2024-10-15 Little Rock-North Little Rock-Conway, AR dust episode
October 15, 2024
Daily PM2.5 peaked at 43.3 µg/m³ near Little Rock across
1 covered metro home to 769,258 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 ≈ 1.5 cigarettes.
Across everyone living in the affected metros, that is the collective equivalent of
≈ 1.1 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
The basis for “Dust”
The official exact-day account documents wind-blown agricultural dust and haze in the same regional weather regime, but not a monitor-specific causal finding.
PossibleThis is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
NWS reports strong northeasterly winds on October 15, with gusts of 30-40 mph, and hazy skies where dirt was blown from harvested farm fields in eastern Arkansas.
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.
NWS reports strong northeasterly winds on October 15, with gusts of 30-40 mph, and hazy skies where dirt was blown from harvested farm fields in eastern Arkansas.
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.
Research gap
3
Local response
43.3 µg/m³ near Little Rock
EPA monitors recorded the event across 1 metro.
The peak daily concentration is roughly 2.0 cigarette-equivalents at the outdoor daily rate.
Before, during, and after the episode: nearby pollutant monitors and surface-weather
stations show what changed. This context tests the “Dust” explanation; it does
not assign the cause by itself.
Observed context · not attribution
Little Rock-North Little Rock-Conway, AR
Monitor comparison window 2024-10-12 to 2024-10-18 · PM2.5 target: PARR
5 pollutant signals
Fine-particle pulse42.5 µg/m³
57% above nearby days
Air movement4.25 kt
31% higher than surrounding days
PM1020 µg/m³
33% lower than surrounding days
Pollution fingerprint
Metro-wide median of reporting monitors
PM2.542.5 µg/m³
57% higher than surrounding days
Before22.6 µg/m³ Event42.5 µg/m³ After27.1 µg/m³
PM1020 µg/m³
33% lower than surrounding days
Before30 µg/m³ Event20 µg/m³ After31 µg/m³
Carbon monoxide0.362 ppm
About the same as surrounding days
Before0.346 ppm Event0.362 ppm After0.450 ppm
Sulfur dioxide0.525 ppb
24% higher than surrounding days
Before0.425 ppb Event0.525 ppb After0.392 ppb
Ozone0.032 ppm
About the same as surrounding days
Before0.045 ppm Event0.032 ppm After0.030 ppm
Atmospheric conditions
Nearby EPA weather observations
Humidity25.3 %
About the same as surrounding days
Temperature59.5 °F
About the same as surrounding days
Wind4.25 kt
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.
Measured daily PM2.5 at EPA monitors, as cigarette-equivalents
EPA monitors sit in metro areas, so the colour clusters there. Land between and beyond
them is unmeasured, not clean: this map shows where IAQng has readings, not the extent
of the smoke.
—
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.
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.
"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
What supports this account
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.
1 retained source
Official record
October 2024 weather summary for Arkansas
National Weather Service Little Rock
NWS reports strong northeasterly winds on October 15, with gusts of 30-40 mph, and hazy skies where dirt was blown from harvested farm fields in eastern Arkansas.
What it supports
An official source supports the attributed cause for the stated place and dates.
Limit
The narrative is statewide and emphasizes eastern Arkansas rather than directly tying Little Rock's monitor to dust.
What remains uncertain
Geographic scope is regional, so the proposal is capped at possible.
Status and provenance
PossibleThis 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.