Other
January 31–February 6, 2005 Midwest stagnation and nitrate episode
Daily PM2.5 peaked at 81.6 µg/m³ near Detroit across 14 covered metros home to 34 million people. 7 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 ≈ 5.1 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 176 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: Des Moines (Jan 30) → Kansas City (Jan 30) → Minneapolis (Jan 31) → Indianapolis (Jan 31) → Cincinnati (Jan 31) → Columbus (Jan 31) → Omaha (Jan 31) → Dayton (Jan 31) → St. Louis (Feb 2) → Detroit (Feb 3) → +4 more metros
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Detroit-Warren-Dearborn, MI | 81.6 µg/m³ | 16.2 | Feb 5, 2005 | #7 of its top days |
| Grand Rapids-Wyoming, MI | 75.3 µg/m³ | 13.4 | Feb 4, 2005 | #6 of its top days |
| Minneapolis-St. Paul-Bloomington, MN-WI | 69.9 µg/m³ | 3.2 | Jan 31, 2005 | #11 of its top days |
| Indianapolis-Carmel-Anderson, IN | 63.2 µg/m³ | 2.9 | Jan 31, 2005 | #8 of its top days |
| Chicago-Naperville-Elgin, IL-IN-WI | 62.6 µg/m³ | 8.3 | Feb 3, 2005 | #16 of its top days |
| Cincinnati, OH-KY-IN | 56.3 µg/m³ | 2.6 | Jan 31, 2005 | #8 of its top days |
| Columbus, OH | 51.8 µg/m³ | 2.4 | Jan 31, 2005 | #15 of its top days |
| Omaha-Council Bluffs, NE-IA | 51.7 µg/m³ | 2.4 | Jan 31, 2005 | #7 of its top days |
| Dayton, OH | 50 µg/m³ | 2.3 | Jan 31, 2005 | #9 of its top days |
| Des Moines-West Des Moines, IA | 48.8 µg/m³ | 8.3 | Jan 31, 2005 | #9 of its top days |
| St. Louis, MO-IL | 48.3 µg/m³ | 2.2 | Feb 2, 2005 | #22 of its top days |
| Toledo, OH | 48.3 µg/m³ | 4.3 | Feb 6, 2005 | #13 of its top days |
| Madison, WI | 43.5 µg/m³ | 2.0 | Feb 3, 2005 | #21 of its top days |
| Kansas City, MO-KS | 39 µg/m³ | 1.8 | Jan 30, 2005 | #24 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
- PM2.5 and PM10-2.5 Compositions during Wintertime Episodes of Elevated PM Concentrations across the Midwestern USA Scientific assessment identifies a January 31–February 6, 2005 Midwest episode driven by meteorological stagnation and nitrate; it explicitly covers Iowa and Missouri, supporting the Des Moines and Kansas City portion of this multi-place event, but not an attribution for Omaha.
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.