GEORGIA DEPARTMENT OF NATURAL RESOURCES 

ENVIRONMENTAL PROTECTION DIVISION 

Air Protection Branch 

Ambient Monitoring Program 

Analysis of Rossville PM2.5 Data 

Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 location 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 the 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 PM2.5 sites in the Chattanooga, TN-GA MSA. GA 

EPD met with Doug Neeley, Branch Chief of the Air, Pesticides, and Toxics Grant Management 

Unit 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 criteria. 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 PM2.5 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 PM2.5 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 PM2.5 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 was given to several rules and other factors. 

Many considerations were made involving the number of required PM2.5 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 meeting all of EPA’s requirements. GA EPD also 

drew from past experience. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 

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 PM2.5 NAAQS, there 

should be two PM2.5 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 PM2.5 monitors. There are currently four PM2.5 

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 PM2.5 monitors in the Chattanooga, TN-GA MSA collecting PM2.5 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 PM2.5 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 PM2.5 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 PM2.5 sites within the Chattanooga, TN-GA MSA, alternatives for 

calculating the PM2.5 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 R2

 values are shown. A 

box plot was graphed and displayed in the document. Pearson Product-Moment Correlation, 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 3

linear regressions, R2 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 PM2.5 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 PM2.5 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 PM2.5 FRM sampler at the Rossville-Health Center location 

(Figure 1) on January 1, 2000. A PM2.5 speciation monitor began monitoring on March 23, 2005, 

and a continuous PM2.5 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 PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 following 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 Area 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 5

 

 

 

 

Figure 1: Rossville-Health Center Site Directional Photographs 

South 

West 

North 

East 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 

East 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 7

1.3 Sites Used in Comparison 

Two PM2.5 FRM sites within the Chattanooga Tennessee-Georgia MSA were used for 

comparison with the PM2.5 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 PM2.5 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 PM2.5 FRM data since January 1, 1999, PM2.5 speciation data including PM2.5 mass 

readings since November 27, 2001, and PM2.5 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 immediate 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 Street 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 Maxwell 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 between 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 distance 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 8

Figure 3: Rossville-Health Center Map 

Figure 4: Maxwell Road/Tombras Avenue Map 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 9

Figure 5: Siskin Drive Map 

Figure 6: Rossville-Maple Street Map 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 10

3.63 miles

0.89 mile 

5.81 miles

Figure 7: Distance from Rossville-Health Center Site 

 

3.5 miles

5.0 miles

Figure 8: Distance from Rossville-Maple Street Site 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 data. This includes comparing PM2.5 FRM data to PM2.5 FRM data and 

PM2.5 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 PM2.5

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 PM2.5 FRM data collected, as early as data was collected. Percent differences 

between annual means of PM2.5 FRM data were calculated and graphed for each pair of sites. 

Percent differences for means across complete datasets were calculated for the PM2.5 data 

(including FRM and speciation mass readings). Percent differences between annual means and 

spatial averages of annual means of PM2.5 FRM data were examined. R2 values with linear 

regressions were calculated and plotted on the PM2.5 data (including FRM and speciation mass 

readings). Descriptive statistics and a box plot analysis was performed with SigmaStat and 

displayed. Select PM2.5 speciation data at the Rossville and Siskin Drive sites was examined 

with Pearson Product-Moment Correlations, linear regressions and R2

 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 performed 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 PM2.5 FRM data collected at the 

surrounding sites is significantly different from 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 PM2.5 attainment 

designation, to show a weight of evidence following the rigorous spatial averaging guidelines 

seems beneficial. The above analyses were performed 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 PM2.5. 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 measurements so as the data may 

be used for attainment designation. 

2.1 Correlations 

To follow the 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 

PM2.5 data were examined. Pearson Product-Moment Correlations were performed on PM2.5

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 PM2.5 FRM data collection. 

Pearson Product-Moment Correlations 

All Possible Data Included Dates* Correlation

Rossville PM2.5 FRM vs. Maxwell Road PM2.5 FRM 1/1/00 to 12/29/08 0.91362

Rossville PM2.5 FRM vs. Siskin Dr PM2.5 FRM 1/1/00 to 12/29/08 0.91609

Rossville PM2.5 Speciation Mass vs. Siskin Drive PM2.5 FRM 3/23/05 to 3/26/09 0.89754

Rossville PM2.5 Speciation Mass vs. Siskin Drive PM2.5 Speciation Mass 3/23/05 to 12/26/08 0.80974

Rossville PM2.5 Speciation Mass vs. Maxwell Road PM2.5 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 PM2.5 FRM and Siskin Drive PM2.5 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 PM2.5 FRM and Maxwell Road/Tombras Avenue 

PM2.5 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 

PM2.5 speciation mass readings at the Rossville and Siskin Drive sites.

A Pearson Product-Moment Correlation was derived for each month (June through November) 

that PM2.5 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 PM2.5 FRM data was compared to the Siskin Drive PM2.5 FRM data and the 

Maxwell Road/Tombras Avenue PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 13

Comparison of Rossville and Siskin 

Drive PM2.5 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 PM2.5 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 PM2.5 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 the Rossville and Maxwell Road/Tombras Avenue 

monthly comparison. For all the monthly correlations, 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 14

Each quarter of PM2.5 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 PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 15

Quarterly Correlations of 

Rossville and Siskin Drive 

PM2.5 FRM Data 

Quarterly Correlations of 

Rossville and Maxwell 

Road/Tombras Avenue PM2.5

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 PM2.5 FRM correlations are above the required 0.9 (highlighted in yellow). Of the 

35 quarterly correlations calculated, 28 PM2.5 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 the 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 16

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

comparisons. 

There were 24 PM2.5 FRM quarterly correlations above 0.9 for the Rossville and Maxwell 

Road/Tombras Avenue comparison. If the correlations 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 PM2.5 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 PM2.5

NAAQS. This is part of the process used in calculating the PM2.5 FRM annual means to 

eventually compare to the PM2.5 annual standard. 

The first section of the table compares the Rossville and Maxwell Road/Tombras Avenue PM2.5

FRM annual means. The second section of the table compares the Rossville and Siskin Drive 

PM2.5 FRM annual means. The resulting percent difference is shown for each year. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 17

Comparison of Annual Means (μg/m3) 

 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 PM2.5 FRM annual means data for Rossville 

compared to Maxwell Road/Tombras Avenue and Siskin 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 PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 18

Rossville and Maxwell Road/Tombras Avenue PM2.5 FRM 

Annual Means 

10

12

14

16

18

20

2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

Average (ug/m 3

)

Rossville Maxwell Road/ Tombras Avenue

Figure 9: Comparison of PM2.5 FRM Annual Means (Rossville and Maxwell Road/Tombras 

Ave) 

Rossville and Siskin Drive PM2.5 FRM Annual Means

10

12

14

16

18

20

2000 2001 2002 2003 2004 2005 2006 2007 2008

Year

Average (ug/m3

)

Rossville Siskin Drive

Figure 10: Comparison of PM2.5 FRM Annual Means (Rossville and Siskin Drive) 

Graphing the PM2.5 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, PM2.5 data (including FRM and speciation mass readings) were 

examined for differences in means. To compare the 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. If 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 (μg/m3) with Each Pair of Data 

Rossville PM2.5 FRM Mean Siskin Drive PM2.5 FRM Mean Percent Difference Dates* 

14.83 14.47 2.50% 1/1/00 to 12/29/08

Rossville PM2.5 FRM Mean 

Maxwell Road/Tombras Avenue PM2.5 FRM 

Mean Percent Difference Dates* 

14.96 14.93 0.20% 1/1/00 to 12/29/08

Rossville PM2.5 Speciation Mass 

Mean Siskin Drive PM2.5 FRM Mean Percent Difference Dates* 

15.36 14.07 9.19% 3/23/05 to 3/26/09

Rossville PM2.5 Speciation Mass 

Mean Siskin Drive PM2.5 Speciation Mass Mean Percent Difference Dates* 

15.85 16.44 -3.57% 3/23/05 to 12/26/08

Rossville PM2.5 Speciation Mass 

Mean 

Maxwell Road/Tombras Avenue PM2.5 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 Avenue sites were below the 10% used as 

guidance. The Rossville and Siskin Drive PM2.5 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 PM2.5 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 

PM2.5 speciation mass and Siskin Drive PM2.5 FRM data comparison March 23, 2005 to March 

26, 2009 and had a 9.19% difference. The Rossville PM2.5 speciation mass and Siskin Drive 

PM2.5 speciation mass data comparison was from March 23, 2005 to December 26, 2008 and 

had a –3.57% difference. The Rossville PM2.5 speciation mass and Maxwell Road/Tombras 

Avenue PM2.5 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 the EPA’s guidance for spatial averaging, 40CFR50, 

Appendix N, paragraph (2.0) (B) (1) as a tool for developing the weight of evidence for 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 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 PM2.5 FRM data was used to determine 

spatial averages, and all data was extracted from 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 PM2.5 FRM annual means to eventually compare to 

the PM2.5 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 spatially 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 spatially 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 difference 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 (μg/m3) 

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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 21

 

Spatial Average of Rossville 

and Siskin Drive (μg/m3) 

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 

(μg/m3) 

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 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%. 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 Maxwell 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 22

In Table 8, 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%. 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 PM2.5 data (including 

FRM and speciation mass readings), linear regressions and resulting R2 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 PM2.5 data compared at 

each site and the dates of data compared. 

All Possible Data Included Dates* 

Rossville PM2.5 FRM vs. Siskin Drive PM2.5 FRM 1/1/00 to 12/29/08 

Rossville PM2.5 FRM vs. Maxwell Road/Tombras Avenue PM2.5 FRM 1/1/00 to 12/29/08 

Rossville PM2.5 Speciation Mass vs. Siskin Drive PM2.5 FRM 3/23/05 to 3/26/09 

Rossville PM2.5 Speciation Mass vs. Siskin Drive PM2.5 Speciation Mass 3/23/05 to 12/26/08 

Rossville PM2.5 Speciation Mass vs. Maxwell Road PM2.5 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 PM2.5 Comparisons 

The following graphs show the results of the linear regressions and resulting R2 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 (μg/m3

). Following the series 

of graphs is a summary table showing all the R2 values for all of the datasets compared. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 23

Rossville PM2.5 FRM vs. Siskin Drive PM2.5 FRM

y = 0.9697x

R2

 = 0.8386

0

10

20

30

40

50

60

70

80

0 10 20 30 40 50

Rossville PM2.5 FRM

Siskin Drive PM2.5 FRM

Figure 11: Comparison of Rossville PM2.5 FRM and Siskin Drive PM2.5 FRM 

Rossville vs. Maxwell Road/Tombras Avenue PM2.5 FRM

y = 0.9839x

R2

 = 0.831

0

10

20

30

40

50

60

70

0 10 20 30 40 50

Rossville PM2.5 FRM

Maxwell Road/Tombras 

Avenue PM2.5 FRM

Figure 12: Comparison of Rossville PM2.5 FRM and Maxwell Road/Tombras Avenue PM2.5

FRM 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 24

Rossville PM2.5 Speciation Mass vs. Siskin Drive PM2.5 

FRM

y = 1.067x

R2

 = 0.7962

0

10

20

30

40

50

60

0 10 20 30 40 50

Siskin Drive PM2.5 FRM

Rossville PM2.5 

Speciation Mass

Figure 13: Comparison of Rossville PM2.5 Speciation Mass and Siskin Drive PM2.5 FRM 

Rossville PM2.5 Speciation Mass vs. Siskin Drive PM2.5 

Speciation Mass

y = 0.9857x

R2

 = 0.6039

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Rossville PM2.5 Speciation Mass

Siskin Drive PM2.5 

Speciation Mass

Figure 14: Comparison of Rossville PM2.5 Speciation Mass and Siskin Drive PM2.5

Speciation Mass 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 25

Rossville PM2.5 Speciation Mass vs. Maxwell 

Road/Tombras Avenue PM2.5 FRM

y = 1.0221x

R2

 = 0.7846

0

10

20

30

40

50

60

0 10 20 30 40 50 60

Maxwell Road/Tombras Avenue PM2.5 FRM

Rossville PM 2.5 

Speciation Mass

Figure 15: Comparison of Rossville PM2.5 Speciation Mass to Maxwell Road/Tombras 

Avenue PM2.5 FRM

The following table summarizes the R2

 values for all of the above linear regressions. 

Sites Compared R2

Rossville PM2.5 FRM vs. Siskin Drive PM2.5 

FRM 0.8386 

Rossville PM2.5 FRM vs. Maxwell Road PM2.5 

FRM 0.8310 

Rossville PM2.5 Speciation Mass vs. Siskin 

Drive PM2.5 FRM 0.7962 

Rossville PM2.5 Speciation Mass vs. Siskin 

PM2.5 Speciation Mass 0.6039 

Rossville PM2.5 Speciation Mass vs. Maxwell 

Road PM2.5 FRM 0.7846 

Table 10: Summary of R2 Values

The above linear regression graphs and table were produced using all available years of PM2.5 

data derived from AQS and omitting any unpaired 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 PM2.5 data (FRM and speciation mass) available at each site, and on three 

sites within the Chattanooga, TN-GA MSA with PM2.5 FRM monitors. 

With a comparison of all of the R2

 values derived from the linear regressions, the Rossville and 

Siskin Drive PM2.5 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 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 26

Drive PM2.5 FRM monitors was 0.91609. This linear regression was examining all paired PM2.5

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 μg/m3 shown in 

Figure 11, the comparison of all Rossville and Siskin Drive PM2.5 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 PM2.5 FRM sampler collected a sample of 

48.7 μg/m3

. Both samples are high, however, this type of situation could be contributing to the 

slight difference in data and R2

 value of 0.8386. Even with this occasional difference in data, the 

linear regression between the Rossville and Siskin Drive PM2.5 FRM data is relatively tight, with 

most data points following the regression line. 

The next highest R2

 value was derived from the linear regression comparison between the 

Rossville and the Maxwell Road/Tombras Avenue PM2.5 FRM monitors. The R2

 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 and Maxwell Road/Tombras Avenue PM2.5 FRM data. On 

November 2, 2000 at the Rossville site, the value was 48.7 μg/m3 and at the Maxwell 

Road/Tombras Avenue site the value was 62.1 μg/m3

. This linear regression was comparing all 

paired PM2.5 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 PM2.5 FRM data 

follow the regression line, with few data points outside the line. 

The remaining R2

 values ranged from 0.6039 to 0.7962. These R2 values are relatively high 

overall. The lowest R2 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 PM2.5 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 PM2.5 FRM data and the Rossville and Maxwell 

Road/Tombras Avenue PM2.5 FRM data were plotted and analyzed using SigmaStat. These 

comparisons were made on the paired PM2.5 FRM data between the Rossville and the Siskin 

Drive sites, and on the paired PM2.5 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 PM2.5 FRM data and ‘Col 2’ is Siskin Drive PM2.5 FRM data. The 

mean for the Rossville PM2.5 FRM data was 14.831 μg/m3

, with standard deviation of 7.428 

μg/m3

, standard error of 0.326 μg/m3. The Rossville site’s maximum value was 48.7 μg/m3, 

median value of 13.6 μg/m3

, 25% of 9.6 μg/m3, and 75% of 18.3 μg/m3. The mean for the Siskin 

Drive PM2.5 FRM data was 14.469 μg/m3

, with standard deviation of 7.669 μg/m3, standard error 

of 0.337 μg/m3

. The Siskin Drive site’s maximum value was 71.6 μg/m3, median value of 13.1 

μg/m3

, 25% of 9.2 μg/m3, and 75% of 17.9 μg/m3. All data from January 1, 2000 to December 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 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 Siskin Drive PM2.5 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 PM2.5 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 PM2.5 FRM data. The top end of the box defines the 75th

percentile and the lower end of the box defines the 25th percentiles. The line in the middle of the 

box is the median. The error bars define the 10th and 90th percentiles. Column 1 is Rossville 

PM2.5 FRM data, and Column 2 is Siskin Drive PM2.5 FRM data. The data shown in this way 

appears to be almost identical, with the exception of the maximum 71.6 μg/m3 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 μg/m3

, also 

collected on November 2, 2000. The majority of data points for both sites appear to be between 

about 1 and 35 μg/m3

. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 28

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

XData

Column: 1 Column: 2

Y Axis

0

20

40

60

80

Figure 16: Box Plot of Rossville and Siskin Drive PM2.5 FRM Data Produced in SigmaStat 

Using SigmaStat, a Mann-Whitney Rank Sum Test was performed on the Rossville and Siskin 

Drive PM2.5 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 PM2.5 FRM data and ‘Col 3’ is Maxwell 

Road/Tombras Avenue PM2.5 FRM data. The mean for the Rossville PM2.5 FRM data was 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 29

14.963 μg/m3, with standard deviation of 7.538 μg/m3, standard error of 0.342 μg/m3. The 

maximum value was 48.7 μg/m3

, median value of 13.8 μg/m3, 25% of 9.7 μg/m3, and 75% of 

18.9 μg/m3. The mean for the Maxwell Road/Tombras Avenue PM2.5 FRM data was 14.933 

μg/m3

, with standard deviation of 7.660 μg/m3, standard error of 0.347 μg/m3. The maximum 

value was 62.1 μg/m3

, median value of 13.55 μg/m3, 25% of 9.6 μg/m3, and 75% of 18.2 μg/m3. 

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 PM2.5 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 PM2.5 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 PM2.5

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 PM2.5 FRM data. The top end of the box 

defines the 75th percentile and the lower end of the box defines the 25th percentiles. The line in 

the middle of the box is the median. The error bars define the 10th and 90th percentiles. Column 

2 is Rossville PM2.5 FRM data, and Column 3 is Maxwell Road/Tombras Avenue PM2.5 FRM 

data. The data shown in this way appears to be almost identical, with the exception of the 

maximum 62.1 μg/m3 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 μg/m3, also collected on November 2, 2000. 

The majority of data points for both sites appear to be between about 1 and 35 μg/m3

. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 30

XData

Column: 2 Column: 3

Y 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 PM2.5 FRM Data 

Produced in SigmaStat 

A Mann-Whitney Rank Sum Test was also performed on the Rossville and Maxwell 

Road/Tombras Avenue PM2.5 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 PM2.5 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 25th to 75th percentile 

range of data. With all three sites, this appears to be around 10 to 20 μg/m3

. The 10th percentile 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 31

is around 8 μg/m3 and the 90th percentile is around 25 μg/m3. Further, most of the data that is 

outlying this 10th and 90th percentile is grouped primarily in the same areas. The majority of the 

outlying data points fall close to the 10th and 90th 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 PM2.5 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 guidance tool for analyzing the PM2.5 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 PM2.5. 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 PM2.5 speciation data, more analyses were performed on the PM2.5 speciation data. 

Pearson Product-Moment Correlations, R2 values with linear regressions, quarterly percent 

differences, quarterly absolute differences, and quarterly percent contributions were examined 

on select PM2.5 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 PM2.5 

speciation data. With each analysis, the procedures and results are discussed below. 

The timeframe for comparison for the Pearson Product-Moment Correlations, R2 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 PM2.5 

speciation samplers collect samples on a one in six day sampling schedule, and collect over 50 

different PM2.5 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 PM2.5 Speciation Data 

The following table shows the Pearson Product-Moment Correlations on select PM2.5 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 PM2.5 species were selected for their common 

occurrence in PM2.5 speciation samples. The PM2.5 species evaluated were organic carbon, 

elemental carbon, sulfate, ammonium ion, total nitrate, aluminum, silicon, and potassium. The 

aluminum and silicon species are part of the crustal group.
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 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 R2 Values of PM2.5 Speciation Data 

A scatter plot and corresponding R2 value were produced on the PM2.5 speciation data collected 

at the Rossville and Siskin Drive sites. The following graphs show the information for the same 

PM2.5 species as listed above. These PM2.5 species include organic carbon, elemental carbon, 

sulfate, ammonium ion, total nitrate, aluminum, silicon, and potassium. Following the graphs is a 

summary table of the R2

 values produced from the linear regressions. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 33

Organic Carbon

y = 0.9975x

R2

 = 0.7347

0

5

10

15

20

0 2 4 6 8 10 12 14

Siskin Drive

Rossville

Figure 18: Select PM2.5 Speciation Data Scatter Plots (Organic Carbon) 

Elemental Carbon

y = 0.784x

R2

 = 0.5333

0

0.5

1

1.5

2

2.5

0 0.5 1 1.5 2 2.5 3

Siskin Drive

Rossville

Figure 19: Select PM2.5 Speciation Data Scatter Plots (Elemental Carbon) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 34

Sulfate

y = 0.9679x

R2

 = 0.9744

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8 10 12 14 16 18

Siskin Drive

Rossville

Figure 20: Select PM2.5 Speciation Data Scatter Plots (Sulfate) 

Ammonium Ion

y = 0.8991x

R2

 = 0.892

0

1

2

3

4

5

0123456

Siskin Drive

Rossville

Figure 21: Select PM2.5 Speciation Data Scatter Plots (Ammonium Ion) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 35

Total Nitrate

y = 0.7858x

R2

 = 0.8621

0

1

2

3

4

5

6

7

01234567

Siskin Drive

Rossville

Figure 22: Select PM2.5 Speciation Data Scatter Plots (Total Nitrate) 

Aluminum

y = 0.9662x

R2

 = 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 Drive

Rossville

Figure 23: Select PM2.5 Speciation Data Scatter Plots (Aluminum) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 36

Silicon

y = 0.9039x

R2

 = 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 Drive

Rossville

Figure 24: Select PM2.5 Speciation Data Scatter Plots (Silicon) 

Potassium

y = 1.4926x

R2

 = 0.8496

0

0.5

1

1.5

2

2.5

0 0.2 0.4 0.6 0.8 1 1.2

Siskin Drive

Rossville

Figure 25: Select PM2.5 Speciation Data Scatter Plots (Potassium) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 37

R2 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 R2

 Values 

Of the select PM2.5 species examined between the Rossville and Siskin Drive sites, the R2

 value 

between sulfate concentrations corresponds with the highest Pearson Product-Moment 

Correlation and shows a very high R2

 value, 0.9744. Almost all the data pairs of sulfate 

concentrations are on the line of regression. The high R2

 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 R2

 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 R2

 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 PM2.5 species 

examined for both the Rossville and Siskin Drive sites. The sulfate concentrations were as high 

as 16.5 μg/m3 for the paired data, and the R2

 value was 0.9744. The higher concentrations of 

sulfate could be attributing the stronger R2

 value. The lowest R2 value of 0.5333 was with the 

elemental carbon data. With the paired data of elemental carbon, the highest concentration was 

only 2.79 μg/m3

. The majority of the elemental carbon data points were below 1 μg/m3. For the 

aluminum linear regression, the R2

 value was 0.6674. The highest concentration of the paired 

aluminum data was even lower, with 0.612 μg/m3

. The majority of the data points were below 

0.1 μg/m3

. 

The remaining PM2.5 species examined have R2 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 

μg/m3

. The R2 value of organic carbon was 0.7347. The majority of the paired organic carbon 

data points were between 1 μg/m3

 and 10 μg/m3. The highest concentration of paired 

ammonium ion data was 5.06 μg/m3

. The R2 value of the linear regression for ammonium ion 

was 0.8920. The majority of the paired ammonium ion data points were between 0.3 μg/m3

 and 

3 μg/m3

. Total nitrate’s highest concentration of paired data was 6.59 μg/m3. The R2 value of 

total nitrate linear regression was 0.8621. The majority of the paired total nitrate data points 

were between 0.1 μg/m3

 and 2 μg/m3. The highest concentration of paired silicon data was 1.66 

μg/m3

. The R2 value of silicon data linear regression was 0.8980. The majority of the paired 

silicon data points were between 0 μg/m3

 and 0.2 μg/m3. Potassium’s highest concentration of 

paired data points was 2.15 μg/m3

. The R2 value of the linear regression for potassium data was 

0.8496. The majority of the paired potassium data points were between 0 μg/m3

 and 0.2 μg/m3. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 38

2.6.3 Percent Differences of PM2.5 Speciation Data 

In order to examine the PM2.5 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 PM2.5 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 PM2.5 

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 Siskin 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 μg/m3 and the Siskin Drive site’s 

concentration was 4.46 μg/m3

. If these data points were removed and the percent difference 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 μg/m3

 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 μg/m3 and Rossville sampled 18.1 μg/m3

. 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 μg/m3

 for Siskin Drive and 2.15 μg/m3 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 PM2.5 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 μg/m3

 range, with several samples shown as 0 

μg/m3

. 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 μg/m3 for the 

Siskin Drive site and 0.016509 μg/m3 for the Rossville site. This was only a difference of 0.009 

μg/m3 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 μg/m3 for the Siskin 

Drive site and 0.0065 μg/m3 for the Rossville site. This was only a difference of 0.0044 μg/m3

. Of 

the comparable aluminum data points for the second quarter of 2005, there was only one value 

detected above 0 μg/m3 at the Siskin Drive site and six data points detected above 0 μg/m3 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 μg/m3 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 the 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 are primarily measured at concentrations below 1 

μg/m3

. Ammonium ion is predominantly measured at concentrations below 2 μg/m3. Silicon is 

measured at even lower concentrations, primarily below 0.2 μg/m3

. 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 PM2.5 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 PM2.5

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 PM2.5 Speciation Data, 2005-2008

-30

-20

-10

0

10

20

30

Quarter

Percent Difference

Organic Carbon Elemental Carbon Sulfate Ammonium Ion

Total Nitrate Aluminum Silicon Potassium

Figure 26: Quarterly PM2.5 Speciation Percent Differences for Rossville and Siskin Drive 

Sites 

The above graph shows the quarterly percent differences for the select species of PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 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’ PM2.5 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 PM2.5 Speciation Data between 

Rossville and Siskin Drive Sites 

The above absolute differences between the quarterly PM2.5 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 differences 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 μg/m3 at the Siskin 

Drive site and six data points detected above 0 μg/m3 at the Rossville site. 

The following graph displays the quarterly absolute differences for the select species of PM2.5

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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 42

Quarterly Absolute Differences of Select PM2.5 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

2005-2

2005-3

2005-4

2006-1

2006-2

2006-3

2006-4

2007-1

2007-2

2007-4

2008-1

2008-2

2008-3

2008-4

Quarter

Absolute Difference

Organic Carbon Elemental Carbon Sulfate Ammonium Ion

Total Nitrate Aluminum Silicon Potassium

Figure 27: Quarterly PM2.5 Speciation Absolute Differences for Rossville and Siskin Drive 

Sites 

The above graph shows the quarterly absolute differences for the select species of PM2.5 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 μg/m3 

for the Rossville site and 5.87 μg/m3 for the Siskin Drive site for that quarter. 

2.6.4 Percent Contribution of PM2.5 Speciation Data

The PM2.5 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, ammonium ion, total nitrate, aluminum, silicon and 

potassium were examined. As a first examination of the PM2.5 speciation data, each select PM2.5 

species was compared independently of the other site. The data was not paired between the 

Rossville and Siskin Drive sites. A contribution of each PM2.5 species was calculated as part of 

the whole PM2.5 speciation mass sample for each site independently of the other site’s data. A 

quarterly average of each select PM2.5 species was calculated, and a quarterly average of the 

PM2.5 speciation mass was calculated. Then each PM2.5 species was calculated as part of the 

PM2.5 speciation mass reading to determine the percent contribution of that PM2.5 species to the 

total PM2.5 speciation mass reading. The following tables summarize that data. The first table 

shows the percent contribution of the PM2.5 speciation data at the Rossville site. The second 

table shows the percent contribution of the PM2.5 speciation data at the Siskin Drive site. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 43

Percent Contribution of 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 28.75 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 (%) 

YearQuarter

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 the 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 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 PM2.5 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 PM2.5 speciation data independently at 

each the Rossville and Siskin Drive sites, the PM2.5 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 PM2.5 species was 

paired when both the Rossville and Siskin Drive sites collected data. Then each of the PM2.5 

species was paired with the PM2.5 speciation mass readings. A percent contribution was 

calculated for each quarter when the pairs of PM2.5 species matched the pairs of PM2.5

speciation mass readings. This process was performed in an effort to ensure the percent 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 speciation 

data at the Rossville site. The second table shows the percent contribution of the PM2.5

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 PM2.5 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 PM2.5 Speciation Data at Siskin Drive 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 46

In comparing the PM2.5 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 

PM2.5 species had data collected, but there was not a PM2.5 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 PM2.5

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 PM2.5 speciation data. 

Aluminum, silicon, and potassium remained the lowest contributors to the overall PM2.5 

speciation data. 

2.6.5 Sources of PM2.5 Speciation Data 

In order to thoroughly analyze the Rossville PM2.5 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 PM2.5. In addition to analyzing the Pearson ProductMoment correlations, linear regressions, R2

 values, percent differences, absolute differences, 

and percent contributions of select PM2.5 speciation data, an analysis of sources of PM2.5 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 PM2.5 in 

Walker County, Georgia. However, there is a Title V Source in Walker County, Georgia that is a 

major source for sulfur dioxide (SO2), with minimal particulate matter (PM) emissions. The SO2

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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5. This facility’s PM2.5 emissions are 52.191 tons per year. It is located 

9.75 miles from the Rossville site. The second largest PM2.5 source has 14.55 tons per year. It is 

located 5.75 miles from the Rossville site. The largest source of PM2.5 is also the largest source 

of SO2 with 828.45 tons per year. The second largest source of PM2.5 is also the second largest 

source of SO2, with 349 tons per year source of SO2. The next largest source of SO2 is 31.19 

tons per year. All other direct sources of PM2.5 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 PM2.5 or SO2 produced would be 

greater in the Hamilton County, TN area than in the Walker County, GA area. The largest 

source of SO2 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 PM2.5 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 R2

 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 R2

 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 PM2.5 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 Protection 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 runs, 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 in 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 (PM2.5) Observations from 

2005 to 2008 at Rossville, GA 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 49

 Factor Name Percentage Ranking WDWE High 

Season 

Low 

Season 

1 2nd 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 PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 50

• Siskin Drive (2005-2008)

Figure 31: PMF Analysis Results of Speciated Fine Aerosol (PM2.5) 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 2nd 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 2nd 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 PM2.5. 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 the 

Siskin 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 PM2.5 speciation sections, sulfate showed a very strong relationship 

between the Rossville site and Siskin Drive site data. With the analysis of the select PM2.5

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 R2

 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 PM2.5 collected at the Rossville (38.3%) and Siskin 

Drive (37.2%) sites. These analyses were performed to verify that the PM2.5 data meets the 

Appendix N regulation used as guidance for this document. Both the Rossville and Siskin Drive 

sites are principally affected by sulfate sources. 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 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 

(PM2.5) concentrations. The observed corresponding relationship then between the PM2.5 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 PM2.5. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 53

Figure 32: Map of Terrain Between Sites 

In the recorded nine-year time frame (2000-2008), PM2.5 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. 30th, 2004, both Rossville and Siskin Drive 

sites measured a 24-hr averaged value of 22.9 μg/m3

 and Maxwell Road/Tombras Avenue 

averaged 23.2 μg/m3 under the influence of a weakening surface to upper level ridge positioned 

over the southeast. Surface analysis at 12Z on the 30th 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 showed 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 PM2.5 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 μg/m3

, 30.7 μg/m3, and 31.2 

μg/m3

, respectively. A third case of PM2.5 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/m3

, Siskin Drive recorded a concentration of 26.7 

μg/m3

, and Maxwell Road/Tombras Avenue recorded a concentration of 25.6 μg/m3. 

Meteorologically speaking, the above cases all showed that all three sites were under similar 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 analysis for various time periods would show good 

positive correlation in meteorological conditions and PM2.5 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 meso-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 Rossville 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 PM2.5

concentrations. 

2.8 Comparison of All Rossville and Siskin Drive PM2.5 FRM Data 

The Rossville PM2.5 FRM monitor showed the strongest relationship with the Siskin Drive and 

Maxwell Road/Tombras Avenue PM2.5 FRM monitors. As an additional analysis, each of the 

paired data points between the Rossville and Siskin Drive PM2.5 FRM monitors and between the 

Rossville and Maxwell Road/Tombras Avenue PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 55

The first three graphs are the comparison of the Rossville PM2.5 FRM monitor and the Siskin 

Drive PM2.5 FRM monitor. The Rossville PM2.5 FRM data is shown in blue and the Siskin Drive 

PM2.5 FRM data is shown in yellow. 

Rossville and Siskin Drive 2000-2002

0

10

20

30

40

50

60

70

80

1/1/2000

3/1/2000

5/1/2000

7/1/2000

9/1/2000

11/1/2000

1/1/2001

3/1/2001

5/1/2001

7/1/2001

9/1/2001

11/1/2001

1/1/2002

3/1/2002

5/1/2002

7/1/2002

9/1/2002

11/1/2002

Date

Concentration (ug/m3

)

Rossville Siskin Drive

Figure 33: Comparison of All Rossville and Siskin Drive PM2.5 FRM Data Collected from 

2000 through 2008 at Rossville and Siskin Drive (2000-2002) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 56

Rossville and Siskin Drive 2003-2005

0

5

10

15

20

25

30

35

40

45

50

1/3/20033/3/20035/3/20037/3/2003

9/3/2003

11/3/2003

1/3/20043/3/20045/3/20047/3/20049/3/2004

11/3/2004

1/3/2005

3/3/20055/3/2005

7/3/2005

9/3/2005

11/3/2005

Date

Concentration (ug/m3

)

Rossville Siskin Drive

Figure 34: Comparison of All Rossville and Siskin Drive PM2.5 FRM Data Collected from 

2000 through 2008 at Rossville and Siskin Drive (2003-2005) 

Rossville and Siskin Drive 2006-2008

0

5

10

15

20

25

30

35

40

45

50

1/5/20063/5/20065/5/20067/5/20069/5/2006

11/5/2006

1/5/20073/5/2007

5/5/2007

7/5/2007

9/5/2007

11/5/2007

1/5/2008

3/5/2008

5/5/20087/5/2008

9/5/2008

11/5/2008

Date

Concentration (ug/m3

)

Rossville Siskin Drive

Figure 35: Comparison of All Rossville and Siskin Drive PM2.5 FRM Data Collected from 

2000 through 2008 at Rossville and Siskin Drive (2006-2008) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 57

The Rossville PM2.5 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 PM2.5 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 2007 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 PM2.5 FRM data from the Rossville site seems to 

track the PM2.5 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 sites on January 1, 2000. The Siskin Drive site shows a PM2.5 concentration of 41.7 μg/m3 

and the Rossville site reports 43.1 μg/m3. Both sites have concentrations remaining around 10 

μg/m3

 to 30 μg/m3 following the same fluctuation until October 27, 2000 when both sites spike. 

The Rossville site collected a concentration of 48.3 μg/m3

 while the Siskin Drive site collected 

48.6 μg/m3

. Then on November 2, 2000 both sites continue to spike. The Siskin Drive site 

reports a PM2.5 concentration of 71.6 μg/m3

 and the Rossville site reports 48.7 μg/m3. 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 μg/m3 and the Siskin Drive site reports 5 

μg/m3

. There is a smaller spike on November 15, 2001, with Rossville reporting a concentration 

of 34 μg/m3

 and Siskin Drive reporting 47.5 μg/m3. There is an obvious pattern from May 8, 

2002 until October 17, 2002, in Figure 33, where both sites show almost the exact same PM2.5 

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 (μg/m3

). 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 FRM Data Trend 

This pattern continues in 2003. In Figure 34, on March 9, 2003, the Siskin Drive site showed a 

low PM2.5 concentration of 3.9 μg/m3 and the Rossville site also showed a low 2.9 μg/m3

. Then 

on March 15, 2003, the Siskin Drive site spikes to 31 μg/m3

 while the Rossville site spikes to 

30.7 μg/m3

. With the next pair of data, on March 21, 2003 both sites collected 10.1 μg/m3. On 

June 26, 2003 both sites show a spike in the data. The Rossville site samples a PM2.5

concentration of 46.9 μg/m3 and the Siskin Drive site samples 41.4 μg/m3

. Then on July 2, 2003, 

both sites dip down to PM2.5 concentrations of 3 μg/m3

. 

Another example of the similarity in the PM2.5 FRM data is shown in Figure 34, with the 2005 

data. On August 8, 2005, the Rossville site collected a PM2.5 concentration of 8.2 μg/m3

, and the 

Siskin Drive site collected 8 μg/m3

. On August 14, 2005 both sites had a slight increase in 

concentration. The Rossville site sampled a PM2.5 concentration of 20.9 μg/m3

 and the Siskin 

Drive site sampled 20.1 μg/m3

. Both sites’ concentrations remained relatively steady on August 

20, 2005. The Rossville sampled a PM2.5 concentration of 16.9 μg/m3

 and Siskin Drive sampled 

18.3 μg/m3

. Then on August 26, 2005 both sites showed a spike in concentration. The Rossville 

site sampled 32.6 μg/m3

 while the Siskin Drive site sampled 33.4 μg/m3. There was a decrease 

in concentration on September 7, 2005 at both sites. The Rossville site sampled 16.5 μg/m3 and 

the Siskin Drive site sampled 15.9 μg/m3

. Then on September 13, 2005, both site’s 

concentrations spiked up again. The Rossville site collected a PM2.5 concentration of 36.1 μg/m3 

and the Siskin Drive site collected 36.3 μg/m3. 

In Figure 35, there is another example of both sites showing the same fluctuating pattern with 

almost identical data. On May 21, 2007 the Rossville site sampled a PM2.5 concentration of 13.5 

μg/m3

 while the Siskin Drive site sampled 13.8 μg/m3. On May 24, 2007 the Rossville site 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 59

sampled 14.8 μg/m3 and the Siskin Drive site sampled 14.4 μg/m3. Then on May 27, 2007 both 

sites spiked. Rossville sampled a PM2.5 concentration of 43.9 μg/m3

 and Siskin Drive site 

sampled 43.2 μg/m3. On May 30, both sites sampled lower concentrations. The Rossville site 

collected 21.6 μg/m3

 and the Siskin Drive site collected 22.3 μg/m3. On June 2, 2007 both sites 

showed slightly higher concentrations. Rossville sampled 29.8 μg/m3

and Siskin Drive sampled 

30.7 μg/m3. Then on June 5, 2007, both sites showed even more of a drop in concentration. The 

Rossville site collected 9.3 μg/m3 while the Siskin Drive site collected 8.2 μg/m3

. 

The next three graphs display the comparison of the Rossville PM2.5 FRM monitor and the 

Maxwell Road/Tombras Avenue PM2.5 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 PM2.5 FRM data is shown in blue and the Maxwell 

Road/Tombras Avenue PM2.5 FRM data is shown in red. 

Rossville and Maxwell Road/Tombras Avenue 2000-2002

0

10

20

30

40

50

60

70

1/1/2000

3/1/2000

5/1/2000

7/1/2000

9/1/2000

11/1/2000

1/1/2001

3/1/2001

5/1/2001

7/1/2001

9/1/2001

11/1/2001

1/1/2002

3/1/2002

5/1/2002

7/1/2002

9/1/2002

11/1/2002

Date

Concentration (ug/m3)

Maxwell Rd/Tombras Ave

Rossville

 

Figure 36: Comparison of All Rossville and Maxwell Road/Tombras Avenue PM2.5 FRM 

Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2000-2002) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 60

Rossville and Maxwell Road/Tombras Avenue 2003-2005

0

5

10

15

20

25

30

35

40

45

50

1/3/2003

3/3/2003

5/3/2003

7/3/2003

9/3/2003

11/3/2003

1/3/2004

3/3/2004

5/3/2004

7/3/2004

9/3/2004

11/3/2004

1/3/2005

3/3/2005

5/3/2005

7/3/2005

9/3/2005

11/3/2005

Date

Concentration (ug/m3)

Maxwell Rd/Tombras Ave

Rossville

Figure 37: Comparison of All Rossville and Maxwell Road/Tombras Avenue PM2.5 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

1/5/2006

3/5/2006

5/5/2006

7/5/2006

9/5/2006

11/5/2006

1/5/2007

3/5/2007

5/5/2007

7/5/2007

9/5/2007

11/5/2007

1/5/2008

3/5/2008

5/5/2008

7/5/2008

9/5/2008

11/5/2008

Date

Concentration (ug/m3)

Maxwell Rd/Tombras Ave

Rossville

Figure 38: Comparison of All Rossville and Maxwell Road/Tombras Avenue PM2.5 FRM 

Data Collected from 2000 through 2008 at Rossville and Siskin Drive (2006-2008) 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 61

The Rossville PM2.5 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 PM2.5 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 PM2.5 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 similarities between the Rossville 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 Maxwell Road/Tombras Avenue sites had a spike on January 1, 2000. The 

Rossville site had a PM2.5 concentration of 43.1 μg/m3

 and the Maxwell Road/Tombras Avenue 

site had 53.3 μg/m3

. Both sites have concentrations remaining around 10 μg/m3 to 30 μg/m3, 

following the same fluctuation until October 27, 2000 when both sites spike. The Rossville site 

samples a PM2.5 concentration of 48.3 μg/m3

 while the Maxwell Road/Tombras Avenue site 

samples 49.5 μg/m3

. Then on November 2, 2000 both sites continue the spike in PM2.5 levels. 

The Maxwell Road/Tombras Avenue site reports a PM2.5 concentration of 62.1 μg/m3

 and the 

Rossville site reports 48.7 μg/m3

. 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 PM2.5 concentration of 3.3 μg/m3 and Maxwell Road/Tombras Avenue reports 

5 μg/m3

. There is a smaller spike in concentration on November 15, 2001, with Rossville 

reporting 34 μg/m3

 and Maxwell Road/Tombras Avenue reporting 45.5 μg/m3. 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 (μg/m3

). 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 FRM Data 

Trend 

This pattern continues in 2003. In Figure 37, on March 9, 2003, the Maxwell Road/Tombras 

Avenue site showed a low PM2.5 concentration of 4.5 μg/m3 and the Rossville site also showed a 

low 2.9 μg/m3

. Then on March 15, 2003, the Maxwell Road/Tombras Avenue site’s 

concentration spikes to 32.5 μg/m3

 while the Rossville site spikes to 30.7 μg/m3. Then on March 

21, 2003 both site’s concentrations drop. The Maxwell Road/Tombras Avenue samples 9.7 

μg/m3

 while the Rossville site samples 10.1 μg/m3. On June 26, 2003 both sites show a spike in 

the PM2.5 data. The Rossville site samples 46.9 μg/m3 and the Maxwell Road/Tombras Avenue 

site samples 44.3 μg/m3

. Then on July 2, 2003, both sites’ concentrations drop down. The 

Rossville site samples 3 μg/m3

 and the Maxwell Road/Tombras Avenue sites samples 3.2 

μg/m3

. 

Another example of the similarity in the PM2.5 FRM data is shown in Figure 37, with the 2005 

data. On August 8, 2005, both the Rossville and Maxwell Road/Tombras Avenue sites had low 

concentrations. The Rossville site sampled 8.2 μg/m3

, and the Maxwell Road/Tombras Avenue 

site sampled 8.4 μg/m3

. Then on August 14, 2005 there was an increase in PM2.5 concentrations 

at both sites. The Rossville site collected 20.9 μg/m3

 and Maxwell Road/Tombras Avenue 

collected 18.9 μg/m3

. On August 20, 2005, both site’s concentrations remained relatively steady. 

The Rossville site sampled 16.9 μg/m3

 and Maxwell Road/Tombras Avenue sampled 16.4 

μg/m3

. By August 26, 2005, both sites had increases in concentrations. The Rossville site 

sampled 32.6 μg/m3

 while the Maxwell Road/Tombras Avenue site sampled 28.2 μg/m3. There 

was a decrease in concentrations on September 7, 2005. The Rossville site sampled a PM2.5

concentration of 16.5 μg/m3 and Maxwell Road/Tombras Avenue sampled 15.7 μg/m3

. Then on 

September 13, 2005 both site’s concentrations spiked. The Rossville site collected 36.1 μg/m3 

and the Maxwell Road/Tombras Avenue site collected 35.8 μg/m3. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 63

In Figure 38, there is another example of both sites showing the same fluctuating pattern with 

almost identical PM2.5 data. On May 21, 2007 the Rossville site’s concentration was 13.5 μg/m3

while the Maxwell Road/Tombras Avenue site sampled 13.2 μg/m3. On May 24, 2007 both site’s 

concentrations remained steady. The Rossville site sampled 14.8 μg/m3

 and the Maxwell 

Road/Tombras Avenue site sampled 13.2 μg/m3

. Then on May 27, 2007 both site’s 

concentrations spiked. The Rossville site sampled a PM2.5 concentration of 43.9 μg/m3 and 

Maxwell Road/Tombras Avenue site sampled 45.1 μg/m3

. On May 30, both sites sampled lower 

concentrations. The Rossville site sampled 21.6 μg/m3

 and the Maxwell Road/Tombras Avenue 

site sampled 20.4 μg/m3

. On June 2, 2007 both sites showed higher concentrations. The 

Rossville site sampled a concentration of 29.8 μg/m3 and Maxwell Road/Tombras Avenue 

sampled 31.2 μg/m3

. Then on June 5, 2007, both sites showed even more of a drop in 

concentration. The Rossville site collected a PM2.5 concentration of 9.3 μg/m3 while the Maxwell 

Road/Tombras Avenue site collected 8.5 μg/m3

. 

Overall, both the comparisons of the Rossville PM2.5 FRM data to the Siskin Drive PM2.5 FRM 

data and the Maxwell Road/Tombras Avenue PM2.5 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 sites show similarities with their pattern of fluctuation and levels of PM2.5 concentration. 

Typically, when the levels of PM2.5 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 PM2.5 concentration, and when there 

is a drop in the PM2.5 concentration, all three sites show the drop in concentration. All three sites 

show the same trend in PM2.5 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 Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 64

The following table and Google Earth map were produced with the Removal Bias tool. An 

analysis was run on the PM2.5 FRM data. Rossville was removed from the network of PM2.5 FRM 

data in the database. The tool calculates the PM2.5 FRM data as if the Rossville site never 

existed. The Removal Bias tool shows that the Rossville site’s PM2.5 FRM data had an average 

bias of –0.2 μg/m3

, with a p-value of 0.647944. This means that the interpolation used to create 

the estimated PM2.5 FRM value is –0.2 μg/m3 different from the actual PM2.5 FRM value 

measured at the Rossville site. The tool shows that this difference (-0.2 μg/m3

) between the 

interpolated and measured PM2.5 FRM concentrations is not statistically significant. The PM2.5

data collected at the neighboring sites and used to create the estimate was not significantly 

different from the Rossville site’s actual PM2.5 concentrations. This is a useful tool to show that 

the PM2.5 data collected at Rossville’s neighboring sites could be substituted since the PM2.5 

data collected at those neighboring sites is not significantly different. 

As stated in the description above, the negative bias indicates that the estimated PM2.5 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 

PM2.5 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 PM2.5 FRM data being collected 

at the Rossville site compared to the interpolated concentration calculated from the ten 

neighboring sites. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 November 13, 2007, the Rossville site (AQS ID 13-295-

0002) in Walker County, Georgia did not collect PM2.5 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 development of this document is the number of PM2.5 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, and 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 66

the most recent 3-year design value is >/=85% of any PM2.5 NAAQS, there should be two PM2.5 

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 PM2.5 monitors. There are currently four PM2.5 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 PM2.5 monitors in the 

Chattanooga, TN-GA MSA collecting PM2.5 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 PM2.5, 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 PM2.5 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 PM2.5 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 PM2.5 data, data from two 

other sites within the same Chattanooga-Tennessee-Georgia MSA was analyzed for potential 

substitution of that PM2.5 FRM data. This analysis was done in order to eventually calculate a 

PM2.5 design value for the Rossville site. 

The spatial averaging rule found in 40CFR50, Appendix N is a good foundation for 

understanding the significance PM2.5 statistical tests. The spatial averaging rule has a number of 

strict statistical tests that must be met in order to spatial average PM2.5 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 PM2.5... 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 PM2.5 data 

generally met the spatial averaging tests since 2000. 

This document has shown a number of analyses done on three of the PM2.5 sites within the 

Chattanooga, TN-GA MSA. A comparison was made between the Rossville site and the 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 67

Maxwell Road/Tombras Avenue, and the Siskin Drive sites. In addition to examining the above 

criteria regarding the PM2.5 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 R2

 values 

were evaluated. A box plot was graphed and displayed in the document. Pearson ProductMoment Correlation, linear regressions, R2

 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 PM2.5 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 Rossville-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 Drive 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 Correlations derived from the different types of data 

(PM2.5 FRM data and PM2.5 speciation mass), it appears that the Rossville PM2.5 FRM and Siskin 

Drive PM2.5 FRM complete datasets from 2000 to 2008 show the strongest correlation, 0.91609. 

The correlation between the Rossville PM2.5 FRM and Maxwell Road/Tombras Avenue PM2.5

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 PM2.5 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 PM2.5

FRM quarterly correlations above 0.9 for the Rossville and Maxwell Road/Tombras Avenue 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 FRM annual means data for 

Rossville compared to the Maxwell Road/Tombras Avenue and Siskin Drive sites showed 

differences less than 10% for each year. 

All of the means of the total 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 Avenue sites were below the 10% 

used as guidance. The Rossville and Siskin Drive PM2.5 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 PM2.5 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 PM2.5 speciation mass and Siskin Drive PM2.5 FRM data comparison March 23, 2005 

to March 26, 2009 and had a 9.19% difference. The Rossville PM2.5 speciation mass and Siskin 

Drive PM2.5 speciation mass data comparison was from March 23, 2005 to December 26, 2008 

and had a –3.57% difference. The Rossville PM2.5 speciation mass and Maxwell Road/Tombras 

Avenue PM2.5 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 comparisons 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 R2

 values derived from the linear regressions, the Rossville and 

Siskin Drive PM2.5 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 PM2.5 FRM monitors was 0.91609. The next highest R2

 value was derived from the linear 

regression comparison between the Rossville and the Maxwell Road/Tombras Avenue PM2.5

FRM monitors. The R2

 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 was 0.91362. These linear regressions were 

examining all paired PM2.5 FRM data collected from January 1, 2000 to December 29, 2008. 

In order to further explore the comparison of PM2.5 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 PM2.5 FRM 

datasets with SigmaStat. The results show that the mean, standard deviation, standard error, 

median, 25%, and 75% of the data at the Rossville, Siskin Drive, and Maxwell Road/Tombras 

Avenue are almost identical. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 69

Since the Rossville and Siskin Drive sites showed one of the strongest relationships and both 

sites collect PM2.5 speciation data, more analyses were performed on select PM2.5 speciation 

data. The PM2.5 species evaluated were organic carbon, elemental carbon, sulfate, ammonium 

ion, total nitrate, aluminum, silicon, and potassium. In the PM2.5 speciation analyses, sulfate 

showed a very strong relationship between the Rossville site and Siskin Drive site data. With the 

analysis of the select PM2.5 speciation data, the Pearson Product-Moment Correlation of the 

overall dataset from 2005 to 2008, the linear regression and R2

 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 R2

 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 PM2.5 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 PM2.5 speciation analyses, a source apportionment model was 

performed on the PM2.5 speciation data. This PMF model shows that sulfate is the largest 

component contributing to the total PM2.5 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 PM2.5 data meets the regulation 

(40CFR50, Appendix N) used as guidance for this document. 

To show that the PM2.5 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 

(PM2.5) concentrations. The observed corresponding relationship then between the PM2.5 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 PM2.5 concentrations. 

With the line graph comparisons of the Rossville PM2.5 FRM data to the Siskin Drive PM2.5 FRM 

data and the Maxwell Road/Tombras Avenue PM2.5 FRM data, both evaluations show very 

close agreement. All three sites show similarities with their pattern of fluctuation and levels of 

PM2.5 concentration. Typically, when the levels of PM2.5 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 PM2.5

concentration, and when there is a drop in the PM2.5 concentration, all three sites show the drop 

in concentration. All three sites show the same trend in PM2.5 FRM data. 

The Removal Bias tool shows that this difference (-0.2 μg/m3

) between the interpolated and 

measured PM2.5 FRM concentrations is not statistically significant. The PM2.5 data collected at 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 70

the neighboring sites and used to create the estimate was not significantly different from the 

Rossville site’s actual PM2.5 concentrations. This shows that the PM2.5 data collected at 

Rossville’s neighboring sites could be substituted since the PM2.5 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 the 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 site had very comparable historical data with 

both the Siskin Drive site and the Maxwell Road/Tombras Avenue site. Comparisons between 

the Rossville site and both the Siskin Drive 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 R2

 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 PM2.5 FRM data was substituted for the Rossville site PM2.5 FRM data in 

three different scenarios for thoroughness. 

For the following Siskin Drive PM2.5 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 PM2.5 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 PM2.5 FRM data substituted for the missing Rossville PM2.5 FRM data for 

every data point from June 12 to November 13, 2007, the weighted annual mean would be 

15.44 μg/m3 for 2007.The following table shows the calculation of the 2006-2008 design value 

for the Rossville site, with the Siskin Drive PM2.5 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 

μg/m3

. 

Calculation of Rossville PM2.5 Annual Design 

Value with 2007 Siskin Drive Data Substituted (μg/m3)

2006 14.45 

2007 15.44* 

2008 12.48 

2006-2008 Design Value 14.1 

 *calculated manually 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 71

The following table shows the calculation of the 2006-2008 design value for the Rossville site, 

with the Siskin Drive PM2.5 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 μg/m3

. 

Calculation of PM2.5 Annual Design 

with Siskin Drive Substituted for 3rd Quarter and Part of 4th Quarter 

Data from 2006-2008 (μg/m3)

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 PM2.5 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 μg/m3

. 

Calculation of PM2.5 Annual Design 

with Siskin Drive Substituted for 3rd Quarter Only Data from 2006-

2008 (μg/m3)

2006 14.45 

2007 15.29* 

2008 12.48 

2006-2008 Design Value 14.1 

*calculated manually 

With all three scenarios of Siskin Drive PM2.5 FRM data substitution, the annual mean for 2007 

was above the standard of 15.0 μg/m3

. Even with the substituted 2007 PM2.5 FRM data above 

the 15.0 μg/m3 standard, all three scenarios of substitution showed a three-year design value 

below 15.0 μg/m3

. 

For the following Maxwell Road/Tombras Avenue PM2.5 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 the Rossville site on May 27 and concurred by EPA. 

There were no exceptional event days concurred 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 PM2.5 FRM data substituted for the missing Rossville 

PM2.5 FRM data for every data point from June 12 to November 13, 2007, the weighted annual 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 72

mean would be 15.22 μg/m3 for 2007. The following table shows the calculation of the 2006-

2008 design value for the Rossville site, with the Maxwell Road/Tombras Avenue PM2.5 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 μg/m3

. 

Calculation of Rossville PM2.5 Annual Design 

Value with 2007 Maxwell Road/Tombras Avenue Data Substituted 

(μg/m3)

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 PM2.5 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 μg/m3

. 

Calculation of PM2.5 Annual Design 

with Maxwell Road/Tombras Avenue Substituted for 3rd Quarter and 

Part of 4th Quarter Data from 2006-2008 (μg/m3)

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 PM2.5 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 μg/m3

. 

Calculation of PM2.5 Annual Design 

with Maxwell Road/Tombras Avenue Substituted for 3rd Quarter 

Only Data from 2006-2008 (μg/m3)

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 PM2.5 FRM data substitution, 

the annual mean for 2007 was above the standard of 15.0 μg/m3

. Even with the substituted 

2007 PM2.5 FRM data above the 15.0 μg/m3 standard, all three scenarios of substitution showed 

a three-year design value below 15.0 μg/m3

. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 Data Page 73

3.2 Spatial Averages 

As an alternative to substituting the PM2.5 FRM data from the Siskin Drive site or the Maxwell 

Road/Tombras Avenue site at the Rossville site, spatially averaging the PM2.5 FRM data was 

examined. To cover different possible ways of spatial averaging the PM2.5 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 PM2.5 annual means were taken directly from AQS. If spatial 

averaging is used to calculate the 2006-2008 PM2.5 annual design value, the result would be 

13.9 μg/m3

 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 PM2.5 Annual Design 

with Rossville, Siskin Drive, and Maxwell Road/Tombras Avenue 

Sites Unadjusted from AQS (μg/m3)

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 PM2.5 annual means were taken directly from AQS. If spatial averaging is 

used to calculate the 2006-2008 PM2.5 annual design value, the result would be 14.0 μg/m3

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 PM2.5 Annual Design 

with Siskin Drive and Maxwell Road/Tombras Avenue Sites 

Unadjusted from AQS (μg/m3)

2006 14.60 

2007 14.99 

2008 12.55 

2006-2008 Design Value 14.0 

The third scenario computes the spatial average 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 PM2.5 

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 PM2.5 annual design value, the result 

would be 14.0 μg/m3

 using unadjusted AQS values for only the Maxwell Road/Tombras 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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 PM2.5 Annual Design 

with Siskin Drive, Maxwell Road/Tombras Avenue Sites, and 

Rossville for 2006 and 2008 (μg/m3)

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 PM2.5 annual standard of 15.0 μg/m3

. The scenarios covered three year averages that 

included the Rossville site for the 2007 PM2.5 data, and that excluded the Rossville 2007 PM2.5 

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 PM2.5 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 PM2.5 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 the 

modified data substitution, and apply it to the design value calculation for the Chattanooga, TNGA MSA. 
Georgia Department of Natural Resources/EPD 5/5/2010 

Analysis of Rossville PM2.5 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