## GEORGIA DEPARTMENT OF NATURAL RESOURCES



# ENVIRONMENTAL PROTECTION DIVISION Air Protection Branch Ambient Monitoring Program

Analysis of Rossville PM 2.5 

# DataGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 1

1.0 Introduction

In 2007, the Georgia Department of Natural Resources, Environmental Protection Division (GA EPD) underwent changes to its Rossville ambient air monitoring location. Due to construction at its original location (Rossville Health Center, 1430 Suggs Street, site ID# 13-295-0002), GA EPD was required to move the monitors. The original location (latitude/longitude 34.966557/- 85.297229) and the new location (601 Maple Street, Lot #6, with latitude/longitude of 34.978900/-85.300900) both reside in Walker County, in the Chattanooga Tennessee-Georgia Metropolitan Statistical Area (MSA).

The EPA’s Code of Federal Regulations allows lo cation changes to State and Local Monitoring Stations (SLAMS) monitors due to logistical problems beyond the State’s control. When moved, these ambient air monitoring stations may keep t he same Air Quality System identification (AQS ID) if the new station is located within one mile of the previous site. This regulation states: 40CFR 58.14 System Modification, Paragraph C (6) A SLAMS monitor not eligible for removal under any of the criteria in paragraphs (c)(1) through (c)(5) of this section may be moved to a nearby location with the same scale of representation if logistical problems beyond the State's control make it impossible to continue operation at its current site.71 FR 61298, Oct. 17, 2006. GA EPD moved its monitoring location within a mile of the original location.

In 2007, GA EPD met with EPA regarding the PM 2.5 sites in the Chattanooga, TN-GA MSA. GA EPD met with Doug Neeley, Branch Chief of the Air, Pesticides, and Toxics Grant ManagementUnit of Region 4 to discuss deleting sites of close proximity in the Chattanooga TennesseeGeorgia MSA nonattainment area (particularly Rossville). The outcome of the meeting was that GA EPD was required to maintain a monitoring site in Rossville. Later, GA EPD was notified of construction to the original Rossville site location. The roof of the Rossville Health Center was going to be removed and replaced with a new slanted roof. The new roof configuration would no longer support the ambient air monitoring equipment. GA EPD closed the site with standard site operating procedures found in 40CFR58.14, and began the process of establishing a new location for the monitor that would meet siting cr iteria. The Rossville-Maple Street site is within a mile of the original site, and met siting criteria thus allowing GA EPD to maintain the original site, or AQS, ID number. The site was prepared with a platform, power, and a fence.

During the time from June 12, 2007 to November 13, 2007, while the new site was being established, no data was collected with the PM 2.5 FRM sampler at the Rossville site. This caused the data collection to be non-continuous for the year of 2007. This void of data, in turn, caused the calculation of the three-year PM 2.5 design value from 2006-2008 to not fulfill requirements. To demonstrate attainment, 40CFR50 Appendix N requires a minimum of 75% data recovery per quarter for three consecutive years. If the minimum data recoveries are not met, the rules allow for data substitution. Due to the data loss from moving the site, GA EPD is not able to meet the minimum data recovery. Data substitution allowed by the rules does not adequately represent the true ambient air quality of Rossville. The purpose of this document is to discuss the lapse in PM 2.5 FRM data and resulting research used to develop a weight of evidence for an alternative method of data substitution in order to determine attainment/nonattainment of the Rossville site.

In the development of this document, attention wa s given to several rules and other factors. Many considerations were made involving the number of required PM 2.5 monitors in an MSA, rules for spatial averaging in an area, rules for meeting data completeness, rules for allowing an approved shut down due to loss of site, and meet ing all of EPA’s requirements. GA EPD also drew from past experience.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 2

In 2002, the Augusta-Medical College site (13-245-0005, the design value site) had incomplete data for the third quarter. The site was shut down due to construction. A calculation of the number of possible sampled dates compared to the actual sample dates finds a total of 16% data recovery for the third quarter, with 27% in July, 0% in August, and 20% in September. However, the Augusta-Bungalow Road site (13-245-0091) met the minimum requirements for sampling and attainment, and the Augusta area was designated unclassifiable. Following the Augusta precedence, the incomplete data from the Rossville site should not be used to designate the Chattanooga, TN-GA MSA as nonattainment, but at the maximum unclassifiable. The reason for this classification is the Rossville site is not the design value site as the Medical College site was in Augusta, and the Rossville site was shut down due to loss of a monitoring site just as the Augusta site.

Another important consideration in the development of this document is the number of PM 2.5 monitors required in the Chattanooga, TN-GA MSA. According to the U.S. Census Bureau, the Chattanooga, TN-GA MSA population for 2000 was 465,161. Table D-5 of Appendix D to 40CFR58 of the Federal Register states that if the MSA has a population of 500,000 to 1,000,000, and the most recent 3-year design value is >/=85% of any PM 2.5 NAAQS, there should be two PM 2.5 monitors located within that MSA (71 FR 61321, October 17, 2006). Assuming the population is now within that 500,000 to 1,000,00 range, this would mean that the Chattanooga, TN-GA MSA would need two PM 2.5 monitors. There are currently four PM 2.5 monitors in the Chattanooga, TN-GA MSA, with two additional monitors in the MSA than required by the Federal Register. During the June through November 2007 timeframe, there were three other PM 2.5 monitors in the Chattanooga, TN-GA MSA collecting PM 2.5 data.

While GA EPD is not proposing to use spatial averaging for an attainment designation purpose, a spatially averaged analysis may be useful in the weight of evidence for the appropriate designation of the Rossville site and the Chattanooga, TN-GA MSA. 40CFR50, Appendix N, describes the method for determining if two samplers are reporting data from the same airmass, and whether that data should be averaged to reflect one data point. The method for spatial averaging states: “For single site comparisons, 3 years of valid annual means are required to produce a valid annual standard design value. In the case of spatial averaging, 3 years of valid spatially averaged annual means are required to produce a valid annual standard design value. Designated sites with less than 3 years of data shall be included in annual spatial averages for those years that data completeness requirements are met. A year meets data completeness requirements when at least 75 percent of the scheduled sampling days for each quarter have valid data.” For the 2007 PM 2.5 FRM data at the Rossville site, there were 26 samples collected in the first quarter, 18 samples collected in the second quarter (with one exceptional event), 0 samples collected in the third quarter, and 14 samples collected in the fourth quarter. This does not add up to 75 percent for the 2007 data. However, the Rossville PM 2.5 FRM data met the 75 percent data completeness rules for the 2006 and 2008 years of data.

This document will demonstrate, through data analysis on the Siskin Drive and Maxwell Road/Tombras Avenue PM 2.5 sites within the Chattanooga, TN-GA MSA, alternatives for calculating the PM 2.5 2006-2008 design value at the Rossville site. Details for each site used in the comparison are given, along with maps of each site and distances from the Rossville site. Pearson Product-Moment Correlations were calculated for all the data collected, for the months that data was not collected at the Rossville site, and for each individual quarter of data collected and shown in this document. A comparison of annual means and differences between annual means and spatial averages were calculated and shown in this document. Linear regressions were plotted on all available paired data and resulting scatter plots and R 2 values are shown. A box plot was graphed and displayed in the document. Pearson Product-Moment Correlation,Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 3

linear regressions, R 2 values, quarterly percent differences, quarterly absolute differences, and quarterly percent contributions were all calculated on select speciation data and shown in this document. Sources of emissions affecting each site were examined and a source apportionment model was run on the speciation data. An investigation of the meteorological conditions affecting the sites were investigated and summarized. A trend of each data point is examined with a line graph of all the data. A removal bias tool was applied to the Rossville site in order to show how the available data would be affected by its removal.

Initially, all four PM 2.5 FRM sites within the Chattanooga, TN-GA MSA were analyzed, including the Soddy Daisy site (47-065-1011). The analyses with the Soddy Daisy site were found to neither add nor detract from the research. Therefore, in order to focus on the sites that added value to the research, the Soddy Daisy site comparisons were not included in this document.

With the research herein, GA EPD will show that a 2006-2008 annual design value could be calculated for the Rossville PM 2.5 FRM sampler using data substituted from the Siskin Drive or the Maxwell Road/Tombras Avenue site, and that this is a valid way of representing the data and making the attainment designation. As stated in paragraph 4.1(c) of 40CFR50, Appendix N,

“ The use of less than complete data is subject to the approval of EPA, which may consider factors such as monitoring site closures/moves, monitoring diligence, and nearby concentrations in determining whether to use such data .’ From the weight of evidence provided, it is anticipated that EPA will agree with GA EPD’s findings, and that EPA will proceed with the modified data substitution to calculate the design value for the Chattanooga, TN-GA MSA.

1.1 Site History

GA EPD began monitoring with a PM 2.5 FRM sampler at the Rossville-Health Center location ( Figure 1) on January 1, 2000. A PM 2.5 speciation monitor began monitoring on March 23, 2005, and a continuous PM 2.5 monitor was installed on January 24, 2007. GA EPD made an extra effort to remain at the same location for longevity of data collection. On July 16, 2004, Walker County Commissioner, Bebe Hiskell, sent a letter to GA EPD requesting that the monitors be moved due to refurbishing the building. Three suggestions were presented as new locations for where the monitors could be moved. However, all three suggestions were too far outside the same air mass and lacked assurance that the same representative data would be collected. GA EPD convinced Commissioner Hiskell that it would be better to continue monitoring at the original location. At that time, it was decided that the construction would not be undertaken. However, by 2007 the construction to the roof was initiated. The resulting construction would be to replace the flat roof with a pitched roof. The PM 2.5 FRM sampler was discontinued on June 11, 2007 at the Rossville-Health Center location according to 40CFR 58.14 System Modification, Paragraph C (6). Therefore, GA EPD needed to find a new location for monitoring that would be within one mile of the original location, to be in the same air mass, and to meet EPA siting criteria. After exploration of a few possibilities, a new site was found by August of 2007, and GA EPD was given permission to use the land.

On August 13, 2007 GA EPD received a letter from EPA (Danny France, Chief Air and Superfund Section of U.S. EPA Region 4) stating that on August 1, 2007, Greg Noah and Jerry Burger of U.S. EPA Region 4 Science and Ecosystem Support Division evaluated the proposed site location. The findings of the evaluation were that the site location could meet siting requirements of 40CFR58 Appendix E, and represent a neighborhood scale according to 40CFR58 Appendix D. On August 29, 2007, GA EPD met with electrical and general contractors to finalize site build details. Purchase orders were placed on September 10 and September 12 of 2007 for the work to be done by the general contractor and electrical contractor, respectively.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 4

On September 25, 2007, the deck and fence building process began, and on September 28, 2007, the electrical work process began. On October 9, 2007, the deck and fence building process was complete, and on October 11, 2007, the electrical work process was complete. An application and setting up service with the power company was placed on October 17, 2007 and power was initiated on October 25, 2007. At the end of October 2007, the site operator was notified that the site was ready for occupancy and start up. The samplers were set up at the new location, and the site was restarted November 14, 2007. The new location is 601 Maple Street, Lot #6, Rossville, GA 30741 ( Figure 2).

1.2 Site Details

The followin g information provides the site details for both the original Rossville site location and the new Rossville site location. Included in the list of information is the site name, site identification number, address, latitude and longitude, date of site establishment and MSA represented. Following the list of site information are site photographs taken in each cardinal direction.

Original Site: Rossville Health Center Site ID: 13-295-0002 Address: 1430 Suggs Street, Rossville, Walker County, GA 30741 Latitude/Longitude: 34.966557/-85.297229 Site Established: January 1, 1967 MSA Represented: Chattanooga Tennessee-Georgia Metropolitan Statistical AreaGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 5

Figure 1: Rossville-Health Center Site Directional Photographs 

### South West North

EastGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 6

New Site: Rossville-Maple Street Site ID: 13-295-0002 Address: 601 Maple Street, Lot #6, Rossville, Walker County, GA 30741 Latitude/Longitude: 34.978900/-85.300900 Site Re-Established: November 14, 2007 MSA Represented: Chattanooga Tennessee-Georgia Metropolitan Statistical Area

Figure 2 : Rossville-Maple Street Site Directional Photographs 

### North

West

South EastGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 7

1.3 Sites Used in Comparison

Two PM 2.5 FRM sites within the Chattanooga Tennessee-Georgia MSA were used for comparison with the PM 2.5 data collected at the Rossville site. These sites were chosen for two reasons. First, the close proximity of the sites to the Rossville site location would suggest collection of similar data. Second, all four of the sites represent the same MSA, or the same airshed. The first site used for comparison is the Maxwell Road/Tombras Avenue site. It is located currently at 1517 Tombras Avenue and was originally located at 1510 Maxwell Road in East Ridge, TN. It has the site ID 47-065-0031, with latitude and longitude of 34.994555/- 85.242872. The Maxwell Road/Tombras Avenue site has collected PM 2.5 FRM data since May 6, 1999. The second site used for comparison to the Rossville site is the Siskin Drive site, located at the Riverside Substation, 911 Siskin Drive in Chattanooga, TN. It has the site ID 47- 065-4002, with latitude and longitude of 35.050928/-85.292975. The Siskin Drive site has collected PM 2.5 FRM data since January 1, 1999, PM 2.5 speciation data including PM 2.5 mass readings since November 27, 2001, and PM 2.5 continuous data since March 26, 2004. Both sites are in Hamilton County, TN.

1.4 Site Maps

To view each site location and observe the i mmediate surroundings at each site used in comparison with the Rossville site, a map of each site was derived from Google Earth. Distances from the Rossville site to the surrounding sites were also examined. The first map shows the original location of the Rossville site, at the Rossville Health Center. This location of the Rossville-Health Center sites is a suburban setting, with residential areas in the immediate surroundings. Figure 4 shows a map of the Maxwell Road/Tombras Avenue site. The Maxwell Road/Tombras Avenue site is located in an urban area, with businesses on the immediate northern side and a residential setting to the immediate south. Figure 5 maps the location of the Siskin Drive site. The location of the Siskin Drive site is also in an urban area, with its immediate surroundings of businesses and industries. Figure 6 maps the new Rossville location, at the Maple Stree t site. The Rossville-Maple Street location is in a suburban area like the RossvilleHealth Center site. The Rossville-Maple Street site’s immediate surroundings include a residential setting to the east and undeveloped land to the west.

Figure 7 and Figure 8 show the distances between the sites. Figure 7 shows the distance from the Rossville-Health Center site to the Maxw ell Road/Tombras Avenue site, the Siskin Drive site, and the Rossville-Maple Street site. The distance from the Rossville-Health Center site to the Maxwell Road/Tombras Avenue site is 3.63 miles. The distance from the Rossville-Health Center site to the Siskin Drive site is 5.8 miles. The distance from the Rossville-Health Center site to the Rossville-Maple Street site is 0.89 miles.

Figure 8 shows the distance between the Rossville-Maple Street site and the Maxwell Road/Tombras Avenue site, and the distance betw een the Rossville-Maple Street site and the Siskin Drive site for reference. The distance from the Rossville-Maple Street site to the Maxwell Road/Tombras Avenue site is 3.5 miles. The distanc e from the Rossville-Maple Street site to the Siskin Drive site is 5.0 miles. All maps and distances were derived from Google Earth.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 8

Figure 3: Rossville-Health Center Map

Figure 4: Maxwell Road/Tombras Avenue MapGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 9

Figure 5: Siskin Drive Map

Figure 6: Rossville-Maple Street MapGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 10

3.63 miles

0.89 mile 5.81 miles

Figure 7: Distance from Rossville-Health Center Site

3.5 mile s 5.0 miles

Figure 8: Distance from Rossville-Maple Street SiteGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 11

2.0 Analyses Performed

To better understand the relationship between the Rossville site and the Tennessee sites, several different analyses were performed. Pearson Product-Moment Correlations were calculated for the PM 2.5 data. This includes comparing PM 2.5 FRM data to PM 2.5 FRM data and PM 2.5 speciation mass readings. The correlations were calculated based on the whole data set beginning with the first sampling period that had coincident data points. Correlations of the PM 2.5 FRM data were performed on the years of data that were collected for particular months that the Rossville site did not collect data (June through November). Correlations were calculated for each quarter of PM 2.5 FRM data collected, as early as data was collected. Percent differences between annual means of PM 2.5 FRM data were calculated and graphed for each pair of sites. Percent differences for means across complete datasets were calculated for the PM 2.5 data (including FRM and speciation mass readings). Percent differences between annual means and spatial averages of annual means of PM 2.5 FRM data were examined. R 2 values with linear regressions were calculated and plotted on the PM 2.5 data (including FRM and speciation mass readings). Descriptive statistics and a box pl ot analysis was performed with SigmaStat and displayed. Select PM 2.5 speciation data at the Rossville and Siskin Drive sites was examined with Pearson Product-Moment Correlations, linear regressions and R 2 values, percent differences and absolute differences between each quarter of data, and percent contribution of each of the select species for the Rossville and Siskin Drive sites. Emission sources were examined with a source apportionment model perfor med on the speciation data collected at the Rossville and Siskin Drive sites. Meteorological data was analyzed in order to determine if sites in the same area would have been affected by the same meteorological patterns. Line graphs were examined, comparing each paired data point. A network assessment tool involving removal of a site was incorporated in order to show if the PM 2.5 FRM data collected at the surrounding sites is significantly different fr om the Rossville site. Techniques and procedures used for each of the analyses are explained within each section of the document.

Even though GA EPD is not proposing to use spatial averaging for Rossville’s PM 2.5 attainment designation, to show a weight of evidence following the rigorous spatial averaging guidelines seems beneficial. The above analyses were perform ed with these strict statistical tests as guidelines. 40CFR50
, Appendix N, states that: ‘2.0 Monitoring Considerations. (b) To qualify for spatial averaging, monitoring sites must meet the criterion specified in section 4.7.5 of appendix D of 40 CFR part 58 as well as the following requirements: (1) The annual mean concentration at each site shall be within 10 percent of the spatially averaged annual mean. (2) The daily values for each site pair shall yield a correlation coefficient of at least 0.9 for each calendar quarter. (3) All of the monitoring sites should principally be affected by the same major emission sources of PM 2.5 . For example, this could be demonstrated by site-specific chemical speciation profiles confirming all major component concentration averages to be within 10 percent for each calendar quarter. (4) The requirements in the paragraphs (b)(1) through (3) of this section shall be met for 3 consecutive years in order to produce a valid spatially averaged annual standard design value.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 12

Otherwise, the individual (single) site annual standard design values shall be compared directly to the level of the annual NAAQS.’ These guidelines helped GA EPD determine if there is a significant relationship between Rossville and any of the Tennessee sites, and if this relationship validates the use of additional methods for data substitution into the missing Rossville PM 2.5 measurements so as the data may be used for attainment designation.

2.1 Correlations

To follow th e guidance in Appendix N, the daily values for each site pair needed to yield a correlation coefficient of at least 0.9 for each calendar quarter. Correlations on corresponding PM 2.5 data were examined. Pearson Product-Moment Correlations were performed on PM 2.5 data, including FRM and speciation mass readings. The data used in the comparisons was retrieved from the U.S. EPA Air Quality System (AQS). To compare the data collected at each site, all the data was paired with the data from the other sampler on the days with the same sample date. If the data was given a null data code for a site for a sample date, or the dates did not match due to a make up sample, the data was taken out for both sites. The correlations were found using Excel. Pearson Product-Moment Correlations were performed on the total datasets, the particular months and seasons that the Rossville sampler did not, and on each quarter of PM 2.5 FRM data collection.

Pearson Product-Moment Correlations All Possible Data Included Dates* Correlation

Rossville PM 2.5 FRM vs. Maxwell Road PM 2.5 FRM 1/1/00 to 12/29/08 0.91362

Rossville PM 2.5 FRM vs. Siskin Dr PM 2.5 FRM 1/1/00 to 12/29/08 0.91609

Rossville PM 2.5 Speciation Mass vs. Siskin Drive PM 2.5 FRM 3/23/05 to 3/26/09 0.89754

Rossville PM 2.5 Speciation Mass vs. Siskin Drive PM 2.5 Speciation Mass 3/23/05 to 12/26/08 0.80974

Rossville PM 2.5 Speciation Mass vs. Maxwell Road PM 2.5 FRM 3/23/05 to 12/26/08 0.89476

*Excludes the missing data from 6/12/07 to 11/13/07

Table 1: Pearson Product-Moment Correlations

According to the Pearson Product-Moment Correlations derived from the different types of available data, it appears that the Rossville PM 2.5 FRM and Siskin Drive PM 2.5 FRM datasets show the strongest correlation, 0.91609. This is above the 40CFR50
, Appendix N, paragraph (2.0) (B) (2) regulation used as guidance stating that the quarterly correlations should be at least 0.9. The correlation between the Rossville PM 2.5 FRM and Maxwell Road/Tombras Avenue PM 2.5 FRM datasets is 0.91362, also above the 0.9 guidance for quarterly correlations. All of the correlations are relatively high, with 0.80974 being the lowest correlation found between the two PM 2.5 speciation mass readings at the Rossville and Siskin Drive sites.

A Pearson Product-Moment Correlation was derived for each month (June through November) that PM 2.5 data was missing at the Rossville site. All data from 2000 to 2008, excluding 2007, for each month was correlated. Again, the data was paired when both samplers collected data. The Rossville PM 2.5 FRM data was compared to the Siskin Drive PM 2.5 FRM data and the Maxwell Road/Tombras Avenue PM 2.5 FRM data to see the correlation between each month of missing 2007 data. Then, the data was grouped in a variation of seasonal months and a correlation was found for each season. That data is shown in the following table.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 13

Comparison of Rossville and Siskin Drive PM 2.5 FRM Data by Month and Season (2000-2008)
Month Correlation June 0.97814 July 0.96806 August 0.85492 September 0.76562 October 0.96313 November 0.91439 Season Correlation Summer (June-Aug) 0.93303 Summer (July-Sept) 0.85510 Fall (Sept-Nov) 0.87533 Fall (Oct-Nov) 0.91767

Comparison of Rossville and Maxwell

Road/Tombras Avenue PM 2.5 FRM Data by Month and Season (2000- 2008) Month Correlation June 0.94879 July 0.96761 August 0.86245 September 0.81186 October 0.98300 November 0.94227 Season Correlation Summer (June-Aug) 0.91599 Summer (July-Sept) 0.87001 Fall (Sept-Nov) 0.91387 Fall (Oct-Nov) 0.95158

Table 2: Comparison of PM 2.5 FRM Data for Month and Season of Missing Data

Comparing each month and season showed relatively high correlations across the months and seasons that the Rossville site did not collect data in 2007. When comparing the Rossville and Siskin Drive sites, the correlations ranged from 0.76562 in September to 0.97814 for June. Four out of 6 months are above the 0.9 regulation. For the Maxwell Road/Tombras Avenue and Rossville sites, the correlations ranged from 0.81186 in September to 0.98300 in October. Four out of 6 months are also above 0.9 for t he Rossville and Maxwell Road/Tombras Avenue monthly comparison. For all the monthly correla tions, the month of July showed to have the strongest relationship for Maxwell Road/Tombras Avenue and Siskin Drive compared with Rossville.

For the seasonal comparisons, the Rossville and Siskin Drive sites showed the strongest relationship during June through August (0.93303). The Rossville and Maxwell Road/Tombras Avenue sites showed the strongest relationship during October through November (0.95158).Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 14

Each quarter of PM 2.5 FRM data collected at the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites was correlated to determine compliance with Appendix N requirement that the data must yield a correlation coefficient of at least 0.9 for each calendar quarter. The following table shows a comparison of quarterly correlations between the Rossville and Siskin Drive sites, and between the Rossville and Maxwell Road/Tombras Avenue sites. The data was paired when both samplers collected data. The data compared in the following table was the PM 2.5 FRM data, including all available paired data points from 2000 to 2008 for comparing the Rossville site to Siskin Drive and Maxwell Road/Tombras Avenue sites.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 15

Quarterly Correlations of Rossville and Siskin Drive PM 2.5 FRM Data Quarterly Correlations of Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data Year-Quarter Correlation Year-Quarter Correlation 2000-1 0.97385 2000-1 0.95447 2000-2 0.92657 2000-2 0.85416 2000-3 0.88698 2000-3 0.92787 2000-4 0.92353 2000-4 0.98096 2001-1 0.94127 2001-1 0.97757 2001-2 0.97009 2001-2 0.97222 2001-3 0.96617 2001-3 0.98960 2001-4 0.91969 2001-4 0.94996 2002-1 0.86290 2002-1 0.98164 2002-2 0.75961 2002-2 0.95921 2002-3 0.97954 2002-3 0.98952 2002-4 0.83582 2002-4 0.81446 2003-1 0.93108 2003-1 0.36391 2003-2 0.99296 2003-2 0.99259 2003-3 0.95448 2003-3 0.95107 2003-4 0.95418 2003-4 0.95537 2004-1 0.86647 2004-1 0.80579 2004-2 0.93077 2004-2 0.89906 2004-3 0.96196 2004-3 0.96136 2004-4 0.93139 2004-4 0.83740 2005-1 0.98142 2005-1 0.72292 2005-2 0.97486 2005-2 0.94467 2005-3 0.99680 2005-3 0.96555 2005-4 0.92862 2005-4 0.89340 2006-1 0.91198 2006-1 0.97034 2006-2 0.93359 2006-2 0.88766 2006-3 0.98178 2006-3 0.99397 2006-4 0.91947 2006-4 0.96303 2007-1 0.93794 2007-1 0.92204 2007-2 0.99426 2007-2 0.98933 2007-4 0.97718 2007-4 0.98386 2008-1 0.81757 2008-1 0.74407 2008-2 0.91353 2008-2 0.90803 2008-3 0.57852 2008-3 0.60825 2008-4 0.93541 2008-4 0.95962

Table 3: Comparison of Quarterly Correlations

The majority of PM 2.5 FRM correlations are above the required 0.9 (highlighted in yellow). Of the 35 quarterly correlations calculated, 28 PM 2.5 FRM correlations were above 0.9 for the Rossville and Siskin Drive comparisons. There is a timeframe from the second quarter of 2004 through the fourth quarter of 2007 when all the correlations are greater than 0.9 for the Rossville and Siskin Drive sites. If the correlations were rounded from the second decimal place (above 0.85), there would be three more correlations at 0.9. For the available 2007 data used in theGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 16

correlations, all three quarters were above 0.9 for the Rossville and Siskin Drive site comparisons.

There were 24 PM 2.5 FRM quarterly correlations above 0.9 for the Rossville and Maxwell Road/Tombras Avenue comparison. If the correla tions were rounded from the second decimal place (above 0.85), there would be four more correlations at 0.9. For the available 2007 data used in the correlations, all three quarters were above 0.9 for the Rossville and Maxwell Road/Tombras Avenue site comparisons.

For both the 2008 quarterly comparisons of the Rossville site to the Siskin Drive and Maxwell Road/Tombras Avenue sites, the correlations were above 0.9 for the second and fourth quarters. There was a consistent pattern for both comparisons, in which the correlations dipped slightly below 0.9 for the first quarter of 2008. The Rossville and Siskin Drive sites showed a correlation of 0.81757. The Rossville and Maxwell Road/Tombras Avenue correlation was 0.74407. Then both correlations went above 0.9 for the second quarter. The Rossville and Siskin Drive sites showed a correlation of 0.91353. The Rossville and Maxwell Road/Tombras Avenue correlation was and 0.90803. For the third quarter, both correlations dipped further below 0.9. The Rossville and Siskin Drive sites showed a correlation of 0.57852. The Rossville and Maxwell Road/Tombras Avenue correlation was and 0.60825. Then again in the fourth quarter, both correlations went above 0.9, with the strongest correlations for 2008. The Rossville and Siskin Drive sites showed a correlation of 0.93541. The Rossville and Maxwell Road/Tombras Avenue correlation was and 0.95962.

2.2 Comparison of Means

In order to compare the PM 2.5 FRM annual means for the Rossville, Maxwell Road/ Tombras Avenue, and Siskin Drive sites, data was retrieved from AQS and percent differences of the annual means were derived. To compare the 2007 data equally across the sites during the timeframe that the Rossville site did not collect data, that year’s data was calculated manually. To be consistent for all sites, all of the individual 2007 samples collected were taken from AQS. The dates of 6/12/07 through 11/13/07 were excluded from all the sites. All the remaining data was used for the calculation, including data that may have been taken out of the dataset for regulatory purposes regarding exceptional events. Each quarter of 2007 data was averaged and then those quarterly averages were averaged together to calculate the 2007 annual mean. This procedure is derived from the 40CFR50
, Appendix N, part 4.4 Equations for the Annual PM 2.5 NAAQS. This is part of the process used in calculating the PM 2.5 FRM annual means to eventually compare to the PM 2.5 annual standard.

The first section of the table compares the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM annual means. The second section of the table compares the Rossville and Siskin Drive PM 2.5 FRM annual means. The resulting percent difference is shown for each year.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 17

Comparison of Annual Means ( μ g/m 3 )

Rossville Maxwell Road/ Tombras Avenue Percent Difference 2000 18.53 18.97 -2.32% 2001 15.55 16.65 -6.61% 2002 14.84 15.14 -1.98% 2003 16.00 16.46 -2.79% 2004 14.70 15.65 -6.07% 2005 16.55 16.06 3.05% 2006 14.45 14.26 1.33% 2007 14.24* 14.02* 1.57% 2008 12.48 12.29 1.55%

Rossville Siskin Drive Percent Difference 2000 18.53 17.40 6.49% 2001 15.55 16.19 -3.95% 2002 14.84 14.61 1.57% 2003 16.00 14.85 7.74% 2004 14.70 14.40 2.08% 2005 16.55 15.55 6.43% 2006 14.45 14.93 -3.22% 2007 14.24* 13.64* 4.40% 2008 12.48 12.80 -2.50% *calculated manually

Table 4: Comparison of Means

All of the percent differences between the PM 2.5 FRM annual means data for Rossville compared to Maxwell Road/Tombras Avenue and Si skin Drive sites showed differences less than 10%. As guidance, the 40CFR50
, Appendix N, paragraph (2.0) (B) (1) regulation was used. This regulation states that annual mean concentrations need to be less than 10% different when compared to the spatial average.

The PM 2.5 FRM annual means from the above table are shown in the following graphs. The first graph shows a comparison of the annual means for the Rossville and Maxwell Road/Tombras Avenue sites from 2000 to 2008. A comparison of the annual means from 2000 to 2008 for the Rossville and Siskin Drive sites is shown in the second graph. The Rossville site’s annual means are shown in blue in both graphs. All of the annual means were taken from AQS except the 2007 annual means. The 2007 data was calculated manually by extracting the individual values from AQS and calculating the annual mean as described above.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 18



### Rossville and Maxwell Road/Tombras Avenue PM 2.5 

### FRM
Annual Means

10 12 14 16 18 20

2000 2001 2002 2003 2004 2005 2006 2007 2008

YearAverage (ug/m3)

Rossville Maxwell Road/ Tombras Avenue

Figure 9: Comparison of PM 2.5 FRM Annual Means (Rossville and Maxwell Road/Tombras Ave)



### Rossville and Siskin Drive PM 2.5 

### FRM Annual Means

10 12 14 16 18 20

2000 2001 2002 2003 2004 2005 2006 2007 2008

YearAverage (ug/m3)

Rossville Siskin Drive

Figure 10: Comparison of PM 2.5 FRM Annual Means (Rossville and Siskin Drive)

Graphing the PM 2.5 FRM data helps to show the similarity of the Rossville site to the Maxwell Road/Tombras Avenue site and the Siskin Drive site. All three sites seem to show a comparable trend of annual means over the time span from 2000 to 2008. The Rossville, Maxwell Road/Tombras Avenue, and Siskin Drive sites all show higher annual means in 2000, with a drop until 2002. Then all three sites show an increase from 2002 to 2003 data, a drop from 2003 to 2004, an increase in 2005, and then a consistent drop through to the 2008 data.

In an effort to be thorough, PM 2.5 data (including FRM and speciation mass readings) were examined for differences in means. To compare t he entire dataset collected at each site, all the data was paired with the data from the other sampler on the days with the same sample date. IfGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 19

the data was given a null data code for a site for a sample date, or the dates did not match due to a make up sample, the data was taken out for both sites. All data with a pair of data points was used for calculations, including any data that may have been considered exceptional for regulatory purposes, and excluding data from June 12 through November 13, 2007 when the Rossville site was not sampling data



### . The data used in the analysis was extracted from AQS



### . Since the data was paired with data of the same date, and some data was removed due to not having a pair of data, a mean and percent difference was derived for this data. The following table shows the means for the complete dataset for each site after data was paired for the two sites, the percent difference of that paired data, and the dates of collected data used in each comparison. From dataset to dataset, the means could change due to the pairs of data changing with each comparison.

Comparison of Means ( μ g/m 3 ) with Each Pair of Data

Rossville PM 2.5 FRM Mean Siskin Drive PM 2.5 FRM Mean Percent Difference Dates* 14.83 14.47 2.50% 1/1/00 to 12/29/08

Rossville PM 2.5 FRM Mean Maxwell Road/Tombras Avenue PM 2.5 FRM Mean Percent Difference Dates* 14.96 14.93 0.20% 1/1/00 to 12/29/08 Rossville PM 2.5 Speciation Mass Mean Siskin Drive PM 2.5 FRM Mean Percent Difference Dates* 15.36 14.07 9.19% 3/23/05 to 3/26/09 Rossville PM 2.5 Speciation Mass Mean Siskin Drive PM 2.5 Speciation Mass Mean Percent Difference Dates* 15.85 16.44 -3.57% 3/23/05 to 12/26/08 Rossville PM 2.5 Speciation Mass Mean Maxwell Road/Tombras Avenue PM 2.5 FRM Mean Percent Difference Dates* 15.40 14.65 5.13% 3/23/05 to 12/26/08 *Excludes the missing data from 6/12/07 to 11/13/07

Table 5: Comparison of Means with Each Pair of Data

All of the means of the paired data comparisons between the Rossville and Siskin Drive sites were below the 10% used as guidance. Also, all of the means of the paired data comparisons between Rossville and Maxwell Road/Tombras Av enue sites were below the 10% used as guidance. The Rossville and Siskin Drive PM 2.5 FRM data comparison was from January 1, 2000 to December 29, 2008 and had a 2.50% difference, much lower than 10%. The Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data comparison was from January 1, 2000 to December 29, 2008 and had a 0.20% difference, also much lower than 10%. The Rossville PM 2.5 speciation mass and Siskin Drive PM 2.5 FRM data comparison March 23, 2005 to March 26, 2009 and had a 9.19% difference. The Rossville PM 2.5 speciation mass and Siskin Drive PM 2.5 speciation mass data comparison was from March 23, 2005 to December 26, 2008 and had a –3.57% difference. The Rossville PM 2.5 speciation mass and Maxwell Road/Tombras Avenue PM 2.5 FRM data comparison was from March 23, 2005 to December 26, 2008 and had a 5.13% difference. The ability of these paired comparisons to meet the rigorous requirements for spatial averaging (annual mean within 10 percent of spatially averaged annual mean) indicates a strong relationship between the sites.

2.3 Spatial Averaging

The purpose of this section is to use t he EPA’s guidance for spatial averaging, 40CFR50
, Appendix N, paragraph (2.0) (B) (1) as a tool for developing the weight of evidence forGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 20

determining attainment/nonattainment for the Chattanooga, TN-GA MSA. The annual means for the Rossville site were compared with the spatial average for each grouping of the Siskin Drive and Maxwell Road/Tombras Avenue sites. The guidance states, ‘ the annual mean concentration at each site shall be within 10 percent of the spatially averaged annual mean .’ To give different scenarios of spatially averaging the sites, every possibility of grouping the three sites was examined.

Three PM 2.5 FRM sites within the Chattanooga, TN-GA MSA (Rossville, Maxwell Road/ Tombras Avenue, and Siskin Drive) were used in the annual mean spatial averaging comparison to the Rossville site. All available years of PM 2.5 FRM data was used to determine spatial averages, and all data was extracted fr om AQS. To compare the 2007 data equally, data from June 12 through November 13 was taken out when calculating each of the sites’ annual means for 2007. Each quarter of 2007 data was averaged and then those quarterly averages were averaged to calculate the 2007 annual mean, as derived from 40CFR50
, Appendix N. This is part of the process used in calculating the PM 2.5 FRM annual means to eventually compare to the PM 2.5 annual standard. All data was used in the 2007 calculations, including any data that may have been taken out of the dataset for exceptional events. All of the other years’ annual means were taken directly from AQS, without any recalculating. To be thorough, every variation of grouping the three sites within the Chattanooga, TN-GA MSA was examined to compare spatial averages to each Rossville annual mean. All of the percent differences were well below the recommended 10%. Those calculations are shown in the tables below.

Table 6 shows the percent difference for the sp atially averaged annual means of the Rossville and Maxwell Road/Tombras Avenue sites compared to the annual mean of the Rossville site. Table 7 shows the percent difference for the sp atially averaged annual means of the Rossville and the Siskin Drive sites compared to the annual mean of the Rossville site. Table 8 shows the percent diff erence for the spatially averaged annual means of the Rossville, Maxwell Road/Tombras Avenue, and the Siskin Drive sites compared to the annual mean of the Rossville site.

Spatial Average of Rossville and Maxwell Road/Tombras Avenue ( μ g/m 3 ) Percent Difference between Rossville and Spatial Average

2000 18.75 -1.17% 2001 16.10 -3.42% 2002 14.99 -1.00% 2003 16.23 -1.42% 2004 15.18 -3.13% 2005 16.31 1.50% 2006 14.36 0.66% 2007 14.13* 0.78% 2008 12.39 0.77% *derived from manual calculation of mean

Table 6: Comparison of Annual Mean to Spatial Average (Rossville and Maxwell Road/Tombras Ave)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 21

Spatial Average of Rossville

and Siskin Drive ( μ g/m 3 ) Percent Difference between Rossville and Spatial Average

2000 17.97 3.15% 2001 15.87 -2.02% 2002 14.73 0.78% 2003 15.43 3.73% 2004 14.55 1.03% 2005 16.05 3.12% 2006 14.69 -1.63% 2007 13.94* 2.15% 2008 12.64 -1.27% *derived from manual calculation of mean

Table 7: Comparison of Annual Mean to Spatial Average (Rossville and Siskin Drive)

Spatial Average of Rossville, Maxwell Road/Tombras Avenue, and Siskin Drive ( μ g/m 3 ) Percent Difference between Rossville and Spatial Average

2000 18.30 1.26% 2001 16.13 -3.60% 2002 14.86 -0.16% 2003 15.77 1.46% 2004 14.92 -1.45% 2005 16.05 3.09% 2006 14.55 -0.66% 2007 13.97* 1.96% 2008 12.52 -0.35% *derived from manual calculation of mean

Table 8: Comparison of Annual Mean to Spatial Average (Rossville, Maxwell Road/Tombras Avenue, Siskin Drive)

To examine several possible spatial average calculations, three sites within the Chattanooga, TN-GA MSA were grouped several ways to make comparisons of the annual means. In Table 6, all of the pe rcent difference comparisons between the Rossville site and the spatial average of the Rossville and Maxwell Road/Tombras Avenue site s were very low, below +/-3.42%. This is well below the 10% guidance [40CFR50
, Appendix N, paragraph (2.0) (B) (1)]. Seven out of the nine years compared between Rossville and Maxw ell Road/Tombras Avenue sites’ spatial average and the Rossville site had percent differences less than +/-1.5%.

In Table 7, all of the percent difference comparisons between the Rossville site and the spatial average of the Rossville and Siskin Drive sites were also very low, below +/-3.73%. This again is well below the 10% guidance. Six out of the nine years compared between the Rossville and Siskin Drive sites’ spatial average and the Rossville site had percent differences less than +/- 2.15%.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 22

In Table 8, all of the percent difference comparisons between the Rossville site and the spatial average of the Rossville, Ma xwell Road/Tombras Av enue, and Siskin Drive sites were also very low, below +/-3.60%. Again, the percent differences are well below the 10% guidance. Seven out of the nine years compared between the Rossville, Maxwell Road/Tombras Avenue, and Siskin Drive sites’ spatial average and the Rossville site had percent differences less than +/- 1.96%. These low percent differences indicate that the data from Maxwell Road/Tombras Avenue, Siskin Drive, and Rossville all represent the same air mass.

2.4 Linear Regressions

As an additional way to show how well each dataset compared for the PM 2.5 data (including FRM and speciation mass readings), linear regressions and resulting R 2 values were examined. To compare the data collected at each site, all of the data was paired with the data from the other sampler on the days with the same sample date. If the data was given a null data code for a site for a sample date, or the dates did not match due to a make up sample, the data was taken out for both sites. All data with a pair of data points was used for calculations, including any data that may have been considered exceptional for regulatory purposes, and excluding data from June 12 through November 13, 2007 when the Rossville site was not sampling. All data was extracted from AQS. The following list shows the types of PM 2.5 data compared at each site and the dates of data compared.

All Possible Data Included Dates*

Rossville PM 2.5 FRM vs. Siskin Drive PM 2.5 FRM 1/1/00 to 12/29/08

Rossville PM 2.5 FRM vs. Maxwell Road/Tombras Avenue PM 2.5 FRM 1/1/00 to 12/29/08

Rossville PM 2.5 Speciation Mass vs. Siskin Drive PM 2.5 FRM 3/23/05 to 3/26/09

Rossville PM 2.5 Speciation Mass vs. Siskin Drive PM 2.5 Speciation Mass 3/23/05 to 12/26/08

Rossville PM 2.5 Speciation Mass vs. Maxwell Road PM 2.5 FRM 3/23/05 to 12/26/08 *Excludes the missing data from 6/12/07 to 11/13/07

Table 9: Dates Used in PM 2.5 Comparisons

The following graphs show the results of the linear regressions and resulting R 2 value for each pair of data listed above. Each linear regression was set with an intercept of zero and created using Excel. All concentrations are in micrograms per cubic meter ( μ g/m 3 ). Following the series of graphs is a summary table showing all the R 2 values for all of the datasets compared.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 23



### Rossville PM 2.5 

### FRM vs. Siskin Drive PM 2.5 

### FRM

y = 0.9697x
R 2 = 0.8386

0 10 20 30 40 50 60 70 80

0 1 0 2 0 3 0 4 0 5 0

Rossville PM 2.5 FRMSiskin Drive PM2.5FRM

Figure 11: Comparison of Rossville PM 2.5 FRM and Siskin Drive PM 2.5 FRM

Rossville vs. Maxwell Road/Tombras Avenue PM 2.5 FRM

y = 0.9839x
R 2 = 0.831

0 10 20 30 40 50 60 70

0 10 20 30 40 50

Rossville PM 2.5 FRMMaxwell Road/TombrasAvenue PM2.5FRM

Figure 12: Comparison of Rossville PM 2.5 FRM and Maxwell Road/Tombras Avenue PM 2.5 FRMGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 24



### Rossville PM 2.5 

### Speciation Mass vs. Siskin Drive PM 2.5 

### FRM

y = 1.067x
R 2 = 0.7962

0 10 20 30 40 50 60

0 10 20 30 40 50

Siskin Drive PM 2.5 FRMRossville PM2.5Speciation Mass

Figure 13: Comparison of Rossville PM 2.5 Speciation Mass and Siskin Drive PM 2.5 FRM



### Rossville PM 2.5 

### Speciation Mass vs. Siskin Drive PM 2.5 

### Speciation Mass

y = 0.9857x
R 2 = 0.6039

0 10 20 30 40 50 60

0 10 20 30 40 50 60

Rossville PM 2.5 Speciation MassSiskin Drive PM2.5Speciation Mass

Figure 14: Comparison of Rossville PM 2.5 Speciation Mass and Siskin Drive PM 2.5 Speciation MassGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 25



### Rossville PM 2.5 

### Speciation Mass vs. Maxwell

Road/Tombras Avenue PM 2.5 

### FRM

y = 1.0221x

R 2 = 0.7846

0 10 20 30 40 50 60

0 10 20 30 40 50 60

Maxwell Road/Tombras Avenue PM 2.5 FRMRossville PM2.5Speciation Mass

Figure 15: Comparison of Rossville PM 2.5 Speciation Mass to Maxwell Road/Tombras Avenue PM 2.5 FRM

The following table summarizes the R 2 values for all of the above linear regressions.

Sites Compared R 2

Rossville PM 2.5 FRM vs. Siskin Drive PM 2.5 FRM 0.8386

Rossville PM 2.5 FRM vs. Maxwell Road PM 2.5 FRM 0.8310

Rossville PM 2.5 Speciation Mass vs. Siskin Drive PM 2.5 FRM 0.7962

Rossville PM 2.5 Speciation Mass vs. Siskin PM 2.5 Speciation Mass 0.6039

Rossville PM 2.5 Speciation Mass vs. Maxwell Road PM 2.5 FRM 0.7846

Table 10: Summary of R 2 Values

The above linear regression graphs and table were produced using all available years of PM 2.5 data derived from AQS and omitting any unpair ed data. This unpaired data occurred when one site may have had data collected and the other site did not, or the dates did not match due to a make up sample, as well as the unpaired data from the June to November 2007 timeframe without Rossville data. The data used in the comparison included any data that may have been taken out for regulatory purposes with exceptional events. The comparisons were done on different types of PM 2.5 data (FRM and speciation mass) available at each site, and on three sites within the Chattanooga, TN-GA MSA with PM 2.5 FRM monitors.

With a comparison of all of the R 2 values derived from the linear regressions, the Rossville and Siskin Drive PM 2.5 FRM monitors show the strongest relationship, with 0.8386. This corresponds with the strongest relationship found when calculating the Pearson Product-Moment Correlation in this analysis. The Pearson Product-Moment Correlation between the Rossville and SiskinGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 26

Drive PM 2.5 FRM monitors was 0.91609. This linear regression was examining all paired PM 2.5 FRM data collected from January 1, 2000 to December 29, 2008.

To be consistent from site to site, all available data from AQS was used in the comparisons, including any data points that may have been considered exceptional events and taken out of the datasets for regulatory purposes. For example, the high data point of 71.6 μ g/m 3 shown in Figure 11, the comparison of all Rossville and Siskin Drive PM 2.5 FRM data, is a data point that was caused by an exceptional event. The sample was collected at the Siskin Drive site on November 2, 2000. On this same date, the Rossville PM 2.5 FRM sampler collected a sample of 48.7 μ g/m 3

. Both samples are high, however, this type of situation could be contributing to the slight difference in data and R 2 value of 0.8386. Even with this occasional difference in data, the linear regression between the Rossville and Siskin Drive PM 2.5 FRM data is relatively tight, with most data points following the regression line.

The next highest R 2 value was derived from the linear regression comparison between the Rossville and the Maxwell Road/Tombras Avenue PM 2.5 FRM monitors. The R 2 value was 0.8310. This also corresponds with the second highest Pearson Product-Moment Correlation for the comparison between the Rossville site and the Maxwell Road/Tombras Avenue site, which was 0.91362. In Figure 12, as discussed above, the high data point can be seen in the comparison of the Rossville an d Maxwell Road/Tombras Avenue PM 2.5 FRM data. On November 2, 2000 at the Rossville site, the value was 48.7 μ g/m 3 and at the Maxwell Road/Tombras Avenue site the value was 62.1 μ g/m 3 . This linear regression was comparing all paired PM 2.5 FRM data collected from January 1, 2000 to December 29, 2008. The majority of the data points between the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data follow the regression line, with few data points outside the line.

The remaining R 2 values ranged from 0.6039 to 0.7962. These R 2 values are relatively high overall. The lowest R 2 value of 0.6039 was calculated for the comparison of the Rossville and Siskin Drive speciation mass readings.

2.5 Descriptive Statistics and Box Plot

In order to further explore the comparison of PM 2.5 FRM data collected at the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites, box plots with descriptive statistics were examined. The Rossville and Siskin Drive PM 2.5 FRM data and the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data were plotted and analyzed using SigmaStat. These comparisons were made on the paired PM 2.5 FRM data between the Rossville and the Siskin Drive sites, and on the paired PM 2.5 FRM data between Rossville and the Maxwell Road/Tombras Avenue sites. The descriptive statistics and box plot were produced for both comparisons on the data from January 2000 to December 2008.

The first table shows the descriptive statistics between the Rossville site and the Siskin Drive site. The descriptive statistics include the standard deviation, standard error, confidence interval of mean, maximum value, minimum value, median value, 25% and 75%. The information pertaining to ‘Col 1’ is Rossville PM 2.5 FRM data and ‘Col 2’ is Siskin Drive PM 2.5 FRM data. The mean for the Rossville PM 2.5 FRM data was 14.831 μ g/m 3 , with standard deviation of 7.428
μ g/m 3 , standard error of 0.326 μ g/m 3 . The Rossville site’s maximum value was 48.7 μ g/m 3

, median value of 13.6 μ g/m 3 , 25% of 9.6 μ g/m 3 , and 75% of 18.3 μ g/m 3 . The mean for the Siskin Drive PM 2.5 FRM data was 14.469 μ g/m 3 , with standard deviation of 7.669 μ g/m 3 , standard error of 0.337 μ g/m 3 . The Siskin Drive site’s maximum value was 71.6 μ g/m 3 , median value of 13.1
μ g/m 3 , 25% of 9.2 μ g/m 3 , and 75% of 17.9 μ g/m 3 . All data from January 1, 2000 to DecemberGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 27

29, 2008 with a pair of data points was used for calculations, including any data that may have been considered exceptional for regulatory purposes, and excluding data from June 12 through November 13, 2007. There were a total of 518 paired data points between the Rossville and Siskin Drive PM 2.5 FRM monitors from January 1, 2000 to December 29, 2008. Data was extracted from AQS. In order to view this in formation more easily, a box plot of this same information is shown after the descriptive statistics on the Rossville and Siskin Drive PM 2.5 FRM data.



### Descriptive Statistics: Thursday, November 19, 2009, 3:57:53 PM

Data source: Data 1 in Notebook 1

Column Size Missing Mean Std Dev Std. Error C.I. of Mean Col 1 518 0 14.831 7.428 0.326 0.641 Col 2 518 0 14.469 7.669 0.337 0.662

ColumnRange Max Min Median 25% 75% Col 1 47.700 48.700 1.000 13.600 9.600 18.300 Col 2 69.900 71.600 1.700 13.100 9.200 17.900

ColumnSkewness Kurtosis K-S Dist . K-S Prob. Sum Sum of Squares Col 1 1.206 2.512 0.0926 <0.001 7682.400 142464.740 Col 2 1.794 7.292 0.0978 <0.001 7495.200 138858.980

Table 11: Descriptive Statistics of the Rossville and Siskin Drive PM 2.5 FRM Data from SigmaStat

The following box plot is an additional way of looking at the descriptive statistics listed above for the Rossville and Siskin Drive PM 2.5 FRM data. The top end of the box defines the 75 th percentile and the lower end of the box defines the 25 th percentiles. The line in the middle of the box is the median. The error bars define the 10 th and 90 th percentiles. Column 1 is Rossville PM 2.5 FRM data, and Column 2 is Siskin Drive PM 2.5 FRM data. The data shown in this way appears to be almost identical, with the exception of the maximum 71.6 μ g/m 3 data point at the Siskin Drive site. As discussed above, this data point was collected on November 2, 2000 and caused by an exceptional event. The maximum value at the Rossville site was 48.7 μ g/m 3 , also collected on November 2, 2000. The majority of data points for both sites appear to be between about 1 and 35 μ g/m 3

.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 28



### Box Plot of Rossville and Siskin Drive PM2.5 FRM Data

XData Column: 1 Column: 2Y Axis

0 20 40 60 80

Figure 16: Box Plot of Rossville and Siskin Drive PM 2.5 FRM Data Produced in SigmaStat

Using SigmaStat, a Mann-Whitney Rank Sum Tes t was performed on the Rossville and Siskin Drive PM 2.5 FRM data collected from January 1, 2000 to December 29, 2008. This test is used to determine if there is a greater difference between two groups than can be attributed to random sampling variation. The null hypothesis is that the two samples are not taken from sets of data with different medians. The results of the Mann-Whitney Rank Sum Test showed that the difference between median values is not statistically significant, with a P value of 0.266.

The following table shows the descriptive statistics between the Rossville site and the Maxwell Road/Tombras Avenue site. The descriptive statistics include the same as listed above. The information pertaining to ‘Col 2’ is Rossville PM 2.5 FRM data and ‘Col 3’ is Maxwell Road/Tombras Avenue PM 2.5 FRM data. The mean for the Rossville PM 2.5 FRM data wasGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 29

14.963 μ g/m 3 , with standard deviation of 7.538 μ g/m 3 , standard error of 0.342 μ g/m 3 . The maximum value was 48.7 μ g/m 3 , median value of 13.8 μ g/m 3 , 25% of 9.7 μ g/m 3 , and 75% of 18.9 μ g/m 3 . The mean for the Maxwell Road/Tombras Avenue PM 2.5 FRM data was 14.933
μ g/m 3 , with standard deviation of 7.660 μ g/m 3 , standard error of 0.347 μ g/m 3 . The maximum value was 62.1 μ g/m 3 , median value of 13.55 μ g/m 3 , 25% of 9.6 μ g/m 3 , and 75% of 18.2 μ g/m 3

. All data from January 1, 2000 to December 29, 2008 with a pair of data points was used for calculations, including any data that may have been considered exceptional for regulatory purposes, and excluding data from June 12 through November 13, 2007. There were a total of 486 paired data points between the Rossville and Siskin Drive PM 2.5 FRM monitors from January 1, 2000 to December 29, 2008. Data was extracted from AQS. In order to view this information more easily, a box plot of this same information is shown after the descriptive statistics on the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data.



### Descriptive Statistics: Tuesday, January 26, 2010, 7:09:51 AM

Data source: Data 1 in MaxwellRdStats.SNB

Column Size Missing Mean Std Dev Std. Error C.I. of Mean Col 2 486 0 14.963 7.538 0.342 0.672 Col 3 486 0 14.933 7.660 0.347 0.683

ColumnRange Max Min Median 25% 75% Col 2 47.700 48.700 1.000 13.800 9.700 18.900 Col 3 60.600 62.100 1.500 13.550 9.600 18.200

ColumnSkewness Kurtosis K-S Dist . K-S Prob. Sum Sum of Squares Col 2 1.186 2.423 0.0921 <0.001 7272.200 136376.620 Col 3 1.649 5.362 0.0974 <0.001 7257.300 136831.590

Table 12: Descriptive Statistics of the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data from SigmaStat

The box plot below is an additional way of looking at the descriptive statistics listed above for the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data. The top end of the box defines the 75 th percentile and the lower end of the box defines the 25 th percentiles. The line in the middle of the box is the median. The error bars define the 10 th and 90 th percentiles. Column 2 is Rossville PM 2.5 FRM data, and Column 3 is Maxwell Road/Tombras Avenue PM 2.5 FRM data. The data shown in this way appears to be almost identical, with the exception of the maximum 62.1 μ g/m 3 data point at the Maxwell Road/Tombras Avenue site. As discussed above, this data point was collected on November 2, 2000 and caused by an exceptional event. The maximum value at the Rossville site was 48.7 μ g/m 3 , also collected on November 2, 2000. The majority of data points for both sites appear to be between about 1 and 35 μ g/m 3

.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 30



### XData Column: 2 Column: 3Y Axis

0 10 20 30 40 50 60 70 

### Box Plot of Rossville and Maxwell Road/Tombras Avenue PM2.5 FRM Data

Figure 17: Box Plot Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data Produced in SigmaStat

A Mann-Whitney Rank Sum Test was also performed on the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data collected from January 1, 2000 to December 29, 2008 using SigmaStat. The null hypothesis is that the two samples are not taken from sets of data with different medians. The results of the Mann-Whitney Rank Sum Test showed that the difference between the median values is not statistically significant, with a P value of 0.821.

In both box plots in Figure 16 and Figure 17, the PM 2.5 FRM data from 2000 to 2008 for the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites have very similar distribution. In both box plots, the three sites appear to have the same ‘normal’, or 25 th to 75 th percentile range of data. With all three sites, this appears to be around 10 to 20 μ g/m 3 . The 10 th percentileGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 31

is around 8 μ g/m 3 and the 90 th percentile is around 25 μ g/m 3 . Further, most of the data that is outlying this 10 th and 90 th percentile is grouped primarily in the same areas. The majority of the outlying data points fall close to the 10 th and 90 th percentile ranges and gradually spread out from those percentiles. There are a couple of higher data points at the Siskin Drive and Maxwell Road/Tombras Avenue sites as discussed above. However, overall the PM 2.5 FRM data at all three sites appear to have almost identical distribution. In addition, both comparisons of the Rossville site to Siskin Drive and Maxwell Road/Tombras Avenue sites showed that the differences between the medians were not statistically significant.

2.6 Comparison of Source

As a guidan ce tool for analyzing the PM 2.5 data at the Rossville site and the other sites within the Chattanooga, TN-GA MSA, Appendix N was used. It states that, ‘ 2.0, b (3) All of the monitoring sites should principally be affected by the same major emission sources of PM 2.5 . For example, this could be demonstrated by site-specific chemical speciation profiles confirming all major component concentration averages to be within 10 percent for each calendar quarter.’ Since the Rossville and Siskin Drive sites showed one of the strongest relationships and both sites collect PM 2.5 speciation data, more analyses were performed on the PM 2.5 speciation data. Pearson Product-Moment Correlations, R 2 values with linear regressions, quarterly percent differences, quarterly absolute differences, and quarterly percent contributions were examined on select PM 2.5 speciation data. For the Pearson Product-Moment Correlations, Appendix N was followed as a guideline. This section of Appendix N suggests that the daily values for each site pair have a correlation coefficient of at least 0.9 for each calendar quarter. In addition, a source apportionment model, Positive Matrix Factorization (PMF), was performed on the PM 2.5 speciation data. With each analysis, the procedures and results are discussed below.

The timeframe for comparison for the Pearson Product-Moment Correlations, R 2 values with linear regressions, quarterly percent differences, quarterly absolute differences, and quarterly percent contributions was April 4, 2005 through December 26, 2008, excluding the June 12 through November 13, 2007 dates when the Rossville site was not collecting data. The PM 2.5 speciation samplers collect samples on a one in six day sampling schedule, and collect over 50 different PM 2.5 species in the samples. Since there were only two data points collected for the first quarter of 2005, in March, the first quarter of 2005 was not examined. For the percent differences, absolute differences, and percent contributions, each quarter was examined separately with the same dates as above.

2.6.1 Correlations of PM 2.5 Speciation Data

The following table shows the Pearson Product-Moment Correlations on select PM 2.5 speciation data for all of the data collected from April 4, 2005 through December 26, 2008, excluding the June 12 through November 13, 2007 data. The PM 2.5 species were selected for their common occurrence in PM 2.5 speciation samples. The PM 2.5 species evaluated were organic carbon, elemental carbon, sulfate, ammonium ion, to tal nitrate, aluminum, silicon, and potassium. The aluminum and silicon species are part of the crustal group.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 32

Pearson Product-Moment

Correlations of Select Speciation Data at Rossville and Siskin Drive Species Correlation Organic Carbon 0.86413 Elemental Carbon 0.76752 Sulfate 0.98717
Ammonium Ion 0.94559
Total Nitrate 0.92864
Aluminum 0.81740 Silicon 0.94792
Potassium 0.94013

Table 13: Correlations of Select Speciation Data between Rossville and Siskin Drive Sites

Table 13 shows the Pearson Product-moment Correlations for the select PM 2.5 speciation data at the Rossville and Siskin Drive sites across the approximately three years of data, from 2005 to 2008. For the select speciation data comparison, the sulfate correlation showed a very strong relationship between the two sets of data, with a Pearson Product-Moment Correlation of 0.98717. This high correlation of sulfate could indicate the both the Rossville and Siskin Drive sites are affected by common sulfate sources. All of the species examined showed a strong relationship, with high Pearson Product-Moment Correlations. Five out of eight correlations were above 0.9 (highlighted in yellow). The lowest correlation was elemental carbon, with 0.76752.

2.6.2 Scatter Plots and R 2 Values of PM 2.5 Speciation Data

A scatter plot and corresponding R 2 value were produced on the PM 2.5 speciation data collected at the Rossville and Siskin Drive sites. The following graphs show the information for the same PM 2.5 species as listed above. These PM 2.5 species include organic carbon, elemental carbon, sulfate, ammonium ion, total nitrate, alumi num, silicon, and potassium. Following the graphs is a summary table of the R 2 values produced from the linear regressions.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 33



### Organic Carbon

y = 0.9975x
R 2 = 0.7347

0 5 10 15 20

0 2 4 6 8 10 12 14

Siskin DriveRossville

Figure 18: Select PM 2.5 Speciation Data Scatter Plots (Organic Carbon)



### Elemental Carbon

y = 0.784x
R 2 = 0.5333

0 0.5

1 1.5

2 2.5

0 0.5 1 1.5 2 2.5 3

Siskin DriveRossville

Figure 19: Select PM 2.5 Speciation Data Scatter Plots (Elemental Carbon)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 34



### Sulfate

y = 0.9679x
R 2 = 0.9744

0 2 4 6 8 10 12 14 16 18

0 2 4 6 8 10 12 14 16 18

Siskin DriveRossville

Figure 20: Select PM 2.5 Speciation Data Scatter Plots (Sulfate)



### Ammonium Ion

y = 0.8991x
R 2 = 0.892

0 1 2 3 4 5

0123456

Siskin DriveRossville

Figure 21: Select PM 2.5 Speciation Data Scatter Plots (Ammonium Ion)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 35



### Total Nitrate

y = 0.7858x
R 2 = 0.8621

0 1 2 3 4 5 6 7

01234567

Siskin DriveRossville

Figure 22: Select PM 2.5 Speciation Data Scatter Plots (Total Nitrate)



### Aluminum

y = 0.9662x
R 2 = 0.6674

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

Siskin DriveRossville

Figure 23: Select PM 2.5 Speciation Data Scatter Plots (Aluminum)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 36



### Silicon

y = 0.9039x
R 2 = 0.898

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8

Siskin DriveRossville

Figure 24: Select PM 2.5 Speciation Data Scatter Plots (Silicon)



### Potassium

y = 1.4926x
R 2 = 0.8496

0 0.5

1 1.5

2 2.5

0 0.2 0.4 0.6 0.8 1 1.2

Siskin DriveRossville

Figure 25: Select PM 2.5 Speciation Data Scatter Plots (Potassium)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 37

R 2 Values of Select Speciation Data at Rossville and Siskin Drive (2005-2008) Organic Carbon 0.7347 Elemental Carbon 0.5333 Sulfate 0.9744 Ammonium Ion 0.8920 Total Nitrate 0.8621 Aluminum 0.6674 Silicon 0.8980 Potassium 0.8496

Table 14: Summary of Speciation R 2 Values

Of the select PM 2.5 species examined between the Rossville and Siskin Drive sites, the R 2 value between sulfate concentrations corresponds with the highest Pearson Product-Moment Correlation and shows a very high R 2 value, 0.9744. Almost all the data pairs of sulfate concentrations are on the line of regression. The high R 2 value between the sulfate data at the Rossville site and the Siskin Drive site could indicate a common source of sulfate affecting both sties. Ammonium ion, total nitrate, silicon, and potassium also show a strong relationship between the paired data and have R 2 values above 0.8. This is particularly true of total nitrate, which is usually considered a volatile species. For total nitrate to have a high R 2 value, this indicates that the Rossville and Siskin Drive sites share the same air mass.

The sulfate concentrations have one of the highest concentrations of the PM 2.5 species examined for both the Rossville and Siskin Drive sites. The sulfate concentrations were as high as 16.5 μ g/m 3 for the paired data, and the R 2 value was 0.9744. The higher concentrations of sulfate could be attributing the stronger R 2 value. The lowest R 2 value of 0.5333 was with the elemental carbon data. With the paired data of elemental carbon, the highest concentration was only 2.79 μ g/m 3 . The majority of the elemental carbon data points were below 1 μ g/m 3 . For the aluminum linear regression, the R 2 value was 0.6674. The highest concentration of the paired aluminum data was even lower, with 0.612 μ g/m 3

. The majority of the data points were below 0.1 μ g/m 3

. The remaining PM 2.5 species examined have R 2 values between 0.7347 and 0.8980 for the Rossville and Siskin Drive data. Organic carbon’s highest concentration of paired data was 18.1
μ g/m 3 . The R 2 value of organic carbon was 0.7347. The majority of the paired organic carbon data points were between 1 μ g/m 3 and 10 μ g/m 3 . The highest concentration of paired ammonium ion data was 5.06 μ g/m 3 . The R 2 value of the linear regression for ammonium ion was 0.8920. The majority of the paired ammonium ion data points were between 0.3 μ g/m 3 and 3 μ g/m 3 . Total nitrate’s highest concentration of paired data was 6.59 μ g/m 3 . The R 2 value of total nitrate linear regression was 0.8621. The majority of the paired total nitrate data points were between 0.1 μ g/m 3 and 2 μ g/m 3 . The highest concentration of paired silicon data was 1.66
μ g/m 3 . The R 2 value of silicon data linear regression was 0.8980. The majority of the paired silicon data points were between 0 μ g/m 3 and 0.2 μ g/m 3 . Potassium’s highest concentration of paired data points was 2.15 μ g/m 3 . The R 2 value of the linear regression for potassium data was 0.8496. The majority of the paired potassium data points were between 0 μ g/m 3 and 0.2 μ g/m 3

.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 38

2.6.3 Percent Differences of PM 2.5 Speciation Data

In order to examine the PM 2.5 speciation data further, percent differences were compared for each quarter that the speciation data could be paired. The following table shows the results of the quarterly percent differences. The select PM 2.5 species evaluated were organic carbon, elemental carbon, sulfate, ammonium ion, total nitrate, aluminum, silicon, and potassium. Percent differences were derived for all of the data collected from April 4, 2005 through December 26, 2008, excluding the June 12 through November 13, 2007 data. In order to be consistent, if there was not a pair of data for both the Rossville and Siskin Drive sites for a sample day, the data point was taken out of the dataset. The calculations were made using Excel, with the equation: (Rossville value-Siskin Drive value)/Siskin Drive value. The resulting percent differences (shown in the table below) showed some variation, depending on PM 2.5 species and number of samples to compare per quarter. With the majority of the quarterly percent difference comparisons, the Rossville site had a lower value than the Siskin Drive site. Those percent differences are shown as a negative number.

Percent Difference of Select Speciation Data at Rossville and Siskin Drive (%)
YearQuarter Organic Carbon Elemental Carbon Sulfate Ammonium Ion Total Nitrate Aluminum Silicon Potassium

2005-1 No Data to Compare
2005-2 1.58 -26.38 0.43 -16.26 -35.55 209.27 -2.95 10.74
2005-3 -0.64 -3.49 -3.82 -18.73 -24.49 86.37 43.84 18.79
2005-4 -3.36 -14.67 -5.04 -19.97 -27.90 -51.89 -29.99 6.82
2006-1 8.01 -19.98 1.41 0.46 -14.68 -24.08 -29.95 0.92
2006-2 3.77 -22.95 -3.02 2.52 -31.63 -3.12 -0.95 3.71
2006-3 -4.32 -19.01 -3.28 -2.75 -28.75 -14.34 -14.07 67.44
2006-4 8.96 3.90 -4.43 7.82 -10.96 -35.61 -15.16 8.39
2007-1 -5.65 -3.61 -4.63 -11.60 -22.95 -7.77 -16.75 -0.47
2007-2 -5.40 -15.69 -3.14 -3.72 -9.35 -23.78 -9.16 -10.85
2007-3 No Data to Compare
2007-4 30.78 -27.65 -1.96 -8.45 -23.42 53.31 -13.39 -4.98
2008-1 -1.24 -0.22 -12.87 -21.59 -30.28 -26.92 -23.51 -4.14
2008-2 2.88 -28.49 -9.69 -9.84 -16.97 -3.34 3.13 0.92
2008-3 -3.65 -29.81 -0.70 -1.02 -31.65 -30.72 -0.85 -10.22
2008-4 5.55 -14.23 -6.25 -11.42 -20.65 20.19 0.69 20.79

Table 15: Quarterly Percent Differences of Select Speciation Data between Rossville and Siskin Drive Sites

The percent differences for sulfate (highlighted in yellow) were consistently the lowest across all the quarters examined for the Rossville and Siski n Drive sites. Thirteen of the 14 quarters compared were below the +/-10% used as guidance. The percent differences ranged from 0.43% to -12.87%. The first quarter of 2008 had a –12.87% difference between the Rossville and Siskin Drive sites. There were fewer samples to compare the first quarter of 2008, with a total of 9 paired data points in that quarter. This could be attributing to the slightly higher percent difference. If all samples were collected and compared between the two sites, there would be approximately 15 samples to compare. In addition, there was one sample collected, on January 1, 2008 in which the Rossville site’s concentration was 0.879 μ g/m 3 and the Siskin Drive site’s concentration was 4.46 μ g/m 3 . If these data points were removed and the percent differenceGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 39

recalculated, the difference would be 0.04% for the first quarter of 2008. Almost all of the percent differences were consistently well below +/-10%. The lower percent differences could indicate that both the Rossville and Siskin Drive sites are affected by common sulfate sources. Sulfate concentrations were as high as 16.5 μ g/m 3 for the paired data. The percent differences are also shown in the graph below to help view the data. The sulfate percent differences are shown in red.

The organic carbon percent differences are almost all below +/-10% as well. Thirteen of the 14 quarters examined were below +/-10%. The only quarter that was above +/-10% was the fourth quarter of 2007, where there were only 6 data points to compare. The resulting percent difference was 30.78%. For a normal sampling quarter, there would be approximately 15 data points to compare. Of those 6 data points to compare, there was one data point that Siskin Drive sampled 9.64 μ g/m 3 and Rossville sampled 18.1 μ g/m 3 . If that data point were not part of the dataset, and the percent difference were re-examined, there would be a 9.30% difference for that quarter. Along with sulfate, organic carbon consistently had low percent differences, excluding the fourth quarter of 2007. This could also indicate common sources of organic carbon at both the Rossville and Siskin Drive sites.

More than half of the potassium quarterly percent differences are below +/-10%, with the lowest value of –0.47%. In the third quarter of 2006, there were only 8 samples to compare between the Rossville and Siskin Drive sites. Of the 8 values to compare, one data pair consisted of 0.987 μ g/m 3 for Siskin Drive and 2.15 μ g/m 3 for the Rossville site, on July 4, 2006. The resulting percent difference for the third quarter of 2006 was 67.44%. Potassium is often associated with fireworks. It is possible that the higher potassium level at the Rossville site on July 4, 2006 was a local source of fireworks.

Overall, about half of the quarters of the select PM 2.5 species compared had percent differences below the +/-10% used in Appendix N. In some cases, the sample values collected were very low, and when there is a slight difference in the low numbers, it results in a large percent difference. This can be seen with the aluminum percent differences. Most of the aluminum samples collected are in the 0.0005 to 0.6 μ g/m 3 range, with several samples shown as 0
μ g/m 3 . As one example, there was a difference of –35.61% for the fourth quarter of 2006 for aluminum. The two paired dataset’s averages for that quarter were 0.025641 μ g/m 3 for the Siskin Drive site and 0.016509 μ g/m 3 for the Rossville site. This was only a difference of 0.009
μ g/m 3 between the Rossville and Siskin Drive sites’ aluminum data for that quarter. As another example, for the second quarter of 2005, the paired averages were 0.0021 μ g/m 3 for the Siskin Drive site and 0.0065 μ g/m 3 for the Rossville site. This was only a difference of 0.0044 μ g/m 3

. Of the comparable aluminum data points for the second quarter of 2005, there was only one value detected above 0 μ g/m 3 at the Siskin Drive site and six data points detected above 0 μ g/m 3 at the Rossville site. This difference caused a 209.27% difference for the second quarter of 2005. This is the only quarter with such a large percent difference. The large difference could be attributed to the very low and 0 μ g/m 3 concentrations and the limited number of samples to compare between the two sites.

The remaining four species (elemental carbon, ammonium ion, total nitrate and silicon) showed some variation in their percent differences between the Rossville and Siskin Drive data. Elemental carbon had four quarters out of fourteen with percent differences below +/-10%. There were eight quarters out of fourteen that were below +/-10% difference for ammonium ion. Total nitrate had one quarter below +/-10% difference. There were six quarters that were below +/-10% difference for silicon. In general, the elemental carbon and total nitrate species have higher spatial gradients. This spatial variability could be attributing to the quarters with theGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 40

higher percent differences between the Rossville and Siskin Drive data. In addition, all four of these species are measured at low concentrations, similar to aluminum discussed above. Both the elemental carbon and total nitrate species ar e primarily measured at concentrations below 1
μ g/m 3 . Ammonium ion is predominantly m easured at concentrations below 2 μ g/m 3 . Silicon is measured at even lower concentrations, primarily below 0.2 μ g/m 3 . A small difference between two low concentrations can result in a large percent difference.

The results of the percent differences showed variations, depending on the PM 2.5 species, number of samples to compare per quarter, and the amount of concentration detected. In some cases, when there were more samples to compare, such as sulfate and organic carbon, the percent differences were lower. Also, in most cases with higher sample concentrations, such as sulfate and organic carbon, the percent differences were lower.

The following graph shows quarterly percent differences for the select species of PM 2.5 displayed in the table above. The minimum and maximum percent difference were limited to +/- 30% in order to view the species with the least quarterly percent differences more closely. The percent differences are shown for each quarter from the second quarter of 2005 through the fourth quarter of 2008, excluding the third quarter of 2007.



### Quarterly Percent Differences of Select PM 2.5 

### Speciation Data, 2005-2008

-30 -20 -10

0 10 20 30

QuarterPercent Difference

Organic Carbon Elemental Carbon Sulfate Ammonium Ion
Total Nitrate Aluminum Silicon Potassium

Figure 26: Quarterly PM 2.5 Speciation Percent Differences for Rossville and Siskin Drive Sites

The above graph shows the quarterly percent differences for the select species of PM 2.5 data examined at the Rossville and Siskin Drive sites, as shown in the table above. In order to show the species with the least amount of percent difference, the maximum and minimum limit was cut off at +/-30%. It is evident that sulfate (shown in red) shows the least amount of percent difference between the Rossville and Siskin Drive sites. Ammonium ion (shown in green) and elemental carbon (shown in pink) also consistently have percent differences that are below +/-Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 41

30%. Organic carbon (shown in dark blue) and potassium (shown in lighter shade of blue) have only one data point that is outside the +/-30% range.

Since a few of the PM 2.5 species showed higher percent differences, especially when the sampled concentrations were very low, a comparison was made of the absolute differences between the Rossville and Siskin Drive sites’ PM 2.5 speciation data. With the following table, those absolute values of the differences in concentrations are shown for the same quarterly data as shown in Table 15 above.

Quarterly Absolute Differences of Select Speciation Data at Rossville and Siskin Drive

YearQuarter Organic Carbon Elemental Carbon Sulfate Ammonium Ion Total Nitrate Aluminum Silicon Potassium

2005-1 No Data to Compare 2005-2 0.076154 0.159077 0.027333 0.348800 0.321067 0.004423 0.001540 0.006440 2005-3 0.034286 0.018843 0.294286 0.427929 0.114786 0.029206 0.045921 0.020793 2005-4 0.175625 0.132813 0.191125 0.298000 0.305313 0.013183 0.025463 0.004881 2006-1 0.326000 0.137733 0.045333 0.006600 0.207400 0.002567 0.022047 0.000587 2006-2 0.189167 0.126175 0.155000 0.042833 0.191167 0.001043 0.001458 0.002300 2006-3 0.247500 0.105375 0.193750 0.049375 0.143625 0.016093 0.057763 0.140863 2006-4 0.438125 0.032819 0.128500 0.089375 0.151125 0.009132 0.007126 0.004884 2007-1 0.326667 0.026651 0.141933 0.170600 0.406400 0.001893 0.011751 0.000300 2007-2 0.258333 0.100833 0.155000 0.067417 0.065083 0.008243 0.009408 0.005358 2007-3 No Data to Compare 2007-4 1.806667 0.325667 0.073750 0.173375 0.486125 0.003981 0.006729 0.004050 2008-1 0.041000 0.001100 0.396778 0.302556 0.437889 0.005021 0.014113 0.001963 2008-2 0.140000 0.142714 0.417333 0.143333 0.080467 0.001388 0.003840 0.000533 2008-3 0.189286 0.202857 0.040769 0.018385 0.119077 0.018041 0.000807 0.006129 2008-4 0.260000 0.105643 0.165357 0.142429 0.266500 0.001855 0.000289 0.010621

Table 16: Quarterly Absolute Differences of Select PM 2.5 Speciation Data between Rossville and Siskin Drive Sites

The above absolute differences between the quarterly PM 2.5 speciation data at the Rossville and Siskin Drive sites can be compared with the quarterly percent differences shown in Table 15. Almost all of the absolute differen ces between the select species are well below 0.5. As discussed above, it can be seen that with the occurrences of larger percent differences, there were small absolute value differences. The largest percent difference in Table 15 was a comparison of aluminum for the second quarter of 2005, which resulted in a 209.27% difference. As shown in the table above, the absolute difference for that quarter was 0.004423. This is a very low difference in quarterly averages. Of the comparable aluminum data points for the second quarter of 2005, there was only one value detected above 0 μ g/m 3 at the Siskin Drive site and six data points detected above 0 μ g/m 3 at the Rossville site.

The following graph displays the quarterly absolute differences for the select species of PM 2.5 shown in the above table. The absolute differences are shown for each quarter from the second quarter of 2005 through the fourth quarter of 2008, excluding the third quarter of 2007.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 42



### Quarterly Absolute Differences of Select PM 2.5 

### Speciation Data,
2005-2008

0.000000 0.200000 0.400000 0.600000 0.800000 1.000000 1.200000 1.400000 1.600000 1.800000 2.000000

2 0 0 5

- 2
2 0 0 5

- 3
2 0 0 5

- 4
2 0 0 6

- 1 2 0 0 6

- 2
2 0 0 6

- 3
2 0 0 6

- 4
2 0 0 7

- 1 2 0 0 7

- 2
2 0 0 7

- 4
2 0 0 8

- 1 2 0 0 8

- 2
2 0 0 8

- 3
2 0 0 8

- 4

QuarterAbsolute Difference

Organic Carbon Elemental Carbon Sulfate Ammonium Ion
Total Nitrate Aluminum Silicon Potassium

Figure 27: Quarterly PM 2.5 Speciation Absolute Differences for Rossville and Siskin Drive Sites

The above graph shows the quarterly absolute differences for the select species of PM 2.5 data examined at the Rossville and Siskin Drive sites, as shown in the table above. It is evident that all of the species analyzed had very low absolute quarterly differences. The majority of the absolute differences were between 0 and 0.486125. The absolute difference of 0.486125 was for total nitrate, for the fourth quarter of 2007.

There was one absolute difference that was above this range of values (0 to 0.486125) for the Rossville and Siskin Drive sites. With the absolute differences of organic carbon, there was a value of 1.806667 for the fourth quarter of 2007. The quarterly averages were 7.676667 μ g/m 3 for the Rossville site and 5.87 μ g/m 3 for the Siskin Drive site for that quarter.

2.6.4 Percent Contribution of PM 2.5 Speciation Data

The PM 2.5 speciation data was also examined to determine the percent contribution of each species to the total speciation mass data collected for both the Rossville and Siskin Drive sites. Organic carbon, elemental carbon, sulfate, ammoni um ion, total nitrate, aluminum, silicon and potassium were examined. As a first examination of the PM 2.5 speciation data, each select PM 2.5 species was compared independently of the other site. The data was not paired between the Rossville and Siskin Drive sites. A contribution of each PM 2.5 species was calculated as part of the whole PM 2.5 speciation mass sample for each site independently of the other site’s data. A quarterly average of each select PM 2.5 species was calculated, and a quarterly average of the PM 2.5 speciation mass was calculated. Then each PM 2.5 species was calculated as part of the PM 2.5 speciation mass reading to determine the percent contribution of that PM 2.5 species to the total PM 2.5 speciation mass reading. The following tables summarize that data. The first table shows the percent contribution of the PM 2.5 speciation data at the Rossville site. The second table shows the percent contribution of the PM 2.5 speciation data at the Siskin Drive site.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 43

Percent Contribution of Select Speciation Data at Rossville (%)

YearQuarte r Organic Carbon Elemental Carbon Sulfate Ammonium Ion Total Nitrate Aluminum Silicon Potassium

2005-1 No Data to Compare 2005-2 28.75 2.60 37.30 10.53 3.41 0.04 0.30 0.39 2005-3 25.81 2.54 36.46 9.11 1.74 0.29 0.73 0.62 2005-4 35.41 5.42 25.27 8.38 5.54 0.09 0.42 0.54 2006-1 34.33 4.31 25.52 11.31 9.42 0.06 0.40 0.51 2006-2 29.73 2.56 28.13 9.73 2.38 0.17 0.83 0.37 2006-3 23.73 2.43 28.50 8.42 1.58 0.31 1.09 1.07 2006-4 34.83 5.72 18.13 8.06 8.03 0.11 0.26 0.41 2007-1 37.34 4.87 19.98 8.89 9.33 0.15 0.40 0.43 2007-2 30.59 3.66 32.32 11.81 4.27 0.18 0.63 0.30 2007-3 No Data to Compare 2007-4 38.48 4.27 18.46 9.41 7.97 0.06 0.22 0.39 2008-1 33.48 2.08 22.84 10.62 11.31 0.12 0.38 0.45 2008-2 33.77 2.42 26.30 8.88 2.66 0.27 0.86 0.40 2008-3 29.66 2.77 33.14 10.18 1.50 0.25 0.57 0.32 2008-4 39.18 5.16 19.52 8.60 7.62 0.10 0.32 0.50

Table 17: Percent Contribution of Select Speciation Data for Rossville

Percent Contribution of Select Speciation Data at Siskin Drive (%)

YearQuarte r Organic Carbon Elemental Carbon Sulfate Ammonium Ion Total Nitrate Aluminum Silicon Potassium

2005-1 No Data to Compare 2005-2 26.98 3.27 33.70 11.16 4.08 0.01 0.27 0.30 2005-3 24.39 2.47 35.28 10.47 2.15 0.15 0.48 0.51 2005-4 28.62 4.96 20.79 8.18 6.00 0.14 0.47 0.39 2006-1 31.03 5.26 24.56 10.99 10.77 0.08 0.56 0.49 2006-2 28.83 3.06 28.68 9.45 3.38 0.20 0.91 0.39 2006-3 28.84 2.79 29.79 9.06 2.52 0.57 2.07 1.05 2006-4 34.59 5.95 20.53 8.09 9.76 0.18 0.33 0.41 2007-1 36.36 4.64 19.25 9.24 11.13 0.15 0.44 0.40 2007-2 27.45 3.36 28.35 10.15 3.37 0.20 0.60 0.30 2007-3 No Data to Compare 2007-4 33.26 6.33 22.13 12.08 12.23 0.04 0.30 0.48 2008-1 31.44 4.71 25.14 11.23 11.61 0.18 0.53 0.44 2008-2 31.37 3.32 28.78 9.73 3.17 0.28 0.82 0.39 2008-3 29.39 3.66 31.41 9.73 2.29 0.34 0.58 0.42 2008-4 39.78 6.30 21.89 10.40 10.24 0.07 0.36 0.44

Table 18: Percent Contribution of Select Speciation Data for Siskin Drive

Of the select species, sulfate and organic carbon are the largest contributors to the overall speciation mass for both the Rossville and Siskin Drive sites. Both sites seem to follow theGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 44

same trend of percent contribution through the period of sampling data, particularly for these two species, organic carbon and sulfate. For most quarters of data, when one site is in the 20% range, for organic carbon, the other site is as well. Then when the percent changes to the 30% contribution range for one site, the other site changes also. The same for sulfate, when one site is in the 20% range, or changes to 30% range, the other site does also. For example, for Rossville in 2008, organic carbon had 33.48% contribution for the first quarter, 33.77% for the second quarter, dropped down to 29.66% for the third quarter, and back up to 39.18% contribution for the fourth quarter. For the Siskin Drive site, in 2008 organic carbon had 31.44% contribution for the first quarter, 31.37% for the second quarter, then dropped down to 29.39% in the third quarter, and back up to 39.78% contribution in the fourth quarter. Both sites followed the same pattern of decreasing the percent contribution from second to third quarter, and then increasing again in the fourth quarter.

As another example, for Rossville in 2008, sulfate had 22.84% contribution for the first quarter, 26.30% for second, went up to 33.14% for third, and back down to 19.52% contribution for fourth quarter. For the Siskin Drive site, in 2008 sulfate had 25.14% contribution for the first quarter, 28.78% for the second quarter, then went up to 31.41% in the third quarter, and back down to 21.89% contribution in the fourth quarter. Both sites followed the same pattern of increasing the percent contribution from the second to third quarter, and then decreasing again in the fourth quarter.

For most of the species of PM 2.5 data, both the Rossville and Siskin Drive sites show the greatest amount and least amount of contribution during the same quarters of compared data. For aluminum, silicon, and potassium, the largest percentage is found the third quarter of 2006 for both sites. For organic carbon, the largest percentage is found the fourth quarter of 2008 for both sites. For sulfate, both sites show the largest percentage in the third quarter of 2005. Several species also show the lowest percentage for the same quarter for both the Rossville and Siskin Drive sites. Organic carbon shows the lowest contributing percentage for both sites for the third quarter of 2005. Ammonium ion has the least amount of percentage for the fourth quarter of 2006 for both sites. Total nitrate shows the least amount of percentage for the third quarter of 2008 for both sites. Aluminum has the lowest amount of contributing percentage the second quarter of 2005 for both the Rossville and Siskin Drive sites. Potassium shows the least amount of percentage for the Rossville site, and one of two least amount percentages for the Siskin Drive site for the second quarter of 2007.

With both the Rossville and Siskin Drive sites showing similar percent contributions and consistent patterns of greatest and least amount of contribution for the select PM 2.5 speciation data, it appears that both sites are influenced by the same sources. As can be seen in the above tables, one of the major contributors for both the Rossville and Siskin Drive sites was sulfate. Of the fourteen calendar quarters examined, thirteen quarters were within 10 percent difference for sulfate. One quarter was slightly outside the range with a percent difference of – 12.77%.

In addition to examining the percent contributions of the PM 2.5 speciation data independently at each the Rossville and Siskin Drive sites, the PM 2.5 speciation data was also paired. The data was calculated with pairs in an effort to be consistent with the other comparisons in this document, as well to perform an equal comparison of the data. Each of the PM 2.5 species was paired when both the Rossville and Siskin Drive sites collected data. Then each of the PM 2.5 species was paired with the PM 2.5 speciation mass readings. A percent contribution was calculated for each quarter when the pairs of PM 2.5 species matched the pairs of PM 2.5 speciation mass readings. This process was performed in an effort to ensure the percentGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 45

contributions were a true reflection of the whole average for the quarter. Those results are shown in the tables below. The first table shows the percent contribution of the PM 2.5 speciation data at the Rossville site. The second table shows the percent contribution of the PM 2.5 speciation data at the Siskin Drive site.

Percent Contribution of Paired Select Speciation Data at Rossville (%)
YearQuarter Organic Carbon Elemental Carbon Sulfate Ammonium Ion Total Nitrate Aluminum Silicon Potassium

2005-1 No Data to Compare 2005-2 28.44 2.57 37.30 10.53 3.41 0.04 0.30 0.39 2005-3 25.84 2.55 36.18 9.08 1.73 0.31 0.74 0.64 2005-4 35.41 5.42 25.27 8.38 5.54 0.09 0.42 0.54 2006-1 34.33 4.31 25.52 11.31 9.42 0.06 0.40 0.51 2006-2 29.04 2.36 27.79 9.72 2.30 0.18 0.85 0.36 2006-3 23.70 1.94 24.74 7.57 1.54 0.42 1.53 1.51 2006-4 34.83 5.72 18.13 8.06 8.03 0.11 0.26 0.41 2007-1 37.34 4.87 19.98 8.89 9.33 0.15 0.40 0.43 2007-2 30.59 3.66 32.32 11.81 4.27 0.18 0.63 0.30 2007-3 No Data to Compare 2007-4 33.87 3.76 18.46 9.41 7.97 0.06 0.22 0.39 2008-1 31.40 4.69 25.34 11.01 10.34 0.14 0.46 0.45 2008-2 33.29 2.39 26.30 8.88 2.66 0.27 0.86 0.40 2008-3 28.90 2.76 33.06 10.14 1.46 0.24 0.55 0.31 2008-4 39.26 5.06 19.72 8.78 8.14 0.09 0.34 0.49

Figure 28: Percent Contribution of Paired PM 2.5 Speciation Data at Rossville

Percent Contribution of Paired Select Speciation Data at Siskin Drive (%)
YearQuarter Organic Carbon Elemental Carbon Sulfate Ammonium Ion Total Nitrate Aluminum Silicon Potassium

2005-1 No Data to Compare 2005-2 25.72 3.21 34.27 11.61 4.89 0.01 0.28 0.32 2005-3 24.39 2.47 35.28 10.47 2.15 0.15 0.48 0.51 2005-4 28.62 4.96 20.79 8.18 6.00 0.14 0.47 0.39 2006-1 31.03 5.26 24.56 10.99 10.77 0.08 0.56 0.49 2006-2 28.28 3.10 28.95 9.58 3.41 0.19 0.87 0.35 2006-3 28.84 2.79 29.79 9.06 2.52 0.57 2.07 1.05 2006-4 34.59 5.95 20.53 8.09 9.76 0.18 0.33 0.41 2007-1 36.36 4.64 19.25 9.24 11.13 0.15 0.44 0.40 2007-2 27.05 3.63 27.91 10.26 3.94 0.20 0.58 0.28 2007-3 No Data to Compare 2007-4 31.53 6.33 22.13 12.08 12.23 0.04 0.30 0.48 2008-1 29.87 4.61 27.11 13.30 14.01 0.17 0.54 0.42 2008-2 32.43 3.35 28.78 9.73 3.17 0.28 0.82 0.39 2008-3 28.66 3.76 32.26 10.25 2.07 0.32 0.53 0.33 2008-4 39.84 6.32 22.53 10.61 10.98 0.08 0.36 0.43

Figure 29: Percent Contribution of Paired PM 2.5 Speciation Data at Siskin DriveGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 46

In comparing the PM 2.5 speciation data produced with the percent contributions calculated independently and the percent contributions calculated with the paired data, there were only minor changes to the data. There was some variation from species to species when one sampler had collected data and the other sampler had not (for instance, a make up sample), or when one sampler had a null data code and the other sampler collected data. If the particular PM 2.5 species had data collected, but there was not a PM 2.5 speciation mass sample for that day, the pair was taken out the calculation also. There were some quarters of data that were not affected by this additional calculation. For these quarters, the data was collected on every sample day, with no make up sample days, and there were no null data codes for the quarter. The second quarter of 2005 had very little or no change to the data. The third and fourth quarters of 2005 and first quarter of 2006 had no change. The third quarter of 2006 had almost no change. The fourth quarter of 2006 and first quarter of 2007 data had no change. The second quarter of 2007 had almost no changes.

One example of a change to the data was in the first quarter of 2008. There were two to three pairs of data taken out of the dataset in the first quarter of 2008, depending on the PM 2.5 species. The organic carbon at Rossville decreased from 33.48% to 31.40%. The elemental carbon increased from 2.08% to 4.69%. The sulfate decreased from 22.84% to 25.34%. There was an increase of 10.62% to 11.01% for ammonium ion. The total nitrate decreased from 11.31% to 10.34%. The aluminum increased from 0.12% to 0.14%. There was an increase of 0.38% to 0.46% for silicon. The potassium remained 0.45%. At the Siskin Drive site, the organic carbon decreased from 31.44 to 29.87%. There was a decrease from 4.71% to 4.61% for elemental carbon. The sulfate increased from 25.14% to 27.11%. The ammonium ion increased from 11.23% to 13.30%. The total nitrate increased from 11.23% to 14.01%. The aluminum decreased from 0.18% to 0.17%. There was an increase of 0.53% to 0.54% for silicon. The potassium decreased from 0.44% to 0.42%. Depending on the species percent contribution overall, the changes to the data was minor. For the species with the larger contributions, the changes were within 2 to 3%. For the species with the smaller contributions, the changes were within 0.01 to 0.1% different. The overall percent contributions remained the same. Organic carbon and sulfate remained the largest contributors to the overall PM 2.5 speciation data. Aluminum, silicon, and potassium remained the lowest contributors to the overall PM 2.5 speciation data.

2.6.5 Sources of PM 2.5 Speciation Data

In order to thoroughly analyze the Rossville PM 2.5 data for comparison to other sites in the Chattanooga, TN-GA MSA, an analysis was conducted to determine if the sites were affected by the same major emission sources of PM 2.5

. In addition to analyzing the Pearson ProductMoment correlations, linear regressions, R 2 values, percent differences, absolute differences, and percent contributions of select PM 2.5 speciation data, an analysis of sources of PM 2.5 was conducted.

The Rossville site is located in Walker County, Georgia, within the Chattanooga, TN-GA MSA. According to the Georgia 2008 Emissions Inventory, there are no major sources of PM 2.5 in Walker County, Georgia. However, there is a Title V Source in Walker County, Georgia that is a major source for sulfur dioxide (SO 2 ), with minimal particulate matter (PM) emissions. The SO 2 emissions are 273 tons per year from an industrial coal-fired boiler. This boiler also has particulate matter emissions of 6 tons per year. The facility is located at 34.883333/-85.300000, which is approximately 5.8 miles south of the Rossville-Health Center location and approximately 6.6 miles south of the Rossville-Maple Street location.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 47

The Siskin Drive and Maxwell Road/Tombras Avenue sites are located in Hamilton County, Tennessee, also within the Chattanooga, TN-GA MSA. In the Hamilton County area, there is one large source of PM 2.5 . This facility’s PM 2.5 emissions are 52.191 tons per year. It is located 9.75 miles from the Rossville site. The second largest PM 2.5 source has 14.55 tons per year. It is located 5.75 miles from the Rossville site. The largest source of PM 2.5 is also the largest source of SO 2 with 828.45 tons per year. The second largest source of PM 2.5 is also the second largest source of SO 2 , with 349 tons per year source of SO 2 . The next largest source of SO 2 is 31.19 tons per year. All other direct sources of PM 2.5 have emissions of less than 5 tons per year.

The density of population and that population’s characteristics can have a role in source emissions for that area. The 2008 population estimate for Walker County, GA is 64,799. For Hamilton County, TN, the 2008 population estimate is 332,848. The majority of the Chattanooga, TN-GA MSA’s population is in Hamilton County, TN. With the higher population in Hamilton County, TN, it is reasonable that the amount of PM 2.5 or SO 2 produced would be greater in the Hamilton County, TN area than in the Walker County, GA area. The largest source of SO 2 in Hamilton County, TN was 828.45 tons per year, and in Walker County, GA was 273 tons per year. The largest source of PM in Hamilton County, TN was 52.191 tons per year, and in Walker County, GA was 6 tons per year.

As can be seen in the section above, sulfate and organic carbon were the largest contributors to the PM 2.5 speciation data at both the Rossville and Siskin Drive sites. Organic carbon and sulfate also showed the lowest amount of percent difference between the quarterly averages of paired data from 2005 to 2008. The Pearson Product-Moment Correlation, linear regression, and R 2 values showed the strongest relationship between the sulfate species at the Rossville and Siskin Drive sites. The Pearson Product-Moment Correlation was 0.98717, and the R 2 value was 0.9744 for sulfate. To explore the sources further and determine if the largest contributors (sulfate and organic carbon) were attributed to similar sources, a source apportionment analysis was done on the PM 2.5 speciation data at the Rossville and Siskin Drive sites.

To perform the source apportionment analysis, a Positive Matrix Factorization (PMF) 3.0 model released by the United States Environmental Pr otection Agency's (US EPA) Office of Research and Development (ORD) was used. The PMF is a receptor model used to perform source apportionment analysis to identify and quantify contributions of different emission sources. The ambient observations of aerosol species and/or gas species concentrations and uncertainties at certain locations are used as PMF model inputs to calculate the number of sources, types, profiles, relative contributions, and a time series of contributions. The uncertainty is determined based on the measurement limits provided by EPA.

In this analysis, more than 30 chemical species have been collected from 2005 to 2008 at Siskin Drive, TN and Rossville, GA. Species with few missing data and high signal-to-noise ratios (S/N) were used for PMF analysis. In the test ru ns, some species were found to have more than 50% of their variances not to be explained by the PMF model. These species were discarded as well. Finally, 23 aerosol species were chosen for this analysis. Seven runs were conducted at each site with factor numbers from 6 to 12. The 8-factors run is finally chosen with a reasonable residual (Q robust). The 8 factors are identified to be from 8 different emission sources according to the spectrum of dominant species, as well as subjective judgment.

The first graph and table displays the Rossville PMF analysis data. For the graph, each of the eight factors (from eight sources) is displayed with the percentages for each factor shown as a bar. The eight factors for the Rossville site were secondary sulfate, soil dust, carbon-rich sulfate, smelting, textile manufacturing, bio/waste burning, copper industry, and zinc industry, shown inGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 48

that order. In the table that follows the graph, each source is given a percentage attributed to that source, the ranking of that source, whether or not it was found more often on a weekday or weekend day, the high season, and the low season.

• Rossville (2005-2008)

Figure 30: PMF Analysis Results of Speciated Fine Aerosol (PM 2.5 ) Observations from 2005 to 2008 at Rossville, GAGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 49

Factor Name Percentage Ranking WDWE High Season Low Season 1 2 nd sulfate 38.3 1 WD ~ WE Summer Winter 2 Soil dust 8.7 5 WD ~ WE Summer Winter 3 C-rich sulfate 11.4 3 WD ~ WE Summer Winter 4 Smelting 6.1 6 WD >> WE Summer Winter 5 Textile Manufacturing 11.4 3 WD ~ WE Summer Winter 6 Bio/waste burning 8.5 7 WD < WE Fall Spring 7 Cu industry 13.7 2 WD ~ WE Winter Summer 8 Zn industry 1.8 8 WD > WE Fall Summer

WDWE: Weekday and weekend

Table 19: PMF Analyzed Factors at Rossville, GA

The second graph and table displays the PMF analysis for the Siskin Drive site PM 2.5 speciation data. Each of the eight factors, from eight sources, is displayed with the percentages for each factor shown as a bar. The eight factors for the Siskin Drive site were textile manufacturing, copper industry, bio/waste burning, diesel, soil dust, smelting, secondary sulfate, and zinc industry, shown in that order. In the table that follow the graph, as in the preceding table, each source is given a percentage attributed to that source, the ranking of that source, whether or not it was found more often on a weekday or weekend day, the high season, and the low season.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 50

• Siskin Drive (2005-2008)

Figure 31: PMF Analysis Results of Speciated Fine Aerosol (PM 2.5 ) Observations from 2005 to 2008 at Siskin Drive, TN

Factor Name Percentage Ranking WDWE High Season Low Season 1 Textile Manufacturing 17.4 2 WD ~ WE Summer Fall 2 Cu industry 11.3 4 WD > WE Spring Summer 3 Bio/waste burning 13.9 3 WD < WE Fall Spring 4 Diesel 9.2 5 WD > WE Summer Spring 5 Soil dust 3.8 7 WD ~ WE Summer Winter 6 Smelting 4.2 6 WD >> WE Fall Winter 7 2 nd sulfate 37.2 1 WD ~ WE Summer Winter 8 Zn industry 3.0 8 WD >> WE Fall Summer

WDWE: Weekday and weekend

Table 20: PMF Analyzed Factors at Siskin Drive, TN (2005-2008)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 51

In the last table, a comparison is made between the percentages attributed to each of the factors, or sources.

• Comparison

Rossville, GA Siskin Drive, TN Factor Name (2005-2008) (2005-2008) 1 2 nd sulfate (1) 38.3 1,2 (1) 37.2 2 Cu industry (2) 13.7 (4) 11.3 3 Carbon-rich sulfate (3) 11.4 4 Textile Manufacturing (4) 11.4 (2) 17.4 5 Soil dust (5) 8.7 (7) 3.8 6 Smelting (6) 8.5 (6) 4.2 7 Bio/waste burning (7) 6.1 (3) 13.4 8 Zn industry (8) 1.8 (8) 3.0 9 Diesel (5) 9.2

Note 1: The percentages are listed after the ranking number in brackets. Note 2: Factors with >10% contributions are highlighted in yellow.

Table 21: Comparison of the Percentages Contributions of PMF Factors

To summarize, secondary sulfate is the largest component at both sites, contributing approximately 40% mass to the total PM 2.5 . Copper industry and textile manufacture contribute >10% at both sites from 2005 to 2008. Some small factors, such as soil dust, smelting, bio/waste burning, and Zn industry are identified at both sites. Diesel emission is found at theSiskin Drive site in Tennessee, but not at the Rossville site in Georgia. The secondary carbonrich sulfate is only found at the Rossville, GA site with 11% contributions.

As shown in Table 19 and Table 20 both the secondary sulfate datasets found at the Rossville site and the Siskin Drive site have similarities. For both sites, the secondary sulfate is found similarly during the week as on the weekend. Also, both sites show the high season to be in the summer and the low season to be in the winter.

As examined in the above PM 2.5 speciation sections, sulfate showed a very strong relationship between the Rossville site and Siskin Drive site data. With the analysis of the select PM 2.5 speciation data, the Pearson Product-Moment Correlation of the overall dataset from 2005 to 2008, the Pearson Product-Moment Correlations of the quarterly values, the linear regression and R 2 value of the overall dataset, and the quarterly percent differences all consistently showed sulfate to have a very strong relationship between the data collected at the Rossville and Siskin Drives sites. In addition, the source apportionment model shows that sulfate is the largest component contributing to the total PM 2.5 collected at the Rossville (38.3%) and Siskin Drive (37.2%) sites. These analyses were performed to verify that the PM 2.5 data meets the Appendix N regulation used as guidance for this document. Both the Rossville and Siskin Drive sites are principally affected by sulfate source s. For thirteen out of the available fourteen calendar quarters from 2005 to 2008, the sulfate data was within 10 percent difference for the Rossville and Siskin Drive sites. One quarter was slightly outside the range with a percent difference of –12.77%.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 52

2.7 Meteorological Summary for Rossville, GA and Hamilton County, TN

To show that an alternative data substitution method for incomplete data more accurately reflects the PM 2.5 air quality in the Chattanooga, TN-GA MSA than the EPA’s Guideline on Data Handling Conventions for the PM NAAQS, a number of statistical analyses have been conducted. However, as meteorology is an important factor in PM air quality, an analysis of the meteorology on the quarters of substituted data is required. The timeframe of incomplete data at the Rossville site was from June 12 to November 13, 2007. With the purpose of comparing the meteorological data for the third and fourth quarters, a few data points from the historical data were examined. In addition, the general meteorological conditions in the Walker County, Georgia and Hamilton County, Tennessee areas were evaluated.

The city of Rossville in Walker County, Georgia has a comparable meteorological regime to neighboring Hamilton County, Tennessee due to similar topography, geographic location and generally concurrent synoptic and meso-synoptic conditions. Typical temporal scales for mesosynoptic or sub-synoptic features are on the order of a few days to one week. Specific meteorological parameters, such as wind speed, wind direction, and relative humidity, among others, have shown in past studies to have a direct correlation with fine particulate matter (PM 2.5 ) concentrations. The observed corresponding relationship then between the PM 2.5 trends at the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites may be partially attributed to this shared meteorology.

As provided in previous summaries concerning transport in the Rossville area, Northwest Georgia resides in the Ridge-and-Valley Appalachians, which is a province of the larger Appalachian Mountains. This particular region is characterized by long, even ridges with long continuous valleys in between. Chattanooga, TN and the city of Rossville, GA both reside in the valley between the East Ridge and the western foothills of the Appalachians. The direction and speed of wind can be greatly affected by this topography. Valley areas like those in Northwest GA can be affected by terrain-related wind regimes such as pressure-driven channeling and forced channeling. These wind regimes, along with more large-scale synoptic patterns (i.e. High pressure, low-pressure systems) can impact the boundary layer concentrations of PM 2.5

.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 53

Figure 32: Map of Terrain Between Sites

In the recorded nine-year time frame (2000-2008), PM 2.5 24-hr readings at the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites showed several dates with like, if not exact, correlation in their values. These similarities were most often accompanied by shared meteorological conditions. In one such case, Oct. 30 th , 2004, both Rossville and Siskin Drive sites measured a 24-hr averaged value of 22.9 μ g/m 3 and Maxwell Road/Tombras Avenue averaged 23.2 μ g/m 3 under the influence of a weakening surface to upper level ridge positioned over the southeast. Surface analysis at 12Z on the 30 th indicated several haze reports across GA and TN in advance of an upper level low over Canada and trailing cold front. The 12z BNA (Nashville) and FFC (Peachtree City) soundings show ed dry midlevel flow at the leading edge of the front, with increasing low level southwesterly flow, which allowed for an increase in low level moisture as the day progressed. A similar case of prefrontal pooling of PM 2.5 occurred on June 2, 2007. On this particular case, the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites recorded elevated 24-hr averaged readings of 29.8 μ g/m 3

, 30.7 μ g/m 3 , and 31.2

μ g/m 3

, respectively. A third case of PM 2.5 consistency between sites, under similar meteorological conditions, was observed on May 30, 2008. An upper level ridge dominated the eastern U.S., with boundary layer winds indicating a light southerly component. Rossville recorded a 24-hr averaged reading of 25.8 μg/m 3 , Siskin Drive recorded a concentration of 26.7 μg/m 3 , and Maxwell Road/Tombras Avenue recorded a concentration of 25.6 μg/m 3

. Meteorologically speaking, the above cases all showed that all three sites were under similarGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 54

wind flow exposure, based on nearby surface and upper air observations during the same time period.

It is probable that continued case-by-case analy sis for various time periods would show good positive correlation in meteorological conditions and PM 2.5 readings between sites. A comparison of monthly wind direction (using RAWS data) for the third and fourth quarters of 2007 (July-Dec) showed good agreement in closely located GA and TN sites for all months except August.

Month Armuchee (GA) Prentice Cooper (TN) July 230 230 August 278 74 September 105 132 October 120 133 November 256 279 December 180 190

Table 22: Monthly Vector Averaged Wind Direction (Degrees)

The lone discrepancy noted in August could likely be attributed to more calms or variable winds recorded for that month, relative to the other months, since it was the peak of summer with the predominance of the Atlantic/Bermuda High. Surface winds tend to be calm, and/or light and variable under this condition, which can lead to erroneous reporting of wind direction. It should be mentioned that isolated convection during the summer months, as well as local boundary layer or micro-meteorological effects, can also lead to differences, however, overall daily averages between surface and upper air meteorological parameters should be quite similar between the Rossville and Siskin Drive sites on a me so-synoptic or sub-synoptic time scale. There could be local low-level wind flow variations between the Rossville and Maxwell Road/Tombras Avenue sites due to the sites being separated by the East Ridge (see Figure 32 above). However, the overall synoptic scale conditions should be similar for all three sites. Also noteworthy is that although the distance between Armuchee and Prentice Cooper State Forest and Wildlife Management Area is roughly 70 miles, and the elevation differs by about 750 ft, there is still good agreement in wind direction between these two sites. Therefore, one would expect even better agreement between the Rossv ille site and the Siskin Drive and Maxwell Road/Tombras Avenue sites, since they are only approximately 5 miles and 3.5 miles apart, respectively and differ by only 30 ft in elevation for both sites. In summary, based on meteorological analysis and observed similarities between surface and upper air observations, it is believed that either site could be used to represent the other with regard to PM 2.5 concentrations.

2.8 Comparison of All Rossville and Siskin Drive PM 2.5 FRM Data

The Rossville PM 2.5 FRM monitor showed the strongest relationship with the Siskin Drive and Maxwell Road/Tombras Avenue PM 2.5 FRM monitors. As an additional analysis, each of the paired data points between the Rossville and Siskin Drive PM 2.5 FRM monitors and between the Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM monitors were graphed for the total duration of comparison to see how well the data points compare. Because the datasets are large, the data was broken into three graphs, each showing three years of data, to be able to see more detail.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 55

The first three graphs are the comparison of the Rossville PM 2.5 FRM monitor and the Siskin Drive PM 2.5 FRM monitor. The Rossville PM 2.5 FRM data is shown in blue and the Siskin Drive PM 2.5 FRM data is shown in yellow.



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Figure 33: Comparison of All Rossville and Siskin Drive PM 2.5 FRM Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2000-2002)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 56



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Figure 34: Comparison of All Rossville and Siskin Drive PM 2.5 FRM Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2003-2005)



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1 /5/2 0 08

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1 1/5

/2

00

8

DateConcentration (ug/m3)

Rossville Siskin Drive

Figure 35: Comparison of All Rossville and Siskin Drive PM 2.5 FRM Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2006-2008)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 57

The Rossville PM 2.5 FRM monitor began sampling on January 1, 2000 with a one in six day schedule. On January 3, 2007, the Rossville site’s sampling schedule changed to one in three day schedule. The Siskin Drive PM 2.5 FRM monitor has run on a one in three day sampling schedule during the whole timeframe from January 2000. For this analysis, the data was paired when both monitors took a sample. Therefore, the paired data was on a one in six day schedule until January of 2007 when the Rossville site’s frequency changed to one in three day sampling. In the above graphs, the sampling frequency of paired data in shown to increase in Figure 35, with the 200 7 data. There was a total of 518 data points paired between the two sites over the nine year time span.

For most of the data points, it appears that the PM 2.5 FRM data from the Rossville site seems to track the PM 2.5 FRM data of the Siskin Drive site. There are some minor differences, but overall it appears that the data follows the same pattern. In Figure 33, there is a spike in the data for both site s on January 1, 2000. The Siskin Drive site shows a PM 2.5 concentration of 41.7 μ g/m 3 and the Rossville site reports 43.1 μ g/m 3 . Both sites have concentrations remaining around 10
μ g/m 3 to 30 μ g/m 3 following the same fluctuation until October 27, 2000 when both sites spike. The Rossville site collected a concentration of 48.3 μ g/m 3 while the Siskin Drive site collected 48.6 μ g/m 3 . Then on November 2, 2000 both sites continue to spike. The Siskin Drive site reports a PM 2.5 concentration of 71.6 μ g/m 3 and the Rossville site reports 48.7 μ g/m 3 . This is the maximum value for both sites over the whole nine years of data, as shown previously in Table 7, Descriptive Statistics. Again the same pattern is followed for both the Rossville and Siskin Drive sites through 2001. Both the Rossville and Siskin Drive sites show a low value on January 31, 2001. The Rossville site reports a concentration of 3.3 μ g/m 3 and the Siskin Drive site reports 5
μ g/m 3 . There is a smaller spike on November 15, 2001, with Rossville reporting a concentration of 34 μ g/m 3 and Siskin Drive reporting 47.5 μ g/m 3 . There is an obvious pattern from May 8, 2002 until October 17, 2002, in Figure 33, where both sites show almost the exact same PM 2.5 values. When one site’s concentration increased, the other site also increased. When one site’s concentration decreased, the other site also decreased. This timeframe is shown in the following table for ease of viewing. All values are in micrograms per cubic meter ( μ g/m 3 ).Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 58

Date Rossville Siskin Drive
5/8/2002 18.9 19.7
5/14/2002 8.9 8
5/26/2002 17.4 16.4
6/1/2002 23.5 21.3
6/7/2002 10.7 10
6/13/2002 21.8 22.1
6/25/2002 15.1 15.7
7/7/2002 27.7 28.4
7/13/2002 22.2 22
7/19/2002 9.9 9
7/25/2002 27.7 24.9
8/6/2002 25 27
8/12/2002 31.6 29.5
8/18/2002 8.5 7.3
8/30/2002 12.5 11.8
9/11/2002 32 28.9
9/17/2002 21.7 23.6
9/23/2002 19.5 18.9
9/29/2002 16 16.1
10/11/2002 17.5 17.5
10/17/2002 9 8.6

Table 23: Example of Rossville and Siskin Drive PM 2.5 FRM Data Trend

This pattern continues in 2003. In Figure 34, on March 9, 2003, the Siskin Drive site showed a low PM 2.5 concentration of 3.9 μ g/m 3 and the Rossville site also showed a low 2.9 μ g/m 3 . Then on March 15, 2003, the Siskin Drive site spikes to 31 μ g/m 3 while the Rossville site spikes to 30.7 μ g/m 3 . With the next pair of data, on March 21, 2003 both sites collected 10.1 μ g/m 3 . On June 26, 2003 both sites show a spike in the data. The Rossville site samples a PM 2.5 concentration of 46.9 μ g/m 3 and the Siskin Drive site samples 41.4 μ g/m 3 . Then on July 2, 2003, both sites dip down to PM 2.5 concentrations of 3 μ g/m 3

. Another example of the similarity in the PM 2.5 FRM data is shown in Figure 34, with the 2005 data. On Au gust 8, 2005, the Rossville site collected a PM 2.5 concentration of 8.2 μ g/m 3 , and the Siskin Drive site collected 8 μ g/m 3 . On August 14, 2005 both sites had a slight increase in concentration. The Rossville site sampled a PM 2.5 concentration of 20.9 μ g/m 3 and the Siskin Drive site sampled 20.1 μ g/m 3 . Both sites’ concentrations remained relatively steady on August 20, 2005. The Rossville sampled a PM 2.5 concentration of 16.9 μ g/m 3 and Siskin Drive sampled 18.3 μ g/m 3 . Then on August 26, 2005 both sites showed a spike in concentration. The Rossville site sampled 32.6 μ g/m 3 while the Siskin Drive site sampled 33.4 μ g/m 3 . There was a decrease in concentration on September 7, 2005 at both sites. The Rossville site sampled 16.5 μ g/m 3 and the Siskin Drive site sampled 15.9 μ g/m 3 . Then on September 13, 2005, both site’s concentrations spiked up again. The Rossville site collected a PM 2.5 concentration of 36.1 μ g/m 3 and the Siskin Drive site collected 36.3 μ g/m 3

.

In Figure 35, there is another example of both sites showing the same fluctuating pattern with almost ident ical data. On May 21, 2007 the Rossville site sampled a PM 2.5 concentration of 13.5
μ g/m 3 while the Siskin Drive site sampled 13.8 μ g/m 3 . On May 24, 2007 the Rossville siteGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 59

sampled 14.8 μ g/m 3 and the Siskin Drive site sampled 14.4 μ g/m 3 . Then on May 27, 2007 both sites spiked. Rossville sampled a PM 2.5 concentration of 43.9 μ g/m 3 and Siskin Drive site sampled 43.2 μ g/m 3 . On May 30, both sites sampled lower concentrations. The Rossville site collected 21.6 μ g/m 3 and the Siskin Drive site collected 22.3 μ g/m 3 . On June 2, 2007 both sites showed slightly higher concentrations. Rossville sampled 29.8 μ g/m 3 and Siskin Drive sampled 30.7 μ g/m 3 . Then on June 5, 2007, both sites showed even more of a drop in concentration. The Rossville site collected 9.3 μ g/m 3 while the Siskin Drive site collected 8.2 μ g/m 3

. The next three graphs display the comparison of the Rossville PM 2.5 FRM monitor and the Maxwell Road/Tombras Avenue PM 2.5 FRM monitor. Again, all of the data from 2000 to 2008 is examined. The data is broken down into three graphs to be able to see more detail in the comparison of data. The Rossville PM 2.5 FRM data is shown in blue and the Maxwell Road/Tombras Avenue PM 2.5 FRM data is shown in red.



## Rossville and Maxwell Road/Tombras Avenue 2000-2002

0 10 20 30 40 50 60 70

1 / 1 / 2 0 0 0

3 / 1 / 2 0 0 0

5 / 1 / 2 0 0 0

7 / 1 / 2 0 0 0

9 / 1 / 2 0 0 0

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1 1 / 1 / 2 0 0 2

DateConcentration (ug/m3)

Maxwell Rd/Tombras Ave
Rossville

Figure 36: Comparison of All Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2000-2002)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 60



## Rossville and Maxwell Road/Tombras Avenue 2003-2005

0 5 10 15 20 25 30 35 40 45 50

1 / 3 / 2 0 0 3

3 / 3 / 2 0 0 3

5 / 3 / 2 0 0 3

7 / 3 / 2 0 0 3

9 / 3 / 2 0 0 3

1 1 / 3 / 2 0 0 3

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1 1 / 3 / 2 0 0 5



### DateConcentration (ug/m3)

Maxwell Rd/Tombras Ave
Rossville

Figure 37: Comparison of All Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2003-2005)



## Rossville and Maxwell Road/Tombras Avenue 2006-2008

0 5 10 15 20 25 30 35 40 45 50

1 / 5 / 2 0 0 6

3 / 5 / 2 0 0 6

5 / 5 / 2 0 0 6

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1 1 / 5 / 2 0 0 8



### DateConcentration (ug/m3)

Maxwell Rd/Tombras Ave
Rossville

Figure 38: Comparison of All Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2006-2008)Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 61

The Rossville PM 2.5 FRM monitor began sampling on January 1, 2000 with a one in six day schedule. On January 3, 2007, the Rossville site’s sampling schedule changed to one in three day schedule. The Maxwell Road/Tombras Avenue PM 2.5 FRM monitor ran on a one in six day sampling schedule from January 1, 2000 until June 29, 2003. At that time, samples were collected on a one in three day sampling schedule. Then on August 2, 2005, the Maxwell Road/Tombras Avenue PM 2.5 FRM monitor began a one in six day sampling schedule again. On January 1, 2007, the monitor began sampling on a daily schedule. For this analysis, the data was paired when both monitors took a sample. Therefore, until January of 2007, the data pairs were on a one in six day sampling frequency. Then in January of 2007, the data pairs were on a one in three day sampling schedule. In the above graphs, the sampling frequency of paired data is shown to increase in Figure 38, with the 2007 data. There were a total of 486 data points to compare in the nine year time span.

There are many simila rities between the Ro ssville and Maxwell Road/Tombras Avenue sites that were also similar between the Rossville and Siskin Drive sites. The data also seems to track well between the Rossville and Maxwell Road/Tombras Avenue sites. In Figure 36 both the Rossville and Ma xwell Road/Tombras Avenue sites had a spike on January 1, 2000. The Rossville site had a PM 2.5 concentration of 43.1 μ g/m 3 and the Maxwell Road/Tombras Avenue site had 53.3 μ g/m 3 . Both sites have concentrations remaining around 10 μ g/m 3 to 30 μ g/m 3

, following the same fluctuation until October 27, 2000 when both sites spike. The Rossville site samples a PM 2.5 concentration of 48.3 μ g/m 3 while the Maxwell Road/Tombras Avenue site samples 49.5 μ g/m 3 . Then on November 2, 2000 both sites continue the spike in PM 2.5 levels. The Maxwell Road/Tombras Avenue site reports a PM 2.5 concentration of 62.1 μ g/m 3 and the Rossville site reports 48.7 μ g/m 3 . This is the maximum value for both sites over the whole nine years of data, as shown previously in Table 12, Descriptive Statistics. Again the same pattern is followed for both the Rossville and Maxwell Road/Tombras Avenue sites through 2001. Both the Rossville and Maxwell Road/Tombras Avenue sites show a low value on January 31, 2001. Rossville reports a PM 2.5 concentration of 3.3 μ g/m 3 and Maxwell Road/Tombras Avenue reports 5 μ g/m 3 . There is a smaller spike in concentration on November 15, 2001, with Rossville reporting 34 μ g/m 3 and Maxwell Road/Tombras Avenue reporting 45.5 μ g/m 3 . There is an obvious pattern from May 8, 2002 until October 17, 2002, in Figure 36, where both sites show almost the exact same values. When one site’s concentration increased, the other site also increased. When one site’s concentration decreased, the other site also decreased. This timeframe is shown in the following table for ease of viewing. All values are in micrograms per cubic meter ( μ g/m 3 ).Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 62

DateRossville Maxwell Road/Tombras Avenue
5/8/2002 18.9 20.5
5/26/2002 17.4 20.8

6/1/2002 23.5 22.3
6/7/2002 10.7 11.1
6/13/2002 21.8 23

7/7/2002 27.7 26.9
7/19/2002 9.9 9.6
7/25/2002 27.7 27.5
7/31/2002 11.5 10.5
8/12/2002 31.6 32.8
8/18/2002 8.5 7.7 8/30/2002 12.5 11.3

9/5/2002 20 19.6
9/11/2002 32 28
9/17/2002 21.7 21.1
9/23/2002 19.5 18.5
9/29/2002 16 16.2
10/17/2002 9 8.8

Table 24: Example of Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM Data Trend

This pattern continues in 2003. In Figure 37, on March 9, 2003, the Maxwell Road/Tombras Avenue site showed a lo w PM 2.5 concentration of 4.5 μ g/m 3 and the Rossville site also showed a low 2.9 μ g/m 3 . Then on March 15, 2003, the Maxwell Road/Tombras Avenue site’s concentration spikes to 32.5 μ g/m 3 while the Rossville site spikes to 30.7 μ g/m 3 . Then on March 21, 2003 both site’s concentrations drop. The Maxwell Road/Tombras Avenue samples 9.7
μ g/m 3 while the Rossville site samples 10.1 μ g/m 3 . On June 26, 2003 both sites show a spike in the PM 2.5 data. The Rossville site samples 46.9 μ g/m 3 and the Maxwell Road/Tombras Avenue site samples 44.3 μ g/m 3 . Then on July 2, 2003, both sites’ concentrations drop down. The Rossville site samples 3 μ g/m 3 and the Maxwell Road/Tombras Avenue sites samples 3.2
μ g/m 3

. Another example of the similarity in the PM 2.5 FRM data is shown in Figure 37, with the 2005 data. On Au gust 8, 2005, both the Rossville and Maxwell Road/Tombras Avenue sites had low concentrations. The Rossville site sampled 8.2 μ g/m 3 , and the Maxwell Road/Tombras Avenue site sampled 8.4 μ g/m 3 . Then on August 14, 2005 there was an increase in PM 2.5 concentrations at both sites. The Rossville site collected 20.9 μ g/m 3 and Maxwell Road/Tombras Avenue collected 18.9 μ g/m 3 . On August 20, 2005, both site’s concentrations remained relatively steady. The Rossville site sampled 16.9 μ g/m 3 and Maxwell Road/Tombras Avenue sampled 16.4
μ g/m 3 . By August 26, 2005, both sites had increases in concentrations. The Rossville site sampled 32.6 μ g/m 3 while the Maxwell Road/Tombras Avenue site sampled 28.2 μ g/m 3 . There was a decrease in concentrations on September 7, 2005. The Rossville site sampled a PM 2.5 concentration of 16.5 μ g/m 3 and Maxwell Road/Tombras Avenue sampled 15.7 μ g/m 3 . Then on September 13, 2005 both site’s concentrations spiked. The Rossville site collected 36.1 μ g/m 3 and the Maxwell Road/Tombras Avenue site collected 35.8 μ g/m 3

.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 63

In Figure 38, there is another example of both sites showing the same fluctuating pattern with almost ident ical PM 2.5 data. On May 21, 2007 the Rossville site’s concentration was 13.5 μ g/m 3 while the Maxwell Road/Tombras Avenue site sampled 13.2 μ g/m 3 . On May 24, 2007 both site’s concentrations remained steady. The Rossville site sampled 14.8 μ g/m 3 and the Maxwell Road/Tombras Avenue site sampled 13.2 μ g/m 3 . Then on May 27, 2007 both site’s concentrations spiked. The Rossville site sampled a PM 2.5 concentration of 43.9 μ g/m 3 and Maxwell Road/Tombras Avenue site sampled 45.1 μ g/m 3 . On May 30, both sites sampled lower concentrations. The Rossville site sampled 21.6 μ g/m 3 and the Maxwell Road/Tombras Avenue site sampled 20.4 μ g/m 3 . On June 2, 2007 both sites showed higher concentrations. The Rossville site sampled a concentration of 29.8 μ g/m 3 and Maxwell Road/Tombras Avenue sampled 31.2 μ g/m 3 . Then on June 5, 2007, both sites showed even more of a drop in concentration. The Rossville site collected a PM 2.5 concentration of 9.3 μ g/m 3 while the Maxwell Road/Tombras Avenue site collected 8.5 μ g/m 3

. Overall, both the comparisons of the Rossville PM 2.5 FRM data to the Siskin Drive PM 2.5 FRM data and the Maxwell Road/Tombras Avenue PM 2.5 FRM data show very close agreement. This is shown with the data point to data point comparison displayed in Figure 33 through Figure 38. All three site s show similarities with their pattern of fluctuation and levels of PM 2.5 concentration. Typically, when the levels of PM 2.5 concentration remain similar from sample day to sample day at one site, the levels remain similar at all three sites. In general, when there is spike in concentration at one site, all three sites show the spike in PM 2.5 concentration, and when there is a drop in the PM 2.5 concentration, all three sites show the drop in concentration. All three sites show the same trend in PM 2.5 FRM data.

2.9 Removal Bias Analysis

The U.S. EPA created tools that could be used as aides in performing network assessments. One network assessment tool is a removal bias tool. With this tool, one can choose a site to be removed from an area and see if the sites surrounding that site show a significant difference in their values. The explanation in the Draft Network Assessment and Tools Documentation for the removal bias tool states, ‘ The static analyses use the nearest neighbors to each site to estimate the concentration at the location of the site if the site had never existed. This is done using the Voronoi Neighborhood Averaging algorithm with inverse distance weighting where

2 

### 1
d w = with w equal to the weight and d equal to the distance. The squared distance allows for higher weighting on concentrations at sites located closer to the site being examined. The bias was calculated for each day at each site by taking the difference between the predicted value from the interpolation and the measured concentration, and the average bias was compared using a students-t distribution to determine whether or not it was statistically different from zero at a 95% probability. A positive average bias would mean that if the site being examined was removed, the neighboring sites would indicate that the estimated concentration would be larger than the measured concentration. Likewise, a negative average bias would suggest that the estimated concentration at the location of the site is smaller than the actual measured concentration... In Google Earth, statistically insignificant sites are shown as solid dots while other sites are color coded according to the magnitude of their average bias and displayed as rings... The interactive removal bias tool could be run with those sites taken out to see if they are similar to their remaining neighbors or if a bias exists. If a negative bias exists and the site is within a certain range of the NAAQS, the decision needs to be made by the State on whether that particular site still adds value.’Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 64

The following table and Google Earth map were produced with the Removal Bias tool. An analysis was run on the PM 2.5 FRM data. Rossville was removed from the network of PM 2.5 FRM data in the database. The tool calculates the PM 2.5 FRM data as if the Rossville site never existed. The Removal Bias tool shows that the Rossville site’s PM 2.5 FRM data had an average bias of –0.2 μ g/m 3 , with a p-value of 0.647944. This means that the interpolation used to create the estimated PM 2.5 FRM value is –0.2 μ g/m 3 different from the actual PM 2.5 FRM value measured at the Rossville site. The tool shows that this difference (-0.2 μ g/m 3 ) between the interpolated and measured PM 2.5 FRM concentrations is not statistically significant. The PM 2.5 data collected at the neighboring sites and used to create the estimate was not significantly different from the Rossville site’s actual PM 2.5 concentrations. This is a useful tool to show that the PM 2.5 data collected at Rossville’s neighboring sites could be substituted since the PM 2.5 data collected at those neighboring sites is not significantly different.

As stated in the description above, the negative bias indicates that the estimated PM 2.5 FRM concentration at the Rossville site is smaller than the actual measured concentration. In the map below, this negative bias is shown with a blue color. Also from the description above, the solid color for the Rossville site indicates that the difference between the interpolated and measured PM 2.5 FRM concentrations is not significantly different. The list of sites generated by the Removal Bias tool and used in the interpolation is shown on the Google Earth map below. Both the Maxwell Road/Tombras Avenue and the Siskin Drive sites, as well as eight other sites in Alabama, Georgia, and Tennessee, were used in the interpolation. The Removal Bias tool shows that there is not a significantly different concentration of PM 2.5 FRM data being collected at the Rossville site compared to the interpolated concentration calculated from the ten neighboring sites.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 65

siteid latitude longitude dva0608 dvd0608 nickaddr meanbias sdbias nobs pvalue sig

132950002 34.9789 -85.3009 13.7 30 601 Maple St, Rossville GA -0.2 4.179025 108 0.647944 insig

Figure 39: Removal Bias Analysis for the Rossville Site

3.0 Summary

For the timeframe of June 12, 2007 to Nove mber 13, 2007, the Rossville site (AQS ID 13-295- 0002) in Walker County, Georgia did not collect PM 2.5 FRM data. The lapse in data was due to logistical problems beyond GA EPD’s control. The original location, the Rossville Health Center, underwent construction to replace the existing flat roof with a slanted roof. The slanted roof would no longer support the ambient air monitoring equipment. The Rossville site was closed using standard operating procedures, and the Rossville site was relocated within a mile of the original site to keep its existing site identification number. This relocation of the Rossville site was allowed by 40CFR 58.14 System Modification, Paragraph C, (6). This rule states ‘ A SLAMS monitor not eligible for removal under any of the criteria in paragraphs (c)(1) through (c)(5) of this section may be moved to a nearby location with the same scale of representation if logistical problems beyond the State's control make it impossible to continue operation at its current site.’

An important consideration in the developm ent of this document is the number of PM 2.5 monitors required in the Chattanooga, TN-GA MSA. According to the U.S. Census Bureau, the Chattanooga, TN-GA MSA population for 2000 was 465,161. Table D-5 of Appendix D to Part 58 of the Federal Register states that if the MSA has a population of 500,000 to 1,000,000, andGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 66

the most recent 3-year design value is >/=85% of any PM 2.5 NAAQS, there should be two PM 2.5 monitors located within that MSA (71 FR 61321, October 17, 2006). Assuming the population is now within that 500,000 to 1,000,00 range, this would mean that the Chattanooga, TN-GA MSA would need two PM 2.5 monitors. There are currently four PM 2.5 monitors in the Chattanooga, TNGA MSA, with two additional monitors in the MSA than required by the Federal Register. During the June through November 2007 timeframe, there were three other PM 2.5 monitors in the Chattanooga, TN-GA MSA collecting PM 2.5 data.

In addition, if spatial averaging is used as a weight of evidence tool that supports data substitution for the Rossville site for the 2007 third quarter data, then the data should show it can meet the regulation’s requirements. The following regulation applies: 40CFR50, Appendix N, Interpretation of the National Ambient Air Quality Standards for PM 2.5 , Section 4.1.b, “For single site comparisons, 3 years of valid annual means are required to produce a valid annual standard design value. In the case of spatial averaging, 3 years of valid spatially averaged annual means are required to produce a valid annual standard design value. Designated sites with less than 3 years of data shall be included in annual spatial averages for those years that data completeness requirements are met. A year meets data completeness requirements when at least 75 percent of the scheduled sampling days for each quarter have valid data.” For the 2007 PM 2.5 FRM data at the Rossville site, there were 26 samples collected in the first quarter, 18 samples collected in the second quarter (with one exceptional event), 0 samples collected in the third quarter, and 14 samples collected in the fourth quarter. This does not add up to 75 percent for the 2007 data. However, the Rossville PM 2.5 FRM data met the 75 percent data completeness rules for the 2006 and 2008 years of data.

In order to cover the timeframe that the Rossville site did not collect PM 2.5 data, data from two other sites within the same Chattanooga-Tennessee-Georgia MSA was analyzed for potential substitution of that PM 2.5 FRM data. This analysis was done in order to eventually calculate a PM 2.5 design value for the Rossville site.

The spatial averaging rule found in 40CFR50
, Appendix N is a good foundation for understanding the significance PM 2.5 statistical tests. The spatial averaging rule has a number of strict statistical tests that must be met in order to spatial average PM 2.5 data. These statistical tests include: (1) The annual mean concentration at each site shall be within 10 percent of the spatially averaged annual mean. (2) The daily values for each site pair shall yield a correlation coefficient of at least 0.9 for each calendar quarter. (3) All of the monitoring sites should principally be affected by the same major emission sources of PM 2.5 ... all major component concentration averages to be within 10 percent for each calendar quarter. (4) The requirements in the paragraphs (b)(1) through (3) of this section shall be met for 3 consecutive years in order to produce a valid spatially averaged annual standard design value. Otherwise, the individual (single) site annual standard design values shall be compared directly to the level of the annual NAAQS.’ As discussed above, the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue PM 2.5 data generally met the spatial averaging tests since 2000.

This document has shown a number of analyses done on three of the PM 2.5 sites within the Chattanooga, TN-GA MSA. A comparison was made between the Rossville site and theGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 67

Maxwell Road/Tombras Avenue, and the Siskin Driv e sites. In addition to examining the above criteria regarding the PM 2.5 data, additional analyses were also performed. Site details, maps, and distances of each site from the Rossville site were examined. Pearson Product-Moment Correlations were calculated for all the data collected, for the months that data was not collected at the Rossville site, and for each individual quarter of data collected. A comparison of annual means and differences between annual means and spatial averages were calculated. Linear regressions were plotted on all available paired data and resulting scatter plots and R 2 valueswere evaluated. A box plot was graphed and displayed in the document. Pearson ProductMoment Correlation, linear regressions, R 2 values, quarterly percent differences, quarterly absolute differences, and quarterly percent contributions were all calculated on select speciation data. Sources of emissions affecting each site were examined and a source apportionment model was run on the speciation data. An investigation of the meteorological conditions affecting the sites were investigated and summarized. A trend of each data point was examined with a line graph of all the data. A Removal Bias tool was applied to the Rossville site in order to show how the available data would be affected by its removal. The research was done in order to demonstrate alternatives for calculating the PM 2.5 2006-2008 design value at the Rossville site.

With the examination of the site details, it is shown that the Rossville sites (original and current location) are in close in proximity to the Maxwell Road/Tombras Avenue and Siskin Drive sites. The Rossville sites also have similar land use compared to the Maxwell Road/Tombras Avenue and Siskin Drive sites. The location of the Ro ssville-Health Center and Rossville-Maple Center sites is a suburban setting, with some residential areas in the surroundings. The Maxwell Road/Tombras Avenue site is located in an urban area, with businesses and a residential setting. The location of the Siskin Drive site is also in an urban area, with its immediate surroundings of businesses and industries. The distance from the Rossville-Health Center site to the Maxwell Road/Tombras Avenue site is only 3.63 miles, and the distance from the Rossville-Health Center site to the Siskin Driv e site is 5.81 miles. The distance from the Rossville-Maple Street site to the Maxwell Road/Tombras Avenue site is only 3.5 miles, and the distance from the Rossville-Maple Street site to the Siskin Drive site is 5.0 miles.

According to the Pearson Product-Moment Correlat ions derived from the different types of data (PM 2.5 FRM data and PM 2.5 speciation mass), it appears that the Rossville PM 2.5 FRM and Siskin Drive PM 2.5 FRM complete datasets from 2000 to 2008 show the strongest correlation, 0.91609. The correlation between the Rossville PM 2.5 FRM and Maxwell Road/Tombras Avenue PM 2.5 FRM complete datasets from 2000 to 2008 is also very strong, 0.91362.

Comparing each month and season showed relatively high Pearson Product-Moment Correlations across the months and seasons that the Rossville site did not collect data in 2007. When comparing the Rossville and Siskin Drive sites, the correlations ranged from 0.76562 in September to 0.97814 for June. For the Maxwell Road/Tombras Avenue and Rossville sites, the correlations ranged from 0.81186 in September to 0.98300 in October. For the seasonal comparisons, the strongest relationship between the Rossville and Siskin Drive sites was during June through August (0.93303). The strongest seasonal relationship between the Rossville and Maxwell Road/Tombras Avenue sites was during October through November (0.95158).

Of the 35 quarterly Pearson Product-Moment Correlations calculated, 28 PM 2.5 FRM correlations were above 0.9 for the Rossville and Siskin Drive comparisons. There is a timeframe from the second quarter of 2004 through the fourth quarter of 2007 when all the correlations are greater than 0.9 for the Rossville and Siskin Drive sites. There were 24 PM 2.5 FRM quarterly correlations above 0.9 for the Rossville and Maxwell Road/Tombras AvenueGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 68

comparison. For the available 2007 data used in the correlations, all three quarters were above 0.9 for all of the site comparisons.

All of the percent differences between the 2000 to 2008 PM 2.5 FRM annual means data for Rossville compared to the Maxwell Road/Tom bras Avenue and Siskin Drive sites showed differences less than 10% for each year.

All of the means of the total paired data co mparisons between the Rossville and Siskin Drive sites were below the 10% used as guidance. Also, all of the means of the paired data comparisons between Rossville and Maxwell Road/Tombras Avenue sites were below the 10% used as guidance. The Rossville and Siskin Drive PM 2.5 FRM data comparison was from January 1, 2000 to December 29, 2008 and had a 2.50% difference, much lower than 10%. The Rossville and Maxwell Road/Tombras Avenue PM 2.5 FRM data comparison was from January 1, 2000 to December 29, 2008 and had a 0.20% difference, also much lower than 10%. The Rossville PM 2.5 speciation mass and Siskin Drive PM 2.5 FRM data comparison March 23, 2005 to March 26, 2009 and had a 9.19% difference. The Rossville PM 2.5 speciation mass and Siskin Drive PM 2.5 speciation mass data comparison was from March 23, 2005 to December 26, 2008 and had a –3.57% difference. The Rossville PM 2.5 speciation mass and Maxwell Road/Tombras Avenue PM 2.5 FRM data comparison was from March 23, 2005 to December 26, 2008 and had a 5.13% difference.

To use the spatial average guideline and examine possible spatial average calculations, the sites within the Chattanooga, TN-GA MSA were grouped several ways to make comparisons of the annual means. All of the percent difference comparisons between the Rossville site and the spatial average of the Rossville and Maxwell Road/ Tombras Avenue sites were very low, below +/-3.42%. All of the percent difference compar isons between the Rossville site and the spatial average of the Rossville and Siskin Drive sites were also very low, below +/-3.73%. All of the percent difference comparisons between the Rossville site and the spatial average of the Rossville, Maxwell Road/Tombras Avenue, and Siskin Drive sites were also very low, below +/- 3.60%. All of these comparisons were well below the 10% guidance [40CFR50
, Appendix N, paragraph (2.0) (B) (1)].

With a comparison of all of the R 2 values derived from the linear regressions, the Rossville and Siskin Drive PM 2.5 FRM monitors show the strongest relationship, with 0.8386. This corresponds with the strongest relationship found when calculating the Pearson Product-Moment Correlation in this analysis. The Pearson Product-Moment Correlation between the Rossville and Siskin Drive PM 2.5 FRM monitors was 0.91609. The next highest R 2 value was derived from the linear regression comparison between the Rossville and the Maxwell Road/Tombras Avenue PM 2.5 FRM monitors. The R 2 value was 0.8347. This also corresponds with the second highest Pearson Product-Moment Correlation for the comparison between the Rossville site and the Maxwell Road/Tombras Avenue site, which wa s 0.91362. These linear regressions were examining all paired PM 2.5 FRM data collected from January 1, 2000 to December 29, 2008.

In order to further explore the comparison of PM 2.5 FRM data collected at the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites, box plots with descriptive statistics were examined. Descriptive statistics and a box plot were generated for the complete PM 2.5 FRM datasets with SigmaStat. The results show that the mean, standard deviation, standard error, median, 25%, and 75% of the data at the Rossv ille, Siskin Drive, and Maxwell Road/Tombras Avenue are almost identical.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 69

Since the Rossville and Siskin Drive sites showed one of the strongest relationships and both sites collect PM 2.5 speciation data, more analyses were performed on select PM 2.5 speciation data. The PM 2.5 species evaluated were organic carbon, elemental carbon, sulfate, ammonium ion, total nitrate, aluminum, silicon, and potassium. In the PM 2.5 speciation analyses, sulfate showed a very strong relationship between the Rossville site and Siskin Drive site data. With the analysis of the select PM 2.5 speciation data, the Pearson Product-Moment Correlation of the overall dataset from 2005 to 2008, the linear regression and R 2 value of the overall dataset, the quarterly percent differences, and quarterly percent contributions all consistently showed sulfate to have a very strong relationship between the data collected at the Rossville and Siskin Drives sites. The Pearson Product-Moment Correlation was 0.98717. The R 2 value was 0.9744. For thirteen out of the available fourteen calendar quarters from 2005 to 2008, the sulfate data was within 10% difference for the Rossville and Siskin Drive sites. One quarter was slightly outside the range with a percent difference of –12.87%. Both the Rossville and Siskin Drive sites show sulfate as one of the principal speciation constituents of the PM 2.5 data. Also, both sites seem to follow the same trend of sulfate percent contribution through the period of sampling data.

In addition to the above PM 2.5 speciation analyses, a source apportionment model was performed on the PM 2.5 speciation data. This PMF model shows that sulfate is the largest component contributing to the total PM 2.5 collected at the Rossville (38.3%) and Siskin Drive (37.2%) sites. Both the Rossville and Siskin Drive sites are principally affected by sulfate sources, and secondary sulfate is the largest source for both Walker County, GA and Hamilton County, TN. For both sites, the secondary sulfate is found similarly during the week as on the weekend. Also, both sites show the high season to be in the summer and the low season to be in the winter. These analyses were performed to verify that the PM 2.5 data meets the regulation (40CFR50
, Appendix N) used as guidance for this document.

To show that the PM 2.5 standard is met with incomplete data, EPA’s Guideline on Data Handling Conventions for the PM NAAQS, Chapter 1, paragraph (9) explains to show that the meteorology for the substituted data compares to the quarters in question. With this analysis, it is found that the city of Rossville in Walker County, Georgia has a comparable meteorological regime to neighboring Hamilton County, Tennessee due to similar topography, geographic location and generally concurrent synoptic and meso-synoptic conditions. Specific meteorological parameters, such as wind speed, wind direction, and relative humidity, among others, have shown in past studies to have a direct correlation with fine particulate matter (PM 2.5 ) concentrations. The observed corresponding relationship then between the PM 2.5 trends at the Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue sites may be partially attributed to this shared meteorology. In summary, based on meteorological analysis and observed similarities between surface and upper air observations, it is believed that either site could be used to represent the other with regard to PM 2.5 concentrations.

With the line graph comparisons of the Rossville PM 2.5 FRM data to the Siskin Drive PM 2.5 FRM data and the Maxwell Road/Tombras Avenue PM 2.5 FRM data, both evaluations show very close agreement. All three sites show similarities with their pattern of fluctuation and levels of PM 2.5 concentration. Typically, when the levels of PM 2.5 concentration remain similar from sample day to sample day at one site, the levels remain similar at all three sites. In general, when there is spike in concentration at one site, all three sites show the spike in PM 2.5 concentration, and when there is a drop in the PM 2.5 concentration, all three sites show the drop in concentration. All three sites show the same trend in PM 2.5 FRM data.

The Removal Bias tool shows that this difference (-0.2 μ g/m 3 ) between the interpolated and measured PM 2.5 FRM concentrations is not statistically significant. The PM 2.5 data collected atGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 70

the neighboring sites and used to create the estimate was not significantly different from the Rossville site’s actual PM 2.5 concentrations. This shows that the PM 2.5 data collected at Rossville’s neighboring sites could be substituted since the PM 2.5 data collected at those neighboring sites is not significantly different.

After reviewing the analyses, it appears that there is a strong relationship between both the Rossville and Siskin Drive sites and between th e Rossville and Maxwell Road/Tombras Avenue sites. The following tables show the exploration of calculating the 2006-2008 design value for the Rossville site using the Siskin Drive site and the Maxwell Road/Tombras Avenue site. To be thorough, the use of both data substitution and spatial averaging are examined.

3.1 Data Substitution

The analyses completed showed that the Rossville si te had very comparable historical data with both the Siskin Drive site and the Maxwell R oad/Tombras Avenue site. Comparisons between the Rossville site and both the Siskin Dr ive and Maxwell Road/Tombras Avenue sites showed high correlations for the overall dataset, overall higher correlations for the quarterly comparisons, very low percent differences between complete datasets and annual means, and higher R 2 values. In addition, the Rossville and Siskin Drive sites showed similar speciation data. With this research showing these similar datasets, both the Siskin Drive and Maxwell Road/Tombras Avenue PM 2.5 FRM data was substituted for the Rossville site PM 2.5 FRM data in three different scenarios for thoroughness.

For the following Siskin Drive PM 2.5 FRM data substitutions, the weighted annual mean for 2007 was calculated manually with Excel. There were three data points taken out. One data point was the exceptional event at the Rossville site on May 27. There were two filters with ‘temperature difference out of spec’ at the Siskin Drive site on June 29 and August 28 taken out of the dataset. There was no collocated data to substitute for these two data points at the Siskin Drive site. There was one missing sample at the Siskin Drive site on July 2, with a null code of AG. This data point was substituted with a collocated value from the collocated PM 2.5 monitor at the Siskin Drive site. The quarterly means were calculated, and then the weighted annual mean was calculated from the quarterly means. Both the Rossville and Siskin Drive sites had a one in three day sampling schedule in 2007. This same procedure was used for each of the following data substitutions where dates were applicable.

With the Siskin Drive PM 2.5 FRM data substituted for the missing Rossville PM 2.5 FRM data for every data point from June 12 to November 13, 2007, the weighted annual mean would be 15.44 μ g/m 3 for 2007.The following table shows the calculation of the 2006-2008 design value for the Rossville site, with the Siskin Drive PM 2.5 FRM data substituted from June 12 through November 13, 2007 . The 2006 and 2008 values were taken from AQS, and the 2007 value was calculated manually with Excel. The 2006-2008 design value for the Rossville site would be 14.1
μ g/m 3

.

Calculation of Rossville PM 2.5 Annual Design Value with 2007 Siskin Drive Data Substituted ( μ g/m 3 )
2006 14.45
2007 15.44*
2008 12.48 2006-2008 Design Value 14.1 *calculated manuallyGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 71

The following table shows the calculation of the 2006-2008 design value for the Rossville site, with the Siskin Drive PM 2.5 FRM data substituted for third quarter and part of fourth quarter 2007. The 2006 and 2008 values were taken from AQS, and the 2007 value was calculated manually with Excel. The 2006-2008 design value for the Rossville site would be 14.0 μ g/m 3

.

Calculation of PM 2.5 Annual Design with Siskin Drive Substituted for 3 rd Quarter and Part of 4 th Quarter Data from 2006-2008 ( μ g/m 3 )
2006 14.45 2007 15.08*
2008 12.48 2006-2008 Design Value 14.0 *calculated manually

The following table shows the calculation of the 2006-2008 design value for the Rossville site, with the Siskin Drive PM 2.5 FRM data substituted from for the third quarter of 2007 only

. The 2006 and 2008 values were taken from AQS, and the 2007 value was calculated manually with Excel. The 2006-2008 design value for the Rossville site would be 14.1 μ g/m 3

.

Calculation of PM 2.5 Annual Design with Siskin Drive Substituted for 3 rd Quarter Only Data from 2006- 2008 ( μ g/m 3 )
2006 14.45 2007 15.29*
2008 12.48 2006-2008 Design Value 14.1 *calculated manually

With all three scenarios of Siskin Drive PM 2.5 FRM data substitution, the annual mean for 2007 was above the standard of 15.0 μ g/m 3

. Even with the substituted 2007 PM 2.5 FRM data above the 15.0 μ g/m 3 standard, all three scenarios of substitution showed a three-year design value below 15.0 μ g/m 3

.
For the following Maxwell Road/Tombras Avenue PM 2.5 FRM data substitutions, the weighted annual mean for 2007 was calculated manually with Excel. There was one data point taken out that was caused by an exceptional event at t he Rossville site on May 27 and concurred by EPA. There were no exceptional event days concu rred by EPA for the Maxwell Road/Tombras Avenue site during the timeframe of substitution. The Maxwell Road/Tombras Avenue site was on a daily sampling schedule in 2007. In order to substitute the data as if it were collected at the Rossville site, every third sampling day was used in the calculations. A one in three day sampling schedule was used as if the data had been collected at the Rossville site. There was one missing sample at the Maxwell Road/Tombras Avenue site on October 9, with a null code of AG. There was no collocated data to substitute for this data point. The quarterly means were calculated, and then the weighted annual mean was calculated from the quarterly means. This same procedure was used for each of the following data substitutions where dates were applicable.

With the Maxwell Road/Tombras Avenue PM 2.5 FRM data substituted for the missing Rossville PM 2.5 FRM data for every data point from June 12 to November 13, 2007, the weighted annualGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 72

mean would be 15.22 μ g/m 3 for 2007. The following table shows the calculation of the 2006- 2008 design value for the Rossville site, with the Maxwell Road/Tombras Avenue PM 2.5 FRM data substituted from June 12 through November 13, 2007 . The 2006 and 2008 values were taken from AQS, and the 2007 value was calculated manually with Excel. The 2006-2008 design value for the Rossville site would be 14.1 μ g/m 3

.

Calculation of Rossville PM 2.5 Annual Design Value with 2007 Maxwell Road/Tombras Avenue Data Substituted ( μ g/m 3 )
2006 14.45
2007 15.22*
2008 12.48 2006-2008 Design Value 14.1 *calculated manually

The following table shows the calculation of the 2006-2008 design value for the Rossville site, with the Maxwell Road/Tombras Avenue PM 2.5 FRM data substituted for third quarter and part of fourth quarter 2007. The 2006 and 2008 values were taken from AQS, and the 2007 value was calculated manually with Excel. The 2006-2008 design value for the Rossville site would be13.9 μ g/m 3

.

Calculation of PM 2.5 Annual Design with Maxwell Road/Tombras Avenue Substituted for 3 rd Quarter and Part of 4 th Quarter Data from 2006-2008 ( μ g/m 3 )
2006 14.45 2007 14.89*
2008 12.48 2006-2008 Design Value 13.9 *calculated manually

The following table shows the calculation of the 2006-2008 design value for the Rossville site, with the Maxwell Road/Tombras Avenue PM 2.5 FRM data substituted from for the third quarter of 2007 only . The 2006 and 2008 values were taken from AQS, and the 2007 value was calculated manually with Excel. The 2006-2008 design value for the Rossville site would be 14.0 μ g/m 3

.

Calculation of PM 2.5 Annual Design with Maxwell Road/Tombras Avenue Substituted for 3 rd Quarter Only Data from 2006-2008 ( μ g/m 3 )
2006 14.45 2007 15.16*
2008 12.48 2006-2008 Design Value 14.0 *calculated manually

With two of the three scenarios of Maxwell Road/Tombras Avenue PM 2.5 FRM data substitution, the annual mean for 2007 was above the standard of 15.0 μ g/m 3

. Even with the substituted 2007 PM 2.5 FRM data above the 15.0 μ g/m 3 standard, all three scenarios of substitution showed a three-year design value below 15.0 μ g/m 3

.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 73

3.2 Spatial Averages

As an alternative to substituting the PM 2.5 FRM data from the Siskin Drive site or the Maxwell Road/Tombras Avenue site at the Rossv ille site, spatially averaging the PM 2.5 FRM data was examined. To cover different possible ways of spatial averaging the PM 2.5 FRM data in the Chattanooga Tennessee-Georgia MSA, three different scenarios were explored.

The first scenario looks at the spatial average using unadjusted AQS values for the Rossville, Maxwell Road/Tombras Avenue, and Siskin Drive sites. This includes the incomplete year of 2007 data for Rossville. The PM 2.5 annual means were taken directly from AQS. If spatial averaging is used to calculate the 2006-2008 PM 2.5 annual design value, the result would be 13.9 μ g/m 3 using unadjusted AQS values for the Rossville, Maxwell Road/Tombras Avenue, and Siskin Drive , with similar land use, that are within the Chattanooga Tennessee-Georgia MSA. This includes the incomplete 2007 annual mean for the Rossville site.

Calculation of Spatial Average PM 2.5 Annual Design with Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue Sites Unadjusted from AQS ( μ g/m 3 )
2006 14.55 2007 14.55 2008 12.52 2006-2008 Design Value 13.9

The second scenario calculates the spatial average for only the Maxwell Road/Tombras Avenue and Siskin Drive sites. This scenario does not include the incomplete year of data for the Rossville site. The PM 2.5 annual means were taken directly from AQS. If spatial averaging is used to calculate the 2006-2008 PM 2.5 annual design value, the result would be 14.0 μ g/m 3 using unadjusted AQS values for only the Maxwell Road/Tombras Avenue and Siskin Drive

, with similar land use, that are within the Chattanooga Tennessee-Georgia MSA. This does not include the incomplete 2007 annual mean for the Rossville site.

Calculation of Spatial Average PM 2.5 Annual Design with Siskin Drive and Maxwell Road/Tombras Avenue Sites Unadjusted from AQS ( μ g/m 3 )

2006 14.60 2007 14.99 2008 12.55 2006-2008 Design Value 14.0

The third scenario computes the spatial aver age for only the Maxwell Road/Tombras Avenue and Siskin Drive sites for the 2007 data, but includes the Rossville site for 2006 and 2008. This procedure is given in Chapter 1, paragraph 4 of EPA’s Guideline on Data Handling Conventions for the PM NAAQS. This explanation of calculating the three-year design value uses the PM 2.5 annual means from sites with sufficient data. If there is a year of insufficient data at a site, that particular site is left out of the calculation for that year. This scenario does not include the incomplete year of data for the Rossville site. The annual means were taken directly from AQS. If spatial averaging were used to calculate the 2006-2008 PM 2.5 annual design value, the result would be 14.0 μ g/m 3 using unadjusted AQS values for only the Maxwell Road/TombrasGeorgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 74

Avenue, Siskin Drive for 2007 and Rossville included for 2006 and 2008. This does not include the incomplete 2007 annual mean for the Rossville site.

Calculation of Spatial Average PM 2.5 Annual Design with Siskin Drive, Maxwell Road/Tombras Avenue Sites, and Rossville for 2006 and 2008 ( μ g/m 3 )
2006 14.55 2007 14.99 2008 12.52 2006-2008 Design Value 14.0

With all three scenarios examining spatial averages, the 2006-2008 design values were below the PM 2.5 annual standard of 15.0 μ g/m 3 . The scenarios covered three year averages that included the Rossville site for the 2007 PM 2.5 data, and that excluded the Rossville 2007 PM 2.5 data. The scenarios covered averages with similar land use, and with all four sites within the Chattanooga, TN-GA MSA regardless of land use. Although GA EPD is not proposing that spatial averaging be used in this case, these possibilities were examined to show how the Chattanooga, TN-GA MSA would compare to the PM 2.5 annual standard with these averages.

3.3 Conclusion

With this research, GA EPD has shown that a 2006-2008 annual design value could be calculated for the Rossville PM 2.5 FRM sampler using data substituted from the Siskin Drive site or the Maxwell Road/Tombras Avenue site. GA EPD has shown that this is a valid way of representing the data and making an attainment decision. From the weight of evidence provided, GA EPD anticipates that the EPA will agree with the findings herein, proceed with themodified data substitution, and apply it to the design value calculation for the Chattanooga, TNGA MSA.Georgia Department of Natura l Resources/EPD 5/5/2010 Analysis of Rossville PM 2.5 Data Page 75

4.0 References

Code of Federal Regulations, Title 40, Protection of the Environment, Parts 50 and 58.

U.S. Census Bureau, http://factfinder.census.gov

U.S. EPA, 1999. Guideline on Data Handling Conventions for the PM NAAQS. EPA-454/R-99- 008, April 1999.

http://www.epa.gov/ttn/amtic/netassess/documentation/draft_Network_Assessment_tools_docu mentation.doc