Optical Safety LED Lighting

OpticalsafetyofLEDlighting

1stEdition,July2011

1. BackgroundWiththephasingoutofincandescentlampsintheEuropeanUnionaswellassimultaneouslyinmanyothercountries,theintroductionofmanynewLEDbasedlightsources(lamps,modules)andluminaires,raisesthequestion as towhether the spectral characteristicsof the LED and Energy Saving fluorescent lamps (CFLintegrated)aregoodenoughtoreplacetraditionalincandescentlamps.Theseconcernsaregenerallyraisedbygroupsofpeoplewithahighsensitivityforcertainradiationontheirskinoreyes,especiallyforradiationintheUVandbluepartofthespectrum.Thisdocumentwillfocusonwhite lightsourcesandtheiruse inhouseholds.2. SummarystatementItisoftenemphasizedthatLEDbasedlightsourcesaredifferentfromtraditionallampsinthattheycontainhigherproportionsofbluewavelength lightandarethusmore likelytocauseproblemssuchasblue lighthazard. Confronted with this question, the European Lighting Industry represented by ELC & CELMA,presentsadetailedevaluationofthephotobiologicalsafetyofcommonLEDlightsourcesfordomesticuseincomparisontotraditionallamps.Thefocusisonwhitelightsourcesusedinhouseholds.Tosummarize thekey findings,LEDsources (lampsorsystems)and luminairesaresafe totheconsumerwhenusedas intended. Intermsoftheir levelofphotobiologicalsafety,LED lampsarenodifferentfromtraditionaltechnologiessuchasincandescentlampsandfluorescenttubes.TheportionofblueinLEDisnotdifferent from theportionofblue in lampsusingother technologies at the same colour temperature.AcomparisonofLEDretrofitproductstothetraditionalproductstheyareintendedtoreplacerevealsthattherisklevelsareverysimilarandwellwithintheuncriticalrange.Nevertheless, looking straight into bright, pointlike sources (LEDs, but also other strong pointlike lightsources,likeclearfilamentordischargelampsandincludingthesun)shouldbeprevented.However,whenpeople happen to look into a bright light source accidentally, a natural protective reflex occurs (peopleinstinctivelyclosetheireyesorlookawayfromthesource).Itneedstobementionedthatblue lightexposure is importanttohumanbeings.Blue lightwithapeakataround460480nmregulatesthebiologicalclock,alertnessandmetabolicprocesses.Innaturalconditions,outdoordaylightfulfilsthisfunction.Yet,peoplespendmostofthedayindoors(officesetc.)andareoftenlackingthenecessaryblue lightexposure.Blueandcoolwhite lightsourcescanbeusedtocreate lightingconditionssuchthatpeoplewillreceivetheirdailyportionofbluelighttokeeptheirphysiologyintunewiththenaturaldaynightrhythm.Duetothehighlyflexibleapplicationpossibilities,LEDbasedlightsourcesareparticularlywellsuitedforthatpurpose.

CELMAELCLEDWG(SM)011_ELCCELMApositionpaperopticalsafetyLEDlighting_Final_July2011 2of18

3. LEDandopticalsafetyOpticalsafety refers to theprevention1ofhazards throughoptical radiation (electromagnetic radiationofwavelengthsrangingfrom100nmto1mm).Effectsontheeyesaswellastheskinareconsidered,alsoforthosepeoplewithahighersensitivity.Inresponsetotheconcernsraisedbythelastgroup,Annex1providesmoredetailedconsiderationsforthisspecificgroup.Commonly discussed hazards affecting the eye are blue light hazard (BLH) and agerelated maculardegeneration(AMD)whichcanbeinducedoraggravatedbyhighintensitybluelight.Whenlookingdirectlyintoabrightlightsource,aphotochemicaldamagetotheretina(bluelighthazard)canoccur,dependingontheintensityinvolvedandthetimeofexposure.Peoplearefamiliarwiththisphenomenonfromlookingatthesun.Topreventretinaldamages,appropriatespectaclesmustbewornwhenobservingasolareclipse,forinstance.Onabrightandsunnyday,however,anaturalreflexoccurs(eyelidclosereflex,aversion)thatprotectstheeyefrombeingharmed.Furthermore,UV(ultraviolet)mayaffecttheeye,causingcataractorphotokeratitis (sunburn of the cornea); IR (infrared) radiation can induce IR cataract (also known asglassblowerscataract);andradiationofallwavelengthsatextreme intensitiescan leadtoretinalthermalinjuries.Optical radiationcanalsoaffect theskincausing forexamplesunburns,or, inseverecases,cancersuponlongterm UV exposure. There exist certain groups of patients, e.g. suffering from lupus orphotodermatoses,whoareparticularlysensitivetoUV(andsometimesalsobluelight)radiation.Notethattheabovementionedeffectsarepredominantly causedbynatural sun light; someof themcanneverbeevokedbyartificiallighting.Nevertheless,theopticalsafetyofartificiallightsourcesneedstobeguaranteedand lightsensitivepatients areprovidedwith appropriate lamps that are a good and safe alternative toincandescentlamps.4. PhotobiologicalriskassessmentandconclusionsThephotochemicalblue lighthazard canbeevaluatedon thebasisof the standardEN62471.The latterclassifieslightsourcesintoriskgroups0,1,2and3(from0=noriskthroughto3=highrisk).Thesunwouldbe classified as being in the highest risk group. CELMA and ELC member companies ensure that theirproductscomplywiththephotobiologicalsafetystandard.Riskscanbeallocatedtotheriskgroupsaccordingtodifferentmeasurementcriteria:Onemethodmeasures the distance atwhich an illuminance of 500 Lux is attained (a typical value forgeneral lightingpurposes).AccordingtoEN62471,the500Luxcriterionmustbeusedfor lamps intendedfor general lighting (including lamps for lighting offices, schools, homes, factories, roadways, orautomobiles).Asecondcriterionmeasuresphotobiologicalsafetyfromadistanceof200millimetres.The200millimetrecriterion is tobeused forallother lamps (including forexample lamps forsuchprofessionalusesas filmprojection, reprographic processes, sun tanning, industrial processes,medical treatment and searchlightapplications).It is fundamentallypurposeful tomake thisdistinctiononedoesnot look intoaceiling luminaire in theoffice fromadistanceof200millimetres,butpossibly incertain industrialapplicationsworkersmightberequired to look into lightsources fromashort200mmdistance,e.g.duringqualitycontrolprocesses. Insuchcasesspecialinstructionsareneededtopreventeyedamage.When light sourcesareplaced ina luminaire, theRG classification can changeby theopticsused in theluminaire:

1. IncasealuminaireintegratealightsourceclassifiedRG0orRG1,nonewtestsarenecessary

1ExposurelimitsdefinedinthestandardEN62471areinEuropeanregulation(directive2006/25/CE)


2. Incasea luminaire isnot intendingtochangean integrated lightsourcewithclassificationRG2orRG#3,nonewtestsarenecessaryandproductinformationshallindicatethementionedRGclass.

3. IncasealuminaireischangingtheoriginalcharacteristicsoftheusedlightsourceRG2orRG3inanyform,anewmeasurementisneededtoclassifytheluminaire.

4.1ConclusionsonbluelightemissionEvaluationatadistanceproducing500Lux:Takingthe500Luxcriterionasthemeasurementbasis,noneoftheLEDproductsbelongstoriskgroup2.ThiswasalsoconfirmedbyastudyoftheFrenchagencyforfood,environmentalandoccupationalhealth&safety(ANSES)in2010whichfoundthatevenhighoutputdiscreteLEDsareclassifiedintoriskgroups0or1ifthe500Luxcriterionisapplied.LEDcomparedtootherlightsourcesWith regard to photo biological safety, LED is not fundamentally different to lamps using traditionaltechnologies,suchasincandescentorfluorescentlamps.TheportionofbluelightinLEDisnothigherthantheportionofbluelightinlampsusingothertechnologiesatthesamecolourtemperature(seefigure2 inannex 3with the blue hazard irradiance values EB of awide range of productswith comparable ColourTemperature).IfLEDretrofitproductsareobservedincomparisontotheproductswhichtheyareintendedto replace (e.g. LEDMR16 vs.HalogenMR16,ora LED retrofitwith screwbase vs. frosted incandescentlamp),itappearsthattheriskgroupratingsaresimilar.

Figure1:relativespectralpowerofvariouslightsources


PrecautionarymeasureswithregardtochildrenThelensofachildseyefiltersbluelightlessefficientlythananadultslens.Childrenarethusmoresensitivetobluelighthazard.Therefore,atplacesfrequentedbychildrenparticularcaremustbetakentoensurethatlampsandluminairesarechosenandinstalledinsuchawayastoavoidpeoplelookingdirectlyintothelightsource.ItisnotnecessarythatLEDs(orbluelightingeneral)areavoidedinanenvironmentwithchildrenpresent,forthereasonsstatedabove.Ifusedacrossabroadsurfaceorarea,inawaywhichdoesnotproduceglare,even"pure"bluelightiscompletelyharmless;regardlessofwhetheritistheblueindaylightorproducedbyLEDsorotherlightsources.GuidanceforpeoplewithhighsensitivityforbluelightTheabovestatementsarevalidforhealthypeopleinthegeneralpublic.Peoplewithhighlysensitiveskinoreyes for blue lightmay bewise to investigate alternative light sources that operate on amore specificradiation band not covered by the applied action curves that cover a broad range of radiations. Thecomparativedatagiven intheannexesofthispaperservetogiveguidance inselectingthebestavailabletypeoflightsourceforagivensensitivity.ThebiologicalimportanceofbluelightItneeds tobementioned thatblue lightexposure is important tohumanbeings.Blue lightwith apeakaround 460480nm regulates the biological clock, alertness and metabolic processes. CELMAELC hasinstalledaspecialworkinggrouptotranslatethesefindingsintopracticalapplicationnormsandstandards.In natural conditions, outdoor daylight fulfils this function. Yet, people spend most of the day indoors(officesetc.)andareoftenlackingthenecessarybluelightexposure.Blueandcoolwhitelightsourcescanbeusedtocreate lightingconditionssuchthatpeoplewillreceivetheirdailyportionofblue lighttokeeptheir physiology in tune with the natural daynight rhythm. Due to the highly flexible applicationpossibilities,LEDbasedlightsourcesareparticularlywellsuitedforthatpurpose.

4.2Conclusionsonultravioletradiation(UV)LED based light sources do not emit any UV radiation (unless specifically designed for that particularpurpose).Therefore,theyarenotharmfultopeoplewithaspecificsensitivityforcertainUVradiationandcanbring relief tocertaingroupsofpatients. In this respect,LEDbased light sourcesprovideadvantagesovertraditionalincandescent,halogenandCompactFluorescentlamps.FormoredetailsseeAnnex2.4.3Conclusionsoninfraredradiation(IR)In contrast tomost other light sources, e.g. halogen and incandescent lamps, LEDs hardly emit IR light(unlessspecificallydesignedtoemitacertaintypeof IR).Foravailabletypesof indoor lightsourcesthe IRradiationisnotpowerfulenoughtoposeanyriskstohuman.


Annex1:EffectsofopticalradiationoneyesandskinPotentialeffectsontheeyeCommonly discussed hazards affecting the eye are blue light hazard (BLH) and agerelated maculardegeneration (AMD)which can be induced or aggravated by high intensity blue light. Furthermore,UV(ultraviolet)may affect the eye, causing cataract or photokeratitis (sunburn of the cornea); IR (infrared)radiationcaninduceIRcataract(alsoknownasglassblowerscataract);and,radiationofallwavelengthscanleadtoretinalthermalinjuriesatextremeintensities.Togivealittlemorebackgrounddetails: Bluelighthazard(BLH)isdefinedasthepotentialforretinalinjuryduetohighenergyshortwavelength

light.Atveryhighintensities,bluelight(shortwavelength400500nm)canphotochemicallydestroythephotopigments (and some other molecules) which then act as free radicals and cause irreversible,oxidativedamagestoretinalcells(uptoblindness).Forsuchan injuriouseffecttooccur,threefactorsarecritical:first,thespectralirradiancedistribution(relevantistheproportionthatfallsintotheactionspectrum forblue lighthazard, inmathematical terms: the integrated spectral irradiancedistributionweightedwiththeactionspectrum);second,theradiance(athigherradiance,morephotonsare likelytohitphotopigments and causedamages); and, third, thedurationofexposure (at longerexposure,effects increasesteadily).Forexample,whengazingdirectlyatthesun,theretinacanbe injuredveryrapidlydue to theenormous radiance. Incontrast,even though for thesky the relativeproportionofblue light inrelationtothesky ismuchhigher,there isnoriskofretinaldamagesbythescatteredskylightastheradianceistoolow.

Agerelatedmaculardegeneration (AMD) isaconditionofvisual impairmentofthecentralvisualfield(macula) predominantly in elderly people. Blue light can progress AMD. According to the currentscientific literature, lipofuscin,amoleculemoreandmoreaccumulating intheretinalcellswithage, isdestroyedbybluelightcausingoxidativedamages.NotethattheprevalenceofAMDisnothigherwithhigherexposuretobluelightinyoungeryears,e.g.,inprofessionalsworkingpredominantlyoutsidesuchassailorsorfarmers.Asforblue lighthazard,thespectral irradiancedistributionandradiancearetherelevant factors influencingAMD.Butdifferent than inblue lighthazard,AMDcannotbecausedbyaonetimeacuteabovethresholdexposure to lightbut is instead influencedby longtermexposure toblue(andalsogreen&yellow),possiblyevenatlowerdoses.Butnotethatbluelightisnotthemainriskfactor,instead,intherecentmedicalliterature,geneticfactors(ERCC6gene)andenvironmentalfactorsincludingage,smoking,hypertensionanddietarediscussedtocause/influenceAMD.

Cataractisadisorderthatdevelopsoverlifetime.Whenpeopleareborn,thecrystallinelensesarefullytransparent for light. Due to natural aging and the absorption of UV radiation, the lenses turnopaque/yellowobstructing thepassageof light.Thesevere formof thisage relatedproblem iscalledcataract.Asasideeffect,whenturningyellowthelensservesasabluelightfilter,and,thus,asakindofnaturalprotectionfortheretinawhenpeoplegrowolder.Inseverecases,surgicalremoval(aphakia)orreplacement (pseudophakia)of the lensmaybecomenecessary.Suchpatientsaswellaschildrenareoftenmoresensitivetobluelightthanhealthyadultsare.

PotentialeffectsontheskinOpticalradiation,particularlyUVcanbeharmfultotheskin.Byfarthemosthazardoussourcetoconsideristhe sun.Sunburns (UVerythema)and skincancersdue to longtermexposure to the sunarewellknownproblems caused by radiation. Moreover, patients with autoimmune diseases such as lupus orphotodermatosescanbehighlysensitivetoUVradiation,andsometimesalsoblue light.There isconcernamongsomepatientswhosufferfromsuchsensitivitiesthatphasingoutoftheknownincandescentlampswillleavethemwithoutlampsforindoorusethatarelowinradiationofUVandbluelight.


Annex2:GeneralspectralcomparisonoflightsourcesusedinhouseholdsInthissection,spectraldataofdifferenttypesoflightsources(LED,CFLi,halogen)aregraphicallypresentedandevaluatedqualitatively (aquantitativeevaluationwill follow inAnnex3). Focusof interest ison thespectralirradianceintheblueandultravioletpartofthedifferenttypesoflightsourcesincomparisontothetwogoldenstandardsoflightingformostconsumers:daylightandincandescentlamps.Irradiancespectralmeasurementsweredonetoobtainthespectraofanumberofcommonlightsources,allatasimilaroverallilluminancelevelof500luxandinaccordancewiththeinternationalstandardEN62471.Forreference:500 lux isalsothe light levelused inawiderangeof indoorworkplace lightingapplicationssuchasofficelighting;inhomelightingvariesbetween50lux(TVcorner)to500lux(dinnertable,kitchen).Outdoor lightingconditionsareamultipleof indoor lighting:5000 lux (overcastsky) to50.000 lux (sunnyday).Note1:Themeasuredsourcesarepresentedagainsta logarithmicscaleas the linearscalewouldnotbeshowingwellthedifferencesbetweenthevariouscurves.Note2:Theareaunderthespectralcurvesofthelightsourcesisameasureoftheenergyinaparticularpartofthespectrum(egblueemission).Wheninterestedinaparticularrisk,asbluelighthazardoremissionofactinicUV,theareaneedstobespectrallyweightedbytheactioncurveforbluelighthazardoractinicUV,respectively(formoredetailsontheBLHandactinicUVactioncurvesseeAnnex4).LEDspectralcharacteristicsInFigure1 top,different LED sourcesare compared toan incandescent lampanddaylight.White LEDstypicallyshowapeak intheblue (ataround450nmwhenaroyalblueLED isused)andmorebroadbandemissioninthegreen/yellowpartofthespectrum.Nexttothebluepeak,adipisvisibleataround490nmthatalsofallsundertheBLHactioncurve(indicatedherebythebluehorizontalbar).ThebluepeakoftheLEDlampsiscompensatedbythedip,thereforethetotalblueoutput(givenbytheareaunderthecurve!)ofLEDof2700Kiscomparabletoanincandescentlampof2700K.Energysavers(compactfluorescentintegrated)spectralcharacteristicsIn Figure 1 middle, spectra of two common types of energy savers (or CFLi, Compact FluorescentIntegrated)areshownandcomparedtoan incandescent lampanddaylight.Typicalenergysaversspectracontainmultiplesharppeaksanddips.Again,whenconsideringtheareaunderthecurvetodeterminetheblueirradiance,peaksanddipsleveleachotherout.Notethatthehighpeaksareverynarrowandthereforedonotcontributethatmuchtotheblueirradiance(asitmightintuitivelyseemfromthegraphs).Onthelefthandside,thespectralcurvesextendslightlyintotheactinicUVactionspectrum.Butnotethatconsideringthat thedataareplottedagainsta logarithmicaxis, theenergy in theactinicUVpart isvery low (!)andclearlybelowtheemissionsofnaturaldaylight.


Figure2:Acollectionofspectrafromdifferentcommonlightsourcesisshown,togetherwitharepresentativedaylightspectrumscaledtothesameilluminancelevel.TheUVActinicandBLHactioncurves(asdefinedine.g.EN62471,seeannex4.3)areindicatedbythebrownandbluebars,respectively,thecolorintensityillustratestheeffectiveness

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HalogenspectralcharacteristicsIn Figure 1 bottom, various halogen lamp types are compared to an incandescent lamp and daylight.Halogenlampspectralcurvesshowasimilarshapeasincandescentlamps:thecurvescontinuouslyincreasetowardshigherwavelengthsandbenddownwardagainintheIR.Halogenlampscanthereforeofferagoodalternativetotheincandescentlamps.Thegreen linerepresentsahalogen lampwithan infraredcoating (IRCcurveclearlybendsdownwards intheIR).ThepurplelineshowsthattheUVfilteringquartzindeedeffectivelyfilterstheUV,bringingitclosetothe incandescentcurve.TheothertypesshowmoreUVoutputthan incandescent lamps,especiallythe500Wdoubleended lamp,butthat lampshouldbealwaysusedwithasuitablecoverglass (flood light)orsleeve(inuplighter);withthecoverglassthelampisclosetotheIncandescentcurve.Notethat,comparedwithdaylight,theUVoutputofall lamps israther low,asthescale is logarithmicnotlinear.SummaryEventhoughthespectraofLED,CFLi,halogenand incandescent lampshavedifferenttypicalshapes,theproportionofblue lightdoesnotvarymuchbetween lampsofdifferenttechnologieswithasimilarcolourtemperature)andisalwayssignificantlylowerthantheblue(orUV)emissionofdaylight.Foralllampsintendedforgenerallightingapplications,theUVemissioniswellbelowtheexposurelimitsasdefinedinEN62471.LEDsusedforgenerallightingarefreeofUV(asideveryspecialtypesthataredesignedtoemitUV).

Legendforthevariouslamptypesshowninfigure1(seealsoAnnex5foramoredetaileddescription): Halo:halogen lamps,canbe lowvoltage(12V,3000K)ormainsvoltage(230V,2800K).Halogen lamps

canbeacapsule (caps)orreflector (MR16)operated inaspecialhalogen lampholderor theycanbeintegrated into theoutlineof the known incandescent lamps as a replacement for those lamps (E27MV).

FluoES:EnergySaver(popularname)orCompactFluorescentIntegrated(CFLI,technicalname),canbejustthefluorescenttube(burner)orhaveasecondshell(bulb)

Incand:Incandescentlamp,consideredbythemarketasthegoldenstandard. LED:replacementalternativesaretaken:forincandescentbulbs,andHalogenreflectorlamps(MR16)or

T8fluorescenttubes Daylight:theofficialCIEdaylightcurveof6500Kistaken


Annex3:BluelightradiationdataoflightsourcesWhenevaluating the riskofblue lighthazardposedbyLED (andother) light sources, two fundamentallydifferentcasesneedtobeconsidered:CaseA:LookingatanilluminatedsceneInthevastamountofcases,humanslookatanilluminatedscene:Typicallydaylightilluminatesthesceneryand adirect view into the light source, the sun, is avoided.Or, in indoor lighting, artificial light sourcesilluminatetheroomwhileluminairespreventadirectviewofthelightsourceprimarilytoavoidglare.Inthecaseof lookingatan illuminatedscene,the(geometrical)propertiesofthe lightsourcesuchasthesizeoftheareafromwhichtheradiationisemitted(measureofthedensityofradiation~=radiance)arenotrelevant. Instead, the irradiance which refers to the radiation hitting a surface (scene) is the relevantproperty.CaseAcangenerallybeconsideredsafe.Togiveanexample, lookingat thescatteredbluesky (highblueirradiancebut lowradiance) iscompletelysafe,andsoareartificial lightsources,containingway lessblueirradiancethandaylight.CaseB:LookingatalightsourceWhenevaluatingphotobiologicalrisks(basedonEN62471)themoreseverecaseof lookingdirectly intoalightsourceisconsidered.Ineverydaysituations,thisrarelyhappens.ButnotethatthestandardEN62471wasoriginallydeveloped toprotectworkersparticularly in the lighting industry,as lighting installersor insimilar fields. Itmayhappen that suchprofessionals look into light sources several times aworking dayaccumulatingexposuretoseveralseconds. Inthissituation,theblueradiance isthecriticalfactorforBLH(the higher the radiance in the relevant action spectrum, the higher the likelihood that light hitsphotopigments(withsufficientenergy)andcausesdamages.Lookingstraightatalightsource(caseB)isalsoingeneralsafefordiffuseandwarmwhitelightsources,likefrostedorwhitediffusinglamps.Yet,cautionisadvisableforcoolwhiteorblue,bright(highintensity),pointlikelightsource,forinstanceanincandescentfilament,electricarcoranLEDdie,evenanLEDdiebehindthelensofadirectionallamp.Suchpointlikesourcesareprojectedontheretinaasaconcentratedlightspotandcandamagethatspotontheretinawhentheintensityishighenoughandthespectrumcontainsbluelightincongruencewiththebluelighthazardactionspectrumcurve.Bothcasesareherediscussedinmoredetail:DataoncaseA:Lookingatanilluminatedscene(irradiance)InAnnex2anoverviewisgivenofthespectraldataofvariouslightsourcesindirectcomparisonwitheachother.Fromthesespectra,thebluehazardirradiancevaluesEBwerecalculatedusingthestandardbluelighthazard(BLH)actioncurve.InFigure2(nextpage)anoverview isgivenoftheEBvaluesofthedifferent lamptypes. It isclearthatallsourcesofasimilarcolourtemperature(TcinKelvin)haveasimilarEBvalue.Thisisbecausetheblueportionhasafixedrelationtotheothercolourstomakethecolourwhite.


Figure3:ComparisonofEBvaluesofthedifferentlamptypesanddaylight.Inorder tobetter comparewith theeffectofdaylight, itmustbenoted thatdaylightnormallyprovidesilluminancelevelsthataremuchhigherthan500lux.Figure3showsthecomparisonoftheEBofanumberof light sourcesat500 lux, comparedwithdaylightat5000 lux,which isan average value formoderatelatitudes.Sometypicallamps@500luxcomparedwithoutdoorlighting@5000lux

Figure4:comparisonof irradiancevaluesofsome lamptypesat500 lux(typicalfor indoor)withdaylightat5000 lux(typicalforoutdoorlighting)Theactualoutdoorilluminancevaluecanvaryoverawiderange,upto50.000luxforasunnysummerdayonmoderatelatitudesandeven100.000luxattropicallatitudes.Thisshowsthatthequantityofbluelightofanyindoorgenerallightingcomparedtooutdoorconditionsislowtoverylow.


DataoncaseB:Lookingatalightsource(radiance)InordertocomparethelightsourcesforcaseB,werefertothestandard(EN62471)asdescribedabove.Inthesestandardsadifferenceismadebetweenlargesourcesandsmallsources.Theimageofasmallsource(4,000,000


Theresultsareplottedinthenexttwofigures:BlueLightRadianceLBofdiffusesources

Figure5:BlueLightradianceLBforseveralcommonlowluminancelightsources:incandescentlamps,fluorescentlamps,andtheirLEDreplacements.Asareference,alsoaclearincandescentlampisplottedBlueLightRadianceLBofsometypicalpointlikesources

Figure6:BlueLightRadianceLBforseveralhighluminancelightsources:halogenlamps,highintensitydischargelamps,andtheirLEDreplacements.(note:scalediffersfromFigure4)

010002000300040005000600070008000900010000

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/msr


ConclusionsonBlueLightRadiancefigures:- Theblue light radiance LBofdiffuse light sources is relatively low.Assigning the light source to risk

groups (EN 62471)based on the LB values, reveals thatmostof them fall intoRG 0, at higher colortemperature(4000K)somemayjustfallinRG1withmaximumexposuretimesofmorethananhour.Pleasenotethatthisexposuretimereferstoaclosedirectgazeintothesource.Innormalconditionsofuse,wheredistancesaremuchbigger than themeasuring conditionof200mm to the source, this iscompletelysafe.Inaddition,inareflexivereactionhumansturnawayfrombrightlightsources,sothatsuchexposuretimesarenotreachable.

- AllpointlikelightsourcesevaluatedherefallinRG1andareconsideredtobesafebythestandardanddonot requireadditionalwarningmarkings,butprolongeddirect viewingdirectly into these sourcesmustbeavoidedespeciallyatshortdistances.Maximumexposuretimesforthelampsshownhereare200secor longer,butasalreadymentionedearlier,peoplewillclose theireyesor lookaway insuchcases(instinctiveaversionreaction).ThisholdsforthehighluminanceLEDsources justasmuchasforthehighluminancelightsourcesthatarelongeronthemarket.


Annex4:Terminologyexplainedquantity symbol unit explanation

irradiance Erad W/m radiantpowerperareaarrivingonacertainplane

illuminance E lux irradiance,spectrallyweightedwiththephotopiceyesensitivitycurve

bluehazardirradiance

EB W/m irradiance,spectrallyweightedwiththebluehazardcurve

radiance Lrad W/msr radiantintensityperareaemittedfromasource

luminance L cd/m radiance,spectrallyweightedwiththephotopiceyesensitivitycurve

bluehazardradiance LB W/msr radiance,spectrallyweightedwiththebluehazardcurve

Table3:overviewofunitsofmeasurerelevantinthisarticle

Radiant flux, irradiance,radiant intensityandradiancerefertoradiationacrossallwavelengths.Luminousflux,illuminance,luminousintensityandluminancegivetheanaloguedimensions,butlimitedtothevisiblespectrum (spectrally weighted with the visual sensitivity curve of the human eye to light of differentwavelengths).


Table4:overviewrisksgroups(takenfromEN62471:2006)


PrinciplesbehindmeasurementsEN62471:relevancylarge/smallsources:

EN62471:differentmethodsformeasuringsmall/largesources

large source (radiance of source relevant)

small source (irradiance at pupil relevant)

very short exposure (< .25 s)small (point) source min = 0,0017 rd (~0.1)due to intrinsic unsharpness

intermediate exposure (10 s 100 s)small source eff = 0,011 rd (~0.63)due to rapid eye movement

long exposure (> 10000 s)small source eff = 0,1 rd (~ 5.7)due to task oriented eye movement

the smallest image that can be formed on the retina of a still eye is limited to a minimum value, min = 1,7 mrad (at exposure < 0,25 seconds = blink ref lex time)

1 1,7mrad 2 11 mrad @ 200mm

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measurementFOV

at times greater than about 0,25 seconds, rapid eye movements begin to smear the image of point-like source over a larger angle, called eff = 11 mrad

a light source subtending an angle less than 11mrad is defined as a small source

3 11 mrad @ 500lx 4 100 mrad

at > 100 seconds, the image is further spread due to task depended eye movements,resulting in an maximal angular subtense max = 100 mrad (taken at exposure times > 10000 s)

Eye movements & angular subtense

Measurement Field of View @ 200mm & @ distance producing 500 lx


ActinicUVandBlueLightHazardactionspectrumTheactioncurvesforUVandBluehazardaregivingaweightingfactortothespectralradiationintherelevantpartofthespectrum:

Bymultiplyingtheactioncurvevalueswiththe(normalized)spectraldataofUVand/orlightsources,comparativefactorsareobtainedtocomparethesesourcesonthementionedhazards.

Annex5:OverviewoflampsdiscussedinthispaperThelampdatapresentedinthispaperarerepresentativefortheportfoliooftheELCcompanies

Usedproductnameindocument Technology Shape WattageColourtemperatureTc[K]

HaloA6028WMVburner2700KE27MV Halogen230V A60bulb 28 2700HaloA6040WLVburner2830KE27MV Halogen12V A60bulb 40 2830HaloMR1645W24DIRC2850KGU5.3LV Halogen12VIRcoated MR16reflector 45 2850HaloCaps28W2800KUVblockG9MV Halogen230VUVreduced capsule 28 2800HaloA6025W2600KE27MV Halogen230V A60bulb 25 2600ESbulbT608272620KE27MV CompactFluo T60bulb 11 2620ESburner8W8272700KE27MV CompactFluo bendedtubes 8 2700IncandA6060W2700KfrostedE27MV Incandescent A60bulb 60 2700LEDA606W2700KE27MV LED A60bulb 6 2700LEDMR167W40D2700KGU10MV LED MR16reflector 7 2700LEDMR167W40D4200KGU10MV LED MR16reflector 7 4200LEDK6012W2700KE27MV LEDremotephosphor K60bulb 12 2700TLD18W/840 Fluorescent26mm Tube 18 4000T554W/6500K Fluorescent16mm Tube 54 6500T524W/4000K Fluorescent16mm Tube 54 4000T524W/17000K Fluorescent16mm Tube 24 15000TLED11W/4000K LEDtube26mm Tube 11 4000LEDlamp6500K350lm LED A60bulb 6 6500R7shalogen500W Halogen230V doubleended 500 2700

Disclaimer:WhileELC/CELMAhavemadeeveryattempttoensuretheaccuracyoftheinformationcontainedherein,ELC/CELMAdonotacceptresponsibilityorliabilityforanyusageofthisdata.

Optical Safety LED Lighting

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