Stagnant pollution mixture Possible
Daily PM2.5 peaked at 61.3 µg/m³ near Columbus across 3 covered metros home to 3.7 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 ≈ 2.5 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 9.3 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
SCAMP's full episode analysis identifies January 11-15, 2001 as a regional-scale Ohio Valley PM2.5 episode under locally low wind speeds and sustained surface stagnation. The catalog event falls inside that exact window. The evidence supports an accumulation mechanism, not a unique emissions source.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
PubMed / Journal of the Air & Waste Management Association · May 1, 2005 corroborates
The full SCAMP case study identifies January 11-15, 2001 as a regional-scale PM2.5 episode and reports locally low winds and sustained surface stagnation until a frontal passage cleared the episode.
Journal of the Air & Waste Management Association · May 1, 2005 corroborates
SCAMP documented an Ohio regional PM2.5 episode from late 11 January through early 15 January 2001, associated with locally low wind speeds and ending with an occluded front. It corroborates regional timing but does not attribute pollution at Akron, Columbus, or Dayton to a specific source.
Inference, not direct attribution
exact_window_regional_field_study_stagnation_possible.v1: This inference is recorded in the catalog methodology.
See every retained source and limitation ↓
Sequence: Akron (Jan 12) → Columbus (Jan 13) → Dayton (Jan 13)
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
The full SCAMP case study identifies January 11-15, 2001 as a regional-scale PM2.5 episode and reports locally low winds and sustained surface stagnation until a frontal passage cleared the episode.
View supporting source ↗Air-mass movement
The retained record does not yet show how air traveled from the proposed source to these metros. A trajectory replay or dated plume analysis belongs here.
Local response
EPA monitors recorded the event across 3 metros. The peak daily concentration is roughly 2.8 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 “Stagnant pollution mixture” explanation; it does not assign the cause by itself.
Akron, OH
Monitor comparison window 2001-01-09 to 2001-01-16 · PM2.5 target: East HS
93% above nearby days
59% higher than surrounding days
93% higher than surrounding days
59% higher than surrounding days
66% higher than surrounding days
41% higher than surrounding days
Columbus, OH
Monitor comparison window 2001-01-09 to 2001-01-16 · PM2.5 target: Fairgrounds Garage
137% above nearby days
128% higher than surrounding days
137% higher than surrounding days
128% higher than surrounding days
101% higher than surrounding days
About the same as surrounding days
Dayton, OH
Monitor comparison window 2001-01-09 to 2001-01-16
72% above nearby days
No adjacent-day comparison
72% higher than surrounding days
No adjacent-day comparison
59% higher than surrounding days
31% higher 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 |
|---|---|---|---|---|
| Columbus, OH | 61.3 µg/m³ | 2.8 | Jan 13, 2001 | #6 of its top days |
| Dayton, OH | 59 µg/m³ | 2.7 | Jan 13, 2001 | #4 of its top days |
| Akron, OH | 47.5 µg/m³ | 4.3 | Jan 13, 2001 | #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.
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.
PubMed / Journal of the Air & Waste Management Association
The full SCAMP case study identifies January 11-15, 2001 as a regional-scale PM2.5 episode and reports locally low winds and sustained surface stagnation until a frontal passage cleared the episode.
A retained source supports the attributed cause for the stated place and dates.
The intensive monitor was in Steubenville; applying the regional-scale finding to Akron, Columbus, and Dayton is capped at possible.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
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.