Daily PM2.5 peaked at 127.3 µg/m³ near El Paso across
1 covered metro home to 879,392 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 ≈ 5.4 cigarettes.
Across everyone living in the affected metros, that is the collective equivalent of
≈ 4.7 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”
Exact-date local reporting directly connects the observed dust storm with poor air quality.
LikelyApplicable reporting or a supported inference makes this the best current causal explanation.
The local chief meteorologist reported a dust storm in El Paso on March 6, visibility below one mile, poor air quality, wind gusts near 50 mph, and dust and sand persisting into the evening.
NOAA/NCEI Storm Events Database · Mar 6, 2025corroborates
NOAA's Storm Events record documents a March 6 El Paso County dust storm with quarter-mile or lower visibility. It corroborates the dust episode but does not quantify its PM2.5 contribution.
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.
The local chief meteorologist reported a dust storm in El Paso on March 6, visibility below one mile, poor air quality, wind gusts near 50 mph, and dust and sand persisting into the evening.
NOAA's Storm Events record documents a March 6 El Paso County dust storm with quarter-mile or lower visibility. It corroborates the dust episode but does not quantify its PM2.5 contribution.
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
El Paso, TX
Monitor comparison window 2025-03-03 to 2025-03-09 · PM2.5 target: Ascarate Park SE
6 pollutant signals
Fine-particle pulse122 µg/m³
173% above nearby days
Air movement6.67 kt
14% lower than surrounding days
PM10529 µg/m³
18% higher than surrounding days
Pollution fingerprint
Metro-wide median of reporting monitors
PM2.5122 µg/m³
173% higher than surrounding days
Before44.8 µg/m³ Event122 µg/m³ After7.85 µg/m³
PM10529 µg/m³
18% higher than surrounding days
Before448 µg/m³ Event529 µg/m³ After60 µg/m³
Carbon monoxide0.396 ppm
27% higher than surrounding days
Before0.311 ppm Event0.396 ppm After0.275 ppm
Nitrogen dioxide18.2 ppb
41% higher than surrounding days
Before12.9 ppb Event18.2 ppb After6.21 ppb
Sulfur dioxide0.656 ppb
190% higher than surrounding days
Before0.191 ppb Event0.656 ppb After0.226 ppb
Ozone0.034 ppm
About the same as surrounding days
Before0.036 ppm Event0.034 ppm After0.030 ppm
Atmospheric conditions
Nearby EPA weather observations
Humidity18.4 %
41% lower than surrounding days
Pressure888 Millibars
About the same as surrounding days
Temperature62.4 °F
10% higher than surrounding days
Wind6.67 kt
14% lower 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
Where the air had been
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.
Transport context · not source attribution
Air arriving near El Paso
Peak-date arrivals · 2025-03-06
Broad historyMostly northwest of the metro
72-hour reach800–2,750 km
Sensitivity runs12 modeled paths
Near surface · 100 mLower atmosphere · 500 mHigher layer · 1,000 m
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.
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
News report
Terrible Thursday; more gusty winds Friday with some dust
KVIA ABC-7 El Paso
The local chief meteorologist reported a dust storm in El Paso on March 6, visibility below one mile, poor air quality, wind gusts near 50 mph, and dust and sand persisting into the evening.
What it supports
A retained source supports the attributed cause for the stated place and dates.
What remains uncertain
The report does not provide a formal source-apportionment percentage for the daily PM2.5 value.
Status and provenance
LikelyApplicable 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.