Other
June 27, 2005 Great Lakes regional PM episode
Daily PM2.5 peaked at 79.2 µg/m³ near Detroit across 6 covered metros home to 11 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 ≈ 2.3 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
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episo
Sequence: Detroit (Jun 27) → Cleveland (Jun 27) → Toledo (Jun 27) → Milwaukee (Jun 27) → Akron (Jun 27) → Grand Rapids (Jun 27)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Detroit-Warren-Dearborn, MI | 79.2 µg/m³ | 3.6 | Jun 27, 2005 | #8 of its top days |
| Cleveland-Elyria, OH | 54.9 µg/m³ | 2.5 | Jun 27, 2005 | #21 of its top days |
| Toledo, OH | 53.4 µg/m³ | 2.4 | Jun 27, 2005 | #6 of its top days |
| Milwaukee-Waukesha-West Allis, WI | 49.5 µg/m³ | 2.3 | Jun 27, 2005 | #18 of its top days |
| Akron, OH | 48.7 µg/m³ | 2.2 | Jun 27, 2005 | #16 of its top days |
| Grand Rapids-Wyoming, MI | 47.9 µg/m³ | 2.2 | Jun 27, 2005 | #19 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
Agency and publisher pages 1
- Extreme Aerosol Events Over Eastern North America: 1. Characterizing and Simulating Historical Events This retrospective scientific assessment identifies June 26–28, 2005 as a Midwest extreme aerosol event, with elevated PM2.5 at many EPA sites; its assessed regional-scale extreme events are described as dominated by anthropogenic emissions. It supports a regional anthropogenic-aerosol attribution, not a city-specific source apportionment.
What remains uncertain
- The retained evidence does not map the documented mechanism to a more specific catalog cause type.
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.