Tennessee

Unclassifiable Area Designations for the

2012 Primary Annual PM2.5 National Ambient Air Quality Standards

Technical Support Document

1.0 Summary 

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

designations for all areas of the country. In particular, the EPA must identify those areas that are 

violating a National Ambient Air Quality Standard (NAAQS) or contributing to a violation of the 

NAAQS in a nearby area. Additionally, through the designation process, the EPA identifies areas 

that are meeting the NAAQS and those areas without sufficient data for the Agency to make a 

determination. The EPA uses a designation category of "unclassifiable/attainment" for areas 

where air quality monitoring data indicate attainment of the NAAQS and for areas that do not 

have monitors but for which the EPA has reason to believe are likely to be in attainment and are 

not contributing to nearby violations. The EPA reserves the category of "unclassifiable" for areas 

where the EPA cannot determine based on available information whether the area is meeting or 

not meeting the NAAQS or where the EPA has not determined that the area contributes to a 

nearby violation. The EPA must complete the initial area designation process within 2 years of 

promulgating a new or revised NAAQS, or may do so within 3 years under certain 

circumstances.1 This Technical Support Document (TSD) describes the EPA’s intent to designate 

certain areas in Tennessee as unclassifiable for the 2012 primary annual fine particle NAAQS 

(2012 annual PM2.5 NAAQS).2

Under section 107(d), states are required to submit area designation recommendations to the 

EPA for the 2012 annual PM2.5 NAAQS no later than 1 year following promulgation of the 

NAAQS, or by December 13, 2013. In December 2013, Tennessee recommended that Knox 

County be designated “unclassifiable” and all other counties in the State be designated as 

“unclassifiable/attainment” for the 2012 annual PM2.5 NAAQS. However, a recent EPAconducted technical systems audit of Tennessee’s monitoring program revealed data

completeness issues for several areas across the State.

3 Given these data completeness issues, the 

 

1 Section 107(d) of the CAA requires the EPA to complete the initial designation process within 2 years of 

promulgation of a new or revised NAAQS, unless the Administrator has insufficient information to make initial 

designation decisions in the 2-year time frame. In such circumstances, the EPA may take up to 1 additional year to 

make initial area designation decisions (i.e., no later than 3 years after promulgation of the standard).

2 On December 14, 2012, the EPA promulgated a revised primary annual PM2.5 NAAQS (78 FR 3086, January 15, 

2013). In that action, the EPA revised the primary annual PM2.5 standard, strengthening it from 15.0 micrograms per 

cubic meter (μg/m3) to 12.0 μg/m3.

3 Memorandum from Liz Naess, Group Leader, Air Quality Analysis Group, US EPA Office of Air Quality 

Planning and Standards, to EPA Docket EPA-HQ-OAR-2012-0918, Air Quality Designations for the 2012 PM2.5
2

EPA cannot determine whether the counties with the incomplete monitoring data are meeting or 

not meeting the NAAQS. Because the EPA cannot make a final regulatory determination about 

whether a violation exists in those counties with incomplete data, in some cases the EPA is also 

not able to determine whether counties nearby to those counties with incomplete monitoring data 

contribute to a nearby violation. Where data completeness issues remain unresolved prior to the 

EPA Administrator’s final determination on designations for the 2012 PM2.5 NAAQS, the EPA 

intends to designate the affected areas as “unclassifiable.” 

After considering Tennessee’s recommendations and based on the EPA’s assessment of available 

information as described in this TSD, the EPA intends to designate the areas identified in Table 1 

as unclassifiable for the 2012 annual PM2.5 NAAQS. Detailed analyses follow for each of the 

identified areas.

Table 1. EPA’s Intended Unclassifiable Areas for the 2012 annual PM2.5 NAAQS

Area Tennessee’s 

Recommendations

EPA’s Intended Unclassifiable 

Counties

Clarksville Unclassifiable/Attainment Montgomery and Stewart 

Counties

Kingsport Unclassifiable/Attainment Hawkins and Sullivan Counties

Knox County Unclassifiable Unclassifiable

Memphis Unclassifiable/Attainment Shelby, Fayette and Tipton 

Counties

Rest of State of 

Tennessee Unclassifiable/Attainment

Remaining counties in the State 

of Tennessee with the exception 

of Hamilton, Marion and 

Sequatchie Counties in the 

Chattanooga Area

However, if future valid air quality data obtained by Tennessee or other relevant states provides 

adequate basis for determining the air quality status of these areas, in particular if reliable quality 

assured monitoring data become available that indicate that any of these areas are violating the 

standard, at that time the EPA will may initiate action to resdesignate such areas, including 

conducting a complete 5-factor analysis, including consideration of the location and magnitude 

of the identified violations. As a result of any such future analyses, the boundaries of the 

 

Standards, titled, “Initial Area Designations for the 2012 Revised Primary Annual Final Particle National Ambient 

Air Quality Standard: Tennessee Data Issues.”
3

nonattainment area will not necessarily be those that EPA uses to define the unclassifiable areas 

that EPA intends to promulgate now based on incomplete data.
4

Clarksville TN-KY Area

Clarksville is located in a bi-state CBSA that includes four counties: two counties in Tennessee

and two counties in Kentucky. Most of the urbanized portion of Clarksville is contained within 

Montgomery County, Tennessee. None of the counties in the CBSA have ever been designated 

nonattainment for any for the 1997 or 2006 fine particulate matter (PM2.5) national ambient air 

quality standard (NAAQS). The Clarksville CBSA and surrounding counties are shown in 

Figure 1, along with the location of point sources and air quality monitors.

Figure 1. Clarksville CBSA with Point Sources and Air Quality Monitor Locations

There is an attaining monitor in Christian County, Kentucky with a valid design value of 10.3 

ug/m3 for the 2011-2013 timeframe. Also, the PM2.5 air quality in the area has been steadily 

improving since the early 2000’s as evidenced by the downward trend of PM2.5 values measured 

at the monitors in the Clarksville area. This downward trend is shown in Figure 2. The 

Montgomery County, Tennessee monitor has an incomplete deign value of 9.6 ug/m3for the 

2011-2013 timeframe.
5

Figure 2. Clarksville Area Air Monitor Design Value (DV) Trends

The EPA evaluated PM2.5 and PM2.5-precursor emissions and related data from the counties in 

the Clarksville area. Table 2 provides a summary of this data. Montgomery and Stewart Counties 

have the majority of PM2.5 and precursor emissions, population and vehicle miles traveled 

(VMT). Montgomery County has a monitor with invalid data and an urbanized core around the 

City of Clarksville. Stewart County has a large point source (TVA Cumberland Fossil Plant) 

with over 2,500 tpy of PM2.5 emissions and over 7,600 tpy of SO2 emissions in the upwind 

direction of the Montgomery County monitor.

In Kentucky, Christian County and Trigg County are outlying areas that are located primarily 

downwind from the Montgomery County PM2.5 monitoring site. Christian County has an 

attaining PM2.5 monitor, and while the county population is nearly half that of Montgomery 

County, current growth is only about 3 percent. Trigg County has very low emissions of all 

pollutants (e.g., 28 tpy of SO2 and 389 tpy of PM2.5), and the County’s population is relatively 

small at about 5 percent for the area.

0

2

4

6

8

10

12

14

16

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Clarksville DVs

Christian Cty, KY Montgomery Cty, TN - 471251009 2012 PM2.5 NAAQS
6

Table 2. Summary statistics for the Clarksville, TN-KY CBSA 

Montgomery Stewart Christian Trigg

State Tennessee Tennessee Kentucky Kentucky

Core urbanized 

county or outlying? Core Outlying Outlying Outlying

SO2 Emissions 

(tpy) 1,529 7,740 77 28

PM2.5 emissions 

(tpy) 1,018 2,452 947 389

Population 173,375 13,340 74,138 14,355

Population (% of 

CBSA) 63% 5% 27% 5%

Population growth 

(2000 – 2010) 29% 8% 3% 14%

VMT (Millions) 1,467 166 912 218

VMT (% of CBSA) 53% 6% 33% 8%

The EPA also evaluated the meteorology in the area by evaluating wind data collected at the Fort 

Campbell Airport. Figure 3 provides a wind rose created five years of data from 2009-2013. The 

predominant winds blow from the southwest and south directions. These predominant wind 

directions do not support contribution of emissions from the Kentucky counties to the PM2.5 air 

quality in the Tennessee areas.
7

Figure 3. Wind Rose Data for the Clarksville TN-KY Area

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Fort Campbell Airport

2009-2012

COMMENTS: COMPANY NAME:

MODELER:

DATE:

7/28/2014

PROJECT NO.:

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 30.05%

TOTAL COUNT:

43443 hrs.

CALM WINDS:

30.05%

DATA PERIOD:

Start Date: 1/1/2009 - 00:00

End Date: 12/31/2013 - 23:00

AVG. WIND SPEED:

2.56 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
8

Clarksville Area Conclusion:

As a result of our technical analysis of the Clarksville CBSA, the EPA is preliminarily 

determining that the Tennessee counties of Montgomery and Stewart be designated 

unclassifiable along with most of the State of Tennessee due to the ambient monitoring data 

quality issues, including an invalid 2013 design value at the Montgomery County monitor. The 

EPA is agreeing with the recommendation from Kentucky and are preliminarily recommending 

that Christian and Trigg Counties be designated attainment/unclassifiable. As discussed above, 

any potential violation at the Montgomery County monitor would be strongly influenced by the 

point sources in Stewart County, Tennessee. 
9

Kingsport-Bristol, TN-VA Area

Kingsport-Bristol is located in a bi-state CBSA that includes four counties and a city: two 

counties in Tennessee and two counties in Virginia, along with Bristol City which straddles the 

Tennessee and Virginia state line. Most of the urbanized portion of Kingsport-Bristol is 

contained within Sullivan and Hawkins Counties in Tennessee. None of the counties in the 

CBSA have ever been designated nonattainment for any for the 1997 or 2006 fine particulate 

matter (PM2.5) national ambient air quality standards (NAAQS). The Kingsport-Bristol CBSA 

and surrounding counties are shown in Figure 4, along with the location of point sources and air 

quality monitors.

Figure 4. Kingsport-Bristol CBSA with Point Sources and Air Quality Monitor Locations

There is an attaining monitor in Bristol City on the Virginia side of the state line with a valid 

design value of 9.0 ug/m3for the 2011-2013 timeframe. Also, the PM2.5 air quality in the area 

has been steadily improving since the early 2000’s as evidenced by the downward trend of PM2.5
10

values measured at the monitors in the Kingsport-Bristol area. This downward trend is shown in 

Figure 5. The Sullivan County, Tennessee monitor has an incomplete deign value of 9.3 ug/m3

for the 2011-2013 timeframe.

Figure 5. Kingsport-Bristol Area Air Monitor Design Value (DV) Trends

The EPA evaluated PM2.5 and PM2.5-precursor emissions and related data from the counties in 

the Kingsport-Bristol area. Table 3 provides a summary of this data. Sullivan and Hawkins 

Counties have the majority of PM2.5 and precursor emissions, population and VMT. Hawkins 

County also has four large point sources in the upwind direction of the Sullivan County monitor, 

two of which, TVA John Sevier Fossil Plant and Holston Army Ammunition Plant, have 

significant SO2 emissions of over 15,000 tpy and over 1,500 tpy, respectively.

In Virginia, Scott and Washington Counties and Bristol City have low emissions, population and 

VMT relative to Sullivan and Hawkins Counties. These are outlying areas that are located in the

primarily downwind direction from the Sullivan County PM2.5 monitoring site. Bristol City has 

an attaining PM2.5 monitor and low population and population growth of about 3 percent. Scott 

County has very low SO2 emissions of about 40 tpy and relatively low PM2.5 emissions of 306 

tpy. Although Scott County has 18 percent of the area’s population, the recent growth trend is 

negative. Washington County has very low emissions of all pollutants (e.g., 88 tpy of SO2 and 

104 tpy of PM2.5), and the County’s population is relatively small at about 6 percent for the area.

0

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4

6

8

10

12

14

16

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Kingsport DVs

Bristol City, VA Sullivan Cty., TN 2012 PM2.5 NAAQS
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Table 3. Summary statistics for the Kingsport-Bristol, TN-VA CBSA 

Hawkins Sullivan Bristol City Scott Washington

State Tennessee Tennessee Virginia Virginia Virginia

Core urbanized 

county or 

outlying?

Outlying Core Outlying Outlying Outlying

SO2 Emissions 

(tpy) 17,819 24,937 26 40 88

PM2.5 emissions 

(tpy) 892 3,036 946 306 104

Population 56,842 156,866 17,849 23,111 54,879

Population (% of 

CBSA) 18% 51% 6% 18% 6%

Population growth 

(2000 – 2010) 6% 3% 3% -1% 7%

VMT (Millions) 537 1,748 225 275 741

VMT (% of 

CBSA) 15% 50% 6% 21% 8%

The EPA also evaluated the meteorology in the area by evaluating wind data collected at the TriCities Regional Airport. Figure 6 is a wind rose created from five years of data from 2009-2013. 

The predominant winds blow from the west and southwest directions. These predominant wind 

directions do not support contribution of emissions from the Virginia areas to the PM2.5 air 

quality in the Tennessee areas.
12

Figure 6. Wind Rose Data for the Kingsport-Bristol TN-VA Area

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Tri-Cities Regional Airport

2009-2013

COMMENTS: COMPANY NAME:

MODELER:

DATE:

7/28/2014

PROJECT NO.:

NORTH

SOUTH

WEST EAST

2%

4%

6%

8%

10%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 53.14%

TOTAL COUNT:

43794 hrs.

CALM WINDS:

53.14%

DATA PERIOD:

Start Date: 1/1/2009 - 01:00

End Date: 12/31/2013 - 23:00

AVG. WIND SPEED:

1.60 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
13

Kingsport-Bristol Area Conclusion:

As a result of our technical analysis of the Kingsport-Bristol CBSA, the EPA is preliminarily 

determining that the Tennessee counties of Sullivan and Hawkins be designated unclassifiable 

along with most of the State of Tennessee due to the ambient monitoring data quality issues, 

including an invalid 2013 design value at the Sullivan County monitor. The EPA is agreeing with 

the recommendation from Virginia and is preliminarily determining that Scott and Washington 

Counties and Bristol City in Virginia be designated attainment/unclassifiable. As discussed 

above, any potential violation at the Sullivan County monitor would be strongly influenced by 

the point sources in Sullivan and Hawkins County, Tennessee. 
14

Memphis TN-MS-AR Area

Memphis is located in a tri-state CBSA that includes nine counties: three counties in Tennessee, 

five counties in Mississippi, and one county in Arkansas. Most of the urbanized portion of 

Memphis is contained within Shelby County, Tennessee, although there are pockets of 

urbanization that stretch into DeSoto County, Mississippi, and Crittenden County, Arkansas. 

None of the counties in the CBSA have ever been designated nonattainment for either the 1997 

or 2006 PM2.5 NAAQS. The Memphis CBSA and surrounding counties are shown in Figure 7, 

along with the location of point sources and air quality monitors.

Figure 7. Memphis TN-MS-AR CBSA with Point Sources and Air Quality Monitor Locations
15

There are attaining monitors in both DeSoto County and Crittenden County with valid design 

values for the 2011-2013 timeframe of 9.6 μg/m3and 10.6 μg/m3, respectively. Also, the PM2.5

air quality in the area has been steadily improving since the early 2000’s as evidenced by the 

downward trend of PM2.5 values measured at all of the monitors in the Memphis area, including 

the monitors in Shelby County prior to the time when data quality issues caused that data to be 

unreliable for final regulatory determinations (approximately 2008). This downward trend is 

shown in Figure 8. The Shelby County, Tennessee monitor has an incomplete deign value of 9.7

ug/m3for the 2011-2013 timeframe.

Figure 8. Memphis Area Air Monitor Design Value (DV) Trends

The EPA evaluated PM2.5 and PM2.5-precursor emissions and related data from the counties in 

the Memphis area. Table 4 provides a summary of this data. Shelby County has the majority of 

PM2.5 and precursor emissions, population and VMT. Shelby County also has four large sources 

just 8-12 miles upwind of the Shelby County monitor, including Cargill Corn Milling (330 tpy 

PM2.5 and 3,000 tpy SO2) and Allen Fossil Plant (415 tpy PM2.5 and 11,000 tpy SO2) as can be 

seen in the map of the Memphis area provided in Figure 7.

0

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4

6

8

10

12

14

16

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Memphis Area Design Values

PM2.5 NAAQS Shelby, TN-0047 (N.V. since 2008)

Shelby, TN-0014 Shelby, TN-0038

Shelby, TN-1004 Crittenden, AR-0004

Crittenden, AR-0005 DeSoto, MS-0002
16

Table 4. Summary statistics for the Memphis, TN-MS-AR CBSA 

Fayette Shelby Tipton Benton Desoto Marshall Tate Tunica Crittenden

State TN TN TN MS MS MS MS MS AR

Core 

urbanized 

county or 

outlying?

Outlying Core Outlying Outlying Core Outlying Outlying Outlying Core

SO2 

Emissions 

(tpy)

429 20,010 308 36 52 63 58 107 125

Primary 

Sulfate 

Emissions 

(tpy)

10 140 8 10 29 6 6 8 11

PM2.5

emissions 

(tpy)

790 4,042 874 475 1,419 1,064 651 1,471 1,854

Population 38,413 928,792 61,160 8,712 161,732 37,098 28,970 10,741 50,952

Population 

(% of CBSA) 3% 70% 5% 1% 12% 3% 2% 1% 4%

Population 

growth (2000 

– 2010)

33% 4% 19% 9% 51% 6% 14% 16% 0.2%

VMT 

(Millions) 540 8,562 417 190 1,798 683 365 237 866

VMT (% of 

CBSA) 4% 63% 3% 1% 13% 5% 3% 2% 6%

The EPA also evaluated the meteorology in the area by evaluating wind data collected at the 

Memphis International Airport. Figure 9 is a wind rose created from five years of data from 

2009-2013. The predominant winds blow from the south and southwesterly directions, with a 

smaller component of winds blowing from the north to the south. These wind patterns suggest 

the Shelby County monitor would be strongly be impacted by emissions from these large point 

sources in Shelby County.
17

Figure 9. Wind Rose Data for the Memphis TN-MS-AR Area

WRPLOT View - Lakes Environmental Software

WIND ROSE PLOT:

Memphis International Airport

2009-2013

COMMENTS: COMPANY NAME:

MODELER:

DATE:

7/28/2014

PROJECT NO.:

NORTH

SOUTH

WEST EAST

3%

6%

9%

12%

15%

WIND SPEED 

(m/s)

 >= 11.1

 8.8 - 11.1

 5.7 - 8.8

 3.6 - 5.7

 2.1 - 3.6

 0.5 - 2.1

Calms: 16.22%

TOTAL COUNT:

43822 hrs.

CALM WINDS:

16.22%

DATA PERIOD:

Start Date: 1/1/2009 - 00:00

End Date: 12/31/2013 - 23:00

AVG. WIND SPEED:

3.35 m/s

DISPLAY:

 Wind Speed

Direction (blowing from)
18

In addition, the EPA evaluated speciated PM2.5 information collected at the Chemical Speciation 

Network monitor in the area (Figure 10). The PM2.5 speciation data and the derived urbanincrement analysis indicate the dominance of different contributing species in each quarter. The 

peak PM2.5 concentrations occur during the 3rd quarter of the calendar year (July-September) 

when sulfate and primary organic matter are the major urban increment components of the PM2.5

mass. Largely responsible for these peak concentrations are the emissions from Shelby County, 

which include 20,010 tpy of SO2 and 140 tpy direct sulfate. By comparison, the Mississippi and 

Arkansas counties of the CBSA have low overall emissions, and in particular they have 

emissions of SO2 and direct sulfate in the range of just 36 to 125 tpy and 6 to 29 tpy, 

respectively.

Figure 10. Quarterly Speciated Monitoring and Urban Increment Data for the Memphis Area

Memphis Area Conclusion:

As a result of our technical analysis of the Memphis CBSA, the EPA is preliminarily 

determining that the Tennessee counties of Shelby, Fayette and Tipton be designated 

unclassifiable along with most of the State of Tennessee due to the ambient monitoring data 

quality issues, including an invalid 2013 design value at the Shelby County monitor. The EPA is 

preliminarily determining that Crittenden County, Arkansas, and Benton, DeSoto, Marshall, Tate 

and Tunica Counties in Mississippi be designated unclassifiable/attainment, which agrees with 

the recommendations from Mississippi and represents a slight modification to the 

recommendation from Arkansas of attainment for Crittenden County. As discussed above, any 
19

potential violation at the Shelby County monitor would be strongly influenced by the point 

sources within Shelby County, Tennessee, particularly the much higher level of SO2 and direct 

sulfate emissions relative to the rest of the CBSA.