Radon: The Gas, Threat, Detection, And Control

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Title:
Radon: The Gas, Threat, Detection, And Control
Physical Description:
Fact sheet
Creator:
Cook, Gary D.
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.

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Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
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Published
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"EES-45"

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University of Florida Institutional Repository
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University of Florida
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All rights reserved by the submitter.
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IR00004809:00001


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Florida Energy Extension Service TheInstituteofFoodandAgriculturalSciencesisanEqualOpportunity/AffirmativeActionEmployerauthorizedtoprovideresearch,educational informationandotherservicesonlytoindividualsandinstitutionsthatfunctionwithoutregardtorace,color,sex,ornationalorigin. FloridaCooperativeExtensionService/InstituteofFoodandAgriculturalSciences/UniversityofFlorida/JohnT.Woeste,DeanRadon:TheGas,Threat,Detection,andControl1GaryD.Cook2THEGASRadonisapotentiallydangerousradioactivegas occurringnaturallyintheenvironment.Itisoneofa longchainofdecayproductsofuranium,which ultimatelyturnstoradiumandthentononradioactivelead.Radonhasahalf-lifeof3.8days. Thismeansthatforeverygivenquantityofradon, halfofitwillchangeintoanisotopein3.8days. Beinganoblegas,radondoesnotchemicallyreact withotherelementstoformcompounds. Relativelyhighradonconcentrationsare producedbysoilshavingsignificantquantitiesof uraniumandradium.InFlorida,eighteencounties withdefiniteevidenceofelevatedradonpotential havebeenidentified(Figure1).Countiesparticularly susceptibletohighradonpotentialareHillsborough, Polk,Marion,Alachua,andcountiestothenorther andnorthwestofAlachua. Evenwithincountiesofhighradonpotential, thereisawidevarianceinpredictinglevelswithin houses.Soilshavingsignificantquantitiesofuranium andradiumproducerelativelyhighradon concentrations,butthereareothergeologicalfactors thatmayconfineordirectthegasintocertainareas. Clay,forexample,isrelativeimpermeabletoradon gas,butiftheclayhasbeenerodedbystreamsor othernaturalforces,radonmayhaveanopportunity toleakintohomeslocatedintheseparticularareas. Ahomewithinsignificantradonlevelscanbelocated rightinthemidstofotherhomeshavinghighradon levels.THETHREATTherehasbeendocumentationofalongstanding correlationbetweensmokingandlungcancer.Inthe past,researchershavebeenpuzzledbythenumberof non-smokerswhodevelopedlungcancer.Ittooka numberofyears,butaconnectionwasestablished betweenlungcancerinnon-smokersandexposureto highradonlevels. Radonproducesradiationwhenitdecaysintoits progeny,alsocalled"daughters"ofradon.Indoing so,alpha,betaandgammaradiationisproduced. Radonlevelsaremeasuredinpicocuriesperliter, picocuriebeingaquantityofradiation,andaliter beingavolumeofair.Expertsvarywidelyinwhat theyconsiderarelativelysavelevel.The EnvironmentalProtectionAgency(EPA)has conservativelyestablishedradonlevelsof4picocuries perliter(pCi/l)orlowerasreasonablytolerable.The averageoutdoorlevelofradonisabout0.2pCi/l;the averageindoorlevelofradonisaboutonepCi/l.A personlivinginahomewithanaverageradon concentrationof30pCi/lhasaboutthesameriskof developinglungcancerasapersonwhosmokestwo packsofcigarettesaday.Thisriskismaintainedas longasthepersonisexposedtothatlevel(referto RadonRiskEvaluationChart,Figure2).Theriskto apersondecreasesiftheindoorleveldecreases,orif thepersonspendsagreateramountoftimeaway fromthehouse. 1.ThisdocumentwaspublishedasFactSheetEES-45,FloridaEnergyExtensionService.Formoreinformation,contactyourcountyCooperative ExtensionServiceoffice. 2.EnergyExtensionSpecialistforBuildingConstruction,FloridaEnergyExtensionService,InstituteofFoodandAgriculturalSciences,University ofFlorida,Gainesville. TheFloridaEnergyExtensionServicereceivesfundingfromtheGovernor'sEnergyOffice.Theinformationcontainedhereinistheproductof theFloridaEnergyExtensionServiceanddoesnotnecessarilyreflecttheviewsoftheGovernor'sEnergyOffice.

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Page2 Eveningeographicregionsknowntohavehigh radonlevels,theriskisminimaloutdoors.The problemcomeswiththegasaccumulatesinsidea home.Radonusuallyentersahomethroughcracks inthefoundation,intheslab,throughtheflooror throughtheconcreteblockincontactwiththe ground.Twoconditionsmustexistforradontobea probleminahome:(1)theremustbesignificant quantitiesofradongasemittedbythesoilthatthe homesitson,and(2)theconstruction,design,and physicsofthehomemustpermitradontogetinto andaccumulateinthehome. Situationsmayoccurwhereahome,locatedon radon-bearingsoil,maynothavesignificantradon concentrationsbecausecertainconstruction techniquesrestrictradonentry.Onesuchtechnique mayemploytheuseofacontinuousslabpouredover aplasticmembrane.Thismembrane,inturn,must notbepuncturedbyrocks,roots,construction workers,orpipes.Anothertechniqueusesoffgrade constructionwithawellventilatedcrawlspacebeneath thelivingarea.Homesshouldbetestedperiodically forradonbecausesettlingandsmallearthshiftsmay eventuallycausecracksinthefoundationandslab, allowingradonentryroutes.Evenaverysmallcrack canpermitarelativelylargeamountofradontoenter ahome.

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Page4DETECTIONOne'snormalsensescannotdeterminethe presenceofradonbecausethegascannotbesmelled, seen,felt,ortasted.Therearetwomethodsused commonlytodetectradon:charcoalcanistersand alphatrackdetectors.Bothofthesecommercially availabledetectorsareexposedtoairinahomefora specifiedperiodoftime,andalaboratorydetermines thelevelofradon. Withthemorecommoncharcoalcanister,thetest periodisgenerallyfromtwotosevendays.Atestkit cannormallybepurchasedinvariousretailoutlets suchaspharmacies,hardware,health,orgrocery storesforbetween$5and$25.Afterbeingexposed tothehome'satmosphere,thetestkitmustbe promptlysenttoalaboratoryforanalysis.An additionallaboratoryfeeof$10to$20maybe requiredatthistime. Anothermethodisthealphatrackdetectorwhich hasaminimumtestperiodoftwotofourweeks.The approximatecostisbetween$20and$50forone detector,includinglaboratoryanalysis.Thealpha trackdetectorisnotascommonasthecharcoal canister,butitusuallyproducesabetteraverage readingbecauseofthelongertestperiod.Boththe alphatrackandthecharcoalcanistercomewith completeinstructionswhichshouldbefollowed. Forafamilyconcernedabouttheriskofradonin theirhome,itissuggestedthattheyfirstpurchasea charcoaltestcanister.Becausehigherlevelsare expectedwhenthehouseisclosed,thebesttimeto testisinthewinterorinthesummerwhenthe windowsareclosedforheatingorcooling.The canistersaregenerallylocatedaboutthreefeetoffthe floorinanareasuspectedtohavecracksorpipes runningthroughthefoundation,thuspermitting radontogetintothehome.Otherlocationshaving highpotentialforgasintrusionincludebasements,or areasofthehomepartiallyunderground.Mosttests suggestthatthehomebeclosedasmuchaspossible; windowsclosedanddooropeningsminimizedduring theentireperiodofthetest.Afterthetestperiodis completed,thecanistershouldimmediatelybesentto thelaboratory. Ifthereadingissignificantlyabove4pCi/l,then theoccupantsmaywishtoconductafollow-uptest usinganalphatrackdetector.Thistestprovidesa betteraveragereadingundernormallivingconditions. Othertechniquesforradondetectionexist,butthey requireoperationbytrainedpersonnelandaremuch moreexpensivethaneitherthecharcoalcanisteror alphatrackdetection.CONTROLIfthedetectorshowsthatyouhavelevelsof radonhigherthan4pCi/l,therearestepsan individualcantakeimmediatelytoreducetheriskof developinglungcancer: 1.Themostimportantisnottosmokeandnot topermitsmokinginyourhome.Thiswill reducethefamily'soverallriskofdeveloping lungcancer.Whenradondecays,highly radioactiveparticles(radon'sprogeny)tendto attachtosmokeanddustparticleswherethey maybeeasilybreathedintothelungs. 2.Spendlesstimeinareashavinghigher concentrationsofradon. 3.Wheneverpractical,openwindowsoruse fanstoincreaseairflowintothehome. 4.Donotopenwindowsorusefansinsucha waythattheycreateanegativepressure withinthehouse.Itisimportantthatair blowintoahome,ratherthanbesuckedout ofthehome.Ifahomehasacrawlspace, makesurethatalltheventsareopenand vegetationandweedsareclearedawayfrom themsothatamaximumamountof ventilationispermittedthroughthevents. Thesesuggestionswillreduceriskbuttheydonot offeralong-termsolution.Toreduceradonlevelson apermanentbasis,physicalmodificationsmustbe made.Someareveryexpensiveandmayincrease utilitybills.Twosimplelowenergymodificationsa homeownercanmakearesuggestedhere:1) ventilatingthecrawlspaceisgenerallyalowenergy radonmitigationtechniqueforhomesbuiltoffgrade; 2)sealingradonentrypoints,suchasknowncracksin thefoundationorslab,orsealingaroundpipesthat gothroughtheslaborfoundationintotheground, particularlybathtubsandtoiletfixtures.Afterdoing thiswithahighgradeofsealant,thehomeshouldbe retested.Iftheradonlevelisstillsignificantlyabove

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Page5 4pCi/lafterretesting,thecountyenvironmental officerorcountyhealthdepartmentshouldbe contacted.Theymightbeabletoreferyouto professionalsqualifiedtomitigate(reduce)theradon levels.Buyerbeware--askquestions.Contracts shouldbeinwriting,guaranteeingresults. Somemoreexpensivemitigationtechniques requiredrillingthroughthehome'sceilingandroof. Therearealsoothersub-slabventilationtechniques. (SeeTable1). Forfurtherinformation,pleasecontacttheOffice ofRadiationControl,P.O.Box15590,Orlando,FL 32858((407)297-2095),oryourcountypublichealth unit.

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Page6 ComparisonofMitigationTechniques Method Installation Cost Operating Cost Maximum Possible Reductions* Comment Naturalventilation: Usefulimmediatestepto reducehighradonlevels Basementorlowest floor Minimal Veryhigh Upto90% Crawlspace Minimal Moderate Upto90% Forcedventilation Morecontrolledthannatural ventilation Basementorlowest floor Low Veryhigh Upto90% Crawlspace Low Moderate Upto90% Airsupply Lowto moderate Low Sitespecific Mayberequiredtomake othermethodswork Heatrecovery ventilation Moderate tohigh Moderate Upto90+% Airintakeandexhaustmust beequal Coveringexposed earth Moderate Low Sitespecific Requiredtomakemostother methodswork Sealingcracksand spaces Minimalto moderate None Sitespecific Requiredtomakemostother methodswork Drain-tilesuction Moderate tohigh Low Upto97+% Bestwhendraintilesare continuous,unblockedloop Block-wall ventilation Highto veryhigh Low Upto97+% Appliestoblock-wall basements.Sub-slabsuction maybeneededtosupplement Sub-slabsuction Highto veryhigh Low Upto97+% Importanttohavegood aggregateorhighly permeablesoilunderslab *Theserepresentthebestreductionsthatasinglemethodcanaccomplish.Youmaygethigheror lowerreductionsdependingontheuniquecharacteristicsofyourhouse.Itislikelythatreductions inyourhousewillnotbeasgreatasthoseshown.Especiallywithhighinitialradonlevels,several methodsmayhavetobecombinedtoachieveacceptableresults. Source:U.S.EnvironmentalProtectionAgency.RadonReductionMethods:AHomeowner's Guide,Washington,D.C.,ResearchandDevelopment,August1986.

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Page7REFERENCES1.Nagda,N.L.,M.D.Koontz,R.C.Fortman,W.A. ShoenbornandL.L.Mehegan, "FloridaStatewide RadiationStudy," PublicationNo.05-029-057, Bartow,FL:FloridaInstituteofPhosphate Research,December1987. 2.U.S.EnvironmentalProtectionAgency. A Citizen'sGuidetoRadon:whatitisandwhatto doaboutit. Washington,D.c.,OfficeofAirand Radiation,U.S.DepartmentofHealthand HumanServices,CentersforDiseaseControl, August1986. 3.U.S.EnvironmentalProtectionAgency. Interim IndoorRadonandRadonDecayProduct MeasurementProtocols. Washington,D.C.,Office ofRadiationPrograms,February1986. 4.U.S.EnvironmentalProtectionAgency. Radon/RadonProgenyMeasurementProficiency Program:CumulativeProficiencyReport. ResearchTrianglePark,NorthCarolina,Radon TechnicalInformationService,July1987. 5.U.S.EnvironmentalProtectionAgency. Radon ReductionMethods:AHomeowner'sGuide. Washington,D.C.,ResearchandDevelopment, August1986. 6.U.S.EnvironmentalProtectionAgency. Radon ReductionTechniquesforDetachedHouses: TechnicalGuidance. ResearchTrianglePark, NorthCarolina,AirandEnergyEngineering ResearchLaboratory,OfficeofEnvironmental EngineeringandTechnology,OfficeofResearch andDevelopment,June1986. 7.U.S.EnvironmentalProtectionAgency. Reducing RadoninStructures:TrainingforRadonDiagnosis andMitigation (StudentManual).Washington, D.C.,OfficeofRadiationPrograms,EPA contract68-01-7030.ADDITIONALREFERENCE1.Roessler,GenevieveS., "IndoorRadonProgeny ExposureintheFloridaPhosphateMiningRegion: AReview." HealthPhysics,45,1983,p.389.