Chapter45-IndoorEnvironmentalControlCONTROLOFINDOORENVIRONMENTS:GENERALPRINCIPLESA.HernándezCallejaPeopleinurbansettingsspendbetween80and90%oftheirtimeinindoorspaceswhilecarryingoutsedentaryactivities,bothduringworkandduringleisuretime.(Seefigure45.1).Figure45.1Urbandwellersspend80to90%oftheirtimeindoorsThisfactledtothecreationwithintheseindoorspacesofenvironmentsthatweremorecomfortableandhomogeneousthanthosefoundoutdoorswiththeirchangingclimaticconditions.Tomakethispossible,theairwithinthesespaceshadtobeconditioned,beingwarmedduringthecoldseasonandcooledduringthehotseason.Forairconditioningtobeefficientandcost-effectiveitwasnecessarytocontroltheaircomingintothebuildingsfromtheoutside,whichcouldnotbeexpectedtohavethedesiredthermalcharacteristics.Theresultwasincreasinglyairtightbuildingsandmorestringentcontroloftheamountofambientairthatwasusedtorenewstagnantindoorair.Theenergycrisisatthebeginningofthe1970s—andtheresultingneedtosaveenergy—representedanotherstateofaffairsoftenresponsiblefordrasticreductionsinthevolumeofambientairusedforrenewalandventilation.Whatwascommonlydonethenwastorecycletheairinsideabuildingmanytimesover.Thiswasdone,ofcourse,withtheaimofreducingthecostofair-conditioning.Butsomethingelsebegantohappen:thenumberofcomplaints,discomfortand/orhealthproblemsoftheoccupantsofthesebuildingsincreasedconsiderably.This,inturn,increasedthesocialandfinancialcostsduetoabsenteeismandledspecialiststostudytheoriginofcomplaintsthat,untilthen,werethoughttobeindependentofpollution.Itisnotacomplicatedmattertoexplainwhatledtotheappearanceofcomplaints:buildingsarebuiltmoreandmorehermetically,thevolumeofairsuppliedforventilationisreduced,morematerialsandproductsareusedtoinsulatebuildingsthermally,thenumberofchemicalproductsandsyntheticmaterialsusedmultipliesanddiversifiesandindividualcontroloftheenvironmentisgraduallylost.Theresultisanindoorenvironmentthatisincreasinglycontaminated.Theoccupantsofbuildingswithdegradedenvironmentsthenreact,forthemostpart,byexpressingcomplaintsaboutaspectsoftheirenvironmentandbypresentingclinicalsymptoms.Thesymptomsmostcommonlyheardofarethefollowingsort:irritationofmucousmembranes(eyes,noseandthroat),headaches,shortnessofbreath,higherincidenceofcolds,allergiesandsoon.Whenthetimecomestodefinethepossiblecausesthattriggerthesecomplaints,theapparentsimplicityofthetaskgiveswayinfacttoaverycomplexsituationasoneattemptstoestablishtherelationofcauseandeffect.Inthiscaseonemustlookatallthefactors(whetherenvironmentalorofotherorigins)thatmaybeimplicatedinthecomplaintsorthehealthproblemsthathaveappeared.Theconclusion—aftermanyyearsofstudyingthisproblem—isthattheseproblemshavemultipleorigins.Theexceptionsarethosecaseswheretherelationshipofcauseandeffecthasbeenclearlyestablished,asinthecaseoftheoutbreakofLegionnaires’disease,forexample,ortheproblemsofirritationorofincreasedsensitivityduetoexposuretoformaldehyde.Thephenomenonisgiventhenameofsickbuildingsyndrome,andisdefinedasthosesymptomsaffectingtheoccupantsofabuildingwherecomplaintsduetomalaisearemorefrequentthanmightbereasonablyexpected.Table45.1showssomeexamplesofpollutantsandthemostcommonsourcesofemissionsthatcanbeassociatedwithadropinthequalityofindoorair.Table45.1ThemostcommonindoorpollutantsandtheirsourcesSiteSourcesofemissionPollutantOutdoorsFixedsourcesIndustrialsites,energyproductionSulphurdiox...
