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Ground-level Ozone Pollution

Redesignation and Clean Data Policy (CDP)

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Redesignation Guidance 

Procedures for Processing Requests to Redesignate Areas to Attainment: one principal source of EPA guidance on redesignations to attainment can be found in this memorandum from John Calcagni, Director, Air Quality Management Division, September 4, 1992.

The main requirements of redesignation are:
  • a state must meet the applicable requirements of section 110 and Part D that become due prior to the state's submittal of a complete redesignation request to EPA;
  • the EPA will not need to consider the required SIP elements that became due after submittal of the redesignation request; 
  • planning requirements remain due until EPA completes final action approving a redesignation request.

Main Requirements of the Clean Data Policy

In designated nonattainment areas where monitored data demonstrate that the National Ambient Air Quality Standards (NAAQS) have been achieved, EPA interprets certain requirements of the Clean Air Act as no longer applicable for so long as air quality continues to meet the standard. This interpretation of the Clean Air Act is known as the Clean Data Policy (CDP).

  • Under the Clean Data Policy, EPA may issue a determination of attainment (known informally as a Clean Data Determination) after notice and comment rulemaking determining that a specific area is attaining the relevant standard. 
  • For such areas the requirement to submit to EPA those SIP elements related to attaining the NAAQS is suspended for so long as the area continues to attain the standard. 
  • These planning elements that are suspended include:
    • reasonable further progress (RFP) requirements;
    • attainment demonstrations;
    • Reasonably Available Control Measures (RACM);
    • contingency measures; and
    • other state planning requirements related to attainment of the NAAQS.

Differences Between a Clean Data Determination and a Redesignation to Attainment

  • The determination of attainment (Clean Data Determination) is not equivalent to a redesignation, and the state must still meet the statutory requirements for redesignation in order to be redesignated to attainment. 
  • A determination of attainment for purposes of the Clean Data Policy/regulations is also not linked to any particular attainment deadline, and is not necessarily equivalent to a determination that an area has attained the standard by its applicable attainment deadline, e.g., under section 181(b).

Clean Data Policy Regulations

  • Under EPA's Clean Data Policy and the regulations that embody it: 

Clean Data Policy Guidance

For More Information About EPA Actions on Redesignation and CDP

See the EPA Green Book for comprehensive nonattainment area information for criteria pollutants. This website includes current area, state and county nonattainment and classification status, clean data determinations, redesignations, links to associated Federal Register Notices, GIS maps, and downloadable shapefiles and data exports.