Wildfire smoke
2023 late-June Canadian wildfire-smoke episode
Daily PM2.5 peaked at 210.1 µg/m³ near Cleveland across 42 covered metros home to 97 million people. 4 metros recorded their worst day on record; 33 placed a top-ten day.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 7.6 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 735 million cigarettes. An awareness illustration of outdoor exposure at 22 µg/m³ per cigarette (Berkeley Earth), counting only the event's ranked days; not a medical dose.
Measured daily PM2.5 at EPA monitors, as cigarette-equivalents
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Episode peak
-- cigarettes
The smoke map's scale, replayed over this event: the surface interpolates between covered metros' daily records, framed to the affected region. Hover for a reading, click a metro to pin it to the card. Days a monitor did not report draw nothing.
What happened, in the record
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 13 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-26 through 2023-07-01 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 13 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-26 through 2023-07-01 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 13 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-26 through 2023-07-01 occurrence. Qualified supplie
Sequence: Milwaukee (Jun 26) → Madison (Jun 26) → Cleveland (Jun 27) → Indianapolis (Jun 27) → Chicago (Jun 27) → Grand Rapids (Jun 27) → Detroit (Jun 27) → Columbus (Jun 27) → Dayton (Jun 27) → Cincinnati (Jun 27) → +32 more metros
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Cleveland-Elyria, OH | 210.1 µg/m³ | 16.8 | Jun 28, 2023 | #3 of its top days |
| Milwaukee-Waukesha-West Allis, WI | 195.4 µg/m³ | 22.3 | Jun 27, 2023 | #2 of its top days |
| Madison, WI | 192.7 µg/m³ | 22.8 | Jun 28, 2023 | Worst day on record |
| Indianapolis-Carmel-Anderson, IN | 183.7 µg/m³ | 19.8 | Jun 28, 2023 | Worst day on record |
| Chicago-Naperville-Elgin, IL-IN-WI | 170.6 µg/m³ | 18.6 | Jun 28, 2023 | #2 of its top days |
| Pittsburgh, PA | 161.4 µg/m³ | 14.6 | Jun 29, 2023 | #2 of its top days |
| Akron, OH | 154.4 µg/m³ | 11.0 | Jun 28, 2023 | #2 of its top days |
| Grand Rapids-Wyoming, MI | 151.7 µg/m³ | 16.3 | Jun 27, 2023 | #3 of its top days |
| Detroit-Warren-Dearborn, MI | 150.4 µg/m³ | 17.2 | Jun 28, 2023 | #3 of its top days |
| Columbus, OH | 134.9 µg/m³ | 13.9 | Jun 28, 2023 | #3 of its top days |
| Dayton, OH | 128.6 µg/m³ | 12.9 | Jun 28, 2023 | Worst day on record |
| Cincinnati, OH-KY-IN | 121.1 µg/m³ | 11.5 | Jun 28, 2023 | Worst day on record |
| Louisville/Jefferson County, KY-IN | 100.4 µg/m³ | 4.6 | Jun 28, 2023 | #2 of its top days |
| Toledo, OH | 99.2 µg/m³ | 4.5 | Jun 29, 2023 | #3 of its top days |
| Harrisburg-Carlisle, PA | 97.2 µg/m³ | 10.2 | Jun 29, 2023 | #5 of its top days |
| Baltimore-Columbia-Towson, MD | 97.1 µg/m³ | 4.4 | Jun 29, 2023 | #3 of its top days |
| Washington-Arlington-Alexandria, DC-VA-MD-WV | 93.1 µg/m³ | 4.2 | Jun 29, 2023 | #4 of its top days |
| Scranton--Wilkes-Barre--Hazleton, PA | 92 µg/m³ | 10.7 | Jun 30, 2023 | #3 of its top days |
| Rochester, NY | 91.4 µg/m³ | 13.4 | Jun 30, 2023 | #2 of its top days |
| Philadelphia-Camden-Wilmington, PA-NJ-DE-MD | 90.5 µg/m³ | 7.1 | Jun 29, 2023 | #7 of its top days |
| Syracuse, NY | 87.9 µg/m³ | 7.6 | Jun 29, 2023 | #3 of its top days |
| Allentown-Bethlehem-Easton, PA-NJ | 79.9 µg/m³ | 7.1 | Jun 29, 2023 | #6 of its top days |
| St. Louis, MO-IL | 78.3 µg/m³ | 6.0 | Jun 28, 2023 | #2 of its top days |
| Minneapolis-St. Paul-Bloomington, MN-WI | 67.2 µg/m³ | 3.1 | Jun 28, 2023 | #13 of its top days |
| New York-Newark-Jersey City, NY-NJ-PA | 66.7 µg/m³ | 5.6 | Jun 30, 2023 | #7 of its top days |
| Richmond, VA | 66.3 µg/m³ | 4.8 | Jun 29, 2023 | #2 of its top days |
| Bridgeport-Stamford-Norwalk, CT | 60.2 µg/m³ | 4.9 | Jun 30, 2023 | #6 of its top days |
| Winston-Salem, NC | 60.2 µg/m³ | 2.7 | Jun 29, 2023 | #3 of its top days |
| Albany-Schenectady-Troy, NY | 54.8 µg/m³ | 4.9 | Jun 30, 2023 | #5 of its top days |
| New Haven-Milford, CT | 54.5 µg/m³ | 4.8 | Jun 30, 2023 | #9 of its top days |
| Worcester, MA-CT | 53.3 µg/m³ | 2.4 | Jul 1, 2023 | #4 of its top days |
| Knoxville, TN | 51.3 µg/m³ | 2.3 | Jun 29, 2023 | #22 of its top days |
| Springfield, MA | 50.6 µg/m³ | 2.3 | Jul 1, 2023 | #14 of its top days |
| Greensboro-High Point, NC | 47.7 µg/m³ | 2.2 | Jun 29, 2023 | #6 of its top days |
| Raleigh, NC | 47.4 µg/m³ | 3.9 | Jun 29, 2023 | #6 of its top days |
| Hartford-West Hartford-East Hartford, CT | 46.8 µg/m³ | 4.2 | Jun 30, 2023 | #12 of its top days |
| Virginia Beach-Norfolk-Newport News, VA-NC | 46.7 µg/m³ | 2.1 | Jun 29, 2023 | #16 of its top days |
| Chattanooga, TN-GA | 46.5 µg/m³ | 2.1 | Jun 29, 2023 | #16 of its top days |
| Providence-Warwick, RI-MA | 45.1 µg/m³ | 2.1 | Jul 1, 2023 | #11 of its top days |
| Charlotte-Concord-Gastonia, NC-SC | 44 µg/m³ | 2.0 | Jun 29, 2023 | #13 of its top days |
| Durham-Chapel Hill, NC | 43.8 µg/m³ | 3.7 | Jun 29, 2023 | #4 of its top days |
| Buffalo-Cheektowaga-Niagara Falls, NY | 40.9 µg/m³ | 1.9 | Jun 29, 2023 | #23 of its top days |
"Cigarettes, whole event" totals a metro's ranked event days at 22 µg/m³ per cigarette: what a person outdoors there breathed across the event, as the illustration. "All-time standing" is where this episode's days sit in each metro's ranked record (worst-area measure, since 1999). Full local context is on each metro's Air Records page.
The evidence
EPA AQS monitor qualifier 124
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 96 PM2.5 samples in the candidate CBSA on 2023-06-27, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 448 PM2.5 samples in the candidate CBSA on 2023-06-26, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier RF — Fire - Canadian. EPA AQS carries an agency-submitted request-exclusion qualifier (RF, Fire - Canadian.) on 96 PM2.5 samples in the candidate CBSA on 2023-06-27, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier RF — Fire - Canadian. EPA AQS carries an agency-submitted request-exclusion qualifier (RF, Fire - Canadian.) on 146 PM2.5 samples in the candidate CBSA on 2023-06-26, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier RF — Fire - Canadian. EPA AQS carries an agency-submitted request-exclusion qualifier (RF, Fire - Canadian.) on 96 PM2.5 samples in the candidate CBSA on 2023-06-28, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 82 PM2.5 samples in the candidate CBSA on 2023-06-26, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier RF — Fire - Canadian. EPA AQS carries an agency-submitted request-exclusion qualifier (RF, Fire - Canadian.) on 144 PM2.5 samples in the candidate CBSA on 2023-06-27, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier RF — Fire - Canadian. EPA AQS carries an agency-submitted request-exclusion qualifier (RF, Fire - Canadian.) on 147 PM2.5 samples in the candidate CBSA on 2023-06-29, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 96 PM2.5 samples in the candidate CBSA on 2023-06-27, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 96 PM2.5 samples in the candidate CBSA on 2023-06-29, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier RF — Fire - Canadian. EPA AQS carries an agency-submitted request-exclusion qualifier (RF, Fire - Canadian.) on 98 PM2.5 samples in the candidate CBSA on 2023-06-29, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 96 PM2.5 samples in the candidate CBSA on 2023-06-28, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- +112 more EPA AQS records on file
NWS Air Quality Alert 5
- Archived Chicago and Northwest Indiana Air Quality Alert, June 27, 2023 The Illinois/Northwest Indiana alerts explicitly identified wildfire smoke during the Chicago-area episode; ozone-only Wisconsin alerts were not retained. IEM is the archive, not the official system of record.
- Archived Indianapolis Air Quality Alert, June 27, 2023 The Indianapolis alert explicitly attributed particulates to Canadian wildfire smoke; Louisville-office Anderson matches were not retained. IEM is the archive, not the official system of record.
- Archived St. Louis Air Quality Alert, June 27, 2023 The St. Louis regional alert explicitly identified wildfire smoke during the particle-pollution event. IEM is the archive, not the official system of record.
- Archived Louisville Air Quality Alert, June 28, 2023 The Louisville alert explicitly identified wildfire smoke during the June 28 particle-pollution episode. IEM is the archive, not the official system of record.
- Archived New York State Air Quality Alert, June 29, 2023 New York State alerts explicitly attributed elevated fine-particle levels during the event to residual Canadian wildfire smoke. IEM is the archive, not the official system of record.
Agency and publisher pages 6
- Multi-Day Air Quality Advisory Issued Wisconsin DNR issued a multi-day advisory for Madison and Milwaukee-area conditions, explicitly attributing it to another round of smoke from Canadian wildfires.
- Technical Support Document for EPA’s Concurrence on PM2.5 Exceedances Measured During 2023 Wildfire Smoke Episodes Ohio EPA’s regulatory technical support documents wildfire complexes in Quebec and Ontario, smoke imagery, and transport analyses for the June 27–30 PM2.5 episode in Ohio.
- Governor Hochul Cautions New Yorkers as Air Quality Health Advisory Expanded to Include Entire State New York’s statewide advisory states that smoke from Canadian wildfires was causing unhealthy air quality across the state.
- Governor Hochul Announces Statewide Air Quality Health Advisory to Remain in Effect Through Friday New York’s statewide advisory says air quality remained impacted by Canadian wildfires and describes smoke-driven air pollution through June 30.
- IDPH Urges Illinoisans to Celebrate July 4th Safely, Offers Food Hygiene and Other Summer Safety Tips Illinois IDPH reported that unsafe Illinois air quality in the preceding days was due to smoke from Canadian wildfires.
- Live: One-third of US population under air quality alerts as East remains socked in by smoke Contemporaneous reporting states that Michigan’s statewide particulate-matter advisory was for smoke from Canadian wildfires.
News discovery (GDELT) 1
- Wildfire Smoke Pushing Back Into The Carolinas WCCB reported a Charlotte-area Code Orange alert extending into Thursday because of another push of wildfire smoke together with ground-level ozone.
What remains uncertain
- Agency-submitted AQS qualifiers are causal flags but do not by themselves establish EPA concurrence.
Status and provenance
Research preview: this record carries research-only status and its boundaries, cause, and name may change as evidence review completes. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula.