Appendix C 

Historic Air Quality Data 

 
TABLE OF CONTENTS 

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

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

 Table C-1: Historic Fourth Highest 8-Hour Ozone Values (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 (ppm) for the Charlotte-Gastonia-Rock Hill, NCSC Nonattainment Area.....................2 
1 

HISTORIC AIR QUALITY DATA

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

 8-hour running averages were calculated for each year (1994-2006) at each monitor in the Charlotte-Gastonia-Rock HThis was done by calculating 8-hour running averages from hourly data at each site in the area. After calculating the 8-hoeach hour of the day, the maximum 8-hour ozone concentrations were selected for each day at each site. Sorting by date 

the rankings of the maximum 8-hour ozone concentrations for each day of the year. The fourth highest 8-hour concenteach data set for each monitor. These concentrations are listed for each year at each monitor in Table 1. 

Table C-1: 

Historic Fourth Highest 8-Hour Ozone Values (ppm) for Charlotte-Gastonia-Rock Hill, NC-SC Nonattai

Monitoring Sites County 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 

Crouse Lincoln 0.088 0.090 0.084 0.085 0.090 0.087 0.094 0.094 0.095 0.089 Arrowood Mecklenburg 0.087 0.096 0.099 0.094 0.104 0.104 0.087 0.086 0.094 0.073 County Line Mecklenburg 0.091 0.091 0.099 0.101 0.110 0.103 0.101 0.099 0.107 0.088 Garinger (Plaza) Mecklenburg 0.089 0.090 0.098 0.105 0.100 0.099 0.096 0.099 0.103 0.086 Enochville Rowan 0.086 0.088 0.092 0.099 0.102 0.094 0.103 0.108 0.087 Rockwell Rowan 0.092 0.092 0.100 0.089 0.101 0.107 0.092 0.097 0.106 0.098 Monroe Union 0.096 0.085 0.081 0.100 0.083 York York County, SC 0.085 0.087 0.079 0.080 0.087 0.092 0.076 0.080 0.096 0.076 

NOTES: Values displayed in bold represent exceedances of the 8-hour ozone National Ambient Air Quality Standards. 

Underlined values represent 4th highest values from Plaza monitoring site. The Plaza monitor was moved to the Garinger site location in 2000. Shaded areas reflect that no monitoring data was available. 
2 

II. Historic 8-Hour Ozone Design Values (ppm) for the 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 Ta

were calculated from the 1994-1996 design value period through the 2004-2006 design value periods for each monitor in Rock Hill Nonattainment area. Design values were calculated by looking at three years of ozone data. This is completed 

highest 8-hour ozone concentration for each of the three years of concern. Once this three-year average is completed, all decimal place are truncated. The ozone concentration is then rounded and compared with the 8-hour ozone standard, winstance, York’s design value for 2003-2005 is the average of 0.076 ppm, 0.071 ppm, and 0.079 ppm (see Table 1). Thozone concentrations is 0.075333 ppm. After truncating the figures after the third decimal place, the design values is 0

When compared to the standard, this design value for the York monitor is rounded to 0.08 ppm, which is not above the 0.0

particular design value period. 

Table C-2: 

Historic 8-Hour Ozone Design Values (ppm) for Charlotte-Gastonia-Rock Hill, NC-SC Nonattainme

Monitoring 

Sites County 1994- 1996 1995- 1997 1996- 1998 1997- 1999 1998- 2000 1999- 2001 2000- 2002 2001- 2003 200

200

Crouse Lincoln 0.087 0.086 0.086 0.087 0.090 0.091 0.094 0.092 0.086 Arrowood Mecklenburg 0.094 0.096 0.099 0.100 0.098 0.092 0.089 0.084 0.08County Line Mecklenburg 0.093 0.097 0.103 0.104 0.104 0.101 0.102 0.098 0.092 Garinger (Plaza) Mecklenburg 0.092 0.097 0.101 0.101 0.098 0.098 0.099 0.096 0.09Enochville Rowan 0.088 0.093 0.097 0.098 0.099 0.101 0.099 0.09Rockwell Rowan 0.094 0.093 0.096 0.099 0.100 0.098 0.098 0.100 0.094 Monroe Union 0.087 0.088 0.088 0.085 York York County, SC 0.083 0.082 0.082 0.086 0.085 0.082 0.084 0.084 0.08NOTES: Values displayed in bold represent violations of the 8-hour ozone National Ambient Air Quality Standards. 

Underlined values represent design values that use fourth highest values from the Plaza monitoring site. Shaded areas reflect that data was not available to calculate design value.