Background radiation - Wikipedia

Background radiation is a measure of the level of ionizing radiation present in the environment at a particular location which is not due to deliberate ... Backgroundradiation FromWikipedia,thefreeencyclopedia Jumptonavigation Jumptosearch Measureofionizingradiationintheenvironment Forbackgroundradiationfromspace,seecosmicbackgroundradiation. Backgroundradiationisameasureofthelevelofionizingradiationpresentintheenvironmentataparticularlocationwhichisnotduetodeliberateintroductionofradiationsources. Backgroundradiationoriginatesfromavarietyofsources,bothnaturalandartificial.Theseincludebothcosmicradiationandenvironmentalradioactivityfromnaturallyoccurringradioactivematerials(suchasradonandradium),aswellasman-mademedicalX-rays,falloutfromnuclearweaponstestingandnuclearaccidents. Contents 1Definition 2Backgrounddoserateexamples 3Naturalbackgroundradiation 3.1Terrestrialsources 3.2Airbornesources 3.3Cosmicradiation 3.4Foodandwater 3.5Areaswithhighnaturalbackgroundradiation 3.6Photoelectric 3.7Neutronbackground 4Artificialbackgroundradiation 4.1Atmosphericnucleartesting 4.2Occupationalexposure 4.3Nuclearaccidents 4.4Nuclearfuelcycle 4.5Energysources 4.5.1Coalburning 5Othersourcesofdoseuptake 5.1Medical 5.2Consumeritems 6Radiationmetrology 7Seealso 8References 9Externallinks Definition[edit] BackgroundradiationisdefinedbytheInternationalAtomicEnergyAgencyas"Doseordoserate(oranobservedmeasurerelatedtothedoseordoserate)attributabletoallsourcesotherthantheone(s)specified.[1]Soadistinctionismadebetweendosewhichisalreadyinalocation,whichisdefinedhereasbeing"background",andthedoseduetoadeliberatelyintroducedandspecifiedsource.Thisisimportantwhereradiationmeasurementsaretakenofaspecifiedradiationsource,wheretheexistingbackgroundmayaffectthismeasurement.Anexamplewouldbemeasurementofradioactivecontaminationinagammaradiationbackground,whichcouldincreasethetotalreadingabovethatexpectedfromthecontaminationalone. However,ifnoradiationsourceisspecifiedasbeingofconcern,thenthetotalradiationdosemeasurementatalocationisgenerallycalledthebackgroundradiation,andthisisusuallythecasewhereanambientdoserateismeasuredforenvironmentalpurposes. Backgrounddoserateexamples[edit] Backgroundradiationvarieswithlocationandtime,andthefollowingtablegivesexamples: Averageannualhumanexposuretoionizingradiationinmillisieverts(mSv)peryear Radiationsource World[2] US[3] Japan[4] Remark Inhalationofair 1.26 2.28 0.40 mainlyfromradon,dependsonindooraccumulation Ingestionoffood&water 0.29 0.28 0.40 (K-40,C-14,etc.) Terrestrialradiationfromground 0.48 0.21 0.40 dependsonsoilandbuildingmaterial Cosmicradiationfromspace 0.39 0.33 0.30 dependsonaltitude subtotal(natural) 2.40 3.10 1.50 sizeablepopulationgroupsreceive10–20 mSv Medical 0.60 3.00 2.30 worldwidefigureexcludesradiotherapy;USfigureismostlyCTscansandnuclearmedicine. Consumeritems – 0.13 cigarettes,airtravel,buildingmaterials,etc. Atmosphericnucleartesting 0.005 – 0.01 peakof0.11 mSvin1963anddecliningsince;highernearsites Occupationalexposure 0.005 0.005 0.01 worldwideaveragetoworkersonlyis0.7 mSv,mostlyduetoradoninmines;[2]USismostlyduetomedicalandaviationworkers.[3] Chernobylaccident 0.002 – 0.01 peakof0.04 mSvin1986anddecliningsince;highernearsite Nuclearfuelcycle 0.0002 0.001 upto0.02 mSvnearsites;excludesoccupationalexposure Other – 0.003 Industrial,security,medical,educational,andresearch subtotal(artificial) 0.61 3.14 2.33 Total 3.01 6.24 3.83 millisievertsperyear Naturalbackgroundradiation[edit] TheweatherstationoutsideoftheAtomicTestingMuseumonahotsummerday.Displayedbackgroundgammaradiationlevelis9.8 μR/h(0.82 mSv/a)Thisisveryclosetotheworldaveragebackgroundradiationof0.87 mSv/afromcosmicandterrestrialsources. Cloudchambersusedbyearlyresearchersfirstdetectedcosmicraysandotherbackgroundradiation.Theycanbeusedtovisualizethebackgroundradiation Radioactivematerialisfoundthroughoutnature.Detectableamountsoccurnaturallyinsoil,rocks,water,air,andvegetation,fromwhichitisinhaledandingestedintothebody.Inadditiontothisinternalexposure,humansalsoreceiveexternalexposurefromradioactivematerialsthatremainoutsidethebodyandfromcosmicradiationfromspace.Theworldwideaveragenaturaldosetohumansisabout2.4 mSv(240 mrem)peryear.[2]Thisisfourtimestheworldwideaverageartificialradiationexposure,whichin2008amountedtoabout0.6millisieverts(60 mrem)peryear.Insomedevelopedcountries,liketheUSandJapan,artificialexposureis,onaverage,greaterthanthenaturalexposure,duetogreateraccesstomedicalimaging.InEurope,averagenaturalbackgroundexposurebycountryrangesfromunder2 mSv(200 mrem)annuallyintheUnitedKingdomtomorethan7 mSv(700 mrem)annuallyforsomegroupsofpeopleinFinland.[5] TheInternationalAtomicEnergyAgencystates: "Exposuretoradiationfromnaturalsourcesisaninescapablefeatureofeverydaylifeinbothworkingandpublicenvironments.Thisexposureisinmostcasesoflittleornoconcerntosociety,butincertainsituationstheintroductionofhealthprotectionmeasuresneedstobeconsidered,forexamplewhenworkingwithuraniumandthoriumoresandotherNaturallyOccurringRadioactiveMaterial(NORM).ThesesituationshavebecomethefocusofgreaterattentionbytheAgencyinrecentyears."[6] Terrestrialsources[edit] Mainarticle:Environmentalradioactivity Terrestrialradiation,forthepurposeofthetableabove,onlyincludessourcesthatremainexternaltothebody.Themajorradionuclidesofconcernarepotassium,uraniumandthoriumandtheirdecayproducts,someofwhich,likeradiumandradonareintenselyradioactivebutoccurinlowconcentrations.Mostofthesesourceshavebeendecreasing,duetoradioactivedecaysincetheformationoftheEarth,becausethereisnosignificantamountcurrentlytransportedtotheEarth.Thus,thepresentactivityonearthfromuranium-238isonlyhalfasmuchasitoriginallywasbecauseofits4.5billionyearhalf-life,andpotassium-40(half-life1.25billionyears)isonlyatabout8%oforiginalactivity.Butduringthetimethathumanshaveexistedtheamountofradiationhasdecreasedverylittle. Manyshorterhalf-life(andthusmoreintenselyradioactive)isotopeshavenotdecayedoutoftheterrestrialenvironmentbecauseoftheiron-goingnaturalproduction.Examplesoftheseareradium-226(decayproductofthorium-230indecaychainofuranium-238)andradon-222(adecayproductofradium-226insaidchain). Thoriumanduranium(andtheirdaughters)primarilyundergoalphaandbetadecay,andaren'teasilydetectable.However,manyoftheirdaughterproductsarestronggammaemitters.Thorium-232isdetectableviaa239 keVpeakfromlead-212,511,583and2614 keVfromthallium-208,and911and969 keVfromactinium-228.Uranium-238manifestsas609,1120,and1764 keVpeaksofbismuth-214(cf.thesamepeakforatmosphericradon).Potassium-40isdetectabledirectlyviaits1461 keVgammapeak.[7] Thelevelovertheseaandotherlargebodiesofwatertendstobeaboutatenthoftheterrestrialbackground.Conversely,coastalareas(andareasbythesideoffreshwater)mayhaveanadditionalcontributionfromdispersedsediment.[7] Airbornesources[edit] Thebiggestsourceofnaturalbackgroundradiationisairborneradon,aradioactivegasthatemanatesfromtheground.Radonanditsisotopes,parentradionuclides,anddecayproductsallcontributetoanaverageinhaleddoseof1.26 mSv/a(millisievertperyear).Radonisunevenlydistributedandvarieswithweather,suchthatmuchhigherdosesapplytomanyareasoftheworld,whereitrepresentsasignificanthealthhazard.Concentrationsover500timestheworldaveragehavebeenfoundinsidebuildingsinScandinavia,theUnitedStates,Iran,andtheCzechRepublic.[8]Radonisadecayproductofuranium,whichisrelativelycommonintheEarth'scrust,butmoreconcentratedinore-bearingrocksscatteredaroundtheworld.Radonseepsoutoftheseoresintotheatmosphereorintogroundwaterorinfiltratesintobuildings.Itcanbeinhaledintothelungs,alongwithitsdecayproducts,wheretheywillresideforaperiodoftimeafterexposure. Althoughradonisnaturallyoccurring,exposurecanbeenhancedordiminishedbyhumanactivity,notablyhouseconstruction.Apoorlysealeddwellingfloor,orpoorbasementventilation,inanotherwisewellinsulatedhousecanresultintheaccumulationofradonwithinthedwelling,exposingitsresidentstohighconcentrations.ThewidespreadconstructionofwellinsulatedandsealedhomesinthenorthernindustrializedworldhasledtoradonbecomingtheprimarysourceofbackgroundradiationinsomelocalitiesinnorthernNorthAmericaandEurope.[citationneeded]Basementsealingandsuctionventilationreduceexposure.Somebuildingmaterials,forexamplelightweightconcretewithalumshale,phosphogypsumandItaliantuff,mayemanateradoniftheycontainradiumandareporoustogas.[8] Radiationexposurefromradonisindirect.Radonhasashorthalf-life(4days)anddecaysintoothersolidparticulateradium-seriesradioactivenuclides.Theseradioactiveparticlesareinhaledandremainlodgedinthelungs,causingcontinuedexposure.Radonisthusassumedtobethesecondleadingcauseoflungcanceraftersmoking,andaccountsfor15,000to22,000cancerdeathsperyearintheUSalone.[9][better source needed]However,thediscussionabouttheoppositeexperimentalresultsisstillgoingon.[10] About100,000 Bq/m3ofradonwasfoundinStanleyWatras'sbasementin1984.[11][12]HeandhisneighboursinBoyertown,Pennsylvania,UnitedStatesmayholdtherecordforthemostradioactivedwellingsintheworld.Internationalradiationprotectionorganizationsestimatethatacommitteddosemaybecalculatedbymultiplyingtheequilibriumequivalentconcentration(EEC)ofradonbyafactorof8to9nSv·m3/Bq·handtheEECofthoronbyafactorof40nSv·m3/Bq·h.[2] Mostoftheatmosphericbackgroundiscausedbyradonanditsdecayproducts.Thegammaspectrumshowsprominentpeaksat609,1120,and1764 keV,belongingtobismuth-214,aradondecayproduct.Theatmosphericbackgroundvariesgreatlywithwinddirectionandmeteorologicalconditions.Radonalsocanbereleasedfromthegroundinburstsandthenform"radonclouds"capableoftravelingtensofkilometers.[7] Cosmicradiation[edit] Mainarticle:Cosmicray Estimateofthemaximumdoseofradiationreceivedatanaltitudeof12km20January2005,followingaviolentsolarflare.Thedosesareexpressedinmicrosievertsperhour. TheEarthandalllivingthingsonitareconstantlybombardedbyradiationfromouterspace.ThisradiationprimarilyconsistsofpositivelychargedionsfromprotonstoironandlargernucleiderivedfromoutsidetheSolarSystem.Thisradiationinteractswithatomsintheatmospheretocreateanairshowerofsecondaryradiation,includingX-rays,muons,protons,alphaparticles,pions,electrons,andneutrons.Theimmediatedosefromcosmicradiationislargelyfrommuons,neutrons,andelectrons,andthisdosevariesindifferentpartsoftheworldbasedlargelyonthegeomagneticfieldandaltitude.Forexample,thecityofDenverintheUnitedStates(at1650meterselevation)receivesacosmicraydoseroughlytwicethatofalocationatsealevel.[13]Thisradiationismuchmoreintenseintheuppertroposphere,around10 kmaltitude,andisthusofparticularconcernforairlinecrewsandfrequentpassengers,whospendmanyhoursperyearinthisenvironment.Duringtheirflightsairlinecrewstypicallygetanadditionaloccupationaldosebetween2.2 mSv(220 mrem)peryear[14]and2.19mSv/year,[15]accordingtovariousstudies.[16] Similarly,cosmicrayscausehigherbackgroundexposureinastronautsthaninhumansonthesurfaceofEarth.Astronautsinloworbits,suchasintheInternationalSpaceStationortheSpaceShuttle,arepartiallyshieldedbythemagneticfieldoftheEarth,butalsosufferfromtheVanAllenradiationbeltwhichaccumulatescosmicraysandresultsfromtheEarth'smagneticfield.OutsidelowEarthorbit,asexperiencedbytheApolloastronautswhotraveledtotheMoon,thisbackgroundradiationismuchmoreintense,andrepresentsaconsiderableobstacletopotentialfuturelongtermhumanexplorationofthemoonorMars. Cosmicraysalsocauseelementaltransmutationintheatmosphere,inwhichsecondaryradiationgeneratedbythecosmicrayscombineswithatomicnucleiintheatmospheretogeneratedifferentnuclides.Manyso-calledcosmogenicnuclidescanbeproduced,butprobablythemostnotableiscarbon-14,whichisproducedbyinteractionswithnitrogenatoms.ThesecosmogenicnuclideseventuallyreachtheEarth'ssurfaceandcanbeincorporatedintolivingorganisms.Theproductionofthesenuclidesvariesslightlywithshort-termvariationsinsolarcosmicrayflux,butisconsideredpracticallyconstantoverlongscalesofthousandstomillionsofyears.Theconstantproduction,incorporationintoorganismsandrelativelyshorthalf-lifeofcarbon-14aretheprinciplesusedinradiocarbondatingofancientbiologicalmaterials,suchaswoodenartifactsorhumanremains. Thecosmicradiationatsealevelusuallymanifestsas511 keVgammaraysfromannihilationofpositronscreatedbynuclearreactionsofhighenergyparticlesandgammarays.Athigheraltitudesthereisalsothecontributionofcontinuousbremsstrahlungspectrum.[7] Foodandwater[edit] Twooftheessentialelementsthatmakeupthehumanbody,namelypotassiumandcarbon,haveradioactiveisotopesthataddsignificantlytoourbackgroundradiationdose.Anaveragehumancontainsabout17milligramsofpotassium-40(40K)andabout24nanograms(10−9 g)ofcarbon-14(14C),[citationneeded](half-life5,730years).Excludinginternalcontaminationbyexternalradioactivematerial,thesetwoarethelargestcomponentsofinternalradiationexposurefrombiologicallyfunctionalcomponentsofthehumanbody.About4,000nucleiof40K[17]decaypersecond,andasimilarnumberof14C.Theenergyofbetaparticlesproducedby40Kisabout10timesthatfromthebetaparticlesfrom14Cdecay. 14Cispresentinthehumanbodyatalevelofabout3700Bq(0.1 μCi)withabiologicalhalf-lifeof40days.[18]Thismeansthereareabout3700betaparticlespersecondproducedbythedecayof14C.However,a14Catomisinthegeneticinformationofabouthalfthecells,whilepotassiumisnotacomponentofDNA.Thedecayofa14CatominsideDNAinonepersonhappensabout50timespersecond,changingacarbonatomtooneofnitrogen.[19] Theglobalaverageinternaldosefromradionuclidesotherthanradonanditsdecayproductsis0.29 mSv/a,ofwhich0.17 mSv/acomesfrom40K,0.12 mSv/acomesfromtheuraniumandthoriumseries,and12 μSv/acomesfrom14C.[2] Areaswithhighnaturalbackgroundradiation[edit] Someareashavegreaterdosagethanthecountry-wideaverages.[20]Intheworldingeneral,exceptionallyhighnaturalbackgroundlocalesincludeRamsarinIran,GuarapariinBrazil,KarunagappalliinIndia,[21]ArkaroolainAustralia[22]andYangjianginChina.[23] ThehighestlevelofpurelynaturalradiationeverrecordedontheEarth'ssurfacewas90 µGy/honaBrazilianblackbeach(areiapretainPortuguese)composedofmonazite.[24]Thisratewouldconvertto0.8Gy/aforyear-roundcontinuousexposure,butinfactthelevelsvaryseasonallyandaremuchlowerinthenearestresidences.TherecordmeasurementhasnotbeenduplicatedandisomittedfromUNSCEAR'slatestreports.NearbytouristbeachesinGuarapariandCumuruxatibawerelaterevaluatedat14and15 µGy/h.[25][26]NotethatthevaluesquotedhereareinGrays.ToconverttoSieverts(Sv)aradiationweightingfactorisrequired;theseweightingfactorsvaryfrom1(beta&gamma)to20(alphaparticles). ThehighestbackgroundradiationinaninhabitedareaisfoundinRamsar,primarilyduetotheuseoflocalnaturallyradioactivelimestoneasabuildingmaterial.The1000mostexposedresidentsreceiveanaverageexternaleffectiveradiationdoseof6 mSv(600 mrem)peryear,sixtimestheICRPrecommendedlimitforexposuretothepublicfromartificialsources.[27]Theyadditionallyreceiveasubstantialinternaldosefromradon.Recordradiationlevelswerefoundinahousewheretheeffectivedoseduetoambientradiationfieldswas131 mSv(13.1 rem)peryear,andtheinternalcommitteddosefromradonwas72 mSv(7.2 rem)peryear.[27]Thisuniquecaseisover80timeshigherthantheworldaveragenaturalhumanexposuretoradiation. EpidemiologicalstudiesareunderwaytoidentifyhealtheffectsassociatedwiththehighradiationlevelsinRamsar.Itismuchtooearlytodrawunambiguousstatisticallysignificantconclusions.[27]Whilesofarsupportforbeneficialeffectsofchronicradiation(likelongerlifespan)hasbeenobservedinfewplacesonly,[27]aprotectiveandadaptiveeffectissuggestedbyatleastonestudywhoseauthorsnonethelesscautionthatdatafromRamsararenotyetsufficientlystrongtorelaxexistingregulatorydoselimits.[28]However,therecentstatisticalanalysesdiscussedthatthereisnocorrelationbetweentheriskofnegativehealtheffectsandelevatedlevelofnaturalbackgroundradiation.[29] Photoelectric[edit] Backgroundradiationdosesintheimmediatevicinityofparticlesofhighatomicnumbermaterials,withinthehumanbody,haveasmallenhancementduetothephotoelectriceffect.[30] Neutronbackground[edit] Mostofthenaturalneutronbackgroundisaproductofcosmicraysinteractingwiththeatmosphere.Theneutronenergypeaksataround1 MeVandrapidlydropsabove.Atsealevel,theproductionofneutronsisabout20neutronspersecondperkilogramofmaterialinteractingwiththecosmicrays(or,about100–300neutronspersquaremeterpersecond).Thefluxisdependentongeomagneticlatitude,withamaximumnearthemagneticpoles.Atsolarminimums,duetolowersolarmagneticfieldshielding,thefluxisabouttwiceashighvsthesolarmaximum.Italsodramaticallyincreasesduringsolarflares.Inthevicinityoflargerheavierobjects,e.g.buildingsorships,theneutronfluxmeasureshigher;thisisknownas"cosmicrayinducedneutronsignature",or"shipeffect"asitwasfirstdetectedwithshipsatsea.[7] Artificialbackgroundradiation[edit] Displaysshowingambientradiationfieldsof0.120–0.130 μSv/h(1.05–1.14 mSv/a)inanuclearpowerplant.Thisreadingincludesnaturalbackgroundfromcosmicandterrestrialsources. Atmosphericnucleartesting[edit] PercapitathyroiddosesinthecontinentalUnitedStatesresultingfromallexposureroutesfromallatmosphericnucleartestsconductedattheNevadaTestSitefrom1951to1962. Atmospheric14C,NewZealand[31]andAustria.[32]TheNewZealandcurveisrepresentativefortheSouthernHemisphere,theAustriancurveisrepresentativefortheNorthernHemisphere.Atmosphericnuclearweapontestsalmostdoubledtheconcentrationof14CintheNorthernHemisphere.[33]Frequentabove-groundnuclearexplosionsbetweenthe1940sand1960sscatteredasubstantialamountofradioactivecontamination.Someofthiscontaminationislocal,renderingtheimmediatesurroundingshighlyradioactive,whilesomeofitiscarriedlongerdistancesasnuclearfallout;someofthismaterialisdispersedworldwide.Theincreaseinbackgroundradiationduetothesetestspeakedin1963atabout0.15 mSvperyearworldwide,orabout7%ofaveragebackgrounddosefromallsources.TheLimitedTestBanTreatyof1963prohibitedabove-groundtests,thusbytheyear2000theworldwidedosefromthesetestshasdecreasedtoonly0.005 mSvperyear.[34] Occupationalexposure[edit] TheInternationalCommissiononRadiologicalProtectionrecommendslimitingoccupationalradiationexposureto50 mSv(5rem)peryear,and100 mSv(10rem)in5years.[35] However,backgroundradiationforoccupationaldosesincludesradiationthatisnotmeasuredbyradiationdoseinstrumentsinpotentialoccupationalexposureconditions.Thisincludesbothoffsite"naturalbackgroundradiation"andanymedicalradiationdoses.Thisvalueisnottypicallymeasuredorknownfromsurveys,suchthatvariationsinthetotaldosetoindividualworkersisnotknown.Thiscanbeasignificantconfoundingfactorinassessingradiationexposureeffectsinapopulationofworkerswhomayhavesignificantlydifferentnaturalbackgroundandmedicalradiationdoses.Thisismostsignificantwhentheoccupationaldosesareverylow. AtanIAEAconferencein2002,itwasrecommendedthatoccupationaldosesbelow1–2mSvperyeardonotwarrantregulatoryscrutiny.[36] Nuclearaccidents[edit] Radiationlevelinarangeofsituations,fromnormalactivitiesuptothenuclearaccidents.Eachstepupthescaleindicatesatenfoldincreaseinradiationlevel. Undernormalcircumstances,nuclearreactorsreleasesmallamountsofradioactivegases,whichcausesmallradiationexposurestothepublic.EventsclassifiedontheInternationalNuclearEventScaleasincidentstypicallydonotreleaseanyadditionalradioactivesubstancesintotheenvironment.Largereleasesofradioactivityfromnuclearreactorsareextremelyrare.Tothepresentday,thereweretwomajorcivilianaccidents–theChernobylaccidentandtheFukushimaInuclearaccidents–whichcausedsubstantialcontamination.TheChernobylaccidentwastheonlyonetocauseimmediatedeaths. TotaldosesfromtheChernobylaccidentrangedfrom10to50mSvover20yearsfortheinhabitantsoftheaffectedareas,withmostofthedosereceivedinthefirstyearsafterthedisaster,andover100mSvforliquidators.Therewere28deathsfromacuteradiationsyndrome.[37] TotaldosesfromtheFukushimaIaccidentswerebetween1and15mSvfortheinhabitantsoftheaffectedareas.Thyroiddosesforchildrenwerebelow50mSv.167cleanupworkersreceiveddosesabove100mSv,with6ofthemreceivingmorethan250mSv(theJapaneseexposurelimitforemergencyresponseworkers).[38] TheaveragedosefromtheThreeMileIslandaccidentwas0.01mSv.[39] Non-civilian:Inadditiontothecivilianaccidentsdescribedabove,severalaccidentsatearlynuclearweaponsfacilities–suchastheWindscalefire,thecontaminationoftheTechaRiverbythenuclearwastefromtheMayakcompound,andtheKyshtymdisasteratthesamecompound–releasedsubstantialradioactivityintotheenvironment.TheWindscalefireresultedinthyroiddosesof5–20mSvforadultsand10–60mSvforchildren.[40]ThedosesfromtheaccidentsatMayakareunknown. Nuclearfuelcycle[edit] TheNuclearRegulatoryCommission,theUnitedStatesEnvironmentalProtectionAgency,andotherU.S.andinternationalagencies,requirethatlicenseeslimitradiationexposuretoindividualmembersofthepublicto1 mSv(100mrem)peryear. Energysources[edit] PerUNECElife-cycleassessment,nearlyallsourcesofenergyresultinsomelevelofoccupationalandpublicexposuretoradionuclidesasresultoftheirmanufacturingoroperations.Thefollowingtableusesman·Sievert/GW-annum:[41] Source Public Occupational Nuclearpower 0.43 4.5 Coal(modern) 0.7 11 Coal(older) 1.4 11 Naturalgas 0.1 0.02 Oil 0.0003 0.15 Geothermal 1–20 0.05 Solarpower 0.8 Windpower 0.1 Biomass 0.01 Coalburning[edit] Coalplantsemitradiationintheformofradioactiveflyashwhichisinhaledandingestedbyneighbours,andincorporatedintocrops.A1978paperfromOakRidgeNationalLaboratoryestimatedthatcoal-firedpowerplantsofthattimemaycontributeawhole-bodycommitteddoseof19 µSv/atotheirimmediateneighboursinaradiusof500m.[42]TheUnitedNationsScientificCommitteeontheEffectsofAtomicRadiation's1988reportestimatedthecommitteddose1 kmawaytobe20 µSv/aforolderplantsor1 µSv/afornewerplantswithimprovedflyashcapture,butwasunabletoconfirmthesenumbersbytest.[43]Whencoalisburned,uranium,thoriumandalltheuraniumdaughtersaccumulatedbydisintegration –radium,radon,polonium –arereleased.[44]Radioactivematerialspreviouslyburiedundergroundincoaldepositsarereleasedasflyashor,ifflyashiscaptured,maybeincorporatedintoconcretemanufacturedwithflyash. Othersourcesofdoseuptake[edit] Medical[edit] Theglobalaveragehumanexposuretoartificialradiationis0.6 mSv/a,primarilyfrommedicalimaging.Thismedicalcomponentcanrangemuchhigher,withanaverageof3 mSvperyearacrosstheUSApopulation.[3]Otherhumancontributorsincludesmoking,airtravel,radioactivebuildingmaterials,historicalnuclearweaponstesting,nuclearpoweraccidentsandnuclearindustryoperation. Atypicalchestx-raydelivers20 µSv(2mrem)ofeffectivedose.[45]Adentalx-raydeliversadoseof5to10µSv.[46]ACTscandeliversaneffectivedosetothewholebodyrangingfrom1to20mSv(100to2000mrem).TheaverageAmericanreceivesabout3 mSvofdiagnosticmedicaldoseperyear;countrieswiththelowestlevelsofhealthcarereceivealmostnone.Radiationtreatmentforvariousdiseasesalsoaccountsforsomedose,bothinindividualsandinthosearoundthem. Consumeritems[edit] Cigarettescontainpolonium-210,originatingfromthedecayproductsofradon,whichsticktotobaccoleaves.Heavysmokingresultsinaradiationdoseof160mSv/yeartolocalizedspotsatthebifurcationsofsegmentalbronchiinthelungsfromthedecayofpolonium-210.Thisdoseisnotreadilycomparabletotheradiationprotectionlimits,sincethelatterdealwithwholebodydoses,whilethedosefromsmokingisdeliveredtoaverysmallportionofthebody.[47] Radiationmetrology[edit] Inaradiationmetrologylaboratory,backgroundradiationreferstothemeasuredvaluefromanyincidentalsourcesthataffectaninstrumentwhenaspecificradiationsourcesampleisbeingmeasured.Thisbackgroundcontribution,whichisestablishedasastablevaluebymultiplemeasurements,usuallybeforeandaftersamplemeasurement,issubtractedfromtheratemeasuredwhenthesampleisbeingmeasured. ThisisinaccordancewiththeInternationalAtomicEnergyAgencydefinitionofbackgroundasbeing"Doseordoserate(oranobservedmeasurerelatedtothedoseordoserate)attributabletoallsourcesotherthantheone(s)specified.[1] Thesameissueoccurswithradiationprotectioninstruments,whereareadingfromaninstrumentmaybeaffectedbythebackgroundradiation.Anexampleofthisisascintillationdetectorusedforsurfacecontaminationmonitoring.Inanelevatedgammabackgroundthescintillatormaterialwillbeaffectedbythebackgroundgamma,whichwilladdtothereadingobtainedfromanycontaminationwhichisbeingmonitored.Inextremecasesitwillmaketheinstrumentunusableasthebackgroundswampsthelowerlevelofradiationfromthecontamination.Insuchinstrumentsthebackgroundcanbecontinuallymonitoredinthe"Ready"state,andsubtractedfromanyreadingobtainedwhenbeingusedin"Measuring"mode. RegularRadiationmeasurementiscarriedoutatmultiplelevels.Governmentagenciescompileradiationreadingsaspartofenvironmentalmonitoringmandates,oftenmakingthereadingsavailabletothepublicandsometimesinnear-real-time.Collaborativegroupsandprivateindividualsmayalsomakereal-timereadingsavailabletothepublic.InstrumentsusedforradiationmeasurementincludetheGeiger–MüllertubeandtheScintillationdetector.Theformerisusuallymorecompactandaffordableandreactstoseveralradiationtypes,whilethelatterismorecomplexandcandetectspecificradiationenergiesandtypes.Readingsindicateradiationlevelsfromallsourcesincludingbackground,andreal-timereadingsareingeneralunvalidated,butcorrelationbetweenindependentdetectorsincreasesconfidenceinmeasuredlevels. Listofnear-real-timegovernmentradiationmeasurementsites,employingmultipleinstrumenttypes: EuropeandCanada:EuropeanRadiologicalDataExchangePlatform(EURDEP)SimplemapofGammaDoseRates USA:EPARadnetnear-real-timeandlaboratorydatabystate Listofinternationalnear-real-timecollaborative/privatemeasurementsites,employingprimarilyGeiger-Mullerdetectors: GMCmap:http://www.gmcmap.com/(mixofold-datadetectorstationsandsomenear-real-timeones) Netc:http://www.netc.com/ Radmon:http://www.radmon.org/ RadiationNetwork:http://radiationnetwork.com/ Radioactive@Home:http://radioactiveathome.org/map/ Safecast:http://safecast.org/tilemap(thegreencirclesarereal-timedetectors) uRadMonitor:http://www.uradmonitor.com/ Seealso[edit] Backgroundradiationequivalenttime(BRET) Bananaequivalentdose Environmentalradioactivity Flight-timeequivalentdose Noise(electronics) Low-backgroundsteel References[edit] 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Externallinks[edit] BackgroundradiationdescriptionfromtheRadiationEffectsResearchFoundation EnvironmentalandBackgroundRadiationFAQfromtheHealthPhysicsSociety RadiationDoseChartfromtheAmericanNuclearSociety RadiationDoseCalculatorfromtheUnitedStatesEnvironmentalProtectionAgency vteRadiationprotectionMainarticles Backgroundradiation Dosimetry Healthphysics Ionizingradiation Internaldosimetry Radioactivecontamination Radioactivesources Radiobiology Measurementquantitiesandunits Absorbeddose Becquerel Committeddose Computedtomographydoseindex Countsperminute Effectivedose Equivalentdose Gray Meanglandulardose Monitorunit Rad Roentgen Rem Sievert Instrumentsandmeasurementtechniques Airborneradioactiveparticulatemonitoring Dosimeter Geigercounter Ionchamber Scintillationcounter Proportionalcounter Radiationmonitoring Semiconductordetector Surveymeter Whole-bodycounting Protectiontechniques Leadshielding Glovebox Potassiumiodide Radonmitigation Respirators Organisations Euratom HPS(USA) IAEA ICRU ICRP IRPA SRP(UK) UNSCEAR Regulation IRR(UK) NRC(USA) ONR(UK) RadiationProtectionConvention,1960 Radiationeffects Acuteradiationsyndrome Radiation-inducedcancer SeealsothecategoriesMedicalphysics,Radiationeffects,Radioactivity,Radiobiology,andRadiationprotection vteRadiation(physicsandhealth)MainarticlesNon-ionizingradiation Acousticradiationforce Infrared Light Starlight Sunlight Microwave Radiowaves Ultraviolet Ionizingradiation Radioactivedecay Clusterdecay Backgroundradiation Alphaparticle Betaparticle Gammaray Cosmicray Neutronradiation Nuclearfission Nuclearfusion Nuclearreactors Nuclearweapons Particleaccelerators Radioactivematerials X-ray Earth'senergybudget Electromagneticradiation Synchrotronradiation Thermalradiation Black-bodyradiation Particleradiation Gravitationalradiation Cosmicbackgroundradiation Cherenkovradiation Askaryanradiation Bremsstrahlung Unruhradiation Darkradiation Radiationandhealth Radiationsyndrome acute chronic Healthphysics Dosimetry Electromagneticradiationandhealth Lasersafety Lasersandaviationsafety Medicalradiography Radiationprotection Radiationtherapy Radiationdamage Radioactivityinthelifesciences Radioactivecontamination Radiobiology Biologicaldoseunitsandquantities Wirelessdeviceradiationandhealth Wirelesselectronicdevicesandhealth Radiationheat-transfer Linearenergytransfer Radiationincidents Listofcivilianradiationaccidents 1996CostaRicaaccident 1987Goiâniaaccident 1984Moroccanaccident 1990Zaragozaaccident Relatedarticles Half-life Nuclearphysics Radioactivesource Radiationhardening Havanasyndrome SeealsothecategoriesRadiationeffects,Radioactivity,Radiobiology,andRadiationprotection Portals: Nucleartechnology Astronomy Stars Spaceflight Outerspace SolarSystem Authoritycontrol:Nationallibraries Germany Japan Retrievedfrom"https://en.wikipedia.org/w/index.php?title=Background_radiation&oldid=1095098844" Categories:BackgroundradiationCosmicraysIonizingradiationRadioactivityHiddencategories:WebarchivetemplatewaybacklinksAllarticleswithfailedverificationArticleswithfailedverificationfromApril2011AllarticleswithbareURLsforcitationsArticleswithbareURLsforcitationsfromMarch2022ArticleswithPDFformatbareURLsforcitationsAllarticleswithdeadexternallinksArticleswithdeadexternallinksfromOctober2018ArticleswithpermanentlydeadexternallinksArticleswithshortdescriptionShortdescriptionisdifferentfromWikidataUsedmydatesfromApril2019AllarticleswithunsourcedstatementsArticleswithunsourcedstatementsfromDecember2012AllarticleslackingreliablereferencesArticleslackingreliablereferencesfromDecember2012ArticleswithunsourcedstatementsfromNovember2013ArticleswithGNDidentifiersArticleswithNDLidentifiers Navigationmenu Personaltools NotloggedinTalkContributionsCreateaccountLogin Namespaces ArticleTalk English Views ReadEditViewhistory More Search Navigation MainpageContentsCurrenteventsRandomarticleAboutWikipediaContactusDonate Contribute HelpLearntoeditCommunityportalRecentchangesUploadfile Tools WhatlinkshereRelatedchangesUploadfileSpecialpagesPermanentlinkPageinformationCitethispageWikidataitem Print/export DownloadasPDFPrintableversion Languages AfrikaansالعربيةDanskEsperantoفارسیFrançaisGaeilge한국어ՀայերենHrvatskiBahasaIndonesiaItalianoМакедонскиNederlands日本語NorskbokmålPolskiРусскийSimpleEnglishСрпски/srpskiSuomiSvenskaதமிழ்TürkçeTiếngViệt中文 Editlinks