Dust
2024-07-31 dust episode affecting Austin-Round Rock, TX, San Antonio-New Braunfels, TX
Daily PM2.5 peaked at 38.7 µg/m³ near San Antonio across 2 covered metros home to 5.3 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 1.3 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 7.0 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.
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.
What happened, in the record
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Sequence: San Antonio (Jul 31) → Austin (Jul 31)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| San Antonio-New Braunfels, TX | 38.7 µg/m³ | 1.8 | Jul 31, 2024 | #18 of its top days |
| Austin-Round Rock, TX | 37.4 µg/m³ | 1.7 | Jul 31, 2024 | #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.
The evidence
EPA AQS monitor qualifier 2
- AQS PM2.5 qualifier RA — African Dust. EPA AQS carries an agency-submitted request-exclusion qualifier (RA, African Dust.) on 24 PM2.5 samples in the candidate CBSA on 2024-07-31, identifying windblown or transported dust as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier RA — African Dust. EPA AQS carries an agency-submitted request-exclusion qualifier (RA, African Dust.) on 24 PM2.5 samples in the candidate CBSA on 2024-07-31, identifying windblown or transported dust as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
Agency and publisher pages 1
- Exceptional event demonstration: PM2.5 summary for Harrison, Kleberg, and Travis Counties, 2022-2024 TCEQ identifies Saharan Desert dust as the July 31 exceptional-event source at Travis County monitors, supporting the Austin portion of this event; it does not assess San Antonio.
What remains uncertain
- Agency-submitted AQS qualifiers do not establish EPA concurrence.
Status and provenance
Research preview: this record carries research-only status and its boundaries, cause, and name may change as evidence review completes. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula.