Wildfire smoke
2021-07-29 Minneapolis-St. Paul-Bloomington wildfire-smoke episode
Daily PM2.5 peaked at 115.6 µg/m³ near Minneapolis across 1 covered metro home to 3.8 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 ≈ 10.2 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 38 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
Supplied qualified evidence supports wildfire-smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Minneapolis-St. Paul-Bloomington, MN-WI | 115.6 µg/m³ | 11.5 | Jul 29, 2021 | #3 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 168 PM2.5 samples in the candidate CBSA on 2021-07-30, 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 168 PM2.5 samples in the candidate CBSA on 2021-07-29, 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 IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 168 PM2.5 samples in the candidate CBSA on 2021-07-31, 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
- Air Quality Alert AQAMPX An archived NWS Air Quality Alert for Minneapolis-St. Paul-Bloomington, MN-WI, issued 2021-07-29T14:37Z, explicitly identifies wildfire smoke. IEM is the archive, not the official system of record.
Agency and publisher pages 1
- Summer of smoke, 2021 Minnesota DNR documents thick ground smoke in St. Paul on July 29, 2021 and identifies fine particulate matter from the smoke as creating health hazards.
What remains uncertain
- An AQS informational qualifier is an official submitting-agency flag, not an EPA-concurred exclusion determination.
- The supplied evidence resolves cause but does not establish identity with another candidate episode.
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.