40 C.F.R. § 52.121
Classification of regions
The Arizona plan is evaluated on the basis of the following classifications:
| AQCR (constituent counties) | Classifications | ||||
|---|---|---|---|---|---|
| PM | SOX | NO2 | CO | O3 | |
| Maricopa Intrastate (Maricopa) | I | III | III | I | I |
| Pima Intrastate (Pima) | I | III | III | III | III |
| Northern Arizona Intrastate (Apache, Coconino, Navajo, Yavapai) | I | III | III | III | III |
| Mohave-Yuma Intrastate (La Paz, Mohave, Yuma) | I | III | III | III | III |
| Central Arizona Intrastate (Gila, Pinal) | I | IA | III | III | I |
| Southeast Arizona Intrastate (Cochise, Graham, Greenlee, Santa Cruz) | I | IA | III | III | III |