Mixed causes Possible
Daily PM2.5 peaked at 84.9 µg/m³ near Pittsburgh across 3 covered metros home to 4.3 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 ≈ 4.0 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 17 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
Exact-window NOAA evidence supports a mixture of transported fire smoke and haze, while EPA regional analysis points to substantial sulfate and cautions against a wildfire-only attribution.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
NOAA Office of Satellite and Product Operations · Sep 13, 2005 corroborates
NOAA describes broad smoke and haze extending along the Appalachians into the eastern Great Lakes, with contributions from western wildfires and lower-Mississippi agricultural or controlled burning.
See every retained source and limitation ↓
Sequence: Pittsburgh (Sep 13) → Akron (Sep 13) → Buffalo (Sep 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
NOAA describes broad smoke and haze extending along the Appalachians into the eastern Great Lakes, with contributions from western wildfires and lower-Mississippi agricultural or controlled burning.
View supporting source ↗Air-mass movement
NOAA describes broad smoke and haze extending along the Appalachians into the eastern Great Lakes, with contributions from western wildfires and lower-Mississippi agricultural or controlled burning.
View transport source ↗Local response
EPA monitors recorded the event across 3 metros. The peak daily concentration is roughly 3.9 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 “Mixed causes” explanation; it does not assign the cause by itself.
Akron, OH
Monitor comparison window 2005-09-10 to 2005-09-17 · PM2.5 target: East HS
225% above nearby days
13% higher than surrounding days
225% higher than surrounding days
13% higher than surrounding days
78% higher than surrounding days
31% higher than surrounding days
Buffalo-Cheektowaga-Niagara Falls, NY
Monitor comparison window 2005-09-10 to 2005-09-17 · PM2.5 target: BUFFALO
335% above nearby days
24% higher than surrounding days
21% higher than surrounding days
335% higher than surrounding days
21% higher than surrounding days
46% higher than surrounding days
239% higher than surrounding days
78% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
7% higher than surrounding days
24% higher than surrounding days
Pittsburgh, PA
Monitor comparison window 2005-09-10 to 2005-09-17 · PM2.5 target: Liberty
55% above nearby days
61% higher than surrounding days
55% higher than surrounding days
61% higher than surrounding days
71% higher than surrounding days
20% higher than surrounding days
90% higher than surrounding days
13% 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 |
|---|---|---|---|---|
| Pittsburgh, PA | 84.9 µg/m³ | 7.1 | Sep 13, 2005 | #8 of its top days |
| Akron, OH | 52.1 µg/m³ | 2.4 | Sep 13, 2005 | #11 of its top days |
| Buffalo-Cheektowaga-Niagara Falls, NY | 47 µg/m³ | 2.1 | Sep 13, 2005 | #11 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.
NOAA Office of Satellite and Product Operations
NOAA describes broad smoke and haze extending along the Appalachians into the eastern Great Lakes, with contributions from western wildfires and lower-Mississippi agricultural or controlled burning.
A retained source supports the attributed cause for the stated place and dates.
The product does not prove that all satellite-observed smoke reached the surface at each metro.
U.S. EPA
EPA's regional record describes high PM2.5 and sulfate around September 8-13 and says the available documentation did not establish wildfire causation.
Context for the event; this item does not establish the attributed cause by itself.
The assessment is regional and does not individually resolve Akron, Buffalo, or Pittsburgh.
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.