UNITEDSTATESENVIRONMENTALPROTECTIONAGENCYREGION5-AUG1 92014TheHonorableRickSnyderGovernorofMichiganP.O.Box30013Lansing,Michigan48909DearGovernorSnyder:77WESTJACKSONBOULEVARDCHICAGO,IL60604-3590REPLYTOTHEATTENTIONOF:ThankyouforyourrecommendationsdatedOctober31,2013,ofairqualitydesignationsforthe2012revisedprimarymmualfineparticle(PM2.s)NationalAmbientAirQualityStandard(NAAQS)throughoutMichigan.IappreciatetheinformationMichigansharedwiththeU.S.EnvironmentalProtectionAgencyaswemoveforwardtoimprovePM2.sairquality.ThisletteristonotifyyouofEPA'spreliminaryresponsetoMichigan'srecommendationandtoinformyouofourapproachforcompletingtheinitialareadesignationsforthe2012revisedprimaryannualPM2.sstandard.OnDecember14,2012,EPApromulgatedarevisedprimaryannualPM2.sNAAQS(78FR3086,January15,2013).lnthataction,EPArevisedtheprimm·yannualPM2.sstandard,strengtheningitfrom15.0microgramspercubicmeter()lg/m3)to12.0)lg/m3;retainedtheexisting24-hourPM2.sstandardat35)lg/m3;retainedtheexisting24-hourPM10(coarseparticle)standardat150)lglm3;andretainedthecurrentsuiteofsecondaryPMstandards.EPArevisedtheprimaryannualPM2.sstandardbasedonanintegratedassessmentofanextensivebodyofnewscientificevidence,whichsubstantiallystrengthensourbodyofknowledgeregardingPM2.s-relatedhealtheffects.TherevisedprimaryannualPM2.sstandardwillprovideincreasedprotectionforchildren,olderadults,personswithpre-existingheartandlungdisease,andotherat-riskpopulationsagainstanarrayofPM2.s-relatedadversehealtheffects,includingprematuremortality,increasedhospitaladmissionsandemergencydepartmentvisits,anddevelopmentandexacerbationofchronicrespiratorydisease.Historyshowsusthatbetterhealthandcleanerairgohand-in-handwitheconomicgrowth.Workingcloselywiththestatesandtribes,EPAisimplementingthestandardsusingacommonsenseapproachthatimprovesairqualityandminimizestheburdenonstate,local,andtribalgovernments.Aspartofthisprocess,EPAisworkingwiththestatesandtribestoidentifyareasinthecountrythatmeetthestandardsandthosethatneedtotakestepstoreducePM2.sairpollution.Withinoneyearofpromulgationofaneworrevisedairqualitystandard,theCleanAirActrequirestheGovernorofeachstatetosubmittoEPAalistofallareasinthestate,withadesignationrecommendationforeacharea.Asafirststepinimplementingthe2012annualPM2.sstandard,Governorsweretosubmittheirdesignationrecommendations,includingappropriateareaboundaries,byDecember13,2013.Recycled/Recyclable•PrintedwithVegetableOilBasedInkson100%RecycledPaper(100%Post-Consumer)AsrequiredbytheCleanAirAct,EPAthenpromulgatesdesignationsforallareasacrossthecountry.EPAdesignatesanareaas"nonattainrnent"ifitisviolatingthe2012annualPM2.sNAAQSorifitiscontributingtoaviolationoftheNAAQSinanearbyarea.ConsistentwithdesignationsforpreviousPM2.sstandards,EPAintendstouseadesignationcategoryof"unclassifiable/attainrnent"forareasthataremonitoringattainmentordonothavemonitors,butforwhichEPAhasreasontobelievearelikelyattainmentandarenotcontributingtonearbyviolations.Additionally,EPAintendstodesignateas"unclassifiable"thoseareaswhereEPAcannotdeterminebasedonavailableinformationwhethertheareaismeetingtheNAAQSorwhereEPAhasnotdeterminedthattheareacontributestoanearbyviolation.Atthistime,EPAisproceedingwithinitialareadesignationsusingquality-assured,certifiedairqualitymonitoringdatafrom2011to2013.EPAhasreviewedtheannualPM2.sdesignationrecommendationssubmittedbyMichiganonOctober31,2013,andhavereviewedtherelevanttechnicalinformation,including2011-2013airqualitydata.Thesedatadonotindicateanyviolationofthe2012annualPM2sNAAQSinMichiganorcontributiontoanynearbyarea.Accordingly,EPAintendstodesignatetheentirestateofMichiganasunclassifiable/attainment.EPAwillmakeitsproposeddesignationdecisionsandsupportingdocumentationavailabletothegeneralpublicforreviewandcomment.Wewillbeannouncinga30-daypubliccommentperiodshortlyintheFederalRegister.Afterconsideringanyadditionalinformationwereceive,EPAplanstopromulgatefmalannualPM2.sdesignationsinDecemberof2014.EPAiscommittedtoworkingwiththestatesandtribestosharetheresponsibilityofreducingPM2.sairpollution.Currentandupcomingfederalstandardsandsafeguards-includingpollutionreductionrulesforpowerplants,vehicles,andfuels-willensuresteadyprogresstoreducePM2.s-formingpollutionandwillprotectpublichealthincommunitiesacrossthecountry.Welookforwardtoacontinueddialoguewithyouandyourstaffasweworktogethertoimplementthe2012annualPM2.sstandard.Ifyouanyquestions,pleasecontactmeoryourstaffmaycontactRonnaBeckmannorEileenDeamer,theRegion5IntergovernmentalLiaisons,at(312)886-3000.Sincerely,SusanHedmanRegionalAdministratorcc:DanWyantDirector,MichiganDepartmentofEnvironmentalQualityLynnFiedlerActingChief,AirQualityDivisionMichiganDepartmentofEnvironmentalQuality