Dust
Dust episode, 2018-06-30 through 2018-07-01
Daily PM2.5 peaked at 49.7 µg/m³ near Dallas across 2 covered metros home to 11 million 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 ≈ 3.1 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 34 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 frozen evidence supports dust as the broad cause for this time-bounded episode.
Sequence: Dallas (Jun 30) → Austin (Jun 30)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Dallas-Fort Worth-Arlington, TX | 49.7 µg/m³ | 4.3 | Jul 1, 2018 | #8 of its top days |
| Austin-Round Rock, TX | 36.6 µg/m³ | 3.3 | Jul 1, 2018 | #16 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 IA — African Dust. EPA AQS carries an agency-submitted informational qualifier (IA, African Dust.) on 7 PM2.5 samples in the candidate CBSA on 2018-07-01, identifying windblown or transported dust as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier IA — African Dust. EPA AQS carries an agency-submitted informational qualifier (IA, African Dust.) on 2 PM2.5 samples in the candidate CBSA on 2018-07-01, identifying windblown or transported dust as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
Agency and publisher pages 1
- Dust from Africa brought hazy skies to Dallas-Fort Worth this weekend Contemporaneous reporting, citing the Texas Commission on Environmental Quality forecast, says Saharan dust was affecting Texas and could reach Dallas–Fort Worth and Austin.
What remains uncertain
- AQS qualifiers are submitting-agency causal flags and do not by themselves establish EPA concurrence.
- The evidence resolves the broad cause but does not require a named fire, facility, or incident.
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.