Wildfire smoke
2024-04-01 Austin-Round Rock, TX and San Antonio-New Braunfels, TX wildfire smoke episode
Daily PM2.5 peaked at 36.1 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 ≈ 1.2 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 6.3 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
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Sequence: San Antonio (Apr 1) → Austin (Apr 1)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| San Antonio-New Braunfels, TX | 36.1 µg/m³ | 1.6 | Apr 1, 2024 | #23 of its top days |
| Austin-Round Rock, TX | 34.2 µg/m³ | 1.6 | Apr 1, 2024 | #24 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 RG — Fire - Mexico/Central America. EPA AQS carries an agency-submitted request-exclusion qualifier (RG, Fire - Mexico/Central America.) on 24 PM2.5 samples in the candidate CBSA on 2024-04-01, identifying wildfire smoke 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 RG — Fire - Mexico/Central America. EPA AQS carries an agency-submitted request-exclusion qualifier (RG, Fire - Mexico/Central America.) on 24 PM2.5 samples in the candidate CBSA on 2024-04-01, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
What remains uncertain
- Agency-submitted AQS qualifiers support attribution but do not by themselves 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.