# UNITED

STATES ENVIRONMENTAL

PROTECTION

AGENCY REGION

III 1650

Arch

Street Philadelphia,

Pennsylvania

19103 DATE:

25 August

2011 SUBJECT:

Technical

Support Document

Regarding

Ozone Monitoring

Data— 

# District

of Columbia,

Maryland,

and Virginia; Determination

of Attainment

of the

1997

8- Hour Ozone National

Ambient

Air Quality Standard

and Clean

Data Determination

for

the Washington,

DC-MD-VA

8-Hour

Ozone Moderate Nonattainment

Area FROM:

ASenior

Air Quality Planning

Specialist Office

of Air Program

Planning TO:

Fil /1 THRU:

‘Cfistina Fernandez,

Associate

irector Office

of Air Program

Planning This document

provides

a technical

review

of the

air quality monitoring

data

used

to support

the Environmental

Protection

Agency’s

(EPA’

s) proposed determination

that

the Washington,

DCMD-VA

8-hour

ozone moderate nonattainment

area

(the Washington

Area)

has attained

the 1997 ozone national

ambient

air quality standard (NAAQS)

by

its statutory attainment

date

and EPA’s proposed

clean

data determination

for

the Washington

Area. I. BACKGROUND This Washington

Area includes

the District

of Columbia;

Arlington,

Fairfax, Loudoun,

and Prince William

Counties

and

the cities

of Alexandria,

Fairfax,

Falls Church, Manassas,

and Manassas

Park

in Virginia;

and Calvert,

Charles, Frederick, Montgomery,

and Prince George’s Counties

in Maryland.

The Washington

Area

was classified

as

a moderate nonattainment

area. See

40 CFR 81.309,

81.321

and 81.347. Moderate

areas

are required

to attain

the

1997 8-hour ozone NAAQS

by

no later

than

June

15, 2010.

$c,

40 CFR

5 1.903. II. EVALUATION

OF AIR QUALITY MONITORING

DATA A. Data Requirements The criteria

for determining

if

an area

is attaining

the

1997 8-hour

ozone NAAQS

are

set

out

in 40 CFR

50.10

and appendix

I. The determination

is based

on

the most recent

three complete, consecutive

calendar

years

of quality-assured

air quality monitoring

data

at

all ozone monitoringsitesinthearea.Toattainthisstandard,ateachmonitortheannualfourth-highdailymaximum8-hourozoneconcentrationsmeasuredaveragedoverthethree-yearperiod(themonitoringsitesozonedesignvalue)mustnotexceedtheozonestandard.Thelevelofthe19978-hourNAAQSforozoneis0.08partspermillion(ppm).Basedonanozonedataroundingconventiondescribedin40CFRpart50,appendixI,thestandardismetifozonedesignvalueis0.084ppm(84partsperbillion)orlower.Whenthedesignvalueislessthanorequalto0.084ppmateachmonitoringsitewithinthearea,theareameetstheNAAQS.Thedatamustbecollectedandquality-assuredinaccordancewith40CFRpart58,andmustberecordedinEPA’sAirQualitySystem(AQS).Thedatasupportingattainmentofthestandardmustbecompleteinaccordancewith40CFRpart50,appendixI.Thedatacompletenessrequirementismetwhenthepercentofdayswithvalidambientmonitoringdata,averagedoverthreeyears,isgreaterthan90%,andnosingleyearhaslessthan75%datacompleteness.FortheWashingtonArea,theozoneseasonextendsfromthebeginningofAprilthroughtheendofOctober.Acompleteozoneseasonconsistsof214monitoringdays.B.CertifiedAirQualityMonitoringData,2007-2009TheDistrictofColumbia,theStateofMaryland,andtheCommonwealthofVirginia(“theStates”)submittedcomplete,qualityassuredairqualitymonitoringdataintoAQS.TheStatesthencertifiedthatdata.AttachedaretwoAQSreportscontaining8-hourozonedatafortheWashingtonAreafor2007to2009.Table1,below,summarizesthosereports.Table1:2007-2009WashingtonArea8-HourOzoneDesignValues&DataCompleteness4thHighestValue2007-2009PercentCompleteness(ppm)Design(validmonitoreddays/requireddays)StateCountySiteIDValue2007-2009200720082009200720082009(ppm)averageCalvert2400900110.0790.0770.0680.07493889492Charles2401700100.0830.0780.0660.0751009610099MarylandFrederick2402100370.0860.0750.0690.076100989798Montgomery2403130010.0880.0760.0700.078648998842403300300.0840.0810.0700.078100978895PrinceGeorge’s2403380030.0880.0790.0670.078949910098Arlington5101300200.0880.0840.0670.0791001001001005105900050.0780.0780.0650.07310098100995105900180.0880.0850.0690.080100100100100Fairfax5105900300.0850.0850.0700.080100999999Virginia5105910050.0840.0820.0700.0789981100935105950010.0830.0800.0680.07799100100100Loudoun5110710050.0860.0790.0680.0771009710099PrinceWilliam5115300090.0760.0740.0640.071979810098AlexandriaCity5151000090.0840.0750.0660.075999497971100100250.0840.0750.0720.077981008895DistrictofDistrictof1100100410.0890.0820.0640.07810010099100ColumbiaColumbia1100100430.0870.0840.0710.080991001001002AsshowninTable1,above,all2007-2009designvaluesarebelow0.084ppm.Allbutonemonitormeetsthedatacompletenessrequirements.DataCompletenessIssuesforMontgomeryCounty,MarylandAsseeninTable1,above,thethreeyearaveragecompletenessformonitor240313001inMontgomeryCounty,MDis84%,whichisbelowtherequired90%.In2007,thatmonitorrecordeddatafor138oftherequired214days,whichis64%datacapture.AccordingtoappendixI,atleast75%datacaptureisrequiredeachyear.Foryearswherethereislessthan75%datacompleteness,certaindatasubstitutionisallowed.“Whencomputingwhethertheminimumdatacompletenessrequirementshavebeenmet,meteorologicalorambientdatamaybesufficienttodemonstratethatmeteorologicalconditionsonmissingdayswerenotconducivetoconcentrationsabovethelevelofthestandard.Missingdaysassumedlessthanthelevelofthestandardarecountedforthepurposeofmeetingthedatacompletenessrequirement,subjecttotheapprovaloftheappropriateRegionalAdministrator.”OnMarch4,2011,theMarylandDepartmentoftheEnvironment(MDE),submittedadatasubstitutionanalysisformonitor240313001forthe2007ozoneseason.Themonitorwasshutdownfor75days(April1toJune14)duetoreplacementofatraileratthemonitoringlocation.MDE’sanalysis,datedJanuary11,2011,usesthedatasubstitutionprovisionsofappendixIto40CFRpart50todeterminethat75dayshadmetrologicalconditionsthatwerenotconducivetoozoneformationabovethelevelofthe2008ozoneNAAQS,0.075ppm.MDErequestedthatmissingmonitoringdataforthose75daysbecountedindeterminingdatacompletenessfor2007.InaletterdatedMay4,2011,EPADeputyRegionalAdministratorWilliamC.Early,actingonbehalfofRegionalAdministratorShawnM.Garvin,approvedthatMDE’sdatasubstitutionanalysisfor57ofthe75days.MDE’sdatasubstitutionanalysisandEPA’sapprovalletterareattached.2007-2009DataComparisontoNAAQSAsshowninTable1,all2007-20098-hourozonedesignvaluesfortheWashingtonAreaare0.084ppmorless.Thedatasubstitutionanalysis,describedabove,formonitor240313001resultsinanadditional57daysofdata,foratotalof195validdays.Withtheapproveddatasubstitution,datacompletenessfor2007is91%,witha2007-2009three-yearaveragecompletenessof93%.Thus,whenconsideringthedatasubstitutionanalysisformonitor240313001,allmonitorsmeetthecompletenesscriteria.Therefore,theWashingtonAreameetsthe19978-hourozoneNAAQS,considering2007-2009data.C.CertifiedAirQualityMonitoringData,2008-2010TheStateshaveallcertifiedtheir2010data.AttachedaretwoAQSreportscontaining8-hourozonedatafortheWashingtonAreafor2008to2010.AsshowninTable2,below,2008-20108-hourozonedesignvaluesfortheWashingtonAreaare0.084ppmorless.However,fourmonitorsinFairfaxCounty,VAhavelowdatacompletenessin2010because,asdescribedinmoredetail,below,thesemonitorswereshutdown.3Table2:2008-2010WashingtonArea8-HourOzoneDesignValues&DataCompletenessNote:“SD”indicatesthatthemonitorwasshutdown.MonitorShutdownsinFairfaxCounty,VirginiaDuetothedecisionbytheFairfaxCountygovernmenttonolongerprovidefundingtotheFairfaxCountyHealthDepartment(FCDH)foroperatingandmaintainingtheambientairmonitoringstationsinFairfaxCounty,FCHDceasedtheoperationandmaintenanceoftheircounty-wideozonemonitoringnetwork.Monitors510590005,510591005,and510595001wereshutdownattheendof2009.Therefore,thereisno2010dataforthesethreemonitors.Monitor510590018wasshutdownonJuly1,2010.VirginiaDepartmentofEnvironmentalQuality(VADEQ)workedwithEPApriortoFCHDshuttingdownthesemonitors.BecausetheWashingtonAreahasmoreozonemonitoringsitesthanminimallyrequired,andbecauseVADEQperformedananalysisonthesitesthatwerebeingshutdownshowingastrongcorrelationbetweentheambientozonedatacollectedattheFairfaxCountyozonesitestargetedfordiscontinuationandexistingVADEQozoneairmonitoringsitescurrentlyoperatinginproximitytotheFairfaxCountyarea,EPAapprovedtheshutdownsinVADEQ’s2010AnnualNetworkPlan.2008-2010DataComparisontoNAAQSEPAapprovedtheshutdownoffourmonitorsinFairfaxCounty,monitors510590005,510591005,510595001,and510590018.Therefore,EPAwillnotconsiderthesemonitorsforcomparisontotheNAAQSin2010.AsshowninTable2,all2008-20108-hourozonedesignvaluesfortheremainingmonitorsintheWashingtonAreaare0.084ppmorless.Thesemonitorsallmeetthecompletenesscriteria.Therefore,theWashingtonAreacontinuestomeet4thHighestValue2008-2010PercentCompleteness(ppm)Design(validmonitoreddays/requireddays)StateCountySiteIDValue2008-2010200820092010200820092010(ppm)Calvert2400900110.0770.0680.0870.07788949793Charles2401700100.0780.0660.0820.0759610010099MarylandFrederick2402100370.0750.0690.0830.076989710098Montgomery2403130010.0760.0700.0770.0748998929324033003000810.0700.0850.07997889593PrinceGeorge’s2403380030.0790.0670.0850.077991009799Arlington5101300200.0840.0670.0870.07910010084955l05900050.0780.0659810005l05900l80.0850.0690.0680.0741001004080Fairfax5105900300.0850.0700.0890.08199998594Virginia5los9oos0.0820.07081100060510595001SD0.0800.068100100067Loudoun5110710050.0790.0680.0780.075971008494PrinceWilliarn5115300090.0740.0640.0730.070981008594AlexandriaCity5151000090.0750.0660.0810.074949783911100100250.0750.0720.0790.075100888390DistrictofDistrictofColumbiaColumbia1100100410.0820.0640.0860.07710099841100100430.0840.0710.0820.07910010085954the19978-hourozoneNAAQS,considering2008-2010data.Attachments:-EPAAQSQuickLookReport(AMP45O),datedDecember29,2010,containing2007-2009ozoneairqualitydataforDistrictofColumbiaandMarylandportionsoftheWashingtonArea,andpartoftheVirginiaportionoftheWashingtonArea.-EPAAQSQuickLookReport(AMP45O),datedDecember29,2010,containing2007-2009ozoneairqualitydatafortheremainingpartoftheVirginiaportionoftheWashingtonArea.-May4,2011EPAlettertoMDEapprovingMDE’sJanuary11,2011DataSubstitutionAnalysis,submittedtoEPAbyletterdatedMarch4,2011.-MDE’sJanuary11,2011DataSubstitutionAnalysisforAQSSiteID:240313001,submittedviacoverletterdatedMarch4,2011.-EPAAQSQuickLookReport(AMP45O),datedMay27,2011,containing2008-2010ozoneairqualitydataforDistrictofColumbiaandportionsVirginiaoftheWashingtonArea,andpartoftheMarylandportionoftheWashingtonArea.-EPAAQSQuickLookReport(AMP45O),datedMay27,2011,containing2008-2010ozoneairqualitydatafortheremainingpartoftheMarylandportionoftheWashingtonArea.5