanstandingstill,willusuallyreducethepossibilityoffainting.Heatrash,alsoknownaspricklyheat,mayoccurinhotandhumidenvironmentswheresweatisnoteasilyremovedfromthesurfaceoftheskinbyevaporation.Whenextensiveorcomplicatedbyinfection,heatrashcanbesouncomfortablethatitinhibitssleep,impedesaworkersperformance,orevenresultsintemporarytotaldisability.Itcanbepreventedbyrestinginacoolplaceandallowingtheskintodry.PREVENTINGHEATSTRESSMostheat-relatedhealthproblemscanbepreventedortheriskofdevelopingthemreduced.Followingafewbasicprecautionsshouldlessenheatstress.1.Avarietyofengineeringcontrolsincludinggeneralventilationandspotcoolingbylocalexhaustventilationatpointsofhighheatproductionmaybehelpful.Shieldingisrequiredasprotectionfromradiantheatsources.Evaporativecoolingandmechanicalrefrigerationareotherwaystoreduceheat.Coolingfanscanalsoreduceheatinhotconditions.Eliminatingsteamleakswillalsohelp.Equipmentmodifications,theuseofpowertoolstoreducemanuallaborandpersonalcoolingdevicesorprotectiveclothingareotherwaystoreducethehazardsofheatexposureforworkers.2.Workpracticessuchasprovidingplentyof,drinkingwater-asmuchasaquartperworkerperhour-attheworkplacecanhelpreducetheriskofheatdisorders.Trainingfirstaidworkerstorecognizeandtreatheatstressdisordersandmakingthenamesoftrainedstaffknowntoallworkersisessential.EmployersshouldalsoconsideranindividualworkersphysicalconditionwhendetermininghisorherfitnessforworkingInhotenvironments.Olderworkers,obeseworkersandpersonnelonsometypesofmedicationareatgreaterrisk.3.Alternatingworkandrestperiodswithlongerrestperiodsinacoolareacanhelpworkersavoidheatstress.Ifpossible,heavyworkshouldbescheduledduringthecoolerpartsofthedayandappropriateprotectiveclothingprovided.Supervisorsshouldbetrainedtodetectearlysignsofheatstressandshouldpermitworkerstointerrupttheirworkiftheyareextremelyuncomfortable.4.Acclimatizationtotheheatthroughshortexposuresfollowedbylongerperiodsofworkinthehotenvironmentcanreduceheatstress.Newemployeesandworkersreturningfromanabsenceoftwoweeksormoreshouldhavea5-dayperiodofacclimatization.Thisperiodshouldbeginwith50percentofthenormalworkloadandtimeexposurethefirstdayandgraduallybuildingupto100percentonthefifthday.5.Employeeeducationisvitalsothatworkersareawareoftheneedtoreplacefluidsandsaltlostthroughsweatandcanrecognizedehydration,exhaustion,fainting,heatcramps,saltdeficiency,heatexhaustion,andheatstrokeasheatdisorders.Workersshouldalsobeinformedoftheimportanceofdailyweighingbeforeandafterworktoavoiddehydration.Safetyisamajoreconomicconsiderationinallworkingareas.Safeworkingconditionsareimportantinkeepinginsurancecostsdownandavoidingemployeedisruptions.Thehot,uncomfortableworkerismoreliabletoignoregoodsafetypracticeandallowaccidentcausingsituationstooccur.HeatStressrelatedproductivitylossesduetohightemperaturesinyourplantareprobablydocumentedbyyourownrecords.Accuracyissimilarlyaffectedastemperaturesabove85degreescausea300%increaseinerrors.LowMoralecausedbyanuncomfortableworkenvironmentresultsintardiness,absenteeism,andturnover.Thesummerincreaseinnegativeemployeereactionsduetoheatstressisalsodocumentedthroughproductionrecords.Vacantworkstationsresultinloweredefficiency,inovertimepaidtomeetschedules,andinhiringandtrainingcostsforreplacements.HealthFactorsrelatingtoheatstressintheworkingenvironmentisanincreasingconcernofregulatoryagencies.TheNationalInstituteofOccupationalSafety&Health(NIOSH)hasdevelopedapreliminarystandardforallowableheatstresslevels.Thestandarddefinesenvironmentaltemperaturerequirementsandwork-time/rest-timepercentage