Wildfire smoke
Wildfire Smoke episode, 2017-09-05 through 2017-09-06
Daily PM2.5 peaked at 70.3 µg/m³ near Seattle across 2 covered metros home to 6.7 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 3.8 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 26 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 wildfire smoke as the broad cause for this time-bounded episode.
Sequence: Portland (Sep 5) → Seattle (Sep 6)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Seattle-Tacoma-Bellevue, WA | 70.3 µg/m³ | 3.2 | Sep 6, 2017 | #19 of its top days |
| Portland-Vancouver-Hillsboro, OR-WA | 70 µg/m³ | 6.1 | Sep 5, 2017 | #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 IT — Wildfire-U. S. EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 21 PM2.5 samples in the candidate CBSA on 2017-09-05, 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.
- AQS PM2.5 qualifier IT — Wildfire-U. S. EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 168 PM2.5 samples in the candidate CBSA on 2017-09-05, 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.
- AQS PM2.5 qualifier IT — Wildfire-U. S. EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2017-09-06, 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 144 PM2.5 samples in the candidate CBSA on 2017-09-06, 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.
NWS Air Quality Alert 1
- Air Quality Alert AQASEW An archived NWS Air Quality Alert for Seattle-Tacoma-Bellevue, WA, issued 2017-09-06T16:56Z, explicitly identifies wildfire smoke. IEM is the archive, not the official system of record.
Agency and publisher pages 2
- Portland Fire & Rescue Joins Mutual Aid Task Force Portland Fire & Rescue reported deployment to the Eagle Creek wildfire on September 5 and directed residents to wildfire-smoke health guidance, corroborating that the Portland portion of the event coincided with the active regional wildfire-smoke episode.
- Central WA wildfires shroud Seattle in ash, smoke Contemporaneous reporting described smoke and ash from central Washington wildfires over Seattle and a satellite image showing smoke across Washington, Oregon, and Idaho.
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.