# Appendix C

Historic Air Quality Data

# TABLE OF CONTENTS

**I. Historic Fourth Highest 8-Hour Ozone Values (pp m) for the Charlotte-Gastonia-Rock Hill, NC-SC** 

**Nonattainment Area........................... .1** 

**Table C-1: Historic Fourth Highest 8-Hour Ozone V alues (ppm) for the Charlotte-Gastonia-Rock** 

**Hill, NC-SC Nonattainment Area...... ......1** 

**II. Historic 8-Hour Ozone Design Values (ppm) for the Charlotte-Gastonia-Rock Hill, NC-SC** 

**Nonattainment Area............... ......................2** 

**Table C-2: Historic 8-Hour Ozone Design Values (p pm) for the Charlotte-Gastonia-Rock Hill, NC** 

**SC Nonattainment Area.....................2 1** HISTORIC AIR QUALITY DATAI. Historic Fourth Highest 8-Hour Ozone Values (ppm) for the Charlotte-Gastonia-Rock Hill, NC-SC Nonattainment Area**8-hour running averages were calculated for each y ear (1994-2006) at each monitor in the Charlotte-Ga** **stonia-Rock Hill Nonattainment area. This was done by calculating 8-hour running average** **s from hourly data at each site in the area. After calculating the 8-hour running averages for** **each hour of the day, the maximum 8-hour ozone conc entrations were selected for each day at each site.** **Sorting by date and concentration gives the rankings of the maximum 8-hour ozone concentrat** **ions for each day of the year. The fourth highest 8-hour concentration was pulled out of** **each data set for each monitor. These concentratio ns are listed for each year at each monitor in Tabl** **e 1.**Table C-1:Historic Fourth Highest 8-Hour Ozone Values (ppm) for Charlotte-Gastonia-Rock Hill, NC-SC Nonattainment Area**Monitoring Sites County 1994 1995 1996 1997 1998 1999 2000 2001 2002** **2003 2004 2005 2006 Crouse Lincoln** 0.0880.0900.0840.0850.0900.0870.0940.0940.0950.089**0.074 0.082** **0.082 Arrowood Mecklenburg** 0.0870.0960.0990.0940.1040.1040.0870.0860.094**0.073 0.077** 0.085**0.080 County Line Mecklenburg** 0.0910.0910.0990.1010.1100.1030.1010.0990.1070.088**0.083**0.0900.093**Garinger (Plaza) Mecklenburg**0.0890.0900.0980.1050.1000.0990.0960.0990.1030.0860.0850.0880.091**Enochville Rowan**0.0860.0880.0920.0990.1020.0940.1030.1080.087**0.080**0.0880.089**Rockwell Rowan**0.0920.0920.1000.0890.1010.1070.0920.0970.1060.098**0.080**0.0860.085**Monroe Union**0.0960.085**0.081**0.100**0.083 0.074** **0.082 0.080** **York York County, SC**0.0850.087**0.079 0.080** 0.0870.092**0.076 0.080** 0.096**0.076 0.071** **0.079 0.078** NOTES:**Values displayed in bold represent exceedances of the 8-hour ozone National Ambient Air Quality Stand** **ards. Underlined values represent 4th highest values from** **Plaza monitoring site. The Plaza monitor was moved to the Garinger site lo** **cation in 2000. Shaded areas reflect that no monitoring data was av** **ailable. 2** II. Historic 8-Hour Ozone Design Values (ppm) forthe Charlotte-Gastonia-Rock Hill, NC-SC Nonattainment Area**The fourth highest 8-hour ozone averages listed in Table C-1 were used to calculate the design values** **shown in Table C-2. Design values were calculated from the 1994-1996 design value per** **iod through the 2004-2006 design value periods for each monitor in the Charlotte-Gastonia** **Rock Hill Nonattainment area. Design values were c alculated by looking at three years of ozone data.** **This is completed by averaging the fourth highest 8-hour ozone concentration for each of the** **three years of concern. Once this three-year avera ge is completed, all the values after the third** **decimal place are truncated. The ozone concentrati on is then rounded and compared with the 8-hour ozo** **ne standard, which is 0.08 ppm. For instance, York’s design value for 2003-2005 is the** **average of 0.076 ppm, 0.071 ppm, and 0.079 ppm (see Table 1). The average of these three** **ozone concentrations is 0.075333 ppm. After trunca ting the figures after the third decimal place, the** **design values is 0.075 ppm (see Table 2). When compared to the standard, this design value for** **the York monitor is rounded to 0.08 ppm, which is not above the 0.08 ppm standard for that** **particular design value period.**Table C-2:Historic 8-Hour Ozone Design Values (ppm) for Charlotte-Gastonia-Rock Hill, NC-SC Nonattainment Area**Monitoring Sites** **County 1994-** **1996 1995-** **1997 1996-** **1998 1997-** **1999 1998-** **2000 1999-** **2001 2000-** **2002 2001-** **2003 2002-** **2004 2003-** **2005 2004-** **2006 Crouse Lincoln 0.087 0.086 0.086 0.087 0.090 0.091** **0.094 0.092 0.086 0.081 0.079 Arrowood Mecklenburg 0.094 0.096 0.099 0.100 0.098** **0.092 0.089 0.084 0.081 0.078 0.080 County Line Mecklenburg 0.093 0.097 0.103 0.104 0.1** **04 0.101 0.102 0.098 0.092 0.087 0.088 Garinger** **(Plaza) Mecklenburg 0.092 0.097 0.101 0.101 0.098 0.098 0.0** **99 0.096 0.091 0.086 0.088 Enochville Rowan** **0.088 0.093 0.097 0.098 0.099 0.101 0.099 0.091 0. 085 0.085** **Rockwell Rowan 0.094 0.093 0.096 0.099 0.100 0.098 0.098 0.100 0.094 0.088 0.083** **Monroe Union 0.087 0.088 0.088 0.085 0.079 0.078** **York York County,** **SC 0.083 0.082 0.082 0.086 0.085 0.082 0.084 0.084 0.0** **81 0.075 0.076**NOTES:**Values displayed in bold represent violations of t he 8-hour ozone National Ambient Air Quality Standa** **rds. Underlined values represent design values that use** **fourth highest values from the Plaza monitoring sit e.** **Shaded areas reflect that data was not available to calculate design value.**