### MEMORANDUM UNITED STATES ENVIRONMENTAL PROTECTION AGENCY RESEARCH TRIANGLE PARK, NC 27711



## JAN Z Z2015 OFFICE OF AIR QUALITY PLANNING AND STANDARDS



### SUBJECT: Information onthe Interstate Transport "GoodNeighbor" Provision for the 2008 Ozone National Ambient Air Quality Standards (NAAQS) under CleanAir Act (CAA) Section 110(a)(2)(D)(i ) 

### FROM: Stephen D. Pag Director 

### TO: Regional Air Division Directors, Regions 1 - 10
Thepurpose ofthis memorandum is to provide informationto states regarding state implementation plans (SIPs) to address the interstate transport "GoodNeighbor" Provision ofthe CleanAirAct (CAA) as itpertains to the 2008 ozoneNational AmbientAir Quality Standards (NAAQS). This information consists of:

• Discussion ofelements thathave beenusedpreviouslyto address interstate transport, and • The EPA's preliminary air quality modeling data for ozone for the year 2018.
The EPA anticipates that this information, together with additional steps described below, will be helpful to states developing "GoodNeighbor" SIPs for the 2008 ozone NAAQS. The EPA and states are behind schedule in addressingthe "GoodNeighbor" Provision for the 2008 ozone standards, due to factors such as the EPA's reconsideration ofthe standards and protracted litigation relatedto previous actions [mostrecently the Cross-State Air PollutionRule (CSAPR)] underthe "GoodNeighbor" Provision. This document is part oftheprocess ofworking with states to offer support and information to enable the EPA and states to move forward to address the requirements ofthe "GoodNeighbor" Provision for this NAAQS as soon as possible.
In additionto the information being shared today, the EPA will hold a webinar in early February and a workshop inthe spring of2015. The webinar will focus onthe content ofthis memo and the attached preliminary air quality modeling data. Forthe workshop, the EPAplans to facilitate discussions with states on: (1) available emission controls; (2) potential state-by-state electric generating unit (EGU) nitrogen oxides (NOx) reductions based onthose controls; and (3) potential EGU emissions budgets informed bythose reductions. More information onthe webinar and workshop will be forthcoming.
The EPA's goal is to provide information andto initiate discussions thatwill inform state development and EPAreview of"GoodNeighbor" SIPs, and, where appropriate, to facilitate state efforts to supplement orresubmittheir "GoodNeighbor" SIPs. Atthis time, there are a number ofstates that may nothave submitted "GoodNeighbor" SIPs for the 2008 ozone NAAQS. In addition, there are a number

Internet Address (URL) • http://www.epa.gov Recycled/Recyclable • Printed wHh Vegetable 011 Based Inks on Recycled Paper (Minimum 25% Postconsumer)

### ofpending "Good Neighbor" SIPs for the 2008 ozone NAAQS that the EPAwill review and take action on. While our goal is to facilitate SIP development, the EPA also recognizes its backstop role inthe SIP development process-thatis, our obligation to develop and promulgate federal**imp~ementation** 

### plans, as appropriate. Weplanto take this action, ifnecessary. It

### is our intention that any federal rule developed to satisfy this obligation would provide ample opportunity for states to pursue alternatives.
The "Good Neighbor" Provision

Under CAA sections llO(a)(l) and 110(a)(2), each state 1

### is required to submit a SIP2 

### thatprovides for the implementation, maintenance and enforcement ofeachprimary or secondary NAAQS. Moreover, section 11O(a)(1) requires each state to make this new SIP submission within 3 years after promulgation ofa new or revised NAAQS.3 

### This type ofSIP submission is commonlyreferredto as an "infrastructure SIP." The conceptual purpose ofan infrastructure SIP submission is to assure that the state's SIP contains the necessary structural requirements for the implementation ofthe new or revised NAAQS, whether by establishing that the SIP already contains or sufficiently addresses the necessaryprovisions, or by making a substantive SIP revision to update the SIP.
CAA section 110(a)(2)(D)(i)(I) requires each state in its SIP to prohibit emissions thatwill significantly contribute to nonattainment ofa NAAQS, or interfere with maintenance ofa NAAQS, in a downwind state. Under section 110(a)(2)(D)(i)(I), each state is required to submit to the EPA new or revised SIPs that "contain adequate provisions- prohibiting, consistent withthe provisions ofthis subchapter, any source or other type ofemissions activity withinthe state from emitting any air pollutant in amounts which will

. .. contribute significantly to nonattainment in, or interfere with maintenance by, any other state with respect to any suchnational primary or secondary ambient air quality standard." Forpurposes ofthis document, we refer to section 110(a)(2)(D)(i)(I) as the "GoodNeighborProvision" and to SIP revisions addressing this requirement as "GoodNeighbor SIPs."
Elements That Have Been Used Previously to Address the' Good Neighbor" Provision
The EPAnotes that a consistent framework for addressing transport for certainNAAQS, involving a number ofbasic steps, has been developed in several previous federal rulemakings.4 

### These basic steps include: (1) identifying downwind air quality problems, (2) identifying upwind states that contribute enoughto**t~ose** 

### downwind air quality problems to warrant further review and analysis, (3) identifying

1 The term "state" as used in this memorandum has the same meaning as provided in CAA section 302(d). These CAA sections and this information may also apply, as appropriate under the Tribal Authority Rule (TAR) in 40 CFRpart49, to an Indian tribe thatreceives a determination ofeligibility for treatment in a similar manner as a state for purposes of administering a tribal air quality management program under section llO(a}l>fthe CAA. Tribes should look to the TAR and engage theirrespective EPAregional offices in discussing howthis information may impactthe development and approvability oftheir tribal implementation plans (TIPs). We encourage states to provide outreach and engage in discussions withtribes abouttheir SIPs as they are being developed. 2 In the CAA and in this memorandum, "plan," "SIP" and "TIP" may, depending on context, refer either to (i) all or part of the existing state (or tribal) implementationplan (i.e., the collection ofall submissions previously approved bythe EPA as meeting CAA requirements) or (ii) a submission that adds to ormodifies the existingplan as directed by section llO(a)(l). 3 The Administrator may specifY a shorterperiod. 4See for example, Finding ofSignificant Contribution and Rulemaking for Certain States in the Ozone Transport Assessment Group Region for Purposes ofReducing Regional Transport ofOzone. 63 FR57356 (October 27, 1998); Clean Air Interstate Rule (CAIR) Final Rule. 70 FR25162 (May 12, 2005); CSAPRFinal Rule. 76 FR48208 (August 8, 2011)

. 2

### the emissions reductions necessaryto prevent an identified upwind state from contributing significantly to those downwind air qualityproblems and (4) adoption ofpermanent and enforceable measures needed to achieve those emissions reductions.
Efforts to address ozone transportbythe EPA and states under the "GoodNeighbor" Provisionhave focused onreductions ofNOxas the precursorpollutant for which emissions inupwind states have the greatest impacts ontransported ozone.5


### In CSAPR, downwind air quality problems were assessed based onmodeled future air quality concentrations for a year aligned with attainment deadlines for a particularNAAQS. The assessment of future air quality conditions generally accounted for on-the-books emissions reductions6 

### andthe most up-to-date forecast offuture baseline emissions. The locations ofdownwind air quality problems were identified as those receptors that were projected to be unable to attain or maintain the standard. More detail onthe methods for identifyingproblemreceptors in CSAPRis contained inthe attachment.
CSAPRused a screening threshold (1 percent ofthe NAAQS) to identify contributing upwind states warranting further review and analysis. States whose air quality impact1 to at least one downwind problem receptor was greater than or equal to the threshold were identified as needing further evaluation for actions to address transport. States whose air quality impacts to all downwindproblem receptors were belowthis threshold were identified as states notrequiring further evaluation for actions to address transport-that is, these states had no emissions reduction obligation under the "GoodNeighbor" Provision.
In orderto quantify emissions reductions needed to eliminate significant contributions to a downwind air quality problem, CSAPR's apportionment ofresponsibility evaluated air quality and included consideration ofcost, an approach thatwas recently upheld bythe U.S. Supreme Court.8 

### The selection ofcost criteriawas informed by air quality considerations. For example, the approach in CSAPRfor sulfur dioxide contributions to fine particulate matter (PM2

.s) placed states into two groups based on differing air quality considerations at downwindreceptors. For states within each group, however, a uniform cost level was usedto determine needed emissions reductions.

The EPA's preliminary air quality modeling analysis 

### (see attachment and the Air Quality Modeling Technical Support Document for the 2008 Ozone NAAQS Transport Assessmentlocated at 

### www.epa.gov/airtransport) applies the CSAPR approach to the 2008 ozone NAAQS, including the approach for identifying nonattainment and maintenance receptors and for identifying upwind states that contribute to these receptors based onthe 1percent screeningthreshold. Following the CSAPR approach, a state could either demonstrate that its contribution is belowthe screening threshold, or it could evaluate the scope ofits transport obligation and identify measures to achieve any needed emissions reductions. The discussions at the spring 2015 workshop are intended to help states with their evaluation ofsuch emissions reductions.

5 See discussion in preamble to the CSAPRFinal Rule. 76 FR48222 (August 8, 2011). 6 The exception being CAIR, which CSAPRwas designedto replace andtherefore was not considered on-the-books. 7 For ozone the impacts would include those from volatile organic compounds (VOC) and NOx, and from all sectors. 8 EPA v. EMEHomer City Generation, L.P., 134 S. Ct. 1584, 1606-07 (2014). 

### 3

### CSAPR and its predecessortransport rules, the NOx SIP Call and CAIR, were designed to address the collective contributions from the 37 states inthe EasternU.S. and were not formally evaluated for applicability to the 11 states in the Western U.S. 9 

### The EPA's preliminary modeling indicates that most western states contribute less than 1percent to downwind nonattainment ormaintenance receptors, a level the EPA considered to notneed further evaluation for actions to address transport in CSAPR. There are a fewreceptors in the Westwhere 1to 3 western states may contribute amounts potentially exceeding the 1percentthreshold (See Technical SupportDocument). Due to the possibilitythat additional considerations may impact the EPA's and state's evaluation oftransportfrom these potentially linked states in the Western U

.S., we expectthatthe EPA and states will continue to evaluate these westerntransport linkages (not included in the attachment) on a case-by-case basis. We recommend that states consult withtheir EPAregional offices regarding these specific situations.
For Further Information
Ifyouhave any questions concerningthis information, please contact Tim Smith, at (919) 541-4718, smith.tim@epa.gov, or Gobeail McKinley, at (919) 541-5246, mckinley.gobeail@epa.gov.
Attachment

9 For the purposes ofthis information document, we include the 37 states and the District ofColumbia in the region from Texas northwardto NorthDakota and eastwardto the East Coast as comprising the Eastern U

.S. The WesternU.S. refers to the 11 states in the contiguous U.S. west ofthose states (AZ, CA, CO, ID, MT, NM, NV, OR, UT, WA and WY).

4

### Attachment

Air Quality Modeling Results 

### A. Background The EPA performed photochemical air quality modelingto project ozone concentrations at air quality monitoring sites to 2018, the moderate area attainment date for the 2008 ozoneNational Ambient Air Quality Standards (NAAQS), and to estimate state-by-state contributions to those 2018 concentrations. We thenusedthe air quality modeling results, and the methods we used for Cross-State Air PollutionRule (CSAPR), to identify ozone monitoring sites expectedto be nonattainment or maintenance receptors for the 2008 ozoneNAAQS in 2018. We used the contribution informationto quantify projected interstate contributions from emissions ineachupwind state to ozone concentrations at each identified 2018 nonattainment and maintenance receptor in downwind states. The EPA's air quality modeling used the 2011-based air quality modelingplatform. This platform includes emissions for a 2011 base year and a 2018 future base case as well as meteorology for 2011. The 2011 meteorology was used in air quality model simulations for both 2011 and 2018. We selected 2011 as the base year because it reflectedthe most currentNational Emissions Inventory (NEI) available. Details on the construct and evaluation ofthe 2011-based air quality modeling platform are provided inthe Air Quality Modeling Technical Support Documentfor the 2008 OzoneNAAQS Transport Assessment (AQMTSD). The 2011 base year emissions inthe 2011-based air quality modelingplatform were derived from the 2011 NEI, as described inthe Technical SupportDocument: Preparation ofEmissions Inventories for the Version 6.0, 2011 Emissions Modeling Platform. 10 

### This document also describes the control and growth assumptions by source type that were used to create the 2018 base case emissions inventory. 11 

### The EPAreleased the 2011 and 2018 emissions inventory for public review on

10 Available on the EPA's website at: http://www.epa.gov/ttnchiel/emch. 11 For electric generating units (EGUs), the 2018 base case emissions were obtained from the Integrated Planning Model (IPM version 5.13, http://www.epa.gov/powersectormodeling/BaseCasev513.html). The 2018 base case EGU projections include the Acid Rain Program, Clean Air Interstate Rule (CAIR), and Mercury and Air Toxics Standards. The base case does not include CSAPR, the proposed Clean PowerPlan orthe proposed 2015 ozone NAAQS, because ofthe time the projections were developed. 1

### November 27, 2013 (78 FR 70935), and January 14, 2014 (79 FR2437), respectively. The air quality modeling presented inthis transport information documentpre-dated, and therefore does not reflect, comments received from this public reviewprocess ofthe 2011 and 2018 emissions inventories. We note that the EPAplans to re-model 2011 and 2018 to provide updated projections of2018 design values and contributions, using revised inventories created inresponse to comments on this public review process and other emissions updates. The EPA usedthe Comprehensive Air Quality Model withExtensions (CAMx version 6.10) 12 

### for modeling the 2011 base year and 2018 base case emissions scenarios to identify sites withprojected nonattainment and maintenance problems in2018. As shown in Figure 1, the air quality model runs
were performed for a modeling domain that covers the 48 states inthe contiguous U.S. along with adjacentportions ofCanadaand Mexico

. The spatial resolution (i.e., grid size) for this modeling domain is 12 kmx 12 km. The 2011 and 2018 scenarios were also bothmodeled for the full year with 2011 meteorology.

12 Environ, April4, 2014 (http:// www.camx.com). 

### 2

### Figure 1. 

### Air quality modeling domain (area within the purple lines).



### B. Identification of Future NonattainmentandMaintenance ReceptorSites The ozone predictions from the 2011 and 2018 CAMx model runs were used to project ambient (i.e., measured) ozone design values to 2018 following the approach described inthe EPA's draft informationfor attainment demonstrationmodeling. 13 

### We selected 2011 as the base year to reflect the mostrecentNEI, and we selected 2018 to coincide withthe attainment date for moderate areas underthe 2008 ozone NAAQS. The draft modeling informationrecommends using 5-yearweighted average

13 The December 3, 2014, draft ozone, fine particulate matter andregional haze SIP modeling guidance is available at http://www.epa.gov/ttnlscramlguidance/guide/Draft

_03-P M-RH _Modeling_Guidance-2014.pdf



### 3ambient design values 14 centered onthe base year as the starting pointfor projecting design values to the future. Because 2011 is the base year ofemissions, we started withthe average ambient 8-hour ozone design values for the period 2009 through 2013 (i.e., the average ofdesign values for 2009-2011, 2010- 2012 and 2011-2013). The 5-year weighted average ambient design value at each site was projected to 2018 using model-predicted Relative Response Factors (RRFs) 15 which were calculated based on procedures described in the draft modeling information. The 2018 projected average ozone design values were evaluated to identify those sites with design values that exceedthe 2008 ozone NAAQS. 16 Those sites with 2018 average design values that exceedthe NAAQS are projectedto be nonattainment in 2018. We followed the CSAPR approach to identify sites withprojected maintenanceproblems in 2018 (76 FR48208). As part ofthe approach for identifying sites withprojected future maintenance problems, the highest (i.e., maximum) ambient design value from the 2011-centered 5-yearperiod (i.e., the maximum ofdesign values from 2009-2011, 2010-2012 and 2011-2013) was projectedto 2018 for each site using the site-specific RRFs. Monitoring sites with a 2018 maximum design value that exceeds the NAAQS are projected by the CSAPR approachto have a maintenanceproblemin2018. The base year ambient andprojected 2018 average and maximum design values at all monitoring sites are provided inthe AQMTSD. In 2018 there are 11 projected nonattainment sites and 18 projected maintenance sites in the East (See Table 1). These are the sites that are indicated from the EPA's preliminary modeling as warranting the evaluation ofcontributions from upwind states. T?eprojected 2018 nonattainment sites inthe East are located infour nonattainment areas: Baltimore, MD; New York City, NY (sites inbothNY and CT); Dallas, TX; and Houston, TX. Note that several ofthese nonattainment areas also contain additional sites that are projected as maintenance receptors. Also, there

are several projected maintenance-only areas inthe East: Holland, MI; Louisville, KY; Philadelphia, PA (including sites in bothNJ and PA); St. Louis, MO; and Sheboygan, WI (See Table 2).

14 The air quality design value for a site is the 3-year average annual fourth-highest daily maximum 8-hour average ozone concentration. 15 In brief, the RRF for a particular location is the ratio ofthe 2018 ozone model predictionto the 2011 ozone model prediction. The RRFs were calculated using model outputs for the May through September period. 16 In determining compliance with the NAAQS, ozone design values are truncated to integer values. For example, a design value of75.9 ppb is truncated to 75 ppb which is attainment. Inthis manner, design values at or above 76.0 ppb are considered nonattainment. 4

### Table 1. Ambient and 2018 projected average and maximum 8-hour ozone design values (DVs) at 2018 nonattainment receptors in the East (nonattainment receptors have a 2018 average design value**of~** 

### 76.0 ppb). Units are ppb.
2009- 2009- 2013Avg 2013 Max 2018 Avg 2018 Max State County Site ID DVs DVs DVs DVs Connecticut Fairfield 90013007 84.3 89.0 76

.7 81.0 Connecticut Fairfield 90019003 83.7 87.0 77.5 80.6 Maryland Harford 240251001 90.0 93.0 79.4 82.1 New York Suffolk 361030002 83.3 85.0 78

.2 79.8 Texas Brazoria 480391004 88.0 89

.0 80.5 81.4 Texas Denton 481210034 84.3 87.0 77

.0 79.5 Texas Harris 482010024 80.3 83.0 76.4 79.0 Texas Harris 482011034 81.0 82.0 76.6 77.6 Texas Harris 4820 11039 82.0 84.0 77.7 79.6 Texas Tarrant 484392003 87.3 90.0 79.7 82.2 Texas Tarrant 484393009 86.0 86.0 78.3 78.3



### Table 2. Ambient and 2018 projected average and maximum 8-hour ozone design values (DVs) at 2018 maintenance receptors in the East (maintenance receptors have a 2018 maximum design value**of~** 

### 76.0 ppb). Units are ppb.
2009- 2009- 2013 Avg 2013 Max 2018 Avg 2018 Max State County Site ID DVs DVs DVs DVs Connecticut Fairfield 90010017 80.3 83.0 74.1 76.6 Connecticut New Haven 90099002 85.7 89.0 75.8 78.8 Kentucky Jefferson 211110067 82.0 85.0 73

.7 76.4 Michigan Allegan 260050003 82.7 86

.0 74

.5 77.5 Missouri Saint Charles 291831002 82.3 86.0 74

. 1 77.4 NewJersey Camden 340071001 82.7 87.0 72.3 76.0 NewJersey Gloucester 340150002 84.3 87.0 74.0 76.3 NewYork Richmond 360850067 81.3 83.0 74.6 76.2 Pennsylvania Philadelphia 421010024 83.3 87.0 74.7 78.0 Texas Collin 480850005 82.7 84.0 75

.0 76.2 Texas Dallas 481130069 79.7 84.0 73.7 77.7 Texas Dallas 481130075 82.0 83.0 75.2 76.1 Texas Denton 481211032 82.7 84.0 75.1 76.3 52009- 2009- 2013 Avg 2013 Max 2018 Avg 2018 Max State County Site ID DVs DVs DVs DVs Texas Harris 482010029 83.0 84.0 75.4 76.3 Texas Harris 482010055 81.3 83.0 75.0 76.6 Texas Tarrant 484390075 82.0 83.0 75.5 76.4 Texas Tarrant 484393011 80.7 83.0 74.2 76.3 Wisconsin Sheboygan 551170006 84.3 87.0 75.4 77.8

C. Quantification of Interstate Ozone Contributions 

### The EPA performed nationwide, 17 

### state-level ozone source apportionment modeling using the CAMx Ozone Source Apportionment Technology/ Anthropogenic Precursor CulpabilityAnalysis (OSAT/APCA) technique 18 

### to quantify the contribution of2018 base case nitrogen oxides (NOx) and volatile organic compound (VOC) emissions from all sources in each state to projected 2018 ozone concentrations at air quality monitoring sites. Inthe source apportionment model run, we tracked the

ozone formed from each ofthe following contribution categories (i.e., "tags"):

• States- anthropogenic NOx and VOC emissions from each state tracked individually (emissions from all anthropogenic sectors in a given state were combined),

• Biogenics

- biogenic NOx and VOC emissions domainwide (i.e., not by state),

• Boundary Concentrations

- concentrationstransported into the nationwide modeling domain,

• Tribes -the aggregate ofemissions from those tribal lands for which we have point source inventory data inthe 2011 NEI (i.e., we did notmodel the contributions from individual tribes), and

• Other

- combined emissions from wild and prescribed fires, offshore emissions from marine vessels, offshore drilling platforms and anthropogenic emissions from the portions ofCanada and Mexico withinthe modeling domain.

17 As shown in Figure I, the EPA's nationwide modeling includes the 48 contiguous states. 18 As part ofthis technique, ozone formed from reactions between biogenic VOC andNOx with anthropogenic NOx and VOC are assigned to the anthropogenic emissions. 

### 6

### The CAMx OSAT/APCA model run was performed for the period May 1through September 30 using the projected 2018 base case emissions and 2011 meteorology for this time period. The hourly contributions 19 

### from eachtag wereprocessedto obtainthe 8-hour average contributions corresponding to the time period ofthe 8-hour daily maximum concentration on each day in the 2018 model simulation. This step was performed for those model grid cells containingmonitoring sites in order to obtain 8-hour average contributions for each day at the location ofeach site. The model-predicted contributions were then applied in a relative sense to quantify the contributions to the 2018 average design value at each site. First, the daily 8-hour contributions were averaged across the subset ofdays with 2018 model predictions exceeding the 2008 ozoneNAAQS (i.e., 8-hr daily**maximum~** 

### 76 ppb). For those sites with fewer than 5 predicted exceedance days in 2018, we averaged the contributions for the top five concentrations days. 2

# ° For each site, the multi-day average contribution from each tag was normalized by the sum ofthe contribution from all tags, combined. The resulting fractional contributions at each site were then applied to the 2018 average design value to quantify (i.e., "apportion") the design value into contributions from each tag. This process was performed for each monitoring site with a projected 2018 design value. Additional details onthe source apportionment modeling and the calculation ofcontributions can be found inthe AQMTSD. The resulting 2018 contributions from each tag to eachmonitoring site are provided inthe AQMTSD. The largest contributions from each state to 2018 downwind nonattainment receptors and to downwind maintenance receptors are provided in Table 3.

19 Contributions from anthropogenic emissions under "NOx-limited" and "VOC-limited" chemical regimes were combined to obtainthe net contribution from NOx and VOC anthropogenic emissions in each state. 20 Ifa site did nothave at least 5 days with a modeled 2018 8-hour daily maximum concentration2: 60 ppb, then contributions were not calculated at the monitor.


### 7

### Table 3. Largest ozone contributions from each state to downwind 2018 projected nonattainment and to 2018 projected maintenance receptors. Units are ppb. Largest Contributionto Largest Contribution to a 2018 Nonattainment a 20 18 Maintenance

Site in Downwind Site in Downwind Upwind State States States Alabama 1.06 1.39 Arizona 1.47a 0.44 Arkansas 1.25 2.19 California 0.23 1.16a Colorado 0.35 0.33 Connecticut 0.41 0.08 Delaware 0.63 2.46 District of Columbia 0

.69 0.29 Florida 0.87 1.05 Georgia 0.71 0.73 Idaho 0.09 0.22 Illinois 0.87 22.29 Indiana 1.93 11.41 Iowa 0.62 0.89 Kansas 0.70 1.15 Kentucky 1.94 2.40 Louisiana 3.38 4.37 Maine 0.01 0.00 Maryland 2.59 6.96 Massachusetts 0.21 0.12 Michigan 1.48 3.63 Minnesota 0.43 0.34 Mississippi 0.83 1.52 Missouri 1.53 4.12 Montana 0.14 0.17 Nebraska 0.36 0.56 Nevada 0.70 0.44 New Hampshire 0.03 0.02 New Jersey 9.21 9.95 New Mexico 0.26 0.20 NewYork 16.05 16.14 North Carolina 0.57 0.55 North Dakota 0.13 0.19 Ohio 4.06 4.41 Oklahoma 1.50 2.59 Oregon 0.69 0.73 Pennsylvania 9.85 18.76 Rhode Island 0.04 0.03 

### 8Largest Contribution to Largest Contribution to a 2018 Nonattainment a 2018 Maintenance

Site in Downwind Site in Downwind Upwind State States States South Carolina 0.36 0.35 South Dakota 0.09 0.12 Tennessee 0.69 0.99 Texas 0.92 2.74 Utah 0.29 1.43a Vermont 0.02 0.02 Virginia 4.42 3.27 Washington 0.21 0.13 WestVirginia 2.79 2.88 Wisconsin 0.34 2.49 Wyoming 0.37 1.29a
a These four western states (i.e., AZ, CA, UT, and WY) contribute above the 1percentthreshold to projected 2018 nonattainment ormaintenance sites in the West, as identified in the AQMTSD. 

### Table 4 indicates the projected state "linkages"to downwind 2018 nonattainmentreceptors inthe EasternU.S. 21 

### identifiedinthe air quality modeling using a threshold of 1percent ofthe 2008 ozone NAAQS (0.76 ppb), consistent with CSAPR. Table 5provides the same information for states that contribute at or above the 1percentthresholdto identified 2018 maintenance receptors inthe Eastern U.S. (States inthe EasternU.S. that are not listed inthese tables contribute below 1percent at all receptors).

21 Forthe purposes ofthis information document, we include the 37 states and the District ofColumbia in the region from Texas northward to North Dakota and eastwardto the East Coast as comprisingthe Eastern U.S. The Western U.S. refers to the 11 states in the contiguous U.S. west ofthose states (AZ, CA, CO, ID, MT, NM, NV, OR, UT, WA and WY). 

### 9

### Table 4. Ozone contributions at or above a 1 percent threshold from upwind states to 2018 nonattainment receptors in the Eastern 

### U.S. Units are ppb.
2018 Nonattainment Upwind States- Part 1 (AL through MS) Receptors County Site ID AL AR FL IL IN KY LA MD MI MS Fairfield, CT 90013007 2.11 0.93 Fairfield, CT 90019003 2.60 Harford, MD 240251001 1.93 1.95 0.86 Suffolk, NY 361030002 0.79 1.02 1.50 1.49 Brazoria, TX 480391004 1.00 0.88 3.25 0.81 Denton, TX 481210034 1.06 0.95 3.13 Harris, TX 482010024 0.87 2.24 Harris, TX 482011034 1.06 0.81 3.39 Harris, TX 482011039 1.25 2.93 0.84 Tarrant, TX 484392003 0.82 0.97 2.94 Tarrant, TX 484393009 1.19 2.29
Number ofLinkages=> 2 6 1 3 2 1 7 3 3 2

2018 Nonattainment Upwind States- Part2 (MO through WV) Receptors County Site ID MO NJ NY OH OK PA TX VA 

## wv Fairfield, CT 90013007 6.72 15.58 1.92 9.86 1.92 0.97 Fairfield, CT 90019003 8.17 16.06 1.50 9.30 2.17 0.89 Harford, MD 240251001 4.07 6.93 0.92 4.43 2.80 Suffolk, NY 361030002 9.21 2.52 9.79 0.80 1.72 0.99 Brazoria, TX 480391004 1.20 0.77 Denton, TX 481210034 1.12 Harris, TX 482010024 Harris, TX 482011034 1.53 1.51 Harris, TX 482011039 1.06 0.99 Tarrant, TX 484392003 1.22 Tarrant, TX 484393009 1.25
Number ofLinkages => 3 3 2 4 6 4 2 4 4



### 10

### Table 5. Ozone contributions at or above a 1 percent threshold from upwind states to 2018 maintenance receptors in the Eastern U.S. Units are ppb.
2018 Maintenance Receptors Upwind States- Part 1 (AL through LA) County Site ID AL AR DE FL IL IN lA KS KY LA Fairfield, CT 90010017 0.79 1.04 New Haven, CT 90099002 0.81 Jefferson, KY 211110067 1.09 11.42 Allegan, MI 260050003 2.19 22.30 8

. 17 0.89 1.15 Saint Charles, MO 291831002 0.87 1.53 7.07 0.78 Camden, NJ 340071001 1.85 1.33 1.66 0

.87 Gloucester, NJ 340150002 2.47 0.86 1.01 1.22 Richmond, NY 360850067 1.14 0.90 1.21 Philadelphia, PA 421010024 1.36 0.78 2.01 2.41 Collin, TX 480850005 1.06 1.91 Dallas, TX 481130069 1.07 1.55 Dallas, TX 481130075 1.13 1.55 Denton, TX 481211032 1.40 3.05 Harris, TX 482010029 0.77 1.05 4.32 Harris, TX 482010055 1.40 0.82 4.37 Tarrant, TX 484390075 0.94 1.03 2.33 Tarrant, TX 484393011 1.87 0.99 2.55 Shebovgan, WI 551170006 15.87 7.92 0.88 1.12
Number ofLinkages => 3 9 4 1 8 9 1 4 4 10

2018 Maintenance Receptors Upwind States -Part2 (MD through TN) County Site ID MD MI MS MO NJ NY OH OK PA TN Fairfield, CT 90010017 2.01 7.64 15.49 1.93 9.28 New Haven, CT 90099002 1.74 5.58 16.15 1.86 8.70 Jefferson, KY 211110067 1.23 3.93 Allegan, MI 260050003 4.13 1.70 Saint Charles, MO 291831002 0.89 0.77 Camden, NJ 340071001 1.58 0.95 1.54 4.42 18.76 Gloucester, NJ 340150002 6.97 1.03 1.34 3

.71 16.20 Richmond, NY 360850067 3.59 9.95 2.10 16.19 Philadelphia, PA 421010024 5.14 1.38 3.84 1.00 Collin, TX 480850005 0.91 Dallas, TX 481130069 1.06 Dallas, TX 481130075 1.07 112018 Maintenance Receptors Upwind States -Part2 (MD through TN) County Site ID MD MI MS MO NJ NY OH OK PA TN Denton, TX 481211032 1.22 Harris, TX 482010029 0.79 Harris, TX 482010055 1.52 0.95 Tarrant, TX 484390075 2.59 Tarrant, TX 484393011 0.81 2.55 Sheboygan, WI 551170006 3.64 1.81 1.64
Number ofLinkages=> 5 4 2 5 4 4 7 9 5 2

2018 Maintenance Receptors Upwind States- Part 3 TXthrough WI County Site ID TX VA 

### wv WI Fairfield, CT 90010017 1.88 0.87 NewHaven, CT 90099002 1.39 0.83 Jefferson, KY 211110067 Allegan, MI 260050003 2.75 2.49 Saint Charles, MO 291831002 2.38 Camden, NJ 340071001 1.45 1.17 Gloucester, NJ 340150002 0.97 2.95 2.23 Richmond, NY 360850067 3.28 2.03 Philadelphia, PA 421010024 1.01 2.39 2.88 Collin, TX 480850005 Dallas, TX 481130069 Dallas, TX 481130075 Denton, TX 481211032 Harris, TX 482010029 Harris, TX 482010055 Tarrant, TX 484390075 Tarrant, TX 484393011 Shebovgan, WI 551170006 2.26
Number ofLinkages=> 6 5 6 1

12