Wildfire smoke Likely
Daily PM2.5 peaked at 47.4 µg/m³ near Charleston across 1 covered metro home to 869,940 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 ≈ 1.8 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 1.5 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
Charleston's airport reported smoke for seven hours during the PM2.5 event, and Charleston County's official hazard plan records a 28-acre wildland fire in the Awendaw Fire District on the exact date. Easterly surface flow makes that same-metro fire the best current source explanation, but no source explicitly apportions the daily PM2.5 mass to it.
Likely Applicable reporting or a supported inference makes this the best current causal explanation.
Charleston County Regional Hazard Mitigation Plan · Jan 1, 2005 hypothesis
Charleston County's official hazard mitigation plan records that a fire burned 28 acres in the Awendaw Fire District on March 8, 2002, citing the Charleston Post and Courier's March 9 report.
NOAA/NWS surface observations via Iowa Environmental Mesonet · Mar 8, 2002 hypothesis
Charleston, 9.4 km from the PM2.5 target monitor, reported the official present-weather code FU (smoke) during 7 observed hours inside the catalog event window.
Inference, not direct attribution
official_surface_smoke_plus_exact_window_source_occurrence.v1: This inference is recorded in the catalog methodology.
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
official_surface_smoke_plus_exact_window_source_occurrence.v1. This inference is recorded in the catalog methodology.
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 1 metro. The peak daily concentration is roughly 2.2 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 “Wildfire smoke” explanation; it does not assign the cause by itself.
Charleston-North Charleston, SC
Monitor comparison window 2002-03-05 to 2002-03-11 · PM2.5 target: FAA Tower
119% above nearby days
24% higher than surrounding days
50% higher than surrounding days
119% higher than surrounding days
50% higher than surrounding days
About the same as surrounding days
23% lower than surrounding days
67% lower than surrounding days
11% lower than surrounding days
24% 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 |
|---|---|---|---|---|
| Charleston-North Charleston, SC | 47.4 µg/m³ | 2.2 | Mar 8, 2002 | #8 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.
Charleston County Regional Hazard Mitigation Plan
Charleston County's official hazard mitigation plan records that a fire burned 28 acres in the Awendaw Fire District on March 8, 2002, citing the Charleston Post and Courier's March 9 report.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The plan records the fire occurrence but does not explicitly state that its smoke caused the Charleston PM2.5 measurement.
NOAA/NWS surface observations via Iowa Environmental Mesonet
Charleston, 9.4 km from the PM2.5 target monitor, reported the official present-weather code FU (smoke) during 7 observed hours inside the catalog event window.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The surface code establishes smoke at the nearby airport; it does not identify whether the source was a wildfire, prescribed burn, agricultural fire, or another local fire.
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.