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Air Quality

Air Pollutants - Ozone - Standards & Requirements

National Ambient Air Quality Standards for Ozone

Since the first ozone National Ambient Air Quality Standard (standard) was established in 1971, EPA has revised them several times. Using the tabs and links below you can find information on the current ozone standard and regulatory actions, as well as a detailed history of ozone standards.

2008 National Ambient Air Quality Standard for Ozone (March 12, 2008)
(Primary and Secondary Standards are the same)

Averaging Time Level (Parts per Million)
8 - Hour 1 0.075

1 To meet this standard, the 3-year average of the fourth-highest daily maximum 8-hour average ozone levels measured at each monitor within an area each year cannot exceed 0.075 ppm.

History and Implementation of the 2008 8-hour standard for Ozone

June 6, 2013 EPA published (78 FR 34178) the proposed 2008 Ozone standard Phase II Implementation Rule. The proposal includes requirements pertaining to attainment demonstrations, reasonable further progress, reasonably available control technology, reasonably available control measures, new source review for nonattainment areas, emission inventories, and SIP submission timelines. The proposal also addresses the revocation of the 1997 ozone NAAQS and anti-backsliding requirements. EPA extended the comment deadline to September 4, 2013 (78 FR 44485).
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 announced release of the final rule directing key aspects of the implementation of the 2008 ozone standard.
February 7, 2012 EPA proposed the implementation rule for the 2008 ozone standard.
September 22, 2011 EPA announced that it would implement the 2008 ozone standard.
September 2, 2011 The White House released a statement asking the EPA to withdraw the reconsidered 2008 ozone standard.
The EPA has released the draft reconsideration rule that it withdrew at the request of the White House.
July 29, 2011 After delaying release of the reconsidered 2008 ozone standard in August, October, and December 2010, EPA again delays announcement of the reconsidered 2008 ozone standard.
March 18, 2010 DHEC submitted its comments on the proposed revisions to the 2008 standard for ozone to EPA.
January 19, 2010 EPA published a proposed revision to the 2008 ozone standard. EPA accepted public comments on these proposed revisions to the ozone standard through March 22, 2010.
September 16, 2009 The EPA announced it would reconsider the 2008 ozone standard.

On March 12, 2009, the South Carolina Department of Health and Environmental Control (DHEC), on behalf of Governor Mark Sanford, submitted South Carolina's boundary recommendations for the 2008 Ozone National Ambient Air Quality Standard. On September 16, 2009, the U.S. Environmental Protection Agency (EPA) announced it would reconsider the 2008 standard for ozone. EPA will propose any needed revisions to the ozone standards by December 2009 and issue a final decision by August 2010.

As a result of EPA's reconsideration announcement, DHEC will not continue efforts on the boundary recommendations for the 2008 ozone standard as EPA will not designate areas in March 2010 for that standard. However, DHEC's goal is to stay ahead of the standards so we will continue efforts to reduce emissions that contribute to ozone pollution.

DHEC has worked with local multi-pollutant Clean Air Coalitions for the past several years on efforts to meet national air quality standards sooner than required. These coalitions continue to pursue actions that improve air quality in general - focusing on multi-pollutant efforts that reduce emissions that contribute to ozone and particulate matter, and that also reduce air toxics and greenhouse gas emissions. Local stakeholders are more engaged than ever in air quality issues and understanding how the decisions made locally impact air quality.

DHEC believes that the continuing success of these local air quality coalitions is key to the State improving air quality and will be critical to meeting EPA's "new" ozone standard. These local, sustained efforts offer the best opportunity to get things done in the most efficient way possible especially with the various and unique air quality challenges facing our State. Any local emission reductions that can reduce ozone levels in 2010 may be the difference between nonattainment and attainment for many areas. Reductions can also make a difference to the "classification" EPA assigns a nonattainment area (ie: the closer an area is to meeting the standard, the fewer federal mandates an area is required to meet).

DHEC continues to work both with EPA and with these local coalitions to implement the best course of actions to bring cleaner air sooner to the South Carolina. Current examples being implemented or under consideration by local areas include: strengthening county open burning ordinances, reducing unnecessary idling for both school buses and fleet vehicles, reducing diesel emissions through the Diesel Emissions Reduction Act, developing efficient energy plans for existing buildings, pursuing park and ride sites to encourage carpooling and developing plans to reduce traffic congestion and stimulating the economy through more efficient commuter options to provide better access to jobs.

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March 27, 2008 EPA published the 2008 ozone standard.

Additional Resources


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