Other
California Central Valley Christmas–New Year 2000–2001 aerosol episode
Daily PM2.5 peaked at 112.7 µg/m³ near Bakersfield across 2 covered metros home to 2.9 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 8.2 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 24 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 modeling study specifically examines the Central Valley Christmas–New Year 2000–2001 episode, including December 31, and attributes the Bakersfield portion chiefly to secondary inorganic aerosol.
Sequence: Bakersfield (Dec 29) → San Jose (Dec 30)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Bakersfield, CA | 112.7 µg/m³ | 15.1 | Dec 31, 2000 | #11 of its top days |
| San Jose-Sunnyvale-Santa Clara, CA | 67.2 µg/m³ | 6.7 | Dec 30, 2000 | #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
- Simulating PM concentration during a winter episode in a subtropical valley: Sensitivity simulations and evaluation methods A modeling study examined the California Central Valley Christmas–New Year 2000–2001 episode, including December 31, and found elevated fine aerosol was principally secondary inorganic material, mainly ammonium nitrate, plus carbon. This supports attribution for the Bakersfield portion of this multi-place event; it does not assess San Jose.
What remains uncertain
- The evidence does not assess the concurrent San Jose portion or provide exact occurrence start and end dates.
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.