Wildfire smoke
2020-10-04 Fresno wildfire-smoke episode
Daily PM2.5 peaked at 131.6 µg/m³ near Fresno across 1 covered metro home to 1.2 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 10.1 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
Supplied qualified evidence supports wildfire-smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Fresno, CA | 131.6 µg/m³ | 11.2 | Oct 5, 2020 | #13 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 4
- AQS PM2.5 qualifier RT — Wildfire-U. S. EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-10-04, 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 RT — Wildfire-U. S. EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-10-05, 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 IT — Wildfire-U. S. EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-10-04, identifying wildfire smoke 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 IT — Wildfire-U. S. EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 119 PM2.5 samples in the candidate CBSA on 2020-10-05, identifying wildfire smoke 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
- Community Air Monitoring Report (October 2020 - December 2020) District report identifies October 2020 PM2.5 spikes in South Central Fresno as wildfire-smoke impacts; it does not isolate the October 5 daily value.
What remains uncertain
- An AQS informational qualifier is an official submitting-agency flag, not an EPA-concurred exclusion determination.
- The supplied evidence resolves cause but does not establish identity with another candidate episode.
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.