| SERIOUS |
| Clark County; Las Vegas planning area, NV |
| Imperial Valley, CA |
| Riverside, Los Angeles, Orange, & San Bernardino Counties; South Coast Air Basin, CA |
| San Joaquin Valley Air Basin, CA |
| Walla Walla County; Wallula, WA |
| Washoe County; Reno planning area, NV |
| |
| MODERATE |
| Ada County; Boise, ID |
| Adams, Denver, and Boulder Counties; Denver Metropolitan area, CO |
| Allegheny County; Liberty, Lincoln, Port Vue, Glassport, Clairton, PA |
| Anchorage; Eagle River, AK |
| Archuleta County; Pagosa Springs, CO |
| Aroostock County; City of Presque Isle, ME |
| Bonner County; The Sandpoint Area, ID |
| Brooke; Follansbee area, WV |
| Cook County; Lyons Township, IL |
| Cook County; Southeast Chicago, IL |
| Coso Junction, CA |
| Cuyahoga County, OH |
| Flathead County; Columbia Falls and vicinity, MT |
| Flathead County; Kalispell and vicinity, MT |
| Flathead County; Whitefish and vicinity, MT |
| Fremont County; Canon City Area, CO |
| Gila County (part): Payson, AZ |
| Hancock and Brooke Counties (Part); The city of Weirton, WV |
| Indian Wells, CA |
| Jackson County; Medford-Ashland (including White City), OR |
| Jefferson County, OH |
| Josephine County; Grants Pass, OR |
| Juneau; Mendenhall Valley area, AK |
| King County; Kent, WA |
| King County; Seattle, WA |
| Klamath Falls, OR |
| LaSalle County; Oglesby, IL |
| Lake County (part); Lakeview, OR |
| Lake County; Cities of East Chicago, Hammond, Whiting, and Gary, IN |
| Lane County; Eugene/Springfield, OR |
| Lincoln County; Libby and vicinity, MT |
| Madison County; Granite City Township and Nameoki Township, IL |
| Missoula, MT |
| Mohave County (part); Bullhead City, AZ |
| Mono County; Mammoth Lake planning area, CA |
| Mun. of Guaynabo, PR |
| New Haven County, CT |
| Ogden, UT |
| Olmsted County, MN |
| Pierce County; Tacoma, WA |
| Pima County; Ajo planning area, AZ |
| Pitkin County; Aspen, CO |
| Power-Bannock Counties; Portneuf Valley Area, ID |
| Prowers County; Lamar, CO |
| Ramsey County, MN |
| Routt County (part); Steamboat Springs, CO |
| Sacramento County, CA |
| Salt Lake County, UT |
| San Miguel County; Telluride, CO |
| Sanders County (part); Thompson Falls and vicinity, MT |
| Sheridan County; City of Sheridan, WY |
| Shoshone County; City of Pinehurst, ID |
| Shoshone County; Pinehurst Expansion Area, ID |
| Silver Bow County; Butte, MT |
| Spokane County, WA |
| Thurston County; Cities of Olympia, Tumwater, and Lacey, WA |
| Union County; LaGrande, OR |
| Utah County, UT |
| Vermillion County; Part of Clinton Township, IN |
| Wayne County, MI |
| Yakima County, WA |
