(a) Nonattainment areas initially classified as Moderate. Upon a determination by the EPA that a Moderate PM2.5 nonattainment area has attained the PM2.5 NAAQS, the requirements for the state to submit an attainment demonstration, provisions demonstrating that reasonably available control measures (including reasonably available control technology for stationary sources) shall be implemented no later than 4 years following the date of designation of the area, reasonable further progress plan, quantitative milestones and quantitative milestone reports, and contingency measures for the area shall be suspended until such time as:

(1) The area is redesignated to attainment, after which such requirements are permanently discharged; or,

(2) The EPA determines that the area has re-violated the PM2.5 NAAQS, at which time the state shall submit such attainment plan elements for the Moderate nonattainment area by a future date to be determined by the EPA and announced through publication in the Federal Register at the time EPA determines the area is violating the PM2.5 NAAQS.

(b) Nonattainment areas reclassified as Serious. Upon a determination by the EPA that a Serious PM2.5 nonattainment area has attained the PM2.5 NAAQS, the requirements for the state to submit an attainment demonstration, reasonable further progress plan, quantitative milestones and quantitative milestone reports, and contingency measures for the area shall be suspended until such time as:

(1) The area is redesignated to attainment, after which such requirements are permanently discharged; or,

(2) The EPA determines that the area has re-violated the PM2.5 NAAQS, at which time the state shall submit such attainment plan elements for the Serious nonattainment area by a future date to be determined by the EPA and announced through publication in the Federal Register at the time the EPA determines the area is violating the PM2.5 NAAQS.