40 CFR 51.150 - Classification of regions for episode plans.
(a) This section continues the classification system for episode plans. Each region is classified separately with respect to each of the following pollutants: Sulfur oxides, particulate matter, carbon monoxide, nitrogen dioxide, and ozone.
(b)Priority I Regions means any area with greater ambient concentrations than the following:
(1) Sulfur dioxide - 100 µg/m 3 (0.04 ppm) annual arithmetic mean; 455 µg/m 3 (0.17 ppm) 24-hour maximum.
(2) Particulate matter - 95 µg/m 3 annual geometric mean; 325 µg/m 3 24-hour maximum.
(3) Carbon monoxide - 55 mg/m 3 (48 ppm) 1-hour maximum; 14 mg/m 3 (12 ppm) 8-hour maximum.
(4) Nitrogen dioxide - 100 µg/m 3 (0.06 ppm) annual arithmetic mean.
(5) Ozone - 195 µg/m 3 (0.10 ppm) 1-hour maximum.
(c)Priority IA Region means any area which is Priority I primarily because of emissions from a single point source.
(d)Priority II Region means any area which is not a Priority I region and has ambient concentrations between the following:
(1) Sulfur Dioxides - 60-100 µg/m 3 (0.02-0.04 ppm) annual arithmetic mean; 260-445 µg/m 3 (0.10-0.17 ppm) 24-hour maximum; any concentration above 1,300 µg/m 3 (0.50 ppm) three-hour average.
(2) Particulate matter - 60-95 µg/m 3 annual geometric mean; 150-325 µg/m 3 24-hour maximum.
(f) Areas which do not meet the above criteria are classified Priority III.