Clean Air Act Section 110(l) NonInterference Demonstration to Support the 

Gasoline Reid Vapor Pressure (RVP) 

Standard Relaxation in Gaston and 

Mecklenburg Counties

for

The Charlotte-Gastonia-Salisbury, NC 

2008 8-Hour Ozone Maintenance Area

Prepared by

North Carolina Department of Environment and Natural Resources

Division of Air Quality

April 16, 2015
(This page intentionally left blank)
Non-Interference Demonstration to Support i

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table of Contents

1.0 OVERVIEW ............................................................................................................................ 1

2.0 REQUEST FOR A UNIFORM REID VAPOR PRESSURE STANDARD IN THE 

CHARLOTTE OZONE MAINTENANCE/MARGINAL NONATTAINMENT AREA ............. 2

2.1 CURRENT EPA-APPROVED MAINTENANCE PLAN ................................................... 3

3.0 NON-INTERFERENCE DEMONSTRATION....................................................................... 4

3.1 EMISSIONS INVENTORIES.............................................................................................. 4

3.2 OZONE SENSITIVITY IN NORTH CAROLINA ............................................................ 16

3.3 NON-INTERFERENCE WITH OZONE NAAQS ............................................................ 16

3.4 NON-INTERFERENCE WITH THE NAAQS FOR CARBON MONOXIDE,

PARTICULATE MATTER, SULFUR DIOXIDE, AND NITROGEN DIOXIDE .................. 18

4.0 CONCLUSIONS.................................................................................................................... 20

5.0 REVISED SECTIONS........................................................................................................... 21

List of Tables

Table 3.1 Point Source NOx Emissions (tons/day) ....................................................................... 6

Table 3.2 Point Source VOC Emissions (tons/day)....................................................................... 7

Table 3.3 Area Source NOx Emissions (tons/day)........................................................................ 8

Table 3.4 Area Source VOC Emissions (tons/day) ....................................................................... 9

Table 3.5 On-road Mobile Source NOx Emissions (tons/day).................................................... 10

Table 3.6 On-road Mobile Source VOC Emissions (tons/day) ................................................... 11

Table 3.7 Nonroad Mobile Source NOx Emissions (tons/day) ................................................... 12

Table 3.8 Nonroad Mobile Source VOC Emissions (tons/day)................................................... 13

Table 3.9 Total Anthropogenic NOx Emissions (tons/day)......................................................... 14

Table 3.10 Total Anthropogenic VOC Emissions (tons/day)...................................................... 15

Table 3.11 Maintenance Demonstration for North Carolina Portion of the 

Charlotte Nonattainment Area ...................................................................................................... 17

Table 3.12 Safety Margin for North Carolina Portion of the Charlotte Nonattainment Area ..... 17
Non-Interference Demonstration to Support 1

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

1.0 OVERVIEW

In addition to requesting the Charlotte marginal nonattainment area be redesignated as attaining 

the 2008 8-hour ozone National Ambient Air Quality Standard (NAAQS), the North Carolina 

Division of Air Quality (DAQ) is requesting a relaxation of the federal summertime Reid vapor 

pressure (RVP) gasoline standard for Mecklenburg and Gaston Counties from 7.8 to 9.0 pounds 

per square inch (psi). The lower RVP requirement is effective in these two counties from June 1 

through September 15 each year. This request is a stand-alone analysis separate from the 

“Redesignation Demonstration and Maintenance Plan for the Charlotte-Gastonia-Salisbury, 

North Carolina 2008 8-Hour Ozone Marginal Nonattainment Area” State Implementation Plan 

(SIP). 

The DAQ has examined both the man-made and natural sources of volatile organic compound 

(VOC) emissions and their contribution to ozone formation in North Carolina. Because of the 

generally warm and moist climate of North Carolina, vegetation abounds in many forms, and 

forested lands naturally cover much of the state. As a result, the biogenic sector is the most 

abundant source of VOCs in North Carolina and accounts for approximately 90% of the total 

VOC emissions statewide. The overwhelming abundance of biogenic VOCs makes the majority 

of North Carolina a nitrogen oxide (NOx) limited environment for the formation of ozone. Since 

reductions in man-made VOC emissions do not reduce ozone levels, having a lower RVP 

standard during the summer months is not an effective control measure for ozone. In addition, it 

results in higher fuel costs, which places additional costs on businesses and consumers.

Our analysis conducted to support the non-interference demonstration under Section 110(l) of the 

Clean Air Act (CAA) indicates that increasing the RVP from 7.8 to 9.0 psi in Gaston and 

Mecklenburg Counties would not negatively impact the redesignation demonstration and 

maintenance plan for the Charlotte area. The emissions inventory comparison between the 7.8 

and 9.0 psi RVP standards indicates that the estimated future year emissions are slightly higher 

for NOx and VOC. By 2026, relaxing the RVP standard is estimated to increase emissions by

only 0.01 ton/day of NOx and 0.32 ton/day of VOC from all man-made emissions sources. This 

is equivalent to a 0.01% and 0.32% increase in total man-made emissions of NOx and VOC, 

respectively. When biogenic VOC emissions from natural sources (average of 183.90 tons/day 

from April through October using the EPA’s 2011 National Emissions Inventory) are added to 

the man-made emissions (100.46 tons/day), the actual VOC emissions increase is only 0.11% 

(0.32/284.36 tons/day x 100). 
Non-Interference Demonstration to Support 2

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Despite this small increase, the safety margin for the Charlotte maintenance area remains 

relatively unchanged. From 2014 through 2026, under the current RVP standard of 7.8 psi, 

summer day NOx emissions decrease by 62.64 tons/day and VOC emissions decrease by 12.66

tons/day which demonstrates that relaxing the RVP standard in Gaston and Mecklenburg 

Counties will not interfere with maintaining the overall downward trend in the emissions for the 

Charlotte area. The DAQ believes these small increases are within the uncertainty of the 

emissions inventory modeling analyses. 

The DAQ concludes that relaxation of the federal RVP standard would not interfere with the 

attainment and maintenance of the NAAQS. The DAQ has developed a contingency plan based 

on a number of triggers and tracking mechanisms that will ensure that the Charlotte 

nonattainment area continues to maintain compliance with the 2008 8-hour ozone NAAQS. In 

addition, based on the DAQ’s review of emissions and ambient monitoring data, it is very 

unlikely that relaxing the RVP standard in Gaston and Mecklenburg Counties will result in a 

violation of the NAAQS for carbon monoxide (CO), sulfur dioxide (SO2), nitrogen dioxide 

(NO2), and particulate matter with an aerodynamic diameter less than 2.5 micrometers (PM2.5). 

Therefore, with this submission, the DAQ believes the requirements of the CAA Section 110(1) 

have been met. 

2.0 REQUEST FOR A UNIFORM REID VAPOR PRESSURE STANDARD IN THE

CHARLOTTE OZONE MAINTENANCE/MARGINAL NONATTAINMENT AREA

The RVP is a federal control measure intended to lower air emissions of VOCs, a precursor to 

ozone formation. In the mid-to-late 1990s, the discovery that a significant amount of VOC 

emissions comes from natural sources began to change the understanding of the atmospheric 

chemistry, particularly in the Southeastern United States. Statewide, natural sources account for 

90% of total VOC emissions. Today, we know that controlling ozone throughout North Carolina 

and much of the Southeast is more effectively done through emissions reductions of NOx. With 

this scientific understanding in mind, the DAQ is requesting the relaxation of the 7.8 psi RVP 

requirement in Gaston and Mecklenburg Counties. 

This analysis shows that North Carolina can implement the 9.0 psi gasoline standard without 

interfering with the attainment of the NAAQS. The DAQ’s analysis indicates that increasing the 

RVP from 7.8 to 9.0 psi would not negatively impact the redesignation request and maintenance

plan. Therefore, the DAQ requests that the U.S. Environmental Protection Agency (EPA) relax 

the 7.8 psi RVP requirement and specify 9.0 psi as the applicable gasoline volatility standard for 

the entire maintenance area year round. This action would provide significant economic relief to 
Non-Interference Demonstration to Support 3

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

North Carolina consumers and businesses because it will (1) provide for a uniform gasoline 

standard throughout North Carolina, (2) lower summertime (June 1 – Sept. 15) gasoline prices at 

the pump for consumers and (3) simplify the gasoline distribution process for fuel distributors

while not impacting the state’s ability to maintain the 2008 ozone standard or any of the other 

NAAQs. 

2.1 CURRENT EPA-APPROVED MAINTENANCE PLAN

Section 110(a)(1) of the CAA requires that each state adopt and submit to the EPA a plan which

provides for implementation, maintenance and enforcement of primary and secondary standards 

for all areas within the state. The EPA stated that a 110(a)(1) maintenance plan is required for 

those areas that are designated as attainment/unclassifiable for the 2008 8-hour ozone standard 

and are designated as attainment for the 1997 8-hour and 1979 1-hour ozone standards with an 

approved maintenance plan. The three fundamental building blocks to this plan are: 

 A foundation control program that contains all of the necessary federal and state control 

measures to maintain the 2008 8-hour ozone standard. 

 A maintenance demonstration which shows the projected decreases in ozone-precursor 

emissions from all sectors (e.g., point, area, on-road and nonroad) from the effective start 

through the last year of the plan (i.e., 2014 through 2026). The demonstration shows that 

NOx and VOC emissions are expected to decrease substantially during this time: NOx 

emissions are expected to decrease by 62.64 tons/day and VOC emissions are expected to 

decrease by 12.66 tons/day from 2014 through 2026.

 A contingency plan which details actions that will be taken should the design value of 

any monitor within the maintenance area violate the 2008 8-hour standard.

The EPA-approved maintenance plan for the Charlotte marginal nonattainment area will be the 

document to which the proposed relaxation of the gasoline RVP standard will be made. The

proposed and related revisions to the maintenance plan are described herein. 
Non-Interference Demonstration to Support 4

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

3.0 NON-INTERFERENCE DEMONSTRATION

3.1 EMISSIONS INVENTORIES

The 110(a)(1) maintenance plan requires the development of an attainment inventory and a 

future year inventory for VOC and NOx emissions for those areas that must maintain the 2008 8-

hour ozone NAAQS. The Charlotte 8-hour ozone maintenance area; consisting all of 

Mecklenburg County and a part of Gaston, Cabarrus, Lincoln, Rowan, Union and Iredell 

Counties; meets the 110(a)(1) maintenance plan conditions as follows: 

 The attainment inventory year must be one of the three years on which the 8-hour ozone 

attainment designation was based. The base year of 2014 was chosen since it is a year 

that falls within the attaining design value period of 2012-2014. 

 The future inventory year is at least 10 years after the date that the EPA approves the 

redesignation request and maintenance plan. For this reason, 2026 was selected as the 

last year of the future inventory year is 2026. 

 Finally, to be consistent with the EPA guidance, emissions inventories were prepared for 

the interim years of 2015, 2018 and 2022 that demonstrate a consistent, downward trend 

in emissions. 

The emissions inventories are comprised of four major types of sources: point, area, on-road and 

nonroad. The projected emissions inventories have been estimated using projected rates of 

growth in population, traffic, economic activity, and other parameters. Naturally occurring, or 

biogenic, emissions are not included in the emissions inventory comparison, as these emissions 

are outside the state’s span of control. 

Relaxation of the RVP standard for Gaston and Mecklenburg Counties results in a slight increase 

in NOx and VOC emissions for on-road sources, and a slight increase in VOC emissions for 

nonroad and area sources. The remainder of this section provides a summary of the results. 

Appendix B to the redesignation request and maintenance plan SIP provides a detailed 

discussion on how the base and future year emission inventories were developed for each source 

category. For the applicable source categories, Appendix B presents emissions for Gaston and 

Mecklenburg Counties for the current summertime RVP standard of 7.8 psi and emissions for a 

9.0 psi standard. 
Non-Interference Demonstration to Support 5

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

For point sources, Table 3.1 and Table 3.2 provide a summary of NOx and VOC emissions with 

the current 7.8 psi and proposed 9.0 psi gasoline standard, respectively. The table also shows a 

comparison of emissions associated with the two standards in terms of net absolute difference 

and percent change. No changes to point source emissions occur due to the relaxation of the 

RVP standard because the gasoline standard would not affect the air pollution sources reported in

the point source inventory. 

For area sources, relaxation of the RVP standard only affects VOC emissions associated with the 

gasoline service station unloading - stage I controls source category. A summary of the area 

source NOx and VOC emissions is presented in Table 3.3 and Table 3.4, respectively. Total area 

source VOC emissions are estimated to increase by 0.04 to 0.05 ton/day depending on the year. 

A summary of the on-road mobile source NOx and VOC emissions is presented in Table 3.5 and 

Table 3.6, respectively. The MOVES2014 model estimates a NOx increase of 0.11 ton/day and 

VOC increase of 0.18 ton/day in year 2015 due to RVP relaxation. For 2026, MOVES2014 

model estimates a NOx increase of 0.01 ton/day and VOC increase of 0.04 ton/day due to RVP 

relaxation. The net change in emissions associated with the RVP relaxation decline from 2015 

through 2026 because of the benefits of the RVP standard on cleaner vehicle fleets is less than 

those for older fleets. Note that the DAQ is uncertain of the technical reason behind the modelpredicted NOx emissions increases associated with relaxing the RVP standard for a given year. 

A discussion of the dependency between NOx emissions changes and gasoline RVP was not 

found in the model documentation, and a specific correlation equation could not be identified. 

For detailed discussion on how the on-road mobile emission inventory was developed, see 

Appendix B.3. 

A summary of the nonroad mobile source NOx and VOC emissions is presented in Table 3.7 and 

Table 3.8, respectively. The relaxation of the RVP standard only affects VOC emissions from 

nonroad mobile sources as shown in the Table 3.8. The EPA’s nonroad model estimates a VOC 

increase of 0.20 ton/day in 2015 and 0.24 ton/day in 2026 due to RVP relaxation. The nonroad 

model estimates no increase in NOx emissions from 2015 through 2026. 

The sum totals of the man-made emissions for the North Carolina portion of the Charlotte 

nonattainment area are tabulated in Table 3.9 and Table 3.10. Overall, total NOx emissions are 

estimated to increase by 0.11 ton/day in 2015 and 0.01 ton/day in 2026. For VOC, total 

emissions are estimated to increase by 0.42 ton/day in 2015 and 0.32 ton/day in 2026 due to RVP 

relaxation. As explained later in Sections 3.2 through 3.4 of this analysis, these increases are not 

expected to impact ozone levels in the Charlotte area. 
Non-Interference Demonstration to Support 6

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.1 Point Source NOx Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 1.72 1.80 1.94 2.07 2.20

Gaston1, 2 16.50 17.25 10.72 16.16 5.29

Iredell1 2.02 2.03 2.04 2.04 2.05

Lincoln1 0.18 0.84 0.95 1.20 0.73

Mecklenburg2 8.56 8.77 9.46 10.45 12.00

Rowan1 2.80 3.16 3.51 3.71 3.76

Union1 0.59 0.62 0.66 0.70 0.72

Total 32.38 34.47 29.28 36.33 26.75

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 1.80 1.94 2.07 2.20

Gaston1, 2 17.25 10.72 16.16 5.29

Iredell1 2.03 2.04 2.04 2.05

Lincoln1 0.84 0.95 1.20 0.73

Mecklenburg2 8.77 9.46 10.45 12.00

Rowan1 3.16 3.51 3.71 3.76

Union1 0.62 0.66 0.70 0.72

Total 34.47 29.28 36.33 26.75

Net Change in ton/day emissions 0.00 0.00 0.00 0.00

% Change in ton/day emissions 0.00% 0.00% 0.00% 0.00%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline. 
Non-Interference Demonstration to Support 7

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.2 Point Source VOC Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 0.99 1.03 1.15 1.17 1.24

Gaston1, 2 1.82 1.90 2.06 2.16 2.22

Iredell1 0.68 0.68 0.69 0.69 0.69

Lincoln1 1.50 1.54 1.72 1.83 1.94

Mecklenburg2 3.36 3.45 3.73 4.02 4.36

Rowan1 2.30 2.40 2.70 2.85 3.14

Union1 1.38 1.42 1.57 1.64 1.74

Total 12.03 12.42 13.62 14.36 15.33

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 1.03 1.15 1.17 1.24

Gaston1, 2 1.90 2.06 2.16 2.22

Iredell1 0.68 0.69 0.69 0.69

Lincoln1 1.54 1.72 1.83 1.94

Mecklenburg2 3.45 3.73 4.02 4.36

Rowan1 2.40 2.70 2.85 3.14

Union1 1.42 1.57 1.64 1.74

Total 12.42 13.62 14.36 15.33

Net Change in ton/day emissions 0.00 0.00 0.00 0.00

% Change in ton/day emissions 0.00% 0.00% 0.00% 0.00%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline. 
Non-Interference Demonstration to Support 8

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.3 Area Source NOx Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 0.97 0.96 0.96 0.96 0.96

Gaston1, 2 1.30 1.28 1.28 1.29 1.29

Iredell1 0.54 0.53 0.54 0.56 0.55

Lincoln1 0.40 0.40 0.40 0.40 0.40

Mecklenburg2 6.07 6.01 6.01 6.01 6.00

Rowan1 0.87 0.86 0.85 0.85 0.85

Union1 1.25 1.24 1.24 1.24 1.23

Total 11.40 11.28 11.28 11.31 11.28

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 0.96 0.96 0.96 0.96

Gaston1, 2 1.28 1.28 1.29 1.29

Iredell1 0.53 0.54 0.56 0.55

Lincoln1 0.40 0.40 0.40 0.40

Mecklenburg2 6.01 6.01 6.01 6.00

Rowan1 0.86 0.85 0.85 0.85

Union1 1.24 1.24 1.24 1.23

Total 11.28 11.28 11.31 11.28

Net Change in ton/day emissions 0.00 0.00 0.00 0.00

% Change in ton/day emissions 0.00% 0.00% 0.00% 0.00%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline. 
Non-Interference Demonstration to Support 9

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.4 Area Source VOC Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 5.09 5.13 5.26 5.42 5.59

Gaston1, 2 5.24 5.30 5.42 5.59 5.75

Iredell1 3.08 3.13 3.26 3.43 3.58

Lincoln1 2.56 2.57 2.64 2.74 2.82

Mecklenburg2 20.59 20.73 21.15 21.70 22.22

Rowan1 5.23 5.28 5.40 5.56 5.72

Union1 6.09 6.12 6.26 6.43 6.60

Total 47.88 48.26 49.39 50.87 52.28

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 5.13 5.26 5.42 5.59

Gaston1, 2 5.30 5.43 5.60 5.75

Iredell1 3.13 3.26 3.43 3.58

Lincoln1 2.57 2.64 2.74 2.82

Mecklenburg2 20.77 21.19 21.73 22.26

Rowan1 5.28 5.40 5.56 5.72

Union1 6.12 6.26 6.43 6.60

Total 48.30 49.44 50.91 52.32

Net Change in ton/day emissions 0.04 0.05 0.04 0.04

% Change in ton/day emissions 0.08% 0.10% 0.08% 0.08%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline. 
Non-Interference Demonstration to Support 10

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.5 On-road Mobile Source NOx Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 6.60 5.93 3.94 2.79 1.86

Gaston1, 2 8.11 7.23 4.60 3.04 1.97

Iredell1 3.36 3.05 2.05 1.41 0.93

Lincoln1 3.00 2.75 1.84 1.23 0.76

Mecklenburg2 26.99 24.12 14.35 9.63 6.85

Rowan1 6.42 5.75 3.73 2.56 1.59

Union1 5.67 5.14 3.41 2.28 1.51

Total 60.15 53.97 33.92 22.94 15.47

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 5.93 3.94 2.79 1.86

Gaston1, 2 7.26 4.62 3.04 1.98

Iredell1 3.05 2.05 1.41 0.93

Lincoln1 2.75 1.84 1.23 0.76

Mecklenburg2 24.20 14.39 9.65 6.85

Rowan1 5.75 3.73 2.56 1.59

Union1 5.14 3.41 2.28 1.51

Total 54.08 33.98 22.96 15.48

Net Change in ton/day emissions 0.11 0.06 0.02 0.01

% Change in ton/day emissions 0.20% 0.18% 0.09% 0.06%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline. 
Non-Interference Demonstration to Support 11

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.6 On-road Mobile Source VOC Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 4.15 3.89 3.01 2.53 2.04

Gaston1, 2 4.61 4.24 3.05 2.31 1.72

Iredell1 1.95 1.82 1.40 1.10 0.82

Lincoln1 1.91 1.81 1.37 1.07 0.79

Mecklenburg2 14.40 13.28 10.00 8.18 6.64

Rowan1 3.76 3.48 2.57 1.93 1.41

Union1 3.54 3.30 2.54 2.04 1.56

Total 34.32 31.82 23.94 19.16 14.98

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 3.89 3.01 2.53 2.04

Gaston1, 2 4.29 3.08 2.32 1.73

Iredell1 1.82 1.40 1.10 0.82

Lincoln1 1.81 1.37 1.07 0.79

Mecklenburg2 13.41 10.09 8.22 6.67

Rowan1 3.48 2.57 1.93 1.41

Union1 3.30 2.54 2.04 1.56

Total 32.00 24.06 19.21 15.02

Net Change in ton/day emissions 0.18 0.12 0.05 0.04

% Change in ton/day emissions 0.57% 0.50% 0.26% 0.27%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline.
Non-Interference Demonstration to Support 12

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.7 Nonroad Mobile Source NOx Emissions (tons/day)

Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 2.20 2.04 1.65 1.34 1.16

Gaston1, 2 1.98 1.83 1.49 1.23 1.08

Iredell1 0.94 0.88 0.72 0.58 0.51

Lincoln1 0.78 0.72 0.59 0.49 0.42

Mecklenburg2 15.09 13.99 11.36 9.20 8.11

Rowan1 1.65 1.53 1.26 1.04 0.89

Union1 3.62 3.36 2.72 2.19 1.86

Total 26.26 24.35 19.79 16.07 14.03

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 2.04 1.65 1.34 1.16

Gaston1, 2 1.83 1.49 1.23 1.08

Iredell1 0.88 0.72 0.58 0.51

Lincoln1 0.72 0.59 0.49 0.42

Mecklenburg2 13.99 11.36 9.20 8.11

Rowan1 1.53 1.26 1.04 0.89

Union1 3.36 2.72 2.19 1.86

Total 24.35 19.79 16.07 14.03

Net Change in ton/day emissions 0.00 0.00 0.00 0.00

% Change in ton/day emissions 0.00% 0.00% 0.00% 0.00%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline.
Non-Interference Demonstration to Support 13

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.8 Nonroad Mobile Source VOC Emissions (tons/day)

Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 1.27 1.22 1.17 1.19 1.24

Gaston1, 2 1.29 1.23 1.12 1.10 1.12

Iredell1 0.62 0.59 0.52 0.49 0.49

Lincoln1 0.58 0.55 0.48 0.46 0.46

Mecklenburg2 11.75 11.35 10.82 10.91 11.30

Rowan1 1.30 1.22 1.05 0.96 0.94

Union1 2.08 2.01 1.92 1.93 2.00

Total 18.89 18.17 17.08 17.04 17.55

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 1.22 1.17 1.19 1.24

Gaston1, 2 1.25 1.14 1.12 1.15

Iredell1 0.59 0.52 0.49 0.49

Lincoln1 0.55 0.48 0.46 0.46

Mecklenburg2 11.53 11.01 11.11 11.51

Rowan1 1.22 1.05 0.96 0.94

Union1 2.01 1.92 1.93 2.00

Total 18.37 17.29 17.26 17.79

Net Change in ton/day emissions 0.20 0.21 0.22 0.24

% Change in ton/day emissions 1.10% 1.23% 1.29% 1.37%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline.
Non-Interference Demonstration to Support 14

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.9 Total Anthropogenic NOx Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 11.49 10.73 8.49 7.16 6.18

Gaston1, 2 27.89 27.59 18.09 21.72 9.63

Iredell1 6.86 6.49 5.35 4.59 4.04

Lincoln1 4.37 4.71 3.78 3.32 2.32

Mecklenburg2 56.71 52.89 41.18 35.29 32.96

Rowan1 11.74 11.30 9.35 8.16 7.09

Union1 11.13 10.36 8.03 6.41 5.32

Total 130.19 124.07 94.27 86.65 67.54

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 10.73 8.49 7.16 6.18

Gaston1, 2 27.62 18.11 21.72 9.64

Iredell1 6.49 5.35 4.59 4.04

Lincoln1 4.71 3.78 3.32 2.31

Mecklenburg2 52.97 41.22 35.31 32.96

Rowan1 11.30 9.35 8.16 7.09

Union1 10.36 8.03 6.41 5.32

Total 124.18 94.33 86.67 67.54

Net Change in ton/day emissions 0.11 0.06 0.02 0.01

% Change in ton/day emissions 0.09% 0.06% 0.02% 0.01%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline.
Non-Interference Demonstration to Support 15

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Table 3.10 Total Anthropogenic VOC Emissions (tons/day)

County Current 7.8 psi RVP

2014 2015 2018 2022 2026

Cabarrus1 11.50 11.27 10.59 10.31 10.11

Gaston1, 2 12.96 12.67 11.65 11.16 10.81

Iredell1 6.33 6.22 5.87 5.71 5.58

Lincoln1 6.55 6.47 6.21 6.10 6.01

Mecklenburg2 50.10 48.81 45.70 44.81 44.52

Rowan1 12.59 12.38 11.72 11.30 11.21

Union1 13.09 12.85 12.29 12.04 11.90

Total 113.12 110.67 104.03 101.43 100.14

Proposed 9.0 psi RVP

2015 2018 2022 2026

Cabarrus1 11.27 10.59 10.31 10.11

Gaston1, 2 12.74 11.71 11.20 10.85

Iredell1 6.22 5.87 5.71 5.58

Lincoln1 6.47 6.21 6.10 6.01

Mecklenburg2 49.16 46.02 45.08 44.80

Rowan1 12.38 11.72 11.30 11.21

Union1 12.85 12.29 12.04 11.90

Total 111.09 104.41 101.74 100.46

Net Change in ton/day emissions 0.42 0.38 0.31 0.32

% Change in ton/day emissions 0.38% 0.37% 0.31% 0.32%

1 Emissions for portion of county included in nonattainment area.

2 7.8 psi RVP requirement applies to Mecklenburg and Gaston Counties only. Proposed RVP 

relaxation only affects these two counties. The reaming counties already allow 9.0 psi gasoline.
Non-Interference Demonstration to Support 16

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

3.2 OZONE SENSITIVITY IN NORTH CAROLINA 

A study published in the Journal of Environmental Management concluded that the sensitivity of 

ozone to anthropogenic VOC emissions in the Southeastern United States is 2-3 orders of 

magnitude smaller than the sensitivity of ozone to NOx emissions, primarily due to the 

abundance of biogenic VOC emissions in this region.1 As a result, controlling anthropogenic 

VOC emissions in the Southeast is far less effective than controlling NOx emissions for purposes 

of reducing ozone levels. In fact, the study evaluates the change in ozone concentrations 

resulting from decreases in anthropogenic VOC emissions and indicates that the change in ozone 

concentrations resulting from a 30% decrease in anthropogenic VOC emissions is virtually zero 

in most cases. The virtual non-impact to ozone concentrations due to a change in anthropogenic 

VOC emissions in the Southeast supports the DAQ’s conclusion that VOC emissions changes 

occurring in Gaston and Mecklenburg Counties due to RVP relaxation will not interfere with the 

Charlotte maintenance area’s ability to maintain compliance with the 2008 8-hour ozone 

NAAQS. 

The RVP relaxation results in the highest increase in VOC emissions in year 2026 (0.32 ton/day 

or 0.32% of total man-made emissions). When biogenic VOC emissions from natural sources 

(average of 183.9 tons/day from April through October using the EPA’s 2011 National 

Emissions Inventory) are added to the man-made emissions (100.46 tons/day), the actual VOC 

emissions increase is only 0.11% (0.32/284.36 tons/day x 100). For the reasons cited above, the 

DAQ does not believe that the very small changes to VOC emissions will translate into 

measurable ground-level ozone concentrations changes in the Charlotte area. Consequently, 

maintenance of the 2008 8-hour ozone NAAQS is expected to be preserved. 

3.3 NON-INTERFERENCE WITH OZONE NAAQS

There are currently six ozone monitors located throughout the Charlotte marginal nonattainment 

area and one monitor located in York County, South Carolina, just outside of the nonattainment 

area. The latest design value for the nonattainment area is 0.073 parts per million (ppm) based 

on the data from 2012-2014, and, therefore, is in attainment of the 2008 8-hour ozone NAAQS 

and the nonattainment area is eligible to be considered for redesignation to attainment.

 

1 Odman, M Talat et al., Quantifying the sources of ozone, fine particulate matter, and regional haze in the 

Southeastern United States, 90 Journal of Environmental Management 3155-3168 (2009). 
Non-Interference Demonstration to Support 17

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

In addition, the emissions inventory comparison between the 7.8 and 9.0 psi RVP standards 

indicates that the estimated future year emissions are slightly higher for NOx and VOC 

emissions. The highest NOx increase occurs in the first year the standard is relaxed at 0.11 

ton/day which is equivalent to a 0.09% increase in total man-made emissions. By 2026, relaxing 

the RVP results in an emissions increase of only 0.01 ton/day of NOx or 0.01% increase in total 

man-made NOx emissions. Despite this small increase in NOx emissions, which is the primary 

ozone precursor, the Charlotte area continues to demonstrate a downward trend in NOx and 

VOC emissions through all future years. A large safety margin remains between 2014 and 2026 

to ensure that the area continues to attain the 2008 8-hour ozone NAAQS. Table 3.11 shows the 

difference between the base year emissions and the final year emissions with the proposed RVP 

relaxation request. Table 3.12 shows the corresponding safety margins with the proposed RVP 

standard. 

Table 3.11 Maintenance Demonstration for North Carolina Portion of the 

Charlotte Nonattainment Area

Year NOx (tons/day) VOC (tons/day)

2014 130.18 113.12

2015 124.18 111.09

2018 94.33 104.41

2022 86.67 101.74

2026 67.54 100.46

Difference from

2014 to 2026 -62.64 -12.66

Table 3.12 Safety Margin for North Carolina Portion of the Charlotte Nonattainment Area

Year NOx (tons/day) VOC (tons/day)

2014 N/A N/A

2015 -6.00 -2.03

2018 -35.85 -8.71

2022 -43.51 -11.38

2026 -62.64 -12.66
Non-Interference Demonstration to Support 18

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

The data show that future years’ total man-made emissions continue to follow a declining trend 

with the proposed RVP standard. The 2014 to 2015 safety margin for NOx contains the largest 

impact before and after the RFP relaxation: -6.11 tons/day of NOx with 7.8 psi compared to -

6.00 tons/day of NOx with 9.0 psi. Based on emissions and air quality modeling studies 

conducted on previous RVP relaxation requests, the DAQ does not believe that the resulting 

difference of 0.11 tons/day of NOx (0.09% of total man-made emissions) will have a 

measureable impact on ground-level ozone formation. Subsequently, maintenance of the 2008 8-

hour ozone NAAQS is expected to continue with the proposed 9.0 psi RVP standard. The 

conclusion is further supported by reviewing the safety margin in the final maintenance year. By 

2026, the safety margin with the 7.8 psi RVP is 62.65 tons/day of NOx and 62.64 tons/day of 

NOx with 9.0 psi RVP. The 0.01 ton/day change in the safety margin in year 2026 is expected to 

have no impact on ground-level ozone concentrations. In summary, there is no expectation or 

concern that the small change in emissions due to the relaxation of the RVP standard will affect 

the attainment and maintenance stats of the Charlotte area for the ozone NAAQS. 

3.4 NON-INTERFERENCE WITH THE NAAQS FOR CARBON MONOXIDE, 

PARTICULATE MATTER, SULFUR DIOXIDE, AND NITROGEN DIOXIDE

The current ambient air quality levels for CO are less than 20% of the CO standards. One of the 

two current NAAQS established by EPA for CO is an 8-hour standard of 9 ppm, measured using 

the annual second-highest maximum 8-hour concentration for two consecutive years as the 

design value. The other standard is a 1-hour average of 35 ppm, using the second-highest 1-hour 

average within a given year. Ambient monitoring data for the Charlotte area in the years 2012 

and 2013 show an 8-hour design value of 1.2 ppm, or about 13% of the CO NAAQS. 

Additionally, years 2012 and 2013 ambient monitoring data show maximum 1-hour values of 2.3 

and 1.7 ppm, respectively, within the Charlotte region. Both of these values are well below the 

35 ppm standard set forth in the CO NAAQS. On-road mobile emissions are known to be a large 

component of overall CO emissions. However, for the Charlotte maintenance area, relaxation of 

the RVP standard is estimated to increase CO emissions by approximately 2.78 tons/day or 

0.71% of total on-road mobile source CO emissions in 2015. For 2026, CO emissions are 

estimated to increase by approximately 1.44 tons/day or 0.60% of total on-road mobile source 

CO emissions due to relaxation of the RVP standard. This projected increase in CO emissions is 

comparatively minimal and it is expected that the effect on ambient concentrations of CO will be 

correspondingly minimal as well. Therefore, there is no expectation or concern that this change 

in CO emissions due to the relaxation of the RVP standard will affect the attainment status of the 

Charlotte area CO NAAQS. Nonroad and area sources are not large contributors to CO 

emissions.
Non-Interference Demonstration to Support 19

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

The EPA revised the NO2 standard on February 9, 2010 to establish a new 1-hour standard at a 

level of 100 parts per billion (ppb), based on the 3-year average of the 98th percentile of the 

yearly distribution of 1-hour daily maximum concentrations, to supplement the existing annual 

standard of 53 ppb based on the annual mean concentration. The annual mean NO2

concentration in the Charlotte area was 8 ppb in 2013 or 15% of the annual NO2 NAAQS. For 

the 1-hour standard, the monitoring requirements are focused on near-road monitoring; therefore, 

one focus of this standard is on-road mobile sources. To date, two near-road NO2 monitors have 

been established in North Carolina, one in the Triangle area in January 2014 and the other in the 

Charlotte area in June 2014. The maximum 1-hour NO2 concentration measured at the Triangle 

area near road site in 2014 was 41.2 ppb in March 2014. The maximum 1-hour NO2

concentration measured in the Charlotte area was 43.6 ppb recorded on November 12, 2014. 

Since sufficient data has not yet been collected to determine if North Carolina is violating or 

close to exceeding this 1-hour standard, it is difficult to unequivocally determine whether 

relaxing the RVP standard will result in a violation of the NO2 standard. However, on-road 

mobile sources are a large contributor of NOx emissions and NO2 is a component of NOx. 

MOVES mobile emissions modeling results show that relaxing the RVP standard results in only 

slight increases in NOx emissions for the region (0.20% in 2015 and 0.05% in 2026). Based 

upon these estimates, it can be assumed that the RVP relaxation would likewise only slightly 

increase NO2 emissions and therefore would not greatly affect attainment of the 1-hour NO2

standard. 

On-road, nonroad and area sources are not believed to be large contributors to directly emitted 

PM2.5 or indirectly formed PM2.5 concentrations. In North Carolina, directly emitted PM2.5 is a 

very small component of the overall PM2.5 ambient concentrations. The primary species 

impacting PM2.5 concentrations are the secondarily formed sulfates and organic carbons. In 2013 

the Charlotte area PM2.5 design values were 9.8 micrograms per cubic meter for the annual 

standard or 82% of the annual PM2.5 NAAQS and 22 microgram per cubic meter for the 24-hour 

standard or 63% of the daily PM2.5 NAAQS. MOVES modeling results indicate that the RVP 

relaxation would lead to slight reductions of direct PM2.5 emissions (0.23% in 2015 and 0.61% in 

2026) and would have no effect on SO2 and ammonia emissions. Based on this, it is concluded 

that the RVP relaxation will not affect the attainment of the PM2.5 standard.

Sulfates are formed through the chemical reaction of SO2 and ammonia and the majority of the 

organic carbons come from natural sources like trees. A 2009 analysis of SO2 emissions, which 

is a primary contributor to the formation of PM2.5 within North Carolina, found about 3.3% of 

total SO2 emissions came from on-road, nonroad and area sources combined, while the 

remaining 96.7% came from point sources (see “Redesignation Demonstration and Maintenance 
Non-Interference Demonstration to Support 20

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

Plan for the Hickory (Catawba County) and Greensboro/Winston-Salem/High Point (Davidson 

and Guilford Counties) Fine Particulate Matter Nonattainment Areas”, submitted to the EPA on 

December 18, 2009, Figure 4-2, p. 4-4). The SO2 design value in 2013 for the Charlotte area 

was 10 ppb or 13% of the hourly SO2 NAAQS.

For the reasons outlined above, it is unlikely that relaxing the RVP standard in Gaston and 

Mecklenburg Counties will result in a violation of the CO, SO2, NO2, and PM2.5 NAAQS. 

4.0 CONCLUSIONS

The most recent three years of ozone monitoring data for the Charlotte maintenance area 

demonstrate compliance with the 2008 8-hour ozone NAAQS. None of the six ozone monitors 

in the area show any violations of the 2008 8-hour ozone NAAQS. Since the 1990’s, there have 

been many major programs enacted in North Carolina that have led to significant actual, 

enforceable emissions reductions which have led to air quality improvements in the Charlotte 

area. The closing (Riverbend) or conversion (Buck) of coal-fired power plants in the Charlotte 

nonattainment area from 2011 through 2013 has also helped to improve air quality in the 

Charlotte maintenance area. In addition, the decline in utilization of the Allen power plant in 

Gaston County has also contributed to air quality improvements in the Charlotte maintenance 

area. The capacity factor for the Allen plant dropped from 30% to 14% from 2011 to 2013, and 

is expected to continue to decline during the forecast period for the maintenance plan. 

The maintenance plan demonstrates that the projected emissions inventory for 2026 is less than 

the base year emissions inventory when the RVP requirement of 7.8 psi is relaxed to 9.0 psi. 

The lower RVP requirement was implemented as a control measure to reduce VOC emissions. 

Since VOC emissions from biogenic sources dominate in the Southeast, controlling ozone in 

North Carolina is most effectively done through reduction in NOx emissions. The noninterference demonstration shows that the slight increase in NOx emissions from 2014 through 

2026 would not affect the declining trends in emissions, and is not expected to result in 

measurable ozone impacts. The safety margin for NOx remains relatively unchanged with the 

9.0 psi RVP standard, and, therefore, will not interfere with maintenance of the ozone NAAQS. 

The relaxation of the RVP standard is also not expected to interfere with the maintenance of the 

other NAAQS. 
Non-Interference Demonstration to Support 21

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

5.0 REVISED SECTIONS OF REDESIGNATION REQUEST AND MAINTENANCE 

PLAN

Following is the complete Pre-hearing Draft of the Redesignation Request and Maintenance Plan 

for the Charlotte-Gastonia-Salisbury, NC 8-hour Ozone Maintenance Area that has been revised 

to reflect changes to NOx and VOC emissions should the EPA approve both the redesignation 

request and maintenance plan as well as the DAQ’s request to relax the RVP standard from 7.8 

psi to 9.0 psi in Gaston and Mecklenburg Counties. The following identifies the sections of the 

redesignation request and maintenance plan that have been revised. For the area, onroad, and 

nonroad source categories for which emissions change due to relaxation of the RVP standard 

from 7.8 to 9.0 psi, Appendix B.2, Appendix B.3 and Appendix B.4 present emissions for both 

the current and proposed RVP standards, respectively.

 Executive Summary

o Conclusion and Request for Redesignation, page v

 Section 3.4 Emissions Inventories and Maintenance Demonstration

o Section 3.4.2 Emission Inventories

 Table 3.5 Area Source VOC Emissions (tons/day), page 35

 Table 3.6 On-road Mobile Source NOx Emissions (tons/day), page 36

 Table 3.7 On-road Mobile Source VOC Emissions (tons/day), page 36

 Table 3.9 Nonroad Mobile Source VOC Emissions (tons/day), page 37

o Section 3.4.3 Summary of Emissions

 Table 3.10 Total Man-Made NOx Emissions for the North Carolina Portion of 

the Charlotte Nonattainment Area (tons/day), page 37

 Table 3.11 Total Man-Made VOC Emissions for the North Carolina Portion of 

the Charlotte Nonattainment Area (tons/day), page 37

o Section 3.4.4 Maintenance Demonstration

 Table 3.12 Maintenance Demonstration for North Carolina Portion of the 

Charlotte Nonattainment Area, page 38

 Table 3.13 Safety Margin for North Carolina Portion of the Charlotte 

Nonattainment Area, page 38

 Section 4.3 MOTOR VEHICLE EMISSION BUDGETS

o Table 4.2 Highway Mobile Source NOx and VOC Emissions in 2014 and 2026 for 

North Carolina Portion of the Charlotte Nonattainment Area, page 44

o Table 4.4 Gaston-Cleveland-Lincoln Metropolitan Planning Organization 

(GCLMPO) MVEB in 2014 and 2026 (kg/day), page 47
Non-Interference Demonstration to Support 22

Gasoline Reid Vapor Pressure Standard April 16, 2015

Relaxation in Gaston and Mecklenburg Counties

o Table 4.5 Charlotte Regional Transportation Planning Organization (CRTPO) -

Rocky River Rural Planning Organization (RRRPO) MVEB in 2014 and 2026 

(kg/day), page 47

o Table 4.6 New Safety Margins for the North Carolina Portion of the Charlotte 

Nonattainment Area (tons/day), page 47

 Section 7.0 Conclusions, page 52
Redesignation Demonstration

And Maintenance Plan

and

Clean Air Act Section 110(l) Non-Interference 

Demonstration to Support the Gasoline Reid 

Vapor Pressure (RVP) Standard Relaxation in 

Gaston and Mecklenburg Counties

for

The Charlotte-Gastonia-Salisbury, North 

Carolina 2008 8-Hour Ozone Marginal 

Nonattainment Area

Prepared by

North Carolina Department of Environment and Natural Resources

Division of Air Quality

April 16, 2015
(This page intentionally left blank)
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal i

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Preface: This document contains the technical support for North Carolina’s Division of Air 

Quality to request the Charlotte-Gastonia-Salisbury 2008 8-hour ozone nonattainment area be 

redesignated as attainment for the 2008 8-hour ozone national ambient air quality standard 

pursuant to §§107(d)(3)(D) and (E) of the Clean Air Act, as amended.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal ii

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

EXECUTIVE SUMMARY

Introduction

Ozone is formed by a complex set of chemical reactions involving volatile organic compounds 

(VOCs), nitrogen oxides (NOx) and to a lesser extent carbon monoxide (CO). These gases are 

generated by utilities, combustion processes, certain industrial processes and even by natural 

sources such as trees. Tailpipe emissions from mobile sources (vehicles) are also significant 

sources of these pollutants. Emissions from smaller sources such as boat engines, lawn mowers 

and construction equipment also contribute to the formation of ozone. Ozone formation is 

promoted by strong sunlight, warm temperatures and light winds and is hence a problem 

predominantly during the hot summer months.

The 2008 8-hour ozone National Ambient Air Quality Standard (NAAQS) is 0.075 parts per 

million (ppm). An exceedance of the 2008 8-hour ozone NAAQS occurs when a monitor 

measures ozone above 0.075 ppm on average for an 8-hour period. A violation of this NAAQS 

occurs when the average of the annual fourth highest daily maximum 8-hour ozone values over 

three consecutive years is greater than or equal to 0.076 ppm. This three-year average is termed 

the “design value” for the monitor. The design value for a nonattainment area is the highest 

monitor design value in the area.

Charlotte-Gastonia-Salisbury Nonattainment Designation

The area surrounding Charlotte-Gastonia-Salisbury, North Carolina, called the Charlotte 

nonattainment area, was designated as marginal nonattainment for the 2008 8-hour ozone 

NAAQS on May 21, 2012 (77 Federal Register (FR) 30088). The nonattainment designation was 

an action taken by the U. S. Environmental Protection Agency (EPA) under Section 107(d) of the 

Clean Air Act (CAA). The CAA requires that some area be designated as nonattainment if a 

monitor is found to be in violation of a NAAQS. For the 2008 8-hour ozone NAAQS, the EPA 

took designation action in 2012 based on 2009-2011 design values. At that time, the design value 

for the Charlotte area was 0.079 ppm.

The Charlotte nonattainment area includes the entire county of Mecklenburg and parts of 

Cabarrus, Gaston, Iredell, Lincoln, Rowan and Union Counties (see Figure 1). The partial 

counties include the townships listed in Table 1. Note that the EPA also designated the portion of 

York County, South Carolina that is adjacent to the Charlotte nonattainment area for the 2008 8-

hour ozone NAAQS. The South Carolina Department of Health & Environmental Control 

(SCDHEC) has developed a redesignation request and maintenance plan for the South Carolina 

portion of the Charlotte nonattainment area which is available upon request.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal iii

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Charlotte Nonattainment Area Boundary

Table 1 Counties and Townships within the Charlotte Nonattainment Area

Cabarrus County Townships

Central Cabarrus Concord* Georgeville Harrisburg Kannapolis Midland

Mount Pleasant Odell Poplar Tent New Gilead Rimertown

Gaston County Townships

Dallas Crowders Mountain Gastonia Riverbend South Point

Iredell County Townships

Coddle Creek Davidson

Lincoln County Townships

Catawba Springs Lincolnton Ironton

Mecklenburg County – All Townships

Rowan County Townships

Atwell China Grove Franklin Gold Hill* Litaker Locke

Providence Salisbury Steele Unity

Union County Townships

Goose Creek Marshville Monroe Sandy Ridge Vance

*Note: Concord Township in Cabarrus County and Gold Hill Township in Rowan County were inadvertently left out 

of North Carolina’s recommendation and EPA’s final designations. In a letter dated January 28, 2014, the DAQ 

requested the EPA to add the missing townships in the state’s 2008 marginal ozone nonattainment area definition. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal iv

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Current Air Quality

There are currently six ozone monitors located throughout the Charlotte nonattainment area and 

one monitor located in York County, South Carolina, just outside of the nonattainment area. The 

latest design value for the nonattainment area is 0.073 ppm based on the data from 2012-2014. 

The 2014 8-hour ozone monitoring data for the Charlotte nonattainment area was fully quality 

assured and officially submitted to the EPA for certification approval on December 12, 2014. The 

EPA concurred with the North Carolina Division of Air Quality (DAQ) and Mecklenburg County 

Air Quality (MCAQ) certification on December 15, 2014. A detailed discussion of air quality 

levels in the region is provided in Section 2.0. 

Maintenance Plan Requirements

The state of North Carolina has implemented permanent and enforceable state and federal actions 

to reduce ozone precursor emissions in the North Carolina portion of the Charlotte nonattainment 

area. In addition, MCAQ has implemented actions to reduce ozone precursor emissions. This 

combination of state, federal, and local actions has resulted in cleaner air in the Charlotte 

nonattainment area, and the anticipated future benefits from these programs are expected to result 

in continued maintenance of the 2008 8-hour ozone NAAQS in this region. State actions include 

the Clean Smokestacks Act; the on-board diagnostic (OBDII) vehicle inspection and maintenance 

(I/M) program that began on July 1, 2002; and voluntary programs to reduce emissions from 

diesel engines. Local actions implemented by MCAQ include a prohibition on open burning and 

a very effective voluntary program called Grants to Replace Aging Diesel Engines (GRADE).

1

 

The GRADE program is designed to reduce NOx emissions by providing businesses and 

organizations funding incentives to replace or repower heavy-duty non-road equipment with 

newer, cleaner, less polluting engines. 

Several federal actions have resulted in lower emissions throughout the eastern portion of the 

country. For on-road and nonroad vehicles, federal actions include the Tier 2 engine standards for 

light- and medium-duty vehicles, heavy-duty engine standards, the low-sulfur gasoline and diesel 

requirements, and off-road engine standards. For stationary sources, federal actions include the 

Mercury and Air Toxics (MATS) rule for electricity generating units (EGUs) and the National 

Emissions Standards for Hazardous Air Pollutants (NESHAP) for industrial, commercial and 

institutional boilers and reciprocating internal combustion engines (RICE). In addition, there are 

several federal actions that will be implemented starting in 2015. These actions will provide for 

additional NOx emissions reductions in and near the Charlotte nonattainment area. For EGUs, 

the future federal actions include compliance with the Cross State Air Pollution Rule (CSAPR)

 

1 http://charmeck.org/mecklenburg/county/LUESA/AirQuality/MobileSources/Pages/GRADE.aspx. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal v

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

and the Tennessee Valley Authority (TVA) consent decree. For on-road vehicles, the future 

federal actions include compliance with the Tier 3 vehicle emissions and fuel standards and 

corporate average fuel economy standards for on-road vehicles. 

Emissions

A base year inventory for NOx and VOC emissions was developed for 2014 since the design 

value for the 2012-2014 period shows attainment of the 2008 8-hour ozone NAAQS. Future year 

emissions inventories were also developed for the interim years 2015, 2018, 2022, and a final

year emission inventory was developed for 2026. For each future year, the total NOx and VOC 

emissions is lower than the 2014 base year emissions. Furthermore, emissions modeling and air 

quality modeling for 2018 and 2030 performed by the EPA for the new Tier 3 engine and fuel 

standards and modeling performed by the Southeastern states for 2018 indicate that the area will 

be in attainment of the 2008 ozone NAAQS.2, 3 The emission inventory comparison demonstrates 

that the Charlotte area is expected to maintain the 2008 8-hour ozone NAAQS through 2026 since 

in no future year are the emissions expected to be greater than they were in the base year. The 

area is also in compliance with Section 110 and Part D requirements of the CAA. 

Conclusion and Request for Redesignation 

Based on the information provided in this State Implementation Plan (SIP) and criteria established 

in Section 107(d)(3)(E) of the CAA, North Carolina is requesting that the EPA redesignate the 

Charlotte-Gastonia-Salisbury nonattainment area to attainment. North Carolina is also requesting 

that the EPA relax the 7.8 pounds per square inch (psi) Reid vapor pressure (RVP) requirement 

for Gaston and Mecklenburg Counties and specify 9.0 psi as the applicable gasoline volatility 

standard for the entire maintenance area year round. The monitoring data clearly show that the 

region has attained the 2008 8-hour ozone standard, and the maintenance demonstration shows 

that the future emission inventories are expected to be lower than the attainment year inventory 

through the implementation of the various federal and state control measures. The CAA Section 

110(l) non-interference demonstration analysis indicates that increasing the RVP from 7.8 to 9.0 

psi in Gaston and Mecklenburg Counties would not negatively impact the redesignation 

demonstration and maintenance plan for the Charlotte area. 

 

2 US EPA, http://www.epa.gov/otaq/documents/tier3/454r14002.pdf. 

3 Southeastern States Air Resource Managers (SESARM); Southeastern Modeling, Analysis and Planning (SEMAP) 

study, http://semap.ce.gatech.edu/sites/default/files/files/projections/base2018b-O3-DVFs-DDVFs-for-4configs.xls.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal vi

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................ ii

1.0 INTRODUCTION .................................................................................................................... 1

1.1 WHAT IS TROPOSPHERIC OZONE? .............................................................................. 1

1.2 CLEAN AIR ACT OF 1990 ................................................................................................ 2

1.3 AIR QUALITY HISTORY ................................................................................................. 2

1.4 CLEAN AIR ACT REDESIGNATION CRITERIA........................................................... 4

2.0 AIR QUALITY......................................................................................................................... 5

2.1 HISTORIC AIR QUALITY (2003 – 2011)......................................................................... 5

2.2 RECENT AIR QUALITY VALUES (2012 –2014)............................................................ 7

2.3 PERMANENT AND ENFORCEABLE EMISSIONS REDUCTIONS ............................. 9

2.4 ADDITIONAL PROGRAMS SUPPORTING MAINTENANCE.................................... 13

2.5 EFFECT NOX CONTROL PROGRAMS ON OZONE LEVELS ................................... 14

3.0 MAINTENANCE PLAN........................................................................................................ 18

3.1 CONCEPT OF NORTH CAROLINA'S MAINTENANCE PLAN.................................. 18

3.2 FOUNDATION CONTROL PROGRAM......................................................................... 19

3.2.1 Federal Control Measures........................................................................................... 19

3.2.2 State Control Measures................................................................................................ 26

3.3 ADDITIONAL PROGRAMS SUPPORTING MAINTENANCE.................................... 28

3.3.1 State Programs Supporting Maintenance.................................................................... 28

3.3.2 Local Programs Supporting Maintenance................................................................... 29

3.4 EMISSIONS INVENTORIES AND MAINTENANCE DEMONSTRATION ............... 30

3.4.1 Theory of Approach.................................................................................................... 30

3.4.2 Emission Inventories................................................................................................... 31

3.4.3 Summary of Emissions............................................................................................... 37

3.4.4 Maintenance Demonstration ....................................................................................... 38

3.4.5 National and Regional Air Quality Assessments in Future Years.............................. 39

3.5 CONTINGENCY PLAN ................................................................................................... 40

3.5.1 Overview..................................................................................................................... 40

3.5.2 Contingency Plan Triggers ......................................................................................... 40

3.5.3 Action Resulting From Trigger Activation................................................................. 41

3.5.4 Tracking Program for Ongoing Maintenance ............................................................. 42

4.0 MOTOR VEHICLE EMISSIONS BUDGET FOR CONFORMITY .................................... 43

4.1 TRANSPORTATION CONFORMITY ............................................................................ 43

4.2 SAFETY MARGIN ........................................................................................................... 43

4.3 MOTOR VEHICLE EMISSION BUDGETS.................................................................... 44

5.0 STATE IMPLEMENTATION PLAN APPROVAL.............................................................. 48

5.1 INTRODUCTION ............................................................................................................. 48
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal vii

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

5.2 EVIDENCE OF COMPLIANCE ...................................................................................... 48

6.0 STATE COMPLIANCE WITH CLEAN AIR ACT REQUIREMENTS............................... 51

7.0 CONCLUSION....................................................................................................................... 52

LIST OF FIGURES

Figure 1.1 Charlotte Nonattainment Area Boundary.......................................................................3

Figure 2.1 Ozone Monitor Locations in the Charlotte Nonattainment Area ...................................5

Figure 2.2 Relationship between high temperature days and number of exceedance days in the 

Charlotte area ..................................................................................................................................17

Figure 2.3 Relationship between high temperature days and maximum 4th highest ozone value in 

the Charlotte Area ...........................................................................................................................17

LIST OF TABLES

Table 1.1 Counties and Townships within the Charlotte Nonattainment Area ...............................3

Table 2.1 Charlotte Area’s Historic 4th Highest 8-hour Ozone Values (2003-2014) ......................6

Table 2.2 Charlotte Area’s Historic Design Values (2003 - 2014)..................................................7

Table 2.3 Charlotte Area’s Current Air Quality Data (2012 -2014)................................................8

Table 2.4 NOx Emissions from NC Sources in EPA’s Air Markets Program Database...............15

Table 2.5 April 1 through September 30 NOx Emissions for Electric Utilities Near Charlotte 

Area (tons/period)...........................................................................................................................16

Table 3.1 Population Percentages Used to Allocate Partial County Emissions ............................31

Table 3.2 Point Source NOx Emissions (tons/day) .......................................................................34

Table 3.3 Point Source VOC Emissions (tons/day).......................................................................34

Table 3.4 Area Source NOx Emissions (tons/day)........................................................................35

Table 3.5 Area Source VOC Emissions (tons/day) .......................................................................35

Table 3.6 On-road Mobile Source NOx Emissions (tons/day)......................................................36

Table 3.7 On-road Mobile Source VOC Emissions (tons/day) .....................................................36

Table 3.8 Nonroad Mobile Source NOx Emissions (tons/day) .....................................................36

Table 3.9 Nonroad Mobile Source VOC Emissions (tons/day).....................................................37

Table 3.10 Total Man-Made NOx Emissions for the North Carolina Portion of the Charlotte 

Nonattainment Area (tons/day).......................................................................................................37

Table 3.11 Total Man-Made VOC Emissions for the North Carolina Portion of the Charlotte 

Nonattainment Area (tons/day).......................................................................................................37

Table 3.12 Maintenance Demonstration for North Carolina Portion of the 

Charlotte Nonattainment Area ........................................................................................................38
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal viii

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 3.13 Safety Margin for North Carolina Portion of the Charlotte Nonattainment Area .......38

Table 3.14 Eight-hour Design Values from SEMAP Photochemical Modeling ...........................39

Table 3.15 Eight-hour Design Values Scenarios from EPA Tier 3 Photochemical Modeling......39

Table 4.1 Percent Increase to Mobile Vehicle Emissions Budget .................................................44

Table 4.2 Highway Mobile Source NOx and VOC Emissions in 2014 and 2026 for North 

Carolina Portion of the Charlotte Nonattainment Area ..................................................................44

Table 4.3 Cabarrus Rowan Metropolitan Planning Organization (CRMPO) MVEB in 2014 and 

2026 (kg/day)..................................................................................................................................46

Table 4.4 Gaston-Cleveland-Lincoln Metropolitan Planning Organization (GCLMPO) MVEB in 

2014 and 2026 (kg/day) ..................................................................................................................47

Table 4.5 Charlotte Regional Transportation Planning Organization (CRTPO) -Rocky River 

Rural Planning Organization (RRRPO) MVEB in 2014 and 2026 (kg/day)..................................47

Table 4.6 New Safety Margins for the North Carolina Portion of the Charlotte Nonattainment 

Area (tons/day)................................................................................................................................47

LIST OF APPENDICES

APPENDIX A: CORRESPONDENCE AND GUIDANCE DOCUMENTS

APPENDIX B.1: POINT SOURCE INVENTORY DOCUMENTATION

APPENDIX B.2: AREA SOURCE INVENTORY DOCUMENTATION

APPENDIX B.3: ON-ROAD MOBILE SOURCE INVENTORY DOCUMENTATION

APPENDIX B.4: NONROAD MOBILE SOURCE INVENTORY DOCUMENTATION
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal ix

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

LIST OF ACRONYMS

Acronym Definition

AADVMT Average annual daily vehicle miles traveled

AEO Annual Energy Outlook

AERR Air Emission Reporting Rule

AMPD Air Markets Program Data

APU Auxiliary Power Units

ARRA American Recovery and Reinvestment Act

AvGas Aviation gasoline

BTU British Thermal Unit

CAA Clean Air Act

CAIR Clean Air Interstate Rule

CAMD Clean Air Markets Division

CDOT Charlotte Department of Transportation

CFR Code of Federal Regulations

CMAQ Congestion Mitigation and Air Quality Improvement

CNG Compressed Natural Gas

CO Carbon Monoxide

CO2 Carbon Dioxide

CRMPO Cabarrus Rowan Metropolitan Planning Organization

CRTPO Charlotte Regional Transportation Planning Organization

CSAPR Cross State Air Pollution Rule

DAQ North Carolina Division of Air Quality

DERA Diesel Emissions Reduction Act

DOC Diesel Oxidation Catalyst

DPF Diesel Particulate Filter

EDMS Emissions and Dispersion Modeling System

EF Emission factor

EGU Electricity Generating Units

EIA Energy Information Administration

EIIP Emissions Inventory Improvement Program

EIS Emissions Information System

EMP Emissions Modeling Platform

EPA United States Environmental Protection Agency

ERTAC Eastern Regional Technical Advisory Committee

oF Degrees Fahrenheit

FAA Federal Aviation Administration

FHWA Federal Highway Administration

FIFRA Federal Insecticide, Fungicide and Rodenticide Act

FIP Federal Implementation Plan

FR Federal Register
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal x

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Acronym Definition

FTR Federal Transport Rule

GACT Generally Available Control Technology

GCLMPO Gaston-Cleveland-Lincoln Metropolitan Planning Organization

GHG Greenhouse Gas

GIS Geographic Information System

GRADE Grants to Replace Aging Diesel Engines

GSE Ground Support Equipment

HAP Hazardous Air Pollutant

HC Hydrocarbons

HDDV Heavy duty diesel vehicles

HDGV Heavy duty gas vehicles

HPMS High performance monitoring system

I/M Inspection and Maintenance

ICI Industrial and commercial/institutional

KCLT Charlotte Douglas International Airport

kg/day Kilograms/Day

lbs Pounds

LDDT1 Light duty diesel trucks 1

LDDT1 Light duty diesel trucks 2

LDDV Light duty diesel vehicles

LDGT1 Light duty gas trucks 1

LDGT2 Light duty gas trucks 2

LDGV Light duty gas vehicles

LPG Liquid petroleum gas

LTO Landing and takeoff

MACT Maximum Achievable Control Technology

MATS Mercury Air Toxics rule

MC Motorcycles

MCAQ Mecklenburg County Air Quality

MOA Memorandum of Agreement

MOVES Motor Vehicle Emissions Simulator

mpg miles per gallon

MPO Metropolitan Planning Organization

MRM Metrolina Regional Model

MTP Metropolitan Transportation Plan

MVEB Motor Vehicle Emission Budget

NAAQS National Ambient Air Quality Standard

NAICS North American Industrial Classification System

NCAA North Carolina Air Awareness

NCAC North Carolina Administrative Code
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal xi

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Acronym Definition

NCDAQ North Carolina Division of Air Quality

NCDOT North Carolina Department of Transportation

NCFS North Carolina Forest Service

NCPCM North Carolina Petroleum and Convenience Marketers

NEI National Emissions Inventory

NESHAP National Emissions Standards for Hazardous Air Pollutants

NG Natural Gas

NHTSA National Highway Traffic Safety Administration

NMOG Non-methane Organic Gases

NO2 Nitrogen Dioxide

NOx Nitrogen Oxides

NSPS New Source Performance Standard

OBD Onboard Diagnostic

PAD Petroleum Administration for Defense

PFC Portable fuel container

PM Particulate Matter

PM10 Particulate matter with an aerodynamic diameter less than or equal to 10 

micrometers

PM2.5 Particulate matter with an aerodynamic diameter less than or equal to 2.5 

micrometers

ppb Parts per billion

ppm Parts per million

psi pounds per square inch

QA Quality Assurance

QAPP Quality Assurance Project Plan

RICE Reciprocating Internal Combustion Engines

RPO Rural Planning Organization

RRRPO Rock River Rural Planning Organization

RT Road type

RVP Reid Vapor Pressure

SCDHEC South Carolina Department of Health and Environmental Control

SEMAP Southeastern Modeling, Analysis and Planning

SESARM Southeastern States Air Resource Managers

SIP State Implementation Plan

SO2 Sulfur Dioxide

SUV Sport Utility Vehicle

TAF Terminal Area Forecast

TDM Transportation Demand Model

TIP Transportation Improvement Program

TVA Tennessee Valley Authority

UI Urban interstate
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal xii

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Acronym Definition

UF Urban freeway

USCBP United Sates Census Bureau, County Business Patterns

USDA United States Department of Agriculture

UST Underground storage tank

VHT Vehicle Hours Traveled

VMT Vehicle Miles Traveled

VOC Volatile Organic Compounds
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 1

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

1.0 INTRODUCTION

1.1 WHAT IS TROPOSPHERIC OZONE?

Ozone, a strong chemical oxidant, adversely impacts human health through effects on respiratory 

function and can also damage forests and crops. Ozone is not emitted directly by the electric 

utilities, industrial sources or motor vehicles but instead, is formed in the lower atmosphere, the 

troposphere, by a complex series of chemical reactions involving nitrogen oxides (NOx), 

resulting from the utilities, combustion processes and motor vehicles, and reactive volatile 

organic compounds (VOCs). VOCs include many industrial solvents, toluene, xylene and 

hexane as well as the various hydrocarbons (HC) that are evaporated from the gasoline used by 

motor vehicles or emitted through the tailpipe following combustion. 

Ozone formation is promoted by strong sunlight, warm temperatures, and light winds. High 

concentrations tend to be a problem in the eastern United States only during the hot summer 

months when these conditions frequently occur. Therefore, the U. S. Environmental Protection 

Agency (EPA) mandates seasonal monitoring of ambient ozone concentrations in North Carolina 

from April 1 through October 31 (40 CFR 58 App. D, 2.5).4 The DAQ has examined both the 

man-made and natural sources of VOC emissions and their contribution to ozone formation in 

North Carolina. Because of the generally warm and moist climate of North Carolina, vegetation 

abounds in many forms, and forested lands naturally cover much of the state. As a result, the 

biogenic sector is the most abundant source of VOCs in North Carolina and accounts for 

approximately 90% of the total VOC emissions statewide. The overwhelming abundance of 

biogenic VOCs makes the majority of North Carolina a NOx limited environment for the 

formation of ozone. This is supported by a study published in the Journal of Environmental 

Management that concludes that the sensitivity of ozone to anthropogenic VOC emissions in the 

Southeastern United States is 2-3 orders of magnitude smaller than the sensitivity of ozone to 

NOx emissions, primarily due to the abundance of biogenic VOC emissions in this region.5 As a 

result, controlling anthropogenic VOC emissions in the Southeast is far less effective than 

controlling NOx emissions for purposes of reducing ozone levels.

On March 12, 2008, the EPA revised the primary (health) and secondary (welfare) National 

Ambient Air Quality Standards (NAAQS) for ozone to a level of 0.075 parts per million (ppm). 

An exceedance of the 2008 8-hour ozone NAAQS occurs when a monitor measures ozone above 

0.075 ppm on average for an 8-hour period. A violation of this NAAQS occurs when the 

average of the annual fourth highest daily maximum 8-hour ozone values over three consecutive 

 

4 40 CFR 58 App. D, 2.5.

5 Odman, M Talat et al., Quantifying the sources of ozone, fine particulate matter, and regional haze in the 

Southeastern United States, 90 Journal of Environmental Management 3155-3168 (2009).
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 2

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

years is greater than or equal to 0.076 ppm. This three-year average is termed the “design value” 

for the monitor. The design value for a nonattainment area is the highest monitor’s design value 

in the area. 

1.2 CLEAN AIR ACT OF 1990

Since the 1977 amendments to the Clean Air Act (CAA), areas of the country that had not 

attained the ambient standard for a particular pollutant were formally designated as 

nonattainment for that pollutant. This formal designation concept was retained in the 1990 CAA 

Amendments. 

1.3 AIR QUALITY HISTORY

The area surrounding Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina, called the 

Metrolina area (see Figure 1.1), was designated nonattainment for the 1997 8-hour ozone 

NAAQS on April 30, 2004.6 The 1997 8-hour ozone NAAQS was set at 0.085 ppm. The 

Metrolina nonattainment area includes the North Carolina counties of Cabarrus, Gaston, Lincoln, 

Mecklenburg, Rowan and Union; Coddle Creek and Davidson Townships in Iredell County, 

North Carolina; and the Rock Hill Metropolitan Planning Organization boundary in York County, 

South Carolina. On December 2, 2013, the EPA approved North Carolina’s redesignation 

demonstration and maintenance plan for the 1997 8-hour ozone NAAQS for the CharlotteGastonia-Rock Hill, North Carolina area.7

 

On July 20, 2012, the EPA designated the Charlotte-Gastonia-Salisbury, North Carolina 

nonattainment area (referred to as the Charlotte nonattainment area) as “marginal” nonattainment 

for the 2008 8-hour ozone standard (Figure 1.1) based on the ambient data from 2009-2011. The 

nonattainment area includes all of Mecklenburg County and portions of Cabarrus, Gaston, 

Iredell, Lincoln, Rowan, and Union Counties. Table 1.1 identifies the townships in each county 

that are included in the Charlotte nonattainment area. At that time, the design value for the 

Charlotte area was 0.079 ppm. The official designation and classification was published in the 

Federal Register (FR) on May 21, 2012.8 The designation became effective on July 20, 2012.

 

6 69 FR 23858.

7 78 FR 72036.

8 77 FR 30088.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 3

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Figure 1.1 Charlotte Nonattainment Area Boundary

Table 1.1 Counties and Townships within the Charlotte Nonattainment Area

Cabarrus County Townships

Central Cabarrus Concord* Georgeville Harrisburg Kannapolis Midland

Mount Pleasant Odell Poplar Tent New Gilead Rimertown

Gaston County Townships

Dallas Crowders Mountain Gastonia Riverbend South Point

Iredell County Townships

Coddle Creek Davidson

Lincoln County Townships

Catawba Springs Lincolnton Ironton

Mecklenburg County – All Townships

Rowan County Townships

Atwell China Grove Franklin Gold Hill* Litaker Locke

Providence Salisbury Steele Unity

Union County Townships

Goose Creek Marshville Monroe Sandy Ridge Vance

*Note: Concord Township in Cabarrus County and Gold Hill Township in Rowan County were inadvertently left 

out of North Carolina’s recommendation and EPA’s final designations. In a letter dated January 28, 2014, the North 

Carolina Division of Air Quality (DAQ) requested EPA to add the missing townships in the state’s 2008 marginal 

ozone nonattainment area definition. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 4

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

There are currently six ozone monitors located throughout the Charlotte nonattainment area and 

one monitor located in York County, South Carolina. The North Carolina Division of Air 

Quality (DAQ) operates three of the monitors in the Charlotte area, the Mecklenburg County Air 

Quality (MCAQ) operates three of the monitors in the Mecklenburg County, and South Carolina 

Department of Health and Environmental Control (SCDHEC) operates the York County monitor.

In 2013, all but two monitors, Garinger and County Line located in Mecklenburg County, came 

into attainment of the 2008 8-hour ozone NAAQS. With the completion of the 2014 ozone 

season, the Garinger and County Line monitors attained the standard as well. The 2012-2014

design value for Charlotte nonattainment area is 0.073 ppm. 

1.4 CLEAN AIR ACT REDESIGNATION CRITERIA

Section 107(d)(3)(E) of the CAA, as amended, states an area can be redesignated to attainment if 

the following conditions are met:

1. The EPA has determined that the NAAQS have been attained. For ozone, the areas must 

show that the average of the fourth highest 8-hour ozone values from three (3) complete, 

consecutive calendar years of quality-assured air quality monitoring data must be below 

0.076 ppm.

2. The applicable implementation plan has been fully approved by the EPA under Section 

110(k).

3. The EPA has determined that the improvement in air quality is due to permanent and 

enforceable reductions in emissions. To demonstrate this, the state should estimate the 

percent reduction (from the year used to determine the design value for designation and 

classification) achieved from federal, state, and local measures.

4. The state has met all applicable requirements for the area under Section 110 and Part D.

5. The EPA has fully approved a maintenance plan, including a contingency plan, for the 

areas under Section 175A.

In the following sections, the DAQ provides the technical data necessary to show that the 

Charlotte-Gastonia-Salisbury nonattainment area has attained and is expected to maintain the 

2008 8-hour ozone standard, and has met the requirements for redesignation set forth above. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 5

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

2.0 AIR QUALITY

2.1 HISTORIC AIR QUALITY (2003 – 2011) 

The DAQ and MCAQ have collected ambient monitoring data for the Charlotte area since the 

late seventies. Figure 2.1 shows the location of the six ozone monitors throughout the Charlotte 

nonattainment area. In addition, one additional ozone monitor is located in York County, South 

Carolina (not shown in Figure 2.1). These monitors were installed in accordance with the Code 

of Federal Regulations (CFR) 40 CFR 58. 

Figure 2.1 Ozone Monitor Locations in the Charlotte Nonattainment Area

Tables 2.1 and 2.2 show the air quality data and corresponding design values for the monitors in 

the Charlotte region, respectively, from 2003 to 2014. As shown in Table 2.2, the design values 

for most of the monitors near and downwind of Charlotte have been declining rapidly in the past 

several years. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 6

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 2.1 Charlotte Area’s Historic 4th Highest 8-hour Ozone Values (2003-2014)

Monitor 4

th Highest 8-hour Ozone Values (ppm)

2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Crouse

AIRS ID #37-109-0004

Lincoln County

0.089 0.074 0.082 0.082 0.085 0.079 0.065 0.072 0.077 0.076 0.064 0.064

Garinger

AIRS ID #37-119-0041

Mecklenburg County

0.086 0.085 0.088 0.091 0.093 0.085 0.069 0.082 0.088 0.080 0.067 0.065

Arrowood

AIRS ID #37-119-1005

Mecklenburg County

0.073 0.077 0.085 0.078 0.087 0.073 0.068 0.078 0.082 0.073 0.062 0.063

County Line

AIRS ID #37-119-1009

Mecklenburg County

0.088 0.083 0.090 0.093 0.096 0.093 0.071 0.082 0.083 0.085 0.066 0.068

Rockwell

AIRS ID #37-159-0021

Rowan County

0.098 0.080 0.086 0.085 0.096 0.084 0.071 0.077 0.077 0.080 0.062 0.064

Enochville1

AIRS ID #37-159-0022

Rowan County

0.087 0.080 0.088 0.089 0.095 0.082 0.073 0.078 0.078 0.077 0.063 -----

Monroe

AIRS ID #37-179-0003

Union County

0.083 0.074 0.082 0.080 0.082 0.080 0.067 0.071 0.073 0.075 0.062 0.067

York

AIRS ID #45-091-0006

York County

0.076 0.071 0.079 0.078 0.080 0.075 0.062 0.065 0.065 0.065 0.061 0.056

1 Monitoring data for 2014 are not available for this monitor because it was shut down in 2014. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 7

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 2.2 Charlotte Area’s Historic Design Values (2003 - 2014)

Monitor Design Value (ppm)

03-05 04-06 05-07 06-08 07-09 08-10 09-11 10-12 11-13 12-14

Crouse

AIRS ID #37-109-0004

Lincoln County

0.081 0.079 0.083 0.082 0.076 0.072 0.071 0.075 0.072 0.068

Garinger

AIRS ID #37-119-0041

Mecklenburg County

0.086 0.088 0.090 0.089 0.082 0.078 0.079 0.083 0.078 0.070

Arrowood

AIRS ID #37-119-1005

Mecklenburg County

0.078 0.080 0.083 0.079 0.076 0.073 0.076 0.077 0.072 0.066

County Line

AIRS ID #37-119-1009

Mecklenburg County

0.087 0.088 0.093 0.094 0.086 0.082 0.078 0.083 0.078 0.073

Rockwell

AIRS ID #37-159-0021

Rowan County

0.088 0.083 0.089 0.088 0.083 0.077 0.075 0.078 0.073 0.068

Enochville1

AIRS ID #37-159-0022

Rowan County

0.085 0.085 0.090 0.088 0.083 0.077 0.076 0.077 0.072 ----

Monroe

AIRS ID #37-179-0003

Union County

0.079 0.078 0.081 0.080 0.076 0.072 0.070 0.073 0.070 0.068

York

AIRS ID #45-091-0006

York County

0.075 0.076 0.079 0.077 0.072 0.067 0.064 0.065 0.063 0.060

Note: Bolded values represent violations of the 2008 8-hour ozone standard.

1 2012-2014 design value for this monitor is not available because it was shut down in 2014. 

2.2 RECENT AIR QUALITY VALUES (2012 –2014) 

Under the CAA, a marginal classification for the 2008 8-hour ozone NAAQS requires North 

Carolina to attain the standard within three years of designation, or July 20, 2015. However, in 

the 2008 Ozone Implementation Rule, the EPA extended the compliance date to December 31, 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 8

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

2015.9 In a recent ruling by the U.S. Court of Appeals for the District of Columbia Circuit, the 

extension deadline was vacated, among other decisions.10 

The most recent three years of ozone monitoring data (2012-2014) for the Charlotte

nonattainment area demonstrate compliance with the 2008 8-hour ozone NAAQS. Table 2.3 is a 

summary of the fourth highest 8-hour average ozone concentration and the design value at each 

of the monitors in the Charlotte region for 2012-2014. 

Table 2.3 Charlotte Area’s Current Air Quality Data (2012 -2014)

Monitor Year 4

th Highest 8-hour 

ozone values (ppm)

Design Value (ppm)

2012-2014

Crouse

AIRS ID #37-109-0004

Lincoln County

2012 0.076

2013 0.064 0.068

2014 0.064

Garinger

AIRS ID #37-119-0041

Mecklenburg County

2012 0.080

2013 0.067 0.070

2014 0.065

Arrowood

AIRS ID #37-119-1005

Mecklenburg County

2012 0.073

2013 0.062 0.066

2014 0.063

County Line

AIRS ID #37-119-1009

Mecklenburg County

2012 0.085

2013 0.066 0.073

2014 0.068

Rockwell

AIRS ID #37-159-0021

Rowan County

2012 0.080

2013 0.062 0.068

2014 0.064

Monroe

AIRS ID #37-179-0003

Union County

2012 0.075

2013 0.062 0.068

2014 0.067

York

AIRS ID #45-091-0006

York County

2012 0.065

2013 0.061 0.060

2014 0.055

The 2014 8-hour ozone monitoring data for the Charlotte nonattainment area was fully quality 

assured and officially submitted to the EPA for certification approval on December 12, 2014. 

 

9 78 FR 34178.

10 http://www.cadc.uscourts.gov/internet/opinions.nsf/E97A64FFBFE4DC1D85257DB70054D5EE/$file/12-1321-

1528834.pdf.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 9

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

The EPA concurred with the DAQ and MCAQ certification on December 15, 2014. The 

Enochville site in Rowan County was shut down in 2014, but the most recent design value for 

that site was 0.072 ppm in 2011-2013 and it was not the highest value in Rowan County or the 

greater Charlotte area at the time of its shutdown.

The monitoring data shown above demonstrates that the Charlotte area is attaining the 2008 8-

hour ozone standard, and is on schedule with the compliance date mandated in the CAA and 

upheld by the D.C. Circuit Court. 

2.3 PERMANENT AND ENFORCEABLE EMISSIONS REDUCTIONS

There are several state and federal measures that have been enacted in recent years that have

ensured permanent and enforceable emissions reductions. A list of those measures that 

contributed to the permanent and enforceable emission reductions are summarized here and are 

more fully described in Section 3.2. 

The federal measures that have been implemented include: 

 Tier 2 vehicle and fuel standards: Implementation began in 2004 and requires all 

passenger vehicles in each manufacture’s fleet to meet an average standard of 0.07 

grams of NOx per mile. Additionally, in January 2006 the sulfur content of gasoline 

was required to be on average 30 ppm which assists in lowering NOx emissions. 

Most gasoline sold in North Carolina prior to January 2006 had a sulfur content of 

about 300 ppm. These emission reductions are federally enforceable.

 Tier 3 vehicle and fuel standards: Implementation begins in 2017 with full 

compliance required by 2025. Tier 3 requires all passenger vehicles to meet an 

average standard of 0.03 gram/mile of NOx. Compared to Tier 2, the Tier 3 tailpipe 

standards for light-duty vehicles are expected to reduce NOx and VOC emissions by 

approximately 80%. Tier 3 vehicle standards also include evaporative standards 

using onboard diagnostics (OBD) that will result in a 50% reduction in VOC 

emissions over Tier 2. The rule reduces the sulfur content of gasoline to 10 ppm 

starting in January 2017. These emission reductions will be federally enforceable.

 National program for greenhouse gas (GHG) emissions and fuel economy standards: 

The federal GHG and fuel economy standards apply to light-duty cars and trucks in 

model years 2012-2016 (phase 1) and 2017-2025 (phase 2). The final standards are 

projected to result in an average industry fleet-wide level of 163 grams/mile of carbon 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 10

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

dioxide (CO2) which is equivalent to 54.5 miles per gallon (mpg) if achieved 

exclusively through fuel economy improvements. The fuel economy standards will 

result in less fuel being consumed, and therefore less NOx emissions released. These 

emission reductions will be federally enforceable.

 Heavy-duty gasoline and diesel highway vehicle standards: Implementation of the 

program began in 2004 with full implementation in 2010. The program was 

estimated to reduce NOx emissions by 95% and required that the sulfur content of 

fuel be reduced to 15 ppm. These emission reductions are federally enforceable.

 Medium- and heavy-duty vehicle fuel consumption and GHG standards: Began 

implementation in 2014 and requires on-road vehicles to achieve from a 7% to 20% 

reduction in CO2 emissions and fuel consumption by 2018. The decrease in fuel 

consumption will result in a 7% to 20% decrease in NOx emissions. These emission 

reductions will be federally enforceable.

 Large nonroad diesel engine standards: Phased in between 2008 through 2014, the 

combined engine and fuel requirements are expected to reduce NOx emissions by 

90% and reduce the sulfur content in the nonroad diesel fuel to 15 ppm. These 

emission reductions are federally enforceable.

 Nonroad spark-ignition engine and recreational engine standards: Tier 1 of these 

standards was implemented in 2004 and Tier 2 started in 2007. These standards 

reduce NOx emissions by 80%. These emission reductions are federally enforceable.

 Clean Air Interstate Rule (CAIR) and Cross State Air Pollution Rule (CSAPR): In 

May 2005, the EPA promulgated CAIR to reduce NOx and SO2 emissions from 

electricity generating units (EGUs). After court challenges to CAIR, the EPA issued 

CSAPR in July 2011. CSAPR will take effect starting January 1, 2015 for SO2 and 

annual NOx, and May 1, 2015 for ozone season NOx. Combined with other final 

state and EPA actions, the CSAPR will reduce power plant SO2 emissions by 73%

and NOx emissions by 54% from 2005 levels. The emission reductions will be 

federally enforceable.

 Tennessee Valley Authority (TVA) Consent Decree: In January 2009, a federal court 

required TVA coal-fired EGUs to install modern pollution controls for SO2 and NOx. 

After an appeals court reversed the decision, North Carolina, TVA, and several other 

parties agreed to a settlement. The settlement caps NOx and SO2 emissions at all of 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 11

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

TVA’s coal-fired facilities to permanent levels of 52,000 tons of NOx in 2018 and 

110,000 tons of SO2 in 2019. These emission reductions are federally enforceable.

 Boiler and Reciprocating Internal Combustion Engine (RICE) National Emissions 

Standards for Hazardous Air Pollutants (NESHAP): The NESHAPs for industrial, 

commercial and institutional boilers and RICE are expected to result in a small 

decrease in VOC emissions. Boilers must comply with the NESHAP by January 31, 

2016 for all states except North Carolina which has a compliance date in May 2019

(see following discussion under state measures). RICE owners and operators had to 

comply with the NESHAP by May 3, 2013. These emission reductions are federally 

enforceable.

 Utility Mercury Air Toxics Standards (MATS) and New Source Performance 

Standards (NSPS): On February 16, 2012, the EPA published final rules for both the 

(1) MATS for new and existing coal- and oil-fired EGUs and (2) NSPS for fossil-fuel 

fired electric utility, industrial-commercial-institutional and small industrialcommercial-institutional steam generating units.11

 The MATS reduce emissions of 

toxic air pollutants from EGUs larger than 25 megawatts that burn coal or oil for the 

purpose of generating electricity for sale and distribution through the national electric 

grid to the public. For the NSPS, the EPA revised the standards that new coal- and 

oil-fired power plants must meet for NOx, SO2, and particulate matter (PM). While 

MATS is still under court review, and portions of it may be overturned, the rule can 

be expected to result in the reduction of both NOx and SO2 emissions in addition to 

the reduction in mercury and other air toxic emissions. The emission reductions 

associated with the MATS and revised NSPS are federally enforceable.

The state measures that have been implemented include:

 Vehicle Emissions Inspection and Maintenance (I/M) Program: In 1999, the North 

Carolina State Legislation passed the Clean Air Bill that expanded the on-road 

vehicle I/M program from 9 to 48 counties. It was phased-in in the Charlotte 

nonattainment area from July 1, 2002 through January 1, 2004. This program reduces 

NOx, VOC and CO emissions. The rule for the I/M program was submitted to the 

EPA for adoption into the State Implementation Plan (SIP) in August 2002 and was 

federally approved in October 2002. Therefore, these emission reductions are both 

state and federally enforceable. 

 

11 77 FR 9304.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 12

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

On February 5, 2015, the EPA approved a change to North Carolina’s I/M rules 

triggered by a state law which exempted plug-in vehicles and the three newest model 

year vehicles with less than 70,000 miles on their odometers from emission 

inspection in all areas in North Carolina where I/M is required.12 In North Carolina’s 

Section 110(l) demonstration, the state showed that the change in the compliance rate 

from 95% to 96% more than compensates for the NOx and VOC emissions increase. 

The EPA-approved change to the I/M rules was effective March 9, 2015, and are state 

and federally enforceable. See Section 3.2.2 of this SIP for a more detailed 

discussion of this change.

 Clean Smokestacks Act: This state law requires coal-fired power plants to reduce 

annual NOx emissions by 77% by 2009, and to reduce annual SO2 emissions by 49%

by 2009 and 73% by 2013. This law set a NOx emissions cap of 56,000 tons/year for 

2009 and SO2 emissions caps of 250,000 tons/year and 130,000 tons/year for 2009 

and 2013, respectively. The public utilities cannot meet these emission caps by 

purchasing emission credits. The EPA approved the statewide emissions caps as part 

of the Charlotte SIP on September 26, 2011. In 2013, the power plants subject to this 

law had combined NOx emissions of 38,857 tons/year, well below the 56,000 

tons/year cap. The emissions cap has been met in all subsequent years as well. These 

emissions limits are enforceable at both the federal and state level.

 Boiler NESHAP: Because of delays associated with the EPA’s promulgation of the 

boiler NESHAP, North Carolina adopted and implemented equivalent emission 

limitations by permit under Section 112(j) of the CAA.13 These limitations apply to 

owners and operators of industrial, commercial and institutional boilers and process 

heaters burning natural gas, coal, oil or biomass beginning in 2013. These emissions

limits are enforceable at both the federal and state level. 

 Transportation Conformity Memorandum of Agreements (MOAs): The Conformity 

MOAs are signed by federal and state transportation agencies and local air quality 

organizations and the MPOs subject to transportation conformity requirements for 

applicable transportation-related NAAQs and satisfies the requirement in the CAA 

Section 176(c). The DAQ chose through rulemaking to develop Conformity MOAs 

to ensure that interagency consultation procedures for transportation conformity are 

followed in each of the nonattainment or maintenance areas in the state.

 

12 Approval and Promulgation of Implementation Plans; North Carolina; Inspection and Maintenance Program 

Updates, 80 FR, 6455.

13 15A NCAC 02D .1109 - 112(j) Case-by-Case Maximum Achievable Control Technology.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 13

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

2.4 ADDITIONAL PROGRAMS SUPPORTING MAINTENANCE

This section provides a brief summary of state and local programs that have been implemented in 

the Charlotte area to maintain compliance with the NAAQS. Although these are important 

programs that help to ensure compliance with the NAAQS, they have not been relied upon as 

federally enforceable measures. These state and local programs are more fully described in 

Section 3.3. 

State programs that have been implemented include:

 Air awareness program: The North Carolina Air Awareness Program is a public 

outreach and education program of the DAQ. The goal of the program is to reduce 

air pollution though voluntary actions by individuals and organizations. The program 

seeks to educate individuals about (1) the sources of air pollution; (2) the health 

effects of air pollution and how these effects can be mitigated by modification of 

outdoor activities on ozone action days; and (3) simple "action tips", such as 

carpooling, vehicle maintenance and energy conservation that reduce individual 

contributions to air pollution. One of the major program components is the daily air 

quality forecast. The DAQ produces the 8-hour ozone forecasts and corresponding 

air quality index for the Charlotte forecast area from April 1 through October 31 of 

each year.14 Additionally, the DAQ produces daily PM forecasts for the Charlotte 

area.

 Grant Program: The DAQ has offered multiple forms of grant funding from state 

and federal funds to help cover the costs associated with emission reduction projects

across the state. These projects include diesel engine replacements, diesel oxidation 

catalyst retrofits, marine diesel repowers, replacing gasoline vehicles with electric 

vehicles, vehicle replacement and many more. Grant projects that have been 

awarded have helped to reduce PM, NOx, CO and VOC emissions from mobile 

sources.

 Open burning rule: This rule prohibits open burning of man-made materials 

throughout the state. Additionally, the rule prohibits open burning of yard waste in 

areas that the DAQ forecasts air quality action days. The open burning regulation 

reduces NOx, VOC, and CO emissions as well as PM with an aerodynamic diameter 

less than or equal to 10 micrometers (PM10) and 2.5 micrometers (PM2.5). 

 

14 See N.C. DAQ http://www.ncair.org/airaware/.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 14

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

 Idle Reduction Regulation: The North Carolina Environmental Management 

Commission adopted the Heavy-Duty Vehicle Idling Restrictions rule to reduce 

unnecessary idling of heavy-duty trucks on July 9, 2009 and the rule became 

effective on July 10, 2010. This rule generally prevents any person who operates a 

heavy-duty vehicle to cause, let, permit, suffer or allow idling for a period of time in 

excess of 5 consecutive minutes in any 60 minute period. This rule is state 

enforceable.

Local program that have been implemented include:

 Open Burning Prohibition: Mecklenburg County prohibits open burning of any kind 

year round, except under extenuating circumstances with an approved burn permit. 

This prohibition is more stringent than the state’s open burning rule and therefore 

enhances this control measure’s overall benefit to the region. The open burning rule 

reduces NOx, VOC, CO, PM10 and PM2.5. These emission reductions are enforceable 

at the local level. 

 GRADE Program: In 2007, MCAQ initiated an air pollution control program called 

GRADE designed to reduce NOx emissions in the Charlotte nonattainment 

area. Funded by federal, state and local county grant money, GRADE provides 

businesses and organizations financial incentives to replace or repower heavy-duty 

non-road equipment with newer, cleaner, less polluting engines. GRADE has funded 

cost effective emission reduction projects operating in multiple segments of the 

economy including construction, landfills, timber logging operations, open pit 

mining, freight transportation, and commercial aviation. As of July 31, 2014, 

GRADE projects have reduced over 350 tons of NOx region-wide. 

 Mobile Source Emissions Reduction Grants: This program reduces NOx, PM, and 

VOC emissions. MCAQ has also received DERA funding as well as American 

Recovery and Reinvestment Act (ARRA) and Congestion Mitigation and Air Quality 

Improvement (CMAQ) program funding. These funds have been used to repower or 

replace existing diesel engines from on-road vehicles and nonroad equipment. Even 

though these emission reductions are voluntary and not enforceable, they are still 

considered permanent reductions. 

2.5 EFFECT NOX CONTROL PROGRAMS ON OZONE LEVELS

The foundation control program for stationary and mobile sources for the Charlotte area has 

significantly reduced NOx emissions enabling the area to demonstrate attainment with the 2008 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 15

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

ozone NAAQS. As an example, historically EGUs have been a significant source of NOx 

emissions contributing to ozone formation during the summer months in the Charlotte area as 

well as statewide. A recent review of the NOx emissions in the EPA’s Air Markets Program 

Data database shows a reduction in over 96,641 tons of NOx from the reporting sources in North 

Carolina between 2002 and 2013. The trend in decreasing NOx emissions from these facilities 

are attributable to a combination of state (Clean Smoke Stacks Act) and federal (CAIR / CSAPR) 

measures and market forces (switching from coal to natural gas due to favorable natural gas 

prices). Table 2.4 presents the annual emissions for the North Carolina sources obtained from 

the EPA’s Air Markets Program Data database. 

Table 2.5 shows trends in NOx emissions from 2002 through 2013 from North Carolina power 

plants in the Charlotte nonattainment area, as well as the power plants located directly north and 

west of the Charlotte region that may impact the nonattainment area. There are four facilities 

located within Gaston, Lincoln and Rowan Counties. The facility west of the Charlotte 

nonattainment area is Cliffside, located in Cleveland County and the facility north of the

Table 2.4 NOx Emissions from NC Sources in EPA’s Air Markets Program Database

Year Annual NOx Emissions from NC 

Sources (tons)

2002 145,706

2003 135,879

2004 124,079

2005 114,300

2006 108,584

2007 64,770

2008 61,669

2009 44,506

2010 57,305

2011 48,889

2012 51,057

2013 49,065

Charlotte nonattainment area is Marshall located in Catawba County. These data are taken from 

the EPA Clean Air Markets Division’s (CAMD) Air Markets Program Data and represent the 

second and third quarters of the year (April through September), the period during which ozone 

levels are the highest. The emissions from these facilities have significantly decreased during 

the ozone season since 2002, with over 12,000 tons of NOx reduction in the 2013 ozone season 

compared to 2002. In addition, two coal-fired power plants (Buck and Riverbend) were retired

in April 2013, which resulted in additional emissions reductions. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 16

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 2.5 April 1 through September 30 NOx Emissions for Electric Utilities Near

Charlotte Area (tons/period)

Facility County 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013

Allen* Gaston 5,011 3,643 4,002 3,589 3,001 3,053 3,082 2,188 2,925 2,738 1,676 1,906

Riverbend* Gaston 2,556 2,703 1,844 1,379 1,417 1,296 1,256 304 1,063 884 109 0

Lincoln* Lincoln 44 20 50 20 52 81 33 6 40 46 10 22

Buck* Rowan 1,084 1,468 1,089 1,286 1,262 870 832 197 783 477 196 61

Marshall Catawba 9,283 9,101 8,243 7,558 6,370 7,253 7,151 4,481 4,861 5,443 5,128 4,777

Cliffside Cleveland 1,944 2,149 1,738 1,782 1,540 1,311 1,173 561 357 469 267 673

Total ----- 19,922 19,084 16,966 15,614 13,642 13,864 13,527 7,737 10,029 10,057 7,386 7,439

*Facility is located within the Charlotte nonattainment area boundary.

Temperature is a key meteorological factor that determines the ozone production potential of a 

given day. In North Carolina, many exceedances occur when the maximum daily temperature is 

90 degrees Fahrenheit (oF) or greater. In recent years, however, foundation control program 

measures have reduced NOx emissions in the Charlotte area to the extent that recent trends are 

showing that ozone levels are lower than the NAAQS even when the daily temperature is 90 oF 

or greater. Figure 2.2 shows the relationship of exceedance days to high temperature days from 

2000 through 2014 for the Charlotte region monitors. The relationship between the maximum 4th

highest ozone value to high temperature days from 2000 through 2014 is displayed in Figure 2.3.

It is important to see how the ozone levels have changed over the last decade in response to 

lower NOx emissions in the state. The worst summer in terms of the number of exceedance days 

and observed 4th highest ozone concentrations was 2002, with 61 exceedance days in the 

Charlotte region and a maximum 4th highest daily average 8-hour concentration of 0.108 ppm. 

That summer there were 49 days when the temperature was 90 oF or greater in the Charlotte 

region. The next highest number of exceedance days occurred in 2007 with 56 days and 74 days 

with temperatures at or above 90 °F, yet the maximum 4th highest daily average 8-hour 

concentration was significantly lower than 2002 at 0.096 ppm. More recently, in the year 2010, 

the Charlotte area experienced the hottest summer of the 21st century with 86 days at or above 90 

°F. However, the Charlotte area only observed 17 exceedance days and the maximum 4th highest 

daily average concentration was only 0.082 ppm. In subsequent years, the 4th-highest values 

have generally decreased as the number of very hot days over 90 degrees has moderated. In 

2014, there were a total of 37 days with a high temperature over 90 degrees, but no exceedances 

of the 2008 8-hour ozone standard and a peak 4th highest daily average value of 0.068 ppm. The 

steady decrease of ozone values over the last 15 years regardless of summertime temperature 

regime illustrates the progress that North Carolina has made and the positive effects of the 

control strategies put in place by North Carolina, Mecklenburg County and the EPA to regulate 

NOx emissions.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 17

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Figure 2.2 Relationship between high temperature days and number of exceedance days in 

the Charlotte area

Figure 2.3 Relationship between high temperature days and maximum 4th highest ozone 

value in the Charlotte Area

0

10

20

30

40

50

60

70

0

10

20

30

40

50

60

70

80

90

100

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

# Exceedance Days

# Days High Temp at least 90F

May-Sept.

#Days T >= 90F #Days O3 >=76PPB

0.06

0.065

0.07

0.075

0.08

0.085

0.09

0.095

0.1

0.105

0.11

0

10

20

30

40

50

60

70

80

90

100

200020012002200320042005200620072008200920102011201220132014

Max 4th-highest value

# Days High Temp at least 90F

May-Sept.

#Days T >= 90F Max. 4th Highest
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 18

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

3.0 MAINTENANCE PLAN

3.1 CONCEPT OF NORTH CAROLINA'S MAINTENANCE PLAN

The state's plan for maintaining compliance with the ambient air quality standard for the 2008

8-hour ozone in the Charlotte-Gastonia-Salisbury nonattainment area consists of three major 

parts: a foundation control program, a maintenance demonstration, and a contingency plan. The 

foundation control program consists of the current federal and state control measures already in 

effect, as well as the future benefits of the federal actions. For EGUs, the future federal actions 

include implementation of the MATS, CSAPR, and carbon rules and the TVA consent decree. 

Additionally, North Carolina will continue to implement and enforce the Clean Smokestacks 

Act. For on-road vehicles, the future federal actions include compliance with the Tier 3 vehicle 

emissions and fuel standards and corporate average fuel economy standards for on-road vehicles. 

Although North Carolina did not rely on the emission reductions from CSAPR or the TVA 

consent decree for maintenance of the 2008 8-hour ozone standard, these actions will result in 

additional reductions in NOx emissions regionally.

The foundation control program includes federally and state enforceable control programs that 

have been adopted and implemented by the DAQ. These programs will remain enforceable and 

ensure that maintenance of the 2008 8-hour ozone standard will continue. Sources are prohibited 

from reducing or removing emission controls (anti-backsliding) following the redesignation of 

the area unless such a change is first approved by the EPA as a revision to the North Carolina 

SIP that is consistent with Section 110(l) of the CAA.

For the maintenance demonstration, the base year of 2014 was chosen since it is a year that falls 

within the attaining design value period of 2012-2014. The interim years 2015, 2018 and 2022

were chosen based on consultation with the EPA. The final year of the maintenance 

demonstration is 2026, since the CAA requires maintenance for at least 10 years after the EPA 

approves the redesignation demonstration and maintenance plan. The maintenance 

demonstration consists of a comparison between the 2014 baseline emissions inventory and the 

projected emissions inventories (for 2015, 2018, 2022, and 2026), which consider economic and 

population growth. The comparison shows that the total emissions in each of the interim years 

and the final year is estimated to be lower than in the base year, which demonstrates maintenance 

of the 2008 8-hour ozone standard. The reductions in emissions are due to the foundation 

control programs outlined below. 

The North Carolina contingency plan involves tracking and triggering mechanisms to determine 

when contingency measures are needed and a process of implementing appropriate control 

measures. The primary trigger of the contingency plan will be a violation of the ambient air 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 19

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

quality standard for 2008 8-hour ozone standard. The secondary trigger will be a monitored air 

quality pattern that suggests an actual 2008 8-hour ozone NAAQS violation may be imminent. 

The SCDHEC has developed a redesignation demonstration and maintenance plan for the South 

Carolina portion of the nonattainment area. Contact the SCDHEC for a copy of the South 

Carolina redesignation demonstration and maintenance plan.

3.2 FOUNDATION CONTROL PROGRAM

The main element of the maintenance plan is the foundation control program. The foundation 

control program consists of a combination of federal and state control measures necessary to 

maintain the ambient air quality standards. The purpose of the foundation control program is to 

prevent the ambient air quality standards from being violated and thereby eliminate the need for 

more costly controls being imposed on industry and the general public. Each component of the 

foundation control program is essential in demonstrating maintenance of the air quality 

standards. The following provides a summary of each federal and state control measure included 

in the foundation control program for the Charlotte nonattainment area. All of these programs 

have already been implemented or are in the process of being implemented.

3.2.1 Federal Control Measures

Tier 2 Vehicle and Fuel Standards

Federal Tier 2 vehicle standards require all passenger vehicles in a manufacturer’s fleet, 

including light-duty trucks and sport utility vehicles (SUVs), to meet an average standard of 0.07 

gram/per mile of NOx. Implementation began in 2004, with full compliance required by 2007. 

The Tier 2 standards also cover passenger vehicles over 8,500 pounds gross vehicle weight 

rating (the larger pickup trucks and SUVs), which are not covered by the Tier 1 regulations. For 

these vehicles, the standards were phased in beginning in 2008, with full compliance required by 

2009. The Tier 2 standards require vehicles to be 77% to 95% cleaner. The Tier 2 rule also 

reduced the sulfur content of gasoline to 30 ppm starting in January of 2006. Most gasoline sold 

in North Carolina prior to January 2006 had a sulfur content of about 300 ppm. Sulfur occurs 

naturally in gasoline and interferes with the operation of catalytic converters on vehicles, which 

results in higher NOx emissions. Lower-sulfur gasoline is necessary to achieve the Tier 2 

vehicle emission standards.

15

 These emission reductions are federally enforceable.

 

15 Fact Sheet, Office of Mobile Sources, EPA-420-F-99-051, December 1999.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 20

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Tier 3 Vehicle and Fuel Standards 

Federal Tier 3 vehicle standards require all passenger vehicles in a manufacturer’s fleet, 

including light-duty trucks and SUVs, to meet an average standard of 0.03 gram/per mile of 

NOx. Heavy-duty passenger vehicles must meet average standards of 0.178 to 0.247 gram/per 

mile of NOx depending on vehicle classification. Implementation begins in 2017, with full 

compliance required by 2025. Compared to current standards in 2014, the Tier 3 tailpipe 

standards for light-duty vehicles are expected to reduce non-methane organic gases (NMOG) and 

NOx by approximately 80%. The Tier 3 program is expected to reduce per-vehicle PM 

standards by approximately 70%. The heavy-duty tailpipe standards represent about a 60% 

reduction in both fleet average NMOG+NOx and per vehicle PM standards. Tier 3 vehicle 

standards also require evaporative standards including OBD that will result in a 50% reduction in 

VOC emissions from Tier 2 for all 2017 and later light-duty and on-road gasoline-powered 

heavy-duty vehicles. The Tier 3 rule also reduced the sulfur content of gasoline to 10 ppm 

starting in January 2017. Tier 2 standards had limited the sulfur content to 30 ppm. Sulfur 

occurs naturally in gasoline and interferes with the operation of catalytic converters on vehicles, 

which results in higher NOx emissions.

16

 These emission reductions are federally enforceable.17

National Program for GHG Emissions and Fuel Economy Standards

The EPA and the National Highway Traffic Safety Administration (NHTSA) jointly developed 

the federal GHG and fuel economy standards for light-duty cars and trucks in model years 2012-

2016 (phase 1) and 2017-2025 (phase 2). The EPA also aligned implementation of the Tier 3 

program with the second phase of the EPA and NHTSA federal GHG and fuel economy 

standards program. Together, phases 1 and 2 of the final standards are projected to result in an 

average industry fleet-wide level of 163 grams/mile of CO2 in model year 2025, which is 

equivalent to 54.5 mpg if achieved exclusively through fuel economy improvements.18 The fuel 

economy standards will result in less fuel being consumed, and therefore less NOx emissions 

released. These emission reductions will be federally enforceable.

Heavy-Duty Gasoline and Diesel Highway Vehicles Standards

The EPA standards designed to reduce NOx and VOC emissions from heavy-duty gasoline and 

diesel highway vehicles began to take effect in 2004. A second phase of standards and testing 

procedures that began in 2007 reduced PM from heavy-duty highway engines and also reduced 

highway diesel fuel sulfur content to 15 ppm since the sulfur damages emission control devices. 

The total program is expected to achieve a 90% reduction in PM emissions and a 95% reduction 

 

16 Fact Sheets, Office of Transportation and Air Quality, EPA-420-F-14-008 and EPA-420-F-14-009, March 2014.

17 See U.S. EPA, http://www.epa.gov/otaq/tier3.htm.

18 See U.S. EPA, http://www.epa.gov/otaq/climate/regs-light-duty.htm.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 21

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

in NOx emissions for these new engines using low-sulfur diesel, compared to engines using 

higher-content sulfur diesel. These emission reductions are federally enforceable.

Large Nonroad Diesel Engines Rule

In May 2004, the EPA promulgated new rules for large nonroad diesel engines, such as those 

used in construction, agricultural and industrial equipment, to be phased in between 2008 and 

2014. The nonroad diesel rules also reduced the allowable sulfur in nonroad diesel fuel to 15 

ppm. Prior to the fuel standard change, nonroad diesel fuel averaged about 3,400 ppm sulfur. 

The combined engine and fuel rules are expected to reduce NOx and PM emissions from large 

nonroad diesel engines by over 90%.

19

 These emission reductions are federally enforceable.

Medium- and Heavy-Duty Vehicle Fuel Consumption and GHG Standards

In September 2011, the EPA and the NHTSA promulgated joint rules to reduce GHG emissions 

and improve fuel efficiency of combination tractor trucks, heavy-duty pickups and vans, and

vocational trucks beginning with model year 2014 and applying to all model years by 2018. 

Depending on truck type, the on-road vehicles must achieve from a 7% to 20% reduction in CO2

emissions and fuel consumption from the 2010 base year. The decrease in fuel consumption will 

result in a 7% to 20% decrease in NOx emissions.20 These emission reductions are federally 

enforceable.

Nonroad Spark-Ignition Engines and Recreational Engines Standard

The nonroad spark-ignition and recreational engine standards, effective in July 2003, regulates 

NOx, hydrocarbons and CO for groups of previously unregulated nonroad engines. These 

engine standards apply to all new engines sold in the United States and imported after these 

standards began and applies to large spark-ignition engines (forklifts and airport ground service 

equipment), recreational vehicles (off-highway motorcycles and all-terrain-vehicles), and 

recreational marine diesel engines. The regulation varies based upon the type of engine or 

vehicle.

The large spark-ignition engines contribute to ozone formation and ambient CO and PM levels in 

urban areas. Tier 1 of this standard was implemented in 2004 and Tier 2 started in 2007. Like 

the large spark-ignition, recreational vehicles contribute to ozone formation and ambient CO and 

PM levels. For the off-highway motorcycles and all-terrain-vehicles, the exhaust emissions 

standard was phased-in. Fifty percent of model year 2006 engines had to meet the standard and 

for model years 2007 and later, all engines must meet the standard. Recreational marine diesel 

 

19 See U.S. EPA http://transportpolicy.net/index.php?title=US:_Heavy-duty:_Fuel_Consumption_and_GHG

20 Fact Sheet, Office of Transport and Air Quality, EOA-420-F-11-031, August 2011.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 22

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

engines over 37 kilowatts are used in yachts, cruisers, and other types of pleasure craft. 

Recreational marine engines contribute to ozone formation and PM levels, especially in marinas. 

Depending on the size of the engine, the standard began phasing-in in 2006. 

When the nonroad spark-ignition and recreational engine standards are fully implemented in 

2020, an overall 72% reduction in hydrocarbons, 80% reduction in NOx, and 56% reduction in 

CO emissions are expected. These controls will help reduce ambient concentrations of ozone, 

CO, and fine PM.21 These emission reductions are federally enforceable.

CAIR and CSAPR

On May 12, 2005, the EPA promulgated the CAIR which required reductions in emissions of 

NOx and SO2 from large fossil fuel fired EGUs. CAIR also allowed non-EGU industrial boilers 

to participate in the program to meet their NOx SIP Call requirements.22 The U.S. Court of 

Appeals for the D.C. Circuit ruled on petitions for review of CAIR and CAIR Federal 

Implementation Plans (FIPs), including their provisions establishing the CAIR NOx annual and 

ozone season and SO2 trading programs. On July 11, 2008, the Court issued an opinion vacating 

and remanding these rules. However, parties to the litigation requested rehearing of aspects of 

the Court's decision, including the vacatur of the rules. On December 23, 2008, the Court 

remanded the rules to the EPA without vacating them. The December 23, 2008 ruling left CAIR 

in place until the EPA issued a new rule to replace CAIR in accordance with the July 11, 2008 

decision.

The EPA issued CSAPR in July 2011 to address CAA requirements concerning interstate 

transport of air pollution and to replace the previous CAIR which the D.C. Circuit remanded to 

the EPA for replacement. Following the original rulemaking, CSAPR was amended by three 

further rules known as the Supplemental Rule, the First Revisions Rule, and the Second 

Revisions Rule. As amended, CSAPR requires 28 states to limit their state-wide emissions of 

SO2 and/or NOx in order to reduce or eliminate the states’ contributions to fine PM and/or 

ground-level ozone pollution in other states. The emissions limitations are defined in terms of 

maximum state-wide “budgets” for emissions of annual SO2, annual NOx, and/or ozone-season 

NOx by each state’s large EGUs. 

As the mechanism for achieving compliance with the emissions limitations, CSAPR establishes 

FIPs that require large EGUs in each affected state to participate in one or more new emissions 

trading programs that supersede the existing CAIR emissions trading programs. Non-EGU 

 

21 Final Rule: Control of Emissions from Nonroad Large Spark-Ignition Engines, and Recreational Engines (Marine 

and Land-Based), 67 FR 68242.

22 In 2009, the NOx SIP Call program was replaced by CAIR.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 23

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

boilers are not able to participate in CSAPR, resulting in a group of “orphaned” industrial units 

that are still subject to the NOx SIP Call. Interstate trading of CSAPR’s emission allowances is 

permitted, but the rule includes “assurance provisions” designed to ensure that individual states’ 

emissions do not exceed the states’ respective emissions budgets. CSAPR allows states to elect 

to revise their SIPs to modify or replace the FIPs while continuing to rely on the rule’s trading 

programs for compliance with the emissions limitations, and establishes certain requirements and 

deadlines related to those optional SIP revisions. The rule also contains provisions that sunset 

CAIR compliance requirements on a schedule coordinated with the implementation of CSAPR 

compliance requirements. 

Certain industry and state and local government petitioners challenged CSAPR in the D.C. 

Circuit and filed motions seeking a stay of the rule pending judicial review. On December 30, 

2011, the Court granted a stay of the rule, ordering the EPA to continue administering CAIR on 

an interim basis. In a subsequent decision on the merits, the Court vacated CSAPR based on a 

subset of petitioners’ claims, but on April 29, 2014, the U.S. Supreme Court reversed that 

decision and remanded the case to the D.C. Circuit for further proceedings. Throughout the 

initial round of D.C. Circuit proceedings and the ensuing Supreme Court proceedings, the stay 

remained in place and the EPA has continued to implement CAIR. Following the Supreme 

Court decision, in order to allow CSAPR to replace CAIR in an equitable and orderly manner 

while further D.C. Circuit proceedings are held to resolve petitioners’ remaining claims, the EPA 

filed a motion asking the D.C. Circuit to lift the stay and to toll by three years all CSAPR 

compliance deadlines that had not passed as of the date of the stay order. On October 23, 2014, 

the Court granted the EPA’s motion. 

CSAPR will take effect starting January 1, 2015 for SO2 and annual NOx, and May 1, 2015 for 

ozone season NOx. Combined with other final state and EPA actions, the CSAPR will reduce 

power plant SO2 emissions by 73% and NOx emissions by 54% from 2005 levels in the CSAPR 

region.

23

 The emission reductions will be federally enforceable.

TVA Consent Decree

In January 2009 a federal court found that four TVA coal-fired generating stations were creating 

a public nuisance in North Carolina. The judge ordered that each unit of each facility install 

modern pollution controls for SO2 and NOx and meet emission limits that are consistent with the 

continuous operation of such controls. The court ordered that TVA meet these limits on a 

staggered schedule ending in 2013. In July 2010 an appeals court reversed the decision. 

 

23 Interim Final Rule: Rulemaking To Amend Dates in Federal Implementation Plans Addressing Interstate 

Transport of Ozone and Fine Particulate Matter, 79 FR 71663.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 24

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

In April 2011 North Carolina, TVA, and several other parties agreed to a comprehensive 

settlement of a variety of air pollution allegations. The detailed settlement would (1) subject SO2

and NOx emissions at all of TVA’s coal-fired facilities to system-wide caps that decline on an 

annual basis to permanent levels of 110,000 tons of SO2 in 2019 and 52,000 tons of NOx in 

2018; (2) require TVA to install modern pollution controls on or shutdown the majority of its 

coal-fired units; and (3) require TVA to pay North Carolina $11.2 million to fund mitigation 

projects in North Carolina. The settlement is being successfully implemented, including the 

provision of funds directly to North Carolina for approved projects.

24

 These emission reductions 

are federally enforceable.

Boiler NESHAP

The NESHAP for the industrial, commercial and institutional boiler source category is applicable 

to boilers and process heaters burning natural gas, coal, oil or biomass. Boilers must comply 

with the NESHAP by January 31, 2016 for all states except North Carolina (see state control 

measure Section 3.2.2 below for further discussion) and by May 2019 for boilers in North 

Carolina. The NESHAP contains work practice standards such as annual boiler tune ups for 

most boilers. There are also emissions standards for the largest emitting boilers (<1% of all 

boilers) including a CO standard that is a surrogate for gas-phase hazardous air pollutants

(HAPs) and VOC. There is estimated to be a small reduction in VOC emissions due to the 

NESHAP.25 These new emission reductions are federally enforceable.

RICE NESHAP

The RICE NESHAP applies to stationary engines burning natural gas and diesel fuels that 

generate electricity and power equipment at industrial, agricultural, oil and gas production, 

power generation and other facilities. RICE owners and operators had to comply with the 

NESHAP by May 3, 2013. The NESHAP contains work practice standards such as engine 

maintenance, requires ultralow-sulfur diesel fuel for some engines, and requires the use of 

catalytic converters on larger engines. There is estimated to be a slight reduction in VOC 

emissions due to the NESHAP.26 These emission reductions are federally enforceable.

Utility MATS and NSPS Rules

On February 16, 2012, the EPA published final rules for both the (1) MATS for new and existing 

coal- and oil-fired EGUs and (2) NSPS for fossil-fuel fired electric utility, industrial-

 

24 http://www.ncdoj.gov/getdoc/bdf66401-8137-4be2-bd20-57e89b570c1a/TVA-signed-consent-decree.aspx.

25 See U.S. EPA http://www.epa.gov/ttn/atw/boiler/boilerpg.html.

26 See U.S. EPA http://www.epa.gov/ttn/atw/icengines/.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 25

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

commercial-institutional and small industrial-commercial-institutional steam generating units.27 

The MATS reduce emissions of toxic air pollutants from EGUs larger than 25 megawatts that 

burn coal or oil for the purpose of generating electricity for sale and distribution through the 

national electric grid to the public. For the NSPS, the EPA revised the standards that new coaland oil-fired power plants must meet for NOx, SO2, and PM. 

Following promulgation of the final rules, the EPA received petitions for reconsideration of 

various provisions of both rules, including requests to reconsider the work practice standards 

applicable during startup periods and shutdown periods that were included in the final rule. The 

EPA granted reconsideration of the startup and shutdown provisions because the public was not 

provided an opportunity to comment on the work practice requirements contained in the final 

rule. On November 30, 2012, the EPA published a proposed rule reconsidering certain new 

source standards issued in MATS and the startup and shutdown provisions in MATS and the 

Utility NSPS.

28 The EPA proposed certain minor changes to the startup and shutdown 

provisions contained in the 2012 final rule based on information obtained in the petitions for 

reconsideration. On April 24, 2013, the EPA took final action on the new source standards that 

were reconsidered and also the technical corrections contained in the November 30, 2012, 

proposed action. 29 The EPA did not take final action on the startup and shutdown provisions, 

and, on June 25, 2013, the EPA added new information and analysis to the docket and reopened 

the public comment period for the proposed revisions to the startup and shutdown provisions in 

MATS and the startup and shutdown provisions related to the PM standard in the Utility NSPS.

30

 The EPA took final action on the remaining topics of the reconsideration on November 19, 

2014.31 The compliance date for existing sources is April 16, 2015, while the compliance date 

for new sources is April 16, 2012. 

On November 25, 2014, The U.S. Supreme Court accepted several challenges to the rules 

brought by the utility industry and a coalition of nearly two dozen states. The court will hear 

arguments in the case in the spring and is likely to rule in June 2015.32 While MATS is still 

under court review, and portions of it may be overturned, the rule can be expected to result in the 

reduction of both NOx and SO2 emissions in addition to the reduction in mercury and other air 

toxic emissions. The emission reductions are federally enforceable.

 

27 77 FR 9304.

28 77 FR 71323.

29 78 FR 24073.

30 78 FR 38001.

31 79 FR 68777.

32 Wall Street Journal, Nov. 25, 2014, Supreme Court to Review EPA Rule on Power Plant Emissions, 

http://www.wsj.com/articles/supreme-court-to-review-epa-rule-on-power-plant-emissions1416942022?mod=WSJ_newsreel_6.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 26

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

3.2.2 State Control Measures

North Carolina has adopted a number of regulations, legislation and voluntary programs to 

address pollution issues across the state. These are summarized below. 

Vehicle Emissions Inspection and Maintenance (I/M) Program

The 1999 Clean Air Bill expanded the vehicle emissions I/M program in North Carolina from 9 

counties to 48 counties from July 1, 2002 through January 1, 2006. Vehicles are tested using the 

OBDII, an improved method of testing, which ensures proper emission system operation for 

vehicles and light trucks during their lifetime by monitoring emission-related components and 

systems for malfunction and/or deterioration. An important aspect of OBDII is its ability to 

notify the driver of malfunction and/or deterioration by illuminating the "check engine light". If 

the vehicle is taken to a repair shop in a timely fashion, it can be properly repaired before any 

significant and prolonged emission increase occurs. The previously used tailpipe test (i.e., idle 

test) did not measure NOx emissions; it only tested for VOC and CO emissions. By utilizing the 

OBDII test method, the NOx emissions as well as other pollutants from motor vehicles are 

reduced. The effective dates for the counties in the North Carolina portion of the Charlotte 

nonattainment area are July 1, 2002 for Cabarrus, Gaston, Mecklenburg and Union Counties; 

July 1, 2003 for Iredell and Rowan Counties; and January 1, 2004 for Lincoln County. 

The I/M program rule was submitted to the EPA for adoption into the SIP in August 2002 and 

was federally approved in October 2002. Therefore, these emission reductions are both state and 

federally enforceable. 

On February 5, 2015, the EPA approved a change to North Carolina’s I/M rules triggered by a 

state law which exempted plug-in vehicles and the three newest model year vehicles with less 

than 70,000 miles on their odometers from emission inspection in all areas in North Carolina 

where I/M is required. 33 In North Carolina’s Section 110(l) demonstration, the state showed that 

the change in the compliance rate from 95% to 96% more than compensates for the NOx and 

VOC emissions increase from exempting the newest model year vehicles with less than 70,000 

miles. Based on recent modeling the DAQ completed using the EPA’s MOVES2014 model, 

North Carolina’s current I/M program with the the three newest model year vehicle exemption is 

expected to yield annual I/M emission reduction benefits ranging from 5% to 8% for NOx and 

6% to 8.5% for VOC. The EPA-approved change to the I/M rules was effective March 9, 2015. 

The emissions reductions are state and federally enforceable.

 

33 Approval and Promulgation of Implementation Plans; North Carolina; Inspection and Maintenance Program 

Updates, 80 FR, 6455.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 27

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Clean Smokestacks Act

In June 2002, the North Carolina General Assembly enacted the North Carolina Clean 

Smokestacks Act, which required coal-fired power plants in North Carolina to reduce annual 

NOx emissions by 77% by 2009.34 These power plants were also required to reduce annual SO2

emissions by 49% by 2009 and 74% by 2013. The utilities have reduced NOx emissions by 83% 

and SO2 emissions by 89% relative to 1998 emissions levels. 

With the requirement to meet annual emissions caps and disallowing the purchase of NOx credits 

to meet the caps, the Clean Smokestacks Act reduces NOx emissions beyond the requirements of 

the NOx SIP Call Rule. The CSA emissions caps were submitted to the EPA for adoption into 

the SIP in August 2009 and were approved in September 2011. These regulations are both state 

and federally enforceable.

Boiler NESHAP

Because of delays associated with the EPA’s promulgation of the boiler NESHAP, North 

Carolina adopted and implemented equivalent emission limitations by permit under Section 

112(j) of the CAA.35 These limitations apply to owners and operators of industrial, commercial 

and institutional boiler boilers and process heaters burning natural gas, coal, oil or biomass 

beginning in 2013. This rule reduced uncertainty for owners and operators of affected emission 

units while the EPA resolved legal challenges to the federal rule, reduced emissions from 

affected units three years earlier than the federal rule, and provided the time needed for owners 

and operators to transition to the federal rule requirements beginning in May 2019.36 Although 

the rule establishes limits for reducing HAPs form boilers and process heaters, VOC emissions 

will also be controlled. In the Charlotte area, natural gas fired boilers are the only types of 

emission units affected by this rule. For natural gas fired boilers, VOC emissions are estimated 

to be reduced by 4%. The emission limits associated with this rule are state and federally 

enforceable. 

Transportation Conformity MOAs

Transportation conformity MOAs establish criteria and procedures related to interagency 

consultation, conflict resolution, public participation and enforceability of certain transportation 

related control measures and mitigation measures in the State of North Carolina and its SIP. 

 

34 Air Quality/Electric Utilities Bill (SB 1078), http://daq.state.nc.us/news/leg/.

35 15A NCAC 02D .1109 - 112(j) Case-by-Case Maximum Achievable Control Technology.

36 See U.S. EPA http://www.epa.gov/ttn/atw/boiler/boilerpg.html.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 28

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Transportation conformity is required under section 176(c) of the CAA for nonattainment and 

maintenance areas to ensure that federally supported highway projects, transit projects, and other 

activities are consistent with (conform to) the purpose of the SIP, which is to eliminate or reduce 

the severity and number of violations of the NAAQS and to achieve expeditiously the attainment 

of such standards. In compliance with Section 176(c) of the CAA, North Carolina Department of 

Environment and Natural Resources, Division of Air Quality chose, through rulemaking as 

referenced in 15A North Carolina Administrative Code (NCAC) 02D.2005, to develop 

Conformity MOAs to ensure that interagency consultation procedures for transportation 

conformity are followed.37 The Conformity MOAs were submitted to the EPA on July 12, 2013. 

The USEPA, through direct final rule action, approved a revision to the North Carolina SIP with 

the effective date of February 24, 2014.38

3.3 ADDITIONAL PROGRAMS SUPPORTING MAINTENANCE

This section provides a summary of state and local programs that have been implemented in the 

Charlotte area to maintain compliance with the NAAQS. Although these are important programs 

that help to ensure compliance with the NAAQS, they have not been relied upon as federally 

enforceable measures. 

3.3.1 State Programs Supporting Maintenance

Air Awareness Program

The DAQ has found that the most effective outreach programs are performed by locally-based 

personnel who can work closely with members of the local community. The DAQ has 

contracted with MCAQ to manage the Charlotte area North Carolina Air Awareness (NCAA) 

program since its inception in 1997. Charlotte area NCAA has conducted educational outreach 

with the general public, built strong working relationships with regional interest groups, and 

developed communication resources for business coalition members. Coalition activities are 

designed to communicate air quality information, including the forecast, and promote voluntary 

emissions reduction programs. The business coalition includes partnerships with private 

businesses and civic organizations. These efforts are important for maintaining compliance with 

the NAAQS. Under MCAQ’s management, Charlotte area NCAA has established itself as a 

leader in advocating for voluntary pollution reduction efforts throughout the state’s only ozone 

nonattainment region. 

 

37 http://www.ncair.org/rules/rules/D2005.pdf.

38 78 FR 73266-78272.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 29

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Grant Program

Since 1995, the DAQ has offered multiple forms of grant funding to help cover the costs 

associated with emission reduction projects. These projects include diesel engine replacements, 

diesel oxidation catalyst retrofits, marine diesel repowers, replacing gasoline vehicles with 

electric vehicles and many more. One source of funding is the North Carolina Mobile Source

Emissions Reduction Grants funded by gasoline tax receipts. The Mobile Source Emissions 

Reduction Grant program has awarded grants to a number of businesses, cities, counties and 

school districts that have ranged from the installation of Diesel Oxidation Catalysts (DOCs) or 

Diesel Particulate Filters (DPFs) on their diesel equipment to non-diesel emission reduction 

projects like purchase of electric vehicles. The DAQ has also received federal funds from the 

Diesel Emissions Reduction Act (DERA) and the American Recovery and Reinvestment Act 

(ARRA) to fund diesel emission reducing projects. The DERA and ARRA funds that the DAQ 

has received have been used to retrofit, repower or replace existing diesel engines from on-road 

and nonroad mobile source vehicles/equipment. Even though these emission reductions are 

voluntary and not enforceable, they are still considered permanent reductions.

Open Burning Rule

The North Carolina open burning rule prohibits the burning of man-made materials statewide. 

The rule also prohibits open burning of yard waste and land clearing debris on forecasted code 

orange or higher "air quality action days" for those counties for which the DAQ or local air 

programs forecast ozone or fine PM.39 The open burning rule reduces PM, SO2, CO, NOx, and 

VOC emissions. This rule is state enforceable.

Idle Reduction Regulation

The North Carolina Environmental Management Commission adopted the Heavy-Duty Vehicle 

Idling Restrictions rule to reduce unnecessary idling of heavy-duty trucks on July 9, 2009 and the 

rule became effective on July 10, 2010. This rule generally prevents any person who operates a 

heavy-duty vehicle to cause, let, permit, suffer or allow idling for a period of time in excess of 5 

consecutive minutes in any 60 minute period. This rule is state enforceable.

3.3.2 Local Programs Supporting Maintenance

Mobile Source Emissions Reduction Grants

In the Charlotte area, between 2011 and 2013, with funding from a settlement, a nonroad 

equipment repower was funded. This project resulted in significant fuel savings and reductions 

in NOx and PM2.5 emissions.

 

39 15A NCAC 02Q.1900 – Open Burning.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 30

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

GRADE Program 

In 2007, MCAQ initiated an air pollution control program called GRADE designed to reduce 

NOx emissions in the Charlotte nonattainment area. Funded by federal, state and local county 

grant money, GRADE provides businesses and organizations financial incentives to replace or 

repower heavy-duty non-road equipment with newer, cleaner, less polluting engines. 

GRADE has funded cost effective emission reduction projects operating in multiple segments of 

the economy including construction, landfills, timber logging operations, open pit mining, freight 

transportation, and commercial aviation. As of July 31, 2014, GRADE projects have reduced 

over 350 tons of NOx region-wide. 

Open Burning Prohibitions

Mecklenburg County prohibits open burning of any kind year round except under extenuating 

circumstances with an approved burn permit. This prohibition is more stringent than the state’s 

open burning rule and therefore enhances this control measure’s overall benefit to the region. 

The open burning rule reduces emissions of NOx, VOC, CO, PM10 and PM2.5. These emission 

reductions are enforced at the local level.

3.4 EMISSIONS INVENTORIES AND MAINTENANCE DEMONSTRATION

3.4.1 Theory of Approach

There are two basic approaches used to demonstrate continued maintenance. The first is the 

comparison of a projected emissions inventory with a baseline emissions inventory. The second 

approach involves complex analysis using gridded photochemical modeling. The approach used 

by the DAQ is the comparison of emissions inventories for the years 2014 and 2026.

For the maintenance demonstration, the base year of 2014 was chosen since it is a year that falls 

within the attaining design value period of 2012-2014. The maintenance demonstration is made 

by comparing the 2014 baseline summer day emissions inventory to the 2026 projected summer 

day emissions inventory. The baseline summer day emissions inventory represents an emission 

level for a period when the ambient air quality standard was not violated, 2012-2014. If the 

projected emissions remain at or below the baseline emissions, continued maintenance is 

demonstrated and it then follows, if the projected emissions remain at or below the baseline 

emissions, then the ambient air quality standard should not be violated in the future. In addition 

to comparing the final year of the plan, all of the interim years are compared to the 2014 baseline 

to demonstrate that these years are also expected to show continued maintenance of the 2008

8-hour ozone standard.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 31

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

The emissions inventories are comprised of four major types of sources: point, area, on-road

mobile and nonroad mobile. The projected summer day emission inventories have been 

estimated using projected rates of growth in population, traffic, economic activity and other 

parameters. Naturally occurring, or biogenic, emissions are not included in the emissions 

inventory comparison, as these emissions are outside the state’s span of control.

The SCDHEC has developed a redesignation demonstration and maintenance plan for the South 

Carolina portion of the nonattainment area. Contact the SCDHEC for a copy of the South 

Carolina redesignation demonstration and maintenance plan. 

3.4.2 Emission Inventories

The base year and future year emissions inventory for this SIP includes the emissions associated 

with all emission sources in Mecklenburg County and the portion of the other six counties that is 

included in the nonattainment area. For point sources, the location coordinates for each facility 

were mapped using Geographic Information System (GIS) software to identify the facilities 

located within the nonattainment portion of each county. For the on-road mobile, nonroad 

mobile, and area source sectors, total county emissions were multiplied by the population 

percentages for the townships within the nonattainment area to calculate the emissions for the 

nonattainment portion for each county. Table 3.1 shows the population percentages that were 

used to determine emissions contributions for the nonattainment portion of each partial county 

(except for Mecklenburg County). The population percentages were obtained from 

transportation demand modeling (TDM) that the Charlotte Department of Transportation 

completed to develop vehicle miles traveled (VMT) and vehicle speed data used as inputs to the 

on-road model for the base year and each of the future years.

The following provides a brief discussion on the four different man-made emission inventory 

source classifications: (1) stationary point, (2) area, (3) on-road mobile and (4) nonroad mobile.

Table 3.1 Population Percentages Used to Allocate Partial County Emissions

County

Population Percentage

2014 2015 2018 2022 2026

Cabarrus 99.4 99.4 99.5 99.5 99.5

Gaston 92.2 92.4 92.5 92.7 92.9

Iredell 44.2 44.5 45.3 46.1 46.6

Lincoln 83.3 83.3 83.6 83.8 84.1

Rowan 93.9 93.9 93.9 94.0 94.0

Union 87.6 87.5 87.5 87.6 87.6
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 32

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Point sources are those stationary sources that require an air permit to operate. In general, these 

sources have a potential-to-emit more than five tons per year of a criteria air pollutant or its 

precursors from a single facility. The source emissions are tabulated from data collected by 

direct on-site measurements of emissions or mass balance calculations utilizing emission factors 

from the EPA’s AP-42 or stack test results. There are usually several emission sources for each 

facility. Emission data are collected for each point source at a facility and reported to the DAQ 

through its on-line system. 

Airports and rail yards are not required to have air quality permits for construction and operation 

(although they could have equipment such as a boiler or generator that requires a permit). They 

do have fixed and known locations and their emissions quantities can be comparable to industrial 

sources so, for purposes of the EPA’s National Emission Inventory (NEI), they are included in 

the point source inventory even though they are traditionally considered nonroad sources. 

For EGUs, base year 2014 average July day emissions were obtained from the EPA’s CAMD for 

the three Duke Energy Carolinas EGU facilities located in the Charlotte area (i.e., Allen in 

Gaston County, Lincoln in Lincoln County, and Buck in Rowan County). For the remaining

Title V sources, the latest data available were the 2013 emissions data that the sources submitted 

to the DAQ, and, for these sources, 2013 emissions were used to represent 2014 base year 

emission. For sources that emit less than 25 tons per year of NOx or VOC and are subject to 

emissions statements requirements, the latest data available were the 2013 emissions data that the 

sources submitted to the DAQ, and, for these sources, 2013 emissions were used to represent 

2014 base year emission. The Charlotte nonattainment area includes some small sources that 

report emissions to the DAQ once every five years and, for these sources, the most recently 

reported data was used and assumed to be equivalent to 2014 since the emissions from these 

small sources do not vary much from year to year.

40 The DAQ reviewed recent historical 

emissions data (i.e., 2010 - 2013) for non-EGU Title V and emissions sources subject to the 

emissions statements requirements. Based on this review, the DAQ decided that 2013 emissions 

should be used to represent 2014 emissions due to the uncertainty associated with applying 

regional growth factors to forecast emissions for one year. 

For each of the three EGU facilities located in the Charlotte area, Duke Energy Carolinas 

provided the DAQ with the projected emissions for July for each facility for each future year. 

Projected emissions for July were divided by the number of operating days during July to 

estimate the average summer July day emissions. The forecast reflects compliance with the 

North Carolina Clean Smokestacks Act and the MATS rule; however, it does not reflect any 

 

40 North Carolina permit renewal intervals for small sources changed from every five years to every eight years, 

effective 2014. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 33

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

additional controls to comply with CSAPR. Therefore, if additional controls are installed to 

comply with CSAPR the emissions forecast may be lower than reflected in the forecast for the 

three EGU facilities.

Non-EGU point sources future year emission were adjusted by growth factors based on North 

American Industry Classification System (NAICS) codes generated using growth patterns 

obtained from the Annual Energy Outlook 2014 reference case and state employment forecasts.41 

However, for EGUs, the estimated projected future year emissions were based on forecast data

provided by the utility company. 

The inventory includes 20 natural gas fired boilers that, beginning in 2014, are subject to 

equivalent emission limitations by permit that North Carolina established per Section 112(j) of 

the CAA. Because the base year inventory for these boilers did not include the effects of 

controls installed to comply with the NESHAP, a VOC control factor was applied to future year 

emissions to account for the effects of the controls. A NOx control factor was not applied to the 

future year emissions for the boilers because the NESHAP is not expected to significantly affect 

NOx emissions. No other control factors were applied to point source emissions for the future 

year inventories. 

Aircraft future year emissions were generated by using growth factors produced by running the 

Federal Aviation Administration’s (FAA) Terminal Area Forecast (TAF) model. For each 

aircraft category, the 2011 operations estimate was divided into the operations estimate of later 

years to calculate the growth factor. 

Rail yard future year emissions were estimated by using growth factors calculated using national 

fuel use estimates for freight and for intercity passenger service found on Table 46 of the Energy 

Information Administration’s (EIA) Annual Energy Outlook,2014. Rail yard future year 

emission were also adjusted by control factors calculated using recommended emission factors 

for NOx and hydrocarbons (virtually the same as VOC) from Emission Factors for Locomotives, 

EPA-420-F-09-025.

For detailed discussion on how the point sources emission inventory was developed, see 

Appendix B.1. A summary of the point source emissions is presented in Table 3.2 and Table 3.3. 

The emissions are presented in a ton per summer day basis.

 

41 Annual Energy Outlook 2014, released May 7, 2014, http://www.eia.gov/forecasts/aeo/.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 34

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 3.2 Point Source NOx Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 1.72 1.80 1.94 2.07 2.20

Gaston*¥16.50 17.25 10.72 16.16 5.29

Iredell* 2.02 2.03 2.04 2.04 2.05

Lincoln* 0.18 0.84 0.95 1.20 0.73

Mecklenburg 8.56 8.77 9.46 10.45 12.00

Rowan* 2.80 3.16 3.51 3.71 3.76

Union* 0.59 0.62 0.66 0.70 0.72

Total 32.38 34.47 29.28 36.33 26.75

* Emissions for portion of county included in nonattainment area. Totals include emissions associated 

with stationary point sources, aircraft, and rail yards. 

¥ For Gaston County, the fluctuation in NOx emissions from 2014 through 2026 are primarily associated 

with the emissions forecast that Duke Energy Carolinas provided for the G.G. Allen power plant.

Table 3.3 Point Source VOC Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 0.99 1.03 1.15 1.17 1.24

Gaston* 1.82 1.90 2.06 2.16 2.22

Iredell* 0.68 0.68 0.69 0.69 0.69

Lincoln* 1.50 1.54 1.72 1.83 1.94

Mecklenburg 3.36 3.45 3.73 4.02 4.36

Rowan* 2.30 2.40 2.70 2.85 3.14

Union* 1.38 1.42 1.57 1.64 1.74

Total 12.03 12.42 13.62 14.36 15.33

* Emissions for portion of county included in nonattainment area. Totals include emissions associated 

with stationary point sources, aircraft, and rail yards. 

Area sources are those stationary sources whose emissions are relatively small but due to the 

large number of these sources, the collective emissions could be significant (i.e., dry cleaners, 

service stations, etc.). For area sources, emissions are estimated by multiplying an emission 

factor by some known indicator of collective activity such as production, number of employees, 

or population. These types of emissions are estimated on the county level. For the future year 

inventory, base year area source emissions are changed by projected population or employment 

growth. For detailed discussion on how the area source emission inventory was developed, see 

Appendix B.2. A summary of the area source emissions is presented in Table 3.4 and Table 3.5. 

The emissions are presented in a ton per summer day basis. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 35

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 3.4 Area Source NOx Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 0.97 0.96 0.96 0.96 0.96

Gaston* 1.30 1.28 1.28 1.29 1.29

Iredell* 0.54 0.53 0.54 0.56 0.55

Lincoln* 0.40 0.40 0.40 0.40 0.40

Mecklenburg 6.07 6.01 6.01 6.01 6.00

Rowan* 0.87 0.86 0.85 0.85 0.85

Union* 1.25 1.24 1.24 1.24 1.23

Total 11.40 11.28 11.28 11.31 11.28

* Emissions for portion of county included in nonattainment area.

Table 3.5 Area Source VOC Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 5.09 5.13 5.26 5.42 5.59

Gaston* 5.24 5.30 5.43 5.60 5.75

Iredell* 3.08 3.13 3.26 3.43 3.58

Lincoln* 2.56 2.57 2.64 2.74 2.82

Mecklenburg 20.59 20.77 21.19 21.73 22.26

Rowan* 5.23 5.28 5.40 5.56 5.72

Union* 6.09 6.12 6.26 6.43 6.60

Total 47.88 48.30 49.44 50.91 52.32

* Emissions for portion of county included in nonattainment area.

For highway mobile sources, the EPA’s Motor Vehicle Emission Simulator (MOVES2014) 

mobile model was run to generate emissions. The MOVES2014 model includes the road class 

VMT as an input file and can directly output the estimated emissions. For the projected years’ 

inventories, the highway mobile sources emissions are calculated by running the MOVES mobile 

model for the future year with the projected VMT to generate emissions that take into 

consideration expected federal tailpipe standards, fleet turnover and new fuels. For detailed 

discussion on how the on-road mobile emission inventory was developed, see Appendix B.3. A 

summary of the on-road mobile source emissions is presented in Table 3.6 and Table 3.7. The 

emissions are presented in a ton per summer day basis.

Nonroad mobile sources, also referred to as off-road mobile sources, are equipment that can 

move but do not use the roadways (i.e., lawn mowers, construction equipment, railroad 

locomotives, etc.). The emissions from this category are calculated using the EPA’s 

NONROAD2008a model, with the exception of the railroad locomotives. The railroad 

locomotive emissions are estimated by taking activity and multiply by an emission factor. These 

emissions are also estimated at the county level. For the projected years’ inventories, the 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 36

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

emissions are estimated using the EPA’s NONROAD2008a model. For detailed discussion on 

how the nonroad mobile emission inventory was developed, see Appendix B.4. A summary of 

the nonroad mobile source emissions is presented in Table 3.8 and Table 3.9. The emissions are 

presented in a ton per summer day basis. 

Table 3.6 On-road Mobile Source NOx Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 6.60 5.93 3.94 2.79 1.86

Gaston* 8.11 7.26 4.62 3.04 1.98

Iredell* 3.36 3.05 2.05 1.41 0.93

Lincoln* 3.00 2.75 1.84 1.23 0.76

Mecklenburg 26.99 24.20 14.39 9.65 6.85

Rowan* 6.42 5.75 3.73 2.56 1.59

Union* 5.67 5.14 3.41 2.28 1.51

Total 60.15 54.08 33.98 22.96 15.48

* Emissions for portion of county included in nonattainment area.

Table 3.7 On-road Mobile Source VOC Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 4.15 3.89 3.01 2.53 2.04

Gaston* 4.61 4.29 3.08 2.32 1.73

Iredell* 1.95 1.82 1.40 1.10 0.82

Lincoln* 1.91 1.81 1.37 1.07 0.79

Mecklenburg 14.40 13.41 10.09 8.22 6.67

Rowan* 3.76 3.48 2.57 1.93 1.41

Union* 3.54 3.30 2.54 2.04 1.56

Total 34.32 32.00 24.06 19.21 15.02

* Emissions for portion of county included in nonattainment area.

Table 3.8 Nonroad Mobile Source NOx Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 2.20 2.04 1.65 1.34 1.16

Gaston* 1.98 1.83 1.49 1.23 1.08

Iredell* 0.94 0.88 0.72 0.58 0.51

Lincoln* 0.78 0.72 0.59 0.49 0.42

Mecklenburg 15.09 13.99 11.36 9.20 8.11

Rowan* 1.65 1.53 1.26 1.04 0.89

Union* 3.62 3.36 2.72 2.19 1.86

Total 26.26 24.35 19.79 16.07 14.03

* Emissions for portion of county included in nonattainment area.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 37

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 3.9 Nonroad Mobile Source VOC Emissions (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 1.27 1.22 1.17 1.19 1.24

Gaston* 1.29 1.25 1.14 1.12 1.15

Iredell* 0.62 0.59 0.52 0.49 0.49

Lincoln* 0.58 0.55 0.48 0.46 0.46

Mecklenburg 11.75 11.53 11.01 11.11 11.51

Rowan* 1.30 1.22 1.05 0.96 0.94

Union* 2.08 2.01 1.92 1.93 2.00

Total 18.89 18.37 17.29 17.26 17.79

* Emissions for portion of county included in nonattainment area.

3.4.3 Summary of Emissions

The sum totals of the man-made emissions for the North Carolina portion of the Charlotte 

nonattainment area are tabulated in Table 3.10 and Table 3.11.

Table 3.10 Total Man-Made NOx Emissions for the North Carolina Portion of the 

Charlotte Nonattainment Area (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 11.49 10.73 8.49 7.16 6.18

Gaston* 27.89 27.62 18.11 21.72 9.64

Iredell* 6.86 6.49 5.35 4.59 4.04

Lincoln* 4.36 4.71 3.78 3.32 2.31

Mecklenburg 56.71 52.97 41.22 35.31 32.96

Rowan* 11.74 11.30 9.35 8.16 7.09

Union* 11.13 10.36 8.03 6.41 5.32

Total 130.18 124.18 94.33 86.67 67.54

* Emissions for portion of county included in nonattainment area.

Table 3.11 Total Man-Made VOC Emissions for the North Carolina Portion of the 

Charlotte Nonattainment Area (tons/day)

County 2014 2015 2018 2022 2026

Cabarrus* 11.50 11.27 10.59 10.31 10.11

Gaston* 12.96 12.74 11.71 11.20 10.85

Iredell* 6.33 6.22 5.87 5.71 5.58

Lincoln* 6.55 6.47 6.21 6.10 6.01

Mecklenburg 50.10 49.16 46.02 45.08 44.80

Rowan* 12.59 12.38 11.72 11.30 11.21

Union* 13.09 12.85 12.29 12.04 11.90

Total 113.12 111.09 104.41 101.74 100.46

* Emissions for portion of county included in nonattainment area.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 38

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

3.4.4 Maintenance Demonstration

As discussed above, maintenance is demonstrated when the future year’s total man-made 

emissions are less than the 2014 baseline emissions. Table 3.12 summarizes the NOx and VOC

emissions for the North Carolina portion of the Charlotte nonattainment area. The difference 

between the base year and the final year illustrates that the continued maintenance of the 2008 8-

hour ozone NAAQS is expected. This is further supported by two modeling studies summarized 

in the following section. 

Table 3.12 Maintenance Demonstration for North Carolina Portion of the 

Charlotte Nonattainment Area

Year NOx (tons/day) VOC (tons/day)

2014 130.18 113.12

2015 124.18 111.09

2018 94.33 104.41

2022 86.67 101.74

2026 67.54 100.46

Difference from

2014 to 2026 -62.64 -12.66

The difference between the attainment level of emissions (2014) from all man-made sources and 

the projected level of emissions (2026) from all man-made sources in the nonattainment area is 

considered the “safety margin”. The safety margin for the North Carolina portion of the 

nonattainment area is summarized in Table 3.13.

Table 3.13 Safety Margin for North Carolina Portion of the Charlotte Nonattainment Area

Year NOx (tons/day) VOC (tons/day)

2014 N/A N/A

2015 -6.00 -2.03

2018 -35.85 -8.71

2022 -43.51 -11.38

2026 -62.64 -12.66
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 39

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

3.4.5 National and Regional Air Quality Assessments in Future Years

The Southeastern States Air Resource Managers (SESARM) conducted a Southeastern 

Modeling, Analysis and Planning (SEMAP) project to produce technical analyses to assist

member states in developing SIPs for ozone and PM2.5, and in the demonstration of reasonable 

progress for the regional haze rule. Photochemical modeling predicts that ozone in the Charlotte 

nonattainment area will be well below 0.075 ppm in 2018. Base and future design values are 

shown in Table 3.14. It should be noted that the benefits of Tier 3 engine and fuel standards

were not included in these results.

Table 3.14 Eight-hour Design Values from SEMAP Photochemical Modeling

Monitor County

2007 Base 

Design Value, 

ppm

2018 Future 

Design Value, 

ppm

Relative 

Reduction 

Factor1

371090004 Lincoln 0.080 0.064 0.7977

371190041 Mecklenburg 0.087 0.070 0.8149

371191005 Mecklenburg 0.079 0.065 0.8224

371191009 Mecklenburg 0.091 0.072 0.7927

371590021 Rowan 0.086 0.067 0.781

371590022 Rowan 0.087 0.068 0.7888

371790003 Union 0.079 0.062 0.7869

Source: Southeastern States Air Resource Managers (SESARM); Southeastern Modeling, Analysis and 

Planning (SEMAP) study, http://semap.ce.gatech.edu/sites/default/files/files/projections/base2018b-O3-

DVFs-DDVFs-for-4configs.xls.

1 The Relative Reduction Factor is the ratio of the future modeled ozone concentration divided by the 

base modeled ozone concentration. The future design value is computed by multiplying the Relative 

Reduction Factor and the base design value.

The EPA used photochemical modeling to assess the impacts of the federal Tier 3 rule. Ozone 

design values in 2018 within the Charlotte nonattainment area are predicted to be below 0.075 

ppm in the reference case, and even lower when Tier 3 controls are included. The downward 

trend in ozone continues out to 2030. The EPA Tier 3 ozone modeling results are shown in 

Table 3.15. 

Table 3.15 Eight-hour Design Values Scenarios from EPA Tier 3 Photochemical Modeling

County

2007 

Baseline 

Design 

Value, ppm

2018 

Reference 

Design 

Value, ppm

2018 Tier 3 

Control 

Design 

Value, ppm

2030 

Reference 

Design 

Value, ppm

2030 Tier 3 

Control 

Design 

Value, ppm

Lincoln 0.080 0.064 0.063 0.060 0.058

Mecklenburg 0.091 0.073 0.072 0.069 0.067

Rowan 0.087 0.069 0.068 0.065 0.063

Union 0.079 0.062 0.061 0.058 0.056

Source: US EPA http://www.epa.gov/otaq/documents/tier3/454r14002.pdf. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 40

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

3.5 CONTINGENCY PLAN

3.5.1 Overview

The two main elements of the North Carolina contingency plan are tracking and triggering 

mechanisms to determine when contingency control measures are needed and a process of 

developing and adopting appropriate control measures. There will be three potential triggers for 

the contingency plan. The primary trigger of the contingency plan will be a violation of the 2008

8-hour ozone NAAQS at any of the Charlotte area monitors. The secondary trigger will be a 

monitored air quality pattern that suggests an actual 2008 8-hour ozone NAAQS violation may 

be imminent. The tertiary trigger will be a monitored fourth highest exceedance of the NAAQS. 

Upon either the primary or secondary triggers being activated, the DAQ, working in consultation 

with the SCDHEC and the MCAQ local program, will commence analyses to determine what 

additional measures, if any, will be necessary to attain or maintain the 2008 8-hour ozone 

standard. If activation of either the primary or secondary triggers occurs, this plan provides a 

regulatory adoption process for revising emission control strategies. Activation of the tertiary 

trigger will result in an analysis to understand the cause of the exceedance and to identify 

voluntary measures if needed. 

In addition, there will be a tracking mechanism that requires a comparison of the actual 

emissions inventory submitted under the Air Emission Reporting Rule (AERR) to the projected 

inventory, and to the attainment year inventory contained in this maintenance plan. The AERR 

reporting years coincide with the base year (2014) and final year (2026) for this maintenance 

demonstration. In addition, the AERR reporting years will occur at 3-year intervals, thus 

enabling the comparison of actual emissions developed for the AERR to the projected emissions 

for the interim years presented in this maintenance demonstration. 

3.5.2 Contingency Plan Triggers

The primary trigger of the contingency plan will be a violation of the 2008 8-hour ozone 

standard, or when the three-year average of the 4th highest values is equal to or greater than 0.076

ppm at a monitor in the Charlotte nonattainment area. The trigger date will be 60 days from the 

date that the state observes a 4th highest value that, when averaged with the two previous ozone 

seasons’ fourth highest values, would result in a three-year average equal to or greater than 0.076

ppm.

The secondary trigger will apply where no actual violation of the 2008 8-hour ozone standard 

has occurred, but where the state finds monitored ozone levels indicating that an actual ozone 

NAAQS violation may be imminent. A pattern will be deemed to exist when there are two 

consecutive ozone seasons in which the 4th highest values are 0.076 ppm or greater at a single 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 41

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

monitor within the Charlotte nonattainment area. The trigger date will be 60 days from the date 

that the state observes a 4th highest value of 0.076 ppm or greater at a monitor for which the 

previous season had a 4th highest value of 0.076 ppm or greater.

Similarly, the tertiary trigger will not be an actual violation of the 2008 8-hour ozone standard. 

This trigger will be a first alert as to a potential air quality problem on the horizon. The trigger 

will be activated when a monitor in the Charlotte nonattainment area has a 4th highest value of 

0.076 ppm or greater, starting the first year after the maintenance plan has been approved. The 

trigger date will be 60 days from the date that the state observes a 4th highest value of 0.076 ppm 

or greater at any monitor. 

3.5.3 Action Resulting From Trigger Activation

Once the primary or secondary trigger is activated, the Planning Section of the DAQ, in 

consultation with the SCDHEC and MCAQ, shall commence analyses including trajectory 

analyses of high ozone days, and emissions inventory assessment to determine those emission 

control measures that will be required for attaining or maintaining the 2008 8-hour ozone 

standard. By May 1 of the year following the ozone season in which the primary or secondary 

trigger has been activated, North Carolina will complete sufficient analyses to begin adoption of 

necessary rules for ensuring attainment and maintenance of the 2008 8-hour ozone NAAQS. 

The rules would become state effective by the following January 1, unless legislative review is 

required.

The measures that will be considered for adoption upon a trigger of the contingency plan 

include: NOx Reasonably Available Control Technology on stationary sources with a potential 

to emit less than 100 tons per year in the North Carolina portion of the Charlotte nonattainment 

area, diesel I/M program, implementation of diesel retrofit programs, including incentives for 

performing retrofits, and additional controls in upwind areas.

The DAQ commits to implement within 24 months of a primary or secondary trigger, or as 

expeditiously as practicable, at least one of the control measures listed above or other 

contingency measures that may be determined to be more appropriate based on the analyses 

performed.

Once the tertiary trigger is activated, the Planning Section of the DAQ, in consultation with the 

SCDHEC and MCAQ, shall commence analyses including meteorological evaluation, trajectory 

analyses of high ozone days, and emissions inventory assessment to understand why a 4th highest 

exceedance of the standard has occurred. Once the analyses are completed, the DAQ will work 

with SCDHEC, MCAQ and the local air awareness program to develop an outreach plan 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 42

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

identifying any additional voluntary measures that can be implemented. If the 4th highest 

exceedance occurs early in the season, the DAQ will work with entities identified in the outreach 

plan to determine if the measures can be implemented during the current season, otherwise, DAQ

will work with SCDHEC, MCAQ and the local air awareness coordinator to implement the plan 

for the following ozone season.

3.5.4 Tracking Program for Ongoing Maintenance 

In addition to the measures listed above, emissions inventory comparisons will be carried out. 

The large stationary sources are required to submit an emissions inventory annually to the DAQ

or MCAQ. The DAQ will commit to review these emissions inventories to determine if an 

unexpected growth in NOx emissions in the Charlotte area may endanger the maintenance of the 

2008 8-hour ozone standard. Additionally, as new VMT data are provided by the NCDOT, the 

DAQ commits to review these data and determine if any unexpected growth in VMT may 

endanger the maintenance of the 2008 8-hour ozone standard.

Additionally, under the AERR the DAQ is required to develop a comprehensive, annual, 

statewide emissions inventory every three years and is due 12 to 18 months after the completion 

of the inventory year. The AERR inventory years match the base year and final year of the 

inventory for the maintenance plan, and are within one or two years of the interim inventory 

years of the maintenance plan. Therefore, the DAQ commits to compare the AERR inventories 

as they are developed with the maintenance plan to determine if additional steps are necessary 

for continued maintenance of the 2008 8-hour ozone standard in this area. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 43

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

4.0 MOTOR VEHICLE EMISSIONS BUDGET FOR CONFORMITY

4.1 TRANSPORTATION CONFORMITY

The purpose of transportation conformity is to ensure that federal transportation actions 

occurring in nonattainment and maintenance areas do not hinder the area from attaining and 

maintaining the 2008 8-hour ozone standard. This means that the level of emissions estimated 

by the NCDOT or the metropolitan planning organizations for the TIP and Metropolitan 

Transportation Plan (MTP) must not exceed the motor vehicle emissions budgets (MVEBs) as 

defined in this maintenance plan. 

The DAQ held three conference calls with the Charlotte Regional Transportation Planning 

Organization (CRTPO) - Rocky River Rural Planning Organization (RRRPO), GastonCleveland-Lincoln Metropolitan Planning Organization (GCLMPO), and Cabarrus Rowan 

Metropolitan Planning Organization (CRMPO) to determine what years to set MVEBs for the 

Charlotte maintenance plan. According to Section 93.118 of the transportation conformity rule, 

a maintenance plan must establish MVEBs for the last year of the maintenance plan (in this case, 

2026). The consensus formed during the interagency consultation process was that another 

MVEB should be set for the Charlotte maintenance plan base year of 2014. 

4.2 SAFETY MARGIN

As stated in Section 3.3.4, a safety margin is the difference between the attainment level of 

emissions from all source categories (i.e., point, area, on-road and nonroad) and the projected 

level of emissions from all source categories. The safety margins for the North Carolina portion 

of the Charlotte nonattainment area are listed in Table 3.12. The state may choose to allocate 

some of the safety margin to the MVEB, for transportation conformity purposes, so long as the 

total level of emissions from all source categories remains below the attainment level of 

emissions. 

The DAQ has decided to allocate a portion of the safety margin to the MVEB to allow for 

unanticipated growth in VMT, changes and uncertainty in vehicle mix assumptions, and 

uncertainty associated with mobile modeling that will influence the future year emission 

estimations. The DAQ has developed and implemented a five-step approach for determining a 

factor to use to calculate the amount of safety margin to apply to the MVEB for 2026 (see the 

following Section 4.3 and Appendix B.3). The percent increase to the MVEBs for the North 

Carolina counties in the Charlotte nonattainment area are listed in the Table 4.1. Note that 

because the initial MVEB year of 2014 is also the base year for the maintenance plan inventory, 

there is no safety margin and, therefore, no adjustments were made to the MVEB for 2014. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 44

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 4.1 Percent Increase to Mobile Vehicle Emissions Budget

County 2026

Cabarrus 20%

Gaston 20%

Iredell 22%

Lincoln 22%

Mecklenburg 17%

Rowan 20%

Union 20%

4.3 MOTOR VEHICLE EMISSION BUDGETS

Although the emissions up to this point have been expressed in terms of tons/day, for conformity 

purposes the MVEBs are expressed in kilograms/day (kg/day). Note that, for this reason, kg/day

was selected as the specified units for all MOVES2014 model outputs. Emissions values in 

kg/day were divided by 907.1847 to convert them to units of tons/day.

Table 4.2 shows the counties with their highway mobile NOx and VOC emissions, respectively, 

expressed in tons/day and the corresponding kg/day values for 2014 and 2026.

Table 4.2 Highway Mobile Source NOx and VOC Emissions in 2014 and 2026 for North 

Carolina Portion of the Charlotte Nonattainment Area

County

2014 NOx 2014 VOC 2026 NOx 2026 VOC

tons/day kg/day tons/day kg/day tons/day kg/day tons/day kg/day

Cabarrus* 6.60 5,989 4.15 3,765 1.86 1,685 2.04 1,854

Gaston* 8.14 7,389 4.66 4,228 1.98 1,793 1.73 1,571

Iredell* 3.36 3,045 1.95 1,768 0.93 841 0.82 742

Lincoln* 3.00 2,723 1.91 1,737 0.76 692 0.79 713

Mecklenburg 27.09 24,574 14.55 13,201 6.85 6,219 6.67 6,052

Rowan* 6.42 5,825 3.76 3,408 1.59 1,439 1.41 1,281

Union* 5.67 5,146 3.54 3,210 1.51 1,370 1.56 1,420

Total 60.28 54,691 34.52 31,317 15.48 14,039 15.02 13,633

* Emissions for portion of county included in nonattainment area.

As part of the consultation process on developing MVEBs, the DAQ coordinated three 

interagency conference calls with local and state transportation partners and the EPA’s Region 

IV staff to establish the framework and process for developing MVEBs. Based on these 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 45

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

conference calls, the participants in the consultation process unanimously agreed to the 

following:

Emissions Inventory and Forecast

 Use 2014 as the base year for the emissions inventory and include emissions estimates for 

2018, 2022, and 2026 (4-year increments) from the base year. 

 The Charlotte DOT runs the local transportation demand model based on inputs from the 

local transportation planning organizations to generate inputs (VMT, and speeds for daily 

travel periods, and human population to forecast VMT) needed to run MOVES2014 to 

estimate emissions for each year 

Geographic Extent of MVEBs

 Prepare separate MVEBs based on the latest MPO jurisdictional boundaries such that 

MVEBs are established for the CRMPO (Cabarrus and Rowan Counties), for the 

CRTPO-RRRPO (Iredell, Mecklenburg and Union Counties), and for the GCLMPO 

(Gaston and Lincoln Counties). Although Cleveland County is included in the 

GCLMPO, it is not included in the Charlotte ozone nonattainment area.

MVEB Years

 In addition to developing a MVEB for 2026 (required by EPA guidance), the group 

agreed to develop a MVEB for the base year 2014. 

Adjustment to MVEBs

 Allocate a portion of the safety margin to increase the MVEB for each county grouping 

following the process used to develop the MVEBs for the previous “Redesignation 

Demonstration and Maintenance Plan for the Charlotte-Gastonia-Rock Hill, NC-SC 1997 

8-Hour Ozone Nonattainment Area.” This process, which includes the following five 

steps, was used to adjust the MVEB for 2026. Because 2014 is the base year for the 

emissions inventory there is no safety margin; consequently, the MVEB for 2014 was not 

adjusted. 

Step 1 - Percentage below the standard

 All counties get 2% of their emissions allocated to MVEB in 2026

Step 2 - Account for unanticipated model input data changes

 All counties get an additional 5% of their emissions allocated to MVEB in 2026
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 46

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Step 3 - Provide flexibility and account for rapid growth for counties that are determined 

to be medium to small contributors to the on-road mobile NOx emissions inventory

 Counties with <8% of total on-road mobile source NOx emissions received an 

additional 5% of their emissions allocated to MVEB in 2026 (Iredell and Lincoln)

 Counties with 8% to 25% of total on-road mobile source NOx emissions received an 

additional 3% of their emissions allocated to MVEB in 2026 (Cabarrus, Gaston, 

Rowan and Union)

Step 4 - Account for input uncertainty in final year of the maintenance plan:

 All counties get 10% additional of their emissions allocated to MVEB in 2026 to 

account for potential changes in VMT, vehicle mix and vehicle age distribution

 Additional percentage is added to the current percentages outlined in the steps above

Step 5 - Ensure the sum of the safety margins applied to the MVEB does not exceed 50% 

of the total safety margin available. For 2026, Steps 1-4 accounted for:

 5% of the total NOx safety margin

 22% of the total VOC safety margin

Tables 4.3 through 4.5 provide the NOx and VOC MVEBs in kg/day, for transportation 

conformity purposes, for 2014 and 2026. Upon the EPA’s affirmative adequacy finding for these 

sub-area MVEBs, they will become the applicable MVEBs for transportation conformity.

Table 4.3 Cabarrus Rowan Metropolitan Planning Organization (CRMPO) 

MVEB in 2014 and 2026 (kg/day)*

2014 2026

NOx VOC NOx VOC

Base Emissions 11,814 7,173 3,124 3,135

Safety Margin Allocated to MVEB - - 625 627

Conformity MVEB 11,814 7,173 3,749 3,762

* Includes the portion of Cabarrus and Rowan Counties in the nonattainment area.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 47

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Table 4.4 Gaston-Cleveland-Lincoln Metropolitan Planning Organization (GCLMPO) 

MVEB in 2014 and 2026 (kg/day)*

2014 2026

NOx VOC NOx VOC

Base Emissions 10,079 5,916 2,485 2,284

Safety Margin Allocated to MVEB - - 511 471

Conformity MVEB 10,079 5,916 2,996 2,755

* Includes the portion of Gaston and Lincoln Counties in the nonattainment area. Although Cleveland 

County is included in the MPO it is not included in the Charlotte ozone nonattainment area.

Table 4.5 Charlotte Regional Transportation Planning Organization (CRTPO) -

Rocky River Rural Planning Organization (RRRPO) MVEB in 2014 and 

2026 (kg/day)*

2014 2026

NOx VOC NOx VOC

Base Emissions 32,679 18,038 8,430 8,214

Safety Margin Allocated to MVEB - - 1,516 1,476

Conformity MVEB 32,679 18,038 9,946 9,690

* Includes all of Mecklenburg County and the portion of Iredell and Union Counties in the nonattainment 

area.

New Safety Margins

A total of 2,650 kg/day (2.92 tons/day) of 2026 NOx safety margin were added to the MVEB for 

the Charlotte area. A total of 2,569 kg/day (2.83 tons/day) of 2026 VOC safety margin were 

added to the MVEB for the Charlotte area. The revised safety margins, which take into 

consideration the portion of the safety margin applied to the MVEB, for each projected year is 

listed below in Table 4.6.

Table 4.6 New Safety Margins for the North Carolina Portion of the 

Charlotte Nonattainment Area (tons/day)

Year NOx VOC

2014 N/A* N/A

2015 -6.00 -2.03

2018 -35.85 -8.71

2022 -43.51 -11.38

2026 -59.72 -9.82

* N/A = not applicable.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 48

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

5.0 STATE IMPLEMENTATION PLAN APPROVAL 

5.1 INTRODUCTION

For an area to be redesignated and have an approved maintenance plan, the SIP must include 

evidence of compliance with the rules relied on to show maintenance of the standard. This 

section provides the evidence of compliance with such rules for the Charlotte-Gastonia-Salisbury

2008 8-hour ozone nonattainment area.

5.2 EVIDENCE OF COMPLIANCE

Two counties in the Charlotte area (Gaston and Mecklenburg Counties) were designated as 

moderate nonattainment for 1-hour ozone effective January 1992. Since a redesignation 

demonstration and maintenance plan was submitted for this area prior to November 15, 1992, the 

CAA requirements for moderate areas were not required with the exception of the I/M program. 

An I/M program was established in the Charlotte area as prescribed by the 1990 CAA. 

Therefore, North Carolina has a fully approved SIP for this area. 

For the 1997 8-hour ozone standard, the DAQ submitted to the EPA for approval the Metrolina 

Attainment Demonstration SIP on June 15, 2007, and a Supplement to the Attainment 

Demonstration SIP on April 5, 2010. The North Carolina portion of the Metrolina nonattainment 

area includes the counties of Cabarrus, Gaston, Lincoln, Mecklenburg, Rowan and Union and 

Coddle Creek and Davidson Townships in Iredell County. The Reasonable Further Progress SIP 

was submitted to the EPA for approval on June 15, 2007 and a Revised Reasonable Further 

Progress SIP was submitted on November 30, 2009. The EPA approved the Revised Reasonable 

Further Progress SIP on October 12, 2012.

42

 On November 2, 2011 the DAQ submitted to the 

EPA a Redesignation Demonstration and Maintenance Plan for 1997 8-hour Ozone standard; and 

submitted a supplement to this SIP on March 28, 2013. The EPA approved the redesignation 

request and maintenance plan on December 2, 2013.43

For the 2008 8-hour ozone standard for the Charlotte nonattainment area, the DAQ submitted to 

the EPA for approval the Base Year (2011) Emissions Inventory and Emissions Statements SIP 

on July 7, 2014, to fulfill the requirements of Sections 182(a)(1) and 182(a)(3)(B) of the CAA.44 

 

42 77 FR 62159-62166.

43 78 FR 72036-72040.

44 http://ncair.org/planning/metrolina/metrolina_area_sip_plans.shtml.
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 49

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

Additionally, the following rules regulating emissions of VOCs and/or NOx in the Charlotte

nonattainment area counties have been approved, or have been submitted with a request to be 

approved, as part of the SIP:

15A NCAC 2D .0958, Work Practices For Sources of Volatile Organic Compounds,

15A NCAC 2D .0530, Prevention of Significant Deterioration,

15A NCAC 2D .0925, Petroleum Liquid Storage in Fixed Roof Tanks,

15A NCAC 2D .0926, Bulk Gasoline Plants,

15A NCAC 2D .0927, Bulk Gasoline Terminals,

15A NCAC 2D .0928, Gasoline Service Stations Stage I,

15A NCAC 2D .0932, Gasoline Truck Tanks and Vapor Collection Systems,

15A NCAC 2D .0933 Petroleum Liquid Storage in External Floating Roof Tanks

15A NCAC 2D .1000, Motor Vehicle Emission Control Standards.

15A NCAC 2D .1200, Control and Emissions from Incinerators

15A NCAC 2D .1409(b), Stationary Internal Combustion Engines

15A NCAC 2D .1416 - .1423, NOx SIP rules

15A NCAC 2D .1600, General Conformity

15A NCAC 2D .1700, Municipal Solid Waste Landfills, and

15A NCAC 2D .1900, Open Burning

15A NCAC 2D .2000, Transportation Conformity

15A NCAC 2D .2400 Clean Air Interstate Rules

Rules 15A NCAC 2D .0925, .0926, .0927, .0928, .0932, .0933, .0948, .0949, and .0958 have 

been approved as part of the SIP and are applicable across the state regardless of the size of the 

source.

Section 15A NCAC 2D .1000 also regulates emissions from motor vehicles in the North 

Carolina counties in and around the Charlotte nonattainment area and requires the use of the 

OBDII system, which provides an indication of NOx emissions as well as other pollutants.

Section 15A NCAC 2D .1200 regulates the controls and emissions from incinerators. Part of this 

rule has been submitted as part of the SIP, while .1205, .1206 and .1210 are part of the CAA 

Section 111(d) plans.

Two rules are conformity related, 15A NCAC 2D .1600 and .2000. General conformity related 

projects are covered under Section .1600, while transportation conformity related projects are 

covered under Section .2000. Although neither of these rules requires reduction in emissions, 

they do ensure that federal actions do not hinder attainment or maintenance of the NAAQS.

North Carolina has adopted an open burning rule, 15A NCAC 2D .1900 that prohibits open 

burning of vegetative material during Air Quality Action Days of Code Orange or higher in 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 50

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

forecasted areas of the state. Ozone forecasts are issued for the Charlotte area from May 1st

through September 30th, therefore this area is covered by this rule.

Section 15A NCAC 2D .2400 regulates nitrogen oxide emissions from electric generating units 

with a nameplate capacity of 25 megawatts or more producing electricity for sale. Section 15A 

NCAC 2D .2400 also covers industrial boilers that are covered under the NOx SIP rules. This 

Section replaces the NOx SIP rules beginning January 1, 2009. Although North Carolina did not 

rely on the emission reductions from CAIR for maintenance of the 2008 8-hour ozone standard, 

these regulations will result in additional reductions in NOx emissions regionally.

Another important set of rules that control volatile organic compound emissions in these counties 

is Section 15A NCAC 2D .1100, Control of Toxic Air Pollutants. These rules, however, have 

not been submitted to the EPA to be approved as part of the SIP.

There are two other rules that control emissions of volatile organic compounds in these areas. 

They are 15A NCAC 2D .0524, New Source Performance Standards, and 2D.1110, National 

Emission Standards for Hazardous Air Pollutants. Also, rule 2D.1111, Maximum Achievable 

Control Technology applies to control of emissions of volatile organic compounds. They are not 

part of the SIP, but the EPA has delegated the state enforcement authority for standards that have 

been adopted by the state. (The standards adopted by the state are state-enforceable regardless of 

the EPA delegation.)
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 51

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

6.0 STATE COMPLIANCE WITH CLEAN AIR ACT REQUIREMENTS 

Section 107(d)(3)(E)(v) of the CAA requires that the provisions of Section 110 (State 

Implementation Plans for the Primary and Secondary NAAQS) and Part D (Plan Requirements 

for Nonattainment Areas) of the CAA be met within the area to be redesignated. This means that 

North Carolina must meet all requirements, if any, that had come due as of the date of the 

redesignation request.

The EPA, in its latest guidance on redesignation requirements (as contained in a memorandum 

from John Calcagni, Director, Air Quality Management Division, Office of Air Quality Planning 

and Standards to the EPA Regional Offices dated September 4, 1992, see Appendix A), states 

that "For the purposes of redesignation, a state must meet all requirements of Section 110 and 

Part D that were applicable prior to submittal of the complete redesignation request. When 

evaluating a redesignation request, Regions should not consider whether the state has met 

requirements that come due under the Act after submittal of a complete redesignation request."

Monitoring is one of the requirements of Section 110. The DAQ commits to continue operating 

the current ozone monitors in the North Carolina portion of the Charlotte 2008 8-hour ozone 

nonattainment area, providing sufficient funding is available for continued operation. Any 

monitor shutdowns or relocations will only be made with the approval of EPA. No plans are 

underway to discontinue operation, relocation or otherwise affect the integrity of the ambient 

monitoring network in place. The current monitors are operated consistent with 40 CFR Part 58 

and any changes will only be made if they are consistent with 40 CFR Part 58.

For the 2008 8-hour ozone standard for the Charlotte marginal nonattainment area, the DAQ 

submitted to the EPA for approval the Base Year (2011) Emissions Inventory and Emissions 

Statements SIP on July 7, 2014, to fulfill the requirements of Part D, Sections 182(a)(1) and 

182(a)(3)(B) of the CAA.45 The DAQ believes that North Carolina has met all of the 

requirements of Section 110 and Part D. 

 

45 http://ncair.org/planning/metrolina/metrolina_area_sip_plans.shtml. 
Charlotte-Gastonia-Salisbury, NC 2008 8-hour Ozone Marginal 52

Nonattainment Area Redesignation Demonstration and Maintenance Plan April 16, 2015

7.0 CONCLUSION

The most recent three years of ozone monitoring data (2012-2014) for the Charlotte-GastoniaSalisbury nonattainment area demonstrate compliance with the NAAQS for 2008 8-hour ozone. 

Since the 1990’s, there have been many major programs enacted in North Carolina that have led 

to significant actual, enforceable emissions reductions, which have led to improvements in the 

air quality in the Charlotte area. Additionally, the maintenance plan demonstrates that the 

projected emissions inventories for 2026, the final year of the maintenance plan and 10 years 

beyond the expected redesignation year, as well as the interim years, are all less than the base 

year emissions inventory. In addition, the CAA Section 110(l) non-interference demonstration 

analysis indicates that increasing the RVP from 7.8 to 9.0 psi in Gaston and Mecklenburg 

Counties would not negatively impact the redesignation demonstration and maintenance plan for 

the Charlotte area. Therefore, maintenance of the 2008 8-hour ozone NAAQS has also been 

demonstrated.

This redesignation demonstration and maintenance plan has been prepared to meet the 

requirements of the 1990 CAA Amendments.