Stagnant pollution mixture Likely
Daily PM2.5 peaked at 45.2 µg/m³ near Augusta across 3 covered metros home to 2.4 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 ≈ 2.0 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 4.9 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
NASA's exact-date satellite narrative describes hot, humid, stagnant air and widespread haze from Pennsylvania to Georgia, including EPA particle warnings across the Southeast. It identifies high pressure trapping accumulating emissions from vehicles, power plants, and fires as the episode mechanism.
Likely Applicable reporting or a supported inference makes this the best current causal explanation.
NASA Earth Observatory · Jul 28, 2005 official
NASA's July 26 imagery and narrative document hot, humid, stagnant air, particle warnings across the Southeast, and haze along the coast from Pennsylvania to Georgia. The assessment identifies high pressure trapping accumulating emissions from vehicles, power plants, and fires.
See every retained source and limitation ↓
Sequence: Columbia (Jul 26) → Augusta (Jul 27) → Charleston (Jul 27)
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
NASA's July 26 imagery and narrative document hot, humid, stagnant air, particle warnings across the Southeast, and haze along the coast from Pennsylvania to Georgia. The assessment identifies high pressure trapping accumulating emissions from…
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 2.1 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.
Columbia, SC
Monitor comparison window 2005-07-23 to 2005-07-30 · PM2.5 target: BATES HOUSE
43% above nearby days
9% higher than surrounding days
34% higher than surrounding days
43% higher than surrounding days
34% higher than surrounding days
34% higher than surrounding days
20% higher than surrounding days
61% higher than surrounding days
36% higher than surrounding days
9% higher than surrounding days
Augusta-Richmond County, GA-SC
Monitor comparison window 2005-07-23 to 2005-07-30 · PM2.5 target: Augusta
27% above nearby days
No adjacent-day comparison
27% higher than surrounding days
No adjacent-day comparison
9% higher than surrounding days
21% higher than surrounding days
Charleston-North Charleston, SC
Monitor comparison window 2005-07-23 to 2005-07-30 · PM2.5 target: CHARLESTON PUBLIC WORKS
56% above nearby days
17% higher than surrounding days
37% higher than surrounding days
56% higher than surrounding days
37% higher than surrounding days
11% higher than surrounding days
About the same as surrounding days
7% higher than surrounding days
13% higher than surrounding days
17% 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 |
|---|---|---|---|---|
| Augusta-Richmond County, GA-SC | 45.2 µg/m³ | 2.1 | Jul 27, 2005 | #11 of its top days |
| Columbia, SC | 43 µg/m³ | 3.8 | Jul 26, 2005 | #9 of its top days |
| Charleston-North Charleston, SC | 41.8 µg/m³ | 1.9 | Jul 27, 2005 | #15 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.
NASA Earth Observatory
NASA's July 26 imagery and narrative document hot, humid, stagnant air, particle warnings across the Southeast, and haze along the coast from Pennsylvania to Georgia. The assessment identifies high pressure trapping accumulating emissions from vehicles, power plants, and fires.
An official source supports the attributed cause for the stated place and dates.
The assessment describes a mixed regional episode and does not apportion the daily PM2.5 among the listed emissions categories.
Likely Applicable reporting or a supported inference makes this the best current causal explanation.
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.