Regional Haze State Implementation Plan 

for 

North Carolina Class I Areas 

Prepared by 

North Carolina Department of Environment and Natural Resources 

Division of Air Quality 

December 17, 2007
Regional Haze SIP i 

for North Carolina Class I Areas December 17, 2007 

Preface: This document contains summaries of the technical analyses that will be used by 

North Carolina’s Division of Air Quality to support the regional haze state implementation plan 

pursuant to §§107(d)(3)(D) and (E) of the Clean Air Act, as amended. 
Regional Haze SIP ii 

for North Carolina Class I Areas December 17, 2007 

EXECUTIVE SUMMARY 

Introduction 

Regional haze is pollution that impairs visibility over a large region, including national parks, 

forests, and wilderness areas (many termed “Class I” areas). Regional haze is caused by sources 

and activities emitting fine particles and their precursors, often transported over large regions. 

Particles affect visibility through the scattering and absorption of light. Reducing fine particles 

in the atmosphere is an effective method of improving visibility. In the southeast, the most 

important sources of haze-forming emissions are coal-fired power plants, industrial boilers and 

other combustion sources, but also include mobile source emissions, area sources, fires, and 

wind blown dust. 

An easily understood measure of visibility to most people is visual range. Visual range is the 

greatest distance, in kilometers or miles, at which a dark object can be viewed against the sky. 

However, the most useful measure of visibility impairment is light extinction, which affects the 

clarity and color of objects being viewed. The measure used by the regional haze rule is the 

deciview (dv), calculated directly from light extinction using a logarithmic scale. 

The regional haze rule requires states to demonstrate reasonable progress toward meeting the 

national goal of a return to natural visibility conditions by 2064. The rule directs states to 

graphically show what would be a “uniform rate of progress”, also known as the “glide path”, 

toward natural conditions for each Class I area within the State and certain ones outside the 

State. 

North Carolina’s Class I areas 

North Carolina has five Class I areas within its borders: Great Smoky Mountains National Park, 

Joyce Kilmer-Slickrock Wilderness Area, Linville Gorge Wilderness Area, Shining Rock 

Wilderness Area, and Swanquarter Wildlife Refuge. Both the Great Smoky Mountains National 

Park and Joyce Kilmer-Slickrock Wilderness Area are located in both North Carolina and 

Tennessee. The figure below illustrates the location of these Class I areas. 
Regional Haze SIP iii 

for North Carolina Class I Areas December 17, 2007 

Visibility on the worst days at the mountain sites is generally between 28 and 30 dv, and 

visibility at Swanquarter is 25 dv. Natural background visibility on the worst days is between 11 

and 12 dv. 

State Implementation Plan Requirements 

States are required to submit state implementation plans (SIPs) to the United States 

Environmental Protection Agency that set out each states’ plan for meeting the national goal of a 

return to natural visibility conditions by 2064. The plan includes the states’ reasonable progress 

goals, expressed in deciviews, for visibility improvement at each affected Class I area for each 

10-year period until 2064. 

SIPs must include determinations of the baseline visibility conditions (expressed in deciviews) 

for the most impaired and least impaired days. In addition, states must include a monitoring 

strategy for measuring, characterizing, and reporting of regional haze visibility impairment. The 

long-term strategy includes enforceable emissions limitations, compliance schedules, and other 

measures as necessary to achieve the reasonable progress goals. States must also consider 

ongoing control programs, measures to mitigate construction activities, source retirement and 

replacement schedules, smoke management techniques for agriculture and forestry, and 

enforceability of specific measures. 

The SIPs for the first review period are due December 17, 2007. These plans will cover longterm strategies for visibility improvement between baseline conditions in 2000-2004 and 2018. 

States are required to evaluate progress toward reasonable progress goals every 5 years to assure 

that installed emissions controls are on track with emissions reduction forecasts in each SIP. 

Federal and State Control Requirements 

There are significant control programs being implemented between the baseline period and 2018. 

These programs will all reduce the particulate precursor emissions that affect visibility in the 

Class I areas, and include: the Clean Air Interstate Rule (CAIR), the NOx SIP Call, the North 

Carolina Clean Smokestacks Act, Georgia Multi-Pollutant Rule, consent agreements with Tampa 

Electric, Virginia Electric and Power Company, Gulf Power and American Electric Power, onehour ozone SIPs submitted by Atlanta, Birmingham, and Northern Kentucky, NOx RACT in 8-

hour nonattainment area SIPs, heavy duty diesel (2007) engine standard (for on-road trucks and 

buses), Tier 2 tailpipe standards for on-road vehicles, large spark ignition and recreational 

vehicle rule, nonroad diesel rule, and various Federal Maximum Achievable Control Technology 

regulations. 

The regional haze rule also requires states to determine best available retrofit technology 

(BART) for certain facilities. Fifteen of North Carolina’s seventeen BART-eligible sources were 

able to demonstrate that they did not cause or contribute to visibility impairment. Further BART 

analysis of two other sources, PCS Phosphate in Aurora, North Carolina and Blue Ridge Paper in 

Canton, North Carolina, demonstrated that no additional controls were required at this time at 

either facility. 
Regional Haze SIP iv 

for North Carolina Class I Areas December 17, 2007 

Conclusion 

At all five Class I areas in North Carolina, visibility improvements on the worst days are 

expected to be better than the uniform rate of progress glidepath by 2018 based solely on 

reductions from existing and planned emissions controls. Additionally, the visibility is expected 

to improve for the best days for all of the North Carolina Class I areas. The table below displays 

the 2018 reasonable progress goals for the North Carolina Class I areas. 

Class I Area 

Baseline 

Visibility 

Worst Days 

Reasonable 

Progress Goal - 

Worst Days 

Baseline 

Visibility 

Best Days 

Reasonable 

Progress Goal - 

Best Days 

Great Smoky Mountains 

National Park 30.3 23.7 13.6 12.2 

Joyce Kilmer-Slickrock 

Wilderness Area 30.3 23.7 13.6 12.2 

Linville Gorge 

Wilderness Area 28.8 22.0 11.1 9.6 

Shining Rock Wilderness 

Area 28.5 22.1 7.7 6.9 

Swanquarter Wildlife 

Refuge 24.7 20.4 12.0 11.0 
Regional Haze SIP v 

for North Carolina Class I Areas December 17, 2007 

ACKNOWLEDGEMENTS 

This regional haze plan has been primarily produced by the Planning Section of the North 

Carolina Division of Air Quality (NCDAQ), with significant help from the VISTAS (Visibility 

Improvement – State and Tribal Association of the Southeast) technical coordinator. 

Additionally, the NCDAQ was lucky to have, on Interagency Personnel Agreements, a couple of 

U. S. Environmental Protection Agency (USEPA) staff that also contributed to the process. 

Below are the names of the staff involved in this process. 

NCDAQ Staff:

Planning Section

Michael Abraczinskas 

Pat Bello 

George Bridgers 

Joelle Burleson 

Victoria Chandler 

Chris Misenis 

Bebhinn Do 

Janice Godfrey 

Phyllis Jones 

Matt Mahler 

Donnie Redmond 

Nick Witcraft 

Bob Wooten 

Ming Xie 

Kathy Kaufman, on rotation from USEPA 

Rosalina Rodriguez, on rotation from USEPA 

Thom Allen, Rules Development Branch Supervisor 

Laura Boothe, Attainment Planning Branch Supervisor 

Sheila Holman, Planning Section Chief 

Permits Section

Tom Anderson 

Chuck Buckler 

Jerry Freeman 

Fern Patterson 

Wallace Pitts 

Mark Yoder 

VISTAS Staff:

Pat Brewer, VISTAS Technical Coordinator 
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for North Carolina Class I Areas December 17, 2007 

Additionally, there were a number of NCDAQ staff and other agencies that provided support 

during the development of the regional haze plan. These staff are acknowledge below: 

IT Support

Holly Groce, NCDAQ, Business Office 

George Halsey, NCDAQ, Business Office 

Regional Office Support

Brendan Davey, Asheville Regional Office 

Robert Fisher, Washington Regional Office Supervisor, Hearing Officer 

Paul Muller, Asheville Regional Office Supervisor, Hearing Officer 

Brad Newland, Wilmington Regional Office 

Local Program Support

Ashley Featherstone, Western North Carolina Regional Air Quality Agency 

Office Assistant Support

Mildred Mitchell, NCDAQ, Planning Section 

Angela Terry, NCDAQ, Planning Section 

Management Support

Brock Nicholson, NCDAQ, Deputy Director 

Keith Overcash, NCDAQ, Director 

John Hornback, VISTAS, Executive Director 

The NCDAQ worked closely with those states in the VISTAS region through technical 

coordination, technical discussions and technical support. This regional haze plan could not 

have been completed on time without the combined efforts of the staff from these state agencies: 

VISTAS State Agencies:

Alabama Department of Environmental Management 

Florida Department of Environmental Protection 

Georgia Department of Natural Protection 

Kentucky Department of Environmental Protection 

Mississippi Department of Environmental Quality 

South Carolina Department of Health and Environmental Control 

Tennessee Department of Environmental Conservation 

Virginia Department of Environmental Quality 

West Virginia Department of Environmental Protection 
Regional Haze SIP vii 

for North Carolina Class I Areas December 17, 2007 

Finally, this could not have been completed without the expertise and dedication of the VISTAS 

contractors that performed the technical work. 

Contractors:

Air Resource Specialists: Monitoring Data Analysis 

Alpine Geophysics: Emissions and Air Quality Modeling, Technical Advisor for Emissions 

Inventory 

Atmospheric Research and Analysis, Inc.: Operation of continuous monitors at Millbrook, NC 

Baron Applied Meteorology: Meteorological Modeling 

Desert Research Institute: Carbon Source Attribution including sample filter preparation, sample 

analysis using Gas Chromatography and Mass Spectrometry, source attribution using Chemical 

Mass Balance analyses and Positive Matrix Factorization 

Earth Tech, Inc: BART Modeling, CALPUFF Training 

ENVIRON: Emissions and Air Quality Modeling 

Georgia Institute of Technology: Emissions and Air Quality modeling sensitivities 

Harvard University: GEOS-Chem global model 

Ivar Tombach, Environmental Consultant 

ICF Consulting: Integrated Planning Model for future electric utility generation 

MACTEC: 2002, 2009, and 2018 Emissions Inventory and Projections, CALPUFF training 

E.H. Pechan and Associates: 2002 Mobile Inventory 

Research Triangle Institute: Chemical Analysis of Monitoring Samples 

System Applications International: Meteorological Characterization 

Tennessee Valley Authority: Operation of continuous monitors at Great Smoky Mountain 

National Park and preparation of final project report and draft manuscript 

TRC, Inc: BART Modeling 

University of California, Riverside: Emissions and Air Quality Modeling 

Woods Hole: Analysis of Carbon 14 isotope in carbon samples as part of carbon source 

attribution project 
Regional Haze SIP viii 

for North Carolina Class I Areas December 17, 2007 

TABLE OF CONTENTS 

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

1.1 What is regional haze?.......................................................................................................... 1 

1.2 What are the requirements under the Clean Air Act for addressing regional haze?............. 1 

1.3 General overview of regional haze SIP requirements .......................................................... 2 

1.4 Class I areas in North Carolina............................................................................................. 4 

1.5 State and Federal Land Manager coordination..................................................................... 5 

2.0 ASSESSMENT OF BASELINE AND CURRENT CONDITIONS AND ESTIMATE OF 

NATURAL BACKGROUND CONDITIONS IN CLASS I AREAS ................................... 7 

2.1 Estimating Natural Conditions for North Carolina Class I Areas ........................................ 8 

2.2 Estimating Baseline Conditions for North Carolina Class I Areas....................................... 9 

2.3 Summary of Natural Background and Baseline Conditions for North Carolina Class I 

Areas................................................................................................................................. 10 

2.4 Pollutant Contributions to Visibility Impairment (2000-2004 Baseline Data)................... 11 

3.0 GLIDEPATHS TO NATURAL CONDITIONS IN 2064...................................................... 15 

3.1 Glidepaths for Class I Areas in North Carolina.................................................................. 16 

4.0 TYPES OF EMISSIONS IMPACTING VISIBILITY IMPAIRMENT IN NORTH 

CAROLINA CLASS I AREAS............................................................................................ 19 

4.1 Baseline Emissions Inventory............................................................................................. 19

4.1.1 Stationary Point Sources ............................................................................................ 20 

4.1.2 Stationary Area Sources ............................................................................................. 21 

4.1.3 Off-Road Mobile Sources .......................................................................................... 22 

4.1.4 Highway Mobile Sources ........................................................................................... 22 

4.1.5 Biogenic Emission Sources........................................................................................ 22 

4.1.6 Summary 2002 Baseline Emissions Inventory for North Carolina............................ 23 

4.1.7 Model Performance Improvements through Emissions Inventory Improvements .... 23 

4.2 Assessment of Relative Contributions from Specific Pollutants and Sources Categories . 24 

5.0 REGIONAL HAZE MODELING METHODS AND INPUTS ............................................. 25 

5.1 Analysis Method................................................................................................................. 25 

5.2 Model Selection .................................................................................................................. 25 

5.2.1 Selection of Photochemical Grid Model .................................................................... 26 

5.2.2 Selection of Meteorological Model............................................................................ 27 

5.2.3 Selection of Emissions Processing System ................................................................ 28 

5.3 Selection of the Modeling Year.......................................................................................... 29 

5.4 Modeling Domains ............................................................................................................. 31 

5.4.1 Horizontal Modeling Domain .................................................................................... 31 

5.4.2 Vertical Modeling Domain......................................................................................... 33 
Regional Haze SIP ix 

for North Carolina Class I Areas December 17, 2007 

6.0 MODEL PERFORMANCE EVALUATION......................................................................... 33 

6.1 Modeling Performance Goals, and Criteria ........................................................................ 34 

6.2 VISTAS Domain-Wide Performance ................................................................................. 35 

6.3 North Carolina Class 1 Areas Performance........................................................................ 39 

7.0 LONG-TERM STRATEGY FOR NORTH CAROLINA CLASS I AREAS........................ 44 

7.1 Overview of the Long-Term Strategy Development Process............................................. 44 

7.2 Expected Visibility Results in 2018 for North Carolina Class I Areas under existing and 

planned emissions controls............................................................................................... 45 

7.2.1 Federal and State Control Requirements.................................................................... 45 

7.2.2 Additional State programs to reduce emissions ......................................................... 48 

7.2.3 Projected 2009 and 2018 Emissions Inventories........................................................ 48 

7.2.4 Model Results for the 2018 Inventory Compared to the Uniform Rate of Progress 

Glidepaths for North Carolina Class I Areas ................................................................... 50 

7.3 Relative Contribution from International Emissions to Visibility Impairment in 2018 at 

VISTAS Class I areas....................................................................................................... 59 

7.4 Relative Contributions to Visibility Impairment: Pollutants, Source Categories, and 

Geographic Areas ............................................................................................................. 61

7.5 What Control Determinations Represent Best Available Retrofit Technology for Individual 

Sources?............................................................................................................................ 66 

7.5.1 BART-Eligible Sources in North Carolina ................................................................ 66 

7.5.2 Determination of Sources Subject to BART in North Carolina................................. 67 

7.5.3 Determination of BART Requirements for Subject-to-BART Sources..................... 70 

7.6 Relative Contributions to Visibility Impairment: Geographic Areas of Influence for North 

Carolina Class I Areas...................................................................................................... 71 

7.6.1 Back Trajectory Analyses .......................................................................................... 71 

7.6.2 Residence Time Plots ................................................................................................. 72 

7.6.3 SO2 Areas of Influence .............................................................................................. 73 

7.6.4 Emissions Sources within SO2 Areas of Influence.................................................. 74 

7.6.5 Specific Source Types in the Areas of Influence for North Carolina Class I Areas . 78 

7.7 Evaluating the Four Statutory Factors for Specific SO2 Emissions Sources in Each Area of 

Influence........................................................................................................................... 83 

7.8 Which Control Measures Represent Reasonable Progress for Individual Sources? .......... 85 

8.0 REASONABLE PROGRESS GOALS................................................................................... 93 

9.0 MONITORING STRATEGY................................................................................................. 94 

10.0 CONSULTATION PROCESS ............................................................................................. 98 

11.0 COMPREHENSIVE PERIODIC IMPLEMENTATION PLAN REVISIONS ................. 100 

12.0 DETERMINATION OF ADEQUACY OF THE EXISTING PLAN ................................ 102 
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for North Carolina Class I Areas December 17, 2007 

LIST OF APPENDICES 

Appendix A: VISTAS Memorandum of Understanding and Bylaws 

Appendix B: Conceptual Description 

Appendix C: Modeling Analysis Protocol and Quality Assurance Project Plan 

Appendix D: Emissions Preparation and Results 

Appendix E: Air Quality and Meteorological Preparations and Results 

Appendix F: Model Performance Evaluation 

Appendix G: Modeling Results and Supplemental Analysis 

Appendix H: Reasonable Progress Evaluation/Long Term Strategy 

Appendix I: Data Access 

Appendix J: Consultation Process 

Appendix K: Recommended Improvements 

Appendix L: BART Related Documentation 

Appendix M: VISTAS Modeling Reports 

Appendix N: Hearing Report, Comments Received and Responses 
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for North Carolina Class I Areas December 17, 2007 

1.0 INTRODUCTION 

1.1 What is regional haze? 

Regional haze is pollution from disparate sources that impairs visibility over a large region, 

including national parks, forests, and wilderness areas (156 of which are termed mandatory 

Federal “Class I” areas). Regional haze is caused by sources and activities emitting fine particles 

and their precursors. Those emissions are often transported over large regions. 

Particles affect visibility through the scattering and absorption of light, and fine particles – 

particles similar in size to the wavelength of light – are most efficient, per unit of mass, at 

reducing visibility. Fine particles may either be emitted directly or formed from emissions of 

precursors, the most important of which are sulfur dioxides (SO2) and nitrogen oxides (NOx). 

Reducing fine particles in the atmosphere is generally considered to be an effective method of 

reducing regional haze, and thus improving visibility. Fine particles also adversely impact 

human health, especially respiratory and cardiovascular systems. The United States 

Environmental Protection Agency (USEPA) has set national ambient air quality standards for 

daily and annual levels of fine particles with diameter smaller than 2.5 μm (PM2.5). In the 

southeast, the most important sources of PM2.5 and its precursors are coal-fired power plants, 

industrial boilers and other combustion sources. Other significant contributors to PM2.5 and 

visibility impairment include mobile source emissions, area sources, fires, and wind blown dust. 

1.2 What are the requirements under the Clean Air Act for addressing regional haze? 

In Section 169A of the 1977 Amendments to the Clean Air Act (CAA), Congress set forth a 

program for protecting visibility in Class I areas which calls for the “prevention of any future, 

and the remedying of any existing, impairment of visibility in mandatory Class I Federal areas 

which impairment results from manmade air pollution.” Congress adopted the visibility 

provisions to protect visibility in these 156 national parks, forests and wilderness areas. On 

December 2, 1980, the USEPA promulgated regulations to address visibility impairment 

(45 FR 80084). The 1980 regulations were developed to address visibility impairment that is 

“reasonably attributable” to a single source or small group of sources. These regulations 

represented the first phase in addressing visibility impairment and deferred action on regional 

haze that emanates from a variety of sources until monitoring, modeling and scientific 

knowledge about the relationships between pollutants and visibility impairment improved. 

In the 1990 Amendments to the CAA, Congress added section 169B and called on the USEPA to 

issue regional haze rules. The regional haze rule that the USEPA promulgated on July 1, 1999 

(64 FR 35713), revised the existing visibility regulations in order to integrate provisions 

addressing regional haze impairment and establish a comprehensive visibility protection program 

for Class I Federal areas. States are required to submit state implementation plans (SIPs) to the 

USEPA that set out each states’ plan for complying with the regional haze rule, including 

consultation and coordination with other states and with Federal Land Managers (FLMs). The 

timing of SIP submittal is tied to the USEPA’s promulgation of designations for the National 

Ambient Air Quality Standard (NAAQS) for fine particulate matter. States must submit a 
Regional Haze SIP 2 

for North Carolina Class I Areas December 17, 2007 

regional haze implementation plan to the USEPA within three years after the date of designation. 

Because the USEPA promulgated designation dates on December 17, 2004, regional haze SIPs 

must be submitted by December 17, 2007. 

The regional haze rule addressed the combined visibility effects of various pollution sources over 

a wide geographic region. This wide reaching pollution net meant that many states – even those 

without Class I areas – would be required to participate in haze reduction efforts. The USEPA 

designated five Regional Planning Organizations (RPOs) to assist with the coordination and 

cooperation needed to address the visibility issue. The RPO that makes up the southeastern 

portion of the contiguous United States is known as VISTAS (Visibility Improvement – State 

and Tribal Association of the Southeast), and include the following states: Alabama, Florida, 

Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West 

Virginia. 

Figure 1.2-1. Geographical Areas of Regional Planning Organizations 

1.3 General overview of regional haze SIP requirements 

The regional haze rule at 40 CFR 51.308(d) requires states to demonstrate reasonable progress 

toward meeting the national goal of a return to natural visibility conditions by 2064. As a guide 

for reasonable progress, the regional haze rule directs states to graphically show what would be a 

“uniform rate of progress” toward natural conditions for each mandatory Class I Federal area 

within the State and/or for each mandatory Class I Federal area located outside the State, which 

may be affected by emissions from sources within the State. States are to establish baseline 

visibility conditions for 2000-2004, natural background visibility conditions in 2064, and the rate 
Regional Haze SIP 3 

for North Carolina Class I Areas December 17, 2007 

of uniform progress between baseline and background conditions. The uniform rate of progress 

is also known as the “glidepath.” 

The regional haze rule then requires states to establish reasonable progress goals, expressed in 

deciviews, for visibility improvement at each affected Class I area covering each 

(approximately) 10-year period until 2064. The goals must provide for reasonable progress 

towards achieving natural visibility conditions, provide for improvement in visibility for the 

most impaired days over the period of the implementation plan, and ensure no degradation in 

visibility for the least impaired days over the same period (see 40 CFR 51.308(d)(1)). 

In order to ensure that visibility goals are properly met and set, SIPs plans must include 

determinations, for each Class I area, of the baseline visibility conditions (expressed in 

deciviews) for the most impaired and least impaired days. SIPs must also contain supporting 

documentation for all required analyses used to calculate the degree of visibility impairment 

under natural visibility conditions for the most impaired and least impaired days (see 40 CFR 

51.308(d)(2)). In addition, states must include a monitoring strategy for measuring, 

characterizing, and reporting of regional haze visibility impairment that is representative of all 

mandatory Class I Federal areas within the state (see 40 CFR 51.308(d)(4)).

This first set of reasonable progress goals must be met through measures contained in the state’s 

long-term strategy covering the period from the present until 2018. The long-term strategy 

includes enforceable emissions limitations, compliance schedules, and other measures as 

necessary to achieve the reasonable progress goals, including all controls required or expected 

under all federal and state regulations by 2009 and by 2018. During development of the longterm strategy, states are also required to consider specific factors such as the above mentioned 

ongoing control programs, measures to mitigate construction activities, source retirement and 

replacement schedules, smoke management techniques for agriculture and forestry, and 

enforceability of specific measures (see 40 CFR 51.308(d)(3)). 

In addition, a specific component of each state’s first long-term strategy is dictated by the 

specific best available retrofit technology (BART) requirements in 40 CFR 51.308(e) of the 

regional haze rule. The regional haze rule at 40 CFR 51.308(e) requires states to include a 

determination of BART for each BART-eligible source in the State that emits any air pollutant, 

which may reasonably be anticipated to cause or contribute to any impairment of visibility in any 

mandatory Class I Federal area. The Clean Air Act section 169A(b) defines BART-eligible 

sources as sources in 26 specific source categories, in operation within a 15-year period prior to 

enactment of the 1977 Clean Air Act Amendments. States must determine BART according to 

five factors set out in section 169A(g)(7) of the Clean Air Act. Emission limitations representing 

BART and schedules for compliance with BART for each source subject to BART must be 

included in the long-term strategy. 

The SIPs for the first review period are due December 17, 2007. These plans will cover longterm strategies for visibility improvement between baseline conditions in 2000-2004 and 2018. 

States are required to evaluate progress toward reasonable progress goals every 5 years to assure 

that installed emissions controls are on track with emissions reduction forecasts in each SIP. The 

first interim review would be due to the USEPA in December 2012. If emissions controls are not 
Regional Haze SIP 4 

for North Carolina Class I Areas December 17, 2007 

on track to meet SIP forecasts, then states would need to take action to assure emissions controls 

by 2018 will be consistent with the SIP or to revise the SIP to be consistent with the revised 

emissions forecast. 

The USEPA provided several guidance documents listed below to assist the states in 

implementation of the regional haze rule requirements. NC followed these guidance documents 

in developing the technical analyses reported in this plan. 

• Guidance for Tracking Progress Under the Regional Haze Rule (EPA-454/B-03-004, 

September 2003). 

• Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Rule 

(EPA-454/B-03-005, September 2003). 

• Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air 

Quality Goals for Ozone, PM2.5 and Regional Haze (EPA, 2007). 

• Guidance for Setting Reasonable Progress Goals Under the Regional Haze Program 

(EPA, June 2007). 

1.4 Class I areas in North Carolina 

North Carolina has five Class I areas within its borders: Great Smoky Mountains National Park, 

Joyce Kilmer-Slickrock Wilderness Area, Linville Gorge Wilderness Area, Shining Rock 

Wilderness Area, and Swanquarter Wildlife Refuge. The North Carolina Division of Air Quality 

(NCDAQ) in the North Carolina Department of Environment and Natural Resources is 

responsible for developing the Regional Haze SIP. This SIP establishes reasonable progress 

goals for visibility improvement at each of these Class I areas, and a long-term strategy that will 

achieve those reasonable progress goals within the first regional haze planning period. The 

Great Smoky Mountains and Joyce Kilmer-Slickrock are located in both Tennessee and North 

Carolina. For the Great Smoky Mountains, both states are sharing the lead for setting goals and 

for Joyce Kilmer-Slickrock, North Carolina is the lead. 

Figure 1.4-1. North Carolina’s Class I areas 
Regional Haze SIP 5 

for North Carolina Class I Areas December 17, 2007 

In developing this SIP, the NCDAQ has also considered that emission sources outside of North 

Carolina may affect visibility at these North Carolina Class I areas, and that emission sources 

within North Carolina may affect visibility at Class I areas in neighboring states. Through 

VISTAS, the southeastern states have worked together to assess state-by-state contributions to 

visibility impairment in specific Class I areas, including those in North Carolina and those 

affected by emissions from North Carolina. This technical work is discussed further in 

Sections 5, 6, and 7. Consultations to date between North Carolina and other states and the 

FLMs are summarized in Section 10; consultations are ongoing. 

Prior to VISTAS, the southern states cooperated in a voluntary regional partnership to identify 

and recommend reasonable measures to remedy existing and prevent future adverse effects from 

human-induced air pollution on the air quality related values of the Southern Appalachian 

Mountains. States cooperated with the FLMs, the USEPA, industry, environmental 

organizations and academia to complete a technical assessment of the impacts of acid deposition, 

ozone, and fine particles on sensitive resources in the Southern Appalachians. The (Southern 

Appalachian Mountain Initiative) SAMI Final Report was delivered in August 2002. The SAMI 

Assessment concluded that ammonium sulfate is the major contributor to visibility impairment in 

the Southern Appalachian Mountains and to improve visibility, it is most important to reduce 

SO2 emissions. SAMI also concluded that reducing ammonia emissions would be helpful to 

reduce ammonium nitrate contributions to visibility impairment. Emissions controls for organic 

carbon, elemental carbon, and soil were expected to be less important for improving visibility. 

The SAMI modeling found that on the haziest days, much of the benefit of emissions reductions 

would occur in the state where emissions reductions were made. Emissions in surrounding the 

SAMI states and states outside the SAMI region also contribute to air quality in the SAMI Class 

I areas. The SAMI states supported strong national multi-pollutant legislation to accomplish its 

mission. Emissions reductions to meet national health standards for ozone and fine particles 

were expected to also improve air quality in the Southern Appalachian Mountains. The SAMI 

states committed to consider air quality benefits in the Southern Appalachians as they developed 

SIPs for the health standards. 

In 2002, the North Carolina legislation passed the North Carolina Clean Smokestack Act (CSA) 

that requires North Carolina utilities to reduce emissions of SO2 and NOx. The SAMI analyses 

and recommendations supported development of the North Carolina CSA. Congress considered 

several legislative bills to reduce SO2 and NOx from electric generating utilities. In 2004, the 

USEPA promulgated the Clean Air Interstate Rule (CAIR) to require emissions reductions for 

SO2 and NOx from electric generating utilities in 26 eastern states. The CAIR rule allows for 

interstate trading of emissions to find cost effective reductions. These reductions will improve 

visibility in Class I areas in North Carolina. 

1.5 State and Federal Land Manager coordination 

As required by 40 CFR §51.308(i), the regional haze SIP must include procedures for continuing 

consultation between the States and FLMs on the implementation of the visibility protection 

program, including development and review of implementation plan revisions and 5-year 

progress reports, and on the implementation of other programs having the potential to contribute 

to impairment of visibility in any mandatory Class I Federal area within the State. The three 
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for North Carolina Class I Areas December 17, 2007 

FLMs are the United States Department of Interior’s (USDI’s) Fish and Wildlife Service (FWS) 

and National Park Service (NPS) and the United States Department of Agriculture’s (USDA’s) 

Forest Service (FS). 

Successful implementation of a regional haze program will involve long-term regional 

coordination among States. VISTAS was formed in 2001 to address regional haze and visibility 

problems in the southeastern United States. Jurisdictions represented by VISTAS members 

include the Eastern Band of Cherokee Indians; the States of Alabama, Florida, Georgia, 

Kentucky, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia; 

and the local air pollution control programs located in these States. A copy of the VISTAS 

Memorandum of Agreement and Bylaws is enclosed as Appendix A. 

The objectives of the VISTAS project are to establish natural background visibility conditions 

across the mandatory Class I Federal areas, identify current visibility impairment levels, analyze 

emission control levels that will achieve interim visibility goals, and provide adequate 

documentation to member agencies so that they can develop their regional haze State/Tribal 

Implementation Plans (SIP/TIP). Figure 1.5-1 shows the 18 mandatory Class I Federal areas in 

the VISTAS Region, where visibility is an important value. Table 1.5-1 lists these Class I areas 

and the reported acreage associated with the Class I areas. 

Figure 1.5-1. Class I Areas in the VISTAS Region 
Regional Haze SIP 7 

for North Carolina Class I Areas December 17, 2007 

Table 1.5-1 Mandatory Class I Federal Areas in the VISTAS Region 

State Area Name Acreage Federal Land 

Manager 

Alabama Sipsey Wilderness 24,922 USDA-FS 

Chassahowitzka Wilderness 23,579 USDI-FWS 

Florida Everglades National Park 1,397,429 USDI-NPS 

St. Marks Wilderness 17,350 USDI-FWS 

Cohutta Wilderness 36,977 USDA-FS 

Georgia Okefenokee Wilderness 353,981 USDI-FWS 

Wolf Island Wilderness 5,126 USDI-FWS 

Kentucky Mammoth Cave National Park 51,303 USDI-NPS 

Great Smoky Mountains National Park 273,551 USDI-NPS 

Joyce Kilmer-Slickrock Wilderness 13,562 USDA-FS 

Linville Gorge Wilderness 11,786 USDA-FS 

Shining Rock Wilderness 18,483 USDA-FS 

North Carolina 

Swanquarter Wilderness 8,785 USDI-FWS 

South Carolina Cape Romain Wilderness 29,000 USDI-FWS 

Great Smoky Mountains National Park 241,207 USDI-NPS Tennessee 

Joyce Kilmer-Slickrock Wilderness 3,832 USDA-FS 

James River Face Wilderness 8,886 USDA-FS Virginia Shenandoah National Park 190,535 USDI-NPS 

Dolly Sods Wilderness 10,215 USDA-FS West Virginia Otter Creek Wilderness 20,000 USDA-FS 

2.0 ASSESSMENT OF BASELINE AND CURRENT CONDITIONS AND 

ESTIMATE OF NATURAL BACKGROUND CONDITIONS IN CLASS I 

AREAS 

The goal of the regional haze rule is to restore natural visibility conditions to the 156 Class I 

areas identified in the 1977 Clean Air Act Amendments. 40 CFR 51.301(q) defines natural 

conditions: “Natural conditions include naturally occurring phenomena that reduce visibility as 

measured in terms of light extinction, visual range, contrast, or coloration.” The regional haze 

SIPs must contain measures that make “reasonable progress” toward this goal by reducing 

anthropogenic, i.e., manmade, emissions that cause haze. 

An easily understood measure of visibility to most people is visual range. Visual range is the 

greatest distance, in kilometers or miles, at which a dark object can be viewed against the sky. 
Regional Haze SIP 8 

for North Carolina Class I Areas December 17, 2007 

For evaluating the relative contributions of pollutants to visibility impairment, however, the most 

useful measure of visibility impairment is light extinction, which is usually expressed in units of 

inverse megameters (Mm-1). Light extinction affects the clarity and color of objects being 

viewed. 

The measure used by the regional haze rule is the deciview (dv). Deciviews are calculated 

directly from light extinction using a logarithmic scale. The deciview is a useful measure for 

tracking progress in improving visibility, because each deciview change is an equal incremental 

change in visibility perceived by the human eye. Most people can detect a change in visibility at 

one deciview. 

For each Class I area, there are three metrics of visibility that are part of the determination of 

reasonable progress: 

1) natural conditions, 

2) baseline conditions, and 

3) current conditions. 

Each of the three metrics includes the concentration data of the visibility pollutants as different 

terms in the light extinction algorithm, with respective extinction coefficients and relative 

humidity factors. Total light extinction when converted to deciviews (dv) is calculated for the 

average of the 20% best and 20% worst visibility days. 

“Natural” visibility is determined by estimating the natural concentrations of visibility pollutants 

and then calculating total light extinction. “Baseline” visibility is the starting point for the 

improvement of visibility conditions. It is the average of the Interagency Monitoring of 

Protected Visual Environments (IMPROVE) monitoring data for 2000 through 2004 and is 

equivalent to “current” visibility conditions for this initial review period. The comparison of 

initial baseline conditions to natural visibility conditions indicates the amount of improvement 

necessary to attain natural visibility by 2064. Each state must estimate natural visibility levels 

for Class I areas within its borders in consultation with FLMs and other states (40 CFR 

51.308(d)(2)). “Current conditions” are assessed every five years as part of the SIP review 

where actual progress in reducing visibility impairment is compared to the reductions committed 

to in the SIP. 

2.1 Estimating Natural Conditions for North Carolina Class I Areas 

Natural background visibility, as defined in Guidance for Estimating Natural Visibility 

Conditions Under the Regional Haze Program, EPA-454/B-03-005, September 2003, is based on 

annual average concentrations of fine particle components. The same annual average natural 

background visibility is assumed for all Class I areas in the eastern United States (separate values 

are estimated for the western United States). Natural background visibility for the 20% worst 

days is estimated by assuming that fine particle concentrations for natural background are 

normally distributed and the 90th percentile of the annual distribution represents natural 

background visibility on the 20% worst days. 
Regional Haze SIP 9 

for North Carolina Class I Areas December 17, 2007 

In the 2003 guidance, the USEPA also provided that states may use a “refined approach” to 

estimate the values that characterize the natural visibility conditions of the Class I areas. The 

purpose of such a refinement would be to provide more accurate estimates with changes to the 

extinction algorithm that may include the concentration values, factors to calculate extinction 

from a measured particular species and particle size, the extinction coefficients for certain 

compounds, geographical variation (by altitude) of a fixed value, and the addition of visibility 

pollutants. 

In 2005, the IMPROVE Steering Committee made recommendations for a refined equation that 

modifies the terms of the original equation to account for the most recent data. The choice 

between use of the old or the new equation for calculating the visibility metrics for each Class I 

area is made by the state in which the Class I area is located. 

The new IMPROVE equation accounts for the effect of particle size distribution on light 

extinction efficiency of sulfate, nitrate, and organic carbon. The mass multiplier for organic 

carbon (particulate organic matter) is increased from 1.4 to 1.8. New terms are added to the 

equation to account for light extinction by sea salt and light absorption by gaseous nitrogen 

dioxide. Site-specific values are used for Rayleigh scattering to account for the site-specific 

effects of elevation and temperature. Separate relative humidity enhancement factors are used 

for small and large size distributions of ammonium sulfate and ammonium nitrate and for sea 

salt. The elemental carbon (light-absorbing carbon), fine soil, and coarse mass terms do not 

change between the original and new IMPROVE equation. 

Natural background conditions using the new IMPROVE equation are calculated separately for 

each Class I area. The calculation starts with the annual average values for natural background 

for each component of PM2.5 mass from the EPA 2003 guidance (default values). The annual 

frequency distribution of values of each PM2.5 component for current conditions (2000-2004) is 

then defined. This species-specific frequency distribution is applied to the default annual 

average values for that PM2.5 component to calculate natural conditions on the 20% worst days. 

The current variability in each component is retained while also retaining the same annual 

average background condition for that component as defined in the 2003 guidance. The new 

calculation of natural background allows Rayleigh scattering to vary with elevation. Current sea 

salt values are used for natural background levels of sea salt. 

The VISTAS states chose to use the new IMPROVE equation as the basis for the conceptual 

description because it takes into account the most recent review of the science and because it is 

recommended by the IMPROVE Steering Committee. For more detailed discussion of the two 

IMPROVE equations, see Appendix B. 

2.2 Estimating Baseline Conditions for North Carolina Class I Areas 

Baseline visibility conditions at each North Carolina Class I area are estimated using sampling 

data collected at IMPROVE monitoring sites at four of the five Class I areas in North Carolina. 

A five-year average (2000 to 2004) was calculated for each of the 20% worst and 20% best 

visibility days in accordance with 40 CFR 51.308(d)(2) and Guidance for Tracking Progress 

Under the Regional Haze Rule, EPA-454-03-004, September, 2003. IMPROVE data records for 
Regional Haze SIP 10 

for North Carolina Class I Areas December 17, 2007 

Great Smoky Mountains and Linville Gorge for the period 2000 to 2004 meet the USEPA 

requirements for data completeness (75 percent for the year and 50 percent for each quarter). 

Shining Rock and Swanquarter had missing data in more than one year between 2000 to 2004. 

Data records for these sites were filled using data substitution procedures outlined in Appendix 

B. IMPROVE does not operate a monitor at Joyce Kilmer Wilderness and considers the 

IMPROVE monitor at Great Smoky Mountains to be representative of visibility in the Joyce 

Kilmer area. The light extinction and deciview visibility values for the 20% worst and 20% best 

visibility days at the Class I areas are based on data and calculations included in Appendix B of 

this SIP. 

2.3 Summary of Natural Background and Baseline Conditions for North Carolina Class I 

Areas 

Table 2.3-1 presents estimated natural background and baseline visibility metrics for North 

Carolina Class I areas. Note that North Carolina is not considering international emissions to be 

a component of natural background. Baseline visibility on the 20% worst days at the southern 

Appalachian Class I area monitoring sites, including Great Smoky Mountains, Linville Gorge, 

and Shining Rock, is generally between 28 and 30 dv, and baseline visibility at Swanquarter is 

25 dv. Natural background visibility at all four sites is predicted to be between 11 and 12 dv. 

The Class I area with the worst visibility impairment is Great Smoky Mountains, at greater than 

30 dv on the 20% worst days. Swanquarter experiences somewhat less visibility impairment on 

the 20% worst days than the mountain monitoring sites. 

Table 2.3-1 Natural Background and Baseline Conditions for North Carolina Class I Areas

Class 1 area 

Average for 

20% Worst 

Days 

(deciviews) 

Average for 

20% Best 

Days 

(deciviews) 

Average for 

20% Worst 

Days 

Bext (Mm-1) 

Average for 

20% Best 

Days 

Bext (Mm-1) 

Natural Background Conditions 

Great Smoky Mountains 11.1 4.5 30.8 15.8 

Joyce Kilmer-Slickrock 11.1 4.5 30.8 15.8 

Linville Gorge 11.2 4.1 30.9 15.1 

Shining Rock 11.5 2.5 34.9 12.1 

Swanquarter 11.5 5.5 32.6 17.3 

Baseline Visibility Conditions (2000 – 2004) 

Great Smoky Mountains 30.3 13.6 216.3 40.2 

Joyce Kilmer-Slickrock 30.3 13.6 216.3 40.2 

Linville Gorge 28.8 11.1 183.6 31.2 

Shining Rock 28.5 7.7 182.2 22.3 

Swanquarter 24.7 12.0 123.9 33.7 
Regional Haze SIP 11 

for North Carolina Class I Areas December 17, 2007 

2.4 Pollutant Contributions to Visibility Impairment (2000-2004 Baseline Data) 

The 20% worst visibility days at the Southern Appalachian sites (in North Carolina: Great 

Smoky Mountains, Joyce Kilmer, Linville Gorge, and Shining Rock) generally occur in the 

period April to September, with sulfate being the largest component. To illustrate this, 

Figure 2.4-1 displays the 2000 – 2004 reconstructed extinction, using the new IMPROVE 

equation, for the 20% worst days for the Great Smoky Mountains National Park. Similar plots 

for the other North Carolina Class I areas can be found in Appendix B. The peak hazy days 

occur in the summer under stagnant weather conditions with high relative humidity, high 

temperatures, and low wind speeds. The 20% best visibility days at the Southern Appalachian 

sites can occur at any time of year. At Swanquarter and other coastal sites, the 20% worst and 

best visibility days are distributed throughout the year. Figures 2.4-2 and 2.4-3 displays the 

average light extinction for the 20% haziest days and 20% clearest days, respectively. 

Figure 2.4-1. The 2000 – 2004 reconstructed extinction, using the new IMPROVE 

equation, for the 20% worst days at the Great Smoky Mountains National Park. 

0

50

100

150

200

250

300

350

3/8 5/17 6/3 6/10 6/28 7/1 7/8 7/22 8/5 8/16 8/19 8/23 8/26 10/15 10/18 10/21 10/24 10/27 11/2 12/11 5/1 5/7 6/9 6/12 6/21 6/27 7/3 7/12 7/18 7/21 7/24 7/30 8/2 8/5 8/8 8/11 8/14 8/17 8/23 8/26 9/7 9/13 9/19 11/18 2/25 5/2 5/8 5/17 6/1 6/13 6/19 6/22 7/1 7/7 7/10 7/16 7/31 8/3 8/6 8/9 8/12 8/15 8/21 9/5 9/8 9/11 9/17 9/23 3/16 4/27 5/24 5/27 6/5 6/11 6/20 6/26 6/29 7/5 7/17 7/20 7/26 8/7 8/10 8/16 8/19 8/22 8/25 8/28 9/3 9/6 9/12 9/21 1/10 2/21 6/8 6/11 6/20 6/26 6/29 7/8 7/17 7/20 7/29 8/4 8/10 8/16 8/19 8/25 8/28 8/31 9/3 9/12 9/15 9/30 10/3 10/30

2000 2001 2002 2003 2004

Extinction (Mm-1)

ECM

ESoil

ELAC

EOMC

EAmm_NO3

EAmm_SO4

Rayleigh

0

50

100

150

200

250

300

350

3/8 5/17 6/3 6/10 6/28 7/1 7/8 7/22 8/5 8/16 8/19 8/23 8/26 10/15 10/18 10/21 10/24 10/27 11/2 12/11 5/1 5/7 6/9 6/12 6/21 6/27 7/3 7/12 7/18 7/21 7/24 7/30 8/2 8/5 8/8 8/11 8/14 8/17 8/23 8/26 9/7 9/13 9/19 11/18 2/25 5/2 5/8 5/17 6/1 6/13 6/19 6/22 7/1 7/7 7/10 7/16 7/31 8/3 8/6 8/9 8/12 8/15 8/21 9/5 9/8 9/11 9/17 9/23 3/16 4/27 5/24 5/27 6/5 6/11 6/20 6/26 6/29 7/5 7/17 7/20 7/26 8/7 8/10 8/16 8/19 8/22 8/25 8/28 9/3 9/6 9/12 9/21 1/10 2/21 6/8 6/11 6/20 6/26 6/29 7/8 7/17 7/20 7/29 8/4 8/10 8/16 8/19 8/25 8/28 8/31 9/3 9/12 9/15 9/30 10/3 10/30

2000 2001 2002 2003 2004

Extinction (Mm-1)

ECM

ESoil

ELAC

EOMC

EAmm_NO3

EAmm_SO4

Rayleigh
Regional Haze SIP 12 

for North Carolina Class I Areas December 17, 2007 

Figure 2.4-2. Average light extinction for the 20% Haziest Days in 2000-2004 at VISTAS 

and neighboring Class I areas using new IMPROVE equation 

Figure 2.4-3. Average light extinction for the 20% Clearest Days in 2000-2004 at VISTAS 

and neighboring Class I areas using new IMPROVE equation 

VISTAS coastal VISTAS inland Neighboring non-VISTAS

0

50

100

150

200

250

300

Swanquarter, NC

Cape Romain, SC

Okefenokee, GA

Everglades, FL

Chassahowitzka, FL

St. Marks, FL

Dolly Sods, WV

Shenandoah, VA

James River Face, VA

Linville Gorge, NC

Shining Rock, NC

Great Smoky Mtns., TN

Cohutta, GA

Sipsey, AL

Mammoth Cave, KY

Brigantine, NJ

Breton, LAMingo, MO

Hercules Glades, MO

Upper Buffalo, AR

Caney Creek, AR

Extinction (Mm -1)

Sea Salt

Coarse

Soil

EC

POM

NH4NO3

(NH4)2SO4

Rayleigh

g

VISTAS coastal VISTAS inland Neighboring non-VISTAS

0

50

100

150

200

250

300

Swanquarter, NC

Cape Romain, SC

Okefenokee, GA

Everglades, FL

Chassahowitzka, FL

St. Marks, FL

Dolly Sods, WV

Shenandoah, VA

James River Face, VA

Linville Gorge, NC

Shining Rock, NC

Great Smoky Mtns., TN

Cohutta, GA

Sipsey, AL

Mammoth Cave, KY

Brigantine, NJ

Breton, LAMingo, MO

Hercules Glades, MO

Upper Buffalo, AR

Caney Creek, AR

Extinction (Mm -1)

Sea Salt

Coarse

Soil

EC

POM

NH4NO3

(NH4)2SO4

Rayleigh

g

0

10

20

30

40

50

60

Extinction (Mm-1)

Sea Salt

CM

Soil

EC

POM

NH4NO3

(NH4)2SO4

Rayleigh

VISTAS coastal VISTAS inland Neighboring non-VISTAS

Swanquarter, NC

Cape Romain, SC

Okefenokee, GA

Everglades, FL

Chassahowitzka, FL

St. Marks, FL

Dolly Sods, WV

Shenandoah, VA

James River Face, VA

Linville Gorge, NC

Shining Rock, NC

Great Smoky Mtns., TN

Cohutta, GA

Sipsey, AL

Mammoth Cave, KY

Brigantine, NJ

Breton, LA

Mingo, MO

Hercules Glades, MO

Upper Buffalo, AR

Caney Creek, AR

0

10

20

30

40

50

60

Extinction (Mm-1)

Sea Salt

CM

Soil

EC

POM

NH4NO3

(NH4)2SO4

Rayleigh

VISTAS coastal VISTAS inland Neighboring non-VISTAS

Swanquarter, NC

Cape Romain, SC

Okefenokee, GA

Everglades, FL

Chassahowitzka, FL

St. Marks, FL

Dolly Sods, WV

Shenandoah, VA

James River Face, VA

Linville Gorge, NC

Shining Rock, NC

Great Smoky Mtns., TN

Cohutta, GA

Sipsey, AL

Mammoth Cave, KY

Brigantine, NJ

Breton, LA

Mingo, MO

Hercules Glades, MO

Upper Buffalo, AR

Caney Creek, AR

g
Regional Haze SIP 13 

for North Carolina Class I Areas December 17, 2007 

Ammonium sulfate, (NH4)2SO4, is the most important contributor to visibility impairment and 

fine particle mass on the 20% worst and 20% best visibility days at all the North Carolina Class I 

areas. Sulfate levels on the 20% worst days account for 60-70 percent of the visibility 

impairment. Across the VISTAS region, sulfate levels are higher at the Southern Appalachian 

sites than at the coastal sites (Figure 2.4-1). On the 20% clearest days, sulfate levels are more 

uniform across the region (Figure 2.4-2). [Note that in these two figures, levels at Great Smoky 

Mountains National Park should be considered to be representative of levels at Joyce KilmerSlickrock Wilderness.] 

The best average visibility and lowest sulfate values on the clearest days occurred at Shining 

Rock. Shining Rock, at 1621 meters elevation, is likely influenced on the clearest days by 

regional transport of air masses above the boundary layer. Sulfate particles are formed in the 

atmosphere from SO2 emissions. Sulfate particles occur as hydrogen sulfate, H2(SO4), 

ammonium bisulfate HNH4SO4, and ammonium sulfate, (NH4)2SO4, depending on the 

availability of ammonia, NH3, in the atmosphere. 

Particulate Organic Matter (POM) is the second most important contributor to fine particle mass 

and light extinction on the 20% haziest and the 20% clearest days at the North Carolina Class I 

areas. Elevated levels of POM and Elemental Carbon, EC, indicate impact from wildfires or 

prescribed fire. Significant fire impacts are infrequent at Class I areas in North Carolina. 

VISTAS collected additional samples of carbon at five sites, including Great Smoky Mountains 

and Millbrook located in Raleigh, North Carolina, to better understand sources contributing to 

carbon in rural and urban areas. Samples were analyzed to define the amount of carbon-14 

isotope as an indicator of the amount of carbon from modern sources (vegetative emissions, 

fires) and the amount of carbon from fossil sources (gasoline, diesel, oil). For most samples, the 

ratio of modern carbon to fossil carbon was greater than 0.60 throughout the year. In the fall, 

winter, and spring, more of the modern carbon is attributable to wood burning while in the 

summer months more of the modern carbon mass is attributable to biogenic emissions from 

vegetation. On some days greater than 90% of the carbon at Great Smoky Mountains is 

attributable to modern sources of carbon. Biogenic carbon emissions at Cape Romain, South 

Carolina, a coastal site similar to Swanquarter, were lower than emissions at the forested 

mountain sites. Carbon from gasoline and diesel engines is a relatively small contribution at the 

rural sites. At Millbrook, carbon from fossil fuel combustion is a larger percentage contribution 

than at the rural sites, but still less than 50% of total carbon measured. These results suggest that 

controlling anthropogenic sources of carbon will have little benefit in improving visibility in 

Class I areas since the majority of the POM comes from natural, i.e., biogenic, sources. 

Controlling anthropogenic sources of carbon will likely be more effective to reduce levels of 

PM2.5 in urban areas. 

Ammonium nitrate, NH4NO3, is formed in the atmosphere by reaction of NH3 and NOx. In the 

VISTAS region, nitrate formation is limited by availability of NH3 and by temperature. 

Ammonia preferentially reacts with SO2 and sulfate before reacting with NOx. Particle nitrate is 

formed at lower temperatures; at elevated temperatures nitric acid remains in gaseous form. For 

this reason, particle nitrate levels are very low in the summer and a minor contributor to visibility 

impairment. Particle nitrate concentrations are higher on winter days and are more important for 

the coastal sites where 20% worst days can occur on winter days. Nitrogen oxides are emitted by 
Regional Haze SIP 14 

for North Carolina Class I Areas December 17, 2007 

fossil fuel combustion by point, area, on-road, and off-road mobile sources. Modeling data (see 

Section 7) indicate that in the VISTAS region ammonium nitrate formation is limited by NH3 

concentrations and suggest that for winter days, controls of NH3 sources would be more 

effective in reducing ammonium nitrate levels than controls of NOx. 

Elemental Carbon, EC, is a comparatively minor contributor to visibility impairment. Sources 

include agriculture, prescribed, wildland, and wild fires and incomplete combustion of fossil 

fuels. EC levels are higher at urban monitors than at the Class I areas and suggest controls of 

fossil fuel combustion sources would be more effective to reduce PM2.5 in urban areas than to 

improve visibility in Class I areas. 

Soil fine particles are minor contributors to visibility impairment at most southeastern sites on 

most days. Occasional episodes of elevated fine soil can be attributed to Saharan dust episodes, 

particularly at Everglades, Florida, but rarely are seen at the North Carolina Class I areas. No 

control strategies are indicated for fine soil. 

Sea salt, NaCl, is observed at the coastal sites. Sea salt contributions to visibility impairment are 

most important on the 20% clearest days when sulfate and POM levels are low. Sea salt levels 

do not contribute significantly to visibility on the 20% worst visibility days. The new 

IMPROVE equation uses Chloride ion, Cl-

, from routine IMPROVE measurements to calculate 

sea salt levels. VISTAS used Cl-

 to calculate sea salt contributions to visibility following 

IMPROVE guidance. 

Coarse particle mass (particles with diameters between 2.5 and 10 microns) has a relatively 

small contribution to visibility impairment because the light extinction efficiency of coarse mass 

is very low compared to the extinction efficiency for sulfate, nitrate, and carbon. 

An unidentified component is reported by IMPROVE as the difference between the total PM2.5 

mass measured on the filter and the sum of the measured components. This unidentified mass 

may be positive or negative and is attributable to water and/or the factors used to calculate 

molecular weights of the other components. 

 

The new IMPROVE equation generally results in higher calculated light extinction on days with 

higher mass and lower light extinction on days with lower mass. This tends to increase 

calculated light extinction for current conditions and to decrease calculated light extinction for 

natural visibility conditions. Adding sea salt to the new IMPROVE equation increases light 

extinction for both current and natural visibility conditions. Increasing the mass multiplier for 

POM in the new IMPROVE equation increases light extinction for current conditions more than 

for natural conditions. The new algorithm does not change the conclusion that in the VISTAS 

region, and in North Carolina, the most effective means to improve visibility is to reduce sulfate 

concentrations. 

PM2.5 trends in urban and Class I areas: IMPROVE data were compared to monitoring data 

from the Speciated Trends Network (STN) in nearby urban areas to understand the similarities 

and differences in composition of fine particle mass. Several PM2.5 nonattainment areas are in 

close proximity to the Class I areas in the southeastern United States, including Atlanta, GA; 
Regional Haze SIP 15 

for North Carolina Class I Areas December 17, 2007 

Birmingham, AL; Charleston, WV; Chattanooga, TN; Knoxville, TN; and Louisville, KY. 

Ammonium sulfate concentrations are comparable between urban and nearby Class I areas, 

while organic carbon, elemental carbon, and nitrate concentration are generally higher in urban 

areas than the Class I areas. These results suggest that sulfate is widely distributed regionally 

while urban areas see an additional incremental pollutant loading from local emissions sources. 

Role of meteorology in determining visibility conditions: Classification and Regression Tree 

(CART) Analyses were used to characterize the relationship between meteorological conditions 

and visibility conditions at the Class I areas. Days were assigned to one of five visibility classes 

ranging from poor to good visibility. Days were then assigned to bins based on meteorological 

conditions. For the North Carolina Class I areas, poor visibility days were most likely to occur 

on days with high temperatures, high relative humidity, low wind speeds, and elevated PM2.5 

mass at upwind urban areas. Precipitation was not a good predictor of visibility condition. 

Weights were assigned to days based on frequency of occurrence of days with similar 

meteorological conditions. 

The above analyses are further discussed in Appendix B. 

3.0 GLIDEPATHS TO NATURAL CONDITIONS IN 2064 

As stated in Section 1.3, the regional haze rule directs states to graphically show what would be a 

“uniform rate of progress” toward natural conditions for each mandatory Class I Federal area 

within the State as well as for each mandatory Class I Federal area located outside the State, 

which may be affected by emissions from sources within the State. The uniform rate of progress 

is also known as the “glidepath.” The glidepath is simply a straight graphical line drawn from 

the baseline level of visibility impairment for 2000-2004 to the level representing no manmade 

impairment in 2064. 

Each state must set goals for each Class I area that provide for reasonable progress towards 

achieving natural visibility conditions by 2064. Section 51.308(d)(1) of the regional haze rule 

requires that reasonable progress goals must both: 

(1) provide for improvement in visibility for the most impaired days over the period of the 

implementation plan; and 

(2) ensure no degradation in visibility for the least impaired days over the same period. 

Uniform rate of progress graphs (glidepaths), were developed for each Class I area in the 

VISTAS region. The glidepaths were developed in accordance with the USEPA’s guidance for 

tracking progress and used data collected from the IMPROVE monitoring sites as described in 

Section 2 of this document. The glidepath is one of the indicators used in setting reasonable 

progress goals. 
Regional Haze SIP 16 

for North Carolina Class I Areas December 17, 2007 

3.1 Glidepaths for Class I Areas in North Carolina 

The following are glidepaths for the 20% most impaired days for Great Smoky Mountains 

National Park, Joyce Kilmer-Slickrock Wilderness Area, Linville Gorge Wilderness Area, 

Shining Rock Wilderness Area, and Swanquarter Wildlife Refuge, assuming uniform rate of 

progress toward regional haze goals. Natural background visibility at all four sites is predicted to 

be between 11 and 12 dv. The Class I areas with the steepest slope from baseline to natural 

background conditions are Great Smoky Mountains and Joyce Kilmer-Slickrock, while 

Swanquarter currently has the shortest path from the baseline level of visibility impairment to 

natural conditions. 

Figure 3.1-1. Uniform Rate of Progress Glidepath for 20% worst days at Great Smoky 

Mountains National Park. 

Uniform Rate of Reasonable Progress Glide Path

Great Smoky Mountains - 20% Worst Days

New IMPROVE Equation

30.28

28.67

25.79

22.59

19.38

16.18

12.97

11.05

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews) . 

Glide Path Natural Condition (Worst Days) Observation
Regional Haze SIP 17 

for North Carolina Class I Areas December 17, 2007 

Figure 3.1-2. Uniform Rate of Progress Glidepath for 20% worst days at Joyce KilmerSlickrock Wilderness Area. 

Figure 3.1-3. Uniform Rate of Progress Glidepath for 20% worst days at Linville Gorge 

Wilderness Area. 

Uniform Rate of Reasonable Progress Glide Path

Linville Gorge - 20% Worst Days

New IMPROVE Equation

28.77

27.31

24.67

21.74

18.81

15.88

12.95

11.19

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews) .

Glide Path Natural Condition (Worst Days) Observation

Uniform Rate of Reasonable Progress Glide Path

Joyce Kilmer - Slickrock - 20% Worst Days

New IMPROVE Equation

30.28

28.67

25.79

22.59

19.38

16.18

12.97

11.05

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews) . 

Glide Path Natural Condition (Worst Days) Observation
Regional Haze SIP 18 

for North Carolina Class I Areas December 17, 2007 

Figure 3.1-4. Uniform Rate of Progress Glidepath for 20% worst days at Shining Rock 

Wilderness Area. 

Figure 3.1-5. Uniform Rate of Progress Glidepath for 20% worst days at Swanquarter 

Wildlife Refuge. 

Uniform Rate of Reasonable Progress Glide Path

Swanquarter - 20% Worst Days

New IMPROVE Equation

24.74 23.64

21.66

19.46

17.26

15.07

12.87

11.55

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews) .

Glide Path Natural Condition (Worst Days) Observation

Uniform Rate of Reasonable Progress Glide Path

Shining Rock - 20% Worst Days

New IMPROVE Equation

28.46

27.04

24.50

21.66

18.83

16.00

13.17

11.47

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews) 

Glide Path Natural Condition (Worst Days) Observation
Regional Haze SIP 19 

for North Carolina Class I Areas December 17, 2007 

4.0 TYPES OF EMISSIONS IMPACTING VISIBILITY IMPAIRMENT IN 

NORTH CAROLINA CLASS I AREAS

4.1 Baseline Emissions Inventory 

The regional haze rule at 51.308(d)(4)(v) requires a statewide emissions inventory of pollutants 

that are reasonably anticipated to cause or contribute to visibility impairment in any mandatory 

Class I area. An inventory was developed for the baseline year 2002 and projected to 2009 and 

2018. The pollutants inventoried include VOCs, NOx, PM2.5, coarse particulate (PM10), NH3 

and SO2. The baseline emissions inventory for 2002 was developed for North Carolina 

following the methods described in Appendix D. 

There are five different emission inventory source classifications: stationary point and area 

sources, off-road and on-road mobile sources, and biogenic sources. Stationary point sources are 

those sources that emit greater than a specified tonnage per year, with data provided at the 

facility level. Electric generating utilities and industrial sources are the major categories for 

stationary point sources. Stationary area sources are those sources whose individual emissions 

are relatively small, but due to the large number of these sources, the collective emissions from 

the source category could be significant (i.e., dry cleaners, service stations, agricultural sources, 

fire emissions, etc.). These types of emissions are estimated on a countywide level. Off-road (or 

non-road) 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 these 

sources, like stationary area sources, are estimated on a countywide level. On-road mobile 

sources are automobiles, trucks, and motorcycles that use the roadway system. The emissions 

from these sources are estimated by vehicle type and road type and are summed to the 

countywide level. Biogenic sources are the natural sources like trees, crops, grasses and natural 

decay of plants. The emissions from these sources are estimated on a countywide level. 

In addition to the various source classifications, there are also various types of emission 

inventories. The first is the actual base year inventory. This inventory is the base year emissions 

that correspond to the meteorological data used, which for this modeling effort is data from 

2002. These emissions are used for evaluating the air quality model performance. 

The second type of inventory is the typical base year inventory. This inventory is similar to the 

actual base year inventory, except that for sources whose emissions change significantly from 

year to year, a more typical emission value is used. In this modeling effort, typical emissions 

were developed for the electric generating units (EGUs) and the wildland fire emissions. The air 

quality modeling is run using the typical base year inventory and the future year inventory. The 

results from these two runs are then used to calculate relative reduction factors. These relative 

reduction factors are used to estimate the future year visibility estimates that are used to 

demonstrate reasonable progress toward visibility goals. 

Below is an overview of the inventories used for each source classification. More detailed 

discussion of the emissions inventory development is contained in Appendix D. 
Regional Haze SIP 20 

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4.1.1 Stationary Point Sources 

Point source emissions are emissions from individual sources having a fixed location. Generally, 

these sources must have permits to operate, and their emissions are inventoried on a regular 

schedule. Large sources emitting at least 100 tons per year (tpy) of a criteria pollutant, 10 tpy of 

a single hazardous air pollutant (HAP), or 25 tpy total HAP are inventoried annually. Smaller 

sources have been inventoried less frequently. The point source emissions data can be grouped 

as EGU sources and other industrial point sources, also called non-EGUs. 

Electric Generating Units

The actual base year inventory for the EGU sources used 2002 continuous emissions monitoring 

(CEM) data reported to the USEPA’s Acid Rain program or 2002 hourly emissions data 

provided by stakeholders. These data provide hourly emissions profiles for SO2 and NOx that 

can be used in air quality modeling. Emissions profiles are used to estimate emissions of other 

pollutants (VOCs, carbon monoxide, NH3, PM2.5) based on measured emissions of SO2 and 

NOx. 

Emissions from EGU vary daily and seasonally as a function of variability in energy demand and 

utilization and outage schedules. To avoid anomalies in future year emissions created by relying 

on 2002 operations to represent future operations, a typical base year emissions inventory was 

developed for EGUs. This approach is consistent with the USEPA’s 2007 modeling guidance. 

To develop a typical year 2002 emissions inventory for EGU sources, each unit’s average CEM 

heat input for 2000 through 2004 was divided by the 2002 actual heat input to generate a unit 

specific normalizing factor. This normalizing factor was then multiplied by the 2002 actual 

emissions. The heat inputs for the period 2000 through 2004 were used because the modeling 

current conditions use monitored data from this same 5-year period. If a unit was shut down for 

an entire year during the 2000 through 2004 period, the average of the years the unit was 

operational was used. If a unit was shut down in 2002, but not permanently shutdown, the 

emissions and heat inputs from 2001 (or 2000) were used in the normalizing calculations. 

As part of the VISTAS air quality modeling, VISTAS, in cooperation with the other eastern 

RPOs, contracted with ICF Resources, L.L.C., to generate future year emission inventories for 

the electric generating sector of the contiguous United States using the Integrated Planning 

Model (IPM) version 2.1.9 updated with state-specific information. IPM is a dynamic linear 

optimization model that can be used to examine air pollution control policies for various 

pollutants throughout the contiguous United States for the entire electric power system. The 

dynamic nature of IPM enables projection of the behavior of the power system over a specified 

future period. Optimization logic in IPM determines the least-cost means of meeting electric 

generation and capacity requirements while complying with specified constraints including air 

pollution regulations, transmission bottlenecks, and plant-specific operational constraints. The 

versatility of IPM allows users to specify which constraints to exercise, and to populate IPM with 

their own datasets. 

The IPM modeling runs took into consideration both CAIR implementation and North Carolina’s 

CSA requirements for Duke Energy and Progress Energy. 

 
Regional Haze SIP 21 

for North Carolina Class I Areas December 17, 2007 

Other Industrial Point Sources

For the non-EGU sources, the same inventory is used for both the actual and typical base year 

emissions inventories. The non-EGU category uses annual emissions as reported under the 

Consolidated Emissions Reporting Rule (CERR) for the year 2002. These emissions are 

temporally allocated to month, day, and hour using source category code (SCC)-based allocation 

factors. 

The general approach for assembling future year data was to use recently updated growth and 

control data consistent with the USEPA’s CAIR analyses. This data was supplemented with 

state-specific growth factors and stakeholder input on growth assumptions. 

4.1.2 Stationary Area Sources 

Stationary area sources are sources whose individual emissions are relatively small, but due to 

the large number of these sources, the collective emissions could be significant (i.e., combustion 

of fuels for heating, structure fires, service stations, etc.). Emissions are estimated by 

multiplying an emission factor by some known indicator of collective activity, such as fuel 

usage, number of households, or population. Stationary area source emissions are estimated at 

the countywide level. 

A portion of the area source 2002 base year inventory for North Carolina was developed by the 

NCDAQ and provided to the VISTAS contractor. The VISTAS contractor calculated the 

remaining portion of the area source inventory. The sources estimated by the contractor include 

emissions from animal husbandry, wildland fires, and particulate matter from paved and unpaved 

roads. For the other states within the modeling domain, either state-supplied data or data 

reported under CERR for 2002 was used. 

The actual base year inventory will serve as the typical base year inventory for all area source 

categories except for wildland fires. For wildland fires, a typical year inventory was used to 

avoid anomalies in wildfire activity in 2002 compared to longer term averages. Development of 

a typical year wildfire inventory provided the capability of using a comparable data set for both 

the base year and future years. Thus, fire emissions remain the same for air quality modeling in 

both the base and any future years. The VISTAS Fire Special Interest Work Group used State 

records to ratio the number of acres burned over a longer term period (three or more years, as 

available from state records) to 2002. Based on these ratios, the 2002 acreage was then scaled up 

or down to develop a typical year inventory. 

The VISTAS contractor generated future year emissions inventories for 2009 and 2018 for the 

regional haze modeling. Growth factors, supplied either by states or taken from the CAIR 

emission projections, were applied to project the controlled emissions. If no growth factor was 

available from either the state or the CAIR growth factor files, then the USEPA’s Economic 

Growth and Analysis System Version 5 growth factors were used. 
Regional Haze SIP 22 

for North Carolina Class I Areas December 17, 2007 

4.1.3 Off-Road Mobile Sources 

Off-road mobile sources are equipment that can move but do not use the roadways, such as 

construction equipment, aircraft, railroad locomotives, lawn and garden equipment, etc. For the 

majority of the off-road mobile sources, the emissions for 2002 were estimated using the 

USEPA’s NONROAD2005c model. For the three source categories not included in the 

NONROAD model, i.e., aircraft engines, railroad locomotives and commercial marine, more 

traditional methods of estimating the emissions were used. The same inventory is used for both 

the actual and typical base year emissions inventories. 

For the source categories estimated using the USEPA’s NONROAD model, the model growth 

assumptions were used to create the 2009 and 2018 future year inventories. The NONROAD 

model takes into consideration regulations affecting emissions from these source categories. For 

the four largest airports in North Carolina, the Federal Aviation Administration’s Terminal Area 

Forecast was used to project growth in aircraft emissions. For the commercial marine, railroad 

locomotives and the remaining airport emissions, the VISTAS contractor calculated the future 

growth in emissions using detailed inventory data (both before and after controls) for 1996 and 

2010, obtained from the CAIR Technical Support Document. When available, state-specific 

growth factors were used. 

4.1.4 Highway Mobile Sources 

For on-road vehicles, the newest version of the MOBILE model, MOBILE6.2, was used. Key 

inputs for MOBILE include information on the age of vehicles on the roads, the average speeds 

on the roads, the mix of vehicles on the roads, any programs in place in an area to reduce 

emissions for motor vehicles (e.g., emissions inspection programs), and temperature. 

The MOBILE model takes into consideration regulations that affect emissions from this source 

sector. The same MOBILE run is used to represent the actual and typical year emissions for onroad vehicles using input data reflective of 2002. The MOBILE model then is run for 2018 

inventory using input data reflective of that year. The 2002 vehicle miles traveled (VMT), 

speeds, vehicle age and vehicle mix data were obtained from the North Carolina Department of 

Transportation (NCDOT). For urban areas in North Carolina that run travel demand models 

(TDMs), VMT and speed data from TDMs were used. 

4.1.5 Biogenic Emission Sources 

Biogenic emissions were prepared with the SMOKE-BEIS3 (Biogenic Emission Inventory 

System 3 version 0.9) preprocessor. SMOKE-BEIS3 is a modified version of the Urban Airshed 

Model (UAM)-BEIS3 model. Modifications include use of MM5 data, gridded land use data, 

and improved emissions characterization. The emission factors that are used in SMOKE-BEIS3 

are the same as the emission factors as in UAM-BEIS3. The basis for the gridded land use data 

used by BEIS3 is the county land use data in the Biogenic Emissions Landcover Database 

version 3 (BELD3) provided by the USEPA. A separate land classification scheme, based upon 

satellite (AVHRR, 1 km spatial resolution) and census information, aided in defining the forest, 

agriculture and urban portions of each county. 
Regional Haze SIP 23 

for North Carolina Class I Areas December 17, 2007 

4.1.6 Summary 2002 Baseline Emissions Inventory for North Carolina 

Table 4.1.6-1 is a summary of the 2002 baseline emission inventory for North Carolina. The 

complete inventory and discussion of the methodology is contained in Appendix D. The 

emissions summaries for other VISTAS states can also be found in Appendix D. 

Table 4.1.6-1 2002 Emissions Inventory Summary for North Carolina (tons/year) 

 VOC NOx PM2.5 PM10 NH3 SO2 

Point 61,484 196,731 26,953 36,539 1,233 522,093 

Area 250,044 41,517 83,520 300,838 162,183 5,815 

On-Road Mobile 263,766 327,329 4,623 6,579 9,702 12,420 

Off-Road Mobile 94,480 84,284 7,348 7,348 65 7,693 

Biogenics 1,213,819 17,888 0 0 0 0 

TOTAL 1,883,593 667,749 122,444 351,304 173,183 548,021 

4.1.7 Model Performance Improvements through Emissions Inventory Improvements 

Since the initial model performance evaluation, VISTAS has made several improvements to the 

emissions inventory, which in turn improved model performance. These inventory 

improvements are detailed in the VISTAS emissions inventory report and Appendix D, and are 

summarized here: 

• For electric generating utilities, the Integrated Planning Model (IPM) was used to provide 

estimates of future year utility production and emissions. Continuous Emissions 

Monitoring data was used to define seasonal variability in production and emissions. The 

states updated IPM model projections from with control data provided by utility 

companies in late 2006 through early 2007. 

• For on-road vehicle emissions, states and local agencies provided updated MOBILE 

model input and vehicle-miles-traveled data. 

• For ammonia emissions from agricultural sources, the Carnegie Mellon University 

ammonia model was used to improve annual and monthly estimates. 

• For fires, the VISTAS states provided fire activity data for 2002 for wildfires, prescribed 

fire, land clearing and agricultural burning to develop a 2002 fire inventory. Where data 

allowed, large fire events were modeled as point sources. In 2006, United States Forest 

Service and Fish and Wildlife Service provided projections of increased prescribed 

burning in 2009 and 2018; these data were incorporated in the inventory for all states 

except Florida. Because current prescribed fire activity already reflects the use of fire as 

a forest management technique, Florida believed that there is too much uncertainty to 

project how future total fire activity (prescribed plus wildfire) will change. In Florida, 

prescribed fire in the future years is the same as 2002 typical for prescribed fire. 

• For non-road engines, the updated USEPA NONROAD2005 emissions model was used. 

• For commercial marine emissions in shipping lanes in the Gulf of Mexico and Atlantic 

Oceans, gridded emissions for the VISTAS modeling domain was created using 

inventory data newly developed for the USEPA by Dr. Corbett at the University of 

Delaware. These emissions were incorporated in the modeling. 
Regional Haze SIP 24 

for North Carolina Class I Areas December 17, 2007 

• Updated inventories from the neighboring RPOs, Mexico, and Canada were incorporated 

as available. 

4.2 Assessment of Relative Contributions from Specific Pollutants and Sources Categories 

Ammonium sulfate is the largest contributor to visibility impairment at the North Carolina Class 

I areas, and reduction of SO2 emissions would be the most effective means of reducing 

ammonium sulfate. As illustrated in Figure 4.2-1, 96% of 2002 SO2 emissions in the VISTAS 

states are attributable to electric generating facilities and industrial point sources. Similarly, in 

North Carolina the stationary point sources, consisting of electric generating facilities and 

industrial point sources, contribute 95% of SO2 emissions in the State (see Table 4.2-1). 

Figure 4.2-1. 2002 SO2 emissions in the VISTAS States. 

Table 4.2-1 2002 SO2 Emissions for North Carolina (tons/year) 

 SO2 Percent 

Point 522,093 95.3% 

Area 5,815 1.1% 

On-Road Mobile 12,420 2.2% 

Off-Road Mobile 7,693 1.4% 

Biogenics 0 0% 

TOTAL 548,021 

Since the largest source of SO2 emissions comes from the stationary point sources, the focus of 

potential controls and the impacts for those controls was on this source sector. In North 

Carolina, the types of sources emitting SO2, and thus contributing to the visibility impairment of 

the Class I areas, were predominately coal fired utility and industrial boilers. 

VISTAS States SO2 Emissions - 2002 

Utilities

Industrial

On road

Non road

Other

Industrial: 20% Utilities: 76%

4.8 Million tons

VISTAS States SO2 Emissions - 2002 

Utilities

Industrial

On road

Non road

Other

Industrial: 20% Utilities: 76%

4.8 Million tons
Regional Haze SIP 25 

for North Carolina Class I Areas December 17, 2007 

5.0 REGIONAL HAZE MODELING METHODS AND INPUTS 

Modeling for regional haze was performed by VISTAS for the ten southeastern states, including 

North Carolina. The sections below outline the methods and inputs used by VISTAS for the 

regional modeling. Additional details are provided in Appendices C, D and M. 

5.1 Analysis Method 

The modeling analysis is a complex technical evaluation that begins by selection of the modeling 

system. VISTAS decided to use the following modeling system: 

• Meteorological Model: The Pennsylvania State University/National Center for 

Atmospheric Research (PSU/NCAR) Mesoscale Meteorological Model (MM5) is a 

nonhydrostatic, prognostic meteorological model routinely used for urban- and regionalscale photochemical, fine particulate matter, and regional haze regulatory modeling 

studies. 

• Emissions Model: The Sparse Matrix Operator Kernel Emissions (SMOKE) modeling 

system is an emissions modeling system that generates hourly gridded speciated emission 

inputs of mobile, nonroad mobile, area, point, fire and biogenic emission sources for 

photochemical grid models. 

• Air Quality Model: The USEPA’s Models-3/ Community Multiscale Air Quality 

(CMAQ) modeling system is an ‘One-Atmosphere’ photochemical grid model capable of 

addressing ozone, particulate matter (PM), visibility and acid deposition at regional scale. 

The USEPA’s 2007 modeling guidance recommends modeling an entire year or at a minimum 

several days in each quarter of a year to adequately represent the range of meteorological 

conditions that contribute to elevated levels of fine particulate matter. The year 2002 was 

selected by VISTAS as the modeling year for this demonstration. Meteorological inputs were 

developed for 2002 using the meteorological model. Emission inventories were also developed 

for 2002 and processed through the emissions model. These inputs were used in the air quality 

model to predict fine particle mass and visibility. The model results for 2002 were compared 

with observed meteorological and air quality data to evaluate model performance. Several 

configurations of the meteorological and air quality model were evaluated to select a 

configuration that gave the best overall performance for the VISTAS region. 

Once model performance was deemed adequate, the current and future year emissions were 

processed through the emissions model. The air quality modeling results are used to determine a 

relative reduction in future visibility impairment, which is used to determine reasonable progress. 

The complete modeling protocol used for this analysis can be found in Appendix C. 

5.2 Model Selection 

To ensure that a modeling study is defensible, care must be taken in the selection of the models 

to be used. The models selected must be scientifically appropriate for the intended application 

and be freely accessible to all stakeholders. Scientifically appropriate means that the models 
Regional Haze SIP 26 

for North Carolina Class I Areas December 17, 2007 

address important physical and chemical phenomena in sufficient detail, using peer-reviewed 

methods. Freely accessible means that model formulations and coding are freely available for 

review and that the models are available to stakeholders, and their consultants, for execution and 

verification at no or low cost. 

The following sections outline the criteria for selecting a modeling system that is both defensible 

and capable of meeting the study's goals. These criteria were used in selecting the modeling 

system used for this modeling demonstration. 

5.2.1 Selection of Photochemical Grid Model 

Criteria

For a photochemical grid model to qualify as a candidate for use in a regional haze SIP, a State 

needs to show that it meets the same several general criteria as a model for an attainment 

demonstration for a NAAQS: 

• The model has received a scientific peer review 

• The model can be demonstrated applicable to the problem on a theoretical basis 

• Data bases needed to perform the analysis are available and adequate 

• Available past appropriate performance evaluations have shown the model is not biased 

toward underestimates or overestimates 

• A protocol on methods and procedures to be followed has been established 

• The developer of the model must be willing to make the source code available to users 

for free or for a reasonable cost, and the model cannot otherwise be proprietary. 

Overview of CMAQ

The photochemical model selected for this study was CMAQ version 4.5. For more than a 

decade, the USEPA has been developing the Models-3 CMAQ modeling system with the 

overarching aim of producing a ‘One-Atmosphere’ air quality modeling system capable of 

addressing ozone, fine particulate matter, visibility and acid deposition within a common 

platform. The original justification for the Models-3 development emerged from the challenges 

posed by the 1990 CAAA and the USEPA’s desire to develop an advanced modeling framework 

for ‘holistic’ environmental modeling utilizing state-of-science representations of atmospheric 

processes in a high performance computing environment. The USEPA completed the initial 

stage of development with Models-3 and released the CMAQ model in mid-1999 as the initial 

operating science model under the Models-3 framework. The most recent rendition is CMAQ 

version 4.5, which was released in September 2005. 

An advantage of choosing CMAQ as the atmospheric model is the ability to do one-atmospheric 

modeling. The same model configuration is being applied for the ozone and PM2.5 attainment 

demonstrations SIPs, as well as the regional haze SIP. A number of features in CMAQ’s 
Regional Haze SIP 27 

for North Carolina Class I Areas December 17, 2007 

theoretical formulation and technical implementation make the model well suited for annual PM 

modeling. 

The configuration used for this modeling demonstration, as well as a more detailed description of 

the CMAQ model, can be found in the Modeling Protocol (Appendix C). 

5.2.2 Selection of Meteorological Model 

Criteria

Meteorological models, whether through objective, diagnostic, or prognostic analysis, extend 

available information about the state of the atmosphere to the grid upon which photochemical 

grid modeling is to be carried out. The criteria for selecting a meteorological model are based on 

both the models ability to accurately replicate important meteorological phenomena in the region 

of study, and the model’s ability to interface with the rest of the modeling systems -- particularly 

the photochemical grid model. With these issues in mind, the following criteria were established 

for the meteorological model to be used in this study: 

• Non-Hydrostatic Formulation 

• Reasonably current, peer reviewed formulation 

• Simulates Cloud Physics 

• Publicly available at no or low cost 

• Output available in I/O API format 

• Supports Four Dimensional Data Assimilation (FDDA) 

• Enhanced treatment of Planetary Boundary Layer heights for AQ modeling 

Overview of MM5

The non-hydrostatic MM5 model is a three-dimensional, limited-area, primitive equation, 

prognostic model that has been used widely in regional air quality model applications. The basic 

model has been under continuous development, improvement, testing and open peer-review for 

more than 20 years and has been used worldwide by hundreds of scientists for a variety of 

mesoscale studies. 

MM5 uses a terrain-following non-dimensionalized pressure, or "sigma", vertical coordinate 

similar to that used in many operational and research models. In the non-hydrostatic MM5, the 

sigma levels are defined according to the initial hydrostatically-balanced reference state so that 

the sigma levels are also time-invariant. The gridded meteorological fields produced by MM5 

are directly compatible with the input requirements of ‘one atmosphere’ air-quality models using 

this coordinate. MM5 fields can be easily used in other regional air quality models with different 

coordinate systems by performing a vertical interpolation, followed by a mass-conservation readjustment. 
Regional Haze SIP 28 

for North Carolina Class I Areas December 17, 2007 

Distinct planetary boundary layer parameterizations are available for air-quality applications, 

both of which represent sub-grid-scale turbulent fluxes of heat, moisture and momentum. One 

scheme uses a first-order eddy diffusivity formulation for stable and neutral environments and a 

modified first-order scheme for unstable regimes. The other scheme uses a prognostic equation 

for the second-order turbulent kinetic energy, while diagnosing the other key boundary layer 

terms. 

Initial and lateral boundary conditions are specified for real-data cases from mesoscale threedimensional analyses performed at 12-hour intervals on the outermost grid mesh selected by the 

user. Surface fields are analyzed at three-hour intervals. A Cressman-based technique is used to 

analyze standard surface and radiosonde observations, using the National Meteorological 

Center's spectral analysis, as a first guess. The lateral boundary data are introduced using a 

relaxation technique applied in the outermost five rows and columns of the coarsest grid domain. 

MM5 modeling system in regulatory air quality application studies have been widely reported in 

the literature (e.g., Emery et al., 1999; Tesche et al., 2000, 2003) and many have involved 

comparisons with other prognostic models such as the Regional Atmospheric Modeling System 

(RAMS) and the Systems Application International Mesoscale Model. The MM5 enjoys a far 

richer application history in regulatory modeling studies compared with RAMS or other models. 

Furthermore, in evaluations of these models in over 60 recent regional scale air quality 

application studies since 1995, it has generally been found that the MM5 model tends to produce 

somewhat better photochemical model inputs than alternative models. 

The configuration used for this modeling demonstration, as well as a more detailed description of 

the MM5 model, can be found in the meteorological modeling protocol (Appendix E). 

5.2.3 Selection of Emissions Processing System 

Criteria

The principal criterion for an emissions processing system is that it accurately prepares 

emissions files in a format suitable for the photochemical grid model being used. The following 

list includes clarification of this criterion and additional desirable criteria for effective use of the 

system. 

• File System Compatibility with the I/O API 

• File Portability 

• Ability to grid emissions on a Lambert Conformal projection 

• Report Capability 

• Graphical Analysis Capability 

• MOBILE6 Mobile Source Emissions 

• Biogenic Emissions Inventory System version 3 (BEIS-3) 

• Ability to process emissions for the proposed domain in a reasonable amount of time. 
Regional Haze SIP 29 

for North Carolina Class I Areas December 17, 2007 

• Ability to process control strategies 

• No or low cost for acquisition and maintenance 

• Expandable to support other species and mechanisms 

Overview of SMOKE

The SMOKE Emissions Processing System Prototype was originally developed at the Microcomputing Center of North Carolina. As with most ‘emissions models’, SMOKE is principally 

an emission processing system and not a true emissions modeling system in which emissions 

estimates are simulated from ‘first principles’. This means that, with the exception of mobile 

and biogenic sources, its purpose is to provide an efficient, modern tool for converting emissions 

inventory data into the formatted emission files required by an air quality simulation model. For 

mobile sources, SMOKE actually estimates emissions based on input mobile-source activity 

data, emission factors and outputs from transportation travel-demand models. 

 

SMOKE was originally designed to allow emissions data processing methods to utilize emergent 

high-performance-computing as applied to sparse-matrix algorithms. Indeed, SMOKE is the 

fastest emissions processing tool currently available to the air quality modeling community. The 

sparse matrix approach utilized throughout SMOKE permits both rapid and flexible processing 

of emissions data. The processing is rapid because SMOKE utilizes a series of matrix 

calculations instead of less efficient algorithms used in previous systems. The processing is 

flexible because the processing steps of temporal projection, controls, chemical speciation, 

temporal allocation, and spatial allocation have been separated into independent operations 

wherever possible. The results from these steps are merged together at a final stage of 

processing. 

 

SMOKE contains a number of major features that make it an attractive component of the 

modeling system. The model supports a variety of input formats from other emissions 

processing systems and models. It supports both gridded and county total land use schemes for 

biogenic emissions modeling. SMOKE can accommodate emissions files from up to 10 

countries and any pollutant can be processed by the system. For additional information about the 

SMOKE model please refer to Modeling Protocol (Appendix C). 

5.3 Selection of the Modeling Year 

A crucial step to SIP modeling is the selection of the period of time to model to represent current 

air quality conditions and to project changes in air quality in response to changes in emissions. 

The year 2002 was selected as the base year for several reasons. 

The USEPA’s April 2007 Guidance on the use of Models and Other Analyses for Demonstrating 

Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze identifies specific goals 

to consider when selecting one or more episodes for use in demonstrating reasonable progress in 

attaining the regional haze air quality goals. The USEPA recommends that episode selection 

derive from four principal criteria: 

• Simulate a variety of meteorological conditions; 
Regional Haze SIP 30 

for North Carolina Class I Areas December 17, 2007 

• Model time periods in which observed concentrations are close to the appropriate 

baseline design value or visibility impairment; 

• Model periods for which extensive air quality/meteorological data bases exist; and 

• Model a sufficient number of days so that the modeled attainment test applied at each 

monitor violating the NAAQS is based on multiple days. 

For regional haze modeling, the guidance goes further by suggesting that the preferred approach 

is to model a full, representative year. Moreover, the required relative reduction factor values 

should be based on model results averaged over the 20% worst and 20% best visibility days 

determined for each Class I are based on monitoring data from the 2000 – 2004 baseline period. 

The USEPA also lists several other considerations to bear in mind when choosing potential 

regional haze episodes including: (a) choose periods which have already been modeled, (b) 

choose periods which are drawn from the years upon which the current design values are based, 

(c) include weekend days among those chosen, and (d) choose modeling periods that meet as 

many episode selection criteria as possible in the maximum number of nonattainment or Class I 

areas as possible. Finally, the USEPA explicitly recommended in its 2007 modeling guidance to 

use 2002 as the baseline inventory year. 

VISTAS adopted a logical, stepwise approach in implementing the USEPA’s 2007 modeling 

guidance in order to identify the most preferable, representative year for regional haze modeling. 

These steps include the following: 

Representativeness of Meteorological Conditions: The VISTAS meteorological 

contractor (BAMS) identified important meteorological characteristics and data sets in 

the VISTAS region directly relevant to the evaluation of candidate annual modeling 

episodes. 

Initial Episode Typing: At the time of selection in 2003, meteorological and air quality 

data were available for 2002 for model inputs and model performance evaluation. 

VISTAS used CART analyses to evaluate visibility conditions for 2000, 2001, and 2002, 

the candidate modeling years. The year 2002 was found to be representative of 

conditions in the other two years. Subsequently, these analyses were repeated with the 

meteorological and air quality monitoring data for 2000 to 2004 to evaluate how well the 

2002 modeling year represented the full 2000-2004 baseline period. This analysis 

confirmed that visibility and PM2.5 mass in 2002 were representative of the five-year 

baseline period for the VISTAS Class I areas. This analysis is discussed in more detail in 

the project report in Appendix B. 

Data Availability: In parallel with the CART analyses, episode characterization analyses, 

collaborative investigations by VISTAS states (e.g., NCDAQ, Georgia Department of 

Natural Resources, Florida Department of Environmental Protection) intensively studied 

the availability of PM2.5, meteorological, and emissions data and representativeness of 

alternative baseline modeling periods from a regulatory standpoint. Additionally, 2002 

was the year that the USEPA was requiring states to provide emissions inventory data for 
Regional Haze SIP 31 

for North Carolina Class I Areas December 17, 2007 

the Comprehensive Emissions Reporting Rule, it made sense to use 2002 as the modeling 

year to take advantage of the 2002 inventory. 

Years to be used by other RPOs: VISTAS also considered what years other RPO would 

be modeling, and several had already chosen calendar year 2002 as the modeling year. 

After a lengthy process of integrated studies, the episode selection process culminated in the 

selection of calendar year 2002 (1 January through 31 December) as the most current, 

representative, and pragmatic choice for VISTAS regional haze modeling. All of the USEPA 

criteria for regional haze episode selection were directly considered in this process together with 

many other considerations (e.g., timing of new emissions or aerometric data deliveries by the 

USEPA or the states to the modeling teams). 

5.4 Modeling Domains 

5.4.1 Horizontal Modeling Domain 

The USEPA’s 2007 modeling guidance recommends a 12-km modeling grid resolution for 

PM2.5 modeling while a 36-km grid is considered acceptable for regional haze. For the VISTAS 

modeling, a coarse 36-km grid resolution was used for modeling the entire contential United 

States and a finer 12-km grid was used to model the eastern United States. 

The CMAQ model was run in one-way nested grid mode. This allowed the larger outer domains 

to feed concentration data to the inner nested domain. Two-way nesting was not considered due 

to numerical and computational uncertainty associated with the technique. 

The horizontal coarse grid modeling domain boundaries were determined through a national 

effort to develop a common grid projection and boundary. A smaller 12-km grid, modeling 

domain was selected in an attempt to balance location of areas of interest, such as ozone and fine 

particulate matter nonattainment areas, as well as Class 1 areas for regional haze. Processing 

time was also a factor in choosing a smaller 12-km grid, modeling domain. 

The coarse 36-km horizontal grid domain covers the continental United States. This domain was 

used as the outer grid domain for MM5 modeling with the CMAQ domain nested within the 

MM5 domain. Figure 5.4.1-1 shows the MM5 horizontal domain as the outer most, blue grid 

with the CMAQ 36-km domain nested in the MM5 domain. 
Regional Haze SIP 32 

for North Carolina Class I Areas December 17, 2007 

Figure 5.4.1-1. The MM5 horizontal domain is the outer most, blue grid, with the CMAQ 

36-km domain nested in the MM5 domain. 

To achieve finer spatial resolution in the VISTAS states, a one-way nested high resolution 

(12-km grid resolution) was used. Figure 5.4.1-2 shows the 12-km grid, modeling domain for 

the VISTAS region. The modeling results from this modeling domain are which the reasonable 

progress goals will be assessed. 

Figure 5.4.1-2. A more detailed view of the 12-km grid over the VISTAS region. 
Regional Haze SIP 33 

for North Carolina Class I Areas December 17, 2007 

5.4.2 Vertical Modeling Domain 

The CMAQ vertical structure is primarily defined by the vertical grid used in the MM5 

modeling. The MM5 model employed a terrain following coordinate system defined by 

pressure, using 34 layers that extend from the surface to the 100 mb. A layer-averaging scheme 

was used to generate 19 vertical layers for CMAQ to reduce the computational cost of the 

CMAQ simulations. The effects of layer averaging were evaluated in conjunction with the 

VISTAS modeling effort and was found to have a relatively minor effect on the model 

performance metrics when both the 34-layer and a 19-layer CMAQ models were compared to 

ambient monitoring data. 

 

6.0 MODEL PERFORMANCE EVALUATION 

The initial modeling effort focused on evaluating previous regional air quality modeling 

applications and testing candidate model configurations for the SMOKE emissions and CMAQ 

model for the VISTAS 36-km and 12-km modeling domains. This effort resulted in a report 

recommending the model configuration for the annual emissions and air quality modeling, which 

is included as part of the VISTAS Emissions and Air Quality Modeling Protocol. The evaluation 

of the meteorological modeling configuration can be found in Appendix F.1, with a summary of 

the final meteorological and air quality modeling configuration in the modeling protocol 

contained in Appendix E and Appendix C, respectively. 

Air quality model performance for the 2002 modeling year was initially tested in 2004 using an 

early version of the VISTAS emissions inventory. In keeping with the one-atmosphere objective 

of the CMAQ modeling platform, model performance was evaluated based on measured ozone, 

fine particles, and acid deposition in the Air Quality System (AQS), IMPROVE, Speciated 

Trends Network (STN), Southeastern Aerosol Research and Characterization (SEARCH), 

National Acid Deposition Program (NADP) and Clean Air Status and Trends Network 

(CASTNet) monitoring networks (Figure 6.0-1). A detailed examination of the results was 

published in 2005 in the Journal of Air and Waste Management (see Appendix B.3) as well as 

being summarized in Appendix B.1. 
Regional Haze SIP 34 

for North Carolina Class I Areas December 17, 2007 

Figure 6.0-1: Monitoring Networks used for VISTAS 2002 model performance evaluation, 

and their location within the VISTAS 12km domain. 

6.1 Modeling Performance Goals, and Criteria 

In 2004, VISTAS established model performance goals and criteria for components of fine 

particle mass (Table 6.1-1) based on previous model performance for ozone and fine particles. 

The USEPA’s 2007 modeling guidance for fine particulate matter at the time noted that PM 

models might not be able to achieve the same level of performance as ozone models. VISTAS’s 

evaluation considered several statistical performance measures and displays. Fractional bias and 

mean fractional error were selected as the most appropriate metrics to summarize model 

performance; other metrics were also calculated and are included for IMPROVE monitors in the 

full model performance evaluation (Appendix F.2). 
Regional Haze SIP 35 

for North Carolina Class I Areas December 17, 2007 

Table 6.1-1: Established model performance goals and criteria for the component species of 

fine particle mass. 

Fractional Bias Mean Fractional 

Error 

Comment 

<15% <35% Goal for PM model performance based on ozone 

model performance, considered excellent performance 

<30% <50% Goal for PM model performance, considered good 

performance 

<60% <75% 

Criteria for PM model performance, considered 

average performance. Exceeding this level of 

performance indicates fundamental concerns with the 

modeling system and triggers diagnostic evaluation. 

Several graphic displays of model performance were prepared including: 

1. Scatter plots of predicted and observed concentrations and deposition by species, 

monitoring network, and month 

2. Time series plots of predicted and observed concentrations and deposition by species, 

monitoring site, and month 

3. Spatially average time series plots 

4. Time series plots of monthly fractional bias and error for a species, region, and network 

5. Performance goal plots (“soccer plots”) that summarize model performance by species, 

region, season 

6. Concentration performance plots (“bugle plots”) that display fractional bias or error as a 

function of concentration by species, region, monitoring network, and month 

The “soccer plots” and “bugle plots” are relatively new tools in model performance evaluations, 

and have recently been included as model performance evaluation displays in the USEPA’s 2007 

modeling guidance for ozone, PM2.5, and regional haze. Both “soccer plots” and “bugle plots” 

allow for convenient way to examine model performance with respect to set goals and criteria. 

The bugle plots have the added benefit of adjusting the goals and criteria to consider the 

concentration of the species. Analysis of “bugle plots” generally suggests that greater emphasis 

should be placed on performance of those components with the greatest contribution to PM mass 

and visibility impairment (e.g. sulfate and organic carbon) and that greater bias and error could 

be accepted for components with smaller contributions to total PM mass (e.g. elemental carbon, 

nitrate, and soil). 

6.2 VISTAS Domain-Wide Performance 

Further discussion of model performance in this document will focus on the comparison of 

observational data from the IMPROVE monitors and model output data from the VISTAS 2002 

actual annual air quality modeling. Focus is limited to the IMPROVE monitoring network as 

these sites are the locations used in projecting visibility improvement goals in the Class I areas. 

The evaluation will primarily focus on the air quality model’s performance with respect to 

individual components of PM2.5, as good model performance of the component species will 

dictate good model performance of total or reconstituted PM2.5. Model performance of the total 
Regional Haze SIP 36 

for North Carolina Class I Areas December 17, 2007 

PM2.5 and the resulting total light extinction will also be provided as a means to discuss the 

overall model performance for this SIP. 

In the analyses, mean fractional bias (error) is used in lieu of mean bias (error), to prevent low 

observations and model predictions from skewing the metrics. A full list of model performance 

statistics is found in Appendix F.2. The soccer and bugle plots for the all of the VISTAS 

IMPROVE monitors are included here for summary purposes. The goal and criteria levels used 

for regional haze model performance were 30% and 60%, respectively, for mean fractional bias 

and 50% and 75%, respectively, for mean fractional error. Plots have been developed for the 

average monthly concentrations and the performance statistics for all of the most significant light 

scattering component species (Sulfate, Nitrate, and Organic Carbon) for the 20% best days and 

20% worst days. Plots for individual IMPROVE monitors associated with North Carolina 

Class I areas are included in Appendix F.2. 

The soccer plots of monthly concentrations (Figures. 6.2-1 and 6.2-2) show that values for nitrate 

generally fall outside of criteria performance thresholds (red box). Sulfates and organic carbon 

generally fall within goal thresholds (green box), with a couple of months falling just outside the 

goal thresholds but well within the criteria thresholds. In these figures, each point represents a 

month. Figure 6.2-3 contains separate soccer plots for each season. The seasonal plots 

emphasize poorer nitrate performance in the summer, when observed nitrate is quite low and 

predicted nitrate is even lower. When concentration is factored into performance criteria, nitrate 

performance improves with respect to mean fractional bias and mean fractional error 

(Figures 6.2-4 and 6.2-5). 

Figure 6.2-1: Soccer plot depicting both the mean fractional error and fractional bias for 

component concentration for all VISTAS sites. 

All Sites CMAQ 12km - 2002 Monthly

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Fractional Bias

Mean Fractional Error 

Sulfate

Nitrate

Organics

Criteria

Goal
Regional Haze SIP 37 

for North Carolina Class I Areas December 17, 2007 

All Sites CMAQ 12km - 2002 Monthly

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

-75.0 -25.0 25.0 75.0

Fractional Bias

Mean Fractional Error 

Sulfate

Nitrate

Organics

Criteria

Goal

Figure 6.2-2: A zoomed view of the soccer plot depicting both the mean fractional error 

and fractional bias for component concentration for all VISTAS sites. 

Figure 6.2-3: Seasonal soccer plots for all VISTAS IMPROVE monitors. 

All Sites CMAQ 12km - 2002 Spring Monthly

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Fractional Bias

Mean Fractional Error

Sulfate

Nitrate

Ammon.

Organics

EC

Soils

PM2.5

PM10

CM

Criteria

Goal

All Sites CMAQ 12km - 2002 Summer Monthly

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Fractional Bias

Mean Fractional Error

Sulfate

Nitrate

Ammon.

Organics

EC

Soils

PM2.5

PM10

CM

Criteria

Goal

All Sites CMAQ 12km - 2002 Fall Monthly

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Fractional Bias

Mean Fractional Error

Sulfate

Nitrate

Ammon.

Organics

EC

Soils

PM2.5

PM10

CM

Criteria

Goal

All Sites CMAQ 12km - 2002 Winter Monthly

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

-180.0 -120.0 -60.0 0.0 60.0 120.0 180.0

Fractional Bias

Mean Fractional Error

Sulfate

Nitrate

Ammon.

Organics

EC

Soils

PM2.5

PM10

CM

Criteria

Goal
Regional Haze SIP 38 

for North Carolina Class I Areas December 17, 2007 

Figure 6.2-4: Bugle plot of the mean fraction bias for particulate matter and its component 

concentrations for all VISTAS sites. 

Figure 6.2-5: Bugle plot of mean fraction error for particulate matter and its component 

species for all VISTAS sites. 

Additionally, performance assessed at the “one atmosphere” level was also deemed acceptable 

for ozone and particulate matter at various monitoring sites (STN, FRM, CASTNet, etc.). 

Overall, VISTAS found the modeling results to be representative and acceptable for use in 

modeling projection for ozone, particulate matter, and regional haze. 

All Sites CMAQ 12km - 2002 Monthly

0.0

50.0

100.0

150.0

200.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Average Concentration (μg/m3)

Mean Fractional Error 

Sulfate

Nitrate

Organics

Criteria

Goal

All Sites CMAQ 12km - 2002 Monthly

-200.0

-150.0

-100.0

-50.0

0.0

50.0

100.0

150.0

200.0

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Average Concentration (μg/m3)

Mean Fractional Bias 

Sulfate

Nitrate

Organics

(+) Criteria

(+) Goal

(-) Goal

(-) Criteria
Regional Haze SIP 39 

for North Carolina Class I Areas December 17, 2007 

6.3 North Carolina Class 1 Areas Performance 

The following section provides stack bar charts comparing observed PM2.5 composition and 

modeled PM2.5 composition. The charts have been split into two charts, with the first displaying 

the 20% best days followed by the chart for the 20% worst days. Stacked bar charts have been 

developed for each of the four IMPROVE monitoring sites relevant to North Carolina: Great 

Smoky Mountains National Park, Linville Gorge Wilderness Area, Shining Rock Wilderness 

Area, and Swanquarter Wildlife Refuge (for the location of these areas see Figure 1.4-1). The 

Great Smoky Mountains National Park IMPROVE monitor is used to represent the Joyce 

Kilmer-Slickrock Wilderness Area. 

The stacked bar chart allows a side-by-side comparison of the each day's observed and modeled 

compositional and total light extinction. Within each bar the color codes are: 

•Yellow = light extinction due to sulfates (bextSO4) 

•Red = light extinction due to nitrates (bextNO3) 

•Green = light extinction due to organic carbon (bextOC) 

•Black = light extinction due to elemental (bextEC) 

•Brown = light extinction due to soil (bextSoil) 

•Grey = light extinction due to coarse mass (bextCM) 

The components are presented in the same order for both the observed (left hand bar) and 

modeled bar (right hand bar), so it easy to identify days when the prediction light extinction for 

the component differs from the observed. The total height of the bar provides the total 

reconstructed particulate matter light extinction value. 
Regional Haze SIP 40 

for North Carolina Class I Areas December 17, 2007 

Figure 6.3-1: Stacked bar chart for Great Smoky Mountains National Park on the 20% 

best days (top) and 20% worst days (bottom). Observed composition is presented in the left 

hand bar, with modeled composition represented by the right hand bar. 

Best 20% Obs (left) vs 2002gt2a (right) at GRSM1

0

10

20

30

40

50

60

70

80

90

100

8 11 14 23 32 38 50 59 62 68 89 116 194 257 269 299 302 308 320 326 341 347 356

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4

Worst 20% Obs (left) vs 2002gt2a (right) at GRSM1

0

50

100

150

200

250

300

350

400

56 122 128 137 152 164 170 173 182 188 191 197 203 212 215 218 221 224 227 233 248 251 254 260

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4
Regional Haze SIP 41 

for North Carolina Class I Areas December 17, 2007 

Figure 6.3-2: Stacked bar chart for Linville Gorge Wilderness Area on the 20% best days 

(top) and 20% worst days (bottom). Observed composition is presented in the left hand 

bar, with modeled composition represented by the right hand bar. 

Best 20% Obs (left) vs 2002gt2a (right) at LIGO1

0

5

10

15

20

25

30

35

5 8 11 23 26 38 62 77 89 104 116 119 302 308 320 326 341 347 356 359 362

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4

Worst 20% Obs (left) vs 2002gt2a (right) at LIGO1

0

50

100

150

200

250

300

350

122 128 137 149 152 170 191 203 206 209 212 215 218 221 224 233 236 239 248 251 254 260

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4
Regional Haze SIP 42 

for North Carolina Class I Areas December 17, 2007 

Figure 6.3-3: Stacked bar chart for Shining Rock Wilderness Area on the 20% best days 

(top) and 20% worst days (bottom). Observed composition is presented in the left hand 

bar, with modeled composition represented by the right hand bar. 

Best 20% Obs (left) vs 2002gt2a (right) at SHRO1

0

5

10

15

20

25

30

35

40

45

50

5 8 11 26 38 50 68 71 86 89 104 257 269 299 302 308 320 326 341 344 347 353 359 362

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4

Worst 20% Obs (left) vs 2002gt2a (right) at SHRO1

0

100

200

300

400

500

600

128 137 152 155 161 164 170 182 185 188 191 197 203 206 212 215 218 221 224 233 248 251 254 260 266

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4
Regional Haze SIP 43 

for North Carolina Class I Areas December 17, 2007 

Figure 6.3-4: Stacked bar chart for Swanquarter Wildlife Refuge on the 20% best days 

(top) and 20% worst days (bottom). Observed composition is presented in the left hand 

bar, with modeled composition represented by the right hand bar. 

Best 20% Obs (left) vs 2002gt2a (right) at SWAN1

0

5

10

15

20

25

30

35

40

45

50

14 26 68 104 125 173 176 194 221 227 242 251 263 269 284 290 314 320 332 335 344 353 359

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4

Worst 20% Obs (left) vs 2002gt2a (right) at SWAN1

0

50

100

150

200

250

5 53 56 110 119 122 128 146 185 188 197 200 209 212 233 236 254 260 278 293 326 329 341

Julian Date

bext (1/Mm)

bextCM

bextSOIL

bextEC

bextOC

bextNO3

bextSO4
Regional Haze SIP 44 

for North Carolina Class I Areas December 17, 2007 

A cursory view of the stacked bars charts reiterates that sulfates are a large contributor to light 

extinction in the North Carolina Class I areas on both the 20% best days and the 20% worst days. 

The bar charts also suggest that organic carbon and nitrates are important on the 20% best days 

at the four IMPROVE sites of interest for North Carolina. The bar charts for the 20% best 

reiterate the general under prediction seen in previous sections. Model performance at Linville 

Gorge and Shining Rock Wilderness areas are arguably better than both the Great Smoky 

Mountains National Park and Swanquarter Wildlife Refuge for the 20% best days. The under 

prediction of sulfate on most of the 20% best days appears to be the reason for poor model 

performance, with the under prediction of nitrate observed on some days. On most 20% best 

days there is a small under-prediction of sulfate and on some days there is a large nitrate under 

prediction. 

Comparing the 20% best day charts to the 20% worst days charts, one notices that the various 

components of particle pollution play a more prominent role in the 20% best days than with the 

20% worst days. Also, the species make up on the 20% best days varies more widely compared 

to the 20% worst days. This suggests accurately modeling each species is especially important 

on the 20% best days. Note the differences in scale of the two charts; on the 20% best days 

modeled extinction is generally less than 20 Mm-1 different from measured values. For 20% 

worst days total differences between modeled and measured extinction varies from near zero to 

greater than 200 Mm-1. 

With the bar chart for the 20% worst days, you can see model performance does improve across 

the sites. Light extinction due to sulfate prediction is better, but still falls short on some days. 

Light extinction due to organic carbon also become more important to total light extinction. 

Much like the sulfate component, the organic carbon component accuracy has improved 

performance over the 20% best day series, thought some days are still under predicted. 

Overall, the NCDAQ found model performance to fall within acceptable limits for model 

performance. The NCDAQ further asserts the one-atmosphere modeling performed by the 

VISTAS contractors is representative of conditions in the southeastern states and is applicable 

for use in setting reasonable progress goals for the Class I areas. 

7.0 LONG-TERM STRATEGY FOR NORTH CAROLINA CLASS I AREAS 

As stated in Section 1.3, the regional haze rule requires a State to establish reasonable progress 

goals for Class I areas within the State, expressed in deciviews, that provide for reasonable 

progress toward achieving natural visibility conditions by 2064. This first set of reasonable 

progress goals must be met through measures contained in the State’s long-term strategy 

covering the period from the baseline through 2018. States are also to evaluate the effects of 

emissions from their State on Class I areas in other states. This section discusses development of 

North Carolina’s long-term strategy. 

7.1 Overview of the Long-Term Strategy Development Process 

The process NCDAQ’s used to develop its long-term strategy was to address the following set of 

questions: 
Regional Haze SIP 45 

for North Carolina Class I Areas December 17, 2007 

a. Assuming implementation of existing federal and state air regulatory requirements, 

how much visibility improvement would be expected at each Class I areas in North 

Carolina between now and 2018 compared to the area’s uniform rate of progress? 

b. What additional emission controls represent BART in North Carolina? 

c. If additional emission reductions were needed, from what pollutants and source 

categories would the greatest visibility benefits be realized between the baseline and 

2018? 

d. Based on the pollutants identified in (c) above, determine the geographic locations 

(i.e., area of influence) for each Class I area where these emissions having the 

greatest impact on visibility are found? 

e. What types of emissions sources do we find in those areas of influence? 

f. Which specific individual sources in those areas of influence have the greatest 

visibility impacts at a given Class I area? 

g. What additional emission controls represent reasonable control measures for those 

sources identified in (f) above? 

h. Given the additional emission reductions from BART and reasonable control 

measures identified, how much visibility improvement, compared to the glidepath, is 

expected at Class I areas in North Carolina between the baseline and 2018? 

7.2 Expected Visibility Results in 2018 for North Carolina Class I Areas under existing and 

planned emissions controls 

There are significant control programs being implemented between the baseline period and 2018. 

Emission reductions from these control programs are projected to achieve substantial visibility 

improvement by 2018 in the North Carolina Class I areas. These programs are described in more 

detail below. 

7.2.1 Federal and State Control Requirements 

CAIR. CAIR will permanently cap emissions of SO2 and NOx from EGUs in the eastern United 

States by 2015. When fully implemented, CAIR will reduce SO2 emissions from EGUs in these 

states by more than 70%, and NOx emissions by more than 60%, from 2003 levels. 

 

NOx SIP Call. Phase I of the NOx SIP call applies to certain EGUs and large non-EGUs, 

including large industrial boilers and turbines, and cement kilns. Those states affected by the 

NOx SIP call in the VISTAS region have developed rules for the control of NOx emissions that 

have been approved by the USEPA. The NOx SIP Call has resulted in a 68% reduction in 

summertime NOx emissions from large stationary combustion sources in North Carolina. For 
Regional Haze SIP 46 

for North Carolina Class I Areas December 17, 2007 

this analysis, we capped the emissions for NOx SIP call-affected sources at 2007 levels, and 

carried forward the capped levels for the 2009 and 2018 future year inventories. 

North Carolina CSA. Under the CSA, enacted in 2002, coal-fired power plants in North 

Carolina must achieve a 77-percent cut in NOx emissions by 2009 and a 73-percent cut in SO2 

emissions by 2013. This legislation establishes annual caps on both SO2 and NOx emissions for 

the two primary utility companies in North Carolina, Duke Energy and Progress Energy. These 

reductions must be made in North Carolina, and allowances cannot be sold. 

Georgia Multi-pollutant Bill. Georgia enacted regulations in summer 2007 to require coal fired 

power plants in Georgia to reduce SO2 by approximately 90%, NOx by approximately 50%, and 

mercury by an estimated 75-85% by 2015. Reductions will affect 21 units at seven facilities. 

The rule requires specific controls on specific units according to a specific schedule. This is not 

a cap and trade rule, thus there are no allowances to be banked, sold or traded. 

Consent Agreements. Under a settlement agreement, by 2008, Tampa Electric will install 

permanent emissions-control equipment to meet stringent pollution limits; implement a series of 

interim pollution-reduction measures to reduce emissions while the permanent controls are 

designed and installed; and retire pollution emission allowances that Tampa Electric or others 

could use, or sell to others, to emit additional NOx, SO2, and PM. 

Virginia Electric and Power Company agreed to spend $1.2 billion by 2013 to eliminate 237,000 

tons of SO2 and NOx emissions each year from eight coal-fired electric generating plants in 

Virginia and West Virginia. 

A 2002 agreement calls for Gulf Power to upgrade its operation to cut NOx emission rates by 

61% at its Crist generating plant by 2007, with major reductions beginning in early 2005. The 

Crist plant is a significant source of NOx emissions in the Pensacola area. 

In October 2007, American Electric Power agreed to spend $4.6 billion dollars to eliminate 

72,000 tons of NOx emissions each year by 2016 and 174,000 tons of SO2 emissions each year 

by 2018 from sixteen coal-fired power plants located in Indiana, Kentucky, Ohio, Virginia and 

West Virginia. 

One-hour ozone SIPs (Atlanta / Birmingham / Northern Kentucky). New SIPs have been 

submitted to the USEPA to demonstrate attainment of the one-hour ozone NAAQS. These SIPs 

require NOx reductions from specific coal fired power plants and address transportation plans in 

these cities. 

NOx RACT in 8-hour Nonattainment Area SIPs. The NCDAQ’s SIP for the Charlotte/Gastonia/ 

Rock Hill nonattainment area includes Reasonable Achievable Control Technology (RACT) for 

NOx for two facilities located in the nonattainment area: Philip Morris USA and Norandal USA. 

These controls were also modeled in 2018. Additional RACT controls may be realized as other 

companies subject to RACT complete the determination, but RACT-level controls were assumed 

for just these two sources. 
Regional Haze SIP 47 

for North Carolina Class I Areas December 17, 2007 

Heavy Duty Diesel (2007) Engine Standard (for on-road trucks and buses). The USEPA set a 

PM emissions standard for new heavy-duty engines of 0.01 grams per brake-horsepower-hour 

(g/bhp-hr), to take full effect for diesel engines in the 2007 model year. This rule also includes 

standards for NOx and non-methane hydrocarbons (NMHC) of 0.20 g/bhp-hr and 0.14 g/ bhp-hr, 

respectively. These NOx and NMHC standards will be phased in together between 2007 and 

2010, for diesel engines. Sulfur in diesel fuel must be lowered to enable modern pollutioncontrol technology to be effective on these trucks and buses. The USEPA will require a 97 

percent reduction in the sulfur content of highway diesel fuel from its current level of 500 parts 

per million (low sulfur diesel, or LSD) to 15 parts per million (ultra-low sulfur diesel, or ULSD). 

Tier 2 Tailpipe (On-road vehicles). The USEPA mobile source rules include the Tier 2 fleet 

averaging program, modeled after the California LEV II standards. Manufacturers can produce 

vehicles with emissions ranging from relatively dirty to zero emissions, but the mix of vehicles a 

manufacturer sells each year must have average NOx emissions below a specified value. Tier 2 

standards became effective in the 2005 model year. 

Large Spark Ignition and Recreational Vehicle Rule. The USEPA has adopted new standards for 

emissions of NOx, hydrocarbons, and carbon monoxide from several groups of previously 

unregulated nonroad engines. Included in these are large industrial spark-ignition engines and 

recreational vehicles. Nonroad spark-ignition engines are those powered by gasoline, liquid 

propane gas, or compressed natural gas rated over 19 kilowatts (kW) (25 horsepower). These 

engines are used in commercial and industrial applications, including forklifts, electric 

generators, airport baggage transport vehicles, and a variety of farm and construction 

applications. Nonroad recreational vehicles include snowmobiles, off-highway motorcycles, and 

all-terrain-vehicles. These rules were initially effective in 2004 and will be fully phased-in by 

2012. 

Nonroad Diesel Rule. This rule sets standards that will reduce emissions by more than 90 

percent from nonroad diesel equipment, and reduce sulfur levels by 99 percent from current 

levels in nonroad diesel fuel starting in 2007. This step will apply to most nonroad diesel fuel in 

2010 and to fuel used in locomotives and marine vessels in 2012. 

Industrial Boiler/Process Heater MACTs. The USEPA issued final rules to substantially reduce 

emissions of toxic air pollutants from industrial, commercial and institutional boilers and process 

heaters. These rules reduce emissions of a number of toxic air pollutants, including hydrogen 

chloride, manganese, lead, arsenic and mercury by 2009. This rule also reduces emissions of 

SO2 and PM in conjunction with the toxic air pollutant reductions. The applied Maximum 

Achievable Control Technology (MACT) control efficiencies were 4 percent for SO2 and 40 

percent for PM10 and PM2.5. The USEPA’s industrial boiler MACT rules were vacated on June 

8, 2007. The VISTAS states decided to leave these controls in the modeling since it is believed 

that by 2018 the USEPA will have re-promulgated a boiler MACT rule or states will have 

addressed the issue through state rule making.

Combustion Turbine and Reciprocating Internal Combustion Engines MACTs. The projection 

inventories do not include the NOx co-benefit effects of the MACT regulations for Gas Turbines 
Regional Haze SIP 48 

for North Carolina Class I Areas December 17, 2007 

or stationary Reciprocating Internal Combustion Engines, which the USEPA estimates to be 

small compared to the overall inventory.

VOC 2-, 4-, 7-, and 10-year MACT Standards. Various point source MACTs and associated 

emission reductions were implemented. Reductions occurring before 2002 were assumed to be 

accounted for in the 2002 base year inventory. 

7.2.2 Additional State programs to reduce emissions 

In addition to accounting for specific emission reductions due to ongoing air pollution programs 

as required under the regional haze rule section 308 (d)(3)(v)(A), states are also required to 

consider the air quality benefits of measures to mitigate the impacts of construction activities 

[section 308(d)(3)(v)(B)] and agricultural and forestry smoke management techniques 

[section 308(d)(3)(v)(E)]. These state measures are discussed in more detail in Appendix H. 

7.2.3 Projected 2009 and 2018 Emissions Inventories 

The inventories for 2009 and 2018 account for post-2002 emission reductions from promulgated 

and proposed federal, state, local, and site-specific control programs as of July 1, 2004. In 

general, emissions inventories were developed for 2009 and 2018 using current control 

information in North Carolina. 

For EGUs, IPM results were adjusted based on state and local air agencies knowledge of planned 

emission controls at specific EGUs. These updates are documented in the MACTEC emissions 

inventory report “Documentation of the 2002 Base Year and 2009 and 2018 Projection Year 

Emission Inventories for VISTAS” dated February 2007 (Appendix D). 

For non-EGUs, VISTAS used recently updated growth and control data consistent with the data 

used in the USEPA’s CAIR analyses (Clean Air Interstate Rule Emissions Inventory Technical 

Support Document, March 2005) supplemented by state and local air agencies data and updated 

forecasts from the Department of Energy (DOE). 

Area source controls were estimated using known state level Stage I controls on gasoline 

dispensing facilities and open burning estimates, as well as controls used to project emissions for 

the USEPA’s Heavy Duty Diesel rulemaking and for the CAIR rulemaking. 

Mobile source controls included local controls underlying the 2002 baseline inventory (vehicle 

emission inspection, Stage II vapor recovery, anti-tampering, etc.) with changes based on 

specific State input. The future year inventories were developed by running the MOBILE6.2 

model for each year modeled. The future year emissions for the off-road mobile sources 

included in the USEPA NONROAD model were estimated by running the model for each future 

year. For the other off-road mobile source categories control data and projections for 1996, 

2010, 2015, and 2020 were obtained from the USEPA's CAIR Technical Support Document, and 

straight-line projections were used to estimate 2009 and 2018 levels. 
Regional Haze SIP 49 

for North Carolina Class I Areas December 17, 2007 

The following bar charts show expected decreases in emissions of SO2 and NOx across the 

VISTAS states from 2002 through 2018. (Similar charts for other visibility impairing pollutants 

are contained in Appendix H). Note that for SO2 emissions in particular, which are the largest 

contributors to haze, emissions from electric generating facilities are expected to decrease 

dramatically (70%) between 2002 and 2018. However, even after implementation of CAIR, 

EGU emissions are projected to remain the largest contributor to haze, comprising more than 

half of remaining SO2 emissions in most states. 

Figure 7.2.3-1. Annual SO2 emissions for 2002, 2009, and 2018 in the VISTAS states. 

Figure 7.2.3-2. Annual NOx emissions in 2002, 2009, and 2018 in the VISTAS States. 

West Virginia

Alabama

Florida

Kentucky

Georgia

Mississippi

South Carolina

North Carolina

Tennessee

Virginia

100

200

300

400

500

600

700

Annual SO2 (Thousand Tons)

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

2002

2009

2018

West Virginia

Alabama

Florida

Kentucky

Georgia

Mississippi

South Carolina

North Carolina

Tennessee

Virginia

100

200

300

400

500

600

700

Annual SO2 (Thousand Tons)

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

2002

2009

2018

Alabama

Florida

Kentucky

Georgia

Mississippi

South Carolina

North Carolina

Tennessee

Virginia

100

200

300

400

500

600

700

Annual SO2 (Thousand Tons)

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

Miscellaneous

Nonroad

Onroad

Industrial

Other Fuel Combustion

EGU

2002

2009

2018

0

100

200

300

400

500

600

700

800

900

1,000

Alabama

Florida

Georgia

Kentucky

Mississippi

North Carolina

South Carolina

Tennessee

Virginia

West Virginia

Annual NOx (Thousand Tons)

Miscellaneous

Nonroad Onroad

Industrial Other Fuel Combustion EGU

2002

2009

2018

0

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600

700

800

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1,000

Alabama

Florida

Georgia

Kentucky

Mississippi

North Carolina

South Carolina

Tennessee

Virginia

West Virginia

Annual NOx (Thousand Tons)

Miscellaneous

Nonroad Onroad

Industrial Other Fuel Combustion EGU

Miscellaneous

Nonroad Onroad

Industrial Other Fuel Combustion EGU

2002

2009

2018
Regional Haze SIP 50 

for North Carolina Class I Areas December 17, 2007 

Summary of Emissions Inventories for 2009 and 2018

Tables 7.2.3-1 and 7.2.3-2 are summaries of the 2009 and 2018emission inventory, respectively. 

The complete inventory and discussion of the methodology is contained in Appendix D. 

Table 7.2.3-1. 2009 Emissions Inventory Summary for North Carolina. 

VOC NOx PM2.5 PM10 NH3 SO2 

Point 62,161 101,236 26,360 36,007 1,730 284,802 

Area 200,873 45,382 90,729 315,004 170,734 6,281 

On-Road Mobile 168,676 201,609 3,493 5,572 11,825 1,503 

Non-Road Mobile 74,056 70,997 5,760 6,055 72 1,892 

Biogenics 1,213,819 17,888 NA NA NA NA 

TOTAL 1,719,585 437,112 126,342 362,638 184,361 294,478 

Table 7.2.3-2. 2018 Emissions Inventory Summary for NC. 

VOC NOx PM2.5 PM10 NH3 SO2 

Point 71,247 94,276 37,789 48,354 2,073 148,972 

Area 203,132 49,514 93,406 338,872 181,333 6,674 

On-Road Mobile 101,099 87,791 2,123 4,392 14,065 1,481 

Non-Road Mobile 61,327 49,046 4,069 4,298 83 905 

Biogenics 1,213,819 17,888 NA NA NA NA 

TOTAL 1,650,624 298,515 137,387 395,916 197,554 158,032 

7.2.4 Model Results for the 2018 Inventory Compared to the Uniform Rate of Progress 

Glidepaths for North Carolina Class I Areas 

Using 2000 - 2004 IMPROVE monitoring data, the deciview values for the 20% best days in 

each year are averaged together, producing a single average deciview value for the best days. 

Similarly, the deciview values for the 20% worst days in each year are averaged together, 

producing a single average deciview value for the worst days. The average values represent the 

current visibility conditions. 

The predicted visibility improvement is calculated by comparing the 2002 typical year modeling 

results for the 12-km grid to the 2018 12-km modeling results to develop a relative reduction 

factor. This factor is then applied to the current visibility condition values to estimate the future 

visibility. Detailed discussions about how the relative reduction factors are calculated can be 

found in Appendix G. 

For the 20% worst days in the North Carolina Class I areas, Figures 7.2.4-1 through 7.2.4-5 

graphically compare the visibility which would result with each area’s uniform rate of progress 

(red line) to the predicted visibility from 2004 to 2018 due to modeled emission reductions 

expected by federal and state control programs (purple line). Similarly, for the 20% best days in 

each area, Figures 7.2.4-6 through 7.2.4-10 graphically compare visibility with no degradation 
Regional Haze SIP 51 

for North Carolina Class I Areas December 17, 2007 

over the first planning period (red line) to the predicted visibility from 2004 to 2018 due to 

modeled emission reductions expected by federal and state control programs (purple line). 

Figure 7.2.4-1. Reasonable progress assessment compared to Uniform Rate of Progress for 

20% worst days at Great Smoky Mountains National Park. 

Figure 7.2.4-2. Reasonable progress assessment compared to Uniform Rate of Progress for 

20% worst days at Joyce Kilmer-Slickrock Wilderness Area. 

Reasonable Progress Assessment

Great Smoky Mountains - 20% Worst Days

New IMPROVE Equation, 12 km grid

30.28

28.67

25.79

22.59

19.38

16.18

12.97

11.05

23.66

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Glide Path Natural Condition (Worst Days) Observation Method 1 Prediction

Reasonable Progress Assessment

Joyce Kilmer - Slickrock - 20% Worst Days

New IMPROVE Equation, 12 km grid

30.28

28.67

25.79

22.59

19.38

16.18

12.97

11.05

23.66

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Glide Path Natural Condition (Worst Days) Observation Method 1 Prediction
Regional Haze SIP 52 

for North Carolina Class I Areas December 17, 2007 

Figure 7.2.4-3. Reasonable progress assessment compared to Uniform Rate of Progress for 

20% worst days at Linville Gorge Wilderness Area. 

Figure 7.2.4-4. Reasonable progress assessment compared to Uniform Rate of Progress for 

20% worst days at Shining Rock Wilderness Area. 

Reasonable Progress Assessment

Linville Gorge - 20% Worst Days

New IMPROVE Equation, 12 km grid

28.77

27.31

24.67

21.74

18.81

15.88

12.95

11.19

21.98

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Glide Path Natural Condition (Worst Days) Observation Method 1 Prediction

Reasonable Progress Assessment

Shining Rock - 20% Worst Days

New IMPROVE Equation, 12 km grid

28.46

27.04

24.50

21.66

18.83

16.00

13.17

11.47

22.11

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Glide Path Natural Condition (Worst Days) Observation Method 1 Prediction
Regional Haze SIP 53 

for North Carolina Class I Areas December 17, 2007 

Figure 7.2.4-5. Reasonable progress assessment compared to Uniform Rate of Progress for 

20% worst days at Swanquarter Wildlife Refuge. 

Figure 7.2.4-6 Reasonable progress assessment for 20% best days at Great Smoky 

Mountains National Park. 

Reasonable Progress Assessment

Great Smoky Mountains - 20% Best Days

New IMPROVE Equation, 12 km grid

13.58 13.58

12.15

4.54

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Baseline Natural Condition (20% Best Days) Observation Method 1 Prediction

Reasonable Progress Assessment

Swanquarter - 20% Worst Days

New IMPROVE Equation, 12 km grid

24.74 23.64

21.66

19.46

17.26

15.07

12.87 11.55

20.37

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Glide Path Natural Condition (Worst Days) Observation Method 1 Prediction
Regional Haze SIP 54 

for North Carolina Class I Areas December 17, 2007 

Figure 7.2.4-7 Reasonable progress assessment for 20% best days at Joyce KilmerSlickrock Wilderness Area 

Figure 7.2.4-8 Reasonable progress assessment for 20% best days at Linville Gorge 

Wilderness Area. 

Reasonable Progress Assessment

Linville Gorge - Best 20% Days

New IMPROVE Equation, 12 km grid

11.11 11.11

9.64

4.08

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Baseline Natural Condition (20% Best Days) Observation Method 1 Prediction

Reasonable Progress Assessment

Joyce Kilmer - Slickrock - 20% Best Days

New IMPROVE Equation, 12 km grid

13.58 13.58

12.15

4.54

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Baseline Natural Condition (20% Best Days) Observation Method 1 Prediction
Regional Haze SIP 55 

for North Carolina Class I Areas December 17, 2007 

Figure 7.2.4-9 Reasonable progress assessment for 20% best days at Shining Rock 

Wilderness Area. 

Figure 7.2.4-10 Reasonable progress assessment for 20% best days at Swanquarter Wildlife 

Refuge. 

Reasonable Progress Assessment

Shining Rock - 20% Best Days

New IMPROVE Equation, 12 km grid

7.69 7.69

6.91

2.51

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Baseline Natural Condition (20% Best Days) Observation Method 1 Prediction

Reasonable Progress Assessment

Swanquarter - 20% Best Days

New IMPROVE Equation, 12 km grid

11.99 11.99

10.96

5.46

0

5

10

15

20

25

30

35

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 2048 2052 2056 2060 2064

Year

Haziness Index (Deciviews)

Baseline Natural Condition (20% Best Days) Observation Method 1 Prediction
Regional Haze SIP 56 

for North Carolina Class I Areas December 17, 2007 

Note that at all five Class I areas in North Carolina, visibility improvements on the 20% worst 

days are expected to be better than the uniform rate of progress by 2018 based solely on 

reductions from existing and planned emissions controls. For example, at Great Smoky 

Mountains, a 4.5 dv improvement in visibility would meet uniform rate of progress in 2018; 

expected emissions reductions by 2018 are projected to achieve a 6.6 dv improvement. In fact, 

as illustrated in Figure 7.2.4-11, visibility improvements at all the VISTAS mountain Class I 

areas and most of the coastal Class I areas are projected to be better than the uniform rate of 

progress. In Figure 7.2.4-11, the predicted percentage of the target reduction achieved for the 

North Carolina Class I areas, using the new IMPROVE equation, is between 140% and 180%. 

This means that the amount of visibility improvement expected from the modeled control 

programs is 40% to 80% more than what the uniform rate of progress would be for 2018. 

In addition to improving visibility on the 20% worst visibility days, states are also required to 

protect visibility on the 20% best days at the Class I areas. As illustrated in Figure 7.2.4-12, 

visibility on the 20% best days is projected to improve in 2018 at all VISTAS Class I areas as a 

result of the emissions reductions expected from federal and state control programs. In 

Figure 7.2.4-12, the percentage of the target achieved for the North Carolina Class I areas is 

about -10%. Zero percent change would mean no change in visibility; -10% means that visibility 

is better than no change, or a 10% improvement (values lower than current conditions). 

 
Regional Haze SIP 57 

for North Carolina Class I Areas December 17, 2007 

Figure 7.2.4-11. Projected visibility improvement on 20% worst visibility days at VISTAS 

and neighboring Class I areas for the 2018 (12 km grid) 

 

Figure 7.2.4-12. Projected visibility improvement on 20% best visibility days at VISTAS 

and neighboring Class I areas for the 2018 Base G2a CMAQ run 

0%

20%

40%

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100%

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Percent of target reduction achieved

VISTAS non-VISTAS

CMAQ New IMPROVE Algorithm

CMAQ Old IMPROVE Algorithm

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Percent of target reduction achieved

VISTAS non-VISTAS

CMAQ New IMPROVE Algorithm

CMAQ Old IMPROVE Algorithm

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UPBU

Percent of target reduction achieved

VISTAS non-VISTAS

CMAQ New IMPROVE Algorithm

CMAQ Old IMPROVE Algorithm

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-10%

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UPBU

Percent of target reduction achieved

VISTAS non-VISTAS

CMAQ New IMPROVE Algorithm

CMAQ Old IMPROVE Algorithm

-50%

-40%

-30%

-20%

-10%

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UPBU

Percent of target reduction achieved

VISTAS non-VISTAS

CMAQ New IMPROVE Algorithm

CMAQ Old IMPROVE Algorithm
Regional Haze SIP 58 

for North Carolina Class I Areas December 17, 2007 

The expected change in visibility at Great Smoky Mountains between 2000-2004 baseline 

conditions on the 20% worst days and 2018 projections is illustrated in Figure 7.2.4-13 (upper 

picture). In contrast, natural background visibility conditions for the 20% worst days are 

illustrated in the bottom picture in Figure 7.2.4-13. These images were generated using 

WINHAZE, a photographic imaging tool that accounts for the effect of concentrations of fine 

particle components and relative humidity on visibility. These images illustrate that notable 

improvements in visibility are expected by 2018 and that significantly greater improvements are 

needed to reach natural background conditions. 

Figure 7.2.4-13. Visibility improvement on 20 % haziest days at Great Smoky Mountains 

between 2000-2004 baseline conditions (upper left) and 2018 projected visibility (upper 

right). Projected visibility on 20 % haziest days for natural background (bottom). 
Regional Haze SIP 59 

for North Carolina Class I Areas December 17, 2007 

7.3 Relative Contribution from International Emissions to Visibility Impairment in 2018 at 

VISTAS Class I areas 

Emissions from Mexico, Canada, Central America, Asia, and Africa contribute to PM2.5 

loadings and visibility impairment at Class I areas in the continental United States. To evaluate 

the relative contribution of international emissions to visibility at Class I areas in the 

southeastern United States, VISTAS used a combination of modeling results from the global 

three-dimensional chemical transport model (GEOS-Chem) and CMAQ. VISTAS used the 

GEOS-Chem global model to generate initial and boundary conditions for the CMAQ modeling 

domain. GEOS-Chem was run for the 2002 modeling year using a 4 x 5 degree horizontal grid 

resolution and a 3-hour temporal resolution. Because emissions were based on monthly 

averages, the model does not capture the episodic variability in emissions. The GEOS-Chem 

outputs were used to calculate initial and boundary conditions for the national CMAQ modeling 

domain. The national CMAQ domain included portions of Canada and Mexico, so emissions for 

these countries were included within the national CMAQ modeling domain or as part of the 

boundary conditions outside the national modeling domain, as appropriate. 

Two complementary methods were used to calculate the impact of international emissions at 

Class I areas. Since the international emissions inventory used in the GEOS-CHEM model did 

not distinguish between wildfires and anthropogenic fires, all international fire emissions were 

treated as wildfire. This treatment of the international fire emissions would therefore 

underestimate the impact international anthropogenic emissions have, since the anthropogenic 

international fire emissions are not included. 

1) International emissions are represented by the difference between two GEOS-Chem runs. 

In the first run United States anthropogenic emissions were removed, and in the second 

run both United States and international anthropogenic emissions were removed. The 

difference represents international anthropogenic emissions, in the absence of United 

States anthropogenic emissions (e.g. compared to 2064 levels). Harvard University 

provided GEOS-Chem results to VISTAS for 2002 international contribution on 4 x 5 

degree grid. Concurrently Harvard modeling for the Electric Power Research Institute 

(EPRI) provided GEOS-Chem results for 2001 international contribution on a 1 x 1 

degree grid scale. 

2) International emissions are represented by the difference between two CMAQ 36-km 

simulations, both using an earlier version of the 2018 emissions and boundary conditions 

from GEOS-Chem. In the first CMAQ run, all global natural and anthropogenic 

emissions in 2018 are active. In the second CMAQ run, only global (United States and 

international) natural emissions are active. Here the impacts of international emissions 

are compared against 2018 conditions rather than natural background conditions. 

VISTAS has compared its results to results from other RPOs on the impact of international 

emissions and boundary conditions on visibility at Class I areas in 2002; the results were similar. 

As illustrated in Figure 7.3-1 for annual average contributions to sulfate at VISTAS and 

neighboring Class I areas, the estimated international contributions are higher at Class I areas 
Regional Haze SIP 60 

for North Carolina Class I Areas December 17, 2007 

near the Canadian and Mexican borders and along the eastern coast. The estimated international 

contribution is higher using CMAQ than in the GEOS-Chem runs because the grid scale is finer 

(more accurate dispersion of emissions) and because the background atmosphere includes 

loadings from current United States anthropogenic emissions (greater photochemical activity). 

Similar charts for nitrate and organic carbon mass, for impacts on 20% worst visibility days, and 

for impacts of international emissions on calculated light extinction are included in Appendix H. 

Figure 7.3-1. Estimated international emissions contributions to sulfate at VISTAS and 

neighboring Class I areas. 

In Figure 7.3-2, CMAQ projections of contributions from international emissions to PM mass on 

20% worst visibility days in 2002 at Swanquarter, North Carolina are compared to United States 

domestic contributions to PM components at the site on those days. 

 

Transboundary Man-Made Impacts

0.0

0.2

0.4

0.6

0.8

1.0

1.2

BRIG

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CACR

MINGUPBU

BRETEVER

CHAS

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LIGO

MACA

SWAN

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DOSO

SHEN

(NH

4) SO

2

4 Conc. (

g/m

3

)

GEOS_4x5 GEOS_1x1 CMAQ
Regional Haze SIP 61 

for North Carolina Class I Areas December 17, 2007 

Figure 7.3-2. PM component concentrations from US domestic sources on 20% worst 

visibility days in 2002 (left bars) and CMAQ-simulated international contributions (right 

bars) at Swanquarter, North Carolina. 

Although VISTAS assessed impacts from international emissions at the Class I areas, these 

modeling runs were to provide information to the states to understand what the potential impacts 

may be at their Class I areas. The modeling showed that for the North Carolina Class I areas the 

impacts from international emissions were between 1.3 and 1.5 dv of the current conditions. 

Since good projected emissions for areas outside of the continental United States are not readily 

available, there is no real way to assess what the impacts from international emissions would be 

for 2018, other than to assume that it would be approximately same amount as for the baseline 

current conditions. Therefore, the NCDAQ will not be accounting for international emissions in 

setting the 2018 reasonable progress goals for its Class I areas. 

Nevertheless, as the atmosphere becomes closer to natural background conditions in the future, 

the incremental contribution from international emissions will become more important. The 

information is included in this SIP documentation to provide reference for future assessments of 

reasonable progress. 

7.4 Relative Contributions to Visibility Impairment: Pollutants, Source Categories, and 

Geographic Areas 

An important step toward identifying potential reasonable control measures is to identify the key 

pollutants contributing to visibility impairment at each Class I area. To understand the relative 

benefit of further reducing emissions from different pollutants, source sectors, and geographic 

areas, VISTAS engaged the Georgia Institute of Technology to perform emission sensitivity 

Swanquarter, NC

Domestic and International Aerosol Mass by Species

20% Worst Days in 2002

0

5

10

15

20

25

30

35

Domestic

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Domestic

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Domestic

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Domestic

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Domestic

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Domestic

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Domestic

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Domestic

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Domestic

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1/5 2/22 2/25 4/20 4/29 5/2 5/8 5/26 7/4 7/7 7/16 7/19 7/28 7/31 8/21 8/24 9/11 9/17 10/5 10/20 11/22 11/25 12/7

Mass (μg/m3)

(NH4)2SO4 NH4NO3 POM LAC Soil CM Sea Salt

Swanquarter, NC

Domestic and International Aerosol Mass by Species

20% Worst Days in 2002

0

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1/5 2/22 2/25 4/20 4/29 5/2 5/8 5/26 7/4 7/7 7/16 7/19 7/28 7/31 8/21 8/24 9/11 9/17 10/5 10/20 11/22 11/25 12/7

Mass (μg/m3)

(NH4)2SO4 NH4NO3 POM LAC Soil CM Sea Salt
Regional Haze SIP 62 

for North Carolina Class I Areas December 17, 2007 

model runs using CMAQ. Emissions sensitivities were initially performed for three episodes 

representing winter and summer conditions: Jan 2002, July 2001, and July 2002. These runs 

used the initial 2018 projections inventory and considered 30% reductions from specific 

pollutants, source categories, and geographic areas. As part of a separate effort, emissions 

sensitivities were performed using a preliminary 2009 projection inventory and two, month-long 

episodes from 2002: Jun 1 – Jul 10 and Nov 19 – Dec 19. The emissions in 2009 were reduced 

by 30% for each pollutant sensitivity run. The pollutant contributions that were evaluated were: 

• SO2 from EGU sources in each VISTAS state, other RPOs in the VISTAS 12 km grid, 

and Boundary Conditions from outside the 12 km domain. 

• SO2 from non-EGU point sources in each VISTAS state, other RPOs, and Boundary 

Conditions 

• NOx from ground level sources (on-road plus off-road plus area) in each VISTAS state 

and other RPOs. In the VISTAS states, these reductions were only applied to specific 

counties that were of concern for 8-hour ozone nonattainment. 

• NOx from point (EGU plus non-EGU) sources in each VISTAS state and other RPOs 

• NH3 from all sources in VISTAS and other RPOs 

• Volatile Organic Compounds from anthropogenic and biogenic sources in the 12 km 

modeling domain 

• Primary Carbon from all ground level sources in each VISTAS state and other RPOs. In 

the VISTAS states, these reductions were only applied to specific counties that were of 

concern for PM2.5 nonattainment. 

• Primary Carbon from all point sources in each VISTAS state and other RPOs 

• Primary Carbon from all fires in each VISTAS state and other RPOs 

While the 2009 sensitivity analyses cannot be used to judge absolute contributions from each 

state or source sector, the results do indicate relative level of response among pollutants, sectors, 

and geographic areas. The NCDAQ decided to use the 2009 sensitivities to assess relative 

contribution to visibility impairment from various source sectors and believes this is an 

appropriate use of this data since the use of the emissions sensitivities is to qualitatively 

understand how reductions in emissions from various source sectors would impact visibility at 

the Class I areas. 

Results are shown in Figures 7.4-1 through 7.4-4 below for the average of the 20% worst 

visibility days for each of four North Carolina Class I areas. Responses for 20% worst days were 

calculated by averaging the responses of the 20% worst days that were modeled in the two 

episodes. For the North Carolina sites, responses on five to six of the 20% worst visibility days 

were included in these graphics. 
Regional Haze SIP 63 

for North Carolina Class I Areas December 17, 2007 

Figure 7.4-1. CMAQ projections of visibility responses on 20% worst days at Great Smoky 

Mountains to 30 % reductions from a 2009 inventory for visibility-reducing pollutants in 

different source categories and geographic areas. 

Figure 7.4-2. CMAQ projections of visibility responses on 20% worst days at Shining Rock 

to 30% reductions from a 2009 inventory for visibility-reducing pollutants in different 

source categories and geographic areas. 

Shining Rock, NC (20% Worst Days)

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

SO2_EGU

SO2_nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL

Shining Rock, NC (20% Worst Days)

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

SO2_EGU

SO2_nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL

Great Smoky Mtns, TN (20% Worst Days)

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

SO2_EGU

SO2_

nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC.

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL

Great Smoky Mtns, TN (20% Worst Days)

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

SO2_EGU

SO2_

nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC.

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL
Regional Haze SIP 64 

for North Carolina Class I Areas December 17, 2007 

Figure 7.4-3. CMAQ projections of visibility responses on 20% worst days at Linville 

Gorge to 30% reductions from a 2009 inventory for visibility-reducing pollutants in 

different source categories and geographic areas. 

Figure 7.4-4. CMAQ projections of visibility responses on 20% worst days at Swanquarter 

to 30% reductions from a 2009 inventory for visibility-reducing pollutants in different 

source categories and geographic areas. 

Linville Gorge, NC (20% Worst Days)

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

SO2_EGU

SO2_nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL

Linville Gorge, NC (20% Worst Days)

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

-16.00

-14.00

-12.00

-10.00

-8.00

-6.00

-4.00

-2.00

0.00

2.00

SO2_EGU

SO2_nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL

Swanquarter, NC (20% Worst Days)

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

SO2_EGU

SO2_nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL

Swanquarter, NC (20% Worst Days)

-6.00

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

SO2_EGU

SO2_nonEGU

NOx_Ground

NOx_Point

NH3

VOCs

PC_Ground

PC_Point

PC_Fires

Δ

Bext (Mm-1)

Bio VOC

Anthro VOC

BCs

MRPO

M-VU

CEN

VISTAS

WV

VA

TN

SC

NC

MS

KY

GA

FL

AL
Regional Haze SIP 65 

for North Carolina Class I Areas December 17, 2007 

As Figures 7.4-1 through 7.4-4 illustrate, the greatest visibility benefits on the 20% worst days 

for the North Carolina Class I areas are projected to result from further reducing SO2 from 

EGUs. At the mountain Class I areas, benefits are projected from SO2 reductions from EGUs in 

several VISTAS states including Alabama, Georgia, Kentucky, North Carolina, South Carolina, 

Tennessee, Virginia, and West Virginia. Contributions from other RPOs and from the boundary 

conditions are comparatively small and the greatest benefits would likely be from further EGU 

reductions within the VISTAS states. In contrast, at Swanquarter, reductions from EGUs in 

North Carolina and South Carolina would have the greatest benefits and the contributions from 

other VISTAS states are comparatively small. MANE-VU states also contribute, as do SO2 and 

SO4 coming into the modeling domain from outside the boundary (e.g. Atlantic Ocean). 

Additional, smaller benefits are projected from additional SO2 emission reductions from nonutility, industrial point sources. The pattern of relative SO2 contributions from non-EGUs 

among the various VISTAS states is similar to the pattern of relative SO2 contributions from 

EGUs. 

Because ammonium nitrate is a small contributor to PM2.5 mass and visibility impairment on the 

20% worst days at the mountain Class I areas, the benefits of reducing NOx and NH3 emissions 

at these sites are small. Some of the 20% worst days at Swanquarter, and other coastal sites in 

the VISTAS states, occur in the winter when ammonium nitrate has a somewhat larger 

contribution to visibility impairment. As shown in Figure 7.4-4, reducing ammonia emissions 

would be more beneficial for reducing ammonium nitrate contributions to visibility impairment 

in wintertime than further reducing nitrogen oxide emissions from either ground or point sources. 

For Swanquarter, the numerous hog farms in eastern North Carolina are the likely primary 

emission sources for ammonia. 

VOC emissions do contribute to visibility impairment, but as shown in the charts above, this 

contribution is from biogenic sources such as vegetative emissions. Controlling anthropogenic 

sources of VOC emissions has little if any visibility benefit at the Class I areas. Reducing 

primary carbon from point sources, ground level sources or fires are projected to have small to 

no visibility benefit. This is consistent with the monitoring data that shows that most of 

measured organic carbon is secondary in origin and primary carbon is only a small fraction of the 

total measured carbon (Appendix B). The sensitivities were not useful in analyzing reductions 

carbon from fires because there was little fire activity at these sites on the days modeled. 

However, looking at the 2000 – 2004 reconstructed extinction, using the new IMPROVE 

equation, for the 20% worst days it is clear that the number of days where fires played a role in 

visibility impairment was approximately 2% to 3% of the days in the entire baseline period (see 

Appendix B). Therefore, although the emission reduction sensitivities did not include many days 

influenced by fires, this should not impact the ultimate results of the sensitivities. 

Note that these results from the emission sensitivity runs are consistent with the conclusions 

drawn from the 2000-2004 baseline monitoring data (see Section 2.4). The results indicate that 

sulfate is the dominant contributor to visibility impairment on the 20% worst days at all sites, 

and that ammonium nitrate may be important for sites where the 20% worst days occur in the 

winter. The NCDAQ concluded that reducing SO2 emissions from EGU and non-EGU point 

sources in the VISTAS states would have the greatest visibility benefits for the North Carolina 

Class I areas. Contributions from the Midwest RPO and MANE-VU are greater at the Class I 
Regional Haze SIP 66 

for North Carolina Class I Areas December 17, 2007 

areas bordering these RPOs. Contributions from outside the VISTAS 12-km modeling domain 

are more important for the coastal Class I areas. These results are consistent with the CMAQ 

model results indicating that contributions from international emissions to visibility impairment 

at VISTAS Class I areas are greater closer to the boundaries of the modeling domain (see 

summary in Section 7.3 and further discussion in Appendix H). 

7.5 What Control Determinations Represent Best Available Retrofit Technology for 

Individual Sources? 

Section 169A of the CAA directs States to assess certain large emission sources for additional 

controls in order to address visibility impacts. States are directed to conduct BART 

determinations for such sources in specific source categories, and which contribute to visibility 

impairment in Class I areas. The 1999 regional haze rule includes the BART requirement, and 

directs States to include BART in their regional haze SIPs. On July 6, 2005, the USEPA 

published a revised final rule, including Appendix Y to 40 CFR Part 51, the Guidelines for BART 

Determinations Under the Regional Haze Rule (hereinafter referred to as the “BART 

Guidelines”) that provides guidance to states on determining which of these sources should be 

subject to BART, and how to determine BART for each source. 

A BART-eligible source is one which has the potential to emit 250 tons or more of a visibilityimpairing air pollutant, was put in place between August 7, 1962 and August 7, 1977, and whose 

operations fall within one or more of 26 specifically listed source categories. Under the CAA, a 

BART determination is required for any BART-eligible source that a State determines ‘‘emits 

any air pollutant which may reasonably be anticipated to cause or contribute to any impairment 

of visibility in any such area.’’ 

For those sources subject to BART, Section 169A(g)(7) of the CAA requires that States must 

consider the following factors in making BART determinations: (1) the costs of compliance, (2) 

the energy and non-air quality environmental impacts of compliance, (3) any existing pollution 

control technology in use at the source, (4) the remaining useful life of the source, and (5) the 

degree of improvement in visibility which may reasonably be anticipated to result from the use 

of such technology. 

7.5.1 BART-Eligible Sources in North Carolina 

The following is a list of facilities with BART-eligible sources in North Carolina. See 

Appendix L for a detailed description of each BART-eligible emission unit: 

• Alcoa, Inc.-Badin Works 

• Blue Ridge Paper Products – Canton Mill 

• DAK Americas – Cape Fear 

• DAK Americas – Cedar Creek 

• Duke Energy – Belews Creek Steam Station 

• Duke Energy – Cliffside Steam Station 

• Duke Energy – Marshall Steam Station 

• Elementis Chromium 

• International Paper – Riegelwood Mill 
Regional Haze SIP 67 

for North Carolina Class I Areas December 17, 2007 

• International Paper – Roanoke Rapids 

• Invista, S.A.R.L. 

• PCS Phosphate Company Inc. – Aurora 

• Progress Energy – Asheville Plant 

• Progress Energy – Roxboro Steam Electric Plant 

• Progress Energy – Sutton Plant 

• Weyerhaeuser Company – Plymouth 

• Weyerhaeuser Company – New Bern 

The BART-eligible sources were identified using the methodology in the BART Guidelines. 

• One or more emissions units at the facility fit within one of the 26 categories listed in the 

BART Guidelines; 

• The emission unit(s) were in existence on August 7, 1977 and began operation at some 

point on or after August 7, 1962; and 

• The potential emissions considering enforceable limits from all emission units identified 

in the previous two bullets emission units were 250 tons or more per year of any of these 

visibility-impairing pollutants: SO2, NOx, and PM10. 

The BART Guidelines recommend addressing these visibility-impairing pollutants: SO2, NOx, 

and particulate matter, and suggest that States use their best judgment in determining whether to 

address VOC or ammonia emissions. The NCDAQ addressed SO2 and NOx, and used 

particulate matter less than 10 microns in diameter (PM10) as an indicator for particulate matter 

to identify BART-eligible units, as the BART Guidelines recommend. As discussed in detail in 

Appendix L, VISTAS modeling demonstrated that VOCs and ammonia from point sources are 

not visibility-impairing pollutants. For this reason, the NCDAQ did not evaluate emissions of 

VOCs and ammonia in BART determinations. 

7.5.2 Determination of Sources Subject to BART in North Carolina 

Under the BART Guidelines, the NCDAQ may consider exempting some sources from BART if 

it is determined that they do not cause or contribute to visibility impairment in a Class I area. In 

accordance with the BART guidelines, the NCDAQ chose to perform source-specific analyses to 

determine which sources cause or contribute to visibility impairment using the CALPUFF 

model. The CALPUFF modeling protocol used for determining which facilities are subject to 

BART is included in Appendix L. In accordance with the Guidelines, a contribution threshold of 

0.5 dv was used for determining which sources were subject to BART. Detailed discussions 

about how a threshold of 0.5 dv meets the USEPA’s BART guidelines can be found in 

Appendix L. 

All of North Carolina’s BART-eligible sources submitted exemption-modeling demonstrations. 

Fifteen of the seventeen sources were able to demonstrate exemption. Results of these 

demonstrations are summarized in Tables 7.5.2-1 through 7.5.2-3 below. Additional details are 

available in Appendix L. Facilities found to be subject to BART must complete a BART 

analysis. 
Regional Haze SIP 68 

for North Carolina Class I Areas December 17, 2007 

Table 7.5.2-1 represents the facilities that were able to demonstrate exemption from BART based 

on CALPUFF modeling conducted using the VISTAS modeling protocol and the old IMPROVE 

equation. Table 7.5.2-2 represents the facilities that were able to demonstrate exemption from 

BART based on CALPUFF modeling conducted using the VISTAS modeling protocol and the 

new IMPROVE equation. Refer to Appendix B for a discussion on the old and new IMPROVE 

equations. The NCDAQ has proposed to exempt all of the units listed in these two tables and no 

significant adverse comments were received during the public comment periods. For further 

details about the BART exemption modeling, please refer to Appendix L. 

Table 7.5.2-1. BART Exemption Modeling Results for Sources using Old IMPROVE 

Equation 

Facility Class 1 Areas Distance To 

Class I Area (km) 

Impact 

(Change in dv)

 Linville Gorge 164 0.260 

 James River Face 242 0.175 

 Cape Romain 265 0.135 

 Great Smoky Mountains 264 0.113 

ALCOA – Badin 

(for SO2, NOx and PM10) 

 Shining Rock 241 0.109 

 DAK Americas - Cape Fear Swanquarter 187 0.19 

(for SO2, NOx and PM10) Cape Romain 182 0.16 

 Swanquarter 219 0.08 

 Cape Romain 216 0.06 

 Linville Gorge 295 0.05 

 DAK Americas - Cedar Creek 

(for SO2, NOx and PM10) 

 James River Face 291 0.04 

 Elementis Chromium Swanquarter 170 0.185 

(for SO2, NOx and PM10) Cape Romain 200 0.129 

 Swanquarter 210 0.112 International Paper - 

Riegelwood 

(for SO2, NOx and PM10) Cape Romain 150 0.109 

 Swanquarter 164 0.305 

 Shenandoah 204 0.248 

 International Paper - Roanoke 

Rapids 

(for SO2, NOx and PM10) James River Face 200 0.234 

 Invista, S.A.R.L. Swanquarter 184 0.286 

(for SO2, NOx and PM10) Cape Romain 187 0.215 

 Shining Rock 26 0.372 

 Great Smoky Mountains 50 0.265 

 Linville Gorge 68 0.143 

 Joyce Kilmer-Slickrock 125 0.042 

 Progress Energy – Asheville 

(for PM10) 

 Cohutta 185 0.031 

Progress Energy – Sutton Swanquarter 185 0.156 

(for PM10) Cape Romain 183 0.148 

 Swanquarter 73 0.336 

 Shenandoah 300 0.087 Weyerhaeuser – Plymouth 

(for SO2, NOx and PM10) James River Face 300 0.068 
Regional Haze SIP 69 

for North Carolina Class I Areas December 17, 2007 

Table 7.5.2-2. BART Exemption Modeling Results for Sources using New IMPROVE 

Equation 

Facility Class 1 Areas Distance To 

Class I Area (km) 

Impact 

(Change in dv)

 Linville Gorge 180 0.26 

 James River Face 140 0.24 

 Shenandoah 215 0.20 

 Great Smoky Mountains 290 0.09 

 Shining Rock 280 0.09 

 Duke Energy Belews Creek 

(for PM10) 

 Otter Creek 290 0.06 

 Linville Gorge 60 0.25 

 Shining Rock 105 0.13 

 Great Smoky Mountains 130 0.09 

 Cohutta 265 0.05 

Duke Energy Cliffside 

(for PM10) 

 Joyce Kilmer-Slickrock 205 0.05 

 Linville Gorge 95 0.46 

 James River Face 240 0.15 

 Shining Rock 180 0.15 

 Great Smoky Mountains 200 0.11 

Duke Energy Marshall 

(for PM10) 

 Joyce Kilmer-Slickrock 280 0.07 

 James River Face 113 0.483 

 Shenandoah 168 0.304 

 Linville Gorge 257 0.214 

 Swanquarter 264 0.152 

 Dolly Sodds 265 0.069 

Progress Energy – Roxboro 

(for PM10) 

 Otter Creek 262 0.066 

 Weyerhaeuser – New Bern 

(for SO2, NOx and PM10) Swanquarter 65 0.3671

1

Initial modeling showed an impact of 0.722 dv at Swanquarter. Initial modeling showed an impact of 0.211 dv 

at Cape Romain (300 km from facility). Since the initial modeling result was below the 0.5 dv contribution 

threshold, Cape Romain was not evaluated in Weyerhaeuser’s revised modeling.

There were two sources that failed to model below the 0.5 dv threshold for exemption. These 

facilities were PCS Phosphate and Blue Ridge Paper. The exemption modeling results are listed 

in Table 7.5.2-3. For the exemption modeling, both sources were required to model for SO2, 

NOx and PM10. PCS Phosphate used the new IMPROVE equation for their modeling; whereas 

Blue Ridge Paper used the old IMPROVE equation. 
Regional Haze SIP 70 

for North Carolina Class I Areas December 17, 2007 

Table 7.5.2-3. Exemption Modeling Results for BART-Subject Sources. 

Facility Class 1 Areas Distance To 

Class I Area (km) 

Impact 

(Change in dv)

 PCS Phosphate Swanquarter 32 1.319 

Shining Rock 11 2.887 

 Great Smoky Mountains 22 0.764 

 Linville Gorge 89 0.155 

 Joyce Kilmer-Slickrock 99 0.134 

Blue Ridge Paper 

 Cohutta 161 0.095 

Six of North Carolina’s BART-eligible sources are EGUs subject to the North Carolina CSA. 

Under the Act, Duke Energy and Progress Energy must reduce their NOx emissions by 77 

percent by 2009 and SO2 emissions by 73 percent by 2013. These sources have already installed 

or are installing scrubbers to reduce SO2 emissions and to reduce NOx emissions Selective 

Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR). The EGUs are 

required by the statute to submit annual update to their compliance plans to meet these 

requirements. The Duke Energy and Progress Energy compliance plans from the June 1, 2007 

report Implementation of the Clean Smokestacks Act summarize the status of control on these 

EGUs and are attached to Appendix L. 

The USEPA has determined that, as a whole, the CAIR cap-and-trade program improves 

visibility more than implementing BART for individual sources in states affected by CAIR. A 

State that opts to participate in the CAIR program under 40 CFR 96.201-.224 (Subpart AAA 

through EEE) need not require BART-eligible EGUs subject to CAIR to install, operate, and 

maintain BART for SO2 or NOx emissions. Given that all BART-eligible units are installing 

scrubbers and NOx controls, and since North Carolina is participating in CAIR and accepts the 

USEPA’s overall finding that CAIR “substitutes” for BART for NOx and SO2, North Carolina’s 

EGUs were allowed to submit BART exemption modeling demonstrations for PM emissions 

only. All six EGUs demonstrated that they do not contribute to visibility impairment in any 

Class I area. 

In total, fifteen of North Carolina’s seventeen BART-eligible sources were able to demonstrate 

that they did not cause or contribute to visibility impairment in any Class I area within 300 km of 

the source. Six sources used the new IMPROVE equation in efforts to demonstrate exemption. 

7.5.3 Determination of BART Requirements for Subject-to-BART Sources 

Two sources, PCS Phosphate in Aurora, North Carolina and Blue Ridge Paper in Canton, North 

Carolina, were unable to demonstrate a contribution of less than 0.5 dv at all Class I areas within 

300 km from their BART-eligible sources. These two facilities are considered to be “subject to 

BART” and were required to submit permit applications containing their evaluation of potential 

BART options and proposed BART determinations. These facilities submitted permit 

applications including their proposed BART determinations in the Fall of 2006. The proposed 

BART determinations have been reviewed by the NCDAQ and it was determined that BART is 

no additional controls at either facility. The BART determinations will be taken to public 
Regional Haze SIP 71 

for North Carolina Class I Areas December 17, 2007 

hearing concurrent with the public hearing on the Regional Haze SIP. Permit issuance is 

targeted for the fall of 2007. For a more detailed discussion of the BART determinations, please 

see Appendix L. 

7.6 Relative Contributions to Visibility Impairment: Geographic Areas of Influence for 

North Carolina Class I Areas 

Once it was determined that SO2 emission reductions from EGU and non-EGU point sources in 

the VISTAS states would be the most effective sources to control to improve visibility at the 

North Carolina Class I areas, the next step was to identify the specific geographic areas that most 

likely influence visibility in each Class I area, and then to identify the major SO2 point sources 

located in those geographic areas. An SO2 Area of Influence was defined for each Class I area 

to represent the geographic area containing sources that would likely have the greatest impact on 

visibility at that Class I area. All SO2 point sources within these Areas of Influence were 

identified and ranked by their 2018 emissions. The following sections contain a broad overview 

of the steps in the Area of Influence analyses. See Appendix H for a more detailed discussion of 

these analyses and plots for additional Class I areas. 

7.6.1 Back Trajectory Analyses 

The first step was to generate meteorological back trajectories for IMPROVE monitoring sites in 

North Carolina and neighboring Class I areas for the 2000-2004 20% worst days baseline period. 

Back trajectory analyses use interpolated measured or modeled meteorological fields to estimate 

the most likely central path of air masses that arrive at a receptor at a given time. The method 

essentially follows a parcel of air backward in hourly steps for a specified length of time. Figure 

7.6.1 is an example of a back trajectory analysis for Great Smoky Mountains National Park for 

the 20% worst days in 2002. 

Figure 7.6.1. Example back trajectories for 20% worst visibility days in 2002 for Great 

Smoky Mountains. 
Regional Haze SIP 72 

for North Carolina Class I Areas December 17, 2007 

Trajectories were started at 100 meters and 500 meters above the surface and run backward from 

the site for 72-hours. These individual back trajectories for 20% worst days in 2002 were also 

useful in evaluating model performance for individual days at the Class I areas. 

7.6.2 Residence Time Plots 

The next step was to plot residence time for each Class I area using five years of back trajectories 

for the 20% worst visibility days in 2000-2004. Residence time is the frequency that winds pass 

over a specific geographic area on the path to a Class I area. Separate residence time plots were 

generated using trajectories with 100m and 500m start heights. As illustrated in Figure 7.6.2-1, 

winds influencing Great Smoky Mountains on the 20% worst days come from all directions and 

there is no single predominant wind direction influencing the 20% worst visibility days. In 

contrast, at Swanquarter, the residence time plot indicates a clear north-south gradient of 

influence along the eastern coast of the United States (Figure 7.6.2-2). The residence time plots 

for the other Class I areas can be found in Appendix B. 

Figure 7.6.2-1. Example residence time plot for 20% worst visibility days in 2000-2004 for 

Great Smoky Mountains based on trajectories with 100m start height. 

GRSM1

2000-04

20% Worst Monitored Days

100m Residence Times (%)

< 0.01

0.01 - 0.02

0.02 - 0.04

0.04 - 0.08

0.08 - 0.16

0.16 - 0.32

> 0.32
Regional Haze SIP 73 

for North Carolina Class I Areas December 17, 2007 

Figure 7.6.2-2. Example residence time plot for 20% worst visibility days in 2000-2004 for 

Swanquarter based on trajectories with 100m start height. 

7.6.3 SO2 Areas of Influence 

As discussed earlier, the NCDAQ has determined that reductions in SO2 emissions would have 

the greatest visibility impact. Therefore, sulfate extinction-weighted residence time plots were 

developed to define the geographic area with highest probability of influencing the receptor on 

the 20% worst days in the 2000-2004 baseline period that were dominated by sulfate. Each back 

trajectory was weighted by sulfate extinction for that day. This allows the focus to be on the 

20% worst days that are influenced by sulfate and places less importance on days influenced by 

organic carbon from fires. Sulfate-weighted back trajectories for the 20% worst days were 

combined for 5 years of data. The resulting sulfate extinction-weighted residence time plots 

were used to define the geographic Area of Influence for sources of SO2 emissions. In Figure 

7.6.3-1 the area representing 10% or greater residence time is outlined in red and the area 

representing 5% or greater residence time is outlined in gray. 

The VISTAS states discussed various options as to what percentage of sulfate extinctionweighted area of influence should be assessed. It was determined that for this planning period 

that the area of influence defined by 5% or greater sulfate extinction-weighted residence time 

provided a reasonable universe of sources that may cause visibility impairment at a Class I area. 

The VISTAS states recognized that this did not represent 100% of the sources contributing to 

visibility impairment at Class I areas, but rather a reasonable universe of sources to consider 

during the first planning period. 
Regional Haze SIP 74 

for North Carolina Class I Areas December 17, 2007 

Figure 7.6.3-1. Example SO2 Area of Influence plot for sulfate extinction weighted 

residence time for 20% worst visibility days in 2000-2004 for Great Smoky Mountains 

based on trajectories with 100m start height. 

7.6.4 Emissions Sources within SO2 Areas of Influence 

Residence time plots were then combined with geographically-gridded emission data based on 

the 2002 baseline and 2018 emissions inventories. Plots were generated for the Areas of 

Influence defined by trajectories with 100m and 500 m start heights. As a way of incorporating 

the effects of transport, deposition, and chemical transformation of point source emissions along 

the path of the trajectories, these data were weighted by 1/d, where d was calculated as the 

distance, in kilometers, between the center of the grid cell in which a source is located and the 

center of the grid cell in which the IMPROVE monitor is located. The distance-weighted point 

source SO2 emissions are then combined with the gridded sulfate extinction-weighted residence 

times at a spatial resolution of 36-km. 

The final step was to combine the residence times and gridded emissions data in plots and data 

sets. The distance weighted (1/d) gridded point source SO2 emissions were multiplied by the 

total sulfate extinction-weighted back-trajectory residence times on a grid cell by grid cell basis. 

These results were then normalized by the domain-wide total and displayed as a percentage. The 

analysis was done using both the 2002 and 2018 emissions inventories. 

SO2 Area of Influence for Great Smoky Mountains

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

SO2 Area of Influence for Great Smoky Mountains

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%

Orange line perimeter indicate Area of Influence with Residence Time > 5%.
Regional Haze SIP 75 

for North Carolina Class I Areas December 17, 2007 

Figures 7.6.4-1 illustrates the 2002 and 2018 distance weighted gridded emissions multiplied by 

sulfate extinction-weighted residence time for Great Smoky Mountains National Park. These 

maps help visualize where the emissions reductions will be occurring between 2002 and 2018. 

The change in SO2 emissions between 2002 and 2018 can be seen by comparing emissions 

source strengths in the two plots. Note the emissions from each source are normalized by the 

total emissions in the domain. Sources that reduce SO2 emissions by 2018 will show a lower 

contribution to emissions in the domain. On the 2018, map the grid cells with these sources will 

show a lighter color gradient than on the 2002 map. For example, SO2 reductions from EGU in 

western and central North Carolina under the North Carolina CSA can be seen by comparing the 

2002 and 2018 maps. Because the total emissions in the domain are smaller in 2018, a source 

that does not change emissions between 2002 and 2018 may actually appear to increase in 

importance in 2018 compared to 2002. 

Although the sulfate extinction-weighted residence times were developed using the 2002 

emissions, the 2018 emissions weighted by residence time plots still provides useful information. 

The NCDAQ does not believe that the area of influence would have changed significantly if 

sulfate extinction-weighted residence times were developed using the 2018 emissions. However, 

if the area of influence would have been smaller using the 2018 emissions due to reductions 

expected in the EGU source sector, then the area developed to identify potential sources would 

be considered conservative. 

Figure 7.6.4-1. Great Smoky Mountains 2002 (left) and 2018 (right) SO2 distance weighted 

emissions times SO4 extinction-weighted residence time plots. 

2002 vs 2018 SO2 Emissions weighted by Residence Time

Great Smoky Mtn., TN 

2002 SO2 emissions 2018 SO2 emissions

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

Max Value = 46%

2002 vs 2018 SO2 Emissions weighted by Residence Time

Great Smoky Mtn., TN 

2002 SO2 emissions 2018 SO2 emissions

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

Max Value = 46%

2002 vs 2018 SO2 Emissions weighted by Residence Time

Great Smoky Mtn., TN 

2002 SO2 emissions 2018 SO2 emissions

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

Max Value = 46%
Regional Haze SIP 76 

for North Carolina Class I Areas December 17, 2007 

Figures 7.6.4-2 through 7.6.4.4 illustrate similar plots for 2018 for Linville Gorge, Shining Rock, 

and Swanquarter. Since Joyce Kilmer-Slickrock Wilderness Area does not have its own 

monitor, the plot for Great Smoky Mountains National Park is considered to represent this area. 

These plots illustrate the relative importance of North Carolina sources of SO2 compared to 

sources in neighboring states. Additional analyses, including 2002 and 2018 distance weighted 

emissions times residence-time plots for the Class I areas in North Carolina and neighboring 

states are contained in Appendix H. These analyses are serving as the basis for consultation 

among the VISTAS states. 

Figure 7.6.4-2. Linville Gorge 2018 SO2 distance weighted emissions times SO4 extinctionweighted residence time plot. 

2018 SO2 Emissions weighted by Residence Time - Linville Gorge, NC 

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

2018 SO2 Emissions weighted by Residence Time - Linville Gorge, NC 

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.
Regional Haze SIP 77 

for North Carolina Class I Areas December 17, 2007 

Figure 7.6.4-3. Shining Rock 2018 SO2 distance weighted emissions times SO4 extinctionweighted residence time plot. 

Figure 7.6.4-4. Swanquarter 2018 SO2 distance weighted emissions times SO4 extinctionweighted residence time plot. 

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

2018 SO2 Emissions weighted by Residence Time - Swanquarter, NC

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

2018 SO2 Emissions weighted by Residence Time - Swanquarter, NC

2018 SO2 Emissions weighted by Residence Time - Shining Rock, NC 

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.

2018 SO2 Emissions weighted by Residence Time - Shining Rock, NC 

Green circles indicate 100-km and 200-km radii from Class I area.

Red line perimeter indicate Area of Influence with Residence Time > 10%.

Orange line perimeter indicate Area of Influence with Residence Time > 5%.
Regional Haze SIP 78 

for North Carolina Class I Areas December 17, 2007 

Finally, Table 7.6.4-1 shows, in tabular form, the relative contributions of point source SO2 

emissions from nearby states to North Carolina Class I areas. These percentages were estimated 

by multiplying the maximum residence time to the emissions over distance. 

Table 7.6.4-1 2018 Point Source SO2 Contribution to NC Class I Areas by State

 North Carolina Class I Area 

State GRSM SHRO LIGO SWAN JOKI 

Alabama 3.1% 1.84% 1.35% 6.53% 

Delaware 2.83% 

Florida 2.35% 

Georgia 7.7% 7.22% 1.98% 3.34% 20.46% 

Kentucky 1.0% 0.81% 0.90% 0.10% 1.38% 

Maryland 1.34% 

New Jersey 1.10% 

North Carolina 7.4% 58.84% 34.75% 58.69% 9.08% 

Ohio 0.9% 0.64% 1.76% 

Pennsylvania 0.50% 

South Carolina 2.4% 14.89% 3.93% 15.35% 5.14% 

Tennessee 74.5% 12.19% 36.28% 55.87% 

Virginia 2.3% 2.95% 16.52% 13.78% 1.53% 

West Virginia 0.5% 0.63% 2.52% 0.63% 

Total 100.0% 100.0% 100.0% 100.0% 100.0% 

7.6.5 Specific Source Types in the Areas of Influence for North Carolina Class I Areas 

The next step in the analysis was to review the emissions inventories to determine the source 

categories, as well as specific sources, found to have the greatest impact on visibility in North 

Carolina Class I areas. Lists of SO2 point sources within the Areas of Influence for each Class I 

areas were developed using the VISTAS 2002 base year and 2018 future year emissions. For 

this purpose, the Area of Influence was defined as the counties with maximum sulfate extinction 

weighted residence time greater than five. For SO2 sources within each Area of Influence, the 

following attributes were defined for each individual unit: 

• State, county, and source (plant), and industry identification codes 

• SO2 emissions for 2002 and 2018 

• 2018 control efficiency 

• Distance to Class I areas (defined by distance to the monitor at the Class I area) 

• Emissions divided by distance (Q/d), a metric that accounts for the dispersion of 

emissions over distance 

• Maximum sulfate extinction weighted residence time (RTmax) 

Our review was conducted in a top down fashion starting with an analysis of the major source 

categories in each SO2 Area of Influence to determine which major categories had the highest 
Regional Haze SIP 79 

for North Carolina Class I Areas December 17, 2007 

residual contribution to the area in 2018. It was also important to identify reductions that are 

projected to occur between 2002 and 2018 within each category or at specific units. This 

allowed VISTAS States to determine if certain source categories or units that had yet to be 

controlled under the future year base case had the potential for reduction. Once the highest 

source types were identified, subcategories within those source types were reviewed. The 

contributions from major source categories to the 2018 inventory for the SO2 Areas of Influence 

for the North Carolina Class I areas are listed in Tables 7.6.5-1 through 7.6.5-5. In these tables, 

the source categories are broken out by the USEPA’s Tier 1 report categories and are defined 

below: 

• Fuel Comb Elec Utility Emissions from all fuel combustions at utility boilers 

• Fuel Comb Industrial Emissions from all fuel combustions at industrial boilers 

• Fuel Comb Other Emissions from all fuel combustions from 

commercial/institutional and residential sources (i.e., 

fireplaces, natural gas stoves, oil heaters, etc.) 

• Chemical & Allied Product Mfg Emissions from chemical manufacturing processes 

• Metal Processing Emissions from metal processing operations 

• Petroleum & Related Industries Emissions from petroleum refineries & related industries

• Other Industrial Processes All other industrial processing not previously mentioned 

• Solvent Utilization Emissions from solvent utilization such as degreasing 

operations, surface coating operations, etc. 

• Storage & Transport Emissions from storage and transport of petroleum, 

organic and inorganic products 

• Waste Disposal & Recycling Emissions from open burning, incineration, landfills, 

publicly owned treatment works, treatment storage 

and/or disposal facilities, wastewater treatment facilities 

• Highway Vehicles Emissions from on-road mobile sources 

• Off-highway Emissions from off-road mobile sources 

• Miscellaneous (Ag, Fires) Emissions from agricultural operations, wildland fires, 

and other emissions sources not previously mentioned 
Regional Haze SIP 80 

for North Carolina Class I Areas December 17, 2007 

Table 7.6.5-1. 2018 Emissions Contributions from Major Source Categories in the Area of 

Influence for Great Smoky Mountains. 

Table 7.6.5-2. 2018 Emissions Contributions from Major Source Categories in the Area of 

Influence for Joyce Kilmer, North Carolina. 

Miscellaneous (Ag, Fires) 1% 1% 5% 0% 59% 26% 86%

Off-highway 11% 18% 35% 1% 2% 4% 0%

Highway Vehicles 18% 25% 48% 0% 2% 2% 11%

Waste Disposal & Recycling 4% 2% 3% 0% 5% 11% 0%

Storage & Transport 6% 0% 0% 0% 0% 1% 0%

Solvent Utilization 44% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 6% 5% 1% 3% 8% 11% 0%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 2% 3% 2% 5% 0%

Chemical & Allied Product Mfg 2% 0% 0% 2% 1% 1% 0%

Fuel Comb. Other 5% 6% 3% 6% 5% 12% 1%

Fuel Comb. Industrial 1% 18% 2% 30% 3% 5% 0%

Fuel Comb. Elec. Util. 0% 22% 1% 54% 11% 21% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 1% 1% 5% 0% 59% 26% 86%

Off-highway 11% 18% 35% 1% 2% 4% 0%

Highway Vehicles 18% 25% 48% 0% 2% 2% 11%

Waste Disposal & Recycling 4% 2% 3% 0% 5% 11% 0%

Storage & Transport 6% 0% 0% 0% 0% 1% 0%

Solvent Utilization 44% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 6% 5% 1% 3% 8% 11% 0%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 2% 3% 2% 5% 0%

Chemical & Allied Product Mfg 2% 0% 0% 2% 1% 1% 0%

Fuel Comb. Other 5% 6% 3% 6% 5% 12% 1%

Fuel Comb. Industrial 1% 18% 2% 30% 3% 5% 0%

Fuel Comb. Elec. Util. 0% 22% 1% 54% 11% 21% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 1% 1% 5% 0% 61% 28% 85%

Off-highway 11% 18% 35% 1% 2% 4% 0%

Highway Vehicles 18% 26% 48% 1% 2% 2% 12%

Waste Disposal & Recycling 4% 2% 4% 1% 5% 12% 0%

Storage & Transport 6% 0% 0% 0% 0% 1% 0%

Solvent Utilization 44% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 6% 5% 1% 3% 9% 11% 1%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 1% 3% 2% 5% 0%

Chemical & Allied Product Mfg 2% 0% 0% 3% 1% 1% 0%

Fuel Comb. Other 5% 6% 3% 7% 5% 12% 1%

Fuel Comb. Industrial 1% 18% 2% 30% 3% 5% 0%

Fuel Comb. Elec. Util. 0% 21% 1% 51% 9% 17% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 1% 1% 5% 0% 61% 28% 85%

Off-highway 11% 18% 35% 1% 2% 4% 0%

Highway Vehicles 18% 26% 48% 1% 2% 2% 12%

Waste Disposal & Recycling 4% 2% 4% 1% 5% 12% 0%

Storage & Transport 6% 0% 0% 0% 0% 1% 0%

Solvent Utilization 44% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 6% 5% 1% 3% 9% 11% 1%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 1% 3% 2% 5% 0%

Chemical & Allied Product Mfg 2% 0% 0% 3% 1% 1% 0%

Fuel Comb. Other 5% 6% 3% 7% 5% 12% 1%

Fuel Comb. Industrial 1% 18% 2% 30% 3% 5% 0%

Fuel Comb. Elec. Util. 0% 21% 1% 51% 9% 17% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3
Regional Haze SIP 81 

for North Carolina Class I Areas December 17, 2007 

Table 7.6.5-3. 2018 Emissions Contributions from Major Source Categories in the Area of 

Influence for Linville Gorge, North Carolina. 

Table 7.6.5-4. 2018 Emissions Contributions from Major Source Categories in the Area of 

Influence for Shining Rock, North Carolina. 

Miscellaneous (Ag, Fires) 1% 1% 5% 0% 60% 28% 85%

Off-highway 11% 18% 34% 1% 2% 4% 0%

Highway Vehicles 18% 25% 48% 0% 2% 2% 11%

Waste Disposal & Recycling 4% 2% 3% 0% 5% 11% 0%

Storage & Transport 6% 0% 0% 0% 1% 1% 0%

Solvent Utilization 43% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 6% 6% 1% 4% 9% 11% 1%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 2% 3% 2% 5% 0%

Chemical & Allied Product Mfg 2% 1% 0% 2% 1% 1% 1%

Fuel Comb. Other 5% 6% 3% 5% 5% 11% 1%

Fuel Comb. Industrial 1% 19% 2% 31% 3% 6% 0%

Fuel Comb. Elec. Util. 0% 21% 1% 52% 10% 19% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 1% 1% 5% 0% 60% 28% 85%

Off-highway 11% 18% 34% 1% 2% 4% 0%

Highway Vehicles 18% 25% 48% 0% 2% 2% 11%

Waste Disposal & Recycling 4% 2% 3% 0% 5% 11% 0%

Storage & Transport 6% 0% 0% 0% 1% 1% 0%

Solvent Utilization 43% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 6% 6% 1% 4% 9% 11% 1%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 2% 3% 2% 5% 0%

Chemical & Allied Product Mfg 2% 1% 0% 2% 1% 1% 1%

Fuel Comb. Other 5% 6% 3% 5% 5% 11% 1%

Fuel Comb. Industrial 1% 19% 2% 31% 3% 6% 0%

Fuel Comb. Elec. Util. 0% 21% 1% 52% 10% 19% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 1% 1% 4% 0% 57% 24% 85%

Off-highway 11% 19% 36% 0% 2% 5% 0%

Highway Vehicles 19% 26% 49% 0% 2% 2% 11%

Waste Disposal & Recycling 4% 2% 3% 0% 5% 10% 0%

Storage & Transport 6% 0% 0% 0% 1% 1% 0%

Solvent Utilization 44% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 5% 5% 0% 4% 9% 11% 1%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 1% 3% 1% 3% 0%

Chemical & Allied Product Mfg 2% 0% 0% 1% 1% 1% 0%

Fuel Comb. Other 6% 7% 4% 5% 6% 13% 1%

Fuel Comb. Industrial 1% 19% 2% 31% 4% 6% 0%

Fuel Comb. Elec. Util. 0% 20% 1% 54% 13% 23% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 1% 1% 4% 0% 57% 24% 85%

Off-highway 11% 19% 36% 0% 2% 5% 0%

Highway Vehicles 19% 26% 49% 0% 2% 2% 11%

Waste Disposal & Recycling 4% 2% 3% 0% 5% 10% 0%

Storage & Transport 6% 0% 0% 0% 1% 1% 0%

Solvent Utilization 44% 1% 0% 0% 0% 1% 0%

Other Industrial Processes 5% 5% 0% 4% 9% 11% 1%

Petroleum & Related Industries 0% 0% 0% 1% 0% 0% 0%

Metals Processing 1% 1% 1% 3% 1% 3% 0%

Chemical & Allied Product Mfg 2% 0% 0% 1% 1% 1% 0%

Fuel Comb. Other 6% 7% 4% 5% 6% 13% 1%

Fuel Comb. Industrial 1% 19% 2% 31% 4% 6% 0%

Fuel Comb. Elec. Util. 0% 20% 1% 54% 13% 23% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3
Regional Haze SIP 82 

for North Carolina Class I Areas December 17, 2007 

 Table 7.6.5-5. 2018 Emissions Contributions from Major Source Categories in the Area of 

Influence for Swanquarter, North Carolina. 

These tables indicate that for all North Carolina Class I areas, EGUs and industrial boilers are the 

two major sources categories contributing to 2018 SO2 emissions in the Areas of Influence, even 

after implementation of the CSA and CAIR. Together these two source categories contribute 79-

85 percent of the 2018 SO2 emissions for the Areas of Influence for the North Carolina Class I 

areas. Other fuel combustion and other industrial processes comprise another 9-12 percent of the 

2018 SO2 emissions. 

These tables can also be used to evaluate the major source categories contributing to emissions 

of NOx, NH3, and PM emissions in 2018. For instance, highway vehicles and off road vehicles 

are major sources of NOx emissions, in addition to electric utilities and industrial boilers. The 

source category “miscellaneous” (which includes agricultural sources and fires) is the major 

contributor to NH3 and primary PM. However, based upon the 2000 – 2004 reconstructed 

extinction for the 20% worst visibility days (Appendix B), these pollutants are not significant 

contributors to visibility impairment on most days in the baseline period. Additionally, the 

emissions sensitivities discussed in Section 7.4 indicated very small benefits of controlling NOx, 

NH3, and primary PM emissions at the North Carolina Class I areas, but if these emissions were 

of concern, different source categories would need to be addressed. 

The contributions to SO2 emissions in 2018 from the three highest source categories, electric 

utilities, industrial boilers, and other fuel combustion have been further broken out into 

subcategories. Table 7.6.5-6 indicates subcategories for the Areas of Influence for the North 

Carolina Class I areas. Within electric utilities, all the SO2 emissions are attributable to coalfired power plants. Within industrial boilers, most emissions are attributable to coal-fired boilers 

with lesser contributions from oil and gas boilers. Commercial and institutional coal and oil 

boilers have smaller contributions. 

Miscellaneous (Ag, Fires) 2% 1% 7% 0% 61% 32% 85%

Off-highway 16% 20% 37% 1% 3% 6% 0%

Highway Vehicles 19% 23% 43% 1% 2% 2% 11%

Waste Disposal & Recycling 4% 3% 5% 1% 6% 13% 0%

Storage & Transport 7% 0% 0% 0% 1% 1% 0%

Solvent Utilization 38% 0% 0% 0% 0% 0% 0%

Other Industrial Processes 5% 6% 1% 5% 8% 10% 1%

Petroleum & Related Industries 0% 0% 0% 0% 0% 0% 0%

Metals Processing 0% 1% 2% 3% 1% 1% 0%

Chemical & Allied Product Mfg 1% 1% 0% 2% 0% 1% 1%

Fuel Comb. Other 5% 7% 3% 7% 5% 10% 1%

Fuel Comb. Industrial 1% 16% 2% 29% 4% 5% 0%

Fuel Comb. Elec. Util. 0% 21% 1% 50% 10% 19% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3

Miscellaneous (Ag, Fires) 2% 1% 7% 0% 61% 32% 85%

Off-highway 16% 20% 37% 1% 3% 6% 0%

Highway Vehicles 19% 23% 43% 1% 2% 2% 11%

Waste Disposal & Recycling 4% 3% 5% 1% 6% 13% 0%

Storage & Transport 7% 0% 0% 0% 1% 1% 0%

Solvent Utilization 38% 0% 0% 0% 0% 0% 0%

Other Industrial Processes 5% 6% 1% 5% 8% 10% 1%

Petroleum & Related Industries 0% 0% 0% 0% 0% 0% 0%

Metals Processing 0% 1% 2% 3% 1% 1% 0%

Chemical & Allied Product Mfg 1% 1% 0% 2% 0% 1% 1%

Fuel Comb. Other 5% 7% 3% 7% 5% 10% 1%

Fuel Comb. Industrial 1% 16% 2% 29% 4% 5% 0%

Fuel Comb. Elec. Util. 0% 21% 1% 50% 10% 19% 1%

Tier VOC NOX CO SO2 PM-10 PM-2.5 NH3
Regional Haze SIP 83 

for North Carolina Class I Areas December 17, 2007 

Table 7.6.5-6. 2018 Emissions Contributions from Major Source Categories in the Area of 

Influence for Swanquarter North Carolina. 

From these analyses, the NCDAQ considered what additional control measures for electric 

utilities and industrial boilers are reasonable. The lists of individual sources are also being used 

to determine if individual sources in other sources categories are major contributors to SO2 

emissions in the Areas of Influence. 

7.7 Evaluating the Four Statutory Factors for Specific SO2 Emissions Sources in Each 

Area of Influence 

The next step was to identify emission reductions that have already occurred within each source 

category and at specific units. A list of emission units located within the area of influence for 

each Class I area was compiled using the modeling emissions inventories. Unit level tables of 

emission comparisons from 2002 to 2018 were developed, allowing VISTAS States to review 

existing emission reductions. These tables assigned future year control technology from IPM 

forecasting and State modification for EGU and from control efficiency tables for non-EGU 

point sources. These tables can be found in Appendix H. 

Once emission control profiles for specific units were defined, the next step is to determine what, 

if any, additional control measures would be technically feasible, and to assign costs to those 

control measures. For EGUs, the 2018 IPM file used by VISTAS was obtained and matched to 

the 2018 base case inventory of EGU sources. This step was conducted to ensure that 

1%

0%

0%

0%

3%

2%

0%

1%

2%

6%

21%

0%

0%

0%

0%

51%

JOKI

2%

0%

0%

0%

3%

2%

0%

2%

2%

7%

18%

1%

1%

0%

1%

47%

SWAN

1%

0%

0%

0%

2%

2%

0%

1%

2%

4%

25%

0%

0%

0%

0%

53%

LIGO

1%

0%

0%

0%

3%

2%

0%

1%

2%

5%

24%

0%

0%

0%

0%

52%

SHRO

Fuel Comb. Other-Residential Other 1%

Fuel Comb. Other-Residential Wood 0%

Fuel Comb. Other-Misc. (Except Residential) 0%

Fuel Comb. Other-Comm/Institutional Gas 0%

Fuel Comb. Other-Comm/Institutional Oil 3%

Fuel Comb. Other-Comm/Institutional Coal 2%

Fuel Comb. Industrial-Internal Combustion 0%

Fuel Comb. Industrial-Other 1%

Fuel Comb. Industrial-Gas 2%

Fuel Comb. Industrial-Oil 5%

Fuel Comb. Industrial-Coal 22%

Fuel Comb. Elec. Util.-Internal Combustion 0%

Fuel Comb. Elec. Util.-Other 0%

Fuel Comb. Elec. Util.-Gas 0%

Fuel Comb. Elec. Util.-Oil 0%

Fuel Comb. Elec. Util.-Coal 54%

Tier GRSM

1%

0%

0%

0%

3%

2%

0%

1%

2%

6%

21%

0%

0%

0%

0%

51%

JOKI

2%

0%

0%

0%

3%

2%

0%

2%

2%

7%

18%

1%

1%

0%

1%

47%

SWAN

1%

0%

0%

0%

2%

2%

0%

1%

2%

4%

25%

0%

0%

0%

0%

53%

LIGO

1%

0%

0%

0%

3%

2%

0%

1%

2%

5%

24%

0%

0%

0%

0%

52%

SHRO

Fuel Comb. Other-Residential Other 1%

Fuel Comb. Other-Residential Wood 0%

Fuel Comb. Other-Misc. (Except Residential) 0%

Fuel Comb. Other-Comm/Institutional Gas 0%

Fuel Comb. Other-Comm/Institutional Oil 3%

Fuel Comb. Other-Comm/Institutional Coal 2%

Fuel Comb. Industrial-Internal Combustion 0%

Fuel Comb. Industrial-Other 1%

Fuel Comb. Industrial-Gas 2%

Fuel Comb. Industrial-Oil 5%

Fuel Comb. Industrial-Coal 22%

Fuel Comb. Elec. Util.-Internal Combustion 0%

Fuel Comb. Elec. Util.-Other 0%

Fuel Comb. Elec. Util.-Gas 0%

Fuel Comb. Elec. Util.-Oil 0%

Fuel Comb. Elec. Util.-Coal 54%

Tier GRSM
Regional Haze SIP 84 

for North Carolina Class I Areas December 17, 2007 

incremental controls assigned to these source types did not duplicate existing base case 

assumptions. 

VISTAS used the USEPA’s AirControlNET database, modified for the VISTAS emission 

inventories, for the non-EGUs. The core of AirControlNET is a relational database system in 

which control technologies are linked to sources within the USEPA emissions inventories. The 

system contains a database of control measure applicability, efficiency, and cost information for 

reducing emissions. The control measure data file in AirControlNET includes not only the 

technology's control efficiency, and calculated emission reductions for that source, but also 

estimates the costs (annual and capital) for application of the control measure. 

Using the modified inventories identified above, VISTAS ran every available SO2 control 

strategy in AirControlNET against the EGU and non-EGU point source inventories to develop a 

master list of incremental control strategies for each unit in the VISTAS 36 km domain. 

For the sources within the Area of Influences for each North Carolina Class I area, the master list 

of incremental control measures was sorted to determine the costs of incremental control 

measures. These data were combined in a master spreadsheet with the distance from the emission 

release point to the Class I area IMPROVE monitor (in km), the 2018 residual emissions and 

distance (Q/d) or squared distance (Q/d^2), and the normalized 2018 SO2 point source emissions 

times distance-weighted residence time (RTMax) values for the county in which the emission 

release point was located. North Carolina evaluated these control measures and costs as part of 

their review of the statutory factors for reasonable further progress. 

The regional haze rule requires that states consider the following factors and demonstrate how 

these factors were taken into consideration in selecting the reasonable progress goal: 

• the costs of compliance 

• the time necessary for compliance 

• the energy and non-air quality environmental impacts of compliance, and 

• the remaining useful life of any potentially affected sources. 

Cost of Compliance: 

As defined in Section 7.6.5, coal-fired electric utilities and coal-fired industrial boilers were the 

largest source categories contributing to SO2 in 2018 in the Areas of Influence defined for the 

North Carolina Class I areas. Industrial boilers using oil and commercial and institutional boilers 

using coal or oil had small contributions to SO2 in 2018. 

Sulfur dioxide emissions from utility, industrial, commercial, or institutional boilers can be 

controlled either by switching the fuel source to a lower sulfur fuel content or by installing postcombustion controls. Costs vary by fuel source, boiler type and boiler size and require source 

specific analyses for accuracy. 

Bituminous coal is commonly burned in boilers in the eastern US. Switching to another 

bituminous coal with lower sulfur content or blending bituminous coals can reduce SO2 
Regional Haze SIP 85 

for North Carolina Class I Areas December 17, 2007 

emissions with least impact to boiler performance. While sub-bituminous coal has a lower sulfur 

content than bituminous coal, it also has a lower heat content and so more coal has to be burned 

to generate the same energy output. For boilers that are designed for bituminous coal, only a 

small fraction of the fuel can be switched to low sulfur sub-bituminous coal without adversely 

affecting boiler operations. Boiler modifications to accommodate low sulfur sub-bituminous 

coal may not be cost-effective. Contract initiation and termination costs, differential fuel prices 

and heat contents, transportation costs, and modification to boiler operations, fuel handling and 

waste handling systems will have to be considered specific to each source. 

Flue-gas desulfurization is the common post-combustion control for coal-fired boilers. Flue gas 

is passed through an absorbent for sulfur dioxide (generally limestone or lime) in either a wet 

scrubber, dry scrubber, or spray dryer. A calcium sulfate by-product is produced that may be 

further processed to produce gypsum as a commercial byproduct. Costs of flue-gas 

desulfurization include initial capital costs and ongoing operational and maintenance costs for 

the absorber tower, sorbent handling, and waste product handling facilities. Costs per ton of SO2 

removed vary with boiler size, type, and available space for retrofit control devices. 

For oil-fired boilers, lower sulfur oil may be an option. Costs need to consider differential fuel 

prices and heat content, boiler modifications, fuel handling costs, and maintenance costs. 

Conceptually, post-combustion controls can be used for oil boilers, but there is little precedence 

for such installations. 

Time Necessary for Compliance:

For fuel switching, the time necessary to terminate existing fuel contracts and initiate new 

contracts needs to be considered. Generally two to three years may be required. Installation of 

post-combustion controls will require 3 or more years depending on market availability of labor 

and materials and utility system-wide priorities. Time necessary for compliance will need to be 

refined for specific sources. 

Energy and Non-Air Environmental Impacts: 

Switching to lower sulfur fuel or installing post-combustion controls may reduce boiler heat rate 

and energy output. Scrubbers and spray dryers will require additional safeguards for fuel 

handling and waste handling systems to avoid additional non-air environmental impacts such as 

increased effluents in waste water discharges and storm water runoff. These factors will need to 

be considered specific to individual sources. Carbon dioxide is emitted as a by-product of flue 

gas desulfurization, therefore impacts of increased carbon emissions will need to be considered, 

particularly if carbon emissions are limited in the future under climate change mitigation 

strategies. 

Remaining Useful Life: 

The useful remaining life is specific to the unit for which controls are considered. 

7.8 Which Control Measures Represent Reasonable Progress for Individual Sources? 

The following summarizes the process for determining reasonable progress for North Carolina 

sources. For a detailed discussion of the reasonable progress assessments for all units with a 
Regional Haze SIP 86 

for North Carolina Class I Areas December 17, 2007 

contribution of greater than one percent to visibility impairment at any Class I area in North 

Carolina or in neighboring states, please see Appendix H. 

Step 1: Determine pollutants of concern. 

VISTAS evaluated the species contribution on the 20% worst visibility days in the baseline 

period and concluded that sulfate accounted for greater than 70% of the visibility impairing 

pollution. The VISTAS States concluded that controlling SO2 emissions was the appropriate 

step in addressing the reasonable progress assessment for 2018. The VISTAS findings were 

consistent with the findings of SAMI. As you recall, SAMI confirmed that sulfate particles 

account for the greatest portion of the haze affecting Class I areas in the Southern Appalachian 

region and that these sulfates were produced in large part from SO2 emissions from coal 

combustion. 

Step 2: Determine which source sectors should be evaluated for reasonable progress. 

Since the pollutant of primary concern was determined to be SO2, the emissions inventory was 

assessed to determine the source categories that contribute the most SO2 emissions. Point source 

emissions in 2018 are projected to represent greater than 95% of the total SO2 emissions 

inventory, the VISTAS States concluded that the focus should be on electric generating unit 

(EGU) and non-EGU point sources of SO2 emissions. 

Step 3: Determine if the Clean Air Interstate Rule is sufficient for reasonable progress for subject 

EGUs. 

The NCDAQ evaluated the amount of SO2 reduction from the EGU sector resulting from the 

implementation of the North Carolina Clean Smokestacks Act (CSA) and CAIR. The EGUs in 

North Carolina are expected to reduce their SO2 emissions by greater than 80% between 2002 

and 2018. Much of that reduction is the result of CSA requirements which are directly 

enforceable and which must be satisfied by actual emission reductions as opposed to buying 

banked Title IV allowances to meet the system-wide emissions caps. In contrast, the SO2 

emission reductions beyond CSA that are predicted by the IPM to meet the CAIR requirements 

are not as certain due to that rule’s provision for regional emissions trading and the use of 

banked Title IV allowances. 

To further support EGUs subject to CAIR is sufficient for reasonable progress, a discussion in 

the CAIR rule highlighted below (70 FR 25197) addresses the reasonable progress factors of cost 

and time necessary for compliance for these EGUs, and provide the necessary support for a 

State's four factor reasonable progress analysis that must accompany a State’s assertion that 

CAIR is sufficient for reasonable progress for subject EGU’s during the first planning period. 

From past experience in examining multi-pollutant emissions trading programs for SO2 

and NOX, EPA recognized that the air pollution control retrofits that result from a 

program to achieve highly cost-effective reductions are quite significant and can not be 

immediately installed. Such retrofits require a large pool of specialized labor resources, 

in particular, boilermakers, the availability of which will be a major limiting factor in the 

amount and timing of reductions. 
Regional Haze SIP 87 

for North Carolina Class I Areas December 17, 2007 

Also, EPA recognized that the regulated industry will need to secure large amounts of 

capital to meet the control requirements while managing an already large debt load, and 

is facing other large capital requirements to improve the transmission system. 

Furthermore, allowing pollution control retrofits to be installed over time enables the 

industry to take advantage of planned outages at power plants (unplanned outages can 

lead to lost revenue) and to enable project management to learn from early installations 

how to deal with some of the engineering challenges that will exist, especially for the 

smaller units that often present space limitations. 

Based on these and other considerations, EPA determined in the NPR that the earliest 

reasonable deadline for compliance with the final highly cost-effective control levels for 

reducing emissions was 2015 (taking into consideration the existing bank of title IV SO2 

allowances). First, the Agency confirmed that the levels of SO2 and NOX emissions it 

believed were reasonable to set as annual emissions caps for 2015 lead to highly costeffective controls for the CAIR region. 

Once EPA determined the 2015 emissions reductions levels, the Agency determined a 

proposed first (interim) phase control level that would commence January 1, 2010, the 

earliest the Agency believed initial pollution controls could be fully operational (in 

today's final action, the first NOX control phase commences in 2009 instead of in 2010, 

as explained in detail in section IV.C). The first phase would be the initial step on the 

slope of emissions reductions (the glide-path) leading to the final (second) control phase 

to commence in 2015. The EPA determined the first phase based on the feasibility of 

installing the necessary emission control retrofits, as described in section IV.C. 

Although EPA's primary cost-effectiveness determination is for the 2015 emissions 

reductions levels, the Agency also evaluated the cost effectiveness of the first phase 

control levels to ensure that they were also highly cost effective. Throughout this 

preamble section, EPA reports both the 2015 and 2010 (and 2009 for NOX) costeffectiveness results, although the first phase levels were determined based on feasibility 

rather than cost effectiveness. The 2015 emissions reductions include the 2010 (and 2009 

for NOX) emissions reductions as a subset of the more stringent requirements that EPA is 

imposing in the second phase.

The NCDAQ intends to re-evaluate the IPM predictions of SO2 reductions for CAIR at the time 

of our next periodic report in 2012 to ensure that the reductions are in fact taking place where 

they were predicted. Based on the controls required by CSA, and predicted by IPM under CAIR, 

the NCDAQ has concluded that at this time these existing regulatory programs constitute 

reasonable control measures for North Carolina EGUs during this first assessment period 

(between baseline and 2018). 

Step 4: Determine which emission units would be evaluated based on impact. 

The NCDAQ calculated the fractional contribution from all emission units within the SO2 Area 

of Influence for a given Class I area and identified those emission units with a contribution of 

one percent or more to the visibility impairment at that Class I area. A full description of this 

process and a list of sources considered in the reasonable progress evaluation can be found in 

Appendix H. 
Regional Haze SIP 88 

for North Carolina Class I Areas December 17, 2007 

Step 5: Evaluate the four factors. 

Each emission unit identified in Step 4 above was evaluated using the statutory and regulatory 

factors of 1) cost of compliance, 2) time necessary for compliance, 3) the energy and non-air 

quality environmental impacts of compliance, and 4) the remaining useful life of the emissions 

unit. If any control measure for an emission unit was found reasonable after assessing the four 

factors, modeling would be performed to determine if the controls would result in a visibility 

improvement at any Class I area. 

For the limited purpose of evaluating the cost for the reasonable progress assessment in this first 

regional haze SIP, the NCDAQ believes it is not equitable to require non-EGUs to bear a greater 

economic burden than EGUs for a given control strategy. The NCDAQ used the capital and 

operating costs provide by Duke Energy and Progress Energy for the CSA compliance plans to 

establish a cost/ton of SO2 removed threshold. During the current reasonable progress 

assessment, no units in North Carolina were identified for additional control since no measures 

were found to be below the cost threshold. Below is a summary of the analysis. The detailed 

analysis is included in Appendix H. 

Results of four-factor analysis.

The following is a brief summary of the four-factor analysis. More detail is included in 

Appendix H. The NCDAQ used the cost of compliance as a screening tool to determine the 

universe of sources to perform the full four-factor evaluation. Therefore, the summary is focused 

on the cost of control. The dollar per ton of SO2 removed that the NCDAQ used to determine if 

the cost was reasonable was based on the facility-by-facility and system wide EGU costs for 

implementing CSA and are included as Attachment 2 to Appendix H. The facility-by-facility 

costs ranged from 912 to 1,922 dollars per ton of SO2 removed, and the average costs per system 

ranged from 1,231 to 1,375 dollars per ton of SO2 removed. The CSA controls will reduce SO2 

emissions at North Carolina EGUs by more than 80 percent between 2002 and 2018. 

For non-EGUs, the NCDAQ found that emissions from the following facilities contributed one 

percent or more to visibility impairment in a Class I area, and therefore focused the reasonable 

progress assessments on specific units at these facilities: 

Blue Ridge Paper Products 

PCS Phosphate 

Weyerhaeuser Plymouth 

Weyerhaeuser New Bern 

Congentrix Kenansville 

Additionally, two units at Ecusta Business Development Center contributed more than one 

percent to visibility impairment at Shining Rock Wilderness Area. However, this facility has 

since closed and therefore was not evaluated for reasonable progress. 
Regional Haze SIP 89 

for North Carolina Class I Areas December 17, 2007 

The NCDAQ also looked at what sources in North Carolina may be impacting Class I areas 

located outside of the State, as well as what sources located outside of North Carolina may be 

impacting the North Carolina Class I areas. Letters were sent to the states (see Appendix J) 

identifying which sources in North Carolina may impact their Class I areas and what the 

NCDAQ had deemed as reasonable control measures. Additionally, the letters requested 

information on what each state had deemed as reasonable control measures for their sources 

impacting North Carolina’s Class I areas. The only North Carolina source that was identified, 

outside of facilities listed above, was the Duke Power Dan River facility, which may impact 

James River Face Wilderness in Virginia. Since this facility is subject to CAIR, the NCDAQ 

had deemed no additional controls would be required. 

Blue Ridge Paper Products

Some of the units at Blue Ridge Paper Products were subject to BART. These units were 

analyzed for BART and are addressed in Appendix L. Since the BART a determination takes 

into consideration many of the same factors as for reasonable progress, the BART subject units 

were not re-evaluated in the reasonable progress review. 

The NCDAQ evaluated switching to lower sulfur content coals. Currently, the company is using 

0.75% sulfur coal in one boiler regulated by NSPS. The NCDAQ did cost calculations for the 

following scenario: if 0.75 percent sulfur content coal was required across the mill for the boilers 

that currently use about one percent sulfur coal. This measure could result in 1400 tons SO2 per 

year reduced. 

Based on information from the company, the lower sulfur coal is $75-90 per ton and the other 

coal (one percent sulfur) on site is $65 per ton. The cost is $10-25 per ton difference. The 

company burned 277,214 tons of one percent sulfur coal in 2005; switching to lower sulfur coal 

(0.75%) would cost ~ $2,772,140 - $6,930,350 extra per year. If 1400 tons of SO2 were 

reduced, costs would be in the range of $1980 - $4950 per ton, with an average cost of $3,465 

per ton. 

Add-on control technology for these units cost in the range of $12,055 to $100,961 per ton of 

SO2 removed. The NCDAQ concludes that there are no cost-effective controls available for 

these units at this time within the cost threshold established for this reasonable progress 

assessment. Although the NCDAQ has concluded that for this reasonable progress period there 

are no cost-effective controls, the agency acknowledges that the emissions from Blue Ridge 

Paper Products do have impacts on the Class I areas located in the mountains. The NCDAQ has 

notified the company that although additional controls are not being required this planning 

period, future-planning periods may require controls to be installed. The NCDAQ is committed 

to work with this company over the next review period and to encourage the company to 

modernize some of its processes with more efficient, less polluting equipment. 

PCS Phosphate

Some of the units at PCS Phosphate were subject to BART. These units were analyzed for 

BART and are addressed in Appendix L. Since the BART determination takes into 

consideration many of the same factors as for reasonable progress, the BART subject units were 

not re-evaluated in the reasonable progress review. 
Regional Haze SIP 90 

for North Carolina Class I Areas December 17, 2007 

No control options were listed in the VISTAS’s control cost spreadsheet for any of the four units 

at this facility. The two PCS Phosphate units not subject to BART currently utilize dual 

absorption systems with a vanadium catalyst. Other technologies reviewed included sodium 

bisulfite scrubbing, molecular sieve, ammonia scrubbing, and dual absorption process with 

cesium-promoted catalyst. The first 3 options were rejected because they have not been 

commercially demonstrated to reliably meet current NSPS and state permit limits. The fourth 

was found to cost $3,433/ton to $3,457/ton SO2 reduced based on a reduction of sulfur emissions 

from 3.8 to 3.5 lb SO2/ton sulfuric acid. Therefore, the NCDAQ concludes that there are no 

cost-effective controls available for these units at this time within the cost threshold established 

for this reasonable progress assessment. The NCDAQ has notified the company that although 

additional controls are not being required this planning period, future-planning periods may 

require controls to be installed. 

In addition, PCS Phosphate has submitted a Prevention of Significant Deterioration application 

to the NCDAQ. The company plans to shut down the two sulfuric acid plants subject to BART 

and build one new plant. Preliminary review of the application indicates that the total facility 

SO2 emissions may decrease with these changes. 

Weyerhaeuser Plymouth

Weyerhauser Plymouth contains two boilers burning a combination of fuels. There were no 

controls suggested for the Boiler 1 or 2 in the VISTAS Control Cost Spreadsheet. For the Riley 

Boiler, the control suggested by VISTAS Control Cost Spreadsheet is an FGD at a cost of 

$20,460 per ton of SO2 removed. Therefore, the NCDAQ concludes that there are no costeffective controls available for these units at this time within the cost threshold established for 

this reasonable progress assessment. 

Weyerhaeuser New Bern

Weyerhaeuser New Bern contains one residual oil-fired boiler. The control suggested by 

VISTAS Control Cost Spreadsheet is an FGD at a cost of $17,317 per ton of SO2 removed. 

Therefore, the NCDAQ concludes that there are no cost-effective controls available for these 

units at this time within the cost threshold established for this reasonable progress assessment. 

Cogentrix Kenansville

Congentrix Kenansville is currently burning unadulterated wood (pure wood with up to 5% 

impurities). The company retains coal as a permitted fuel on the permit, with no immediate 

plans to use it. They are currently burning wood and their new business plan is to continue just 

burning wood as part of the "green power" movement here in North Carolina. 

The 2005 actual SO2 emissions for this unit were 23.25 tons, whereas the projected 2018 SO2 

emissions were 1,833.8 tons based on using coal. The NCDAQ is sending the company a letter 

indicating that they are currently on the list of sources contributing greater than one percent 

contribution to visibility impairment at Swanquarter Wildlife Refuge based on the estimated 

emissions from burning coal. The letter will suggest that they change their permit to remove 

coal as a possible fuel source for this unit. 
Regional Haze SIP 91 

for North Carolina Class I Areas December 17, 2007 

Summary:

During the current reasonable progress assessment no units in North Carolina were identified for 

additional control since no measures were found to be below the cost threshold discussed in 

Step 5. In addition to costs, the statutory factors include time necessary for compliance, 

remaining useful life of the facility, and energy and non-air environmental impacts of the control 

installation. However, since no cost effective control measures were identified for the specific 

sources with contributions to North Carolina or neighboring States’ Class I areas, the NCDAQ 

did not invest in an exhaustive review of the remaining three factors beyond that described in 

Section 6.4 for control options for major SO2 source sectors. Neither the time necessary for 

compliance nor the energy and non-air quality environmental impacts of compliance appear to be 

out of the ordinary for any of these facilities. A likely short remaining useful life for two units 

was noted in one case, but a longer remaining useful life would not alter that particular 

determination. 

It should be noted that, in order to show continued progress past 2018, the criteria will likely be 

different in the next reasonable progress assessment in order to maintain a continuous downward 

glidepath toward natural background conditions by 2064. The facilities in North Carolina that 

have units that contribute at least one percent to visibility impairment at any Class I area in the 

State, or in neighboring States, were sent letters from the NCDAQ indicating that while no 

additional controls were identified during this reasonable progress assessment, the sources 

should be evaluating possible SO2 reduction strategies for the next round of regional haze SIP 

development. Those letters are contained in Appendix H.3. 

7.9 What Additional Emissions Controls Were Considered as part of the Long-Term 

Strategy for Visibility Improvement by 2018? 

Section 308(d)(3)(v) of the regional haze rule lists several factors that must be addressed in each 

SIP. These factors include the role of fire at Class I areas and status of state planning for smoke 

management, the role of dust and fine soil at Class I areas and status of state plans to mitigate 

emissions from construction activities, and the role of NH3 and potential benefits if emissions 

from agricultural sources were mitigated. 

As discussed in Section 2.4 and demonstrated in Figures 2.4-1 and 2.4-2, elemental carbon 

(sources include agricultural burning, prescribed wildland fires, and wildfires) is a relatively 

minor contributor to visibility impairment at the Class I areas in North Carolina. However, the 

NCDAQ is currently working with the North Carolina Division of Forest Resources to develop a 

smoke management program that utilizes basic smoke management practices and addresses the 

issues laid out in the USEPA’s 1998 Interim Air Quality Policy on Wildland and Prescribed 

Fires. Additionally, the NCDAQ is working with the North Carolina Department of Agriculture 

to develop a Memorandum of Understanding regarding agricultural burning. The NCDAQ 

anticipates that the resulting smoke management program and Memorandum of Understanding 

should be sufficient to satisfy the directive in 40 CFR 51.308(d)(3)(v)(E). 

Also as discussed in Section 2.4 and demonstrated in Figures 2.4-1 and 2.4-2, fine soils are a 

relatively minor contributor to visibility impairment at the Class I areas in North Carolina. 

Nevertheless, in regard to construction activities, the NCDOT Division of Highways has issued 
Regional Haze SIP 92 

for North Carolina Class I Areas December 17, 2007 

regulations addressing control of erosion, siltation, and pollution from construction activities. 

Section 107-13(E) of the Division of Highways General Contract Specifications, Division 1 

General Requirements, reads as follows: 

(E) Dust Control 

The Contractor shall control dust throughout the life of the project within the project area 

and at all other areas affected by the construction of the project, including, but not 

specifically limited to, unpaved secondary roads, haul roads, access roads, disposal sites, 

borrow and material sources, and production sites. Dust control shall not be considered 

effective where the amount of dust creates a potential or actual unsafe condition, public 

nuisance, or condition endangering the value, utility, or appearance of any property. 

The Contractor will not be directed compensated for any dust control measures 

necessary, as this work will be considered incidental to the work covered by the various 

contract items. 

In addition, the NCDAQ has recently promulgated a new rule, effective on September 1, 2007, 

intended to control particulates from fugitive dust emission sources generated within plant 

boundaries from activities such as “unloading and loading areas, process areas, stockpiles, stock 

pile working, plant parking lots, and plant roads (including access roads and haul roads).” 

Note that benefits from neither the new rule nor the NCDOT dust ordinance have been included 

in the VISTAS modeling runs. Copies of the dust ordinance and the NCDAQ rule are attached 

to Appendix H. 

In regard to agricultural ammonia, the NCDAQ, as a continuation of the CSA, initiated the 

Climate Action Planning Advisory Group (CAPAG) to develop widespread and specific options 

for the reduction of greenhouse gas emissions in North Carolina. The CAPAG is comprised of 

leaders from agricultural, industrial, local and state governmental, and environmental sectors in 

North Carolina. This collaborative effort developed mitigation options through a consensus 

process to simultaneously address the goal of reducing green house gas emissions and improve 

the quality of life in North Carolina. Agriculture and waste in North Carolina is one of the 

major areas being developed to reduce greenhouse gases. Since North Carolina is second in the 

nation in production of pork, one of the options being developed promotes increased use of the 

energy content of hog and cattle waste through the expansion of biodigesters. 

To accomplish the expanded utilization of methane (a greenhouse gas) from hog/cattle waste for 

energy, the report supports expanded research, regulatory actions, and grant guarantees as key 

implementation tools. Inherent to the success are improved waste management practices. With 

increased support and improved management a co-benefit will be the reduction of ammonia 

emissions from animal waste. As less ammonia will be applied to soils, lower direct emissions 

of ammonia will occur and lower emissions of nitrous oxide (N2O), a potent greenhouse gas, 

from soils will occur. The exact benefits from the reduction in ammonia emissions have not 

been quantified. 

In addition, the North Carolina Legislature approved a bill on July 26, 2007 that permanently 

bans new hog lagoons and orders state regulators to set environmental standards for new waste 
Regional Haze SIP 93 

for North Carolina Class I Areas December 17, 2007 

systems. The new legislation creates a phase-out of waste lagoons used by hog farmers, replacing 

them with more environmentally friendly systems paid for in part by taxpayer-funded grants. 

The bill is included as an attachment to Appendix H. 

VISTAS is working on a modeling run that will include the cumulative benefits from the 

emission controls discussed in Section 7.2.1, any controls resulting from BART determinations 

within the other VISTAS states and any controls resulting from the other states within VISTAS 

to address reasonable control measures. These modeling results were not completed in time to 

be included with this Regional Haze SIP. Additionally, not all states within VISTAS have 

completed their reasonable control measures analysis and the modeling does not include controls 

resulting from BART determinations or reasonable control measures from states located outside 

the VISTAS region. Since it may take a significant amount of time to have a modeling run 

completed that incorporates all of these measures, the NCDAQ has decided that it will 

incorporate these types of results in the first periodic review in 2012. 

8.0 REASONABLE PROGRESS GOALS 

The regional haze rule at 40 CFR 51.308(d)(1) requires a State to establish reasonable progress 

goals for each Class I area within the State (expressed in deciviews) that provide for reasonable 

progress towards achieving natural visibility conditions by 2064. In addition, the USEPA 

released guidance on June 7, 2007 to use in setting reasonable progress goals. The goals must 

provide improvement in visibility for the most impaired days, and ensure no degradation in 

visibility for the least impaired days over the SIP period. 

In accordance with the requirements of 40 CFR 51.308(d)(1), this Regional Haze SIP establishes 

the uniform rate of progress for each Class I area in North Carolina. The NCDAQ compared 

baseline visibility conditions to natural visibility conditions in each Class I area to determine the 

uniform rate of visibility improvement (in deciviews) that would need to be maintained during 

each implementation period in order to attain natural visibility conditions by 2064. 

Through the VISTAS modeling, the NCDAQ has estimated the expected visibility improvements 

by 2018 in each Class I area resulting from existing federal and state regulations. As stated 

earlier, VISTAS is in the process of modeling additional control measures found to be reasonable 

to implement in this review period by the other VISTAS states, as well as the results of other 

VISTAS states’ BART determinations. These modeling results were completed in time to be 

included with this Regional Haze SIP. The VISTAS baseline modeling has already 

demonstrated that the 2018 base control scenario provides for an improvement in visibility better 

than the uniform rate of progress for all North Carolina Class I areas for the most impaired days 

over the period of the implementation plan and ensures no degradation in visibility for the least 

impaired days over the same period. 

North Carolina and Tennessee are sharing the lead for the Great Smoky Mountains National Park 

since it is located in both states. The NCDAQ and the Tennessee Division of Air Pollution 

Control have agreed to work together in setting reasonable progress goals and both agencies have 

been working together, through VISTAS, throughout the regional haze SIP planning process. 
Regional Haze SIP 94 

for North Carolina Class I Areas December 17, 2007 

Table 8.0-1 contains the reasonable progress goals for this planning period for each of the North 

Carolina Class I areas. For the 20% worst days, the reasonable progress goal for each area 

provides for greater visibility improvement by 2018 than the area’s uniform rate of progress. For 

the 20% best days, the reasonable progress goal for each area indicates an improvement of 

visibility by 2018 than current best day conditions. These goals are based on the modeling 

results discussed in Section 7.2.4. The model performance for the 20% best days is not as good 

as for the 20% worst days because the model has greater difficulty accurately projecting small 

concentrations. On the 20% best days, the model does not meet VISTAS model performance 

goals or criteria for sulfate, nitrate, and coarse mass (under predicted) and soil (over predicted), 

however, the organic carbon and elemental carbon do meet performance goals on the 20% best 

days. Given the larger percent errors of the fractional bias on the 20% best days, the NCDAQ 

has less confidence in the absolute values projected for these reasonable progress goals, 

however, the NCDAQ does expect that visibility on these days will be better than the current 

conditions 20% best days. 

Table 8.0-1. North Carolina 2018 Reasonable Progress Goals (in deciviews) 

Class I Area 

Baseline Visibility

for 20% 

Worst Days 

Reasonable 

Progress Goal - 

20% Worst Days 

(Improvement) 

Baseline Visibility 

for 20% 

Best Days 

Reasonable 

Progress Goal - 

20% Best Days 

(Improvement) 

Great Smoky 

Mountains National 

Park 

30.3 23.7 

(6.6) 13.6 12.2 (1.4) 

Joyce KilmerSlickrock Wilderness 

Area 

30.3 23.7 

(6.6) 13.6 12.2 (1.4) 

Linville Gorge 

Wilderness Area 28.8 22.0 (6.8) 11.1 9.6 (1.5) 

Shining Rock 

Wilderness Area 28.5 22.1 (6.4) 7.7 6.9 (0.8) 

Swanquarter Wildlife 

Refuge 24.7 20.4 (4.3) 12.0 11.0 (1.0) 

9.0 MONITORING STRATEGY 

The Regional Haze SIP is to be accompanied by a strategy for monitoring regional haze visibility 

impairment. Specifically, the regional haze rule states at 40 CFR 51.308(d)(4): 
Regional Haze SIP 95 

for North Carolina Class I Areas December 17, 2007 

“(4) Monitoring strategy and other implementation plan requirements. The State must 

submit with the implementation plan a monitoring strategy for measuring, characterizing, 

and reporting of regional haze visibility impairment that is representative of all 

mandatory Class I Federal areas within the State. This monitoring strategy must be 

coordinated with the monitoring strategy required in §51.305 for reasonably attributable 

visibility impairment. Compliance with this requirement may be met through 

participation in the IMPROVE network. The implementation plan must also provide for 

the following: 

(i) The establishment of any additional monitoring sites or equipment needed to 

assess whether reasonable progress goals to address regional haze for all 

mandatory Class I Federal areas within the State are being achieved. 

(ii)-(vi) [Other implementation plan requirements that pertain to reporting and use 

of monitoring data and an emission inventory.]” 

Such monitoring is intended to provide the data needed to satisfy four objectives: 

1. Track the expected visibility improvements resulting from emissions reductions 

identified in this SIP. 

2. Better understand the atmospheric processes of importance to haze 

3. Identify chemical species in the ambient particulate matter and relate them to emissions 

from sources 

4. Evaluate regional air quality models for haze and construct relative response factors for 

using those models 

The primary monitoring network for regional haze, both nationwide and in North Carolina, is the 

IMPROVE network. Given that IMPROVE monitoring data from 2000-2004 serves as the 

baseline for the regional haze program, the future regional haze monitoring strategy must 

necessarily be based on, or directly comparable to, IMPROVE. The IMPROVE measurements 

provide the only long-term record available for tracking visibility improvement or degradation 

and therefore North Carolina intends to rely on the IMPROVE network for complying with the 

regional haze monitoring requirement in the Regional Haze Rule. 

There are currently 3 IMPROVE sites in North Carolina (2 at distinctly different locations in the 

mountains and one on the coast). In addition, as Table 9.0-1 shows, an IMPROVE site just 

across the border in Tennessee serves as the monitoring site for both the Great Smoky Mountains 

National Park and Joyce Kilmer-Slickrock Wilderness Area, both of which lie partly in 

Tennessee and partly in North Carolina. 
Regional Haze SIP 96 

for North Carolina Class I Areas December 17, 2007 

Table 9.0-1. North Carolina Class I Areas and Representative IMPROVE Monitor 

Class I Area IMPROVE Site Designation 

Great Smoky Mountains National Park GRSM1 (TN) 

Joyce Kilmer-Slickrock Wilderness Area GRSM1 (TN) 

Linville Gorge Wilderness Area LIGO1 (NC) 

Shining Rock Wilderness Area SHRO1 (NC) 

Swanquarter Wildlife Refuge SWAN1 (NC) 

In addition to the IMPROVE measurements, some ongoing long-term limited monitoring 

supported by Federal Land Managers provides additional insight into progress toward regional 

haze goals. North Carolina benefits from the data from these measurements, but is not 

responsible for the funding decisions to maintain these measurements into the future. Such 

measurements include: 

• Web cameras operated by the National Park Service at Look Rock, Tennessee and 

Purchase Knob, North Carolina in Great Smoky Mountains National Park and by the 

United States Forest Service at Frying Pan Mountain in the Shining Rock Wilderness 

Area. 

• An integrating nephelometer for continuously measuring light scattering, operated by the 

National Park Service at Look Rock, Tennessee. 

• A Tapered Element Oscillating Microbalance (TEOM) for continuously measuring 

PM2.5 mass concentration, operated by the National Park Service at Look Rock, 

Tennessee. 

Additional haze-related measurements were made in North Carolina in 2002-2005 as part of 

special monitoring studies by the VISTAS regional planning organization. These studies were 

intended to better understand source contributions to PM2.5 mass and visibility. They included 

continuous monitoring of sulfate, nitrate, and carbon to better understand daily trends in PM2.5, 

detailed analyses of carbon collected on filters to identify source contributions to carbon, and 

additional analyses of sodium and ammonium on IMPROVE filter samples. Funding does not 

exist to continue these special studies, however, the equipment has been transferred to the 

NCDAQ. 

The continuous nitrate monitor continues to operate at the Millbrook site in Raleigh and the 

NCDAQ intends to operate this monitor as long as funds allow. Additionally, a second 

continuous nitrate monitor is in operation at the Rockwell monitoring site in Rowan County. 

Again, the NCDAQ plans to operate this monitor indefinitely as long as funds allow. The 

NCDAQ began operating a continuous sulfate monitor at the Millbrook in August 2007, and 

expect to have one at the Rockwell sites in January 2008. The NCDAQ is also operating a 5400 

R&P monitor for organic, total, and elemental carbon at the Millbrook site. The 5400 R&P 

monitor is near the end of its lifecycle, but the NCDAQ plans to operate it as long as it can be 

kept functional or until money is available to purchase a better technology should such a 
Regional Haze SIP 97 

for North Carolina Class I Areas December 17, 2007 

technology become available. VISTAS also transferred a 5400 R&P monitor from the Look 

Rock special studies location, but the unit is inoperable. The NCDAQ used it for parts for the 

Millbrook unit, thus, a 5400 R&P unit is not available for the Rockwell site. At this time, the 

NCDAQ does intend to purchase one to place there due to the short lifecycle of the unit and the 

various operating issues. 

In February 2008, the NCDAQ will finish a year-long black carbon study in Hickory with the 

aethalometer that was used at the Millbrook site. Depending on the results of the study, this 

monitor may remain at the Hickory site, return to the Millbrook site, or go to the Rockwell site. 

The NCDAQ will use the continuous speciation data from the sites discussed above to further the 

understanding of both PM2.5 and visibility formation and trends in North Carolina. The 

NCDAQ will operate the units discussed above as long as funds allow. 

In addition, the NCDAQ and the local air agencies in the State operate a fairly comprehensive 

PM2.5 network of the filter based Federal reference method monitors, continuous mass monitors 

(TEOMs), filter based speciated monitors and the continuous speciated monitors described 

above. A map of the various locations around the State is included in Figure 9.0-1. These PM2.5 

measurements help the NCDAQ characterize air pollution levels in areas across the state, and 

therefore aid in the analysis of visibility improvement in and near the Class I areas. 

Figure 9.0-1 PM2.5 Monitoring Network in North Carolina 

The IMPROVE measurements are central to North Carolina’s regional haze monitoring strategy, 

and it is difficult to visualize how the objectives listed above could be met without the 
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for North Carolina Class I Areas December 17, 2007 

monitoring provided by IMPROVE. Any reduction in the scope of the IMPROVE network in 

North Carolina would jeopardize the State’s ability to demonstrate reasonable progress toward 

visibility improvement in some of its Class I areas. In particular, North Carolina’s regional haze 

strategy relies on emission reductions that will result from the CAIR and the CSA, which occur 

on different time scales and will most likely not be spatially uniform. Monitoring at every Class I 

area is important to document the different air quality responses to the emissions reductions. 

Because each of the current IMPROVE monitors in North Carolina represents a different airshed, 

reduction of the IMPROVE network by shutting down one of these monitoring sites impedes 

tracking progress at reducing haze at the affected Class I area. In the event this occurs, North 

Carolina, in consultation with the USEPA and relevant Federal Land Managers, will develop an 

alternative approach for meeting the tracking goal, perhaps by seeking contingency funding to 

carry out limited monitoring or by relying on data from nearby urban monitoring sites to 

demonstrate trends in speciated PM2.5 mass. 

Data produced by the IMPROVE monitoring network will be used nearly continuously for 

preparing the 5-year progress reports and the 10-year SIP revisions, each of which relies on 

analysis of the preceding five years of data. Consequently, the monitoring data from the 

IMPROVE sites needs to be readily accessible and to be kept up to date. Presumably, IMPROVE 

will continue to process information from its own measurements at about the same pace and with 

the same attention to quality as it has shown in the recent past. The VIEWS web site has been 

maintained by VISTAS and the other Regional Planning Organizations to provide ready access 

to the IMPROVE data and data analysis tools. North Carolina is encouraging VISTAS and the 

other RPOs to maintain VIEWS or a similar data management system to facilitate analysis of the 

IMPROVE data. 

10.0 CONSULTATION PROCESS 

The VISTAS states have jointly developed the technical analyses to define the visibility 

improvement by 2018 under existing federal and state regulations compared to the uniform rate 

of progress, SO2 Areas of Influence for each Class I area, and methods to prioritize contributions 

from individual sources within the Areas of Influence. The states collectively accept the 

conclusions of these analyses. 

In December 2006, the VISTAS State Air Directors held their first formal consultation meeting 

to review the modeling results and the SO2 Areas of Influence analyses. The Air Directors 

agreed to look at reasonable control measures for sources on the lists for the SO2 Areas of 

Influence. Each state would consider sources within their state and would identify sources in 

neighboring states that they would like to have that neighboring state consider. States 

acknowledged that the review process would differ among states since some Class I areas are 

projected to see visibility improvements near the uniform rate of progress while most Class I 

areas are projected to have greater improvements than uniform rate of progress. 

In May 2007, the VISTAS State Air Directors met for their second formal interstate consultation. 

States shared their lists of sources in their state and neighboring states for each Class I area. 
Regional Haze SIP 99 

for North Carolina Class I Areas December 17, 2007 

They also shared their criteria for listing sources and their plans for further interstate 

consultation. A summary of this meeting is included in Appendix J. 

The NCDAQ has evaluated the impact of North Carolina sources on Class I areas in neighboring 

states and determined that there are no additional reasonable control measures that should be 

implemented to mitigate impacts in Class I areas in neighboring states. The NCDAQ has 

consulted with the responsible states regarding its evaluation showing no cost-effective controls 

available for those units contributing at least one percent to visibility impairment at Class I areas. 

Analyses of impacts from North Carolina sources and potential controls are discussed in greater 

detail in Appendix H. Copies of the consultation letters may be found in Appendix J. 

Additionally, the NCDAQ sent letters to states where sources outside of North Carolina were 

determined to contribute one percent or higher to a North Carolina Class I area. Four states have 

responded to the consultation letters that were sent out: Delaware, Georgia, South Carolina and 

Virginia. Delaware sent information about their multi-pollutant rule and the expected emissions 

for the identified source. With the new emissions included in the analysis, the Delaware source 

no longer contributed one percent or greater to Swanquarter Wilderness Area. Georgia has 

determined that CAIR is sufficient for the EGUs and summarized their expected controls due to 

their recently passed rule controlling EGUs. Georgia also identified another source that 

contributes 0.5 percent to the Joyce Kilmer-Slickrock Wilderness Area and is in the process of 

reviewing a four factor analysis received from this facility. South Carolina has also determined 

that CAIR is sufficient for EGUs and no additional controls are required. Virginia provided their 

reasonable progress analysis for the facility identified to impact Swanquarter Wildlife Refuge. 

Their analysis showed that the source is currently controlled and that no additional reasonable 

controls were available for the identified source. Copies of the consultation letters may be found 

in Appendix J. 

The MANE-VU states of Maine, New Jersey, New Hampshire, and Vermont sent letters to North 

Carolina in the spring of 2007 stating that based on 2002 emissions, North Carolina contributed 

to visibility impairment to Class I areas in those states. MANE-VU states asked the NCDAQ to 

participate in further consultation with these states, and a meeting was held in August 2007, in 

Atlanta, Georgia. 

The MANE-VU states identified 12 EGUs in North Carolina that they would like to see 

controlled to 90% efficiency. They also requested a control strategy to provide a 28% reduction 

in SO2 emissions from sources other than EGUs that would be equivalent to their low sulfur fuel 

oil strategy. North Carolina has controlled or is expecting to control under CSA 11 of the 12 

identified EGUs. Additionally, scrubbers are expected on three EGUs that were not identified by 

MANE-VU. The NCDAQ believes that these reductions satisfy MANE-VU’s request. The 

letters from these states, the responses from the NCDAQ, and the meeting notes are included in 

Appendix J. 

In September 2007, the NCDAQ had consultation meetings with the FLMs regarding the initial 

pre-hearing draft Regional Haze SIP shared with them in August 2007. In these meetings the 

FLMs provided feedback to the NCDAQ of changes or clarifications they would like to see in 

the SIP. All three FLMs (FS, NPS and FWS) expressed their concerns about Blue Ridge Paper 
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for North Carolina Class I Areas December 17, 2007 

Products located in Canton, North Carolina and its impacts on the mountain Class I areas. The 

NPS and FWS also expressed concern about PCS Phosphate, located in Aurora, North Carolina 

and its impacts on Swanquarter Wildlife Refuge. The NCDAQ explained the process it went 

through to determine reasonable, cost-effective control measures and stated that the NCDAQ has 

notified the company that although additional controls are not being required this planning 

period, future planning periods may require controls to be installed. The NCDAQ intends to 

have discussions with Blue Ridge Paper Products over the next review period and to encourage 

the company to modernize some of its processes with more efficient, less polluting equipment. 

On October 2, 2007, and October 9, 2007, the NCDAQ received official comment letters from 

the U. S. Department of Interior and the USFS, respectively, on the pre-draft version of the 

Regional Haze SIP. Copies of these comments, as well as the NCDAQ’s response to comments 

are included in Appendix J, satisfying the requirements of 51.308(i)(3) of the regional haze rule. 

11.0 COMPREHENSIVE PERIODIC IMPLEMENTATION PLAN 

REVISIONS 

40 CFR 51.308(f) requires the NCDAQ to revise its regional haze implementation plan and 

submit a plan revision to the USEPA by July 31, 2018 and every ten years thereafter. In 

accordance with the requirements listed in Section 51.308(f) of the federal rule for regional haze, 

North Carolina commits to revising and submitting this regional haze implementation plan by 

July 31, 2018 and every ten years thereafter. 

In addition, 51.308(g) requires periodic reports evaluating progress towards the reasonable 

progress goals established for each mandatory Class I area. In accordance with the requirements 

listed in 51.308(g) of the federal rule for regional haze, the NCDAQ commits to submitting a 

report on reasonable progress to the USEPA every five years following the initial submittal of 

the SIP. The report will be in the form of a SIP revision. The reasonable progress report will 

evaluate the progress made towards the reasonable progress goal for each mandatory Class I area 

located within North Carolina and in each mandatory Class I area located outside North Carolina 

which may be affected by emissions from within North Carolina. 

The requirements listed in 51.308(g) include the following: 

1. Description of the status of implementation; 

2. Summary of emission reductions achieved thus far, including especially the status of 

implementation of the CAIR compliance plans for EGUs compared to the control 

assumed in the modeling. 

3. Assessment of changes in visibility conditions at each Class I area (current vs. baseline), 

expressed as 5-year averages of annual values for 20% best and worst days; 

4. Analysis of emission changes over the 5-year period, identified by source or activity, 

5. Analysis of any significant changes in or out of the State which have impeded progress; 

6. Assessment of the sufficiency of the implementation plan to meet Reasonable progress 

goals; 

7. Review and any modifications to our visibility monitoring plan. 
Regional Haze SIP 101 

for North Carolina Class I Areas December 17, 2007 

All requirements listed in 51.308(g) shall be addressed in the SIP revision for reasonable 

progress. In particular, the NCDAQ recognizes that the 2018 projections of EGU controls from 

the IPM runs represent one solution to how the CAIR requirements will be met. By the time of 

the first periodic report, the NCDAQ anticipates that the actual compliance strategy for the 

various utility companies will be much more defined. An assessment of those actual compliance 

plans will be done for the first periodic report. 

The NCDAQ believes that its New Source Review regulations for both nonattainment areas as 

well as the prevention of significant deterioration will address emissions from new sources that 

may located near a Class I area, or increased emissions from major modifications to existing 

sources. In addition to the NCDAQ regulations that would govern these sources, consultation 

with the FLMs is also required for sources that are subject to the new source review regulations. 

The NCDAQ also commits to ongoing consultation with the FLMs throughout the 

implementation process, including annual discussion of the implementation process and the most 

recent IMPROVE monitoring data and VIEWS data. 

There are several technical improvements that are recommended in the emissions inventory and 

air quality models that are used to support regulatory decisions for regional haze. These 

recommended improvements, as funding is available, can support the next long term strategy. 

The following is an overall summary; Appendix K contains a more detailed discussion of 

possible technical improvements. 

First and foremost, continued improvements are needed in the integrated one-atmosphere air 

quality models that are used to project air quality responses to emissions reductions. As our 

understanding of partitioning between gaseous and aerosol phases improves, this understanding 

needs to be reflected in the models. Improvements can also be made in how the models handle 

individual pollutants. Sulfate performance for the CMAQ regional air quality model is good 

overall. However sulfate deposition is frequently overestimated in the models, particularly in the 

summer months. At the coastal sites, when winds are blowing from the Gulf of Mexico or 

Atlantic Ocean, CMAQ underestimates measured sulfate at the monitors. CMAQ’s processes 

also should be reviewed for sulfate formation over water. Nitrate is overestimated by the model 

in the winter and underestimated in the summer, although summer monitored values of nitrate 

are very low. Additional improvements in seasonal allocation of ammonia emissions would 

improve model estimates of ammonium nitrate formation. Organic carbon is generally 

underestimated in the summer months. Improvements are needed in the characterization of both 

primary carbon emissions and formation of secondary organic carbon. 

Other improvements needed include better tools for organic carbon source apportionment, and 

more consistent measurement techniques between rural and urban monitoring networks. To 

improve our understanding of the contribution of fire from natural forest fires, prescribed 

burning, land clearing, and agricultural burning, states need improved record keeping. 

Additional improvements to international emissions inventory are also needed to improve our 

understanding of boundary conditions for our modeling domain and of the contributions from 

international emissions to pollutant concentrations at the VISTAS Class I areas. 
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for North Carolina Class I Areas December 17, 2007 

12.0 DETERMINATION OF ADEQUACY OF THE EXISTING PLAN 

Depending on the findings of the five-year progress report, North Carolina commits to taking 

one of the actions listed in 40 CFR 51.308(h). The findings of the five-year progress report will 

determine which action is appropriate and necessary. 

List of Possible Actions – adapted from 40 CFR 51.308(h) 

1) The NCDAQ determines that the existing SIP requires no further substantive revision in 

order to achieve established goals. The NCDAQ provides to the Administrator a negative 

declaration that further revision of the SIP is not needed at this time. 

2) The NCDAQ determines that the existing SIP may be inadequate to ensure reasonable 

progress due to emissions from other states, which participated in the regional planning 

process. The NCDAQ provides notification to the Administrator and the states that 

participated in regional planning. The NCDAQ collaborates with states and FLMs 

through the regional planning process to address the SIP’s deficiencies. 

3) The NCDAQ determines that the current SIP may be inadequate to ensure reasonable 

progress due to emissions from another country. The NCDAQ provides notification, 

along with available information, to the Administrator. 

4) The NCDAQ determines that the existing SIP is inadequate to ensure reasonable progress 

due to emissions within the state. The NCDAQ will consult with FLMs and revise its 

SIP to address the plan’s deficiencies within one year.