One principal source of EPA guidance with respect to redesignations to attainment can be found in a memorandum entitled "Procedures for Processing Requests to Redesignate Areas to Attainment (PDF)" (13 pp, 812k) John Calcagni, Director, Air Quality Management Division, September 4, 1992. It notes, for example, that, for the purposes of redesignation, 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. For the purposes of evaluating a redesignation request, the EPA will not need to consider the required SIP elements that became due after submittal of the redesignation request. However, such requirements remain due until EPA completes final action approving a redesignation request.
See the EPA Green Book website 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.