Wildfire smoke Agency determination
Named source Hughes Fire 10,425 acres , CA · IRWIN 2025-CAANF-250270
Daily PM2.5 peaked at 45.3 µg/m³ near Oxnard across 1 covered metro home to 835,427 people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 1.6 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 1.3 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 supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Agency determination A government body issued a record naming this cause for this event: an NWS air-quality alert, a NOAA Storm Events record, or a state or local official archive.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jan 22, 2025 official
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 30 PM2.5 samples in the candidate CBSA on 2025-01-22, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
Ventura County Air Pollution Control District via NWS · Jan 22, 2025 official
Ventura County APCD explicitly attributed increased particulate matter in Oxnard and nearby communities to wildfire smoke. IEM is the archive, not the official system of record.
Ventura County Air Pollution Control District · Jan 22, 2025 official
The district stated that smoke from the Hughes Fire made the AQI unhealthy in Oxnard and other Ventura County communities and identified PM2.5 as the relevant fine-particle pollutant.
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
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 30 PM2.5 samples in the candidate CBSA on 2025-01-22, identifying wildfire smoke as affecting the samples. An informational qualifier is an official…
View supporting source ↗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
State labor officials reported wildfire smoke affecting Oxnard and directed employers to monitor PM2.5 AQI.
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 “Wildfire smoke” explanation; it does not assign the cause by itself.
Oxnard-Thousand Oaks-Ventura, CA
Monitor comparison window 2025-01-19 to 2025-01-25 · PM2.5 target: El Rio-Rio Mesa School #2
119% above nearby days
About the same as surrounding days
286% higher than surrounding days
119% higher than surrounding days
286% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
65% lower than surrounding days
13% higher than surrounding days
About the same as surrounding days
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 |
|---|---|---|---|---|
| Oxnard-Thousand Oaks-Ventura, CA | 45.3 µg/m³ | 2.1 | Jan 22, 2025 | #11 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 30 PM2.5 samples in the candidate CBSA on 2025-01-22, identifying wildfire smoke as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
Archived Ventura County Air Quality Alert, January 22, 2025
Ventura County APCD explicitly attributed increased particulate matter in Oxnard and nearby communities to wildfire smoke. IEM is the archive, not the official system of record.
Air Quality Alert for smoke issued in county
The district stated that smoke from the Hughes Fire made the AQI unhealthy in Oxnard and other Ventura County communities and identified PM2.5 as the relevant fine-particle pollutant.
State labor officials reported wildfire smoke affecting Oxnard and directed employers to monitor PM2.5 AQI.
Cited authorities: Ventura County Air Pollution Control District
Agency determination A government body issued a record naming this cause for this event: an NWS air-quality alert, a NOAA Storm Events record, or a state or local official archive.
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.