## Technical Support for the 2008 Ozone Standard Designation Recommendation for th e State of Mississippi

Mississippi Department of Environmental Quality Air Division March 20092 Executive Summary

DeSoto, Harrison and Jackson Counties in Miss issippi are the only counties in the state with monitors that are reading above th e 2008 National Ambient Air Quality Standard (NAAQS). Therefore, Missi ssippi is recommending that only DeSoto, Harrison and Jackson Counties be designated as non-attainment for the 2008 ozone NAAQS. Figure 1 below shows the location of all of the monitors in the state.

Figure 1. Mississippi Ozone Monitoring Locations3 EPA recommends that the Metropolitan Statistical Area (MSA) or Combined Statistical Area (CSA) serve as the star ting point for determining the geographic boundaries of an ozone non-attainment area. A dditionally, there are nine factors to be evaluated in making the boundary de termination. These factors are:

• Factor 1: Air quality data

• Factor 2: Emission data (location of sources and contribution to ozone concentrations)

• Factor 3: Population density and degr ee of urbanization (including commercial development)

• Factor 4: Traffic and commuting patterns

• Factor 5: Growth rates and patterns

• Factor 6: Meteorology (weat her/transport patterns)

• Factor 7: Geography/topography (mountain ranges or other air basin boundaries)

• Factor 8: Jurisdictional boundaries (e.g., counties, air districts, Reservations, metropolitan planning organizations)

• Factor 9: Level of control of emission sources

DeSoto, Marshall, Tate, and Tunica Countie s are all in the Memphis, Tennessee MSA. The Gulfport-Biloxi-Pascagoula CSA consists of George, Hancock, Harrison, Jackson and Stone Counties. An analysis of the nine factors determined that only DeSoto, Harrison and Jackson Counties shoul d be designated as non-attainment for the 2008 ozone NAAQS. The surrounding coun ties should be excluded from these non-attainment areas.4 

### Mississippi Counties in the Memphis MSA

DeSoto, Marshall, Tate and Tunica Counties are all part of the Memphis, Tennessee MSA. Mississippi is recomm ending that only DeSoto County be designated as nonattainment for the 2008 ozone NAAQS. Curre nt monitoring data indicate that the Hernando monitor, located in Desoto County, is not attaining the standard of 0.075 ppm. Figure 2 below shows the location of th e Hernando monitor in DeSoto County. Marshall, Tate, and Tunica Counties do not have monitors. They contribute little to the overall emissions in the area, and have si gnificantly lower populations and traffic; therefore, based on an analysis of the nine fact ors, Marshall, Tate, and Tunica Counties should not be included in the non-attainment designation.

Figure 2. Mississippi Counties and Monito ring Locations in the Memphis MSA5 

### Nine Factor Analysis for Missi ssippi Counties in Memphis MSA

Factor 1: Air Quality Analysis

The following table is data collected from the Hernando monitor in DeSoto County, Mississippi. The surroundi ng counties of Marshall, Tate, and Tunica do not have monitors.

4 th Annual Maximum 8-Hour Ozone County AIRS ID Site

2006 2007 2008 3-Year Average 2006-2008 DeSoto 28-033-0002 Hernando 87 84 74 81 Table 1. Hernando, MS Monitor Data

Factor 2: Location of Emissions Sources and Contribution to Ozone Concentrations

The Mississippi counties in the Memphis MSA have a small number of major emission sources as shown in Figure 3. DeSoto County has two facilities that are classified as major sources of Nitrogen Oxides (NOx) and three facilities classified as major sources of Volatile Organic Compounds (VOCs). Tate County has one major source of NOx and three major sources of VOCs. However, th ere are no major sources in Marshall or Tunica counties.6 Figure 3. Mississippi Major Emissi on Sources in the Memphis MSA The largest contributor of ozone precursor emissions in the area is Shelby County, Tennessee. Chart 1 gives a comparison of NOx and VOC emissions from all source categories in the four Missi ssippi counties and Shelby C ounty, Tennessee. The total emissions from Marshall, Tate and Tunica Counties are small in comparison to DeSoto County’s emissions and very small in comparison to Shelby County, Tennessee’s emissions. Based on the emission data, Ma rshall, Tate, and Tunica County would not have a significant contributi on to the Hernando monitor.

County Emissions - 2005

0 10,000 20,000 30,000 40,000 50,000 60,000

DeSoto Marshall Tate Tunica Shelby, TNTons per year
Nox (tons) VOC (tons)

Chart 1. NOx and VOC emission comp arison for Memphis MSA (2005 NEI)7 Factor 3: Population Density and Degree of Urbanization

Marshall, Tate and Tunica Counties are belo w the national average for population density with little or no urbanized areas. They ar e much lower than DeSoto County’s population density and degree of urbanization. Chart 2 compares population de nsities and Chart 3 compares degrees of urbanization for the Memphis MSA.

Population Density

0 200 400 600 800 1,000 1,200 1,400

DeSoto Marshall Tate Tunica ShelbyPopulation per square mile

Density U.S. Average

Chart 2. Population Density of Memphis MSA (2000 census data)

Degree of Urbanization

0 100,000 200,000 300,000 400,000 500,000 600,000 700,000 800,000 900,000 1,000,000

DeSoto Marshall Tate Tunica Shelby Rural Population Urban Population

Chart 3. Degree of Urbanization for Memphis MSA (2000 census data)8 Factor 4: Traffic and Commuting Patterns

The overall amount of traffic is minor in Marshall, Tate, and Tunica Counties and their commuting patterns do not indicate an impact on the DeSoto County monitor. The amount of traffic is measured Vehicle Mile s Traveled (VMT) and is developed by the Mississippi Department of Transportation. Ch art 4 compares the traffic data for the Mississippi Counties in the Memphis MSA. Data from the 2000 census was used to determine the commuting patterns. Chart 5 summarizes this information and demonstrates that the reside nts in Marshall, Tate and T unica counties commute primarily within their own county. Cons equently, the traffic from these counties would have no substantial impact on the monitor in Hernanado.

County Traffic

0 200,000,000 400,000,000 600,000,000 800,000,000 1,000,000,000 1,200,000,000 1,400,000,000 1,600,000,000 1,800,000,000 2,000,000,000

DeSoto Tate Tunica MarshallVMT Other Principal Arterials Freeway
Interstate

Chart 4. Traffic Data for the Missi ssippi Counties in the Memphis MSA (2005 HPMS Data)9 Commuting Patterns

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000 450,000 DeSoto Marshall Tate Tunica Shelby Work County

Commuters DeSoto

Marshall

Tate

Tunica
Shelby

Chart 5. Commuting Patterns for Memphis MSA (2000 Census)10 Factor 5: Growth Rates and Patterns

Growth rates were determined for DeSoto, Marshall, Tate, and T unica Counties using the 2000 census figures and the 2007 census estimates. Table 2 shows that Marshall, Tate and Tunica counties have not e xperienced significan t growth since the 2000 census data.

County 2000 Census Population 2007 Census Estimate Increase % annual Growth

DeSoto 107,199 149,393 42,194 5.6% Marshall 34,993 36,695 1,702 0.7%

Tate 25,370 26,910 1,540 0.9% Tunica 9,227 10,453 1,226 1.9%

Table 2. Population Growth Rates for Mi ssissippi Counties in the Memphis MSA

Factor 6: Meteorology (Weather and Transport)

Backward trajectories were created usi ng the National Weather Service’s HYSPLIT program to examine the path air parcels fo llowed for the 24 hours prior to midnight for each day that the maximum 8-hour ozone concentration exceeded 75 ppb for the period 1999 - 2008 in DeSoto County. The results from this backward trajectory analysis show that 76% of the non-stagnant b ack trajectories that ended in Hernando originated from the north or northeast. This indicates emissi ons from Marshall, Tate, and Tunica counties contribute little to the Hernando monitor on the higher ozone days.

Factor 7: Geography and Topography

The Mississippi counties in the Memphis MSA ar e located in northwes tern Mississippi. DeSoto and Tunica counties bord er the Mississippi River. DeSoto and Marshall Counties border Tennessee while Tate is directly sout h of DeSoto County. The topography of the area ranges from the flat lowland of the Missi ssippi Delta in the west to rolling hills in the central and eastern part of the MSA.

Factor 8: Jurisdictional Boundaries

DeSoto, Marshall, Tate, and Tunica Countie s are within the Memphis MSA. DeSoto County is within the Memphi s Metropolitan Air Quality Co ntrol Region. Tunica County is within the Mississippi Delta Air Quality Control Region. Marshall and Tate counties are within the Nort heast Mississippi Air Quality C ontrol Region. The Mississippi Department of Environmental Quality is res ponsible for monitoring air quality in these counties.11 Factor 9: Level of Control of Emissions No additional emissions standards apply to th is area beyond federal and state standards. Considering the low air emissions in Marsha ll, Tate, and Tunica Counties, there are no specific measures that could be applied that would yield significant reductions.12 

### Gulfport-Biloxi-Pascagoula CSA

Mississippi is recommending that only Jack son and Harrison Counties in the GulfportBiloxi-Pascagoula CSA be designated as non-attainment for the 2008 ozone NAAQS. Current monitoring data indicates that the Pascagoula monitor in Jackson County and the Gulfport monitor in Harrison County are not attaining the standard of 0.075 ppm. The surrounding counties of George and Stone do not have monitors. The Hancock County monitor has not been in operation since it 2005, but should be in operation for the 2009 ozone season. Based on an analysis of the nine factors, George, Hancock and Stone Counties should not be included in the non- attainment designation. These counties contribute little to the overall emissions in the area and have significantly lower populations and traffic. Figur e 4 below shows the monitoring locations in the GulfportBiloxi-Pascagoula CSA.

Figure 4. Gulfport-Biloxi-Pascagoula CSA Monitoring Locations13 Nine Factor analysis for Gu lfport-Biloxi-Pascagoula CSA

Factor 1: Air Quality Analysis

The following table is data collected from the Gulfport and Pascagoula monitors in Mississippi. The surrounding c ounties of George and Stone do not have monitors. The Hancock County monitor has not operat ed since 2005 due to damage caused by Hurricane Katrina. This monitor will resume operation for the 2009 ozone season.

4

th Annual Maximum 8-Hour Ozone County AIRS ID Site

2006 2007 2008 3-Year Average 2006-2008

Harrison 28-047-0008 Gulfport 84 81 78 81 Jackson 28-059-0006 Pascagoula 82 78 76 78 Table 3. Gulfport and Pascagoula, MS Monitoring Data14 Factor 2: Location of Emissions Sources and Contribution to Ozone Concentrations

Figure 4 shows the location of the major pointsources of NOx or VOC in the GulfportBiloxi-Pascagoula CSA. Chart 6 gives the to tal emissions from all sources in each county. The total emissions in Hancock, Geor ge and Stone Counties are much less than the emissions in Jackson and Harrison Countie s. Due to the location and size of the sources in Hancock, George and Stone Countie s, they would not c ontribute significantly to the ambient ozone levels in Harrison or Jackson Counties.

Figure 5. Major Emission Sources in the Gulfport-Biloxi-Pascagoula CSA15 County Emissions

0 5,000 10,000 15,000 20,000 25,000 30,000 35,000 40,000

Hancock Harrison Jackson George Stonetons per year Nox (tons) VOC (tons)

Chart 6. NOx and VOC emission comparis on for Gulfport-Biloxi-Pascagoula CSA (2005 NEI)16 Factor 3: Population Density and Degree of Urbanization

Hancock, George and Stone Counties are be low the national average for population density with little or no urbanized areas. Th ey are much lower than Harrison and Jackson Counties’ population density and degree of urbanization. Chart 7 compares population densities and Chart 8 compares degrees of urbanization for the Gulfport-BiloxiPascagoula CSA.

Population Density

0 50 100 150 200 250

Hancock Harrison Jackson George Stonepopulation/square mile

Density U.S. Average

Chart 7. Population Density of Gulfpo rt-Biloxi-Pascagoula CSA (2000 Census)

Degree of Urbanization

0 50,000 100,000 150,000 200,000 250,000 300,000 350,000

Hancock Harrison Jackson George StonePopulation Rural Population Urban Population

Chart 8. Degree of Urbanization fo r Gulfport-Biloxi-Pascagoula CSA (2000 Census)17 Factor 4: Traffic and Commuting Patterns

The overall amount of traffic in Hancock, Ge orge and Stone Countie s is significantly lower than the VMT in Harrison and Jackson Counties. The amount of traffic is measured in Vehicle Miles Traveled (VMT) and is developed by the Mississi ppi Department of Transportation. Chart 9 compares the traffic data for the Gulfport-Biloxi-Pascagoula CSA. Data from the 200 Census was used to determine the commuting patters. Chart 10 summarizes this information and demonstrates that the residents in Hancock, George, and Stone Counties commute primarily within th eir own county. Consequently, the traffic from these counties would have no substant ial impact on the monitors in Gulfport and Pascagoula.

County Traffic

0 500,000,000 1,000,000,000 1,500,000,000 2,000,000,000 2,500,000,000

Harrison Jackson Hancock George StoneVMT Other Principal Arterials Freeway
Interstate

Chart 9. Traffic Data for Gulfport-B iloxi-Pascagoula CSA (2005 HPMS Data)18 Commuting Patterns

0 20,000 40,000 60,000 80,000 100,000 120,000 Hancock Harrison Jackson

George

Stone Work County

Commuters Hancock
Harrison
Jackson George
Stone

Chart 10. Commuting Patterns for Gulfpo rt-Biloxi-Pascagoula CSA (2000 Census)19 Factor 5: Growth Rates and Patterns

Comparing the 2000 census and 2007 census estima tes, there has been negative growth in Hancock, Harrison and Jackson Counties due to the devastation from Hurricane Katrina. There has been positive growth in George and Stone Counties; however, the growth is minimal and these counties have low populations.

County Population (2000 census) 2007 Census Estimate Increase % Annual Growth

Hancock 42,967 39,687 -3,280 -1.1% Harrison 189,601 176,105 -13,496 -1.0% Jackson 131,420 130,098 -1,322 -0.1% George 19,144 21,937 2,793 2.1%

Stone 13,622 15,731 2,109 2.2% Table 4. Population Growth Rates for Gulfport-Biloxi-Pascagoula CSA

Factor 6: Meteorology (Weather and Transport)

Backward trajectories were created usi ng the National Weathe r Service’s HYSPLIT program to examine the path air parcels fo llowed for the 24 hours prior to midnight for each day that the maximum 8-hour ozone concentration exceeded 75 ppb for the period 1999 - 2008 in Harrison and Jackson counties. Th e results from this backward trajectory analysis show that 40-45% of the back traject ories that ended in Gu lfport or Pascagoula demonstrated a diurnal land/sea breeze circul ation along the coast. Only 9-14% of the back trajectories originated from the north or northwest. This i ndicates emissions from George, Hancock and Stone Counties contri bute little to the Gu lfport and Pascagoula monitors on the higher ozone days.

Factor 7: Geography and Topography

The Gulfport-Biloxi-Pascagoula Combined Stat istical Area is locate d in southeastern Mississippi. Hancock, Harrison, and Jackson Counties border the Gulf of Mexico. George and Jackson Counties border Alabama while Hancock County bor ders Louisiana. The topography ranges from rolling hills in the northern portion of this region to the beach in the southern portion.

The diurnal land-sea br eeze recirculation, caused by the prox imity of the Gulf of Mexico and by weather conditions w ith light steering winds, results in higher ozone concentrations generally along the coastline. Historical inland monitoring data (5-10 miles) in the coastal counties revealed little effect on ozone concen trations from this recirculation.20 Factor 8: Factor Jurisdictional Boundaries

George, Hancock, Harrison, Jackson, and Stone counties are within the Biloxi-GulfportPascagoula Combined Statistical Area. These counties are also locate d within the Mobile – Pensacola - Panama City - Southern Mi ssissippi Air Quality Control Region. The Mississippi Department of Environmental Qu ality is responsibl e for monitoring air quality in these counties.

Factor 9: Level of Control of Emissions

No additional emissions standards apply to th is area beyond federal and state standards. Considering the low air emissions in George , Hancock and Stone Counties, there are no specific measures that could be applied that would yield significant reductions.