Dust Likely
Daily PM2.5 peaked at 62.5 µg/m³ near El Paso across 1 covered metro home to 879,392 people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 2.4 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 2.1 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 nearby official airport record directly identifies five hours of blowing dust during the PM2.5 event. A strongly coarse-particle AQS fingerprint and the NWS high-wind, dry-westerly forecast independently fit that observed mechanism.
Likely Applicable reporting or a supported inference makes this the best current causal explanation.
NOAA/NWS surface observations via Iowa Environmental Mesonet · Apr 5, 2003 corroborates
EL PASO INTL ARPT, 12.8 km from the target PM2.5 monitor, reported blowing dust during 5 observed hours on the event date.
Inference, not direct attribution
event_autopsy_dust_triangulation_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
EL PASO INTL ARPT, 12.8 km from the target PM2.5 monitor, reported blowing dust during 5 observed hours on the event date.
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 1 metro. The peak daily concentration is roughly 2.8 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 “Dust” explanation; it does not assign the cause by itself.
El Paso, TX
Monitor comparison window 2003-04-02 to 2003-04-08 · PM2.5 target: El Paso UTEP
177% above nearby days
7% higher than surrounding days
360% higher than surrounding days
177% higher than surrounding days
360% higher than surrounding days
96% higher than surrounding days
42% higher than surrounding days
About the same as surrounding days
12% higher than surrounding days
24% lower than surrounding days
About the same as surrounding days
About the same as surrounding days
7% 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 |
|---|---|---|---|---|
| El Paso, TX | 62.5 µg/m³ | 2.8 | Apr 5, 2003 | #20 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
EL PASO INTL ARPT, 12.8 km from the target PM2.5 monitor, reported blowing dust during 5 observed hours on the event date.
A retained source supports the attributed cause for the stated place and dates.
The airport observation and regulatory PM2.5 monitor are nearby but not co-located.
National Weather Service El Paso via Iowa Environmental Mesonet
NWS El Paso forecast another windy day for April 5 as surface and upper-level gradients strengthened, mixing heights rose to roughly 600 mb, winds near that level approached 50 mph, and a dry westerly flow crossed the region.
Context for the event; this item does not establish the attributed cause by itself.
The forecast supplies the transport mechanism but does not itself state that blowing dust caused the PM2.5 observation.
U.S. EPA Air Quality System; IAQng event-autopsy calculation v1
The event-autopsy calculation from EPA AQS daily observations found median PM10 of 214 µg/m³ and PM2.5 of 28 µg/m³ on April 5, a fine-to-coarse proxy ratio of 0.13 consistent with a strongly coarse-particle episode.
Context for the event; this item does not establish the attributed cause by itself.
The ratio is descriptive and is not a formal source-apportionment result.
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.