The Washington Post corroborates
In Hawaii, an ill wind blows in the vog
The May 11 report says exceptionally thick Kilauea vog had blown to Oahu and bathed Honolulu in light haze.
volcanic_emissions Possible
2008-05-15 Urban Honolulu, HI undefined episode
Daily PM2.5 peaked at 34.6 µg/m³ near Urban Honolulu across 1 covered metro home to 998,747 people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 1.4 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
The basis for “volcanic_emissions”
Contemporaneous reporting says unusually thick Kilauea vog had reached Oahu and bathed Honolulu in haze during the same week. The report is not tied to the individual monitor-day, so confidence remains possible.
Possible This is a transparent hypothesis supported by limited evidence or an explicit inference, not a definitive attribution.
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.
- 1Documented
Source or mechanism
volcanic_emissions
The May 11 report says exceptionally thick Kilauea vog had blown to Oahu and bathed Honolulu in light haze.
View supporting source ↗ - 2Research gap
Air-mass movement
The transport path has not been reconstructed
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.
- 3Documented
Local response
34.6 µg/m³ near Urban Honolulu
EPA monitors recorded the event across 1 metro. The peak daily concentration is roughly 1.6 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 “volcanic_emissions” explanation; it does not assign the cause by itself.
Urban Honolulu, HI
Monitor comparison window 2008-05-12 to 2008-05-18 · PM2.5 target: Kapolei
233% above nearby days
About the same as surrounding days
Pollution fingerprint
Metro-wide median of reporting monitors PM2.5 34.1 µg/m³
233% higher than surrounding days
Before10.3 µg/m³ Event34.1 µg/m³ After7.90 µg/m³
PM10 31 µg/m³
About the same as surrounding days
Before31 µg/m³ Event31 µg/m³ After31 µg/m³
Carbon monoxide 0.317 ppm
About the same as surrounding days
Before0.321 ppm Event0.317 ppm After0.312 ppm
Nitrogen dioxide 2.12 ppb
38% lower than surrounding days
Before3.86 ppb Event2.12 ppb After3.41 ppb
Sulfur dioxide 2.19 ppb
87% higher than surrounding days
Before1.05 ppb Event2.19 ppb After1.85 ppb
Ozone 0.009 ppm
About the same as surrounding days
Before0.017 ppm Event0.009 ppm After0.005 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.
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 |
|---|---|---|---|---|
| Urban Honolulu, HI | 34.6 µg/m³ | 1.6 | May 15, 2008 | #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.
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.
Volcano Watch: How voggy is it?
U.S. Geological Survey Hawaiian Volcano Observatory
USGS explains that the 2008 Halemaumau eruption increased volcanic gases and PM2.5 and documents the 2008 vog episode.
What it supports
Context for the event; this item does not establish the attributed cause by itself.
In Hawaii, an ill wind blows in the vog
The Washington Post
The May 11 report says exceptionally thick Kilauea vog had blown to Oahu and bathed Honolulu in light haze.
What it supports
A retained source supports the attributed cause for the stated place and dates.
What remains uncertain
- The retained evidence is scoped to the places and dates stated; it is not a catalog promotion.
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.