Wildfire smoke
July 2004 eastern U.S. Alaskan wildfire-smoke episode
Daily PM2.5 peaked at 56.4 µg/m³ near New York across 10 covered metros home to 34 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 1.9 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 65 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: Durham (Jul 21) → New York (Jul 22) → Allentown (Jul 22) → Scranton (Jul 22) → Charlotte (Jul 22) → Columbia (Jul 22) → Boston (Jul 23) → Springfield (Jul 23) → Jacksonville (Jul 23) → Worcester (Jul 23)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| New York-Newark-Jersey City, NY-NJ-PA | 56.4 µg/m³ | 2.6 | Jul 22, 2004 | #15 of its top days |
| Allentown-Bethlehem-Easton, PA-NJ | 54.5 µg/m³ | 2.5 | Jul 22, 2004 | #24 of its top days |
| Scranton--Wilkes-Barre--Hazleton, PA | 47.2 µg/m³ | 2.1 | Jul 22, 2004 | #21 of its top days |
| Boston-Cambridge-Newton, MA-NH | 46.4 µg/m³ | 2.1 | Jul 23, 2004 | #18 of its top days |
| Springfield, MA | 44.7 µg/m³ | 2.0 | Jul 23, 2004 | #24 of its top days |
| Charlotte-Concord-Gastonia, NC-SC | 43.9 µg/m³ | 2.0 | Jul 22, 2004 | #14 of its top days |
| Jacksonville, FL | 40.4 µg/m³ | 3.6 | Jul 23, 2004 | #17 of its top days |
| Worcester, MA-CT | 39.9 µg/m³ | 1.8 | Jul 23, 2004 | #17 of its top days |
| Columbia, SC | 37.6 µg/m³ | 1.7 | Jul 22, 2004 | #22 of its top days |
| Durham-Chapel Hill, NC | 37.5 µg/m³ | 1.7 | Jul 21, 2004 | #16 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 E — Forest Fire. EPA AQS carries an agency-submitted request-exclusion qualifier (E, Forest Fire.) on 1 PM2.5 sample in the candidate CBSA on 2004-07-22, identifying wildfire smoke as affecting the sample. 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 2004-07-21, 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 1 PM2.5 sample in the candidate CBSA on 2004-07-21, identifying wildfire smoke as affecting the sample. 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 2004-07-22, 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 3
- Estimating the impact of the 2004 Alaskan forest fires on episodic particulate matter pollution over the eastern United States through assimilation of satellite-derived aerosol optical depths in a regional air quality model Analysis of measured and modeled PM2.5 attributed a 24–42% median enhancement across the eastern United States during 19–23 July 2004 to transported particulate pollution from Alaskan forest fires; Jacksonville's event falls on the final day of that assessed period.
- Smoke from Alaska Fires off U.S. East Coast NASA reported widespread intense Alaskan-fire smoke crossing North America and being swept over the East Coast on 21 July 2004, corroborating the regional transport context shortly before the event.
- Slide 1 A NASA workshop analysis identifies a July 18–22 PM2.5 AQI episode, a plume from Alaskan forest fires, and merger of smoke and sulfate plumes over the Eastern Seaboard on July 22. It supports regional smoke transport as a hypothesis, but does not quantify or specifically attribute the listed metro-area observations.
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.