Wildfire smoke
Wildfire-smoke episode, 2018-08-20 through 2018-08-22
Daily PM2.5 peaked at 105.3 µg/m³ near Seattle across 1 covered metro home to 4.1 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 ≈ 12.8 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 53 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.
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Seattle-Tacoma-Bellevue, WA | 105.3 µg/m³ | 14.0 | Aug 21, 2018 | #10 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 3
- AQS PM2.5 qualifier IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 216 PM2.5 samples in the candidate CBSA on 2018-08-22, 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 IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 215 PM2.5 samples in the candidate CBSA on 2018-08-21, 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 IF — Fire - Canadian. EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 204 PM2.5 samples in the candidate CBSA on 2018-08-20, 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 2018-08-21T09:56Z, explicitly identifies wildfire smoke. IEM is the archive, not the official system of record.
Agency and publisher pages 2
- EPA Issues Air Quality Advisory for Tribal Reservations in Western Washington EPA issued a western-Washington air-quality advisory for stagnant conditions and smoke from large wildfires in the Washington Cascades and British Columbia through August 22.
- 2018 Washington Wildfire Smoke Symposium Report The report documents wildfire smoke blanketing Seattle on August 20, 2018.
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.