Wildfire smoke Agency determination
Daily PM2.5 peaked at 93.5 µg/m³ near Minneapolis across 6 covered metros home to 20 million people. 2 metros 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 ≈ 2.4 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 48 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.
Why we think this happened
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members.
Agency determination A government body issued a record naming this cause for this event: an NWS air-quality alert, a NOAA Storm Events record, or a state or local official archive.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jun 3, 2025 official
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 312 PM2.5 samples in the candidate CBSA on 2025-06-03, 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.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jun 5, 2025 official
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 76 PM2.5 samples in the candidate CBSA on 2025-06-05, 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.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jun 5, 2025 official
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 20 PM2.5 samples in the candidate CBSA on 2025-06-05, 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.
See every retained source and limitation ↓
Sequence: Minneapolis (Jun 3) → Milwaukee (Jun 4) → Madison (Jun 4) → Chicago (Jun 5) → Detroit (Jun 6) → Toledo (Jun 6)
Evidence path
A cause is more convincing when the record connects three things: something happened, the air mass moved toward the region, and local instruments responded. Here is how much of that chain is documented for this event.
Source or mechanism
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 312 PM2.5 samples in the candidate CBSA on 2025-06-03, identifying wildfire smoke as affecting the samples. An informational qualifier is an official…
View supporting source ↗Air-mass movement
Wisconsin DNR attributed the June 3–4 advisory to Canadian wildfire smoke moving northwest to southeast across Wisconsin.
View transport source ↗Local response
EPA monitors recorded the event across 6 metros. The peak daily concentration is roughly 4.3 cigarette-equivalents at the outdoor daily rate.
Inspect the pollutant and weather signals ↓Event autopsy
Before, during, and after the episode: nearby pollutant monitors and surface-weather stations show what changed. This context tests the “Wildfire smoke” explanation; it does not assign the cause by itself.
Minneapolis-St. Paul-Bloomington, MN-WI
Monitor comparison window 2025-05-31 to 2025-06-06 · PM2.5 target: Pacific Street
465% above nearby days
87% higher than surrounding days
135% higher than surrounding days
465% higher than surrounding days
135% higher than surrounding days
146% higher than surrounding days
24% lower than surrounding days
7% higher than surrounding days
38% lower than surrounding days
15% lower than surrounding days
87% higher than surrounding days
Madison, WI
Monitor comparison window 2025-06-01 to 2025-06-08 · PM2.5 target: MADISON - UNIVERSITY AVE WELL #6
65% above nearby days
15% lower than surrounding days
60% higher than surrounding days
65% higher than surrounding days
60% higher than surrounding days
16% lower than surrounding days
About the same as surrounding days
15% lower than surrounding days
Milwaukee-Waukesha-West Allis, WI
Monitor comparison window 2025-06-01 to 2025-06-08 · PM2.5 target: HARRINGTON BEACH PARK
85% above nearby days
26% lower than surrounding days
45% higher than surrounding days
85% higher than surrounding days
45% higher than surrounding days
115% higher than surrounding days
5% higher than surrounding days
86% lower than surrounding days
20% lower than surrounding days
About the same as surrounding days
About the same as surrounding days
26% lower than surrounding days
Chicago-Naperville-Elgin, IL-IN-WI
Monitor comparison window 2025-06-01 to 2025-06-08 · PM2.5 target: MAYFAIR PUMP STATION
56% above nearby days
About the same as surrounding days
38% higher than surrounding days
56% higher than surrounding days
38% higher than surrounding days
105% higher than surrounding days
About the same as surrounding days
12% lower than surrounding days
13% lower than surrounding days
21% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
Detroit-Warren-Dearborn, MI
Monitor comparison window 2025-06-03 to 2025-06-09 · PM2.5 target: TRINITY ST MARKS - Gordy Howe International Bridge (GHIB)
130% above nearby days
28% lower than surrounding days
58% higher than surrounding days
130% higher than surrounding days
58% higher than surrounding days
31% higher than surrounding days
30% higher than surrounding days
35% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
28% lower than surrounding days
Toledo, OH
Monitor comparison window 2025-06-03 to 2025-06-09 · PM2.5 target: Eastside Pump St
67% above nearby days
32% lower than surrounding days
56% higher than surrounding days
67% higher than surrounding days
56% higher than surrounding days
25% higher than surrounding days
24% lower than surrounding days
27% higher than surrounding days
About the same as surrounding days
32% lower than surrounding days
Source: U.S. EPA AirData daily observations and, where available, nearby ASOS/AWOS surface observations. Values are descriptive medians over the retained monitor set; missing measurements remain missing. Transport and source evidence remain separate layers because this instrument pattern does not assign a cause by itself.
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.
Views from the selected metro
Select a metro on the map to see nearby cameras. Where an operator archive reaches the event, drag the divider to compare two moments, adjust either date and time, or play the available event-day frames. Camera imagery is visual context, not an air-quality measurement or proof of smoke.
No useful public camera views are currently available within 80 km of this metro.
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Minneapolis-St. Paul-Bloomington, MN-WI | 93.5 µg/m³ | 4.3 | Jun 3, 2025 | #5 of its top days |
| Chicago-Naperville-Elgin, IL-IN-WI | 59.4 µg/m³ | 2.7 | Jun 5, 2025 | #21 of its top days |
| Detroit-Warren-Dearborn, MI | 56.3 µg/m³ | 2.6 | Jun 6, 2025 | #20 of its top days |
| Milwaukee-Waukesha-West Allis, WI | 51.2 µg/m³ | 2.3 | Jun 4, 2025 | #14 of its top days |
| Madison, WI | 49.8 µg/m³ | 2.3 | Jun 4, 2025 | #12 of its top days |
| Toledo, OH | 49.6 µg/m³ | 2.3 | Jun 6, 2025 | #10 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.
Public evidence library
Each card states what a source supports—and what it does not. Official records, research, reporting, community observations, and transparent inferences remain visibly different kinds of evidence.
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 2025-06-03, 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 76 PM2.5 samples in the candidate CBSA on 2025-06-05, 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 20 PM2.5 samples in the candidate CBSA on 2025-06-05, 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 452 PM2.5 samples in the candidate CBSA on 2025-06-05, 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 45 PM2.5 samples in the candidate CBSA on 2025-06-04, 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 2025-06-04, 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 429 PM2.5 samples in the candidate CBSA on 2025-06-04, 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 75 PM2.5 samples in the candidate CBSA on 2025-06-06, 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.
Southeast Michigan PM2.5 advisory due to wildfire smoke
Michigan EGLE continued a June 6 fine-particle advisory for southeast Michigan and explicitly attributed elevated PM2.5 to wildfire smoke; this directly covers the Detroit member. IEM is the archive, not the official system of record.
MPCA attributed the Twin Cities-area air-quality alert covering June 3 to wildfire smoke.
DNR Recommends Wisconsinites Limit Time Outside Due To Canadian Wildfire Smoke
Wisconsin DNR attributed the June 3–4 advisory to Canadian wildfire smoke moving northwest to southeast across Wisconsin.
Air quality advisory in effect for Southeast Michigan due to Canadian wildfire smoke
Local reporting relayed EGLE's advisory for elevated PM2.5 from Canadian wildfire smoke through June 6 in southeast Michigan, including the Detroit-area portion of this event.
Agency determination A government body issued a record naming this cause for this event: an NWS air-quality alert, a NOAA Storm Events record, or a state or local official archive.
This episode was grouped from the monitor record by the catalog pipeline and given its cause from the evidence listed above. It has not been individually reviewed and signed off, so its boundaries, cause, and name may change as evidence accumulates. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula. If it is wrong, tell us.