Wildfire smoke
July 12–13, 2025 Upper Midwest Canadian wildfire-smoke episode
Daily PM2.5 peaked at 89.8 µg/m³ near Minneapolis across 2 covered metros home to 5.3 million people. 1 metro placed a top-ten day in their record.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 4.6 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 25 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.
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
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members.
Sequence: Minneapolis (Jul 12) → Milwaukee (Jul 13)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Minneapolis-St. Paul-Bloomington, MN-WI | 89.8 µg/m³ | 6.7 | Jul 12, 2025 | #6 of its top days |
| Milwaukee-Waukesha-West Allis, WI | 49.1 µg/m³ | 2.2 | Jul 13, 2025 | #21 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 3
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 312 PM2.5 samples in the candidate CBSA on 2025-07-13, 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 312 PM2.5 samples in the candidate CBSA on 2025-07-12, 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 83 PM2.5 samples in the candidate CBSA on 2025-07-13, 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.
NWS Air Quality Alert 1
- Wisconsin air-quality alert for Canadian wildfire smoke Wisconsin's alert said Canadian wildfire smoke would affect surface air quality statewide through the weekend, directly covering Milwaukee on July 13. IEM is the archive, not the official system of record.
Agency and publisher pages 3
- Air quality alert issued due to wildfire smoke until Monday, July 14, for all of Minnesota MPCA attributed the statewide alert, including the Twin Cities metro area, to heavy ground-level smoke from wildfires in central Canada.
- Another Major Smoke Event, July 11-13, 2025 Minnesota DNR described dense smoke from wildfires in southern Canada over Minnesota during July 11–13.
- Unhealthy smoke from Canadian wildfires blankets the Upper Midwest when people want to be outside Associated Press reported unhealthy air from drifting Canadian wildfire smoke across Minnesota and parts of Wisconsin during this regional July 12–13 episode.
What remains uncertain
- The supplied evidence does not identify or quantify every specific source contributing across all proposed members.
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.