Radiation Sources and Doses | US EPA

Background radiation Skiptomaincontent Officialwebsitesuse.gov A.govwebsitebelongstoanofficialgovernmentorganizationintheUnitedStates. Secure.govwebsitesuseHTTPS Alock(LockAlockedpadlock)orhttps://meansyou’vesafelyconnectedtothe.govwebsite.Sharesensitiveinformationonlyonofficial,securewebsites. RadiationProtection ContactUs RadiationSourcesandDoses SourcesofradiationradiationEnergygivenoffaseitherparticlesorrays.areallaroundusallthetime.Somearenaturalandsomeareman-made. Theamountofradiationabsorbedbyapersonismeasuredindose.Adoseistheamountofradiationenergyabsorbedbythebody.SeeRadiationBasics forinformationabout dose. Onthispage: Backgroundradiation AverageU.S.dosesandsources Dosesfromcommonradiationsources PeriodicTable Clicktheimagebelow toenlargetheperiodictableandseewhichexistonlyasradioactiveisotopesandaresourcesofradiation. BackgroundRadiation BackgroundradiationBackgroundradiationRadiationthatisalwaysintheenvironment.Themajorityofbackgroundradiationoccursnaturallyandasmallfractioncomesfromman-madeelements.ispresentonEarthatalltimes. Themajorityofbackgroundradiationoccursnaturallyfrommineralsandasmallfractioncomesfrom man-madeelements.Naturallyoccurringradioactivemineralsintheground,soil,andwaterproducebackgroundradiation.Thehumanbodyevencontainssomeofthesenaturally-occurringradioactiveminerals.Cosmicradiationfromspacealsocontributesto thebackgroundradiationaroundus.Therecanbelargevariancesinnaturalbackgroundradiationlevelsfromplacetoplace,aswellaschangesinthesamelocationovertime. CosmicRadiation CosmicradiationcomesfromextremelyenergeticparticlesfromthesunandstarsthatenterEarth’satmosphere.Someparticlesmakeittotheground,whileothersinteractwiththeatmospheretocreatedifferenttypesofradiation.Radiationlevelsincreaseasyougetclosertothesource,sotheamountofcosmicradiationgenerallyincreaseswithelevation.Thehigherthealtitude,thehigherthedose.ThatiswhythoselivinginDenver,Colorado (altitudeof5,280feet)receiveahigherannualradiationdosefromcosmicradiation thansomeonelivingatsealevel(altitudeof0feet). LearnmoreaboutcosmicradiationinRadTown,EPA'sradiationeducationwebareaforstudentsandteachers.  DoseCalculator Estimateyouryearlydosefromthemostcommonsourcesofionizingradiationwiththisinteractiveonlinedosecalculator. RadioactiveMaterialsintheEarthandinOurBodies Uranium and thorium naturallyfoundintheeartharecalledprimordialprimordialExistingsincetheformationofthesolarsystem,naturallyoccurring.radionuclidesradionuclideRadioactiveformsofelementsarecalledradionuclides.Radium-226,Cesium-137,andStrontium-90areexamplesofradionuclides.andarethesourceof terrestrialradiation.Traceamountsof uranium, thorium andtheirdecayproducts canbe foundeverywhere. Learnmoreaboutradioactivedecay. Terrestrialradiationlevelsvarybylocation,butareaswithhigherconcentrationsofuraniumandthoriuminsurfacesoilsgenerallyhavehigherdoselevels.  Tracesofradioactivematerialscanbefoundinthebody,mainlynaturallyoccurringpotassium-40.Potassium-40 isfoundinthefood,soil,andwaterweingest. Ourbodiescontainsmallamountsofradiationbecausethebodymetabolizesthenon-radioactiveandradioactiveformsofpotassiumandotherelementsinthesameway. Man-madeSources A smallfractionofbackgroundradiationcomesfromhumanactivities.Traceamountsofradioactiveelementshavedispersedintheenvironmentfromnuclearweaponstestsand accidentslike theone attheChernobylnuclearpowerplantinUkraine. Nuclearreactorsemitsmallamountsofradioactiveelements.Radioactive materialsusedin industryandeveninsomeconsumerproductsarealsoasourceofsmallamountsofbackgroundradiation. Learnmoreaboutradiationandconsumerproducts.  AverageU.S.DosesandSources Allofusareexposedtoradiationeveryday,from naturalsourcessuchasmineralsintheground,and man-madesourcessuchasmedicalx-rays.AccordingtotheNationalCouncilonRadiationProtectionandMeasurements(NCRP),theaverageannualradiationdoseperpersonintheU.S.is 6.2millisieverts(620millirem)millirem).Thepiechartbelowshowsthesourcesofthisaveragedose. Source: NationalCouncilon RadiationProtection&Measurements(NCRP),ReportNo.160 MostofouraverageannualdosecomesfromnaturalbackgroundradiationbackgroundradiationRadiationthatisalwaysintheenvironment.Themajorityofbackgroundradiationoccursnaturallyandasmallfractioncomesfromman-madeelements.sources: Theradioactivegasesradonandthoron,whicharecreatedwhenothernaturallyoccurringelementsundergoradioactivedecay. Space(cosmicradiation). Naturallyoccurringradioactiveminerals: Internal(inyourbody). Terrestrial(intheground). Another48percentoftheaverageAmerican’sdosecomesfrommedicalprocedures.Thistotaldoesnotincludethedosefromradiationtherapyusedinthetreatmentofcancer,whichistypicallymanytimeslarger. UsetheRadiationDoseCalculatortoestimateyouryearly dose fromsourcesof ionizingradiation. DosesfromCommonRadiationSources Thefollowingdiagramcomparesradiationdosesfromcommonradiationsources,bothnaturalandman-made. Sources: NationalCouncilon RadiationProtection&Measurements(NCRP),ReportNo.160  InternationalCommissiononRadiological Protection,Publication103  ContactUstoaskaquestion,providefeedback,orreportaproblem. LastupdatedonNovember5,2021