Mixed causes Likely
Daily PM2.5 peaked at 72.3 µg/m³ near Dallas across 2 covered metros home to 11 million people. 1 metro recorded their worst day on record.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 3.7 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 40 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 regional event spans two related but not identical impacts: official and contemporaneous reporting documents the March 14 dust outbreak in North Texas, while Austin's exact window contains both officially observed blowing dust and an official local advisory attributing incoming smoke to the Crabapple Fire. The mixed label preserves both causes rather than forcing one source across both metros.
Likely Applicable reporting or a supported inference makes this the best current causal explanation.
Village of The Hills, Texas · Mar 15, 2025 official
The mayor of The Hills, in the Austin metro, warned that a large smoke column was moving into the area from the west and attributed the general smoke to the 400-plus-acre Crabapple Fire north of Fredericksburg.
National Weather Service Austin/San Antonio · Apr 1, 2025 corroborates
The official Austin-Bergstrom monthly climate report states that blowing dust was observed on March 15, inside the Austin event window.
NBC 5 Dallas-Fort Worth corroborates
Contemporaneous reporting describes the March 14 dust storm and dust moving into North Texas.
Inference, not direct attribution
exact_dust_plus_direct_fire_smoke_mixed_likely.v1: This inference is recorded in the catalog methodology.
See every retained source and limitation ↓
Sequence: Dallas (Mar 14) → Austin (Mar 15)
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
The mayor of The Hills, in the Austin metro, warned that a large smoke column was moving into the area from the west and attributed the general smoke to the 400-plus-acre Crabapple Fire north of Fredericksburg.
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 2 metros. The peak daily concentration is roughly 3.3 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.
Dallas-Fort Worth-Arlington, TX
Monitor comparison window 2025-03-11 to 2025-03-18 · PM2.5 target: Denton Airport South
590% above nearby days
12% higher than surrounding days
No adjacent-day comparison
590% higher than surrounding days
No adjacent-day comparison
6% lower than surrounding days
52% lower than surrounding days
About the same as surrounding days
6% lower than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
12% higher than surrounding days
Austin-Round Rock, TX
Monitor comparison window 2025-03-11 to 2025-03-18 · PM2.5 target: Austin Webberville Rd
179% above nearby days
14% higher than surrounding days
366% higher than surrounding days
179% higher than surrounding days
366% higher than surrounding days
29% lower than surrounding days
57% lower than surrounding days
166% higher than surrounding days
About the same as surrounding days
6% higher than surrounding days
14% 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 |
|---|---|---|---|---|
| Dallas-Fort Worth-Arlington, TX | 72.3 µg/m³ | 5.4 | Mar 14, 2025 | Worst day on record |
| Austin-Round Rock, TX | 38.9 µg/m³ | 1.8 | Mar 15, 2025 | #12 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.
National Weather Service Austin/San Antonio
The official Austin-Bergstrom monthly climate report states that blowing dust was observed on March 15, inside the Austin event window.
A retained source supports the attributed cause for the stated place and dates.
The monthly report documents the occurrence of blowing dust but does not apportion the Austin PM2.5 measurement between dust and smoke.
Village of The Hills, Texas
The mayor of The Hills, in the Austin metro, warned that a large smoke column was moving into the area from the west and attributed the general smoke to the 400-plus-acre Crabapple Fire north of Fredericksburg.
An official source supports the attributed cause for the stated place and dates.
The advisory establishes the fire-smoke plume in the Austin metro but does not quantify its share of the daily PM2.5 measurement.
U.S. EPA Air Quality System; IAQng event-autopsy calculation v1
EPA observations show Austin event-window PM2.5 near 20.6 µg/m³ versus 7.8 before and 5.3 after. PM10 reached a 144.5 µg/m³ median versus 31 before, while sulfur dioxide rose to roughly three times its preceding level. The combined fingerprint is consistent with the independently documented dust-and-smoke mixture.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The pollutants were not necessarily measured at the same sites, and the descriptive fingerprint is not a formal source-apportionment result.
National Weather Service Amarillo
NWS documents the major March 14, 2025 Panhandle dust storm.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
NBC 5 Dallas-Fort Worth
Contemporaneous reporting describes the March 14 dust storm and dust moving into North Texas.
A retained source supports the attributed cause for the stated place and dates.
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.