Wildfire smoke
2025-09-04 wildfire smoke episode affecting Spokane-Spokane Valley, WA
Daily PM2.5 peaked at 168.1 µg/m³ near Spokane across 1 covered metro home to 604,962 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 ≈ 17.5 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 11 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 supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Spokane-Spokane Valley, WA | 168.1 µg/m³ | 18.5 | Sep 6, 2025 | #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
Official records
- NOAA Storm Events Dust Storm, ARIZONA, Sep 3, 2025 "Scattered to numerous thunderstorms developed over the northern half of AZ as well as near the International Border during the afternoon hours with more isolated activity developing across the foothills and higher terrai…" record →
- NOAA Storm Events Dust Storm, ARIZONA, Sep 4, 2025 "An upper-level trough moving through the area providing strong upper-level ascent combined with MLCAPE values between 1500-3000 J/kg and PWAT values between 1.8-2.0 (associated with the remnants of Tropical Cyclone Loren…" record →
- NOAA Storm Events Dust Storm, ARIZONA, Sep 4, 2025 "An upper-level trough moving through the area providing strong upper-level ascent combined with MLCAPE values between 1500-3000 J/kg and PWAT values between 1.8-2.0 (associated with the remnants of Tropical Cyclone Loren…" record →
Agency and publisher pages 2
- Wildfire smoke affecting local air quality The Spokane Regional Clean Air Agency, through the regional health district notice, attributed worsening Spokane air quality to smoke from regional wildfires combined with poor overnight ventilation.
- Unhealthy air quality to persist over the weekend with ongoing wildfires across the region A National Weather Service meteorologist said smoke and haze would persist in Spokane; the report identified fires in Stevens and Ferry counties, British Columbia, and northwest Montana as the principal regional smoke sources.
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.