Stagnant pollution mixture Possible
Daily PM2.5 peaked at 46.8 µg/m³ near Buffalo across 1 covered metro home to 1.2 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 1.8 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 2.0 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
Buffalo's four-monitor PM2.5 rise coincided with 12 observed haze hours and compatible carbon-monoxide, nitrogen-dioxide, and sulfur-dioxide increases. The exact-date NWS discussion independently documented a hot, hazy, ridge-capped air mass. Together these support broad stagnant mixed-pollution accumulation at possible confidence without identifying source-sector shares.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
National Weather Service Buffalo via Iowa Environmental Mesonet · Jun 25, 2002 hypothesis
On the event day, NWS Buffalo described hot and hazy conditions across the forecast area, a milky sky, upper ridging, and an inversion near 10,000 feet that suppressed convection.
U.S. EPA AirData hypothesis
EPA records show median daily PM2.5 of 41.85 micrograms per cubic meter across 4 monitors, 2.029 times the adjacent-window level. Compatible co-pollutant rises were carbon monoxide (1.256x), nitrogen dioxide (1.512x), sulfur dioxide (1.58x).
National Weather Service surface observations via Iowa Environmental Mesonet · Jun 25, 2002 hypothesis
BUFFALO INTL ARPT recorded calm conditions during 17% of event hours and wind at or below three knots during 29%. Observations included 12 haze hours, 7 mist hours, minimum visibility 4 miles.
Inference, not direct attribution
exact_nws_hazy_ridge_pollution_fingerprint_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
exact_nws_hazy_ridge_pollution_fingerprint_possible.v1. This inference is recorded in the catalog methodology.
Air-mass movement
The retained record does not yet show how air traveled from the proposed source to these metros. A trajectory replay or dated plume analysis belongs here.
Local response
EPA monitors recorded the event across 1 metro. The peak daily concentration is roughly 2.1 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 “Stagnant pollution mixture” explanation; it does not assign the cause by itself.
Buffalo-Cheektowaga-Niagara Falls, NY
Monitor comparison window 2002-06-22 to 2002-06-28 · PM2.5 target: BUFFALO
42% above nearby days
4 calm hours observed
Haze reported during 12 hours
42% higher than surrounding days
No adjacent-day comparison
19% higher than surrounding days
30% higher than surrounding days
37% higher than surrounding days
82% higher than surrounding days
12 kt maximum · 4 of 24 observed hours calm
0 observed hours at or below 3 miles
66°F to 85°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 |
|---|---|---|---|---|
| Buffalo-Cheektowaga-Niagara Falls, NY | 46.8 µg/m³ | 2.1 | Jun 25, 2002 | #13 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.
National Weather Service Buffalo via Iowa Environmental Mesonet
On the event day, NWS Buffalo described hot and hazy conditions across the forecast area, a milky sky, upper ridging, and an inversion near 10,000 feet that suppressed convection.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The documented inversion was near 10,000 feet and is evidence of a capped air mass, not direct proof of a shallow surface inversion.
National Weather Service surface observations via Iowa Environmental Mesonet
BUFFALO INTL ARPT recorded calm conditions during 17% of event hours and wind at or below three knots during 29%. Observations included 12 haze hours, 7 mist hours, minimum visibility 4 miles.
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
A single surface station documents ventilation and obscuration but not the full vertical profile or particle source mix.
U.S. EPA AirData
EPA records show median daily PM2.5 of 41.85 micrograms per cubic meter across 4 monitors, 2.029 times the adjacent-window level. Compatible co-pollutant rises were carbon monoxide (1.256x), nitrogen dioxide (1.512x), sulfur dioxide (1.58x).
This source supports a possible mechanism or occurrence; it does not establish the cause by itself.
The pollution fingerprint does not uniquely apportion traffic, heating, industry, wood combustion, dust, or secondary aerosol.
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.