Wildfire smoke
September 2005 central and eastern U.S. western-fire smoke episode
Daily PM2.5 peaked at 58.9 µg/m³ near Cincinnati across 7 covered metros home to 11 million people. 3 metros 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 ≈ 3.6 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 39 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 root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bo
Sequence: Memphis (Sep 9) → Little Rock (Sep 9) → Nashville (Sep 9) → Cincinnati (Sep 10) → Indianapolis (Sep 10) → Louisville/Jefferson County (Sep 11) → Dayton (Sep 13)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Cincinnati, OH-KY-IN | 58.9 µg/m³ | 5.0 | Sep 10, 2005 | #4 of its top days |
| Indianapolis-Carmel-Anderson, IN | 54 µg/m³ | 4.8 | Sep 10, 2005 | #15 of its top days |
| Memphis, TN-MS-AR | 49.7 µg/m³ | 4.3 | Sep 10, 2005 | #5 of its top days |
| Dayton, OH | 49.1 µg/m³ | 2.2 | Sep 13, 2005 | #11 of its top days |
| Louisville/Jefferson County, KY-IN | 48.9 µg/m³ | 4.4 | Sep 11, 2005 | #19 of its top days |
| Little Rock-North Little Rock-Conway, AR | 45 µg/m³ | 5.7 | Sep 11, 2005 | #5 of its top days |
| Nashville-Davidson--Murfreesboro--Franklin, TN | 41 µg/m³ | 5.7 | Sep 10, 2005 | #15 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 E — Forest Fire. EPA AQS carries an agency-submitted request-exclusion qualifier (E, Forest Fire.) on 3 PM2.5 samples in the candidate CBSA on 2005-09-10, 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 E — Forest Fire. EPA AQS carries an agency-submitted request-exclusion qualifier (E, Forest Fire.) on 2 PM2.5 samples in the candidate CBSA on 2005-09-10, 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 E — Forest Fire. EPA AQS carries an agency-submitted request-exclusion qualifier (E, Forest Fire.) on 2 PM2.5 samples in the candidate CBSA on 2005-09-13, 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.
Agency and publisher pages 4
- Extreme Aerosol Events Over Eastern North America: 1. Characterizing and Simulating Historical Events A retrospective scientific assessment identifies September 9–11, 2005 as a Midwest extreme aerosol event with elevated PM2.5 at many EPA sites. It supports grouping this event with the broader Midwest episode, while not assigning a city-specific source.
- Smoke Text Product — September 10, 2005 Satellite analysis observed thin smoke from the prior week's Idaho and Montana fires in the Mississippi, Ohio, and Tennessee river valleys, including northeast Arkansas, northern Mississippi, and western Tennessee. It supports wildfire-smoke transport over the Little Rock–Memphis event area, but describes smoke at mid-levels and does not establish its contribution to surface PM2.5.
- Smoke Text Product — September 9, 2005 Satellite analysis observed thin smoke from Idaho and Montana fires over most of Ohio, Indiana, and Kentucky during the event window. It supports wildfire-smoke transport across the Cincinnati–Indianapolis–Louisville area, but places the smoke in the middle to upper troposphere and does not establish a surface-PM2.5 contribution.
- Tennessee recommended nonattainment counties—EPA’s intended nonattainment counties EPA documented a widespread eastern-U.S. sulfate event on September 13, 2005, while rejecting the assessed wildfire-smoke claim in Chattanooga. It does not directly attribute PM2.5 in Cincinnati or Dayton.
What remains uncertain
- AQS qualifiers are submitting-agency causal flags and do not by themselves establish EPA concurrence.
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.