Code of Federal Regulations Title 40. Protection of Environment § 40.51.1307 Determining eligibility for 1–year attainment date extensions for an 8–hour ozone NAAQS under CAA section 181(a)(5)

(a) A nonattainment area will meet the requirement of CAA section 181(a)(5)(B) pertaining to 1–year extensions of the attainment date if:

(b) For purposes of paragraph (a)(1) of this section, the area's 4th highest daily maximum 8–hour average for a year shall be from the monitor with the highest 4th highest daily maximum 8–hour average for that year of all the monitors that represent that area.

(c) For purposes of paragraph (a)(2) of this section, the area's 4th highest daily maximum 8–hour value, averaged over both the original attainment year and the first extension year, shall be from the monitor in each year with the highest 4th highest daily maximum 8–hour average of all monitors that represent that area.