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Air Quality

Air Pollutants - Ozone - Standards & Requirements

Nonattainment Boundaries and Designations

The federal Clean Air Act requires the U.S. Environmental Protection Agency (EPA) to identify areas in each state using these three designations:

  • Attainment - area meets a National Ambient Air Quality Standard (standard)
  • Nonattainment - area does not meet (or is contributing to nearby areas in not meeting) a standard
  • Unclassifiable - there is not enough data to designate the area under a new or revised standard

EPA sets boundaries for areas designated nonattainment and unclassifiable based on recommendations from the states. States use ambient air monitoring networks, emissions inventories, EPA guidance, and other relevant information to make these recommendations. Furthermore, states and EPA request public input during the process.

See EPA's website for a list or maps of nonattainment areas, and an overview of the designation process.

2008 Ozone
1997 & Previous
Ozone Nonattainment Boundaries

2008 8-Hour Ozone Boundaries

May 21, 2012 EPA published (77 FR 30160) the implementation rule for the 2008 ozone standard, which included the area classifications approach, attainment deadlines and revocation of the 1997 ozone standard for transportation conformity purposes. The effective date of this rule is July 20, 2012.
April 30, 2012 EPA has designated all of South Carolina as unclassifiable/attainment for the 2008 ozone standard, except for a portion of York County. Although the monitor in York County is meeting this standard, EPA included the eastern, urbanized area of York County in the Charlotte-Rock Hill, NC-SC nonattainment area because of its proximity to Charlotte.

This is the same portion of York County that EPA designated as nonattainment for the 1997 ozone standard, with the exception of the Catawba Indian Nation Reservation. EPA included the Catawba Indian Nation Reservation in the 1997 nonattainment area, but the EPA designated it as unclassifiable/attainment for the 2008 ozone standard. For more information, see EPA's website.
February 29, 2012 DHEC responded to EPA's December 8, 2011, proposed boundary for the 2008 ozone standard.
February 7, 2012 EPA proposed the implementation rule for the 2008 ozone standard.
December 20, 2011 EPA announced a public comment period for its responses to states' and tribes' boundary recommendations for the 2008 ozone standard. On January 12, 2012, EPA extended the comment period deadline from January 19, 2012, to February 3, 2012.
December 9, 2011 DHEC certified the ozone monitoring data for the 2011 Ozone Season, further substantiating the "attainment" recommendation for each county of the entire State of South Carolina for the 2008 ozone standard.
December 8, 2011 EPA responded to DHEC's October 11, 2011, boundary recommendation for the 2008 ozone standard. EPA intends to modify DHEC's recommendation so that a portion of York County would be a part of the Charlotte-Gastonia-Salisbury, NC-SC nonattainment area. This is the same portion of York County that EPA designated nonattainment for the 1997 ozone standard. For more information, see EPA's website.
October 11, 2011 DHEC submitted an amendment to the 2008 boundary recommendations to EPA recommending all counties of the entire State be designated attainment.
September 22, 2011 EPA announced that it will implement the 2008 ozone standard. In this announcement, EPA discussed the designation process for the 2008 standard.
January 19, 2010 EPA announced that it was extending by 1 year the deadline for promulgating designations for the 2008 ozone standard that were promulgated in March 2008. The new deadline was set for March 2011.
September 16, 2009 EPA announced it would reconsider the 2008 ozone standard.
July 12, 2009 DHEC submitted an errata to the 2008 boundary recommendations to EPA.
March 12, 2009 Upon delegation of Governor Mark Sanford's authority, DHEC submitted South Carolina's boundary recommendations for the 2008 ozone standard to EPA.

DHEC is prepared to meet new challenges and work closely with EPA and local multi-pollutant Clean Air Coalitions, stakeholders, local and county governments, and our citizens to improve our air quality. During the initial boundary designation process in 2008, DHEC held several meetings around the state announcing the proposed 2008 ozone boundaries, identifying areas with elevated monitored ozone concentrations, and discussing concerns. As a result, DHEC received comments from interested parties on its proposed boundary recommendations.

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1997 8-Hour Ozone Standard Nonattainment Boundary Designations

In 1997, EPA promulgated an 8-hour ozone standard to replace the 1-hour standard. EPA revised the standards to establish the more stringent 8-hour standard at a level of 0.08 ppm. This was done to reflect the latest understanding of the effects of ozone exposure and to provide public health protection with an adequate margin of safety.

1997 8-hour Ozone Early Action Compact (EAC) process

On July 14, 2000, in accordance with the requirements of Section 107 of the Clean Air Act, DHEC submitted initial boundary recommendations for the 1997 8-hour ozone standard. These were based upon 1997 through 1999 monitored ozone data. DHEC recommended that the boundaries of seven Metropolitan Planning Organizations (MPOs) be designated nonattainment areas. EPA then proposed changes, recommending that whole counties be designated nonattainment, and requested more information and further documentation to adequately support the state's partial county recommendations.

On July 14, 2003, the state submitted a revised proposal to EPA for nonattainment area designations. In April 2004, EPA designated three areas in South Carolina as nonattainment but deferred the effective date for two of these areas because of their participation in the Early Action Compact process.

In April 2008, EPA redesignated these areas to attainment.

Rock Hill-Fort Mill Area Transportation Study (RFATS)

On April 30, 2004, EPA issued designations for the 1997 8-hour ozone standard. Although the monitor in York County, South Carolina was meeting the standard, EPA decided the portion of York County within the RFATS Metropolitan Planning Organization (MPO) should be part of the Charlotte-Gastonia-Rock Hill, North Carolina-South Carolina (Metrolina) nonattainment area due to its proximity to Charlotte. On June 8, 2007, EPA classified this area under Title I, Part D, Subpart 2 of the Clean Air Act as a "moderate" nonattainment area for ozone.

On November 15, 2011, EPA issued a "clean data determination" for the Metrolina area in response to the Department's attainment demonstration which was submitted on April 29, 2010.*

On December 26, 2012, EPA published a final approval (77 FR 75862) of the Redesignation Demonstration and Maintenance Plan for the South Carolina portion of the Metrolina nonattainment area which was submitted to EPA on June 1, 2011. This action redesignated the area from nonattainment to attainment and approved South Carolina's 1997 8-hour ozone NAAQS 10-year maintenance plan.

The Department is required to submit a subsequent maintenance plan by December 26, 2020.

*DHEC withdrew the attainment demonstration for the Metrolina nonattainment on January 12, 2012, at EPA's request. The reasonable further progress plans and emissions inventories were not withdrawn.

Previous Ozone Standard Nonattainment Boundary Designations

Cherokee County Boundary Designation

On November 6, 1991, Cherokee County was designated by the EPA as a marginal nonattainment area because of multiple exceedances in 1988 of the 1-hour ozone standard at the air quality monitor located in the Cowpens National Battlefield.

On December 15, 1992, after three consecutive years of satisfactory air quality data, Cherokee County was redesignated by the EPA as attainment for the 1-hour ozone standard.

Additional Resources

Charlotte-Gastonia-Salisbury (SC Portion) Columbia-Newberry Greenville-Spartanburg-Anderson Augusta-Richmond County (SC Portion) Abbeville County

For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.