NASA Earth Observatory · Jun 30, 2003 hypothesis
Haze over the Atlantic Seaboard — June 26, 2003
NASA satellite observations show a broad haze plume over the eastern United States on June 26 and elevated carbon monoxide associated with that haze.
Wildfire smoke Possible
2003-06-26 to 2003-06-27 Durham-Chapel Hill, NC, Raleigh, NC, and 2 other metros wildfire-smoke episode
Daily PM2.5 peaked at 62.1 µg/m³ near Virginia Beach across 4 covered metros home to 5.3 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 ≈ 3.1 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 16 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.
Why we think this happened
The basis for “Wildfire smoke”
NASA observed a thick Atlantic-seaboard haze plume on June 24 that it said might contain Canadian wildfire smoke, then documented persistent haze with elevated carbon monoxide over the eastern United States on June 26. The temporal and regional match supports wildfire smoke only as a possible contributor, not a definitive attribution.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
See every retained source and limitation ↓
Sequence: Virginia Beach (Jun 26) → Raleigh (Jun 26) → Richmond (Jun 26) → Durham (Jun 26)
Evidence path
From source to city
A cause is more convincing when the record connects three things: something happened, the air mass moved toward the region, and local instruments responded. Here is how much of that chain is documented for this event.
- 1Open question
Source or mechanism
Source not directly documented
The catalog has a grouping hypothesis, but no retained source directly establishes the proposed cause.
- 2Documented
Air-mass movement
Transport into the affected region is documented
NASA satellite observations show a broad haze plume over the eastern United States on June 26 and elevated carbon monoxide associated with that haze.
View transport source ↗ - 3Documented
Local response
62.1 µg/m³ near Virginia Beach
EPA monitors recorded the event across 4 metros. The peak daily concentration is roughly 2.8 cigarette-equivalents at the outdoor daily rate.
Inspect the pollutant and weather signals ↓
Event autopsy
What the instruments saw
Before, during, and after the episode: nearby pollutant monitors and surface-weather stations show what changed. This context tests the “Wildfire smoke” explanation; it does not assign the cause by itself.
Durham-Chapel Hill, NC
Monitor comparison window 2003-06-23 to 2003-06-30
69% above nearby days
No adjacent-day comparison
Pollution fingerprint
Metro-wide median of reporting monitors PM2.5 40.5 µg/m³
69% higher than surrounding days
Before25.6 µg/m³ Event40.5 µg/m³ After17.5 µg/m³
PM10 53 µg/m³
No adjacent-day comparison
Before— Event53 µg/m³ After—
Carbon monoxide 0.420 ppm
5% higher than surrounding days
Before0.509 ppm Event0.420 ppm After0.361 ppm
Ozone 0.058 ppm
34% higher than surrounding days
Before0.046 ppm Event0.058 ppm After0.035 ppm
Raleigh, NC
Monitor comparison window 2003-06-23 to 2003-06-30 · PM2.5 target: Millbrook School
80% above nearby days
85% higher than surrounding days
Pollution fingerprint
Metro-wide median of reporting monitors PM2.5 43.8 µg/m³
80% higher than surrounding days
Before24.8 µg/m³ Event43.8 µg/m³ After19.6 µg/m³
PM10 63 µg/m³
85% higher than surrounding days
Before30 µg/m³ Event63 µg/m³ After30 µg/m³
Carbon monoxide 0.522 ppm
About the same as surrounding days
Before0.717 ppm Event0.522 ppm After—
Sulfur dioxide 5 ppb
30% higher than surrounding days
Before3.87 ppb Event5 ppb After2.35 ppb
Ozone 0.069 ppm
68% higher than surrounding days
Before0.041 ppm Event0.069 ppm After0.040 ppm
Atmospheric conditions
Nearby EPA weather observationsAbout the same as surrounding days
6% higher than surrounding days
Richmond, VA
Monitor comparison window 2003-06-23 to 2003-06-30
58% above nearby days
No adjacent-day comparison
Pollution fingerprint
Metro-wide median of reporting monitors PM2.5 39.6 µg/m³
58% higher than surrounding days
Before27.5 µg/m³ Event39.6 µg/m³ After22.8 µg/m³
PM10 58 µg/m³
No adjacent-day comparison
Before— Event58 µg/m³ After—
Carbon monoxide 0.301 ppm
About the same as surrounding days
Before0.274 ppm Event0.301 ppm After0.362 ppm
Nitrogen dioxide 9.85 ppb
About the same as surrounding days
Before13.2 ppb Event9.85 ppb After8.48 ppb
Sulfur dioxide 4.33 ppb
About the same as surrounding days
Before5.68 ppb Event4.33 ppb After3.42 ppb
Ozone 0.055 ppm
13% higher than surrounding days
Before0.050 ppm Event0.055 ppm After0.044 ppm
Atmospheric conditions
Nearby EPA weather observationsAbout the same as surrounding days
About the same as surrounding days
Virginia Beach-Norfolk-Newport News, VA-NC
Monitor comparison window 2003-06-23 to 2003-06-30 · PM2.5 target: DEQ Tidewater Regional Office
127% above nearby days
No adjacent-day comparison
Pollution fingerprint
Metro-wide median of reporting monitors PM2.5 53.5 µg/m³
127% higher than surrounding days
Before24.2 µg/m³ Event53.5 µg/m³ After19 µg/m³
PM10 71 µg/m³
No adjacent-day comparison
Before— Event71 µg/m³ After—
Carbon monoxide 0.200 ppm
20% lower than surrounding days
Before0.525 ppm Event0.200 ppm After0.242 ppm
Nitrogen dioxide 20.2 ppb
8% higher than surrounding days
Before27.8 ppb Event20.2 ppb After14.2 ppb
Sulfur dioxide 7.02 ppb
26% higher than surrounding days
Before5.70 ppb Event7.02 ppb After3.35 ppb
Ozone 0.072 ppm
47% higher than surrounding days
Before0.047 ppm Event0.072 ppm After0.048 ppm
Source: U.S. EPA AirData daily observations and, where available, nearby ASOS/AWOS surface observations. Values are descriptive medians over the retained monitor set; missing measurements remain missing. Transport and source evidence remain separate layers because this instrument pattern does not assign a cause by itself.
Air-mass reconstruction
Where the air had been
NOAA HYSPLIT traces the air arriving at each metro backward for 72 hours. Multiple arrival times and heights show whether the broad path is stable—or sensitive to assumptions about when and where the polluted layer arrived.
Air arriving near Durham-Chapel Hill
Peak-date arrivals · 2003-06-27
Broad history Mostly southwest of the metro
72-hour reach 200–750 km
Sensitivity runs 12 modeled paths
Near surface · 100 mLower atmosphere · 500 mHigher layer · 1,000 m
Each line begins 72 hours before arrival and points toward the metro. Color represents arrival height; repeated lines represent 00, 06, 12, and 18 UTC arrival assumptions. A path can show where the air traveled, but it cannot prove which source added the PM2.5.
Air arriving near Raleigh
Peak-date arrivals · 2003-06-27
Broad history Mostly southwest of the metro
72-hour reach 200–750 km
Sensitivity runs 12 modeled paths
Near surface · 100 mLower atmosphere · 500 mHigher layer · 1,000 m
Each line begins 72 hours before arrival and points toward the metro. Color represents arrival height; repeated lines represent 00, 06, 12, and 18 UTC arrival assumptions. A path can show where the air traveled, but it cannot prove which source added the PM2.5.
Air arriving near Richmond
Peak-date arrivals · 2003-06-26
Broad history Mostly northwest of the metro
72-hour reach 450–850 km
Sensitivity runs 12 modeled paths
Near surface · 100 mLower atmosphere · 500 mHigher layer · 1,000 m
Each line begins 72 hours before arrival and points toward the metro. Color represents arrival height; repeated lines represent 00, 06, 12, and 18 UTC arrival assumptions. A path can show where the air traveled, but it cannot prove which source added the PM2.5.
Air arriving near Virginia Beach-Norfolk-Newport News
Peak-date arrivals · 2003-06-26
Broad history Mostly northwest of the metro
72-hour reach 500–1,000 km
Sensitivity runs 12 modeled paths
Near surface · 100 mLower atmosphere · 500 mHigher layer · 1,000 m
Each line begins 72 hours before arrival and points toward the metro. Color represents arrival height; repeated lines represent 00, 06, 12, and 18 UTC arrival assumptions. A path can show where the air traveled, but it cannot prove which source added the PM2.5.
Measured daily PM2.5 at EPA monitors, as cigarette-equivalents
EPA monitors sit in metro areas, so the colour clusters there. Land between and beyond
them is unmeasured, not clean: this map shows where IAQng has readings, not the extent
of the smoke.
—
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.
Views from the selected metro
Camera views near
Select a metro on the map to see nearby cameras. Where an operator archive reaches the event, drag the divider to compare two moments, adjust either date and time, or play the available event-day frames. Camera imagery is visual context, not an air-quality measurement or proof of smoke.
No useful public camera views are currently available within 80 km of this metro.
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Virginia Beach-Norfolk-Newport News, VA-NC | 62.1 µg/m³ | 5.0 | Jun 26, 2003 | #7 of its top days |
| Raleigh, NC | 45.3 µg/m³ | 4.0 | Jun 27, 2003 | #8 of its top days |
| Richmond, VA | 44.4 µg/m³ | 2.0 | Jun 26, 2003 | #12 of its top days |
| Durham-Chapel Hill, NC | 41.3 µg/m³ | 3.7 | Jun 27, 2003 | #7 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.
Public evidence library
What supports this account
Each card states what a source supports—and what it does not. Official records, research, reporting, community observations, and transparent inferences remain visibly different kinds of evidence.
Haze over the Atlantic Seaboard — June 26, 2003
NASA Earth Observatory
NASA satellite observations show a broad haze plume over the eastern United States on June 26 and elevated carbon monoxide associated with that haze.
What it supports
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
Limit
The June 26 page confirms the plume and pollution but does not itself identify the aerosol source; the wildfire interpretation comes from NASA's qualified June 24 description of the same regional haze sequence.
Haze over the Atlantic Seaboard
NASA Earth Observatory
NASA observed thick East Coast haze on June 24 and said Canadian-fire smoke was a possibility.
What it supports
Context for the event; this item does not establish the attributed cause by itself.
Limit
The image precedes the supplied event and the attribution is qualified.
What remains uncertain
- NASA's wildfire language is explicitly qualified, so this remains a possible smoke contribution rather than a verified smoke attribution.
Status and provenance
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
This episode was grouped from the monitor record by the catalog pipeline and given its cause from the evidence listed above. It has not been individually reviewed and signed off, so its boundaries, cause, and name may change as evidence accumulates. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula. If it is wrong, tell us.