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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.

Show
The worst-hit part of each metro: its highest credible monitor each day.
Rank City Worst day When Air event Population
1 Portland, OR-WA 513.4 µg/m³ Sep 13, 2020 Wildfire smoke Agency determination 2,537,904
2 Spokane, WA 396.8 µg/m³ Sep 13, 2020 Wildfire smoke Agency determination 604,962
3 Toledo, OH 387.8 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 601,396
4 Chicago, IL-IN-WI 330.9 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 9,408,576
5 Detroit, MI 320.6 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 4,400,578
6 Grand Rapids, MI 316.5 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 1,178,826
7 El Paso, TX 288.5 µg/m³ Apr 1, 2025 Dust High confidence 879,392
8 Milwaukee, WI 282.3 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 1,574,452
9 Sacramento, CA 265.7 µg/m³ Aug 28, 2021 Wildfire smoke EPA monitor flag 2,463,127
10 Allentown, PA-NJ 258.9 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 886,418
11 Seattle, WA 255.9 µg/m³ Oct 19, 2022 Wildfire smoke EPA monitor flag 4,145,494
12 Philadelphia, PA-NJ-DE-MD 240.8 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 6,330,422
13 San Diego, CA 239.2 µg/m³ Oct 27, 2003 Wildfire smoke EPA monitor flag 3,298,799
14 Cleveland, OH 224 µg/m³prov Jul 17, 2026 Wildfire smoke Agency determination 2,171,877
15 Scranton, PA 217.7 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 574,009
16 Phoenix, AZ 210.3 µg/m³ Jan 1, 2025 Fireworks EPA monitor flag 5,186,958
17 New York, NY-NJ-PA 203.5 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 19,940,274
18 Fresno, CA 199.3 µg/m³ Sep 16, 2020 Wildfire smoke Agency determination 1,189,557
19 Columbus, OH 197.2 µg/m³prov Jul 17, 2026 Wildfire smoke Agency determination 2,225,377
20 San Francisco, CA 195.4 µg/m³ Nov 16, 2018 Wildfire smoke EPA monitor flag 4,648,486
21 Madison, WI 192.7 µg/m³ Jun 28, 2023 Wildfire smoke Agency determination 707,606
22 Pittsburgh, PA 190.4 µg/m³prov Jul 17, 2026 Wildfire smoke Agency determination 2,429,917
23 Stockton, CA 188 µg/m³ Nov 16, 2018 Wildfire smoke EPA monitor flag 816,108
24 Indianapolis, IN 183.7 µg/m³ Jun 28, 2023 Wildfire smoke Agency determination 2,174,833
25 Syracuse, NY 182.6 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 655,189
26 Harrisburg, PA 180 µg/m³ Jun 8, 2023 Wildfire smoke Agency determination 615,361
27 Minneapolis, MN-WI 175.6 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 3,757,952
28 Los Angeles, CA 175 µg/m³ Jul 5, 2020 Fireworks EPA monitor flag 12,927,614
29 Washington, DC-VA-MD-WV 170.8 µg/m³prov Jul 17, 2026 Wildfire smoke Agency determination 6,436,489
30 Bridgeport, CT 166.6 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 972,679
31 Akron, OH 164.2 µg/m³prov Jul 17, 2026 Wildfire smoke Agency determination 702,209
32 Bakersfield, CA 158.6 µg/m³ Aug 22, 2020 Wildfire smoke EPA monitor flag 922,529
33 San Jose, CA 138.4 µg/m³ Nov 16, 2018 Wildfire smoke EPA monitor flag 1,995,484
34 Tampa, FL 137.3 µg/m³ May 11, 2007 Wildfire smoke EPA monitor flag 3,424,560
35 New Haven, CT 132.5 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 576,718
36 Buffalo, NY 131 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 1,160,172
37 Urban Honolulu, HI 130.1 µg/m³ Dec 31, 2000 Fireworks EPA monitor flag 998,747
38 Provo, UT 129.5 µg/m³ Jan 23, 2013 Temperature inversion High confidence 760,531
39 Dayton, OH 128.6 µg/m³ Jun 28, 2023 Wildfire smoke Agency determination 821,740
40 Greenville, SC 127.3 µg/m³ Nov 14, 2016 Wildfire smoke Agency determination 996,680
41 San Antonio, TX 126.1 µg/m³ Jan 1, 2003 Fireworks Likely 2,763,006
42 Baltimore, MD 125.3 µg/m³ Jun 8, 2023 Wildfire smoke Agency determination 2,859,024
43 Des Moines, IA 123.5 µg/m³ Jul 4, 2020 Fireworks EPA monitor flag 753,913
44 Riverside, CA 121.4 µg/m³ Nov 5, 1999 Temperature inversion Possible 4,744,214
45 Cincinnati, OH-KY-IN 121.1 µg/m³ Jun 28, 2023 Wildfire smoke Agency determination 2,302,815
46 Wichita, KS 120.1 µg/m³ Apr 5, 2024 Prescribed fire EPA monitor flag 661,217
47 Oxnard, CA 116 µg/m³ Oct 27, 2003 Wildfire smoke EPA monitor flag 835,427
48 Deltona, FL 114.3 µg/m³ May 9, 2007 Wildfire smoke EPA monitor flag 739,516
49 Houston, TX 110.6 µg/m³ Jan 1, 2020 Fireworks Possible 7,796,182
50 Charleston, SC 110.1 µg/m³ Jan 28, 2026 Wildfire smoke EPA monitor flag 869,940
51 Richmond, VA 109.6 µg/m³prov Jul 17, 2026 Wildfire smoke Agency determination 1,370,165
52 New Orleans, LA 108.2 µg/m³ Jan 1, 2024 Mixed causes EPA monitor flag 966,230
53 Chattanooga, TN-GA 105.7 µg/m³ Nov 14, 2016 Wildfire smoke Agency determination 588,050
54 Albany, NY 105.5 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 913,485
55 Rochester, NY 103.4 µg/m³prov Jul 16, 2026 Wildfire smoke Agency determination 1,057,218
56 Las Vegas, NV 100.7 µg/m³ Aug 7, 2021 Wildfire smoke EPA monitor flag 2,398,871
57 Louisville/Jefferson County, KY-IN 100.6 µg/m³ Jul 4, 2002 Fireworks Possible 1,394,234
58 Ogden, UT 100.2 µg/m³ Feb 7, 2002 Winter inversion Corroborated 667,681
59 Raleigh, NC 99 µg/m³ Jun 12, 2008 Wildfire smoke EPA monitor flag 1,562,009
60 Denver, CO 95.6 µg/m³ May 19, 2023 Wildfire smoke Agency determination 3,052,498
61 Salt Lake City, UT 94.2 µg/m³ Feb 16, 2004 Temperature inversion Likely 1,300,762
62 Miami, FL 91.7 µg/m³ Jun 3, 2011 Wildfire smoke Likely 6,457,988
63 Boise City, ID 89.5 µg/m³ Aug 31, 2024 Wildfire smoke Agency determination 845,877
64 Knoxville, TN 89.4 µg/m³ Nov 8, 2016 Wildfire smoke Agency determination 957,608
65 St. Louis, MO-IL 88.8 µg/m³ Jul 4, 2002 Fireworks Documented 2,811,927
66 Virginia Beach, VA-NC 88.4 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 1,794,278
67 Jacksonville, FL 87.9 µg/m³ May 17, 2007 Wildfire smoke EPA monitor flag 1,760,548
68 Columbia, SC 87.7 µg/m³ Nov 15, 2016 Wildfire smoke Agency determination 870,193
69 Charlotte, NC-SC 84.5 µg/m³ Nov 3, 2000 Wildfire smoke EPA monitor flag 2,883,370
70 Augusta, GA-SC 84.3 µg/m³ Nov 11, 2016 Wildfire smoke Agency determination 636,760
71 Albuquerque, NM 84 µg/m³ Aug 8, 2021 Wildfire smoke Agency determination 926,303
72 Orlando, FL 81 µg/m³ May 9, 2007 Wildfire smoke EPA monitor flag 2,940,513
73 Atlanta, GA 80 µg/m³ Jul 21, 1999 Cause not established after standard review Review complete 6,411,149
74 Tulsa, OK 79.6 µg/m³ Mar 8, 2021 Wildfire smoke Corroborated 1,059,803
75 Springfield, MA 78.4 µg/m³ Jul 1, 2002 Regional secondary PM Possible 464,151
76 Hartford, CT 77.6 µg/m³ Jun 7, 2023 Wildfire smoke Agency determination 1,169,048
77 Providence, RI-MA 77.1 µg/m³ Jul 7, 2002 Wildfire smoke EPA monitor flag 1,700,901
78 Worcester, MA-CT 76 µg/m³ Jul 7, 2002 Wildfire smoke EPA monitor flag 881,248
79 Lakeland, FL 75.5 µg/m³ Nov 2, 2000 Cause not established after standard review Review complete 852,878
80 Birmingham, AL 75.2 µg/m³ Oct 25, 2000 Stagnant pollution mixture Possible 1,192,583
81 Baton Rouge, LA 74.1 µg/m³ Feb 24, 2007 Cause not established after standard review Review complete 882,652
82 Dallas, TX 72.3 µg/m³ Mar 14, 2025 Mixed causes Likely 8,344,032
83 Omaha, NE-IA 72.1 µg/m³prov Jul 4, 2026 Fireworks Corroborated 1,001,010
84 Durham, NC 71.7 µg/m³ Jun 12, 2008 Wildfire smoke EPA monitor flag 620,522
85 Kansas City, MO-KS 71.4 µg/m³ Mar 13, 2003 Regional secondary PM Possible 2,253,579
86 Boston, MA-NH 70.1 µg/m³ Aug 25, 1999 Cause not established after standard review Review complete 5,025,517
87 Winston, NC 69.7 µg/m³ Nov 3, 2000 Wildfire smoke EPA monitor flag 705,187
88 Greensboro, NC 68.6 µg/m³ Jun 13, 2008 Wildfire smoke EPA monitor flag 800,722
89 McAllen, TX 64 µg/m³ Jun 27, 2020 Dust Agency determination 914,820
90 Nashville, TN 61.1 µg/m³ Oct 19, 2005 Prescribed fire Possible 2,150,553
91 Austin, TX 60.3 µg/m³ Jun 27, 2020 Dust Agency determination 2,550,637
92 Colorado Springs, CO 60.1 µg/m³ May 20, 2023 Wildfire smoke Agency determination 777,634
93 Oklahoma City, OK 59.8 µg/m³ Mar 14, 2025 Mixed causes EPA monitor flag 1,497,821
94 Memphis, TN-MS-AR 57.9 µg/m³ Jul 5, 2020 Fireworks EPA monitor flag 1,339,345
95 Tucson, AZ 56.2 µg/m³ Nov 5, 1999 Cause not established after standard review Review complete 1,080,149
96 North Port, FL 52.5 µg/m³ Dec 20, 1999 Cause not established after standard review Review complete 934,956
97 Little Rock, AR 50.5 µg/m³ Mar 15, 2025 Dust EPA monitor flag 769,258
98 Jackson, MS 49.4 µg/m³ Jun 24, 2005 Regional secondary PM Likely 606,178
99 Palm Bay, FL 47.1 µg/m³ Oct 3, 2023 Wildfire smoke EPA monitor flag 658,447
100 Cape Coral, FL 44.7 µg/m³ Sep 16, 2005 Temperature inversion Possible 860,959