Other
San Joaquin Valley particulate-ammonium-nitrate episode
Daily PM2.5 peaked at 154.7 µg/m³ near Bakersfield across 2 covered metros home to 1.8 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 ≈ 6.7 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 12 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
CRPAQS explicitly identifies one major San Joaquin Valley episode during 4–7 January 2001, driven by particulate ammonium nitrate, and places both dates within it. CRPAQS explicitly identifies one major San Joaquin Valley episode during 4–7 January 2001, driven by particulate ammonium nitrate, and places both dates within it.
Sequence: Bakersfield (Jan 5) → Oxnard (Jan 7)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Bakersfield, CA | 154.7 µg/m³ | 12.5 | Jan 5, 2001 | #2 of its top days |
| Oxnard-Thousand Oaks-Ventura, CA | 45.1 µg/m³ | 2.1 | Jan 7, 2001 | #12 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
Agency and publisher pages 1
- PM2.5 chemical composition and spatiotemporal variability during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) CRPAQS identifies a major San Joaquin Valley PM2.5 episode during 4–7 January 2001 driven by particulate ammonium nitrate; on 5 January its plume blanketed the broad region between Bakersfield and Fresno.
What remains uncertain
- The evidence directly describes Bakersfield and regional transport; it does not separately apportion the Oxnard observation in the January 7 candidate.
- The evidence directly describes Bakersfield and regional transport; it does not separately apportion the Oxnard observation in this candidate.
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.