Historical PM2.5 records
How bad has the air been where you live?
The worst air quality days on record for the 100 most populous US metro areas, ranked by the worst-hit area's daily PM2.5 from EPA monitors. These records include smoke, fireworks, dust, inversions, and other causes; this ranking does not attribute them to wildfire. Pick a city.
How this is measured sources, the daily measure, and coverage
Source. Finalized daily PM2.5 from the U.S. EPA Air Quality System (AQS), back to 1999. Recent days EPA has not yet certified use preliminary AirNow readings, labelled provisional and re-ranked once certified.
The number. "Worst area" is each metro's highest credible monitor each day, with lone bad-monitor spikes dropped (the raw single-monitor max before that filter is in the data but not charted); "Metro average" averages every monitor. The unit choice re-reads the same value as µg/m³, cigarette-equivalents (PM2.5 ÷ 22, Berkeley Earth), or the EPA 2024 PM2.5 AQI.
Coverage. The 100 most populous US metro areas (CBSAs) that have an EPA monitoring record (1,116 monitors in all), ranked here by their worst day. Metro population is from the U.S. Census Bureau Population Estimates (Vintage 2024). A metro with a thin record is shown with a note rather than dropped.
| Rank | City | Worst day | When | Population |
|---|---|---|---|---|
| 1 | Portland, OR-WA | 513.4 µg/m³ | Sep 13, 2020 | 2,537,904 |
| 2 | Spokane, WA | 396.8 µg/m³ | Sep 13, 2020 | 604,962 |
| 3 | Toledo, OH | 387.8 µg/m³prov | Jul 16, 2026 | 601,396 |
| 4 | Chicago, IL-IN-WI | 330.9 µg/m³prov | Jul 16, 2026 | 9,408,576 |
| 5 | Detroit, MI | 320.6 µg/m³prov | Jul 16, 2026 | 4,400,578 |
| 6 | Grand Rapids, MI | 316.5 µg/m³prov | Jul 16, 2026 | 1,178,826 |
| 7 | El Paso, TX | 288.5 µg/m³ | Apr 1, 2025 | 879,392 |
| 8 | Milwaukee, WI | 282.3 µg/m³prov | Jul 16, 2026 | 1,574,452 |
| 9 | Sacramento, CA | 265.7 µg/m³ | Aug 28, 2021 | 2,463,127 |
| 10 | Allentown, PA-NJ | 258.9 µg/m³ | Jun 7, 2023 | 886,418 |
| 11 | Seattle, WA | 255.9 µg/m³ | Oct 19, 2022 | 4,145,494 |
| 12 | Philadelphia, PA-NJ-DE-MD | 240.8 µg/m³ | Jun 7, 2023 | 6,330,422 |
| 13 | San Diego, CA | 239.2 µg/m³ | Oct 27, 2003 | 3,298,799 |
| 14 | Cleveland, OH | 224 µg/m³prov | Jul 17, 2026 | 2,171,877 |
| 15 | Scranton, PA | 217.7 µg/m³ | Jun 7, 2023 | 574,009 |
| 16 | Phoenix, AZ | 210.3 µg/m³ | Jan 1, 2025 | 5,186,958 |
| 17 | New York, NY-NJ-PA | 203.5 µg/m³ | Jun 7, 2023 | 19,940,274 |
| 18 | Fresno, CA | 199.3 µg/m³ | Sep 16, 2020 | 1,189,557 |
| 19 | Columbus, OH | 197.2 µg/m³prov | Jul 17, 2026 | 2,225,377 |
| 20 | San Francisco, CA | 195.4 µg/m³ | Nov 16, 2018 | 4,648,486 |
| 21 | Madison, WI | 192.7 µg/m³ | Jun 28, 2023 | 707,606 |
| 22 | Pittsburgh, PA | 190.4 µg/m³prov | Jul 17, 2026 | 2,429,917 |
| 23 | Stockton, CA | 188 µg/m³ | Nov 16, 2018 | 816,108 |
| 24 | Indianapolis, IN | 183.7 µg/m³ | Jun 28, 2023 | 2,174,833 |
| 25 | Syracuse, NY | 182.6 µg/m³ | Jun 7, 2023 | 655,189 |
| 26 | Harrisburg, PA | 180 µg/m³ | Jun 8, 2023 | 615,361 |
| 27 | Minneapolis, MN-WI | 175.6 µg/m³prov | Jul 16, 2026 | 3,757,952 |
| 28 | Los Angeles, CA | 175 µg/m³ | Jul 5, 2020 | 12,927,614 |
| 29 | Washington, DC-VA-MD-WV | 170.8 µg/m³prov | Jul 17, 2026 | 6,436,489 |
| 30 | Bridgeport, CT | 166.6 µg/m³ | Jun 7, 2023 | 972,679 |
| 31 | Akron, OH | 164.2 µg/m³prov | Jul 17, 2026 | 702,209 |
| 32 | Bakersfield, CA | 158.6 µg/m³ | Aug 22, 2020 | 922,529 |
| 33 | San Jose, CA | 138.4 µg/m³ | Nov 16, 2018 | 1,995,484 |
| 34 | Tampa, FL | 137.3 µg/m³ | May 11, 2007 | 3,424,560 |
| 35 | New Haven, CT | 132.5 µg/m³ | Jun 7, 2023 | 576,718 |
| 36 | Buffalo, NY | 131 µg/m³prov | Jul 16, 2026 | 1,160,172 |
| 37 | Urban Honolulu, HI | 130.1 µg/m³ | Dec 31, 2000 | 998,747 |
| 38 | Provo, UT | 129.5 µg/m³ | Jan 23, 2013 | 760,531 |
| 39 | Dayton, OH | 128.6 µg/m³ | Jun 28, 2023 | 821,740 |
| 40 | Greenville, SC | 127.3 µg/m³ | Nov 14, 2016 | 996,680 |
| 41 | San Antonio, TX | 126.1 µg/m³ | Jan 1, 2003 | 2,763,006 |
| 42 | Baltimore, MD | 125.3 µg/m³ | Jun 8, 2023 | 2,859,024 |
| 43 | Des Moines, IA | 123.5 µg/m³ | Jul 4, 2020 | 753,913 |
| 44 | Riverside, CA | 121.4 µg/m³ | Nov 5, 1999 | 4,744,214 |
| 45 | Cincinnati, OH-KY-IN | 121.1 µg/m³ | Jun 28, 2023 | 2,302,815 |
| 46 | Wichita, KS | 120.1 µg/m³ | Apr 5, 2024 | 661,217 |
| 47 | Oxnard, CA | 116 µg/m³ | Oct 27, 2003 | 835,427 |
| 48 | Deltona, FL | 114.3 µg/m³ | May 9, 2007 | 739,516 |
| 49 | Houston, TX | 110.6 µg/m³ | Jan 1, 2020 | 7,796,182 |
| 50 | Charleston, SC | 110.1 µg/m³ | Jan 28, 2026 | 869,940 |
| 51 | Richmond, VA | 109.6 µg/m³prov | Jul 17, 2026 | 1,370,165 |
| 52 | New Orleans, LA | 108.2 µg/m³ | Jan 1, 2024 | 966,230 |
| 53 | Chattanooga, TN-GA | 105.7 µg/m³ | Nov 14, 2016 | 588,050 |
| 54 | Albany, NY | 105.5 µg/m³ | Jun 7, 2023 | 913,485 |
| 55 | Rochester, NY | 103.4 µg/m³prov | Jul 16, 2026 | 1,057,218 |
| 56 | Las Vegas, NV | 100.7 µg/m³ | Aug 7, 2021 | 2,398,871 |
| 57 | Louisville/Jefferson County, KY-IN | 100.6 µg/m³ | Jul 4, 2002 | 1,394,234 |
| 58 | Ogden, UT | 100.2 µg/m³ | Feb 7, 2002 | 667,681 |
| 59 | Raleigh, NC | 99 µg/m³ | Jun 12, 2008 | 1,562,009 |
| 60 | Denver, CO | 95.6 µg/m³ | May 19, 2023 | 3,052,498 |
| 61 | Salt Lake City, UT | 94.2 µg/m³ | Feb 16, 2004 | 1,300,762 |
| 62 | Miami, FL | 91.7 µg/m³ | Jun 3, 2011 | 6,457,988 |
| 63 | Boise City, ID | 89.5 µg/m³ | Aug 31, 2024 | 845,877 |
| 64 | Knoxville, TN | 89.4 µg/m³ | Nov 8, 2016 | 957,608 |
| 65 | St. Louis, MO-IL | 88.8 µg/m³ | Jul 4, 2002 | 2,811,927 |
| 66 | Virginia Beach, VA-NC | 88.4 µg/m³ | Jun 7, 2023 | 1,794,278 |
| 67 | Jacksonville, FL | 87.9 µg/m³ | May 17, 2007 | 1,760,548 |
| 68 | Columbia, SC | 87.7 µg/m³ | Nov 15, 2016 | 870,193 |
| 69 | Charlotte, NC-SC | 84.5 µg/m³ | Nov 3, 2000 | 2,883,370 |
| 70 | Augusta, GA-SC | 84.3 µg/m³ | Nov 11, 2016 | 636,760 |
| 71 | Albuquerque, NM | 84 µg/m³ | Aug 8, 2021 | 926,303 |
| 72 | Orlando, FL | 81 µg/m³ | May 9, 2007 | 2,940,513 |
| 73 | Atlanta, GA | 80 µg/m³ | Jul 21, 1999 | 6,411,149 |
| 74 | Tulsa, OK | 79.6 µg/m³ | Mar 8, 2021 | 1,059,803 |
| 75 | Springfield, MA | 78.4 µg/m³ | Jul 1, 2002 | 464,151 |
| 76 | Hartford, CT | 77.6 µg/m³ | Jun 7, 2023 | 1,169,048 |
| 77 | Providence, RI-MA | 77.1 µg/m³ | Jul 7, 2002 | 1,700,901 |
| 78 | Worcester, MA-CT | 76 µg/m³ | Jul 7, 2002 | 881,248 |
| 79 | Lakeland, FL | 75.5 µg/m³ | Nov 2, 2000 | 852,878 |
| 80 | Birmingham, AL | 75.2 µg/m³ | Oct 25, 2000 | 1,192,583 |
| 81 | Baton Rouge, LA | 74.1 µg/m³ | Feb 24, 2007 | 882,652 |
| 82 | Dallas, TX | 72.3 µg/m³ | Mar 14, 2025 | 8,344,032 |
| 83 | Omaha, NE-IA | 72.1 µg/m³prov | Jul 4, 2026 | 1,001,010 |
| 84 | Durham, NC | 71.7 µg/m³ | Jun 12, 2008 | 620,522 |
| 85 | Kansas City, MO-KS | 71.4 µg/m³ | Mar 13, 2003 | 2,253,579 |
| 86 | Boston, MA-NH | 70.1 µg/m³ | Aug 25, 1999 | 5,025,517 |
| 87 | Winston, NC | 69.7 µg/m³ | Nov 3, 2000 | 705,187 |
| 88 | Greensboro, NC | 68.6 µg/m³ | Jun 13, 2008 | 800,722 |
| 89 | McAllen, TX | 64 µg/m³ | Jun 27, 2020 | 914,820 |
| 90 | Nashville, TN | 61.1 µg/m³ | Oct 19, 2005 | 2,150,553 |
| 91 | Austin, TX | 60.3 µg/m³ | Jun 27, 2020 | 2,550,637 |
| 92 | Colorado Springs, CO | 60.1 µg/m³ | May 20, 2023 | 777,634 |
| 93 | Oklahoma City, OK | 59.8 µg/m³ | Mar 14, 2025 | 1,497,821 |
| 94 | Memphis, TN-MS-AR | 57.9 µg/m³ | Jul 5, 2020 | 1,339,345 |
| 95 | Tucson, AZ | 56.2 µg/m³ | Nov 5, 1999 | 1,080,149 |
| 96 | North Port, FL | 52.5 µg/m³ | Dec 20, 1999 | 934,956 |
| 97 | Little Rock, AR | 50.5 µg/m³ | Mar 15, 2025 | 769,258 |
| 98 | Jackson, MS | 49.4 µg/m³ | Jun 24, 2005 | 606,178 |
| 99 | Palm Bay, FL | 47.1 µg/m³ | Oct 3, 2023 | 658,447 |
| 100 | Cape Coral, FL | 44.7 µg/m³ | Sep 16, 2005 | 860,959 |