(a) Extreme O3 nonattainment areas.
(1) A State or authorized governing body for any extreme O3 nonattainment area shall submit a plan revision to implement an EIP, in accordance with the requirements of this part, pursuant to section 182(g)(5) of the Act, if:
(i) A required milestone compliance demonstration is not submitted within the required period.
(ii) The Administrator determines that the area has not met any applicable milestone.
(2) The plan revision in paragraph (a)(1) of this section shall be submitted within 9 months after such failure or determination, and shall be sufficient, in combination with other elements of the SIP, to achieve the next milestone.
(b) Serious CO nonattainment areas.
(1) A State or authorized governing body for any serious CO nonattainment area shall submit a plan revision to implement an EIP, in accordance with the requirements of this part, if:
(i) A milestone demonstration is not submitted within the required period, pursuant to section 187(d) of the Act.
(ii) The Administrator notifies the State, pursuant to section 187(d) of the Act, that a milestone has not been met.
(iii) The Administrator determines, pursuant to section 186(b)(2) of the Act that the NAAQS for CO has not been attained by the applicable date for that area. Such revision shall be submitted within 9 months after such failure or determination.
(2) Submittals made pursuant to paragraphs (b)(1) (i) and (ii) of this section shall be sufficient, together with a transportation control program, to achieve the specific annual reductions in CO emissions set forth in the implementation plan by the attainment date. Submittals made pursuant to paragraph (b)(1)(iii) of this section shall be adequate, in combination with other elements of the revised plan, to reduce the total tonnage of emissions of CO in the area by at least 5 percent per year in each year after approval of the plan revision and before attainment of the NAAQS for CO.
(c) Serious and severe O3 nonattainment areas. If a State, for any serious or severe O3 nonattainment area, elects to implement an EIP in the circumstances set out in section 182(g)(3) of the Act, the State shall submit a plan revision to implement the program in accordance with the requirements of this part. If the option to implement an EIP is elected, a plan revision shall be submitted within 12 months after the date required for election, and shall be sufficient, in combination with other elements of the SIP, to achieve the next milestone.
(d) Any nonattainment or attainment area. Any State may at any time submit a plan or plan revision to implement a discretionary EIP, in accordance with the requirements of this part, pursuant to sections 110(a)(2)(A) and 172(c)(6) and other applicable provisions of the Act concerning SIP submittals. The plan revision shall not interfere with any applicable requirement concerning attainment and RFP, or any other applicable requirements of the Act.