Cincinnati, Ohio-Kentucky-Indiana

Area Designations for the 

2008 Ozone National Ambient Air Quality Standards

The table below identifies the areas in Ohio, Kentucky, and Indiana that EPA is designating as 

“nonattainment” for the 2008 8-hour ozone National Ambient Air Quality Standard (NAAQS)1

as part of the Cincinnati, Ohio-Kentucky-Indiana (OH-KY-IN) multi-state nonattainment area. 

In accordance with section 107(d) of the Clean Air Act (CAA), EPA must designate an area 

(county or part of a county) as “nonattainment” if it is violating the 2008 ozone NAAQS or if it 

is contributing to a violation of the 2008 ozone NAAQS in a nearby area. The technical analyses 

supporting the boundaries for the individual state nonattainment areas are provided below.

Table 1. Areas in Ohio, Kentucky, and Indiana Included in the Cincinnati, OH-KY-IN 

Ozone Nonattainment Area

State State Recommended 

Nonattainment Counties

EPA’s Nonattainment 

Counties

Ohio Butler

Clermont

Clinton

Hamilton

Warren

Butler

Clermont

Clinton

Hamilton

Warren

Kentucky None Boone (partial)

Campbell (partial)

Kenton (partial)

Indiana None Dearborn (partial)

EPA is designating as “unclassifiable/attainment” for the 2008 8-hour ozone NAAQS: (1) the 

remaining counties in Ohio that are not included in the table above or in the Cleveland-AkronLorain, OH or Columbus, OH nonattainment areas (see the separate Technical Support 

Document for Ohio that covers the Cleveland-Akron-Lorain, OH and Columbus, OH ozone 

nonattainment areas); (2) the remaining counties and partial counties in Kentucky that are not 

included in the table above; and, (2) the remaining counties and partial counties in Indiana that 

are not included in the table above or that EPA is considering for inclusion as part of the 

Chicago-Naperville, Illinois-Indiana-Wisconsin (IL-IN-WI) ozone nonattainment area: EPA will 

issue a separate action no later than May 31, 2012 addressing all areas it is considering for 

inclusion as part of the Chicago-Naperville, IL-IN-WI ozone nonattainment area).

The analysis below provides the basis for the Cincinnati, OH-KY-IN nonattainment area 

boundary. It relies on our analysis of whether and which monitors are recording violations of the 

2008 ozone NAAQS, based on certified air quality monitoring data from 2008-2010 and on an 

evaluation of whether nearby areas are contributing to such violations. EPA has evaluated 

 

1 The primary 8-hour ozone standard, set to protect human health, was revised on March 27, 2008 (73 FR 16436) 

from 0.08 parts per million (ppm) to 0075 ppm. The secondary ozone standard, set to protect human welfare and the 

environment, was revised to be consistent with the primary ozone standard.
2

contributions from nearby areas based on a weight-of-evidence analysis considering the factors 

identified below. EPA issued guidance on December 4, 2008 that identified these factors as ones 

EPA would consider in determining nonattainment area boundaries, and recommended that states 

consider these factors in making their designation recommendations to EPA.2

1. Air quality data (including the ozone design value calculated for each Federal Reference 

Method or Federal Equivalent Method (FEM) monitor in the area);

2. Emissions and emissions-related data (including location of sources, population, amount 

of emissions and emission controls, and growth patterns);

3. Meteorology (weather/transport patterns);

4. Geography and topography (mountain ranges and other basin boundaries affecting ozone 

levels and ozone precursor transport); and,

5. Jurisdictional boundaries (e.g. counties, air districts, existing ozone nonattainment areas, 

Indian country, Metropolitan Planning Organization (MPOs) and their covered area).

Ground-level ozone is generally not emitted directly into the air, but is created by chemical 

reactions involving Nitrogen Oxides (NOx) and Volatile Organic Compounds (VOC) in the 

presence of sunlight.3 Because NOx and VOC emissions from a broad range of sources over a 

wide area typically contribute to violations of the ozone standards, EPA believes it is important 

to consider whether there are contributing emissions from a broad geographic area. Accordingly, 

EPA chose to examine the 5 factors with respect to the larger of the Combined Statistical Area 

(CSA) or Core Based Statistical Area (CBSA) associated with the violating monitor(s).4

 All data 

and information used by EPA in this evaluation are the latest available to.

In EPA’s designations guidance for the 2008 ozone NAAQS, EPA recommended examining 

CSA/CBSAs because certain factors used to establish CSAs and CBSAs are similar to the factors 

EPA is using in this technical analysis to determine if a nearby area is contributing to a violation 

of the 2008 ozone NAAQS. Congress required a similar approach in 1990 for areas classified as 

serious and above for the 1-hour ozone standard and EPA used the same approach in the 

designation process for the 1997 ozone NAAQS. Where a violating monitor is not located in a 

CSA or CBSA, EPA’s September 4, 2008 guidance recommends using the boundary of the 

county containing the violating monitor as the starting point for considering the nonattainment 

area’s boundary.

 

2 The December 4, 2008 guidance memorandum, “Area Designations for the 2008 Revised Ozone National 

Ambient Air Quality Standards,” refers to 9 factors. In this technical support document, we have grouped the 

emissions-related factors together under the heading of “Emissions-Related Data,” which results in 5 categories of 

factors.

3 Peak ozone concentrations generally occur downwind of source areas on relatively sunny days with high 

temperatures and relatively low wind speeds.

4 Lists of CBSAs and CSAs and their geographic components are provided at 

www.census.gov/population/www/metroareas/metrodef.html. The lists are periodically updated by the Office of 

Management and Budget. EPA used the most recent update, based on 2008 population estimates, issued on 

December 1, 2009 (OMB Bulletin No. 10-02).
3

Technical Analysis for Cincinnati, OH-KY-IN

Figure 1 is a map of the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA, which includes 

the Cincinnati, OH-KY-IN ozone nonattainment area (indicated in blue colors in the map). The 

map provides other relevant information, including the locations and ozone design values5 of 

ozone air quality monitors, county and other jurisdictional boundaries, existing maintenance area 

boundary for the 1997 8-hour ozone NAAQS, and major transportation arteries.

Figure 1. Cincinnati, OH-KY-IN Ozone Nonattainment Area within the CincinnatiMiddletown-Wilmington, OH-KY-IN CSA

For purposes of the 1997 ozone NAAQS, as noted in Figure 1, portions of this CSA were 

designated nonattainment and subsequently redesignated to attainment (maintenance). The 

boundary for the nonattainment area for the 1997 ozone NAAQS included the entire counties of 

Butler, Clermont, Clinton, Hamilton, and Warren in Ohio and Boone, Campbell, and Kenton in 

Kentucky and part of Dearborn County (Lawrenceburg Township) in Indiana.

 

5 The average of the annual fourth-highest daily maximum 8-hour ozone concentrations for a three-year period, in 

this case 2008-2010.
4

In March 2009, Ohio recommended that Butler, Clermont, Clinton, Hamilton, and Warren 

Counties be designated as “nonattainment” for the 2008 8-hour ozone NAAQS based on ozone

air quality data from 2006-2008. In March 2009, Kentucky recommended that Kenton County 

by designated as “nonattainment” for the 2008 8-hour ozone based on ozone air quality data 

from 2006-2008. However, in October 2011, Kentucky submitted an update to its 2009 

recommendation and revised its recommendation to “attainment” designations for all counties in 

the Commonwealth of Kentucky. Finally, in March 2009, Indiana recommended that all 

counties in Indiana, including those in the Cincinnati-Middletown-Wilmington, OH-KY-IN

CSA, be designated as “attainment” for the 2008 8-hour ozone NAAQS based on 2006-2008 

ozone air quality data. Letter from Chris Korlecki, Director, Ohio Environmental Protection 

Agency, to Lynn Buhl, Regional Administrator, U.S. Environmental Protection Agency, Region 

5 (March 9, 2009). Letter from Leonard K. Peters, Secretary, Kentucky Energy and 

Environmental Cabinet, to A. Stanley Meiburg, Acting Regional Administrator, U.S. 

Environmental Protection Agency, Region 4 (March 12, 2009). Letter from Leonard K. Peters, 

Secretary, Kentucky Energy and Environmental Cabinet to Gwendolyn Keyes Fleming, Regional 

Administrator, U.S. Environmental Protection Agency, Region 4 (October 13, 2011). Letter 

from Thomas W. Easterly, Commissioner, Indiana Department of Environmental Management, 

to Bharat Mathur, Acting Regional Administrator, U.S. Environmental Protection Agency, 

Region 5 (March 11, 2009). All ozone data discussed in these State submittals and reviewed in 

this Technical Support Document are from FEM monitors sited and operated in accordance with 

40 CFR part 58.

On December 9, 2011, EPA initiated the 120 day consultation process by notifying the 

Commonwealth of Kentucky, and the States of Indiana and Ohio, that, based on EPA’s technical

analysis of the 16-county Cincinnati-Middletown-Wilmington, OH-KY-IN CSA, EPA intended 

to designate one partial county in Indiana, three whole counties in Kentucky, and five whole 

counties in Ohio (identified in Table 2 below) as “nonattainment” for the 2008 8-hour ozone 

NAAQS as part of the Cincinnati, OH-KY-IN nonattainment area. In the December 2011 letters 

to the Commonwealth of Kentucky and the States of Indiana and Ohio, EPA also requested that, 

if the Commonwealth of Kentucky and the States of Indiana and Ohio wished to provide 

comments on EPA’s intended designation or to use early certified data for designation, they 

should provide comments or early certify by February 29, 2012..
5

Table 2. State’s Recommended and EPA’s Intended Nonattainment Counties for the 

Cincinnati, OH-KY-IN Area in the December 9, 2011 Letters

State State Recommended 

Nonattainment Counties

EPA Intended

Nonattainment Counties

Indiana None Dearborn (partial)

Kentucky None Boone *

Campbell

Kenton

Ohio Butler

Clermont

Clinton

Hamilton

Warren

Butler

Clermont

Clinton

Hamilton

Warren

* Bold italics county names represent counties that were modified in the final nonattainment area 

boundary determination for the Cincinnati, OH-KY-IN nonattainment area.

On February 21, 2012, Kentucky submitted additional information in support of the 

Commonwealth’s recommendation to designate Boone, Campbell, and Kenton Counties as 

attainment for the 2008 8-hour ozone NAAQS. In summary, Kentucky, using the same 

emissions information that EPA used for the December 9, 2011, technical support document, 

noted the difference in emissions and sources between the Kentucky portion of the intended 

ozone nonattainment area and the Ohio portion of the intended ozone nonattainment area. 

Kentucky noted that the emissions from Boone, Campbell, and Kenton Counties only contributed 

a minimal amount to violations of the 2008 8-hour ozone NAAQS at the violating monitors. The 

States of Indiana and Ohio did not submit additional technical information for EPA to consider 

in response to EPA’s December 9, 2011, letters.

EPA originally started with the CSA or CBSA areas for evaluating what areas violate and 

contribute to violations of the 2008 8-hour ozone NAAQS, and, for final determinations refined 

its evaluations based on additional technical information provided by the states and tribes. After 

considering the recommendations from Indiana, Kentucky, and Ohio, the additional technical 

information provided by Kentucky, and based on EPA’s reevaluation of the five factors as 

described below, EPA is designating a portion of Dearborn County in Indiana, portions of 

Boone, Campbell, an Kenton Counties in Kentucky, and the whole of Butler, Clermont, Clinton, 

Hamilton, and Warren Counties in Ohio as “nonattainment” for the 2008 8-hour ozone NAAQS 

as the Cincinnati, OH-KY-IN nonattainment area. 
6

Factor Assessment

Factor 1: Air Quality Data

For this factor, EPA considered 8-hour ozone design values, in parts per million (ppm), for air 

quality monitors in counties in the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA based 

on data for the 2008-2010 period (i.e., 2010 ozone design values), which are the most recent 

years with quality assured, state-certified air quality data. A monitor’s design value is the metric 

or statistic that indicates whether that monitor attains a specified air quality standard. The 2008 

ozone NAAQS are met at a monitor when the annual fourth-highest daily maximum 8-hour 

average concentration, averaged over the most recent three years is 0.075 ppm or less. A design 

value is valid only if minimum data completeness criteria are met. See 40 CFR part 50 

Appendix P. Where several monitors are located in a county (or a designated nonattainment area 

or maintenance area), the design value for the county or area is determined by the monitor with 

the highest individual design value.

Note: Monitors that are eligible for providing design value data generally include State and 

Local Air Monitoring Stations (SLAMS) that are sited in accordance with 40 CFR Part 58, 

Appendix D (Section 4.1) and operating with a Federal Reference Method (FRM) or Federal 

Equivalent Method (FEM) monitor that meets the requirements of 40 CFR part 58, appendix A. 

All data from a special purpose monitor (SPM) using an FRM or FEM which has operated for 

more than 24 months is eligible for comparison to the NAAQS unless the monitoring agency 

demonstrates that the data came from a particular period during which the requirements of 

appendix A (quality assurance requirements) or appendix E (probe and monitoring path citing 

criteria) were not met.

The 2008-2010 ozone design values for monitors and counties in the Cincinnati-MiddletownWilmington, OH-KY-IN CSA are shown in Table 3.

Table 3. Ozone Air Quality Data for the Cincinnati-Middletown-Wilmington, OH-KY-IN 

CSA

State/County Site Number 2008-2010 8-hour Ozone Design 

Values (ppm)

Ohio:

Butler 390170018 0.078†

Butler 390170004 0.073

Clermont 390250022 0.071

Clinton 390271002 0.074

Hamilton 390610040 0.076†

Hamilton 390610010 0.073

Hamilton 390610006 0.079†

Warren 391650007 0.078†

Kentucky:

Boone 210150003 0.065

Campbell 210373002 0.072

† Monitored violation of the 2008 ozone NAAQS.
7

Butler, Hamilton, and Warren Counties in Ohio show violations of the 2008 ozone NAAQS. 

Therefore, these counties are included in the Cincinnati, OH-KY-IN nonattainment area. A 

county (or partial county) must also be designated nonattainment if it contributes to a violation in 

a nearby area. Each county without a violating monitor that is located near a county with a 

violating monitor has been evaluated based on the weight-of-evidence of the five factors to 

determine whether it contributes to the nearby violation.

Please note that the State of Ohio, in its March 9, 2009 area designation recommendations and 

accompanying technical support documentation, based its recommendations on 2006-2008 ozone 

data. Since these data no longer cover the most recent 3-year period with quality-assured, statecertified data and have been supplanted by the more current 2008-2010 ozone data, EPA is not 

reviewing the older ozone data relied on by the State of Ohio for its 2009 recommendation.

Factor 2: Emissions and Emissions-Related Data

EPA evaluated emissions for ozone precursors (VOC and NOx) and other emissions-related data 

that provide information on area contributions to ozone standard violations.

Emissions Data

EPA evaluated county-level emission data for NOx and VOC derived from the 2008 National 

Emissions Inventory (NEI), version 1.5. This is the most recently available NEI. (See 

http://www.epa.gov/ttn/chief/net/2008inventory.html). Significant emissions levels in a nearby 

area indicate the potential for the area to contribute to observed violations. EPA also considered 

any additional information received on changes to emissions levels that are not reflected in 

recent inventories. 

Table 4 shows the 2008 emissions of VOC and NOx (tons per year (tpy)) for all counties in the 

Cincinnati-Middletown-Wilmington, OH-KY-IN CSA. 

Table 4. Total 2008 VOC and NOx Emissions (tons/year) in the Cincinnati-MiddletownWilmington, OH-KY-IN CSA

State/County State Recommended 

Nonattainment?

VOC Emissions

(tpy)

NOx Emissions

(tpy)

Indiana:

Dearborn No 3,572 11,637

Franklin No 1,097 862

Ohio No 210 259

Kentucky:

Boone No 4,332 8,848

Bracken No 361 760

Campbell No 2,260 2,697

Gallatin No 671 1,634
8

Grant No 1,148 1,623

Kenton No 3,901 4,095

Pendleton No 608 1,394

Ohio:

Brown No 1,720 1,430

Butler Yes 10,813 12,600

Clermont Yes 5,809 28,461

Clinton Yes 2,618 2,941

Hamilton Yes 26,816 38,664

Warren Yes 5,618 6,027

CSA Total 71,554 123,933

Emissions Observations for each State

Indiana:

From the emissions in Table 3, it can be seen that, for Indiana, relatively high 2008 VOC and 

NOx emissions in the vicinity of the violating counties originate in Dearborn County. Emissions 

from this county in 2008 account for 5.0 percent of the VOC emissions and 9.4 percent of the 

NOx emissions for the entire Cincinnati-Middletown-Wilmington, OH-KY-IN CSA. The 

majority of these emissions come from the American Electric Power (AEP) - Tanners Creek 

Generating Station located in Lawrenceburg Township, adjacent to the Ohio portion of the final 

nonattainment area.

The VOC and NOx emissions from Franklin and Ohio Counties in Indiana are considerably 

smaller than those originating in the higher emitting counties elsewhere in the CincinnatiMiddletown-Wilmington, OH-KY-IN CSA. This supports the exclusion of these counties from 

the ozone nonattainment area for the 2008 8-hour ozone NAAQS.

Kentucky:

Based on the 2008 NEI, 62 percent of Boone County’s NOx emissions are from point sources, 

and 21 percent from mobile sources. Less than 5 percent of Campbell County’s NOx emissions 

are from point sources and 57 percent of Campbell County’s NOx emissions are from mobile 

sources. Kenton County also has less than 5 percent of its NOx emission from point sources, but 

63 percent of Kenton County’s NOx emissions are from mobile sources. Boone County has 29 

percent of its VOC emission coming from area sources and 23 percent of its VOC emissions 

from mobile sources. Campbell County has 35 percent of its VOC emissions coming from area 

sources and 43 percent of VOC emissions from mobile sources. Kenton County has 38 percent 

of its VOC emission coming from area sources and 41 percent of its VOC emissions from mobile 

sources. The total VOC and NOx emissions in each of Boone, Campbell, and Kenton Counties 

are considered to be significant contributors to the high ozone concentrations in the Cincinnati, 

OH-KY-IN nonattainment area for the 2008 8-hour ozone NAAQS.

The VOC and NOx emissions from Bracken, Gallatin, Grant, and Pendleton Counties, Kentucky 

are considerably less than those originating in the higher emitting counties elsewhere in the 
9

Cincinnati-Middletown-Wilmington, OH-KY-IN CSA. This supports the exclusion of these 

counties from the ozone nonattainment area for the 2008 8-hour ozone NAAQS.

Ohio:

From the Ohio emissions data in Table 3, it can be seen that comparatively high 2008 VOC and 

NOx emissions in the vicinity of the violating counties originate in the following counties: 

Butler, Clermont, Hamilton, and Warren. Emissions from these counties in 2008 account for 

68.6 percent of the VOC emissions and 69.2 percent of the NOx emissions in the entire 

Cincinnati-Middletown-Wilmington, OH-KY-IN CSA. 

The VOC and NOx emissions in Clinton County are similar to those in Campbell County, 

Kentucky, which EPA has decided to include in the ozone nonattainment area. Therefore, this 

favors also including Clinton County, Ohio in the ozone nonattainment area.

The VOC and NOx emissions in Brown County, Ohio are significantly lower than those of other 

counties EPA is including in the ozone nonattainment area. Therefore, this supports the 

exclusion of Brown County from the ozone nonattainment area. As noted elsewhere in this 

Technical Support Document, this is also supported by the State of Ohio’s recommendation that 

this county be excluded from the ozone nonattainment area.

Population, Population Density, and Degree of Urbanization

EPA evaluated the population and vehicle use characteristics and trends of the Area as indicators 

of the probable location and magnitude of non-point source emissions. These include ozonecreating emissions from on-road and off-road vehicles and engines, consumer products, 

residential fuel combustion, and consumer services. Areas of dense population or commercial 

development are an indicator of area source and mobile source NOx and VOC emissions that 

may contribute to violating ozone monitors. Figure 2 shows the population density for the 

Cincinnati-Middletown-Wilmington, OH-KY-IN CSA.
10

Figure 2. Population Density in the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA

Figure created using GIS data layers available on-line from ESRI. 

http://goto.arcgisonline.com/maps/Demographics/USA_Population_Density

Rapid population or vehicle miles traveled (VMT) growth (see below) in a county on the urban 

perimeter signifies increasing integration with the core urban area, and indicates that it is be 

appropriate to include the Area associated with the area source and mobile source emissions as 

part of the nonattainment area. Table 5 shows the population, population density, and population 

growth information for each county in the Cincinnati-Middletown-Wilmington, OH-KY-IN 

CSA. 

Table 5. Population and Population Growth in the Cincinnati-Middletown-Wilmington, 

OH-KY-IN CSA

State/County State 

Recommended 

Nonattainment

2010 

Population

2010 

Population 

Density

Change in 

Population 

(2000-2010)

Population 

Percent 

Change 
11

(1,000 per 

square mile)

(2000-2010)

Indiana:

Dearborn No 50,047 0.16 3,702 8

Franklin No 23,087 0.06 866 4

Ohio No 6,128 0.07 492 9

Kentucky:

Boone No 118,811 0.46 31,811 37

Bracken No 8,488 0.04 211 3

Campbell No 90,336 0.57 1,680 2

Gallatin No 8,589 0.08 705 9

Grant No 24,662 0.09 2,115 9

Kenton No 159,720 0.97 8,032 5

Pendleton No 14,877 0.05 389 3

Ohio:

Brown No 44,846 0.09 2,263 5

Butler Yes 368,130 0.78 34,447 10

Clermont Yes 197,363 0.43 18,733 10

Clinton Yes 42,040 0.10 1,378 3

Hamilton Yes 802,374 1.94 -41,916 -5

Warren Yes 212,693 0.52 52,006 32

Area-wide 2,172,191 0.45 116,914 6

*Counties that EPA is designating as nonattainment are shown in bold.

Sources: U.S. Census Bureau population estimates for 2010 as of August 4, 2011

(http://factfinder2.census.gov/faces/tableservices/jsf/pages/productview.xhtml?pid=DEC_10_PL

_GCTPL2.STO5&prodType=table)

Population Observations for each State

Indiana:

The populations of the Indiana counties in the Cincinnati-Middletown-Wilmington, OH-KY-IN 

CSA are smaller than those of the Ohio counties and larger Kentucky counties in this CSA, but 

Dearborn County has a moderate population implying moderate population-related VOC and 

NOx emissions. In addition, the population change percentage change from 2000 to 2010 in 

Dearborn County is greater than the population change percentage for the entire CincinnatiMiddletown-Wilmington, OH-KY-IN CSA, implying that the population-related emission 

contribution from this county may be increasing relative to those from other counties in the 

Cincinnati-Middletown-Wilmington, OH-KY-IN area. Ohio County, Indiana also has a greater 

population change percentage as well, but the lower population in this county (which is the 

lowest for any county in the CSA) indicates this change is less significant.
12

Kentucky:

For Kentucky, Boone, Campbell, and Kenton Counties have relatively high populations and 

population densities when compared to the rest of the CSA. Additionally, Boone, Campbell and 

Kenton Counties are highly developed in the northern portions of the counties near the Ohio 

border. Bracken, Gallatin, Grant and Pendleton are smaller when compared to the counties 

included in the nonattainment area. Boone County at 37 percent and Warren County at 32 

percent had the highest percentage of population growth for any of the counties included in the 

Cincinnati-Middletown-Wilmington, OH-KY-IN CSA. Other counties in this CSA did not have 

as large of a population percentage change with the growth rates ranging from a 2 to 10 percent 

increase.

Ohio:

For Ohio, the population data show that Butler, Clermont, Hamilton, and Warren Counties have 

comparatively large populations and population densities. This implies that the populationrelated VOC and NOx emissions in these counties are relatively high. In addition, the population 

change percentages in Butler, Clermont, and Warren Counties between 2000 and 2010 exceed 

the population change percentage for the entire Cincinnati-Middletown-Wilmington, OH-KY-IN 

area, implying that the population-related emission contributions from these counties are 

increasing compared to those from other counties in the Cincinnati-Middletown-Wilmington, 

OH-KY-IN area. Hamilton County, Ohio population decreased by 5 percent between 2000 and 

2010, but the population in this county remains relatively high compared to the populations of 

other counties in the CSA.

Traffic and Commuting Patterns

EPA evaluated the total VMT for each county in the Cincinnati-Middletown-Wilmington, OHKY-IN CSA. In combination with the population/population density data and the location of 

main transportation arteries (see above area map), this information helps identify the probable 

location of non-point source emissions. A county with high VMT is generally an integral part of 

an urban area and indicates the presence of relatively high motor vehicle emissions that may 

significantly contribute to ozone formation and transport that contributes to nonattainment in the 

urban area. Rapid population or VMT growth in a county on the urban perimeter signifies 

increasing integration with the core urban area, and suggests that this county should be included 

in the ozone nonattainment area, particularly if the VOC and/or NOx emissions in this county are 

a significant portion of the total emissions in the nonattainment area.

Table 6 shows the traffic levels, total 2008 VMT, in each county in the Cincinnati-MiddletownWilmington, OH-KY-IN CSA.
13

Table 6. Traffic Levels in the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA

State/County State 

Recommended 

Nonattainment

2008 VMT*

(million 

miles)

Indiana:

Dearborn No 904

Franklin No 316

Ohio No 63

Kentucky:

Boone No 1,095

Bracken No 89

Campbell No 1,005

Gallatin No 278

Grant No 432

Kenton No 1,669

Pendleton No 182

Ohio:

Brown No 413

Butler Yes 2,469

Clermont Yes 1,464

Clinton Yes 655

Hamilton Yes 7,391

Warren Yes 1,640

Area-wide 20,063 * MOBILE model VMT are those input into the NEI version 1.5 use to compute the mobile 

source portion of the NEI emissions summarized above in Table 4.

VMT Observations by State

Ohio:

For Ohio, the VMT data show that VMT levels in Hamilton, Butler, Warren, and Clermont 

Counties rank first, second, fourth, and fifth, respectively, for the total VMT for the CincinnatiMiddletown-Wilmington, OH-KY-IN CSA.

Indiana:

For Indiana, the data show that the VMT level in Dearborn County ranks eighth for the total 

VMT for the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA.
14

Kentucky:

The VMT data show that VMT levels in Kenton, Boone, and Campbell Counties rank third, 

sixth, and seventh, respectively, for the total VMT for the Cincinnati-Middletown-Wilmington, 

OH-KY-IN CSA.

The VMT for the remaining counties in the CSA are lower in ranking.

Additional Emissions-Related Data Discussed in Ohio’s March 9, 2009 Designation 

Recommendation Submittal

The State of Ohio, through the Ohio Environmental Protection Agency (OEPA), has provided a 

detailed discussion of the county-specific VOC and NOx emissions, populations, and traffic and 

commuting patterns for the Ohio counties in the Cincinnati-Middletown-Wilmington, OH-KYIN CSA. These data support our conclusions discussed above, but also allow us to further refine 

EPA’s analysis for Factor 2 for the Ohio portion of the CSA. This is particularly true for growth 

in county populations and traffic levels and the inter-county impact of commuter traffic.

With regard to emissions, Ohio shows that both VOC and NOx daily emissions in Brown County 

are considerably lower than many other counties in the Cincinnati-Middletown-Wilmington, 

OH-KY-IN CSA. This confirms our conclusion that Brown County emissions are relatively low 

and would not support inclusion of this county in the ozone nonattainment area.

Ohio has projected county-populations through 2030. These population projections show that 

populations in Clinton and Brown Counties will remain comparatively low through 2030. 

Whereas, the populations of Butler, Clermont, Hamilton, and Warren Counties are projected to 

significantly increase and remain relatively high through 2030.

Estimated daily VMT in Brown County are shown to be largely unchanged beginning in 2001 

through 2007, and daily VMT in Hamilton County are estimated to be similarly unchanged 

between 1990 and 2007. In contrast, daily VMT levels have shown significant growth trends in 

Butler, Clinton, Clermont, and Warren Counties between 1990 and 2007.

The State of Ohio notes that the vast majority of workers traveling out of county from Butler, 

Warren, and Clermont Counties commute to Hamilton County. This conclusion is supported by 

tabulated inter-county commuter numbers and percentages in Ohio’ March 9, 2009 submittal. It 

is also noted that approximately 15 percent of the Hamilton County workers commute outside of 

the county, with the majority traveling to Butler County, with significant numbers of commuters 

also traveling from Hamilton County to Warren and Clermont Counties. The commuter numbers 

for Brown County show a much smaller number commuters traveling to or from other counties 

in the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA.

Considering all of the information provided by the State of Ohio supports the conclusion that 

there is strong urban integration of Butler, Clermont, Hamilton, and Warren Counties. In 

contrast, Clinton and Brown Counties are not significantly integrated with the Cincinnati urban 

area. This favors the exclusion of Brown County from the Cincinnati-Middletown-Wilmington, 
15

OH-KY-IN ozone nonattainment area for the 2008 ozone NAAQS. Clinton County, however, 

cannot be excluded from the ozone nonattainment area due to jurisdictional boundary 

considerations, as discussed for Factor 5 below.

Factor 3: Meteorology (Weather/Transport Patterns)

For this factor, EPA analyzed 30-years of National Weather Service (NWS) wind speed and 

wind direction data collected at the Covington/Greater Cincinnati Airport (NWS Station 93814) 

to help determine transport patterns and source contributions. EPA assessed wind direction and 

speed for the 2008-2010 “ozone season” (March through October) in the CincinnatiMiddletown-Wilmington, OH-KY-IN CSA. These analyses were conducted to better understand 

the fate and transport of precursor emissions contributing to ozone formation. EPA’s analysis of 

the NWS data indicate predominate south-southwest and west-southwest component for the 

Cincinnati-Middletown-Wilmington, OH-KY-IN CSA. These wind directions are typical of 

wind directions on high ozone days in this area. 

Factor 4: Geography/Topography (Mountain Ranges or Other Air Basin Boundaries)

The geography/topography analysis evaluates the physical features of the land that might affect 

the air shed and, therefore, the distribution of ozone over the area.

While the Cincinnati-Middletown-Wilmington, OH-KY-IN CSA does not appear to have major 

geographical or topographical barriers significantly limiting air pollution transport within its air 

shed, EPA notes that geographically, the northern portions of Kenton and Campbell Counties in 

Kentucky area are in very close proximity (just across Ohio River) from the core of the 

downtown Cincinnati area.

Factor 5: Jurisdictional Boundaries

Once EPA identified the general area to be included in the nonattainment area, EPA considered 

existing jurisdictional boundaries for the purposes of providing a clearly defined legal boundary 

and to help identify the areas appropriate for carrying out the air quality planning and 

enforcement functions for nonattainment areas. Examples of jurisdictional boundaries include 

existing/prior nonattainment area boundaries for ozone or other urban-scale pollutants, county 

lines, air district boundaries, township boundaries, areas covered by MPOs, state lines, 

Reservation boundaries, and urban growth boundaries. Where existing jurisdictional boundaries 

were not adequate or appropriate to describe the nonattainment area, other clearly defined and 

permanent landmarks or geographic coordinates were considered.

The Cincinnati-Middletown-Wilmington, OH-KY-IN CSA has previously established 

nonattainment boundaries associated with the both the 1-hour ozone NAAQS and with the 1997 

8-hour ozone NAAQS. The Cincinnati nonattainment boundary for the 1-hour ozone NAAQS 

included Boone, Campbell and Kenton Counties in their entireties in Kentucky; Butler, 

Clermont, Hamilton and Warren Counties in their entireties in Ohio. Whereas the Cincinnati 

nonattainment boundary for the 1997 8-hour ozone NAAQS included Boone, Campbell and 

Kenton Counties in their entireties in Kentucky, Butler, Clermont, Clinton, Hamilton and Warren 
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Counties in their entireties in Ohio, and a portion of Dearborn County (Lawrenceburg Township)

in Indiana. Kentucky and Indiana have recommended a different boundary for the 2008 ozone 

NAAQS for their portion of this Area. Ohio recommended the same area as included in the 

nonattainment area for the 1997 8-hour ozone NAAQS. 

In review of the emissions from the Kentucky Counties that were found to contribute to the 

violations at monitors in Ohio, EPA determined that these emissions were primarily populationbased emissions such as mobile sources. Thus, EPA determined it was most appropriate to 

capture the urbanized area for the Kentucky Counties in the Cincinnati, OH-KY-IN 

nonattainment area. An Urbanized Area (UZA), as defined by the Census Bureau, consists of a 

central core and adjacent densely settled territory that together contain at least 50,000 people, 

generally with an overall population density of at least 1,000 people per square mile. EPA 

evaluated the 2000 Census UZA data for the Kentucky portion of the Cincinnati-MiddletownWilmington, OH-KY-IN CSA in order to help define partial boundaries for Boone, Kenton, and 

Campbell Counties. EPA overlaid the UZA areas with census tracts to determine the high 

population census tracts in Boone, Campbell, and Kenton Counties. (See Figure 3). All of the 

census tracts in Boone, Campbell, and Kenton Counties are included in the nonattainment area 

for the 2008 8-hour ozone NAAQS, excluding census tracks 706.01 and 706.04 in Boone 

County, 637.01 and 637.02 in Kenton County, and 520.01 and 520.02 in Campbell County.
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Figure 3. Cincinnati Urbanized Area and Census Tracts

Conclusion

Indiana:

For Indiana, Franklin and Ohio Counties have low emissions, low VMTs, and low populations. 

These counties are mostly rural with no major point source emissions and minimal amounts of 

nonpoint source and mobile emissions. The areas were not included in the Cincinnati ozone 

nonattainment area for the 1997 ozone NAAQS. EPA believes that Franklin and Ohio Counties 

contribute minimally, at most, to the ozone standard violations at the three monitors that are 

violating in the Cincinnati, OH-KY-IN area. EPA is not including these counties in the ozone 

nonattainment area.

Lawrenceburg Township in Dearborn County contains the AEP- Tanner’s Creek Generating 

Station that has high NOx and VOC emissions. Dearborn County also has the potential to have 

moderate mobile source and population related VOC and NOx emissions, with the highest 

population being located in Lawrenceburg Township. Lawrenceburg Township was included as 

part of the designated nonattainment area for the 1997 8-hour ozone NAAQS. Lawrence 
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Township contains the only major stationary source and accounts for the majority of the 

emissions for the area. The remainder of the county is fairly rural and is similar to Franklin and 

Ohio Counties in other emission aspects. Therefore, EPA is including Lawrenceburg Township 

in Dearborn County, Indiana as part of the Cincinnati, OH-KY-IN ozone nonattainment area for 

the 2008 8-hour ozone NAAQS and designating the remainder of the county as 

unclassifiable/attainment for this NAAQS.

Kentucky:

Based on the assessment of factors described above for Kentucky, EPA has concluded that 

portions of Boone, Campbell Counties must be included as part of the Cincinnati, OH-KY-IN 

nonattainment area because they are contributing to a violation in a nearby area. The total of 

mobile source and area source emissions comprise approximately 40 percent of the total mobile 

source and area source NOx emissions in the Cincinnati-Middletown-Wilmington, OH-KY-IN 

CSA. The total of mobile source and area source emissions comprise approximately 75 percent 

of the total mobile source and area source VOC emissions in the Cincinnati-MiddletownWilmington, OH-KY-IN CSA. Point sources comprise approximately 50 percent of the total 

NOx emissions and 10 percent of the total VOC emissions in the Cincinnati-MiddletownWilmington, OH-KY-IN CSA. As indicated in the factors above, Boone, Campbell, and Kenton 

Counties have sources of NOx and VOC emissions; rank among the highest VMT contributors 

for the Cincinnati, OH-KY-IN nonattainment area; have high population densities and high 

population growth in Boone County. The northern portions of these counties are in close 

proximity to and have easy access to the core of the Cincinnati, OH-KY-IN area. As such, EPA 

is designating portions of Boone, Campbell, and Kenton Counties as part of the Cincinnati, OHKY-IN nonattainment area. The partial county boundary for Boone, Campbell, and Kenton 

Counties includes all of the census tracks in these counties except the census tracks 706.01 and 

706.04 in Boone County, 637.01 and 637.02 in Kenton County, and 520.01 and 520.02 in 

Campbell County.

Ohio:

For Ohio, EPA is designating the five counties recommended by the State of Ohio for inclusion 

in the Cincinnati, OH-KY-IN nonattainment area for the 2008 ozone NAAQS. These five 

counties were also included in the ozone nonattainment area for the 1997 8-hour ozone NAAQS. 

Butler, Hamilton, and Warren Counties must be included in the Cincinnati, OH-KY-IN ozone 

nonattainment area based on violations of the 2008 ozone NAAQS in these counties. EPA also 

notes that these counties are among the highest in this nonattainment area in terms of emissions, 

VMTs, and populations. While Clermont and Clinton Counties have comparatively low 

emissions, populations, and VMTs, EPA notes that there are emission sources in these counties 

and our analysis of the meteorological information indicates that emissions from these counties 

can contribute to exceedances of the 2008 ozone NAAQS at the violating monitors on the days 

when the ozone standards are exceeded.