Charlotte/Gastonia/Salisbury, NC 2008 8-Hour Ozone Area

Effective July 20, 2012, the U. S. Environmental Protection Agency (EPA) designated the Charlotte-Gastonia-Salisbury, North Carolina nonattainment area (referred to as the Charlotte area) as “marginal” nonattainment for the 2008 8-hour ozone National Ambient Air Quality Standard (NAAQS) based on certified monitoring data from 2009-2011.The nonattainment area included all of Mecklenburg County and portions of Cabarrus, Gaston, Iredell, Lincoln, Rowan, and Union Counties. 

At that time, the design value for the Charlotte area was 0.079 parts per million (ppm) or just 0.004 ppm above the standard of 0.075 ppm. Subsequently, the Charlotte area attained the NAAQS and on April 16, 2015, the North Carolina Division of Air Quality (DAQ) submitted to EPA a request to redesignate the area from marginal nonattainment to attainment which was approved by EPA on July 28, 2015 (effective August 27, 2015). 

The EPA requires that maintenance plans cover the 20-year period after an area is redesignated from nonattainment to attainment to fulfill the requirements of Section 175A(b) of the federal Clean Air Act, as amended. 

DEQ Submittals & EPA Actions

Tab/Accordion Items

On February 28, 2025, the Division of Air Quality (DAQ) submitted the final “Second Ten-Year Maintenance Plan for The Charlotte-Gastonia-Salisbury, North Carolina Maintenance Area for the 2008 8-Hour Ozone National Ambient Air Quality Standard (NAAQS)” to the U.S. Environmental Protection Agency (EPA) for approval into North Carolina's Clean Air Act Section 110 State Implementation Plan (SIP).  This maintenance plan covers the last ten years of the 20-year maintenance period (from August 27, 2025, to August 27, 2035) for the Charlotte-Gastonia-Salisbury, North Carolina maintenance area.  The DAQ prepared the maintenance plan to fulfill the requirements of Clean Air Act (CAA) Section 175A(b) with respect to the second maintenance plan period.  Based on the information provided in this maintenance plan and criteria established in Section 107(d)(3)(E) of the Clean Air Act (CAA), North Carolina requests that EPA approve this maintenance plan for the Charlotte-Gastonia-Salisbury maintenance area.

DEQ Submittals

Please direct any further questions or comments concerning this SIP submittal to the Planning Section Chief.

On December 19, the Division of Air Quality (DAQ) submitted the final “Supplement III to the Revised Maintenance Plan for the Charlotte-Gastonia-Salisbury, North Carolina 2008 8-Hour Ozone Marginal Nonattainment Area” to the U.S. Environmental Protection Agency (EPA) for approval into North Carolina's Clean Air Act Section 110 State Implementation Plan (SIP).  The U.S. Environmental Protection Agency designated the area in attainment of the 2008 8-hour ozone National Ambient Air Quality Standards (NAAQS) effective August 27, 2015 (80 FR 44873).  In this submittal, North Carolina is proposing to increase the amount of the total safety margin allocated to the 2026 motor vehicle emission budgets (MVEBs) from 9.4% to 21.4% for nitrogen oxides (NOx) and from 37.4% to 49.7% for volatile organic compounds (VOC).  The proposed revisions to the 2026 MVEBs will accommodate updates to the MOtor Vehicle Emissions Simulation (MOVES) model (released January 2021) used to calculate onroad emissions of NOx  and VOCs in the Charlotte area;  In addition, the Charlotte-Gastonia-Salisbury area is currently attaining the 2008 and 2015 8-hour ozone NAAQS based on ambient monitoring data collected through October 31, 2022.  Therefore, the DAQ concludes that the proposed revisions to the MVEBs will not interfere with any applicable requirement concerning the attainment and maintenance of the NAAQS.

DEQ Submittals

Please direct any further questions or comments concerning this SIP submittal to the Planning Section Chief.

EPA Actions

On December 19, the Division of Air Quality (DAQ) submitted the final “Supplement III to the Revised Maintenance Plan for the Charlotte-Gastonia-Salisbury, North Carolina 2008 8-Hour Ozone Marginal Nonattainment Area” to the U.S. Environmental Protection Agency (EPA) for approval into North Carolina's Clean Air Act Section 110 State Implementation Plan (SIP).  The U.S. Environmental Protection Agency designated the area in attainment of the 2008 8-hour ozone National Ambient Air Quality Standards (NAAQS) effective August 27, 2015 (80 FR 44873).  In this submittal, North Carolina is proposing to increase the amount of the total safety margin allocated to the 2026 motor vehicle emission budgets (MVEBs) from 9.4% to 21.4% for nitrogen oxides (NOx) and from 37.4% to 49.7% for volatile organic compounds (VOC).  The proposed revisions to the 2026 MVEBs will accommodate updates to the MOtor Vehicle Emissions Simulation (MOVES) model (released January 2021) used to calculate onroad emissions of NOx  and VOCs in the Charlotte area;  In addition, the Charlotte-Gastonia-Salisbury area is currently attaining the 2008 and 2015 8-hour ozone NAAQS based on ambient monitoring data collected through October 31, 2022.  Therefore, the DAQ concludes that the proposed revisions to the MVEBs will not interfere with any applicable requirement concerning the attainment and maintenance of the NAAQS.

DEQ Submittals

Please direct any further questions or comments concerning this SIP submittal to the Planning Section Chief.

EPA Actions

On July 25, 2018, the Department of Environmental Quality (DEQ) submitted a final package to the U.S. Environmental Protection Agency (EPA) to revise North Carolina’s motor vehicle Inspection and Maintenance (I&M) program SIP and Motor Vehicle Emission Control Standard air quality rules to comply with Section 3.5.(b) of Session Law 2017-10 which amended North Carolina General Statute §20-183.2(b) to change the vehicle model year coverage to a rolling 20-year cycle based on the most current year.  This action affected the counties covered by the Maintenance Plan for the Charlotte-Gastonia-Salisbury, North Carolina 2008 8-Hour Ozone Marginal Nonattainment Area.  Revisions to the maintenance plan, Clean Air Act Section 110(l) noninterference demonstration, revisions to North Carolina’s Inspection and Maintenance (I&M) Program SIP, and EPA’s approval of these items are located the I&M Program SIP webpage.

The final "Redesignation Demonstration and Maintenance Plan for the Charlotte-Gastonia-Salisbury, North Carolina 2008 8-Hour Ozone Marginal Nonattainment Area" and the final "Clean Air Act Section 110(l) Non-Interference Demonstration to Support the Gasoline Reid Vapor Pressure (RVP) Standard Relaxation in Gaston and Mecklenburg Counties" were submitted to the U.S. Environmental Protection Agency on April 16, 2015. The narratives for both submittals document that the Charlotte-Gastonia-Salisbury area has attained the 2008 8-hour ozone national ambient air quality standard, fulfilling requirement of Section 175A(b) of the federal Clean Air Act as amended. The transmittal letter, narratives and appendices are available through the following links:

DEQ Submittals

EPA Actions

Redesignation Demonstration and Maintenance Plan

  • Final Rule: Approval and Promulgation of Implementation Plans and Designation of Areas; North Carolina; Redesignation of the Charlotte-Rock Hill, 2008 8-Hour Ozone Nonattainment Area to Attainment (80 FR 44873, July 28, 2015)
  • Proposed Rule: Approval and Promulgation of Implementation Plans and Designation of Areas; North Carolina; Redesignation of the Charlotte Rock Hill, 2008 8-Hour Ozone Nonattainment Area to Attainment (80 FR 29250, May 21, 2015)

Gasoline Reid Vapor Pressure (RVP) Standard Relaxation – Revision to Code of Federal Regulations

  • Direct Final Rule: Approval of North Carolina’s Request to Relax the Federal Reid Vapor Pressure Gasoline Volatility Standard for Mecklenburg and Gaston Counties (80 FR 49164, August 17, 2015)
  • Proposed Rule: Relaxation of the Federal Reid Vapor Pressure Gasoline Volatility Standard for Mecklenburg and Gaston Counties, North Carolina (80 FR 49193, August 17, 2015)

Gasoline RVP Standard Relaxation – Non-Interference Demonstration

  • Final Rule: Approval and Promulgation of Implementation Plans; North Carolina: Non-Interference Demonstration for Federal Low-Reid Vapor Pressure Requirement for Gaston and Mecklenburg Counties (80 FR 44868, July 28, 2015)
  • Proposed Rule: Approval and Promulgation of Implementation Plans; North Carolina: Non-Interference Demonstration for Federal Low-Reid Vapor Pressure Requirement for Gaston and Mecklenburg Counties (80 FR 29230, May 21, 2015)

Please direct any further questions or comments concerning this SIP submittal to the Planning Section Chief.

The final "Charlotte-Gastonia-Salisbury 2008 8-hour Ozone Marginal Nonattainment Area Emissions Inventory and Emissions Statements State Implementation Plan" is available through the following links:

DEQ Submittals

The purpose of the State Implementation Plan is to fulfill the requirements of sections 182(a)(1) and 182(a)(3)(B) of the Clean Air Act, which requires the State of North Carolina to submit a base year (2011) emissions inventory for nitrogen oxides (NOx) and volatile organic compounds (VOCs) in this nonattainment area and to ensure adequate provisions are in place that require the owner or operator of each stationary source of NOx and VOC to provide the state with a statement showing actual emissions within 24 months of designation.

EPA Actions

  • Direct Final Rule: Approval and Promulgation of Implementation Plans; North Carolina; Charlotte; Base Year Emissions Inventory and Emissions Statement for the 2008 8-Hour Ozone Standard (80 FR 22107, April 21, 2015)
  • Proposed rule: Approval and Promulgation of Implementation Plans; North Carolina; Charlotte; Base Year Emissions Inventory and Emissions Statement Requirements for the 2008 8-Hour Ozone Standard (80 FR 22147; April 21, 2015)

Please direct any further questions or comments concerning this SIP submittal to the Planning Section Chief.

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