Wildfire smoke Agency determination
Daily PM2.5 peaked at 199.3 µg/m³ near Fresno across 8 covered metros home to 28 million people. 1 metro recorded their worst day on record; 8 placed a top-ten day.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 13.8 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 389 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
Supplied qualified evidence supports wildfire-smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event 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 · Sep 10, 2020 official
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 95 PM2.5 samples in the candidate CBSA on 2020-09-10, 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.
U.S. EPA Air Quality System and the submitting air monitoring agency · Sep 11, 2020 official
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-11, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
U.S. EPA Air Quality System and the submitting air monitoring agency · Sep 11, 2020 official
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-11, 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.
See every retained source and limitation ↓
Sequence: San Francisco (Sep 10) → Sacramento (Sep 11) → Stockton (Sep 11) → San Jose (Sep 11) → Fresno (Sep 12) → Los Angeles (Sep 12) → San Diego (Sep 13) → Oxnard (Sep 13)
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 95 PM2.5 samples in the candidate CBSA on 2020-09-10, identifying wildfire smoke as affecting the samples. An informational qualifier is an official…
View supporting source ↗Air-mass movement
NOAA HYSPLIT modeled 96 backward paths across multiple arrival times and heights. They show where the air traveled, not which source polluted it.
Explore the modeled paths ↓Local response
EPA monitors recorded the event across 8 metros. The peak daily concentration is roughly 9.1 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 “Wildfire smoke” explanation; it does not assign the cause by itself.
San Francisco-Oakland-Hayward, CA
Monitor comparison window 2020-09-07 to 2020-09-20 · PM2.5 target: Oakland
324% above nearby days
81% higher than surrounding days
324% higher than surrounding days
81% higher than surrounding days
105% higher than surrounding days
7% lower than surrounding days
About the same as surrounding days
9% lower than surrounding days
Sacramento--Roseville--Arden-Arcade, CA
Monitor comparison window 2020-09-07 to 2020-09-20 · PM2.5 target: Colfax-City Hall
70% above nearby days
7% lower than surrounding days
21% higher than surrounding days
70% higher than surrounding days
21% higher than surrounding days
63% higher than surrounding days
10% higher than surrounding days
About the same as surrounding days
11% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
7% lower than surrounding days
San Jose-Sunnyvale-Santa Clara, CA
Monitor comparison window 2020-09-07 to 2020-09-20 · PM2.5 target: San Jose - Knox Avenue
127% above nearby days
About the same as surrounding days
44% higher than surrounding days
127% higher than surrounding days
44% higher than surrounding days
85% higher than surrounding days
15% lower than surrounding days
About the same as surrounding days
12% lower than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
Stockton-Lodi, CA
Monitor comparison window 2020-09-07 to 2020-09-20 · PM2.5 target: Manteca
135% above nearby days
7% lower than surrounding days
32% higher than surrounding days
135% higher than surrounding days
32% higher than surrounding days
92% higher than surrounding days
9% higher than surrounding days
9% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
7% lower than surrounding days
Fresno, CA
Monitor comparison window 2020-09-07 to 2020-09-20 · PM2.5 target: Table Mountain Air Monitoring Site
30% above nearby days
9% lower than surrounding days
About the same as surrounding days
30% higher than surrounding days
About the same as surrounding days
44% higher than surrounding days
16% higher than surrounding days
6% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
9% lower than surrounding days
Los Angeles-Long Beach-Anaheim, CA
Monitor comparison window 2020-09-09 to 2020-09-20 · PM2.5 target: Lebec
65% above nearby days
About the same as surrounding days
23% higher than surrounding days
65% higher than surrounding days
23% higher than surrounding days
19% higher than surrounding days
6% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
8% lower than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
Oxnard-Thousand Oaks-Ventura, CA
Monitor comparison window 2020-09-09 to 2020-09-20 · PM2.5 target: El Rio-Rio Mesa School #2
78% above nearby days
6% lower than surrounding days
35% higher than surrounding days
78% higher than surrounding days
35% higher than surrounding days
About the same as surrounding days
8% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
6% lower than surrounding days
San Diego-Carlsbad, CA
Monitor comparison window 2020-09-09 to 2020-09-20 · PM2.5 target: Pala Airpad
148% above nearby days
About the same as surrounding days
About the same as surrounding days
148% higher than surrounding days
About the same as surrounding days
22% higher than surrounding days
About the same as surrounding days
23% higher than surrounding days
18% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as 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.
Air-mass reconstruction
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 Fresno
Peak-date arrivals · 2020-09-16
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 Sacramento--Roseville--Arden-Arcade
Peak-date arrivals · 2020-09-11
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 San Francisco-Oakland-Hayward
Peak-date arrivals · 2020-09-11
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 San Jose-Sunnyvale-Santa Clara
Peak-date arrivals · 2020-09-11
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 Stockton-Lodi
Peak-date arrivals · 2020-09-11
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 Los Angeles-Long Beach-Anaheim
Peak-date arrivals · 2020-09-12
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 Oxnard-Thousand Oaks-Ventura
Peak-date arrivals · 2020-09-15
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 San Diego-Carlsbad
Peak-date arrivals · 2020-09-14
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.
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 |
|---|---|---|---|---|
| Fresno, CA | 199.3 µg/m³ | 45.8 | Sep 16, 2020 | Worst day on record |
| San Francisco-Oakland-Hayward, CA | 167.7 µg/m³ | 29.1 | Sep 11, 2020 | #2 of its top days |
| Sacramento--Roseville--Arden-Arcade, CA | 147.3 µg/m³ | 23.5 | Sep 11, 2020 | #6 of its top days |
| Stockton-Lodi, CA | 140 µg/m³ | 22.2 | Sep 11, 2020 | #4 of its top days |
| San Jose-Sunnyvale-Santa Clara, CA | 123.1 µg/m³ | 20.2 | Sep 11, 2020 | #3 of its top days |
| Los Angeles-Long Beach-Anaheim, CA | 102.7 µg/m³ | 4.7 | Sep 12, 2020 | #7 of its top days |
| San Diego-Carlsbad, CA | 96.7 µg/m³ | 18.4 | Sep 14, 2020 | #5 of its top days |
| Oxnard-Thousand Oaks-Ventura, CA | 58.7 µg/m³ | 7.2 | Sep 15, 2020 | #4 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 95 PM2.5 samples in the candidate CBSA on 2020-09-10, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-11, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-11, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-11, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-12, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 118 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 216 PM2.5 samples in the candidate CBSA on 2020-09-10, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-16, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 217 PM2.5 samples in the candidate CBSA on 2020-09-11, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-17, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 96 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 95 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-10, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 48 PM2.5 samples in the candidate CBSA on 2020-09-17, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 122 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier IE — Demolition.
EPA AQS carries an agency-submitted informational qualifier (IE, Demolition.) on 1 PM2.5 sample in the candidate CBSA on 2020-09-15, identifying demolition as affecting the sample. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-10, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 124 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 1 PM2.5 sample in the candidate CBSA on 2020-09-12, identifying wildfire smoke as affecting the sample. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 96 PM2.5 samples in the candidate CBSA on 2020-09-11, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 192 PM2.5 samples in the candidate CBSA on 2020-09-17, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 120 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 96 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 23 PM2.5 samples in the candidate CBSA on 2020-09-17, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IE — Demolition.
EPA AQS carries an agency-submitted informational qualifier (IE, Demolition.) on 1 PM2.5 sample in the candidate CBSA on 2020-09-12, identifying demolition as affecting the sample. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 215 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 216 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 23 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-10, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 96 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 192 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-14, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 221 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-13, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 217 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 24 PM2.5 samples in the candidate CBSA on 2020-09-15, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 119 PM2.5 samples in the candidate CBSA on 2020-09-17, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 96 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-17, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 34 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 25 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 13 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 27 PM2.5 samples in the candidate CBSA on 2020-09-12, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 4 PM2.5 samples in the candidate CBSA on 2020-09-17, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 125 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 25 PM2.5 samples in the candidate CBSA on 2020-09-16, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 4 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 26 PM2.5 samples in the candidate CBSA on 2020-09-15, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 121 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 5 PM2.5 samples in the candidate CBSA on 2020-09-16, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 73 PM2.5 samples in the candidate CBSA on 2020-09-15, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 78 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 25 PM2.5 samples in the candidate CBSA on 2020-09-13, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 38 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 29 PM2.5 samples in the candidate CBSA on 2020-09-14, 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.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 1 PM2.5 sample in the candidate CBSA on 2020-09-17, identifying wildfire smoke as affecting the sample. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 52 PM2.5 samples in the candidate CBSA on 2020-09-13, 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.
AQS PM2.5 qualifier RT — Wildfire-U. S.
EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 25 PM2.5 samples in the candidate CBSA on 2020-09-14, identifying wildfire smoke as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
AQS PM2.5 qualifier IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 125 PM2.5 samples in the candidate CBSA on 2020-09-12, 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.
AQS PM2.5 qualifier IJ — High Winds.
EPA AQS carries an agency-submitted informational qualifier (IJ, High Winds.) on 2 PM2.5 samples in the candidate CBSA on 2020-09-12, identifying windblown or transported dust as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
An archived NWS Air Quality Alert for Los Angeles-Long Beach-Anaheim, CA, issued 2020-09-12T23:45Z, explicitly identifies wildfire smoke. IEM is the archive, not the official system of record.
Air quality advisory for wildfire smoke through Friday
Bay Area regulator identified wildfire smoke as the basis for the September 17-18 advisory and described residual smoke aloft after onshore winds pushed smoke out.
Smoke Advisory: Bobcat and El Dorado Fires
Regional air regulator warned that smoke from the Bobcat and El Dorado fires, with possible northern California smoke contribution, could elevate PM2.5 in the South Coast Air Basin.
Smoke Advisory: Unhealthy Air Quality Declared due to Smoke from Wildfires Burning in the Region
Official Southern California advisory confirms widespread September wildfire-smoke impacts but is not a direct assessment of the Bay Area, Sacramento, Stockton, or Fresno monitors.
CDC describes high PM2.5 and unhealthy-to-hazardous conditions in California communities near 2020 wildfire incidents, including the Creek Fire area; it does not source-apportion each listed metro measurement.
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.