| SERIOUS |
| Clark Co, NV |
| Coachella Valley, CA |
| East Kern Co, CA |
| Imperial Valley, CA |
| Los Angeles South Coast Air Basin, CA |
| Owens Valley, CA |
| Phoenix, AZ |
| Washoe Co, NV |
| |
| MODERATE |
| Ajo (Pima County), AZ |
| Anthony, NM |
| Bonner Co (Sandpoint), ID |
| Butte, MT |
| Columbia Falls, MT |
| Eagle River, AK |
| El Paso Co, TX |
| Eugene-Springfield, OR |
| Flathead County; Whitefish and vicinity, MT |
| Fort Hall Indian Reservation, ID |
| Hayden AZ |
| Juneau, AK |
| Kalispell, MT |
| Lame Deer, MT |
| Lane Co, OR |
| Libby, MT |
| Mammoth Lake, CA |
| Miami, AZ |
| Missoula, MT |
| Mono Basin, CA |
| New York Co, NY |
| Nogales, AZ |
| Ogden, UT |
| Paul Spur/Douglas (Cochise County), AZ |
| Pinehurst, ID |
| Polson, MT |
| Rillito, AZ |
| Ronan, MT |
| Sacramento Co, CA |
| Salt Lake Co, UT |
| San Bernardino Co, CA |
| Sanders County (part);Thompson Falls and vicinity, MT |
| Sheridan, WY |
| Shoshone Co, ID |
| Trona, CA |
| Utah Co, UT |
| West Pinal, AZ |
| Yuma, AZ |
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