ASHRAE 室內(nèi)環(huán)境指導(手冊)

PublicReviewDraft_____________________________________ASHRAE?GuidelineProposedNewGuideline10,CriteriaforAchievingAcceptableIndoorEnvironmentsFirstPublicReview(May2005(CompleteDraftforFullReviewThisdrafthasbeenrecommendedforpublicreviewbytheresponsibleprojectcommittee.Tosubmitacommentonthisproposednewguideline,usethecommentformandinstructionsprovidedwiththisdraft.Thedraftissubjecttomodificationuntilitisapprovedforpublicationbytheresponsibleprojectcommittee,theASHRAEStandardsCommittee,andtheBoardofDirectors.ThecurrenteditionofanyguidelineorstandardmaybepurchasedfromtheASHRAEBookstore@http://www/orbycalling404-636-8400or1-800-527-4723(forordersintheU.S.orCanada.Theappearanceofanytechnicaldataoreditorialmaterialinthispublicreviewdocumentdoesnotconstituteendorsement,warranty,orguarantybyASHRAEofanyproduct,service,process,procedure,ordesign,andASHRAEexpresslydisclaimssuch.?March30,2005.ThisdraftiscoveredunderASHRAEcopyright.PermissiontoreproduceorredistributealloranypartofthisdocumentmustbeobtainedfromtheASHRAEManagerofStandards,1791TullieCircle,NE,Atlanta,GA30329.Phone:404-636-8400,Ext.1125.Fax:404-321-5478.E-mail:standards.section@.AMERICANSOCIETYOFHEATING,REFRIGERATINGANDAIR-CONDITIONINGENGINEERS,INC.1791TullieCircle,NEAtlantaGA30329-2305(Thisforewordisnotpartofthisguideline.Itismerelyinformativeanddoesnotcontainrequirementsnecessaryforconformancetotheguideline.FOREWORDThisguidelinefocusesonthermalcomfort,indoorairquality,andtheinteractionsbetweentheseenvironmentalconditionsastheyaffectthe“acceptability”oftheindoorenvironment.Inaddition,buttoalesserextent,italsoaddressesmechanicalenergy(includingnoiseandvibrationandelectromagneticradiation(includingenvironmentallighting,ultravioletandinfraredradiationasimportantfactorsaffectingtheacceptabilityoftheindoorenvironment.Theguidelineisintendedtoprovidethereader/useroftheguidelinewithbackgroundonthegenesisoftheguidelineandthecurrentstateofknowledgeonachievingacceptableindoorenvironments.Itistheintentionofthecommitteethatthisguidelinepresentthebestguidancethatexpertscanofferatpresent.Currentknowledgeoninteractionsbetweenandamongfactorsthatmostaffectoccupantsofindoorenvironmentsislimited.Therefore,thisguidelinerepresentsapreliminaryeffortatdefiningordescribingcriteriaforachievingacceptableindoorenvironments.Theguidelinepresentsabroadoverviewofthesubjectwithoutextensivedetails.Thisisappropriategiventhestateofknowledgeoninteractionsamongenvironmentalfactors.TheguidelineprojectcommitteebelievestheguidelinewillcallattentiontothesignificanceofinteractiveeffectsindeterminingtheacceptabilityofanyindoorenvironmentoranycombinationofindoorenvironmentalconditionsanditslimitationsThisguidelineisintendedforbuildingdesignerprofessionals(architects,engineers,spaceplanners,interiordesigners,aswellasforbuildinginvestigators,buildingscientists,andotherswhomaydeterminepolicyorfundingforbuildingdevelopmentorbuildingenvironmentalresearch.Therearemanyimportantfactorsthatdeterminetheacceptabilityoftheindoorenvironmentthathavenotbeenidentifiedoraddressedinthisdocument.Hopefully,futureversionsofthisguidelinewillincludemoredetailsontheserelatedfactors.NotetoReviewers:Thispublicreviewdraftisbeingissuedwiththeexpectationthattherewillbeconsiderablevaluableinputfromthecommenters.Theprojectcommitteeisawarethatthedocumentisnotreadyforpublicationbutwishestoobtaincommentsandsuggestionsfromabroadergroupofreviewersbeforerevisingandballotingitforpublication.CRITERIAFORACHIEVINGACCEPTABLEINDOORENVIRONMENTS1PURPOSETospecifyindoorenvironmentalcriteriathatareacceptabletohumanoccupantsandareintendedtominimizethepotentialforadversehealtheffects.2SCOPE2.1Thisguidelineprovidescriteriaforachievingacceptableindoorenvironments,addressingtheinteractionsamongthermalcomfort,indoorairquality,soundandvibration,andnon-ionizingelectromagneticradiation(includingvisiblelight.2.2Thisguidelineappliestothedesign,construction,commissioning,operationandmaintenanceofbuildings.2.3Thisguidelineappliestoallindoororenclosedspacesthatpeoplemayoccupy,except:(aareasofbuildingsintendedprimarilyformanufacturingorforcommercialorindustrialprocessing,(bsingleandmultifamilyresidentialbuildingsofthreeorfewerstoriesabovegrade,and(cbuildingsoffewerthan100ft2ofgrossfloorarea.3DEFINITIONSacceptableindoorenvironment:Acceptabilityofanindoorenvironmentisthedeterminationofanyaffectedpartythattheenvironmentissuitableforoccupancyandthepurposesoftheintendedoccupancy.Note:Acceptabilityisnotidenticalwiththesatisfactionofany,most,oralloccupants,whichwouldgenerallyrequireasomewhathigherlevelofenvironmentalquality.Ultimately,acceptabilitymustbedefinedbytheprocessusedtodetermineitaswellasbytheindividualsselectedtomaketheevaluations,assessments,orjudgmentsthatarepartoftheprocess.criteria:Asusedinthisguideline,criteriareferstostandards,rules,ortestsonwhichjudgmentsordecisionscanbebased.Specifically,itreferstothebasisofjudgment(e.g.,‘health’,aparticularhumanresponse(e.g.,fewerthan20%dissatisfied,anenvironmentalparameter(e.g.,temperatureoraspecificvalueofthatparameter(e.g.,21°C.]factor:Thetermsidentifyingthemajoraspectsoftheindoorenvironmentaddressedinthisguidelineareclassifiedtoas“factors,”"categories,"or"environmentalcomponents."Thefourfactors–indoorairquality,thermalenvironment,noise,andlight--arewidelyregardedasthemajorcategoriesforclassifyingdifferentaspectsoftheindoorenvironment.Manyseparateaspectsoftheenvironmentcombinetoformthelight,airquality,acousticandthermalconditionsoftheindoorenvironment.Note:Occupantexperienceofandresponsetotheindoorenvironmentmayalsobeaffectedstronglybyavarietyofotherfactors.Althoughmostoftheseareconsideredsubjectiveandmanyaredifficulttocharacterizequantitatively,theymayevenbedominantfactorsinindividualreactionstoaspace.Thesecharacteristicsorfactorsinclude,amongothers,thefollowing:?densityandproximityofotheroccupants,?spatialqualities(volume,shape,?presenceofwindows/views,activities,?locationandidentityofentrances/exits?“wayfinding”signsorclues–characteristicsoftheenvironmentthatenableoccupantstoascertaintheirlocationinrelationtootherpartsofthebuildingandtothesurroundingenvironment?aestheticqualitiesandcharacteristicsWhilethesefactorsarenotaddresseddirectlyinthisguideline,usersoftheguidelineshouldbeawarethatoneormoreofthesefactorscanhavesignificantorevendominanteffectsontheacceptabilityoftheindoorenvironmentalqualitynomatterwhatthecharacteristicsareofthemajorfactorsaddressedherein.indoorenvironments:Asusedherein,thistermreferstoenclosed,non-industrialbuildings.[Notetopublicreviewers:Pleaseidentifyanyothertermsthatyoubelieveneedtobeidentifiedbysubmittingapublicreviewcommentonthisguideline.]4INTRODUCTIONTOTHEFACTORSANDTHEIRINTERACTIONSNoaspectoftheindoorenvironmentisunrelatedtoorindependentfromtheotheraspects.Butthestrengthandsignificanceofthelinkagesandinteractionsforacceptabilityoftheindoorenvironmentarehighlyvariable.ThetwofactorsofmajorconcerntoASHRAEmembersandothersrelyingonASHRAEforguidanceareindoorairqualityandthermalconditions.Thereisconvincingevidenceoftheinteractionsbetweenthesefactorsanditisreasonablyclearwhatabuildingdesigneroroperatorshouldknowinordertoaddresstheinteractions.Someinteractionsbetweenenvironmentallightingandenvironmentalsoundwiththermalconditionsandwithindoorairpollutionhavealsobeeninvestigated,buttheimplicationsfordesignersarelessclear.Inallcases,achievingacceptableindoorenvironmentsrequiresthatdesignersaddresstheinteractions,whichinturnrequiresdesignerstoconsidertrade-offsbetweenandamongvariousimpactsandtheirmitigations.4.1IntroductiontoIndoorEnvironmentalFactorsIndoorenvironmentalfactorshavebothphysicalandpsychologicaleffectsonoccupants.Occupants’perceptionoftheenvironment(forexampleodororglarecanstronglyinfluencethephysiologicalresponse.Humanresponsestoindoorenvironmentalfactorsarehighlyvariable.Sensitivitytoodor(andpossiblyothereffectsofchemicalsmayvarybyafactorof10,000ormorebetweentwoindividuals.Theconcentrationsofchemicalsintheaircaneasilyvarybyfactorsof10,000betweenbuildingsorevenatdifferenttimesinthesamebuilding.Thus,therangeofresponsesofawiderangeofindividualstoawiderangeofcommonly-occurringenvironmentalconditionscanbeexpectedtobeverylarge.Whenthefullrangeofenvironmentalconditionsisconsideredandthewaytheseconditionsinteract,itisimpossibletoimagineallofthepossiblecombinationsofconditionsthatcanexist.Thediversityofconditionsthatactuallyoccurisbeyondpracticallimitsforprovidingpreciseguidance.Wetendtofocusourdesigneffortsandourstandardsandguidelinesonthemostprominentfactorsandonthoseoverwhichwehavesomedegreeofcontrol.Designforgoodindoorenvironmentalqualityaimstopreventoccupantdiscomfort,irritation,andillness;tomeetoccupantneeds;andtosupportoccupantactivities.Building-relateddisease,symptoms,discomfort,andirritationcanresultfromeitherindoorairorotherindoorenvironmentalconditions.Thereisevidencethatmanysuchhumanresponsescanbecausedbynoise,inadequateorpoorqualitylighting,lackofprivacyorcontrol,andotherenvironmentalfactorsknowntocausesuchsymptomreportsandcomplaints.Whenoneormoreoftheseenvironmentalfactorsisatvaluesneartooroutsideacceptedguidelinevaluesorlimits,thelikelihoodofanoccupantbecominguncomfortable,irritated,orillincreases.Therefore,itisimportanttoidentifyallcriticalenvironmentalvariables,tounderstandtherelationshipsbetweenthem,andtomakedesigndecisionsfullycognizantoftheinterdependent,dynamicrelationshipsbetweenindoorenvironmentalvariables(23,24.Itisalsopossiblethattwofactorsoutsidetherangedefinedasacceptablecanoffseteachothertomaketheenvironmentmoreacceptable.Whereanodorantispresentintheair,forexample,loweringthetemperaturemightmakeconditionsacceptable.Mostpeoplearewillingtotoleratesomediscomfortrelatedtooneenvironmentalfactorinordertoreduceanotheronethatwasdeemedintolerableor,tousethetermsofthisguideline,unacceptable.Bothenvironmentalfactorsandpsychologicalfactorsaffectindoorenvironmentalacceptabilityasfollows:a.Perceptionoftheenvironment:Environmentalfactorsaffectthehumanbodydirectlywhileperceptionofthecharacteristicsoftheenvironmentaffecttheinterpretationofthebody’sresponseorevencausephysiologicalresponsestotheenvironment.b.Perceptionoftheimpactsoftheenvironmentonanoccupant:Perceptionoftheimpactsoftheenvironmentonanoccupant’sbodyimpacttheoccupantresponse.Whethertheindividualcorrectlyconnectstheperceptionoftheimpactstoanactualcauseintheenvironmentornot,perceptionoftheimpactcanmodifyinterpretationoftheoccupantsinterpretationofandresponsetotheeffectsorsymptomsresultingfromotherexposuresorexperiences.Fearaboutapotentialhazard,forexample,changesthebody’sdefensesagainsttheperceivedhazardaswellasotherenvironmentalinsultsthatmightbepresent.Toillustrate,considerthecommonsymptom,headache.Peopletendtoblameheadachesonsomethingthattheyareawareiscausingthemstress,eitherphysicalorpsychological.Infactitcanbecausedbyeitherorbothatthesametime.Headachescanresultfromglare,noise,aircontaminants,orthermalconditionsaswellasfrompsychologicalandsocialfactorsandconditionssuchasanxiety,stressfulinterpersonalrelationships,orstressfulwork.Stresscanexacerbatetheeffectsofalmostanyenvironmentalfactorandevencauseotherwiseharmlessconditionstoaffectoccupanthealth,comfort,andwell-being.4.2BroadCategoriesofEnvironmentalFactorsandModifiersAlthoughtheremaybesomeoverlapamongenvironmentalfactors,theycanbeclassifiedinfourbroadcategories.1Chemical,2Physical,3Biological,and4Psychological.Eachcategorylistedabovehasmanysub-categoriesandmanyexamplescanbefoundineachoftheseofinteractionsandtheircombinedeffectswithimportantenvironmentalandpersonalfactors(1.Manyauthorsidentifysocialandinstitutionalfactorsseparatelyfrompsychologicalfactors(2.Thepsychologicalfactorscanbebrokendownintoperceptionoftheenvironment,perceptionoftheenvironmentalimpactonoccupants,experienceoftheenvironmentconditions,andexperienceoftheeffectsofenvironmentalfactors(3,4.Socialandinstitutionalfactorsmediatehumanresponsesthroughpsychologicalmechanisms-psycho-physicalandperceptual/experiential(4.AmoredetailedlistingoftheimportantfactorsintheindoorenvironmentisprovidedinTable1.Table1.Environmentalfactorstowhichthebodyresponds(24CHEMICALOrganicgasesandvaporsInorganicgasesandvaporsPHYSICALThermalfactors:(Temperature,Airvelocity,RadiantasymmetryMoistureElectromagneticenergy(Visiblelight,Ultravioletlight,Infraredradiation,Cosmicradiation,Extremelylowfrequency,andIonizingradiationElectrostaticfieldsMechanicalenergy(NoiseandVibrationBIOLOGICALTypesoforganisms:(Viruses,Bacteria,Fungi,Arthropods,etc.Status:(ViableorNon-viableEffects:(Infectiousagents,Allergens,Odorants,AsthmagenicsPSYCHOLOGICALEmotion:(Happiness,Joy,Anxiety,Fear,Anger,Fright,etc.Perception(Environment,EffectofEnvironment,Personal-responseProcesses:(Vision,Hearing,OdorPerception,Touch,Irritation,Itching?????????????????????????????????????Thehumanbodyintegratesitsresponsestoalltheenvironmentalfactorstowhichitisexposed:Inadditiontotheenvironmentalfactors,personalfactorscanaffectboththeenvironmentalimpactsonthebodyandtheoccupantresponse.Forexample,clothingaffectstheconvective,conductive,andradiantheattransfertherebyaffectingthermalcomfort.Recentandcurrentactivityandfoodconsumptionaffectsmetabolicratewhichinturnaffectsthermalbalanceandcomfort.Thehumanbody’sresponsetothetotalenvironmentisanintegratedone(5,6.Thereareseveralpossibleoutcomesofmultipleexposuresduetothehumanresponsetotheinteractionsamongtheexposuresoramongtheresponses.Thecombinedeffectoftheseexposuresmaybeanenhancement,diminution,ornoeffectsdependingonthecombination(23.Theresultsofinteractionsincludethefollowing:?Independent:nointeraction.?Antagonistic:onecounteractstheother.?Prophylactic:oneprotectsagainsttheeffectofanother.?Additive:theyactasthoughindependentbutobtaintheirseparateeffects.?Cumulative:overtime,additive.?Synergistic:effectofinteractionisgreaterthanadditive.4.3CriteriaforAchievingAcceptableIndoorEnvironmentsThecriteriarecommendedinmoststandardsandguidelinesforindoorenvironmentaldesignvaluesarederivedfromlaboratoryandfieldstudiesthattypicallyevaluateonlyasmallsub-setofenvironmentalconditions.Verylittleresearchhasbeendonetoinvestigatetheimpactsofthefullrangeofenvironmentalvariablesonoccupantsatisfaction,andsuchinvestigationsareextremelycomplexandcostly.Therefore,therecommendedcriteriaarenecessarilylimitedbytheavailabilityofreliabledata.However,thebuildingdesignermustaddressimportantinteractionsamongenvironmentalvariablesthatarelikelytoaffectoveralloccupantcomfort,health,andwell-being.Theuserofindoorenvironmentalguidelinesshouldnotassumethatmeetingeachseparatecriterionorseparatesetsofcriteriawillresultinthesatisfactionlevelachievedwhenonlyonevariableorsetofvariablesisaddressed.(94.3.1LimitstoRelianceonExistingStandardsandPreviousGuidelinesBecauseofthepotentialinteractionsamongfactorsandtheircombinedeffectsonthediversepopulationofbuildingoccupants,evenwherethedesignconformstoallstandardsandguidelinesforthefourseparatemajorenvironmentalfactorcategories,interactionsamongthefactorscanactuallyresultinunacceptableindoorenvironmentalquality.Forexample,anodorthatmaybeacceptablewhenthermalconditionsarecoolanddrymaybeannoyingorevensickeningwhenthermalconditionsarewarmandhumid.Particlesthatmaynotbeannoyingwhenhumidityisatnormallevelsmaybeirritatingtotheeyesorupperrespiratorytractwhenhumidityisverylow.Thermalconditionsthatmaybetolerableinanotherwiseacceptableworkorschoolsettingmaynotbetoleratedwhentheworkerorstudentisunhappywiththeirsupervisororteacherorwhentheyarestrugglingtocompleteanassignment.Design/constructionsolutionstocontroloneenvironmentalvariablemayresultinproblemsinanothervariable.Anillustrativecaseisthatofacousticcontrolwhere“fleecy”materialsareoftenchosenforinteriorsandformechanicalventilationsystemlinings.Thisconflictswiththe“ideal”indoorairqualitysolutionofhard,durable,non-poroussurfacematerialstoreduceemissionsand“sinkeffects”leadingtosecondaryemissions.SolutionstotheacousticproblemmustconsidertheIAQimplications,andtheIAQsolutionsmustconsidertheacousticimplicationsifdesignsaretoproducesatisfiedoccupants.Surfacesthathavenosoundabsorptioncapacitycanresultinveryuncomfortableandevendysfunctionalindoorspaces.Similarconsiderationsinvolvetheselectionanduseofcleaningproductsandprocedures,illumination,provisionofaccesstooperablewindowsandviews,amongmanyothers.Aneffectivedesignintegratestotalindoorenvironmentalqualityconcernsintoacompletedesignprogram.4.4InteractiveFactorsthatAffecttheAcceptabilityofIndoorEnvironmentalQualityExamplesofinteractionsamongenvironmentalfactorscanbeseenintheanalogouseffectsofmanycommonmedications,coffee,tobacco,alcohol,orso-calledrecreationaldrugs.Individualsensitivitiestoandtoleranceofthesemedicinesandotherphysiologicallyimportantagentsvariesgreatly.Itiscommonknowledgethatcertaincombinationsofprescribedmedicinesthatareconsideredsafewhentakenseparatelyshouldnotbetakentogetherbecauseoftheircombinedeffects.Itisnotcommonlyrecognizedthatindoorenvironmentalfactorscombinewitheachotherorwithotherfactorsaffectingthehumanresponsestothem.Fewofthepotentiallyinfinitecombinationsofinteractionsareadequatelyunderstoodorevenidentified.4.4.1EnvironmentalCarcinogens:ModifyingEffectofCo-CarcinogensonResponseAnon-toxicsubstancecangreatlyincreasethecarcinogeniceffectsofaknowncarcinogen(13.BinghamandFalk(14reportedthatcutaneoustumorigenesisinmiceisaccelerated1,000-foldbytheenhancementofpotencyatlowconcentrationsofbenzo[a]pyreneandbenz[a]anthracenewhenn-dodecaneisthediluent.Theyreportedthattheeffectwasmostobviousduringexposuretolowconcentrationsofthecarcinogen.Itisalsoknownthatexposuretoenvironmentaltobaccosmokeandasbestosatthesametimeisseveraltimesmorecarcinogenicthanseparateexposuretoeitheroftheseenvironmentalhazardsalone.Implications4.5PracticalThepracticalimplicationsarethatallpollutantsorotherenvironmentalstressesshouldbeminimizedinordertoreducethelikelihoodofanunacceptableindoorenvironment.Thisappliestoairpollutants(chemical,physical,andbiological,lightpollutants(glare,distortedcolorspectraldistribution,noise(loudand/orunpleasantsounds,andthermalconditionsthatarefarfromthecentralrangeofthermallyacceptableconditions.5INDOORAIRQUALITY(IAQTheacceptabilityofindoorairisdeterminedbythecriteriathatareappliedandtheperspectiveoftheperson(sororganizationdeterminingtheacceptabilityofthe.IAQ.Specifically,thecharacteristicsoftheairdetermineitsimpactontheoccupants,theenclosure,andthecontentsofthespace.Thus,thequalityofindooraircanbeinferredfromitsobservableeffectsonoccupantsandcontents.Indooraircanbecharacterizedbythemeasuredconcentrationsofchemicals,particles,andbiologicalagentsintheairandonsurfacesimmediatelysurroundingtheairinaspace.Itcanalsobecharacterizedbythewayitisperceivedbyoccupants,althoughtheseperceptionsmaynotrelatedirectly(orevenatalltothepotentialhealtheffectsresultingfromexposuretotheair.Theirritation,odor,andtoxicityofindoorairvarygreatly.Duetopotentialinteractionsamongtheconstituentsofairandthepotentialforinteractiveeffects(additive,synergistic,orprophylactic,itisnotpossibletodetermineallorevenmostoftheimpactsofindoorairdirectlyfromthemeasuredconcentrations.Itisevidentthattherearepotentiallyimportantchemicalcompoundsandbioaerosolsinindoorairthatarenotmeasuredormeasurable.Itiswidespreadpracticetomeasurecertaincharacteristicsofindoorairinordertoinferwhetheritishealthy.ASHRAEaddressesindoorairqualityinStandards62.1and62.2primarilybyestablishingrequirementsforventilationbelievedadequatetoprovidewhatitdefinesasacceptableindoorairqualityforthemajorityofadaptedoccupantsofaspaceorbyspecifyingthatasubstantialmajorityofoccupantsshouldfindtheindoorairquality“acceptable.”Thus,Standard62doesnotpurporttoprovideacceptableindoorairqualitytovisitorstoaspace.Thisisbecausevisitorsmaynotacceptanodorthathasbecomeeitherlessnoticeable,andthereforemoreacceptable,tooccupantswhohavebeeninaspaceforsomeperiodoftime.Standard62requirementsalsoincludecertaindesignfeaturesintendedtoavoidormitigatepotentialsourcesofindoorairpollutants.However,Standards62.1and62.2donotspecifythechemical,physical,orbiologicalcontentsoftheindoorairthatmeetitsdefinitionofacceptable.Instead,Standards62.1and62.2arebasedonlaboratorystudiesofsubjects’evaluationorratingoftheairqualityintermsofitsacceptabilitybasedonassumedsourcesandsourcestrengthsaswellasvariousventilationrates.Clearly,suchlaboratorystudiesdifferfromactualfieldexperienceinthatallfactorsinthestudiesexcepttheairqualityareheldconstant,eitherbyvaryingthepollutantsourcesorvaryingthedilutionrate.Inpractice,whileindoorairqualityvaries,otherfactorssuchasthermalconditions,acousticandvibrationconditions,andilluminationmayvaryaswell.Also,laboratorystudiesareusuallydonewithsubjectsthatarereasonablyhealthyandnotknowntobeparticularlysensitivetoindoorairpollutants.Furthermore,asotherconditionsvary,evenifventilationandsourcesremainthesame,contaminantconcentrationsmayvaryaswellasoccupantresponsestotheperceivedairqualityoritsimpactsonhumanphysiology.5.1VolatileOrganicCompounds(VOCsandOdor,IrritationResponsesCometto-Mu?izandCain(22havestudiedhumanodorperceptionandirritationresponsestoafewhomologousseriesofVOCs.Theyfoundthatincreasingthenumberofcompoundsinacomplexmixturelowersthethresholdsforodorandforeyeandnasalirritation.Infact,theyreportedthatincreasingcomplexityandlipophilicityofmixturesincreasedadditiveeffects.Eyeirritationshowedsynergisticeffectsforthemostlipophilicsubstancetestedinamixtureofsixcomponents.Theyconcludedthatmixturesofchemicalscausehumanresponsesevenwhentheindividualchemicalsareatconcentrationsfarbelowtheirindividualthresholds.5.1.1DesignCriteriaThepracticalimplicationsofthesefindingsarethatthedesignershoulddesigntheHVACtoprovidemoreoutsideairfordilutionthanmightnormallybeprovidedtoaparticulartypeofspace.Laboratorieswhereworkerscanbeexpectedtobeexposedtoavarietyofchemicalsarenormallyprovidedwithalloutsideairinordertomakeupchemicalfumehoodexhaust.5.1.2FormaldehydeandOtherIndoorAirPollutants:TheCaseforaSynergisticEffectConcentrationsofHCHOandVOCsnotknowntocauseirritationandotherSickBuildingSyndrome(SBScomplaintsalonecausesuchcomplaintswhenpresenttogether.Morethan80%ofthemostcommonindoorairpollutantsidentifiedinbuildingsandinmaterialemissionswereclassifiedbyM?lhaveasmucousmembraneirritants(17.Thisfindingcouldbeexplainedifsomecompoundsactsynergistically,anditappearssomewhatplausibleiftheyactinaroughlyadditivefashion.5.1.3DesignCriteriaThepracticalimplicationsofthesefindingsarethatthedesignershouldstrivetouselowemittingmaterialsinthebuildings.Wherematerialsarereplacedinexistingbuildings,thereplacementworkshouldbeperformedduringunoccupiedperiodsandwithmaximumoutdoorairventilation.DesignersshouldspecifythatoperatorsshouldruntheHVACsystemonalloutsideairinordertoflushoutpotentialcarcinogensfortwoweekspriortoneworrenovatebuildingsbeingoccupied.orfor100completeairchanges,whicheverisgreater.5.1.4VDTWorkandIndoorAirPollutionSchneideretal(19measuredparticledepositionvelocitiesonamannequinandmodeledfactorsdeterminingparticledepositionvelocities.Theyconcludedthatparticledepositionvelocitiesonoperatorfacialskinandeyesmaybeincreaseduptoten-foldbyelectrostaticfieldsandaircurrentsfromvisualdisplayterminals(VDT.Theweakertheaircurrents,theyfound,thegreatertheinfluenceoftheelectrostaticfields.Theelectricalfieldinfluencesaregreatest,accordingtothemodel,forparticlesnear1μm;aircurrentsaremostimportantforparticlesnear10μm.Theresultsareimportantforassessingthecontri