Redesignation Demonstration and Maintenance Plan 

for the 

Hickory (Catawba County) and 

Greensboro/Winston-Salem/High Point 

(Davidson and Guilford Counties) 

Fine Particulate Matter Nonattainment Areas 

Prepared by 

North Carolina Department of Environment and Natural Resources 

Division of Air Quality 

December 18, 2009 

Revised December 22, 2010 
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Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 i 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

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

Quality to request the Hickory and Greensboro/Winston-Salem/High Point fine particulate 

matter nonattainment areas be redesignated as attainment for the annual fine particulate matter 

national ambient air quality standard pursuant to §§107(d)(3)(D) and (E) of the Clean Air Act, as 

amended. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 ii 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

EXECUTIVE SUMMARY 

Introduction 

Fine particulate matter, also known as fine particles and PM2.5, refers to airborne particles less 

than or equal to 2.5 micrometers in diameter. Fine particles are treated as though they are a 

single pollutant, but they come from many different sources and are composed of many different 

compounds. PM2.5 exposure adversely affects human health, especially respiratory and 

cardiovascular systems. Individuals particularly sensitive to PM2.5 exposure include children, 

people with heart and lung disease, and older adults. 

A variety of meteorological and geographic factors influence the concentration levels of fine 

particles, including both the regional and local distribution of urbanized areas, primary and 

precursor emissions sources, and natural features such as oceans and forests. PM2.5

concentrations can also be high and exceed the national ambient air quality standards (NAAQSs) 

for fine particulate matter at any time of the year. Therefore, the United States Environmental 

Protection Agency (USEPA) mandates the year round monitoring of PM2.5 concentrations 

throughout the country. 

Nonattainment Designation 

The nonattainment designation was an action taken by the USEPA under Section 107(d) of the 

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

monitor is found to be in violation of a NAAQS. The USEPA took designation action in 2005 

based on the ambient data from 2001-2003. At that time, the design value for Hickory area 

(Catawba County) was 15.6 micrograms per cubic meter (μg/m3

) and the design value for the 

Greensboro/Winston-Salem/High Point area (Davidson and Guilford Counties, referred to as the 

Triad area) was 15.9 μg/m3. 

Current Air Quality 

The most recent three years of fine particulate monitoring data (2006-2008) for both the Hickory 

and Triad PM2.5 nonattainment areas demonstrate compliance with the annual fine particulate 

matter NAAQS. The three year design value at the Hickory monitor is 14.2 μg/m3. In the Triad 

nonattainment area, the three year design value at the Lexington monitor is 14.5 μg/m3 and the 

three year design value at the Mendenhall monitor is 12.9 μg/m3

. Additionally, the annual 

design values at all three sites are trending downward. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 iii 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Maintenance Plan Requirements 

The State of North Carolina has implemented permanent and enforceable reductions in sulfur 

dioxide (SO2) and nitrogen oxide (NOx) emissions, which are precursors to fine particulates. 

These actions include implementing the on-board diagnostic vehicle inspection and maintenance 

program that began on July 1, 2002, and an open burning ban during air quality action days. In 

addition, there have been several State rules that have resulted in reductions in emissions within 

and surrounding the nonattainment area. These State actions include the NOx State 

Implementation Plan (SIP) Call, the Clean Smokestacks Act legislation, and heavy-duty engine 

stop-gap rule for model years 2005 and 2006. Finally, several actions at the Federal level by the 

USEPA have resulted in lower emissions throughout the eastern portion of the country. These 

Federal actions include the Tier 2 engine standards for light and medium duty vehicles, heavyduty engine standards, the low sulfur gasoline and diesel requirements, and off-road engine 

standards. 

This combination of State and Federal actions has resulted in cleaner air in the PM2.5

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

result in continued maintenance of the 1997 annual PM2.5 NAAQS in this region. A baseline 

year emissions inventory for NOx, SO2, and direct PM2.5 was developed for 2008, since the 

design value for the 2006-2008 period showed attainment of the 1997 annual PM2.5 NAAQS. 

Future year emissions inventories were also developed for the interim years 2011, 2014, 2017, 

and a final year emission inventory was developed for 2021. The future year emissions were 

lower than the 2008 emissions in all cases. This demonstrates that the PM2.5 nonattainment areas 

are expected to maintain the 1997 annual PM2.5 NAAQS through 2021, since in no future year 

are the emissions expected to be greater than they were in the baseline year. The areas are also 

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

Conclusion and Request for Redesignation 

Based on the information above and criteria established in Section 107(d)(3)(E) of the CAA, 

North Carolina is requesting that the USEPA redesignate the Hickory and Greensboro/WinstonSalem/High Point fine particulate matter nonattainment areas to attainment. The monitoring data 

clearly shows that the region has attained the annual fine particulate matter 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 control measures 

listed above. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 iv 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

TABLE OF CONTENTS 

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

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

1.1 WHAT IS FINE PARTICULATE MATTER? ................................................................. 1-1

1.2 CLEAN AIR ACT OF 1990 .............................................................................................. 1-2

1.3 AIR QUALITY HISTORY ............................................................................................... 1-2

1.4 CLEAN AIR ACT REDESIGNATION CRITERIA ........................................................ 1-3

2.0 AIR QUALITY ...................................................................................................................... 2-1

2.1 HISTORIC AIR QUALITY (1999 – 2007) ...................................................................... 2-1

2.2 RECENT AIR QUALITY VALUES (2006 –2008) ......................................................... 2-3

2.3 PERMANENT AND ENFORCEABLE EMISSIONS REDUCTIONS ........................... 2-4

3.0 MAINTENANCE PLAN ....................................................................................................... 3-1

3.1 CONCEPT OF NORTH CAROLINA'S MAINTENANCE PLAN ................................. 3-1

3.2 FOUNDATION CONTROL PROGRAM ........................................................................ 3-2

3.2.1 Federal Control Measures .......................................................................................... 3-2

3.2.2 State Control Measures .............................................................................................. 3-5

3.2.3 Additional Programs Supporting Maintenance .......................................................... 3-9

3.3 EMISSIONS INVENTORIES AND MAINTENANCE DEMONSTRATION ............. 3-10

3.3.1 Theory of Approach ................................................................................................. 3-10

3.3.2 Emission Inventories ................................................................................................ 3-11

3.3.3 Summary of Emissions ............................................................................................ 3-15

3.3.4 Maintenance Demonstration .................................................................................... 3-16

3.4 CONTINGENCY PLAN ................................................................................................. 3-17

3.4.1 Overview .................................................................................................................. 3-17

3.4.2 Primary and Secondary Triggers ............................................................................. 3-18

3.4.3 Action Resulting From Trigger Activation .............................................................. 3-19

3.4.4 Tracking Program for Ongoing Maintenance .......................................................... 3-20

4.0 MOTOR VEHICLE EMISSIONS BUDGET FOR CONFORMITY ................................... 4-1

4.1 TRANSPORTATION CONFORMITY ............................................................................ 4-1

4.2 POLLUTANTS TO BE CONSIDERED ........................................................................... 4-1

4.2.1 Precursor Pollutants NOx, VOC, and Ammonia ........................................................ 4-2

4.2.2 Reentrained Road Dust .............................................................................................. 4-2

4.2.3 Precursor Pollutant SO2 ............................................................................................. 4-3

4.2.4 Direct PM2.5 Emissions .............................................................................................. 4-5

4.3 SAFETY MARGIN ........................................................................................................... 4-7

4.4 MOTOR VEHICLE EMISSION BUDGETS ................................................................... 4-7
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 v 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

4.5 NEW SAFETY MARGINS ............................................................................................ 4-10

5.0 STATE IMPLEMENTATION PLAN APPROVAL ............................................................. 5-1

5.1 INTRODUCTION ............................................................................................................. 5-1

5.2 EVIDENCE OF COMPLIANCE ...................................................................................... 5-1

6.0 STATE COMPLIANCE WITH CLEAN AIR ACT REQUIREMENTS.............................. 6-1

7.0 CONCLUSION ...................................................................................................................... 7-1
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 vi 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

LIST OF APPENDICES 

APPENDIX A: CORRESPONDENCE AND GUIDANCE DOCUMENTS 

APPENDIX B: STAKEHOLDER CORRESPONDENCE REGARDING MOTOR VEHICLE 

EMISSION BUDGETS 

APPENDIX C.1: POINT SOURCE EMISSION INVENTORY DOCUMENTATION 

APPENDIX C.2: AREA SOURCE EMISSION INVENTORY DOCUMENTATION 

APPENDIX C.3: ON-ROAD MOBILE SOURCE EMISSION INVENTORY 

DOCUMENTATION 

APPENDIX C.4: NONROAD MOBILE SOURCE EMISSION INVENTORY 

DOCUMENTATION 

APPENDIX D: MENDENHALL DATA REPLACEMENT DOCUMENTATION 

APPENDIX E: PUBLIC NOTICE REPORT, COMMENTS RECEIVED AND RESPONSES 

LIST OF TABLES 

Table 2-1 Historic PM2.5 Annual Averages (1999-2007) ............................................................ 2-2

Table 2-2 Historic PM2.5 Design Values (2000 – 2007) .............................................................. 2-3

Table 2-3 Current PM2.5 Data (2006 -2008) ................................................................................ 2-4

Table 2-4. Annual Emissions from NC Sources in USEPA Acid Rain Database ....................... 2-7

Table 2-5. Annual SO2 Emissions for Utilities Near the PM2.5 Nonattainment areas (tons/year) 2-9

Table 3-1 OBDII Phase-in Effective Dates ................................................................................. 3-6

Table 3-2 I/M NOx Benefits by County ....................................................................................... 3-6

Table 3-3 Estimated Emission Reductions from Open Burning Regulation ............................... 3-8

Table 3-4. Point Source NOx Emissions (tons per year) ............................................................ 3-11

Table 3-5 Point Source SO2 Emissions (tons per year) ............................................................. 3-12

Table 3-6. Point Source PM2.5 Emissions (tons per year) .......................................................... 3-12

Table 3-7. Area Source NOx Emissions (tons per year) ............................................................ 3-12

Table 3-8. Area Source SO2 Emissions (tons per year) ............................................................. 3-13

Table 3-9. Area Source PM2.5 Emissions (tons per year) .......................................................... 3-13

Table 3-10. On-road Mobile Source NOx Emissions (tons per year) ........................................ 3-13

Table 3-11. On-road Mobile Source SO2 Emissions (tons per year) ......................................... 3-14

Table 3-12. On-road Mobile Source PM2.5 Emissions (tons per year) ...................................... 3-14

Table 3-13. Nonroad Mobile Source NOx Emissions (tons per year) ........................................ 3-14

Table 3-14. Nonroad Mobile Source SO2 Emissions (tons per year) ........................................ 3-15
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 vii 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Table 3-15. Nonroad Mobile Source PM2.5 Emissions (tons per year) ...................................... 3-15

Table 3-16. Total Man-Made NOx Emissions (tons per year) ................................................... 3-15

Table 3-17. Total Man-Made SO2 Emissions (tons per year) .................................................... 3-15

Table 3-18. Total Man-Made PM2.5 Emissions (tons per year) ................................................. 3-16

Table 3-19 Maintenance Demonstration for Hickory PM2.5 Nonattainment Area ................... 3-16

Table 3-20 Maintenance Demonstration for Triad PM2.5 Nonattainment Area ........................ 3-16

Table 3-21 Safety Margin for Hickory PM2.5 Nonattainment Area .......................................... 3-17

Table 3-22 Safety Margin for Triad PM2.5 Nonattainment Area ............................................... 3-17

Table 4-1. On-Road Mobile Source PM2.5 Emissions ................................................................ 4-8

Table 4-2. On-Road Mobile Source NOx Emissions .................................................................. 4-9

Table 4-3 Catawba County MVEB ............................................................................................. 4-9

Table 4-4 Davidson County MVEB ........................................................................................... 4-9

Table 4-5 Guilford County MVEB ........................................................................................... 4-10

Table 4-6 New Safety Margins for the Hickory PM2.5 nonattainment area .............................. 4-10

Table 4-7 New Safety Margins for the Triad PM2.5 nonattainment area .................................. 4-11

LIST OF FIGURES 

Figure 1-1. USEPA Designated Annual PM2.5 Nonattainment Areas in North Carolina ........... 1-3

Figure 2-1. PM2.5 Monitor Locations in the PM2.5 Nonattainment Areas................................... 2-1

Figure 2-3. Location of Power Plants in the Vicinity of the PM2.5 Nonattainment Areas .......... 2-8

Figure 3-1. North Carolina’s Inspection & Maintenance (I/M) Phase-In Map .......................... 3-5

Figure 4-1. Speciated Data for the Hickory area (left) and the Triad area (right) ....................... 4-3

Figure 4-2. North Carolina’s 2009 Statewide SO2 Emissions .................................................... 4-4

Figure 4-3. Hickory Area 2009 Primary PM2.5 Emissions ........................................................... 4-6
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 viii 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

LIST OF ACRONYMS 

Acronym Definition 

oF Degrees Fahrenheit 

CAA Clean Air Act 

CAAA Clean Air Act Amendments of 1990 

CERR Consolidated Emissions Reporting Rule 

CFR Code of Federal Regulations 

CO Carbon Monoxide 

E-GAS 5.0 Economic Growth Analysis System version 5.0 

FR Federal Register 

FRM Federal Reference Method 

GUAMPO Greensboro Urban Area Metropolitan Planning Organization 

HC Hydrocarbons 

I/M Inspection and Maintenance 

MVEB Motor Vehicle Emission Budget 

NAAQS National Ambient Air Quality Standard 

NCCSA North Carolina Clean Smokestacks Act 

NCDAQ North Carolina Division of Air Quality 

NCDENR North Carolina Department of Natural Resources 

NCDOT North Carolina Department of Transportation 

NOx Nitrogen Oxides 

PM Particulate Matter 

PM2.5 Fine Particulate Matter 

ppm Parts per million 

QA Quality Assure 

SAFETY-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for 

Users 

SIP State Implementation Plan 

SO2 Sulfur Dioxide 

SOx Sulfur Oxides 

SUV Sports Utility Vehicle 

TIP Transportation Improvement Program 

TPD Tons per Day 

TSP Total Suspended Particulates 

USEPA U.S. Environmental Protection Agency 

VMT Vehicle Miles Traveled 

VOC Volatile Organic Compounds 

μg/m3

 Micrograms per cubic meter 

μm Micrometer 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 1-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

1.0 INTRODUCTION 

1.1 WHAT IS FINE PARTICULATE MATTER? 

Fine particulate matter, also known as fine particles and PM2.5, refers to airborne particles less 

than or equal to 2.5 micrometers (μm) in diameter. Fine particles are treated as though they are a 

single pollutant, but they come from many different sources and are composed of many different 

compounds. PM2.5 exposure adversely affects human health, especially respiratory and 

cardiovascular systems. Individuals particularly sensitive to PM2.5 exposure include children, 

people with heart and lung disease, and older adults. 

PM2.5 can be liquid, solid, or can have a solid core surrounded by liquid. PM2.5 can include 

material produced by combustion, photochemical reactions, and can contain salt from sea spray 

and soil-like particles. Particles are distinguished based on the method of formation. Primary 

particles are particles directly emitted into the atmosphere and retain the same chemical 

composition as when they were released. Secondary particles are those formed through chemical 

reactions involving atmospheric oxygen, water vapor, hydroxyl radical, nitrates, sulfur dioxide 

(SO2), oxides of nitrogen (NOx), and organic gases from natural and anthropogenic sources. 

PM2.5 can therefore be composed of varying amounts of different species, including: 

• Sulfates 

• Nitrates (usually found in the form of ammonium nitrate) 

• Ammonium 

• Hydrogen ion 

• Particle bound water 

• Elemental carbon 

• Organic compounds 

o Primary organic species (from cooking and combustion) 

o Secondary organic compounds 

• Crustal material (includes calcium, aluminum, silicon, magnesium, and iron) 

• Sea salt (generally only found at coastal monitoring sites) 

• Transitional metals 

• Potassium (generally from wood burning or cooking) 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 1-2 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

The most significant sources of PM2.5 and its precursors are coal-fired power plants, industrial 

boilers and other combustion sources. These emissions are often transported over large 

distances. Other sources of PM2.5 emissions include mobile sources, area sources, fires, 

windblown dust, and biogenic, i.e., naturally occurring emissions such as sea salt from oceans 

and organics from trees. 

A variety of meteorological and geographic factors influence the concentration levels of fine 

particles, including both the regional and local distribution of urbanized areas, primary and 

precursor emissions sources, and natural features such as oceans and forests. PM2.5

concentrations can also be high and exceed the national ambient air quality standards (NAAQSs) 

for fine particulate matter at any time of the year. Therefore, the United States Environmental 

Protection Agency (USEPA) mandates in the Code of Federal Regulations (CFR) the year round 

monitoring of PM2.5 concentrations throughout the country (40 CFR 58.App. D, 4.7). 

In 1997, the USEPA promulgated the primary (health) and secondary (welfare) NAAQSs for 

PM2.5 (40 CFR 50.7), setting the standard at a 15.0 micrograms per cubic meter (μg/m3) annual 

average and at a 65 μg/m3 daily or 24-hour average. A violation of the annual PM2.5 NAAQS 

occurs when the annual average PM2.5 concentration averaged over a three consecutive year 

period is equal to or greater than 15.1 μg/m3. A violation of the daily PM2.5 NAAQS occurs 

when the annual 98th percentile of daily PM2.5 concentration averaged over a three consecutive 

year period is equal to or greater than 66 μg/m3. The annual or daily PM2.5 design value for a 

nonattainment area is the highest design value for any monitor in that 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 (CAAA). With the implementation of the PM2.5 standard, areas could be 

designated under Section 172 of the CAAA (subpart 1) and have five years from designation to 

attain the standard. 

1.3 AIR QUALITY HISTORY 

On January 5, 2005, the USEPA designated the Hickory area (Catawba County) and the 

Greensboro/Winston-Salem/High Point area (referred to as the Triad area and consisting of 

Davidson and Guilford Counties) as “subpart 1” nonattainment for the annual PM2.5 standard 

based on the ambient data from 2001-2003 (Figure 1-1). At that time, the design values for the 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 1-3 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Hickory and Triad nonattainment areas were 15.6 μg/m3 and 15.9 μg/m3, respectively. The 

official designation and classification was published in the Federal Register (FR) on 

January 5, 2005 (70 FR 944) and became effective on April 5, 2005. Prior to the implementation 

of the new PM2.5 standard, these areas had been in attainment of the coarse particulate matter 

(PM10) and total suspended particulate matter (TSP) standards. All areas of North Carolina met 

the 1997 daily PM2.5 standard. 

Figure 1-1. USEPA Designated Annual PM2.5 Nonattainment Areas in North Carolina 

All violating monitors were attaining the annual PM2.5 standard with the inclusion of the 2008 

ambient data. The 2006-2008 design values for the Hickory and Triad nonattainment areas are 

14.2 μg/m3 and 14.5 μg/m3, respectively. Both areas continue to attain the daily PM2.5 standard. 

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 USEPA has determined that the NAAQS have been attained. For fine particulate 

matter, the areas must show that the average of the annual average values from three (3) 

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

15.0 μg/m3

 or lower. 

2. The applicable implementation plan has been fully approved by the USEPA under section 

110(k). 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 1-4 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

3. The USEPA 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 USEPA has fully approved a maintenance plan, including a contingency plan, for the 

areas under section 175A. 

In the sections to follow, the North Carolina Department of Environment and Natural Resources, 

Division of Air Quality (NCDAQ) will provide the technical data necessary to show that both the 

Hickory and Triad nonattainment areas have attained and are expected to maintain the annual 

fine particulate matter standard, and have met the requirements for redesignation set forth above. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

2.0 AIR QUALITY 

2.1 HISTORIC AIR QUALITY (1999 – 2007) 

The NCDAQ has collected ambient monitoring data for Catawba, Davidson, and Guilford 

Counties since 1999. At the time of fine particulate matter designations, there were three Federal 

Reference Method (FRM) monitors for fine particulate matter in the three counties; Hickory, 

Lexington, and Mendenhall (Figure 2-1). In late 2007, another PM2.5 FRM monitor was installed 

in Guilford County, located in Colfax which is located just west of Greensboro. These monitors 

were installed in accordance with the 40 CFR 58. 

Figure 2-1. PM2.5 Monitor Locations in the PM2.5 Nonattainment Areas 

Data from the fourth quarter of 2006 at Mendenhall is incomplete due to construction at the 

monitoring site and complications in relocating the site. The NCDAQ had to move the site since 

the school where the monitoring site is located constructed a two-story field house immediately 

adjacent to the monitoring site (letter to USEPA Region 4, Appendix D). The school had not 

notified the NCDAQ of its intention to build the field house. During a routine site visit, the 

NCDAQ discovered that construction had started within four meters of the monitoring site. At 

that point, the monitor no longer met the ambient monitoring siting criteria and had to be shut 

down and moved. 

A new site was promptly found and appropriate permits were applied for. It took the NCDAQ 

four months (instead of an estimated 3 weeks) to resolve all the necessary permits and complete 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-2 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

the relocation of the monitor. This unfortunate circumstance resulted in most of the fourth 

quarter to go unmonitored. 

The USEPA guidance does not address missing monitoring data for an entire quarter. The 

NCDAQ decided the best option was to develop regressive analysis between Mendenhall and 

surrounding monitors. Data from surrounding monitors was incorporated into the regressive 

analysis to obtain a best estimate for the fourth quarter at Mendenhall. Please see Appendix D 

for more details. 

The Mendenhall monitor has never violated the PM2.5 standards and has consistently had annual 

averages that were 1 – 2 μg/m3

 below the annual PM2.5 NAAQS. The NCDAQ is confident that 

had the monitor been operating during the 2006 fourth quarter, the ambient air quality levels 

would have been consistent with the estimated values the NCDAQ has developed. The USEPA 

has also proposed to determine that the Greensboro/Winston-Salem/High Point nonattainment 

area has attained the 1997 PM2.5 NAAQS (74 FR 51249). 

Tables 2-1 and 2-2 below show the air quality data and corresponding design values, 

respectively, for the monitors in the both the Hickory and Triad nonattainment areas from 1999 

to 2006. Table 2-2 indicates that the Hickory and Lexington monitors were in violation of the 

PM2.5 NAAQS for this period, while the Mendenhall monitor was consistently below the annual 

PM2.5 standard. 

Table 2-1 Historic PM2.5 Annual Averages (1999-2007) 

Monitor Fine Particulate Matter Annual Average (μg/m3

) 

1999 2000 2001 2002 2003 2004 2005 2006 2007 

Hickory Nonattainment Area 

Hickory 

AIRS ID #37-035-0004 

Catawba County 

17.42 17.63 15.98 15.36 15.04 15.00 15.95 15.17 14.54 

Triad Nonattainment Area 

Lexington 

AIRS ID #37-057-0002 

Davidson County 

17.34 18.04 16.45 15.88 15.17 15.18 15.40 15.13 14.64 

Mendenhall 

AIRS ID #37-081-0013 

Guilford County 

 13.72 13.32 13.97 14.01 14.06* 13.05 

*Estimated fourth quarter data 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-3 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Table 2-2 Historic PM2.5 Design Values (2000 – 2007) 

Monitor Design Value (μg/m3

) 

99-01 00-02 01-03 02-04 03-05 04-06 05-07 

Hickory Nonattainment Area 

Hickory 

AIRS ID #37-035-0004 

Catawba County 

17.0 16.3 15.5 15.1 15.3 15.4 15.2 

Triad Nonattainment Area 

Lexington 

AIRS ID #37-057-0002 

Davidson County 

17.3 16.8 15.8 15.4 15.3 15.2 15.1 

Mendenhall 

AIRS ID #37-081-0013 

Guilford County 

 13.7 13.8 14.0* 13.7* 

 Note: Bolded values represent violations of the annual fine particulate matter standard. 

*Estimated fourth quarter 2006 data used in Design Value calculation. 

2.2 RECENT AIR QUALITY VALUES (2006 –2008) 

The most recent three years of PM2.5 monitoring data (2006-2008) for both the Hickory and 

Triad nonattainment areas demonstrate compliance with the annual fine particulate matter 

NAAQS. Table 2-3 is a summary of the annual averages for the monitors located in the 

nonattainment areas for 2006-2008 and their respective design values. The Colfax monitor only 

has data for 2008 and therefore does not have sufficient data to calculate a design value. 

However, the 2008 annual average is significantly below the annual PM2.5 standard. Therefore, 

the NCDAQ is confident the area is in compliance of the NAAQS. The 2008 PM2.5 monitoring 

data for both the Hickory and the Triad areas have been fully quality assured and were officially 

submitted to the USEPA on May 9, 2009. 

As noted in the previous section, the fourth quarter data for 2006 at the Mendenhall monitoring 

site is incomplete. After an extensive analysis, the NCDAQ is confident that the Mendenhall 

monitor is not in violation of the PM2.5 NAAQS (see Appendix D). It should be noted that the 

Mendenhall monitor has never violated the annual PM2.5 NAAQS in the history of its operation. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-4 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Table 2-3 Current PM2.5 Data (2006 -2008) 

Monitor Year PM2.5 Annual Average 

(μg/m3

) 

Design Value (μg/m3

)

2006-2008 

Hickory Nonattainment Area 

Hickory 

AIRS ID #37-035-0004 

Catawba County 

2006 15.17 

2007 14.54 14.2 

2008 12.85 

Triad Nonattainment Area 

Lexington 

AIRS ID #37-057-0002 

Davidson County 

2006 15.13 

2007 14.64 14.5 

2008 13.66 

Mendenhall 

AIRS ID #37-081-0013 

Guilford County 

2006 14.06* 

2007 13.05 12.9* 

2008 11.45 

Colfax 

AIRS ID #37-081-0141 

Guilford County 

2006 N/A 

2007 N/A N/A 

2008 12.21 

*Estimated fourth quarter 2006 data used in Design Value calculation. 

2.3 PERMANENT AND ENFORCEABLE EMISSIONS REDUCTIONS 

There are several State and Federal measures that have been enacted in recent years that are 

resulting in permanent emissions reductions. Most of these emission reductions are due to 

regulations and thus are enforceable. However, a few measures are non-regulatory but will still 

result in emission reductions. A list of those measures that contributed to the permanent 

emission reductions are listed below and are more fully described in Section 3.2. 

The federal measures that have been implemented include: 

• Tier 2 vehicle standards: In addition to NOx controls, the Tier 2 rule also reduced the 

sulfur content of gasoline to 30 parts per million (ppm) starting in January of 2006. 

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

about 300 ppm. These emission reductions are federally enforceable. 

• Heavy-duty gasoline and diesel highway vehicle standards: Second phase of 

standards and testing procedures, which began in 2007, will reduce particulate matter 

from heavy-duty highway engines, and will also reduce highway diesel fuel sulfur 

content to 15 ppm since the sulfur damages emission control devices. The total 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-5 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

• program is expected to achieve a 90% reduction in particulate matter (PM) emissions. 

These emission reductions are federally enforceable. 

• Nonroad spark-ignition engines and recreational engines standards: Tier 1 of this 

standard was implemented in 2004 and Tier 2 started in 2007, and will reduce 

particulate matter emissions. These emission reductions are federally enforceable. 

• Large nonroad diesel engine standards: Promulgated in 2004, this rule is being 

phased in between 2008 and 2014. This rule will also reduce sulfur content in 

nonroad diesel fuel. When fully implemented, this rule will reduce NOx and direct 

PM2.5 emissions by over 90%. These emission reductions are federally enforceable. 

The state measures that have been implemented include: 

• Clean Air Bill: This State legislation expanded the inspection and maintenance (I/M) 

program from 9 counties to 48. It was phased-in in the Hickory and Triad 

nonattainment areas from July 1, 2002 through July 1, 2003. This program will 

reduce NOx and Volatile Organic Compound (VOCs), and Carbon Monoxide (CO). 

These emission reductions are state enforceable. 

• Open burning: This regulation prohibits the burning of man-made materials 

throughout the State. Additionally, this regulation prohibits open burning of yard 

waste in areas that the NCDAQ forecasts an air quality action day. The open burning 

regulation will reduce fine particulate matter emissions, as well as NOx, VOCs and 

CO emissions. These emission reductions are state enforceable. 

• Heavy duty diesel engine gap filling rule: This rule requires engine manufacturers to 

perform the supplemental testing requirements for heavy duty diesel engines for 

model years 2005 and 2006 due to delays in the USEPA’s rule and will reduce PM 

emissions. These emission reductions are state enforceable. 

• Clean Smokestack Act: This rule requires coal-fired power plants to reduce annual 

NOx emissions by 77% by 2009 and to reduce annual sulfur dioxide emissions by 

49% by 2009 and 73% by 2013. This legislation sets a cap on NOx and SO2

emissions, which the public utilities cannot meet by purchasing emission credits. 

These emission reductions are state enforceable.
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-6 

Errata to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

• NOx State Implementation Plan (SIP) Call rule: This rule was predicted to reduce 

summertime NOx emissions from power plants and other industries by 68%. These 

emission reductions are state and federally enforceable. 

• Diesel Retrofits: As part of the North Carolina Mobile Source Emission Reduction 

Grants program, a number of cities, counties and school districts have installed Diesel 

Oxidation Catalysts (DOCs) or Diesel Particulate Filters (DPFs) on their diesel 

equipment. The vehicles that have been retrofitted include schools buses, as well as 

county fleet trucks for solid waste pickup. These types of filters are designed to 

remove particulate matter, and when used with ultra low sulfur diesel fuel, NOx and 

VOC emissions are also reduced. Even though these emission reductions are 

voluntary and not enforceable, they are still considered permanent reductions. 

• Diesel Emissions Reduction Act (DERA): DERA provides new diesel emissions 

reduction grant authority for the USEPA. This funding is used to achieve significant 

reductions in diesel emissions that improve air quality and protect public health. The 

DERA funds that the NCDAQ have received have been used to retrofit, repower, or 

replace existing diesel engines from on-road and nonroad mobile source 

vehicles/equipment. This program will reduce PM, NOx, and VOC emissions. Even 

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

considered permanent reductions. 

One of the largest components of PM2.5 in the southeastern United States is sulfate. This is 

formed through various chemical reactions from the precursor SO2. Another component of 

PM2.5 is nitrate, which is formed from the precursor NOx. Controls installed on coal-fired power 

plants over the past few years have significantly reduced these two precursor pollutants. 

Table 2-4 presents the annual emissions for the North Carolina sources that are in the USEPA’s 

Clean Air Markets database. Since 2002, when the NOx controls started coming on-line to meet 

the NOx SIP Call and later to meet the North Carolina Clean Smokestacks Act (NCCSA), the 

NOx emissions from subject sources have decreased over 84,000 tons per year. To meet the SO2

emission caps in the NCCSA, the North Carolina public utilities started installing SO2 controls 

late in 2005. Since then, the SO2 emissions from the utilities in North Carolina have decreased 

nearly 274,000 tons. The decline in SO2 emissions has coincided with the decline in annual 

PM2.5 concentrations across North Carolina. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-7 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Table 2-4. Annual Emissions from NC Sources in USEPA Acid Rain Database 

Year Annual SO2 Emissions 

(Tons) 

Annual NOx Emissions 

(Tons) 

2002 462,993 145,706 

2003 462,041 135,879 

2004 472,320 124,079 

2005 500,936 114,300 

2006 462,143 108,584 

2007 370,827 64,770 

2008* 227,030 61,669 

*Data from 2008 is considered preliminary. 

As mentioned in Section 1.1, PM2.5 is composed of many species from varying sources. 

Figure 2-2 presents the North Carolina statewide averaged PM2.5 speciation data from the 

speciation trends network (STN) monitors for the year 2004. The figure presents sulfates and 

organic carbons as the main contributors to PM2.5, each with 29% of the total PM2.5 mass. The 

“other” portion of the PM2.5 that accounts for 17% of the mass can be attributed to water, sea 

salts, and other trace materials captured with the STN monitors. 

Figure 2-2. North Carolina PM2.5 Speciation for 2004 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-8 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Organic carbon is predominately attributed to biogenic emission sources and sulfate is associated 

with SO2 emissions. When evaluated across North Carolina and also throughout both 

nonattainment areas and surrounding regions, the SO2 is primarily from the point source sector. 

For this reason, reductions in SO2 emissions will provide the greatest reductions in PM2.5

ambient concentrations. Figure 2-3 displays the location of the major power plants located near 

the PM2.5 nonattainment areas. Table 2-5 presents the SO2 emissions from these nine power 

plants as reported from the USEPA acid rain database. It is clearly demonstrated that the annual 

emissions from these facilities have significantly decreased since 2005, with over 250,000 tons 

of SO2 emission reduction in the 2008 compared to 2005. This is over a 50% reduction in utility 

SO2 emissions that are permanent and enforceable. These reductions have taken place beginning 

in 2006, which includes the first year of the attaining 3-year design value. Since the final 

compliance date for the NCCSA SO2 emissions caps is 2013, future design values are expected 

to continue to decline below the 2006-2008 attaining design values. 

Figure 2-3. Location of Power Plants in the Vicinity of the PM2.5 Nonattainment Areas 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 2-9 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Table 2-5. Annual SO2 Emissions for Utilities Near the PM2.5 Nonattainment areas (tons/year) 

Facility County 2005 2006 2007 2008 

Belews Creek Rockingham 96,813 95,290 86,388 17,252 

Buck Rowan 9,582 9,560 10,261 7,353 

Cliffside Rutherford 28,209 29,128 27,566 29,421 

Dan River Stokes 4,248 7,068 7,672 6,687 

Allen Gaston 45,424 45,395 50,550 49,578 

Marshall Catawba 100,540 85,050 24,754 6,174 

Mayo Person 27,076 24,499 22,811 20,072 

Riverbend Gaston 13,964 15,148 15,907 15,942 

Roxboro Person 101,444 94,627 65,247 24,436 

Total 427,301 405,765 311,155 176,914 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

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 annual fine 

particulate matter in the Hickory and Greensboro/Winston-Salem/High Point nonattainment 

areas 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 cleaner 

engine programs, and low sulfur gasoline and low sulfur diesel fuel programs. Additionally, 

although the federal Clean Air Interstate Rule (CAIR) has been remanded back to the USEPA, a 

replacement rule is expected to be promulgated in 2011. This new rule is expected to be as 

stringent as CAIR. 

The NCDAQ has implemented programs that will remain enforceable and are hereby submitted 

as the plan to ensure that maintenance of the annual fine particulate matter standard will 

continue. Sources are prohibited from reducing emission controls (anti-backsliding) following 

the redesignation of the area unless such a change is first approved by the USEPA as a revision 

to the North Carolina SIP that is consistent with Section 110(l) of the Clean Air Act. 

For the maintenance demonstration, the base year of 2008 was chosen since it is a year that falls 

within the attaining design value period of 2006-2008 and some emissions inventory data was 

already developed for this year. The interim years chosen were: 2011, 2014, and 2017 since the 

USEPA recommends three-year increments for interim years. The final year of the maintenance 

demonstration is 2021, since the CAA requires maintenance for at least ten years after 

redesignation. The maintenance demonstration consists of a comparison between the 2008 

baseline emissions inventory and the projected emissions inventories (for 2011, 2014, 2017, and 

2021), which consider economic and population growth as well as expected controls. The 

comparison shows that the total emissions in each of the interim years and the final year will be 

lower than in the base year, which demonstrates maintenance of the annual PM2.5 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 

quality standard for annual PM2.5. The secondary trigger will be a monitored air quality pattern 

that suggests an actual annual PM2.5 NAAQS violation may be imminent, such as repeated 

exceedances of the daily fine particulate matter standard. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-2 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

3.2 FOUNDATION CONTROL PROGRAM 

The main element of the maintenance plan is the foundation control program. The foundation 

control program contains the controls 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 State's foundation control program is 

essential in demonstrating maintenance of the air quality standards. 

The foundation control program consists of Federal and State measures. The Federal measures 

include the cleaner fuel programs and the federal highway motor vehicle and off-road equipment 

control program and controls on power plants. State measures include the I/M program, the NOx

SIP Call rule, the NCCSA, and open burning and idle reduction regulations. The state measures 

also include additional programs that support maintenance of the PM2.5 standard. Most of these 

emission reductions are due to regulations and thus are enforceable. However, a few measures 

are non-regulatory but will still result in emission reductions. 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 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 grams of NOx per mile. 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 new 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. These emission reductions are 

federally enforceable. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-3 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Heavy-Duty Gasoline and Diesel Highway Vehicles Standards

The USEPA standards designed to reduce NOx and VOC emissions from heavy-duty gasoline 

and diesel highway vehicles began to take effect in 2004. The second phase of the standards and 

testing procedures began in 2007 and will reduce particulate matter from heavy-duty highway 

engines, and reduces 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 in NOx emissions for the 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 USEPA 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 reduce the allowable sulfur in nonroad diesel fuel by over 

99%. Prior to the fuel standard change, nonroad diesel fuel averaged about 3,400 ppm sulfur. 

The rule limits nonroad diesel sulfur content to 500 ppm by 2006 and 15 ppm by 2010. The 

combined engine and fuel rules is expected to reduce NOx and PM emissions from large nonroad 

diesel engines by over 90%, compared to current nonroad engines using higher-content sulfur 

diesel. 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 (HC) 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 

engines over 37 kilowatts are used in yachts, cruisers, and other types of pleasure craft. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-4 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

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 all of the nonroad spark-ignition and recreational engine standards are fully implemented, 

an overall 72% reduction in HC, 80% reduction in NOx, and 56% reduction in CO emissions are 

expected by 2020. These controls will help reduce ambient concentrations of ozone, CO, and 

PM2.5. These emission reductions are federally enforceable. 

NOx SIP Call in Surrounding States

In October 1998, the USEPA made a finding of significant contribution of NOx emissions from 

certain states and published a rule that set ozone season (May to September) NOx budgets for the 

purpose of reducing regional transport of ozone (63 FR 57356). This rule, referred to as the NOx

SIP Call, required ozone season controls to be put on utility and industrial boilers, as well as 

internal combustion engines, in 22 states in the Eastern United States. A NOx emissions budget 

was set for each state and the states were required to develop rules that would assure that each 

state met its budget. A NOx trading program was established, allowing sources to buy credits to 

meet their NOx budget as opposed to actually installing controls. The emission budgets were to 

be met by the beginning of 2004. Even with the trading program, the amount of ozone season 

NOx emissions has decreased significantly in and around North Carolina. These emission 

reductions are federally enforceable. 

Clean Air Interstate Rule

On May 12, 2005, the USEPA promulgated the “Rule To Reduce Interstate Transport of Fine 

Particulate Matter and Ozone (Clean Air Interstate Rule); Revisions to Acid Rain Program; 

Revisions to the NOx SIP Call”, referred to as CAIR. This rule established the requirement for 

States to adopt rules limiting the emissions of NOx and SO2 and a model rule for the states to use 

in developing their rules. The purpose of the CAIR is to reduce interstate transport of precursors 

of fine particulate and ozone. 

This rule provides annual state caps for NOx and SO2 for large fossil-fuel-fired electric 

generating units in two phases, with the Phase I caps for NOx and SO2 starting in 2009 and 2010, 

respectively. Phase II caps become effective in 2015. The USEPA is allowing the caps to be 

met through a cap and trade program if a state so chooses to participate in the program. These 

emission reductions are federally enforceable. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-5 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Due to court challenges of CAIR in 2008, the USEPA will be making changes to the program by 

2011. However, the existing CAIR rules will remain in place until the USEPA promulgates 

changes to the program. Additionally, the revisions to the CAIR program are expected to be as 

stringent as the existing program. 

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. 

Clean Air Bill

The 1999 Clean Air Bill expanded the vehicle emissions I/M program in North Carolina from 9 

counties to 48 counties, between July 1, 2002 through January 1, 2006 (Figure 3-1). Vehicles are 

tested using the onboard diagnostic system (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 PM2.5 nonattainment area are listed below. 

Figure 3-1. North Carolina’s Inspection & Maintenance (I/M) Phase-In Map 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-6 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 3-1 OBDII Phase-in Effective Dates 

County Date 

Catawba July 1, 2003 

Davidson July 1, 2003 

Guildford July 1, 2002 

 

These emission reductions are state enforceable. The expected NOx benefits for the maintenance 

years are listed in Table 3-2 below. 

Table 3-2 I/M NOx Benefits by County 

NOx I/M Benefit (Tons/year) 2008 2011 2014 2017 2021 

Catawba County 171 136 132 122 111 

Davidson County 180 166 139 129 114 

Guilford County 541 505 403 358 318 

NOx SIP Call Rule/CAIR

In response to the USEPA’s NOx SIP call, North Carolina adopted rules to control the emissions 

of NOx from large stationary combustion sources. These rules cover (1) fossil fuel-fired 

stationary boilers, combustion turbines, and combined cycle systems serving a generator with a 

nameplate capacity greater than 25 MW and selling any amount of electricity, (2) fossil fuelfired stationary boilers, combustion turbines, and combined cycle systems having a maximum 

design heat input greater than 250 million British thermal units per hour, and (3) reciprocating 

stationary internal combustion engines rated at equal to or greater than 2400 brake horsepower 

(3000 brake horsepower for diesel engines and 4400 brake horsepower for dual fuel engines). 

As part of the NOx SIP Call, the USEPA rules established a NOx budget for sources in North 

Carolina and other states. North Carolina has a Phase II budget (i.e., emission allowance) of 

165,022 tons NOx per ozone season. 

Besides amending existing NOx rules and adopting new NOx rules specifically to address the 

USEPA NOx SIP Call, the North Carolina rules also require new sources to control emissions of 

NOx. The objective of this requirement is (1) to aid in meeting the NOx budget for North 

Carolina for minor sources and (2) to aid in attaining and maintaining the ambient air quality 

standard for ozone in North Carolina. North Carolina’s NOx SIP Call rule was predicted to 

reduce summertime NOx emissions from power plants and other industries by 68% by 2006. In 

October 2000, the North Carolina Environmental Management Commission (EMC) adopted 

rules requiring the reductions. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-7 

Errata to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

In 2009, the NOx SIP Call program was replaced with the CAIR, a cap-and-trade program that 

will achieve reductions of emissions of SO2 and NOx in the eastern United States. NOx sources 

that were regulated under the NOx SIP Call are now regulated under the CAIR program. North 

Carolina adopted the CAIR rules in 2006 (amended in 2008). North Carolina’s CAIR rules set 

annual SO2 allowances as well as both ozone season and annual NOx allowances for coal-fired 

electric generating units and other large combustion sources. These regulations are due to a 

Federal program and thus are both State and Federally enforceable. 

Due to the Court challenges of CAIR in 2008, the USEPA will be making changes to this 

program soon. However, the existing CAIR rules will remain in place until the USEPA 

promulgates changes to the program. 

Clean Smokestacks Act

In June 2002, the North Carolina General Assembly enacted the NCCSA, which requires coalfired power plants in North Carolina to reduce annual NOx emissions by 77% by 2009. These 

power plants must also reduce annual SO2 emissions by 49% by 2009 and 73% by 2013. It is 

significant to note that this law sets a cap on NOx and SO2 emissions for the State which the 

North Carolina public utilities cannot meet by purchasing credits from sources outside of North 

Carolina. With requiring year-round NOx controls and not allowing the purchase of NOx credits 

to meet the caps, the NCCSA reduces NOx emissions beyond the requirements of the NOx SIP 

Call Rule. One of the first state laws of its kind in the nation, this legislation provides a model 

for other states in controlling multiple air pollutants from older coal-fired power plants. These 

emissions reductions are state enforceable. 

Prevention of Significant Deterioration 

All new major sources of SO2 and NOx will be evaluated under the prevention of significant 

deterioration program and are required to use best available control technology. These emissions 

reductions are state enforceable. 

Open Burning

The North Carolina open burning regulation prohibits the burning of man-made materials 

statewide. In June 2004, the EMC approved revisions to the open burning regulation banning 

open burning of yard waste and land clearing debris on forecasted Code Orange or higher "air 

quality action days," for those counties that the NCDAQ or local air programs forecast ozone or 

fine particulate matter. The following counties in the Hickory area are subject to this rule: 

Alexander, Catawba, southeastern Burke and southeastern Caldwell. The following counties in
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-8 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

the Triad area are subject to this rule: Alamance, Caswell, Davidson, Davie, Forsyth, Guilford, 

Randolph, Rockingham and Stokes. 

The open burning regulation reduces PM, NOx, SO2, VOC, and CO emissions and are state 

enforceable. The estimated emission reductions through the attainment and maintenance period 

are presented in Table 3-3. For a full explanation of how these emission reductions were 

estimated, please refer to Appendix C.2, the Area Source Emissions Inventory Documentation. 

Table 3-3 Estimated Emission Reductions from Open Burning Regulation 

Pollutant/County 2008 2011 2014 2017 2021 

NOx Emissions (tons/year) 

Hickory Area 

Catawba 56 66 76 85 100

 

Triad Area 

Davidson 94 109 126 141 167

Guilford 79 91 105 119 140

Triad Total 173 200 231 260 307

SO2 Emissions (tons/year) 

Hickory Area 

Catawba 10 11 12 14 17

 

Triad Area 

Davidson 16 18 21 23 28

Guilford 13 15 17 20 23

Triad Total 29 33 38 43 51

PM2.5 Emissions (tons/year) 

Hickory Area 

Catawba 326 380 438 493 581

 

Triad Area 

Davidson 541 632 729 819 965

Guilford 454 530 612 688 809

Triad Total 995 1162 1341 1507 1774

Idle Reduction Regulation

The EMC adopted the Heavy-Duty Vehicle Idling Restrictions rule to reduce unnecessary idling 

of heavy-duty trucks on July 9, 2009. This rule has received several letters of objection and will 

undergo a legislative review in the Spring of 2010 before becoming effective. Once in effect, 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-9 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

this rule will be state enforceable and generally prevent 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. The expected emissions from this regulation were not 

included in the mobile source emissions estimated for this maintenance plan because of the 

uncertainty of the regulations. 

3.2.3 Additional Programs Supporting Maintenance 

Air Awareness Program

The North Carolina Air Awareness Program is a public outreach and education program of the 

NCDAQ. 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 air quality 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 year round daily air quality 

forecast. The NCDAQ produces a daily fine particulate matter forecasts and corresponding air 

quality index for the Hickory forecast area, while the Forsyth County Environmental Affairs 

Department provides daily fine particulate matter forecasts and the corresponding air quality 

index for the Triad region. 

Transportation Conformity 

The NCDAQ works closely with the North Carolina Department of Transportation (NCDOT) 

and local transportation agencies to assure that Transportation Improvement Programs (TIPs) in 

the nonattainment areas are consistent with and conform to the State's air quality program, 

including the SIP, and meet the Federal requirements on transportation conformity. This 

conformity review is performed for all federally funded and all other major projects contained in 

TIPs, regardless of source of funding. Technical analysis of transportation plans, programs, and 

projects for conformity are done cooperatively by the Statewide Planning Branch of the NCDOT 

and the NCDAQ. In the event that the NCDAQ disagrees with the NCDOT on a conformity 

determination or other conformity related issue, the NCDAQ and the NCDOT will present the 

issue to the Governor for resolution. 

The public and interested parties are given an early and reasonable opportunity to comment on 

transportation plans, programs, projects and proposed conformity determinations in accordance 

with procedures adopted by metropolitan planning organizations pursuant to the requirements of 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-10 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

SAFETY-LU (the Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy 

for Users) as well as any updated transportation legislation and the CAA as amended. 

Mobile Source Emission Reduction Grants

• Diesel Retrofits: As part of the North Carolina Mobile Source Emission Reduction 

Grants program, a number of cities, counties and school districts have installed Diesel 

Oxidation Catalysts (DOCs) or Diesel Particulate Filters (DPFs) on their diesel 

equipment. The vehicles that have been retrofitted include schools buses, as well as 

county fleet trucks for solid waste pickup. Although these types of filters are 

designed to remove fine particulate matter, when used with ultra low sulfur diesel 

fuel, NOx and VOC emissions are also reduced. 

• Diesel Emissions Reduction Act (DERA): DERA provides new diesel emissions 

reduction grant authority for the USEPA. This funding is used to achieve significant 

reductions in diesel emissions that improve air quality and protect public health. In 

response to DERA, the USEPA created grant and funding programs under the 

National Clean Diesel Campaign to build on the success of its regulatory and 

voluntary efforts to reduce emissions from diesel engines. The DERA funds that the 

NCDAQ have received have been used to retrofit, repower, or replace existing diesel 

engines from on-road and nonroad mobile source vehicles/equipment. 

3.3 EMISSIONS INVENTORIES AND MAINTENANCE DEMONSTRATION 

3.3.1 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 NCDAQ is the comparison of emissions inventories for the years 2008 and 2021. 

For the maintenance demonstration, the base year of 2008 was chosen since it is a year that falls 

within the attaining design value period of 2006-2008 and some emissions inventory data was in 

the process of being developed for this year. The maintenance demonstration is made by 

comparing the 2008 baseline emissions inventory to the 2021 projected emissions inventory. 

The baseline emissions inventory represents an emission level for a period when the ambient air 

quality standard was not violated, 2006-2008. 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 shoul
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-11 

Errata to the Redesignation Demonstration and Maintenance Plan December 22, 2010 

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 2008 baseline to demonstrate that these years are also expected to 

show continued maintenance of the annual fine particulate matter standard. 

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

mobile and nonroad mobile. The projected emissions inventories have been estimated using 

projected rates of growth in population, traffic, economic activity, expected control programs, 

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. 

3.3.2 Emission Inventories 

There are four different man-made emission inventory source classifications: (1) stationary point, 

(2) area, (3) on-road mobile and (4) nonroad mobile sources. 

Point sources are those stationary sources that require an Air Permit to operate. In general, these 

sources have a potential to emit more than 5 tons per year of CO, NOx, PM, SO2 and/or VOC 

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 

USEPA’s AP-42. There are usually several emission sources for each facility. Emission data is 

collected for each point source at a facility and the data is entered into an in-house database 

system. For the projected year's inventory, point sources are adjusted by growth factors based on 

Standard Industrial Classification codes. The growth factors are generated using the USEPA’s 

Economic Growth Analysis System version 5.0 (E-GAS 5.0) program or using growth patterns 

obtained from County Business Patterns. For detailed discussion on how the point sources 

emission inventory was developed, see Appendix C.1. A summary of the point source emissions 

are presented in Tables 3-4 to 3-6. 

Table 3-4. Point Source NOx Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 13,310 10,549 10,548 10,548 10,548 

Davidson 841 865 892 920 961 

Guilford 231 231 232 233 237 

Triad Total 1,072 1,096 1,124 1,153 1,198 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-12 

Errata to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 3-5 Point Source SO2 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 6,189 6,187 6,186 6,184 6,183 

Davidson 286 289 292 295 299 

Guilford 449 451 453 455 458 

Triad Total 735 740 745 750 757 

Table 3-6. Point Source PM2.5 Emissions (tons per year) 

County 2008 2011 2014 2017 2021 

Catawba 6,976 6,975 6,975 6,973 6,971 

Davidson 179 178 177 176 175 

Guilford 62 62 62 63 63 

Triad Total 241 240 239 239 238 

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 projected 

year's inventory, area source emissions are changed by population growth, projected production 

growth, or when applicable, by E-GAS 5.0 growth factors. For detailed discussion on how the 

area source emission inventory was developed, see Appendix C.2. A summary of the area source 

emissions are presented in Tables 3-7 to 3-9. 

Table 3-7. Area Source NOx Emissions (tons per year) 

County 2008 2011 2014 2017 2021 

Catawba 662 614 566 520 454 

Davidson 583 551 516 486 438 

Guilford 1,243 1,210 1,177 1,146 1,099 

Triad Total 1,826 1,816 1,693 1,632 1,537 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-13 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 3-8. Area Source SO2 Emissions (tons per year) 

County 2008 2011 2014 2017 2021 

Catawba 2,263 2,037 1,808 1,580 1,277 

Davidson 983 838 692 548 353 

Guilford 4,129 3,905 3,683 3,460 3,164 

Triad Total 5,112 4,743 4,375 4,008 3,517 

Table 3-9. Area Source PM2.5 Emissions (tons per year) 

County 2008 2011 2014 2017 2021 

Catawba 682 658 629 606 559 

Davidson 1,071 1,028 979 937 857 

Guilford 697 663 623 590 524 

Triad Total 1,768 1,691 1,602 1,527 1,381 

For mobile sources, the USEPA’s Motor Vehicle Emission Simulator (MOVES) mobile model is 

run to generate emissions. The MOVES model includes the road class vehicle miles traveled 

(VMT) as an input file and can directly output the estimated emissions. For the projected years’ 

inventories, the on-road 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 C.3. A 

summary of the on-road mobile source emissions are presented in Tables 3-10 to 3-12. 

Table 3-10. On-road Mobile Source NOx Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 4,982 4,005 3,240 2,591 2,054 

Davidson 5,267 4,095 3,227 2,536 1,974 

Guilford 14,499 11,157 8,882 7,143 5,796 

Triad Total 19,766 15,252 12,109 9,679 7,770 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-14 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 3-11. On-road Mobile Source SO2 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 35 20 18 19 20 

Davidson 36 19 17 18 18 

Guilford 111 62 55 59 63 

Triad Total 147 81 72 77 81 

Table 3-12. On-road Mobile Source PM2.5 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 166 127 107 89 73 

Davidson 169 121 97 77 60 

Guilford 465 330 272 221 183 

Triad Total 634 451 369 298 243 

Nonroad mobile sources are equipment that can move but do not use the roadways, i.e., lawn 

mowers, construction equipment, railroad locomotives, aircraft, etc. The emissions from this 

category are calculated using the USEPA’s NONROAD2008a nonroad mobile model, with the 

exception of the railroad locomotives and aircraft engine. The railroad locomotive and aircraft 

engine emissions are estimated by taking activity data, such as landings and takeoffs, and 

multiply by an emission factor. These emissions are also estimated at the county level. For the 

projected years’ inventories, the emissions are estimated using the USEPA’s NONROAD2008a 

nonroad mobile model, E-GAS 5.0 growth factors or projected landing and takeoff data for 

aircraft. For detailed discussion on how the nonroad mobile emission inventory was developed, 

see Appendix C.4. A summary of the nonroad mobile source emissions are presented in 

Tables 3-13 to 3-15. 

Table 3-13. Nonroad Mobile Source NOx Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 1,173 922 700 551 453 

Davidson 1,831 1,632 1,467 1,275 1,115 

Guilford 3,864 3,371 2,816 2,350 1,980 

Triad Total 5,695 5,003 4,283 3,625 3,095 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-15 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 3-14. Nonroad Mobile Source SO2 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 18 6 4 3 4 

Davidson 25 17 2 2 2 

Guilford 96 51 42 42 43 

Triad Total 121 68 44 44 45 

Table 3-15. Nonroad Mobile Source PM2.5 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 70 67 57 46 38 

Davidson 71 67 58 46 40 

Guilford 264 252 220 186 157 

Triad Total 335 319 278 232 197 

3.3.3 Summary of Emissions 

The sum total of these man-made emissions for the PM2.5 nonattainment areas is tabulated in 

Tables 3-16 though 3-18. 

Table 3-16. Total Man-Made NOx Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 20,127 16,090 15,054 14,210 13,509 

Davidson 8,522 7,143 6,102 5,217 4,488 

Guilford 19,837 15,969 13,107 10,872 9,112 

Triad Total 28,359 23,112 19,209 16,089 13,600 

Table 3-17. Total Man-Made SO2 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 8,505 8,250 8,016 7,786 7,484 

Davidson 1,330 1,163 1,003 863 672 

Guilford 4,785 4,469 4,233 4,016 3,728 

Triad Total 6,115 5,632 5,236 4,879 4,400 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-16 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 3-18. Total Man-Made PM2.5 Emissions (tons per year)

County 2008 2011 2014 2017 2021 

Catawba 7,894 7,827 7,768 7,714 7,641 

Davidson 1,490 1,394 1,311 1,236 1,132 

Guilford 1,488 1,307 1,177 1,060 927 

Triad Total 2,978 2,701 2,488 2,296 2,059 

3.3.4 Maintenance Demonstration 

As discussed above, maintenance is demonstrated when the future years total man-made 

emissions are less than the 2008 baseline emissions. The following tables summarized the SO2, 

NOx, and primary PM2.5 emissions for both the Hickory and Triad nonattainment areas. The 

difference between the base year and the final year of the plan illustrates that the continued 

maintenance of the annual fine particulate matter NAAQS is expected. 

Table 3-19 Maintenance Demonstration for Hickory PM2.5 Nonattainment Area 

Year NOx 

(tons per year) 

SO2 

(tons per year) 

PM2.5 

(tons per year) 

2008 20,127 8,505 7,894 

2011 16,090 8,250 7,827 

2014 15,054 8,016 7,768 

2017 14,210 7,786 7,714 

2021 13,509 7,484 7,641 

Difference from 

2008 to 2021 -6,618 -1,021 - 253 

Table 3-20 Maintenance Demonstration for Triad PM2.5 Nonattainment Area 

Year NOx

(tons per year) 

SO2

(tons per year) 

PM2.5

(tons per year) 

2008 28,359 6,115 2,978 

2011 23,112 5,632 2,701 

2014 19,209 5,236 2,488 

2017 16,089 4,879 2,296 

2021 13,600 4,400 2,059 

Difference from 

2008 to 2021 -14,759 -1,715 - 919 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-17 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

The difference between the attainment level of emissions (2008) from all man-made sources and 

the projected level of emissions from all man-made sources in the nonattainment areas are 

considered the “safety margin”. The safety margin for each projected year is listed below in 

Table 3-21 and 3-22. 

Table 3-21 Safety Margin for Hickory PM2.5 Nonattainment Area 

Year NOx

(tons per year) 

SO2

(tons per year) 

PM2.5

(tons per year) 

2011 -4,037 -255 -67 

2014 -5,073 -489 -126 

2017 -5,917 -719 -180 

2021 -6,618 -1,021 -253 

Table 3-22 Safety Margin for Triad PM2.5 Nonattainment Area 

Year NOx

(tons per year) 

SO2

(tons per year) 

PM2.5

(tons per year) 

2011 -5,247 -483 -277 

2014 -9,150 -879 -490 

2017 -12,270 -1,236 -682 

2021 -14,759 -1,715 -919 

For both nonattainment areas, there are significant safety margins from 2011 to 2021. In 

addition to the above safety margins within the PM2.5 nonattainment areas, SO2 emissions from 

nearby coal-fired power plants will be significantly reduced due to the NCCSA. This effectively 

gives the PM2.5 nonattainment areas an even larger safety margin for SO2. Table 2-5 shows the 

SO2 reductions at nearby coal-fired power plants. These reductions will benefit both the Triad 

and Hickory nonattainment areas and will provide large safety margins through 2021. 

3.4 CONTINGENCY PLAN 

3.4.1 Overview 

The two main elements of the North Carolina contingency plan are tracking and triggering 

mechanisms to determine when contingency 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 annual 

PM2.5 NAAQS at any of the monitors in either PM2.5 nonattainment area. The secondary trigger 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-18 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

will be a rolling 12 quarter average that exceeds the annual PM2.5 NAAQS. The tertiary trigger 

will be a monitored annual average that exceeds the annual PM2.5 NAAQS. Upon either the 

primary or secondary triggers being activated, the NCDAQ will commence analyses to 

determine what additional measures, if any, will be necessary to attain or maintain the annual 

PM2.5 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 Federal Consolidated Emissions Reporting Rule 

(CERR) and Air Emissions Reporting Rule (AERR) to the projected inventory, and to the 

attainment year inventory contained in this maintenance plan. The CERR and AERR reporting 

years coincide with the baseline, interim and final years of the emission inventory in this 

maintenance demonstration. 

3.4.2 Primary and Secondary Triggers 

The primary trigger of the contingency plan will be a violation of the annual PM2.5 standard, or 

when the three-year average of the average annual ambient concentration is greater than 

15.0 μg/m3 at any monitor in the PM2.5 nonattainment areas. The trigger date will be 60 days 

from the date that the State observes an annual average concentration that, when averaged with 

the two previous annual average PM2.5 concentrations, would result in a three-year average 

greater than 15.0 μg/m3. 

The secondary trigger will apply where no actual violation of the annual PM2.5 standard has 

occurred, but where the State finds that the rolling 12-quarter average monitored PM2.5 levels 

exceed the PM2.5 NAAQS. A pattern will be deemed to exist when the average PM2.5 

concentrations of any 12 consecutive quarters is greater than 15.0 μg/m3 at any monitor within 

the PM2.5 nonattainment areas. The trigger date will be 60 days from the date that the State 

observes a rolling 12-quarter average greater than 15.0 μg/m3

 at any monitor. 

Similarly, the tertiary trigger will not be an actual violation of the annual PM2.5 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 either of the PM2.5 nonattainment areas has an annual average 

greater than 15.0 μg/m3

, 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 an annual average greater 

than 15.0 μg/m3 at any monitor. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-19 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

3.4.3 Action Resulting From Trigger Activation 

There are a number of programs that are still being implemented in North Carolina that will 

continue to reduce fine particulate matter and its precursors. The NCCSA has a final compliance 

year of 2013 by which the public utilities in North Carolina must meet their SO2 emissions caps. 

It is estimated that an additional 133,320 tons of SO2 will be reduced from the 2008 emission 

levels for the sources subject to the NCCSA. Additionally, the NCDAQ is still awarding grants 

for retrofits, replacement or repowering of diesel engines for on-road and nonroad mobile 

sources. Since it is possible that the speciation composition of fine particulate matter may 

change in the future years, it is important that the NCDAQ identify the pollutant or pollutants for 

which further reductions are needed in order to maintain the annual PM2.5 NAAQS. 

Once the primary or secondary trigger is activated, the Planning Section of the NCDAQ shall 

commence analyses including trajectory analyses of high PM2.5 days, and emissions inventory 

assessment to determine those emission control measures that will be required for attaining or 

maintaining the annual PM2.5 standard. Additionally, the PM2.5 speciation data from the STN 

monitors will be reviewed to determine which species are the more predominant components for 

the period where a violation or exceedance of the NAAQS was observed. 

If it is determined that the cause of the violation or exceedance of the PM2.5 NAAQS is due to 

sources outside of North Carolina, then the NCDAQ will commence discussion with regulatory 

authorities responsible for upwind sources to determine additional actions to be implemented. 

The State of North Carolina has already filed a Section 126 petition in order to ensure that 

neighboring states reduce their utility emissions in a timely manner. As a result of the recent 

court decision in the State of North Carolina vs. Tennessee Valley Authority, additional 

emissions reductions are anticipated for upwind TVA sources. 

If it is determined that the violation or exceedance occurred due to sources within North 

Carolina, then by November 1 of the year following the year 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 annual PM2.5 NAAQS. If the 

rules are still needed, then rules would become State effective by the following July 1, unless 

legislative review is required. Each adopted rule will include a schedule that will require 

compliance with the rule no later than 2 years after adoption of the rule. 

The measures that will be considered for adoption upon a trigger of the contingency plan 

include: Reasonably Available Control Technology on stationary sources in the PM2.5

nonattainment area counties, diesel inspection and maintenance program, implementation of 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 3-20 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

diesel retrofit programs, including incentives for performing retrofits, and additional controls in 

upwind areas. 

Once the tertiary trigger is activated, the Planning Section of the NCDAQ shall commence 

analyses including meteorological evaluation, trajectory analyses of high PM2.5 days, and 

emissions inventory assessment to understand why an annual exceedance of the standard has 

occurred. Once the analyses are completed, the NCDAQ will work with the local air awareness 

program and develop an outreach plan to identify any additional voluntary measures that can be 

implemented. NCDAQ will work with the local air awareness coordinator to implement the plan 

for the following summer. 

3.4.4 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 

NCDAQ. The NCDAQ will commit to review these emissions inventories to determine if an 

unexpected growth in NOx, SO2 or primary particulate matter emissions in the PM2.5

nonattainment areas may endanger the maintenance of the annual PM2.5 standard. Additionally, 

as new VMT data is provided by the North Carolina Department of Transportation (NCDOT), 

the NCDAQ commits to review this data and determine if any unexpected growth in VMT may 

endanger the maintenance of the annual PM2.5 standard. 

Additionally, under the CERR and AERR the NCDAQ is required to develop a comprehensive, 

annual, statewide emissions inventory every three years and is due twelve to eighteen months 

after the completion of the inventory year. The CERR and AERR inventory years coincide with 

the baseline, interim and final years of the maintenance plan. Therefore, the NCDAQ commits 

to compare these inventories as they are developed with the maintenance plan to determine if 

additional steps are necessary for continued maintenance of the annual PM2.5 standard in this 

area. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

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 annual fine particulate matter standard. This means that the level of emissions 

estimated by the NCDOT or the metropolitan planning organizations for the TIP and Long 

Range Transportation Plan must not exceed the motor vehicle emission budgets (MVEBs) as 

defined in this maintenance plan. 

4.2 POLLUTANTS TO BE CONSIDERED 

40 CFR 93.119(f)(7) through (10) identifies the pollutants for PM2.5 that regional emissions 

analysis needs to be performed for transportation conformity purposes. These parts of the rule 

are listed below: 

§119(f)(7) – PM2.5 in PM2.5 areas; 

§119(f)(8) – Reentrained road dust in PM2.5 areas only if the EPA [Environmental 

Protection Agency] Regional Administrator or the director of the State air agency 

has made a finding that emissions from reentrained road dust within the area are 

a significant contributor to the PM2.5 nonattainment problem and has so notified 

the MPO and DOT [Department of Transportation]; 

§119(f)(9) – NOx [nitrogen oxides] in PM2.5 areas, unless the EPA Regional 

Administrator and the director of the State air agency have made a finding that 

emissions of NOx from within the area are not a significant contributor to the 

PM2.5 nonattainment problem and has so notified the MPO and DOT; and 

§119(f)(10) – VOC, SO2 and/or ammonia in PM2.5 areas if the EPA Regional 

Administrator or the director of the State air agency has made a finding that any 

of such precursor emissions from within the area are a significant contributor to 

the PM2.5 nonattainment problem and has so notified the MPO and DOT. 

Only primary, or direct PM2.5, tailpipe emissions must be considered for transportation 

conformity regional emissions analysis. The other precursor pollutants and reentrained road dust 

only need to be considered if the State air agency and/or the USEPA have deemed the pollutant 

as a significant contributor to the PM2.5 nonattainment problem. The following sections discuss 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-2 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

the significance of the precursor pollutants and reentrained road dust to the PM2.5 nonattainment 

problem. 

4.2.1 Precursor Pollutants NOx, VOC, and Ammonia 

The PM2.5 precursor NOx is presumed to be a significant contributor to the PM2.5 nonattainment 

problem by the USEPA. The NCDAQ has determined that NOx is a relatively minor contributor 

to the PM2.5 concentrations in North Carolina. However, the NCDAQ is not asserting that NOx

is an insignificant precursor for the 1997 PM2.5 standard. Therefore, the NCDAQ will establish 

county level MVEBs for NOx for all three PM2.5 nonattainment counties. 

For the purpose of this attainment demonstration, VOC and ammonia are presumed to be 

insignificant contributors to the PM2.5 nonattainment problem by the USEPA. The NCDAQ 

agrees with the USEPA that both VOC and ammonia are insignificant contributors to the PM2.5

nonattainment problem in North Carolina. Since these precursors have been deemed 

insignificant, no MVEBs are being established for VOC or ammonia. 

An affirmative insignificance finding from the USEPA only relieves the transportation partners 

from a regional emissions analysis for PM2.5 emissions for these areas and does not relieve them 

of the other transportation conformity requirements. The transportation partners will need to 

note the VOC and Ammonia insignificance finding (if found adequate and approved by the 

USEPA) in future conformity determinations. 

4.2.2 Reentrained Road Dust 

The majority of the roads in North Carolina are paved so there is minimum road dust due to the 

paved roads. The factor to calculate reentrained road dust on paved roads is very small. What 

dust is generated, has been shown in the literature, Methodology to Estimate the Transportable 

Fraction (TF) of Fugitive Dust Emissions for Regional and Urban Scale Air Quality Analyses, 

US EPA, August 3, 2005, to be inconsequential. 

This fact is affirmed by the small crustal component in the PM2.5 speciated data which measures 

only 3% at Hickory monitoring site (Catawba County) in 2002 and only 2% at Lexington 

monitoring site (Davidson County) in 2004 (see Figure 4-1 below). 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-3 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Figure 4-1. Speciated Data for the Hickory area (left) and the Triad area (right) 

Since the reentrained road dust is not a significant contributor to the PM2.5 nonattainment 

problem, the NCDAQ will not be establishing MVEBs for this source category. An affirmative 

insignificance finding from the USEPA only relieves the transportation partners from a regional 

emissions analysis for reentrained road dust emissions for these areas and does not relieve them 

of the other transportation conformity requirements. The transportation partners will need to 

note the reentrained road dust insignificance finding (if found adequate and approved by the 

USEPA) in future conformity determinations. 

4.2.3 Precursor Pollutant SO2

The PM2.5 precursor SO2 could not be deemed insignificant to the PM2.5 nonattainment problem. 

However, the NCDAQ has determined that SO2 emitted by the mobile source sector is 

insignificant. The USEPA in its Federal Register notice for PM2.5 does not address the mobile 

sector in its listing of significant emissions. North Carolina agrees with the following statements 

addressing SO2 from on-road mobile emissions as published in the May 6, 2005, Federal 

Register, (70 FR 24283): 

“While speciated air quality data show that sulfate is a relatively significant component 

(e.g., ranging from nine to 40 percent) of PM2.5 mass in all regions of the country, 

emissions inventory data and projections show that on-road emissions of SOx constitute a 

‘‘de minimis’’ (i.e., extremely small) portion of total SOx emissions. Emissions inventory 

data for 1999 for the 372 potential PM2.5 nonattainment counties for PM2.5 (based on 

Hickory

AIRS Code 370350004 POC 5 (ROUTINE)

Date(s): 1/2/2002 - 12/4/2002

Average Concentration (μg/m3)

Nitrate

6%

Sulfate

30%

Ammonium

10%

Organic carbon

32%

Elemental carbon

4%

Crustal component

3%

Other

15%

(NC) - Lexington

AIRS Code 370570002 POC 5 (ROUTINE)

Date(s): 1/16/2004 - 2/9/2005

Average Concentration (μg/m3)

Nitrate

7%

Sulfate

29%

Ammonium

10%

Organic carbon

28%

Elemental carbon

4%

Crustal component

2%

Other

20%
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-4 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

1999–2001 air quality data) show that on-road sources were responsible for only two 

percent of total SOx emissions. 

Furthermore, EPA has already adopted two regulations that will greatly reduce 

emissions of SOx from on-road sources by the time such regulations are both in full effect 

in 2009. First, in 2004 the low sulfur gasoline program began to be phased in and will be 

fully effective in 2007 (February 10, 2000, 65 FR 6697). This regulation will reduce the 

sulfur content of gasoline by approximately 90 percent when fully effective. Second, in 

2006 the low sulfur diesel program will begin to be phased in and will be fully effective 

by 2009 (January 18, 2001, 66 FR 5001). This regulation will reduce the sulfur content of 

diesel fuel by approximately 97 percent nationally when fully effective. 

Projections of on-road emissions of SO2 in 2020 indicate that on-road sources will be 

responsible for less than one percent of the total SO2 emissions in 2020 in the 372 

potential PM2.5 nonattainment counties (based on 1999– 2001 air quality data). These 

projections confirm that the implementation of the fuel regulations discussed above will 

ensure that as a general matter of SO2 emissions from on-road sources remain at 

insignificant levels in all areas.” 

Although sulfate is a significant component to the PM2.5 nonattainment problem in North 

Carolina, the majority of the SO2 emissions in 2009 come from the stationary point source sector 

(see Figure 4-2). The mobile source sector only contributes one half of one percent (0.5 %) of 

the 2009 statewide SO2 emissions. This is consistent with what the USEPA stated above. 

Figure 4-2. North Carolina’s 2009 Statewide SO2 Emissions 

Nonroad

0.6%

Area

2.1%

Mobile

0.5%

Point

96.7%
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-5 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

Since the mobile source SO2 contribution is insignificant, the NCDAQ is not establishing 

MVEBs for this precursor. An affirmative insignificance finding from the USEPA only relieves 

the transportation partners from a regional emissions analysis for SO2 emissions for these areas 

and does not relieve them of the other transportation conformity requirements. The 

transportation partners will need to note the SO2 insignificance finding (if found adequate and 

approved by the USEPA) in future conformity determinations. 

4.2.4 Direct PM2.5 Emissions 

40 CFR 93.109(k) in the Transportation Conformity Rule Amendments for the new 8-hour ozone 

and fine particulate matter NAAQSs addresses areas with insignificant motor vehicle emissions 

as follows, 

“Notwithstanding the other paragraphs in this section, an area is not required to satisfy 

a regional emissions analysis for §93.118 and/or §93.119 for a given pollutant/precursor 

and NAAQS, if EPA finds through the adequacy or approval process that a SIP 

demonstrates that regional motor vehicle emissions are an insignificant contributor to 

the air quality problem for that pollutant/precursor and NAAQS. The SIP would have to 

demonstrate that it would be unreasonable to expect that such an area would experience 

enough motor vehicle emissions growth in that pollutant/precursor for a NAAQS 

violation to occur.” 

The rule suggests that such a finding would be based on a number of factors, including the 

percentage of motor vehicle emissions in the context of the total SIP inventory, the current state 

of air quality as determined by monitoring data for that NAAQS, the absence of SIP motor 

vehicle control measures, and historical trends and future projections of the growth of motor 

vehicle emissions. Although there is an inspection and maintenance program in the 

nonattainment areas, this control measure does not control primary PM2.5, but rather is in place to 

reduce the ozone precursors. 

The NCDAQ believes strongly that the primary PM2.5 emissions from mobile sources do not 

contribute significantly to the PM2.5 nonattainment problem. However, the USEPA has indicated 

they will not approve a SIP that does not set MVEBs for primary PM2.5 for the Triad 

nonattainment area. Therefore, the NCDAQ will establish county level MVEBs for primary 

PM2.5 for the Triad area. The sections that follow discuss the insignificance of PM2.5 emissions. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-6 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

The attainment modeling for the Hickory and the Triad PM2.5 nonattainment areas was submitted 

to the USEPA on August 21, 2009. In conjunction with that modeling the NCDAQ examined 

the sources of PM2.5 emissions and their contribution to PM2.5 formation in the nonattainment 

counties. This was accomplished using the 2009 emissions inventories developed for the 

attainment demonstration modeling. Figure 4-3 provides the percent contributions from point, 

area, nonroad mobile and on-road mobile source sectors for the Hickory nonattainment area. 

Figure 4-3. Hickory Area 2009 Primary PM2.5 Emissions 

The 2009 on-road mobile PM2.5 emissions contributed only 1.6% of the total PM2.5 emissions for 

the Hickory area. Therefore, it is demonstrated that the PM2.5 emissions compared to the total 

PM2.5 emissions are insignificant. It should be noted that the mobile source PM2.5 emissions 

slightly decrease from 2002 to 2009 despite an increase in VMT. 

The NCDAQ performed sensitivity modeling in order to address the challenge of Section 

93.109(k) in the Transportation Conformity Rule Amendments, “The SIP would have to 

demonstrate that it would be unreasonable to expect enough motor vehicle emissions growth in 

that pollutant/precursor for a NAAQS violation to occur”. The sensitivity modeling showed that 

with a doubling of the mobile source PM2.5 emissions there was no change in the air quality 

modeling results. This sensitivity modeling is discussed in more detail in Appendix C.3. 

Based on the information discussed above, the NCDAQ believes that the on-road mobile PM2.5

emissions are insignificant contributors to the PM2.5 nonattainment problem. Emission estimates 

indicate that the on-road mobile PM2.5 emissions are a small percentage of the total PM2.5

emissions in the Hickory nonattainment area. On-road mobile PM2.5 emissions are projected to 

1.59%

68.70%

1.49%

28.22%

Mobile

Point

Area

Nonroad
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-7 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

decrease into the future notwithstanding VMT increases. Air quality modeling sensitivities show 

that doubling the mobile source PM2.5 emissions has very little effect on the future design values. 

The NCDAQ considers it unreasonable to expect that the Hickory PM2.5 nonattainment area will 

experience enough motor vehicle PM2.5 emissions growth for a future PM2.5 violation to occur 

due to mobile sources. 

Due to above analysis and agreement from the USEPA, budgets for direct PM2.5 will not be set 

for the Hickory nonattainment area. An affirmative insignificance finding from the USEPA only 

relieves the transportation partners from a regional emissions analysis for PM2.5 emissions for 

this area and does not relieve them of the other transportation conformity requirements. The 

transportation partners will need to note the PM2.5 insignificance finding (if found adequate and 

approved by the USEPA) in future conformity determinations. 

4.3 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 mobile and nonroad mobile) and 

the projected level of emissions from all source categories. The safety margins for both the 

Hickory and Triad areas are listed in Table 3-21 and 3-22. 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 NCDAQ has decided to allocate a portion of the safety margin to the MVEB to allow for 

unanticipated growth in VMT, changes to vehicle mix assumptions, etc. that will influence the 

emission estimations. Since NOx is a precursor to ozone, the NCDAQ has decided to limit the 

amount of the safety margin allocated to the MVEBs. For 2011 and 2021, the NCDAQ has 

added an additional 10% and 20%, respectively, to the NOx MVEBs. This is consistent with 

how the NCDAQ has handled NOX MVEBs in ozone maintenance plans. 

Since the NCDAQ does not believe that mobile source PM2.5 emissions are a significant 

contributor to PM2.5 nonattainment, the 2011 and 2021 MVEBs for the Triad nonattainment area 

will be set at the 2008 mobile source PM2.5 emission levels. 

4.4 MOTOR VEHICLE EMISSION BUDGETS 

As part of the consultation process on setting MVEBs, the NCDAQ sent out a request for 

comment on setting the geographic extent of the MVEBs to all of the transportation partners. A 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-8 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

copy of the letter can be found in Appendix B. In the letter, the NCDAQ expressed its 

preference for setting county level budgets and the reasons why the NCDAQ believed county 

level budgets were appropriate. 

The NCDAQ received comments from the Greensboro Urban Area Metropolitan Planning 

Organization (GUAMPO) regarding the geographic extent of the MVEBs. The GUAMPO was 

in favor of having county level MVEBs. A copy of the letter received can be found in 

Appendix B. Therefore, the NCDAQ decided to move forward with setting county-by-county 

MVEBs. 

Additionally, there was discussion through the interagency consultation process on the years to 

set MVEBs for the Hickory and Triad PM2.5 maintenance plans. 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, 2021). Through the interagency consultation process, it was 

decided that MVEBs would be set for the year 2011 for both the Hickory and Triad PM2.5

nonattainment areas. 

Although the emissions up to this point have been expressed in terms of tons per year, the 

MVEBs will be set in terms of kilograms (kg) per year. In past conformity exercises, there have 

been some issues with conversion to tons, as well as concerns with how the MVEBs were 

rounded to the hundredth place. Setting MVEBs in kilograms will avoid these issues in future 

conformity determinations. Additionally, setting the MVEBs in kilograms was agreed to as part 

of the interagency consultation process. 

The table below shows the counties with their on-road mobile PM2.5 and NOx emissions 

expressed in kilograms per year and the corresponding tons per year values for 2011 and 2021. 

Table 4-1. On-Road Mobile Source PM2.5 Emissions 

County Kilograms/year Tons/year 

2011 2021 2011 2021 

Davidson 109,769 54,431 121 60 

Guilford 299,371 166,015 330 183 

Triad Total 409,140 220,446 451 243 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-9 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4-2. On-Road Mobile Source NOx Emissions 

County Kilograms/year Tons/year 

2011 2021 2011 2021 

Catawba 3,633,274 1,863,357 4,005 2,054 

Davidson 3,714,921 1,790,782 4,095 1,974 

Guilford 10,121,459 5,258,042 11,157 5,796 

Triad Total 13,836,380 7,048,824 15,252 7,770 

The NCDAQ will set MVEB, for transportation conformity purposes, as county budgets within 

the Hickory and Triad maintenance areas for 2011 and 2021. Tables 4-3 through 4-5 below list 

out the MVEBs in kilograms per year, for transportation conformity purposes, by county for the 

years 2011 and 2021. Upon the USEPA’s affirmative adequacy finding for these county level 

sub-area MVEBs, these MVEBs will become the applicable MVEBs for each county. 

Table 4-3 Catawba County MVEB 

 2011 2021 

NOx Emissions (kg/year)

Base Emissions 3,633,274 1,863,357 

Safety Margin Allocated to MVEB 363,327 372,671 

NOx Conformity MVEB 3,996,601 2,236,028 

Table 4-4 Davidson County MVEB 

 2011 2021 

NOx Emissions (kg/year)

Base Emissions 3,714,921 1,790,782 

Safety Margin Allocated to MVEB 371,492 358,156 

NOx Conformity MVEB 4,086,413 2,148,938 

PM2.5 Emissions (kg/year)

Base Emissions 109,769 54,431 

Safety Margin Allocated to MVEB 43,544 98,882 

PM2.5 Conformity MVEB 153,313 153,313 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-10 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4-5 Guilford County MVEB 

 2011 2021 

NOx Emissions (kg/year)

Base Emissions 10,121,459 5,258,042 

Safety Margin Allocated to MVEB 1,012,146 1,051,608 

NOx Conformity MVEB 11,133,605 6,309,650 

PM2.5 Emissions (kg/year)

Base Emissions 299,371 166,015 

Safety Margin Allocated to MVEB 122,470 255,826 

PM2.5 Conformity MVEB 421,841 421,841 

4.5 NEW SAFETY MARGINS 

For the Hickory nonattainment area, a total of 363,327 kg/year (400 tons/year) and 

372,671 kg/year (411 tons/year) of the 2011 and 2021 NOx safety margins, respectively, were 

added to the NOX MVEBs. 

 For the Triad nonattainment area, a total of 1,383,638 kg/year (1,525 tons/year) and 

1,409,764 kg/year (1,554 tons/year) of the 2011 and 2021 NOx safety margins, respectively, were 

added to the Triad NOX MVEBs. For PM2.5, a total of 166,014 kg/year (183 tons/year) and 

354,708 kg/year (391 tons/year) of the 2011 and 2021 PM2.5 safety margins, respectively, were 

added to the Triad PM2.5 MVEBs. 

Table 4-6 New Safety Margins for the Hickory PM2.5 nonattainment area 

Year NOx (tons/year) PM2.5 (tons/year) 

2011 -3,637 -67 

2014 -5,073 -126 

2017 -5,917 -180 

2021 -6,207 -253 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 4-11 

Supplement to Redesignation Demonstration and Maintenance Plan December 22, 2010 

Table 4-7 New Safety Margins for the Triad PM2.5 nonattainment area 

Year NOx (tons/year) PM2.5 (tons/year) 

2011 -3,722 -94 

2014 -9,150 -490 

2017 -12,270 -682 

2021 -13,205 -528 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 5-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

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 Hickory and Triad PM2.5

nonattainment area.

5.2 EVIDENCE OF COMPLIANCE 

The following rules regulating emissions of SO2 and/or NOx in PM2.5 nonattainment area 

counties have been approved, or have been submitted with a request to be approved, as part of 

the SIP: 

15A NCAC 2D .0530, Prevention of Significant Deterioration 

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 .1900, Open Burning 

 15A NCAC 2D .2000, Transportation Conformity 

15A NCAC 2D .2400 Clean Air Interstate Rules 

Section 15A NCAC 2D .1000 also regulates emissions from motor vehicles in the counties near 

the Hickory and Triad nonattainment area and requires the use of the on board diagnostic system, 

which will indicate 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 require reduction in emissions, they 

do ensure that federal actions do not hinder attainment or maintenance of the NAAQS. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 5-2 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

North Carolina has adopted an open burning rule, 15A NCAC 2D .1900, which prohibits open 

burning of vegetative material during Air Quality Action Days of Code Orange or higher in 

forecasted areas of the State. Particle pollution forecasts are issued for the Hickory and Triad 

areas year-round; 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 Call rules. 

This Section replaces the NOx SIP Call rules beginning January 1, 2009. 

Another important set of rules that may result in control of some particulates that are air toxics in 

North Carolina in these counties is Section 15A NCAC 2D .1100, Control of Toxic Air 

Pollutants. These rules, however, have not been submitted to the USEPA to be approved as part 

of the SIP. 

There are two other rules that control emissions of some particulates in these areas. They are 

15A NCAC 2D .0524, New Source Performance Standards. Also, rule 2D.1111, Maximum 

Achievable Control Technology applies to control of emissions of HAP, some of which are 

particulates. They are not part of the SIP, but the USEPA 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 USEPA delegation.) 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 6-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

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 and Part D of the 

Act 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 USEPA in its latest guidance on meeting redesignation requirements as contained in a 

memorandum from John Calcagni, Director, Air Quality Management Division, Office of Air 

Quality Planning and Standards to the USEPA 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 NCDAQ commits to continue 

operating the current fine particulate matter monitors in the Hickory and Triad nonattainment 

areas, providing sufficient funding is available for continued operation. Any monitor shutdowns 

or relocations will only be made with the approval of the USEPA. 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. 

NCDAQ believes that North Carolina has met all of the requirements of Section 110 and Part D. 
Hickory and Greensboro/Winston-Salem/High Point Annual PM2.5 7-1 

Redesignation Demonstration and Maintenance Plan December 18, 2009 

7.0 CONCLUSION 

The most recent three years of fine particulate matter monitoring data for the both the Hickory 

and Greensboro/Winston-Salem/High Point (Triad) nonattainment areas demonstrate compliance 

with the NAAQS for annual fine particulate matter. Since the 1990’s, there have been 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 both the Hickory and Triad 

areas. Additionally, the maintenance plan demonstrates that the projected emissions inventories 

for 2021, the final year of the maintenance plan and ten years beyond the expected redesignation 

year, as well as the interim years, are all less than the base year emissions inventory. Therefore, 

maintenance of the annual fine particulate matter NAAQS has also been demonstrated. 

This redesignation demonstration and maintenance plan has been prepared to meet the 

requirements of the 1990 Clean Air Act Amendments.