(a) Unless EPA grants an extension under subpart R, compliance schedules designed to provide for attainment of a primary standard must—

(1) Provide for compliance with the applicable plan requirements as soon as practicable; or

(2) Provide for compliance no later than the date specified for attainment of the primary standard under;

(b) Unless EPA grants an extension under subpart R, compliance schedules designed to provide for attainment of a secondary standard must—

(1) Provide for compliance with the applicable plan requirements in a reasonable time; or

(2) Provide for compliance no later than the date specified for the attainment of the secondary standard under §51.110(c).