Mixed causes Possible
Daily PM2.5 peaked at 61.9 µg/m³ near Scranton across 1 covered metro home to 574,009 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 ≈ 2.4 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 1.4 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
NASA confirmed carbon-monoxide-associated haze over the eastern United States on June 26, Pennsylvania recorded same-day ozone exceedances, and the exact-date NWS discussion described widespread local haze and fog. Scranton simultaneously recorded a sharp multi-monitor PM2.5 rise. Together these support a regional mixed-pollution episode at possible confidence without identifying a unique emissions source.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
National Weather Service Binghamton via Iowa Environmental Mesonet · Jun 26, 2003 hypothesis
The exact-date NWS discussion expected the Scranton forecast area to remain warm and humid with widespread haze and fog before a cold front cleared the region.
Pennsylvania Department of Environmental Protection hypothesis
Pennsylvania's annual report lists one-hour ozone exceedances at Reading and Lancaster on June 26, corroborating a regional photochemical-pollution episode in eastern Pennsylvania.
NASA Earth Observatory · Jun 30, 2003 hypothesis
NASA's MOPITT observations on June 26 confirmed high carbon monoxide associated with a broad pall of haze over the eastern United States.
Inference, not direct attribution
documented_regional_combustion_haze_overlap_possible.v1: This inference is recorded in the catalog methodology.
Evidence path
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.
Source or mechanism
documented_regional_combustion_haze_overlap_possible.v1. This inference is recorded in the catalog methodology.
Air-mass movement
NASA's MOPITT observations on June 26 confirmed high carbon monoxide associated with a broad pall of haze over the eastern United States.
View transport source ↗Local response
EPA monitors recorded the event across 1 metro. The peak daily concentration is roughly 2.8 cigarette-equivalents at the outdoor daily rate.
Inspect the pollutant and weather signals ↓Event autopsy
Before, during, and after the episode: nearby pollutant monitors and surface-weather stations show what changed. This context tests the “Mixed causes” explanation; it does not assign the cause by itself.
Scranton--Wilkes-Barre--Hazleton, PA
Monitor comparison window 2003-06-23 to 2003-06-29 · PM2.5 target: Wilkes-Barre
106% above nearby days
7 calm hours observed
Haze reported during 16 hours
106% higher than surrounding days
84% higher than surrounding days
36% higher than surrounding days
39% higher than surrounding days
161% higher than surrounding days
42% higher than surrounding days
7 kt maximum · 7 of 24 observed hours calm
8 observed hours at or below 3 miles
65°F to 90°F
100% maximum
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.
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
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.
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Scranton--Wilkes-Barre--Hazleton, PA | 61.9 µg/m³ | 2.8 | Jun 26, 2003 | #8 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
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.
NASA Earth Observatory
NASA's MOPITT observations on June 26 confirmed high carbon monoxide associated with a broad pall of haze over the eastern United States.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The observation confirms a broad combustion-pollution haze but does not uniquely distinguish wildfire smoke from anthropogenic combustion or apportion local PM2.5.
National Weather Service Binghamton via Iowa Environmental Mesonet
The exact-date NWS discussion expected the Scranton forecast area to remain warm and humid with widespread haze and fog before a cold front cleared the region.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The forecast confirms the local haze chronology but does not identify its emissions sources.
Pennsylvania Department of Environmental Protection
Pennsylvania's annual report lists one-hour ozone exceedances at Reading and Lancaster on June 26, corroborating a regional photochemical-pollution episode in eastern Pennsylvania.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The listed ozone monitors are outside Scranton, and ozone does not determine Scranton PM2.5 composition.
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.