Attachment H 

Utility SO2 Correlations 
1 

Attachment H: Correlation of Local, State, and Regional SO2 Emissions with Monitored 

PM2.5 Concentrations in the Knoxville Region 

This attachment presents Tennessee’s analysis of emissions and ambient monitoring data to 

determine if any correlation exists between utility SO2 emissions and ambient monitored PM2.5

concentrations. Utility, State, and Regional emissions data for 1999-2006 were obtained from 

Acid Rain Program monitoring data. Emission trends for TVA’s Bull Run and Kingston plants, 

and Statewide emissions for Tennessee, are shown in Figure 1. 

Figure 1: Utility SO2 Emission Trends 

States were selected for a regional analysis based on EPA’s CAIR modeling results (all State 

with impact of ≥ 0.2 μg/m3

 on Knoxville PM2.5 concentrations). Since PM2.5 design values are 

based on a three-year average, average SO2 emissions were calculated for the same time period1. 

Tabulated emissions are shown in Table 1. Ambient PM2.5 three-year averages were based upon 

FRM monitor data from Knoxville-area monitors (Table 2). 

 

1

 In general, this document uses “three-year average” rather than “design value” to describe ambient PM2.5

concentrations because some of the monitors shown here did not have enough quarters of data to calculate a true 

design value. 
2 

Table 1: Acid Rain Program Emissions Data, Three-Year Averages 

3-Year Avg. SO2 Emissions (tons) 

3-Year Period Bull Run Kingston 

Bull Run + 

Kingston TN Total Region Total 

1999-2001 40,461 98,812 139,274 409,516 5,626,491 

2000-2002 42,937 88,271 131,208 374,021 5,207,694 

2001-2003 45,530 86,616 132,146 345,542 5,079,362 

2002-2004 39,554 81,539 121,092 326,615 5,090,458 

2003-2005 36,863 74,418 111,281 302,977 5,116,526 

2004-2006 31,375 62,247 93,623 276,334 4,964,058 

Data Source: US EPA Clean Air Markets Data and Maps (http://camddataandmaps.epa.gov) 

Regional States are: Alabama, Georgia, Illinois, Indiana, Kentucky, North Carolina, Ohio, Tennessee, and West Virginia. 

Table 2: PM2.5 3-Year Averages for Knoxville-Area FRM Monitors 

3-Year Period

PM2.5 3-Year Averages (μg/m3) 

47-093-

0028-1 

47-093-

1013-1 

47-093-

1017-1* 

47-093-

1020-1 

47-009-

0011-1 

47-145-

0004-1 

47-105-

0108-1 

All 

Monitors 

1999-2001 17.9 20 17.4 16.1 16.8 17.6 

2000-2002 16.4 16.9 17.9 17.1 15.6 15.3 16.5 

2001-2003 15.2 16.4 16.4 15.8 14.1 14.1 15.3 

2002-2004 14.5 14.9 15.7 15.1 13.9 13.6 15.5 14.7 

2003-2005 14.5 13.9 15.6 15.1 14.1 14.2 15.7 14.7 

2004-2006 15.2 15.6 15.2 14.1 14.5 15.3 15 

* Controlling monitor. 

Sulfur dioxide emissions were plotted against PM2.5 three-year averages for Knoxville-area 

monitors at the facility, State, and regional level to observe whether any linear trends could be 

observed (Figures 2 – 6). Monitoring data was plotted as the average of all Knoxville area 

monitors, plus the three individual monitors that were above 15.0 μg/m3 in 2006. 
3 

Figure 2: TVA Bull Run SO2 Chart 

Figure 3: TVA Kingston SO2 Chart 
4 

Figure 4: TVA Bull Run Plus Kingston SO2 Chart 

Figure 5: Tennessee Statewide SO2 Chart 
5 

Figure 6: Regional SO2 Chart 

For each chart, linear correlation coefficients were calculated to analyze the linearity of each data 

set (Table 3). In general, a linear relationship appears to exist between ambient PM2.5

concentrations and SO2 emissions, based on several metrics. Surprisingly, emissions from 

TVA’s Bull Run Fossil Plant did not appear to correlate well with ambient PM2.5 concentrations. 

The result was unexpected because the facility is located within the nonattainment area. 

Review of a line chart for Bull Run (Figure 7) suggests that the relationship at the controlling 

monitor is more linear if data from two years (1999 and 2000) are omitted from the analysis. 

Table 3 shows that this assumption is generally correct, although performance suffers at monitor 

47-093-0028-1. 

Table 3: Linear Correlation Coefficients 

47-093-0028-1 47-093-1017-1* 47-093-1020-1 All Monitors 

Bull Run 0.266 0.396 0.493 0.360 

Bull Run 

(2001-2006 Only) 0.024 0.863 0.731 0.441 

Kingston 0.707 0.828 0.800 0.773 

Bull Run + Kingston 0.609 0.738 0.746 0.686 

TN Total 0.838 0.922 0.912 0.891 

Region Total 0.880 0.942 0.814 0.894 

Correlation coefficients are calculated for three-year averages of SO2 emissions and three-year average ambient PM2.5 concentrations. 

* Controlling monitor. 
6 

Figure 7: TVA Bull Run Line Chart 

Figure 8: TVA Bull Run SO2 Chart with 1999 and 2000 Omitted