Prescribed fire Likely
Daily PM2.5 peaked at 40.5 µg/m³ near Little Rock across 1 covered metro home to 769,258 people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 2.6 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 2.0 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
Little Rock's airport reported smoke during the two-day PM2.5 event. NOAA satellite analysts documented a large concentration of fires across central and eastern Arkansas and a regional smoke area during the exact window, identifying most fires as agricultural or prescribed burns.
Likely Applicable reporting or a supported inference makes this the best current causal explanation.
NOAA/NESDIS Satellite Services Division · Oct 28, 2005 hypothesis
NOAA satellite analysts reported a very large cluster of fires across southeastern Missouri, eastern and central Arkansas, and northwestern Mississippi producing a moderate regional smoke area. They identified most of the fires as agricultural or prescribed burns.
NOAA/NESDIS Satellite Services Division · Oct 29, 2005 hypothesis
NOAA's next satellite narrative again reported a large number of fires in the Lower and Middle Mississippi Valley and smoke moving west or northwest across most of that region during the catalog window.
NOAA/NWS surface observations via Iowa Environmental Mesonet · Oct 30, 2005 hypothesis
LITTLE ROCK/ADAMS, 10.9 km from the PM2.5 target monitor, reported the official present-weather code FU (smoke) during 1 observed hour 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
NOAA satellite analysts reported a very large cluster of fires across southeastern Missouri, eastern and central Arkansas, and northwestern Mississippi producing a moderate regional smoke area. They identified most of the fires as agricultural or…
View transport source ↗Local response
EPA monitors recorded the event across 1 metro. The peak daily concentration is roughly 1.8 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 “Prescribed fire” explanation; it does not assign the cause by itself.
Little Rock-North Little Rock-Conway, AR
Monitor comparison window 2005-10-26 to 2005-11-02 · PM2.5 target: ADEQ
60% above nearby days
About the same as surrounding days
60% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
74% higher than surrounding days
45% 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.
Air-mass reconstruction
NOAA HYSPLIT traces the air arriving at each metro backward for 72 hours. Multiple arrival times and heights show whether the broad path is stable—or sensitive to assumptions about when and where the polluted layer arrived.
Air arriving near Little Rock-North Little Rock-Conway
Peak-date arrivals · 2005-10-29
Each line begins 72 hours before arrival and points toward the metro. Color represents arrival height; repeated lines represent 00, 06, 12, and 18 UTC arrival assumptions. A path can show where the air traveled, but it cannot prove which source added the PM2.5.
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 |
|---|---|---|---|---|
| Little Rock-North Little Rock-Conway, AR | 40.5 µg/m³ | 3.7 | Oct 29, 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.
NOAA/NWS surface observations via Iowa Environmental Mesonet
LITTLE ROCK/ADAMS, 10.9 km from the PM2.5 target monitor, reported the official present-weather code FU (smoke) during 1 observed hour 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.
NOAA/NESDIS Satellite Services Division
NOAA's next satellite narrative again reported a large number of fires in the Lower and Middle Mississippi Valley and smoke moving west or northwest across most of that region during the catalog window.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The narrative does not isolate Little Rock or distinguish the contribution of individual burns.
NOAA/NESDIS Satellite Services Division
NOAA satellite analysts reported a very large cluster of fires across southeastern Missouri, eastern and central Arkansas, and northwestern Mississippi producing a moderate regional smoke area. They identified most of the fires as agricultural or prescribed burns.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The narrative describes the regional smoke field and burn type but does not identify one fire as the source of Little Rock's PM2.5.
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.