Metro areas: Unhealthy Air Days
EPA monitor data through 2025 · Updated August 13, 2026
456 U.S. metropolitan areas with at least 10 well-monitored years, ranked by days above an Air Quality Index of 100. Riverside-San Bernardino-Ontario, CA recorded the most, at 136 days in 2025.
| Metro area | Unhealthy days | Pre-2013 rules | Good days | Main driver | Year |
|---|---|---|---|---|---|
| Riverside-San Bernardino-Ontario, CA | 136 | 108 | 27 | ozone | 2025 |
| Los Angeles-Long Beach-Anaheim, CA | 99 | 71 | 39 | ozone | 2025 |
| Bakersfield, CA | 63 | 28 | 64 | ozone | 2025 |
| El Paso, TX | 63 | 55 | 66 | fine particles | 2025 |
| Phoenix-Mesa-Scottsdale, AZ | 56 | 39 | 24 | ozone | 2025 |
| Las Cruces, NM | 48 | 38 | 100 | fine particles | 2025 |
| Houston-The Woodlands-Sugar Land, TX | 46 | 33 | 37 | ozone | 2025 |
| Dallas-Fort Worth-Arlington, TX | 45 | 29 | 103 | ozone | 2025 |
| El Centro, CA | 45 | 32 | 101 | ozone | 2025 |
| Visalia-Porterville, CA | 43 | 15 | 88 | ozone | 2025 |
| Fresno, CA | 34 | 18 | 105 | ozone | 2025 |
| Chicago-Naperville-Elgin, IL-IN-WI | 32 | 24 | 109 | ozone | 2025 |
| San Diego-Carlsbad, CA | 32 | 14 | 65 | ozone | 2025 |
| Las Vegas-Henderson-Paradise, NV | 25 | 13 | 114 | ozone | 2025 |
| New York-Newark-Jersey City, NY-NJ-PA | 25 | 12 | 154 | ozone | 2025 |
| Carlsbad-Artesia, NM | 23 | 10 | 198 | ozone | 2025 |
| Duluth, MN-WI | 23 | 18 | 242 | fine particles | 2025 |
| Albuquerque, NM | 21 | 19 | 91 | fine particles | 2025 |
| Bridgeport-Stamford-Norwalk, CT | 21 | 13 | 236 | ozone | 2025 |
| Fairbanks, AK | 20 | 17 | 206 | fine particles | 2025 |
| Deming, NM | 18 | 18 | 305 | ozone and fine particles equally | 2025 |
| Milwaukee-Waukesha-West Allis, WI | 18 | 11 | 219 | fine particles | 2025 |
| Bemidji, MN | 17 | 13 | 287 | fine particles | 2025 |
| Denver-Aurora-Lakewood, CO | 17 | 3 | 106 | ozone | 2025 |
| Salt Lake City, UT | 17 | 5 | 122 | ozone | 2025 |
| Brainerd, MN | 16 | 14 | 271 | fine particles | 2025 |
| Detroit-Warren-Dearborn, MI | 16 | 10 | 132 | fine particles | 2025 |
| Cincinnati, OH-KY-IN | 15 | 8 | 95 | ozone | 2025 |
| Payson, AZ | 15 | 7 | 227 | ozone | 2025 |
| St. Louis, MO-IL | 15 | 11 | 114 | ozone | 2025 |
| Holland, MI | 14 | 3 | 233 | ozone | 2025 |
| Wenatchee, WA | 14 | 12 | 254 | fine particles | 2025 |
| Bishop, CA | 13 | 7 | 136 | ozone | 2025 |
| Bismarck, ND | 13 | 9 | 280 | fine particles | 2025 |
| New Haven-Milford, CT | 13 | 7 | 245 | ozone | 2025 |
| Philadelphia-Camden-Wilmington, PA-NJ-DE-MD | 13 | 6 | 151 | ozone | 2025 |
| Green Bay, WI | 12 | 9 | 264 | fine particles | 2025 |
| Michigan City-La Porte, IN | 12 | 7 | 230 | ozone | 2025 |
| Buffalo-Cheektowaga-Niagara Falls, NY | 11 | 4 | 233 | fine particles | 2025 |
| Eau Claire, WI | 11 | 8 | 269 | fine particles | 2025 |
| Fargo, ND-MN | 11 | 10 | 276 | fine particles | 2025 |
| Fort Collins, CO | 11 | 2 | 188 | ozone | 2025 |
| Hanford-Corcoran, CA | 11 | 1 | 126 | ozone | 2025 |
| Hartford-West Hartford-East Hartford, CT | 11 | 5 | 243 | ozone | 2025 |
| Laramie, WY | 11 | 11 | 211 | ozone and fine particles equally | 2025 |
| Minneapolis-St. Paul-Bloomington, MN-WI | 11 | 9 | 201 | fine particles | 2025 |
| San Antonio-New Braunfels, TX | 11 | 5 | 155 | ozone | 2025 |
| St. Cloud, MN | 11 | 7 | 271 | fine particles | 2025 |
| Kansas City, MO-KS | 10 | 7 | 180 | ozone | 2025 |
| Louisville/Jefferson County, KY-IN | 10 | 7 | 161 | ozone | 2025 |
| Spokane-Spokane Valley, WA | 10 | 8 | 206 | fine particles | 2025 |
| Appleton, WI | 9 | 9 | 264 | fine particles | 2025 |
| Grand Rapids-Wyoming, MI | 9 | 7 | 153 | fine particles | 2025 |
| Toledo, OH | 9 | 6 | 173 | fine particles | 2025 |
| Torrington, CT | 9 | 5 | 297 | ozone | 2025 |
| Ann Arbor, MI | 8 | 5 | 253 | fine particles | 2025 |
| Ardmore, OK | 8 | 4 | 236 | ozone | 2025 |
| Brownsville-Harlingen, TX | 8 | 5 | 109 | fine particles | 2025 |
| Columbus, OH | 8 | 3 | 145 | ozone | 2025 |
| Corpus Christi, TX | 8 | 4 | 148 | fine particles | 2025 |
| Dickinson, ND | 8 | 5 | 302 | fine particles | 2025 |
| Hobbs, NM | 8 | 6 | 250 | fine particles | 2025 |
| Indianapolis-Carmel-Anderson, IN | 8 | 4 | 137 | ozone | 2025 |
| Lansing-East Lansing, MI | 8 | 5 | 264 | fine particles | 2025 |
| Norwich-New London, CT | 8 | 4 | 297 | ozone | 2025 |
| Oklahoma City, OK | 8 | 3 | 162 | ozone | 2025 |
| Oxnard-Thousand Oaks-Ventura, CA | 8 | 4 | 190 | ozone | 2025 |
| Rochester, MN | 8 | 6 | 239 | fine particles | 2025 |
| Rock Springs, WY | 8 | 8 | 266 | ozone and fine particles equally | 2025 |
| Tucson, AZ | 8 | 7 | 123 | ozone and fine particles equally | 2025 |
| Adrian, MI | 7 | 2 | 253 | fine particles | 2025 |
| Beaver Dam, WI | 7 | 6 | 264 | fine particles | 2025 |
| Cleveland-Elyria, OH | 7 | 1 | 155 | ozone | 2025 |
| Grants Pass, OR | 7 | 7 | 249 | fine particles | 2025 |
| Kalamazoo-Portage, MI | 7 | 5 | 224 | fine particles | 2025 |
| Madison, WI | 7 | 2 | 242 | fine particles | 2025 |
| Marshall, MN | 7 | 6 | 281 | fine particles | 2025 |
| Memphis, TN-MS-AR | 7 | 4 | 203 | ozone | 2025 |
| Ogden-Clearfield, UT | 7 | 2 | 204 | ozone | 2025 |
| Rochester, NY | 7 | 4 | 271 | fine particles | 2025 |
| San Luis Obispo-Paso Robles-Arroyo Grande, CA | 7 | 1 | 192 | ozone | 2025 |
| South Bend-Mishawaka, IN-MI | 7 | 1 | 241 | ozone | 2025 |
| Washington-Arlington-Alexandria, DC-VA-MD-WV | 7 | 4 | 217 | ozone | 2025 |
| Yuma, AZ | 7 | 6 | 197 | ozone | 2025 |
| Atlanta-Sandy Springs-Roswell, GA | 6 | 1 | 150 | ozone | 2025 |
| Austin-Round Rock, TX | 6 | 3 | 159 | ozone | 2025 |
| Bangor, ME | 6 | 3 | 300 | fine particles | 2025 |
| Baraboo, WI | 6 | 3 | 276 | fine particles | 2025 |
| Elkhart-Goshen, IN | 6 | 3 | 223 | fine particles | 2025 |
| Eugene, OR | 6 | 3 | 206 | fine particles | 2025 |
| Greeley, CO | 6 | 1 | 163 | ozone | 2025 |
| Jacksonville, FL | 6 | 4 | 158 | ozone and fine particles equally | 2025 |
| Portland-South Portland, ME | 6 | 3 | 270 | ozone and fine particles equally | 2025 |
| Rockford, IL | 6 | 3 | 244 | fine particles | 2025 |
| Trenton, NJ | 6 | 3 | 255 | ozone | 2025 |
| Albany-Schenectady-Troy, NY | 5 | 4 | 247 | fine particles | 2025 |
| Baltimore-Columbia-Towson, MD | 5 | 3 | 212 | ozone | 2025 |
| Boston-Cambridge-Newton, MA-NH | 5 | 2 | 259 | ozone | 2025 |
| Brookings, SD | 5 | 4 | 214 | fine particles | 2025 |
| Cedar Rapids, IA | 5 | 3 | 224 | fine particles | 2025 |
| Chattanooga, TN-GA | 5 | 5 | 186 | fine particles | 2025 |
| Columbus, GA-AL | 5 | 2 | 195 | fine particles | 2025 |
| Fort Wayne, IN | 5 | 0 | 208 | ozone | 2025 |
| Laredo, TX | 5 | 1 | 182 | ozone | 2025 |
| Pittsburgh, PA | 5 | 2 | 157 | ozone | 2025 |
| Sacramento--Roseville--Arden-Arcade, CA | 5 | 4 | 129 | ozone | 2025 |
| Springfield, MA | 5 | 2 | 279 | ozone | 2025 |
| Topeka, KS | 5 | 4 | 234 | fine particles | 2025 |
| Youngstown-Warren-Boardman, OH-PA | 5 | 2 | 210 | ozone | 2025 |
| Bloomington, IL | 4 | 3 | 241 | fine particles | 2025 |
| Burlington-South Burlington, VT | 4 | 2 | 321 | fine particles | 2025 |
| Cadillac, MI | 4 | 2 | 314 | fine particles | 2025 |
| Champaign-Urbana, IL | 4 | 2 | 240 | ozone and fine particles equally | 2025 |
| Dayton, OH | 4 | 3 | 208 | ozone | 2025 |
| Dover, DE | 4 | 2 | 276 | ozone | 2025 |
| Elmira, NY | 4 | 0 | 322 | ozone | 2012 |
| Iowa City, IA | 4 | 2 | 256 | fine particles | 2025 |
| Killeen-Temple, TX | 4 | 1 | 241 | ozone | 2025 |
| Lawton, OK | 4 | 3 | 238 | ozone | 2025 |
| Lewiston, ID-WA | 4 | 2 | 219 | fine particles | 2025 |
| Little Rock-North Little Rock-Conway, AR | 4 | 1 | 114 | ozone | 2025 |
| Manchester-Nashua, NH | 4 | 1 | 311 | fine particles | 2025 |
| McAllen-Edinburg-Mission, TX | 4 | 2 | 162 | ozone | 2025 |
| Peoria, IL | 4 | 3 | 214 | fine particles | 2025 |
| Pittsfield, MA | 4 | 2 | 285 | fine particles | 2025 |
| Providence-Warwick, RI-MA | 4 | 3 | 256 | ozone | 2025 |
| Sandpoint, ID | 4 | 2 | 205 | fine particles | 2025 |
| Sierra Vista-Douglas, AZ | 4 | 4 | 254 | ozone and fine particles equally | 2025 |
| Sioux Falls, SD | 4 | 2 | 294 | fine particles | 2025 |
| Springfield, MO | 4 | 2 | 229 | ozone and fine particles equally | 2025 |
| Syracuse, NY | 4 | 2 | 305 | fine particles | 2025 |
| Tulsa, OK | 4 | 1 | 181 | ozone | 2025 |
| Vernal, UT | 4 | 1 | 214 | ozone | 2025 |
| Watertown, SD | 4 | 3 | 284 | fine particles | 2025 |
| Wichita, KS | 4 | 1 | 183 | fine particles | 2025 |
| Akron, OH | 3 | 2 | 225 | ozone | 2025 |
| Allentown-Bethlehem-Easton, PA-NJ | 3 | 1 | 244 | ozone | 2025 |
| Anchorage, AK | 3 | 2 | 283 | fine particles | 2025 |
| Ashtabula, OH | 3 | 1 | 200 | ozone | 2025 |
| Barnstable Town, MA | 3 | 1 | 342 | ozone | 2025 |
| Baton Rouge, LA | 3 | 1 | 130 | ozone | 2025 |
| Bay City, MI | 3 | 3 | 252 | fine particles | 2025 |
| Bend-Redmond, OR | 3 | 3 | 326 | fine particles | 2025 |
| Boulder, CO | 3 | 1 | 214 | ozone | 2025 |
| Claremont-Lebanon, NH-VT | 3 | 1 | 305 | fine particles | 2025 |
| Clinton, IA | 3 | 2 | 217 | fine particles | 2025 |
| Coeur d'Alene, ID | 3 | 1 | 274 | fine particles | 2025 |
| Corning, NY | 3 | 2 | 305 | fine particles | 2025 |
| Decatur, IL | 3 | 2 | 237 | fine particles | 2025 |
| Ellensburg, WA | 3 | 1 | 292 | fine particles | 2025 |
| Flint, MI | 3 | 1 | 253 | ozone | 2025 |
| Greenfield Town, MA | 3 | 1 | 281 | fine particles | 2025 |
| Klamath Falls, OR | 3 | 2 | 235 | fine particles | 2025 |
| Kokomo, IN | 3 | 1 | 241 | ozone | 2025 |
| Lake Charles, LA | 3 | 0 | 227 | ozone | 2025 |
| Madera, CA | 3 | 1 | 184 | ozone | 2025 |
| McAlester, OK | 3 | 3 | 207 | fine particles | 2025 |
| Modesto, CA | 3 | 0 | 182 | ozone | 2025 |
| Moses Lake, WA | 3 | 2 | 291 | fine particles | 2025 |
| Nogales, AZ | 3 | 2 | 190 | fine particles | 2025 |
| Omaha-Council Bluffs, NE-IA | 3 | 2 | 227 | ozone | 2025 |
| Platteville, WI | 3 | 3 | 246 | fine particles | 2025 |
| Reading, PA | 3 | 3 | 249 | ozone | 2025 |
| Scranton--Wilkes-Barre--Hazleton, PA | 3 | 2 | 264 | fine particles | 2025 |
| Sioux City, IA-NE-SD | 3 | 1 | 227 | ozone | 2025 |
| Springfield, IL | 3 | 1 | 256 | fine particles | 2025 |
| Vineland-Bridgeton, NJ | 3 | 1 | 278 | ozone | 2025 |
| Waco, TX | 3 | 1 | 170 | ozone | 2025 |
| Warren, PA | 3 | 1 | 120 | fine particles | 2025 |
| Waterloo-Cedar Falls, IA | 3 | 2 | 191 | fine particles | 2025 |
| Yakima, WA | 3 | 3 | 226 | fine particles | 2025 |
| York-Hanover, PA | 3 | 1 | 217 | fine particles | 2025 |
| Augusta-Richmond County, GA-SC | 2 | 2 | 168 | fine particles | 2025 |
| Beaumont-Port Arthur, TX | 2 | 0 | 151 | ozone | 2025 |
| Bennington, VT | 2 | 1 | 302 | fine particles | 2025 |
| Berlin, NH-VT | 2 | 0 | 294 | ozone | 2025 |
| Birmingham-Hoover, AL | 2 | 1 | 157 | fine particles | 2025 |
| Canton-Massillon, OH | 2 | 1 | 194 | ozone and fine particles equally | 2025 |
| Davenport-Moline-Rock Island, IA-IL | 2 | 2 | 207 | fine particles | 2025 |
| Des Moines-West Des Moines, IA | 2 | 2 | 224 | fine particles | 2025 |
| Durango, CO | 2 | 0 | 220 | ozone | 2025 |
| East Stroudsburg, PA | 2 | 1 | 318 | fine particles | 2025 |
| Elko, NV | 2 | 2 | 314 | fine particles | 2025 |
| Flagstaff, AZ | 2 | 0 | 258 | ozone and fine particles equally | 2025 |
| Fort Smith, AR-OK | 2 | 2 | 258 | fine particles | 2025 |
| Gillette, WY | 2 | 2 | 271 | ozone and fine particles equally | 2025 |
| Glenwood Springs, CO | 2 | 2 | 247 | fine particles | 2025 |
| Indiana, PA | 2 | 1 | 273 | ozone and fine particles equally | 2025 |
| Joplin, MO | 2 | 2 | 305 | ozone and fine particles equally | 2025 |
| Keene, NH | 2 | 1 | 288 | fine particles | 2025 |
| Kennewick-Richland, WA | 2 | 1 | 289 | fine particles | 2025 |
| Lake Havasu City-Kingman, AZ | 2 | 2 | 331 | ozone and fine particles equally | 2025 |
| Lancaster, PA | 2 | 1 | 221 | ozone and fine particles equally | 2025 |
| Lebanon, PA | 2 | 0 | 235 | ozone | 2025 |
| Lewiston-Auburn, ME | 2 | 0 | 311 | fine particles | 2025 |
| Lubbock, TX | 2 | 2 | 314 | fine particles | 2025 |
| Medford, OR | 2 | 1 | 242 | fine particles | 2025 |
| Miami, OK | 2 | 1 | 196 | fine particles | 2025 |
| Muscatine, IA | 2 | 2 | 241 | fine particles | 2025 |
| New Orleans-Metairie, LA | 2 | 0 | 189 | ozone | 2025 |
| Odessa, TX | 2 | 2 | 259 | fine particles | 2025 |
| Orlando-Kissimmee-Sanford, FL | 2 | 0 | 254 | ozone | 2025 |
| Pahrump, NV | 2 | 2 | 338 | ozone and fine particles equally | 2025 |
| Ponca City, OK | 2 | 1 | 257 | fine particles | 2025 |
| Portland-Vancouver-Hillsboro, OR-WA | 2 | 1 | 255 | ozone | 2025 |
| Portsmouth, OH | 2 | 1 | 204 | fine particles | 2025 |
| Price, UT | 2 | 0 | 264 | ozone | 2025 |
| Prineville, OR | 2 | 1 | 266 | fine particles | 2025 |
| Reno, NV | 2 | 0 | 183 | ozone | 2025 |
| San Juan-Carolina-Caguas, PR | 2 | 0 | 211 | fine particles | 2025 |
| Sayre, PA | 2 | 0 | 291 | fine particles | 2025 |
| Springfield, OH | 2 | 1 | 221 | ozone | 2025 |
| St. Joseph, MO-KS | 2 | 2 | 205 | fine particles | 2025 |
| Tampa-St. Petersburg-Clearwater, FL | 2 | 2 | 185 | ozone | 2025 |
| Vineyard Haven, MA | 2 | 2 | 331 | ozone | 2025 |
| Wilmington, NC | 2 | 2 | 281 | fine particles | 2025 |
| Albany, GA | 1 | 1 | 209 | fine particles | 2025 |
| Albany, OR | 1 | 1 | 292 | fine particles | 2025 |
| Altoona, PA | 1 | 0 | 279 | ozone | 2025 |
| Atlantic City-Hammonton, NJ | 1 | 0 | 300 | ozone | 2025 |
| Bellingham, WA | 1 | 1 | 342 | fine particles | 2025 |
| Boise City, ID | 1 | 1 | 182 | fine particles | 2025 |
| Bucyrus, OH | 1 | 0 | 235 | ozone | 2010 |
| Charleston-North Charleston, SC | 1 | 0 | 220 | fine particles | 2025 |
| Cheyenne, WY | 1 | 0 | 274 | ozone | 2025 |
| Clarksville, TN-KY | 1 | 1 | 263 | fine particles | 2025 |
| Corsicana, TX | 1 | 0 | 216 | fine particles | 2025 |
| Dodge City, KS | 1 | 1 | 325 | ozone and fine particles equally | 2025 |
| Erie, PA | 1 | 1 | 280 | fine particles | 2025 |
| Evansville, IN-KY | 1 | 0 | 210 | ozone | 2025 |
| Florence, SC | 1 | 0 | 225 | fine particles | 2025 |
| Gaffney, SC | 1 | 0 | 161 | ozone | 2016 |
| Harrisburg-Carlisle, PA | 1 | 0 | 224 | ozone | 2025 |
| Homosassa Springs, FL | 1 | 1 | 258 | fine particles | 2025 |
| Houma-Thibodaux, LA | 1 | 0 | 237 | fine particles | 2025 |
| Jamestown-Dunkirk-Fredonia, NY | 1 | 0 | 319 | ozone | 2025 |
| Johnstown, PA | 1 | 0 | 272 | ozone | 2025 |
| Juneau, AK | 1 | 1 | 306 | fine particles | 2025 |
| Kalispell, MT | 1 | 0 | 269 | fine particles | 2025 |
| Kingston, NY | 1 | 0 | 320 | ozone | 2012 |
| Kingsville, TX | 1 | 0 | 62 | fine particles | 2025 |
| Knoxville, TN | 1 | 0 | 207 | ozone | 2025 |
| Lafayette-West Lafayette, IN | 1 | 0 | 247 | ozone | 2025 |
| Lima, OH | 1 | 1 | 236 | ozone | 2025 |
| Longview, TX | 1 | 0 | 316 | ozone | 2025 |
| Macon, GA | 1 | 1 | 156 | fine particles | 2025 |
| Miami-Fort Lauderdale-West Palm Beach, FL | 1 | 0 | 193 | fine particles | 2025 |
| Morgantown, WV | 1 | 0 | 220 | ozone | 2025 |
| Moscow, ID | 1 | 0 | 282 | fine particles | 2025 |
| Nashville-Davidson--Murfreesboro--Franklin, TN | 1 | 1 | 187 | ozone | 2025 |
| Ocala, FL | 1 | 0 | 246 | ozone | 2025 |
| Pensacola-Ferry Pass-Brent, FL | 1 | 0 | 238 | fine particles | 2025 |
| Pierre, SD | 1 | 0 | 333 | fine particles | 2025 |
| Pocatello, ID | 1 | 0 | 324 | fine particles | 2025 |
| Provo-Orem, UT | 1 | 1 | 206 | ozone and fine particles equally | 2025 |
| Rapid City, SD | 1 | 1 | 227 | ozone and fine particles equally | 2025 |
| Red Bluff, CA | 1 | 0 | 285 | ozone | 2025 |
| Redding, CA | 1 | 1 | 275 | fine particles | 2025 |
| Richmond, VA | 1 | 0 | 265 | ozone | 2025 |
| Rutland, VT | 1 | 1 | 284 | fine particles | 2025 |
| Salisbury, MD-DE | 1 | 0 | 301 | ozone | 2025 |
| Seattle-Tacoma-Bellevue, WA | 1 | 1 | 205 | fine particles | 2025 |
| Shelton, WA | 1 | 1 | 330 | fine particles | 2025 |
| Shreveport-Bossier City, LA | 1 | 0 | 252 | ozone | 2025 |
| Sonora, CA | 1 | 0 | 301 | ozone | 2025 |
| State College, PA | 1 | 0 | 271 | ozone | 2025 |
| Tallahassee, FL | 1 | 1 | 186 | fine particles | 2025 |
| Terre Haute, IN | 1 | 0 | 218 | fine particles | 2025 |
| Truckee-Grass Valley, CA | 1 | 0 | 290 | ozone | 2025 |
| Twin Falls, ID | 1 | 0 | 339 | fine particles | 2025 |
| Virginia Beach-Norfolk-Newport News, VA-NC | 1 | 0 | 285 | ozone | 2025 |
| Wabash, IN | 1 | 0 | 324 | ozone | 2025 |
| Weirton-Steubenville, WV-OH | 1 | 0 | 195 | ozone | 2025 |
| Wheeling, WV-OH | 1 | 1 | 186 | ozone and fine particles equally | 2025 |
| Williamsport, PA | 1 | 0 | 282 | ozone | 2025 |
| Worcester, MA-CT | 1 | 0 | 296 | ozone | 2025 |
| Aberdeen, WA | 0 | 0 | 355 | ozone and fine particles equally | 2025 |
| Amarillo, TX | 0 | 0 | 285 | ozone and fine particles equally | 2025 |
| Arkadelphia, AR | 0 | 0 | 352 | ozone and fine particles equally | 2025 |
| Asheville, NC | 0 | 0 | 258 | ozone and fine particles equally | 2025 |
| Athens, TN | 0 | 0 | 279 | ozone and fine particles equally | 2025 |
| Athens-Clarke County, GA | 0 | 0 | 211 | ozone and fine particles equally | 2025 |
| Billings, MT | 0 | 0 | 315 | ozone and fine particles equally | 2025 |
| Blacksburg-Christiansburg-Radford, VA | 0 | 0 | 343 | ozone and fine particles equally | 2025 |
| Bloomington, IN | 0 | 0 | 247 | ozone and fine particles equally | 2025 |
| Bowling Green, KY | 0 | 0 | 276 | ozone and fine particles equally | 2025 |
| Bozeman, MT | 0 | 0 | 358 | ozone and fine particles equally | 2025 |
| Bremerton-Silverdale, WA | 0 | 0 | 340 | ozone and fine particles equally | 2025 |
| Brunswick, GA | 0 | 0 | 255 | ozone and fine particles equally | 2025 |
| Butte-Silver Bow, MT | 0 | 0 | 310 | ozone and fine particles equally | 2025 |
| Cambridge, MD | 0 | 0 | 314 | ozone and fine particles equally | 2025 |
| Cape Coral-Fort Myers, FL | 0 | 0 | 279 | ozone and fine particles equally | 2025 |
| Carson City, NV | 0 | 0 | 313 | ozone and fine particles equally | 2025 |
| Casper, WY | 0 | 0 | 315 | ozone and fine particles equally | 2025 |
| Centralia, WA | 0 | 0 | 295 | ozone and fine particles equally | 2025 |
| Chambersburg-Waynesboro, PA | 0 | 0 | 277 | ozone and fine particles equally | 2025 |
| Charleston, WV | 0 | 0 | 281 | ozone and fine particles equally | 2025 |
| Charlotte-Concord-Gastonia, NC-SC | 0 | 0 | 168 | ozone and fine particles equally | 2025 |
| Charlottesville, VA | 0 | 0 | 294 | ozone and fine particles equally | 2025 |
| Chico, CA | 0 | 0 | 238 | ozone and fine particles equally | 2025 |
| Clearlake, CA | 0 | 0 | 362 | ozone and fine particles equally | 2025 |
| Cleveland, MS | 0 | 0 | 260 | ozone and fine particles equally | 2025 |
| Cleveland, TN | 0 | 0 | 262 | ozone and fine particles equally | 2012 |
| Coco, PR | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Coffeyville, KS | 0 | 0 | 0 | ozone and fine particles equally | 2011 |
| Colorado Springs, CO | 0 | 0 | 250 | ozone and fine particles equally | 2025 |
| Columbia, SC | 0 | 0 | 212 | ozone and fine particles equally | 2025 |
| Columbus, IN | 0 | 0 | 265 | ozone and fine particles equally | 2025 |
| Concord, NH | 0 | 0 | 206 | ozone and fine particles equally | 2025 |
| Corvallis, OR | 0 | 0 | 183 | ozone and fine particles equally | 2022 |
| Crestview-Fort Walton Beach-Destin, FL | 0 | 0 | 338 | ozone and fine particles equally | 2025 |
| Decatur, AL | 0 | 0 | 286 | ozone and fine particles equally | 2025 |
| Deltona-Daytona Beach-Ormond Beach, FL | 0 | 0 | 297 | ozone and fine particles equally | 2025 |
| Durham-Chapel Hill, NC | 0 | 0 | 261 | ozone and fine particles equally | 2025 |
| Eagle Pass, TX | 0 | 0 | 221 | ozone and fine particles equally | 2025 |
| El Dorado, AR | 0 | 0 | 51 | ozone and fine particles equally | 2025 |
| Elizabethtown-Fort Knox, KY | 0 | 0 | 223 | ozone and fine particles equally | 2025 |
| Enid, OK | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Espa¤ola, NM | 0 | 0 | 307 | ozone and fine particles equally | 2025 |
| Eureka-Arcata-Fortuna, CA | 0 | 0 | 285 | ozone and fine particles equally | 2025 |
| Evanston, WY | 0 | 0 | 269 | ozone and fine particles equally | 2025 |
| Fallon, NV | 0 | 0 | 294 | ozone and fine particles equally | 2025 |
| Farmington, NM | 0 | 0 | 248 | ozone and fine particles equally | 2025 |
| Fayetteville, NC | 0 | 0 | 251 | ozone and fine particles equally | 2025 |
| Fayetteville-Springdale-Rogers, AR-MO | 0 | 0 | 304 | ozone and fine particles equally | 2025 |
| Fernley, NV | 0 | 0 | 327 | ozone and fine particles equally | 2025 |
| Florence-Muscle Shoals, AL | 0 | 0 | 239 | ozone and fine particles equally | 2019 |
| Fort Payne, AL | 0 | 0 | 282 | ozone and fine particles equally | 2025 |
| Gadsden, AL | 0 | 0 | 223 | ozone and fine particles equally | 2025 |
| Gainesville, FL | 0 | 0 | 323 | ozone and fine particles equally | 2025 |
| Gainesville, GA | 0 | 0 | 210 | ozone and fine particles equally | 2025 |
| Gardnerville Ranchos, NV | 0 | 0 | 326 | ozone and fine particles equally | 2025 |
| Georgetown, SC | 0 | 0 | 91 | ozone and fine particles equally | 2019 |
| Gettysburg, PA | 0 | 0 | 262 | ozone and fine particles equally | 2025 |
| Grand Junction, CO | 0 | 0 | 241 | ozone and fine particles equally | 2025 |
| Great Falls, MT | 0 | 0 | 52 | ozone and fine particles equally | 2024 |
| Greensboro-High Point, NC | 0 | 0 | 272 | ozone and fine particles equally | 2025 |
| Greenville, NC | 0 | 0 | 321 | ozone and fine particles equally | 2025 |
| Greenville-Anderson-Mauldin, SC | 0 | 0 | 202 | ozone and fine particles equally | 2025 |
| Guayama, PR | 0 | 0 | 49 | ozone and fine particles equally | 2025 |
| Gulfport-Biloxi-Pascagoula, MS | 0 | 0 | 224 | ozone and fine particles equally | 2025 |
| Hagerstown-Martinsburg, MD-WV | 0 | 0 | 280 | ozone and fine particles equally | 2025 |
| Harrison, AR | 0 | 0 | 332 | ozone and fine particles equally | 2025 |
| Harrisonburg, VA | 0 | 0 | 292 | ozone and fine particles equally | 2025 |
| Hattiesburg, MS | 0 | 0 | 226 | ozone and fine particles equally | 2025 |
| Helena, MT | 0 | 0 | 261 | ozone and fine particles equally | 2025 |
| Hermiston-Pendleton, OR | 0 | 0 | 260 | ozone and fine particles equally | 2025 |
| Hickory-Lenoir-Morganton, NC | 0 | 0 | 250 | ozone and fine particles equally | 2025 |
| Hilo, HI | 0 | 0 | 314 | ozone and fine particles equally | 2025 |
| Huntington-Ashland, WV-KY-OH | 0 | 0 | 229 | ozone and fine particles equally | 2025 |
| Huntsville, AL | 0 | 0 | 263 | ozone and fine particles equally | 2025 |
| Idaho Falls, ID | 0 | 0 | 310 | ozone and fine particles equally | 2025 |
| Ithaca, NY | 0 | 0 | 335 | ozone and fine particles equally | 2025 |
| Jackson, MS | 0 | 0 | 167 | ozone and fine particles equally | 2025 |
| Jackson, WY-ID | 0 | 0 | 310 | ozone and fine particles equally | 2025 |
| Jasper, IN | 0 | 0 | 253 | ozone and fine particles equally | 2025 |
| Kahului-Wailuku-Lahaina, HI | 0 | 0 | 353 | ozone and fine particles equally | 2025 |
| Kapaa, HI | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Kingsport-Bristol-Bristol, TN-VA | 0 | 0 | 291 | ozone and fine particles equally | 2025 |
| La Crosse-Onalaska, WI-MN | 0 | 0 | 187 | ozone and fine particles equally | 2025 |
| La Grande, OR | 0 | 0 | 298 | ozone and fine particles equally | 2025 |
| Lafayette, LA | 0 | 0 | 234 | ozone and fine particles equally | 2025 |
| Lake City, FL | 0 | 0 | 209 | ozone and fine particles equally | 2025 |
| Lakeland-Winter Haven, FL | 0 | 0 | 345 | ozone and fine particles equally | 2025 |
| Lexington-Fayette, KY | 0 | 0 | 268 | ozone and fine particles equally | 2025 |
| Lincoln, NE | 0 | 0 | 242 | ozone and fine particles equally | 2025 |
| Logan, UT-ID | 0 | 0 | 241 | ozone and fine particles equally | 2025 |
| Longview, WA | 0 | 0 | 226 | ozone and fine particles equally | 2025 |
| Malone, NY | 0 | 0 | 194 | ozone and fine particles equally | 2019 |
| Manhattan, KS | 0 | 0 | 90 | ozone and fine particles equally | 2013 |
| Marshall, TX | 0 | 0 | 235 | ozone and fine particles equally | 2025 |
| Mason City, IA | 0 | 0 | 58 | ozone and fine particles equally | 2023 |
| Merced, CA | 0 | 0 | 186 | ozone and fine particles equally | 2025 |
| Missoula, MT | 0 | 0 | 298 | ozone and fine particles equally | 2025 |
| Mobile, AL | 0 | 0 | 260 | ozone and fine particles equally | 2025 |
| Monroe, LA | 0 | 0 | 227 | ozone and fine particles equally | 2025 |
| Montgomery, AL | 0 | 0 | 229 | ozone and fine particles equally | 2025 |
| Morehead City, NC | 0 | 0 | 337 | ozone and fine particles equally | 2025 |
| Mount Vernon, IL | 0 | 0 | 245 | ozone and fine particles equally | 2025 |
| Mount Vernon-Anacortes, WA | 0 | 0 | 354 | ozone and fine particles equally | 2025 |
| Muskogee, OK | 0 | 0 | 0 | ozone and fine particles equally | 2020 |
| Napa, CA | 0 | 0 | 108 | ozone and fine particles equally | 2021 |
| Naples-Immokalee-Marco Island, FL | 0 | 0 | 263 | ozone and fine particles equally | 2025 |
| New Castle, PA | 0 | 0 | 31 | ozone and fine particles equally | 2024 |
| New Philadelphia-Dover, OH | 0 | 0 | 0 | ozone and fine particles equally | 2012 |
| North Port-Sarasota-Bradenton, FL | 0 | 0 | 230 | ozone and fine particles equally | 2025 |
| Olympia-Tumwater, WA | 0 | 0 | 274 | ozone and fine particles equally | 2025 |
| Othello, WA | 0 | 0 | 315 | ozone and fine particles equally | 2025 |
| Ottawa-Peru, IL | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Owensboro, KY | 0 | 0 | 221 | ozone and fine particles equally | 2025 |
| Paducah, KY-IL | 0 | 0 | 271 | ozone and fine particles equally | 2025 |
| Palatka, FL | 0 | 0 | 349 | ozone and fine particles equally | 2025 |
| Palm Bay-Melbourne-Titusville, FL | 0 | 0 | 335 | ozone and fine particles equally | 2025 |
| Panama City, FL | 0 | 0 | 244 | ozone and fine particles equally | 2025 |
| Parkersburg-Vienna, WV | 0 | 0 | 236 | ozone and fine particles equally | 2025 |
| Point Pleasant, WV-OH | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Ponce, PR | 0 | 0 | 235 | ozone and fine particles equally | 2025 |
| Port Angeles, WA | 0 | 0 | 312 | ozone and fine particles equally | 2025 |
| Port St. Lucie, FL | 0 | 0 | 289 | ozone and fine particles equally | 2025 |
| Prescott, AZ | 0 | 0 | 238 | ozone and fine particles equally | 2025 |
| Pullman, WA | 0 | 0 | 317 | ozone and fine particles equally | 2025 |
| Quincy, IL-MO | 0 | 0 | 232 | ozone and fine particles equally | 2025 |
| Raleigh, NC | 0 | 0 | 242 | ozone and fine particles equally | 2025 |
| Richmond, IN | 0 | 0 | 0 | ozone and fine particles equally | 2016 |
| Riverton, WY | 0 | 0 | 254 | ozone and fine particles equally | 2025 |
| Roanoke, VA | 0 | 0 | 302 | ozone and fine particles equally | 2025 |
| Rocky Mount, NC | 0 | 0 | 308 | ozone and fine particles equally | 2025 |
| Rome, GA | 0 | 0 | 248 | ozone and fine particles equally | 2025 |
| Roseburg, OR | 0 | 0 | 21 | ozone and fine particles equally | 2022 |
| Salem, OH | 0 | 0 | 61 | ozone and fine particles equally | 2025 |
| Salem, OR | 0 | 0 | 292 | ozone and fine particles equally | 2025 |
| Salinas, CA | 0 | 0 | 314 | ozone and fine particles equally | 2025 |
| San Francisco-Oakland-Hayward, CA | 0 | 0 | 87 | ozone and fine particles equally | 2025 |
| San Jose-Sunnyvale-Santa Clara, CA | 0 | 0 | 333 | ozone and fine particles equally | 2025 |
| Santa Cruz-Watsonville, CA | 0 | 0 | 320 | ozone and fine particles equally | 2025 |
| Santa Fe, NM | 0 | 0 | 285 | ozone and fine particles equally | 2025 |
| Santa Maria-Santa Barbara, CA | 0 | 0 | 164 | ozone and fine particles equally | 2025 |
| Santa Rosa, CA | 0 | 0 | 365 | ozone and fine particles equally | 2025 |
| Savannah, GA | 0 | 0 | 214 | ozone and fine particles equally | 2025 |
| Sebastian-Vero Beach, FL | 0 | 0 | 319 | ozone and fine particles equally | 2025 |
| Sebring, FL | 0 | 0 | 347 | ozone and fine particles equally | 2025 |
| Seneca, SC | 0 | 0 | 0 | ozone and fine particles equally | 2020 |
| Sevierville, TN | 0 | 0 | 353 | ozone and fine particles equally | 2025 |
| Sheridan, WY | 0 | 0 | 320 | ozone and fine particles equally | 2025 |
| Show Low, AZ | 0 | 0 | 363 | ozone and fine particles equally | 2025 |
| Silver City, NM | 0 | 0 | 0 | ozone and fine particles equally | 2015 |
| Somerset, PA | 0 | 0 | 346 | ozone and fine particles equally | 2025 |
| Spartanburg, SC | 0 | 0 | 201 | ozone and fine particles equally | 2025 |
| St. George, UT | 0 | 0 | 274 | ozone and fine particles equally | 2025 |
| St. Marys, PA | 0 | 0 | 346 | ozone and fine particles equally | 2025 |
| Steamboat Springs, CO | 0 | 0 | 342 | ozone and fine particles equally | 2025 |
| Stockton-Lodi, CA | 0 | 0 | 219 | ozone and fine particles equally | 2025 |
| Tahlequah, OK | 0 | 0 | 263 | ozone and fine particles equally | 2017 |
| Taos, NM | 0 | 0 | 352 | ozone and fine particles equally | 2025 |
| The Dalles, OR | 0 | 0 | 315 | ozone and fine particles equally | 2025 |
| Tupelo, MS | 0 | 0 | 232 | ozone and fine particles equally | 2025 |
| Tuscaloosa, AL | 0 | 0 | 265 | ozone and fine particles equally | 2025 |
| Tyler, TX | 0 | 0 | 330 | ozone and fine particles equally | 2025 |
| Ukiah, CA | 0 | 0 | 269 | ozone and fine particles equally | 2025 |
| Urban Honolulu, HI | 0 | 0 | 355 | ozone and fine particles equally | 2025 |
| Utica-Rome, NY | 0 | 0 | 298 | ozone and fine particles equally | 2025 |
| Valdosta, GA | 0 | 0 | 187 | ozone and fine particles equally | 2025 |
| Vallejo-Fairfield, CA | 0 | 0 | 361 | ozone and fine particles equally | 2025 |
| Victoria, TX | 0 | 0 | 317 | ozone and fine particles equally | 2025 |
| Vincennes, IN | 0 | 0 | 320 | ozone and fine particles equally | 2025 |
| Walla Walla, WA | 0 | 0 | 290 | ozone and fine particles equally | 2025 |
| Walterboro, SC | 0 | 0 | 7 | ozone and fine particles equally | 2019 |
| Warner Robins, GA | 0 | 0 | 222 | ozone and fine particles equally | 2025 |
| Washington Court House, OH | 0 | 0 | 128 | ozone and fine particles equally | 2022 |
| Washington, IN | 0 | 0 | 0 | ozone and fine particles equally | 2021 |
| Washington, NC | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Watertown-Fort Drum, NY | 0 | 0 | 342 | ozone and fine particles equally | 2025 |
| Williston, ND | 0 | 0 | 0 | ozone and fine particles equally | 2025 |
| Winchester, VA-WV | 0 | 0 | 270 | ozone and fine particles equally | 2025 |
| Winston-Salem, NC | 0 | 0 | 152 | ozone and fine particles equally | 2025 |
| Yuba City, CA | 0 | 0 | 234 | ozone and fine particles equally | 2025 |
Metro areas with fewer than 10 years of near-complete monitoring are omitted; their series is too gappy to carry a trend. “Unhealthy days” means the Air Quality Index exceeded 100, the level at which EPA begins warning sensitive groups. The pre-2013 column applies the AQI rules in force before EPA's 2013 and 2015 revisions to the same monitor data, for comparison with older reports — why that matters.
Sources
- EPA AirData daily monitor files. Methods and validation.
- Download the full dataset.