Wildfire smoke
2020-08-19 6-area wildfire-smoke episode
Daily PM2.5 peaked at 158.6 µg/m³ near Bakersfield across 6 covered metros home to 12 million people. 1 metro recorded their worst day on record; 3 placed a top-ten day.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 11.4 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 137 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.
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.
What happened, in the record
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. 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. 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.
Sequence: San Jose (Aug 19) → Sacramento (Aug 20) → Stockton (Aug 20) → Bakersfield (Aug 21) → Fresno (Aug 21) → San Francisco (Aug 23)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Bakersfield, CA | 158.6 µg/m³ | 13.1 | Aug 22, 2020 | Worst day on record |
| Fresno, CA | 153.5 µg/m³ | 18.8 | Aug 22, 2020 | #6 of its top days |
| Sacramento--Roseville--Arden-Arcade, CA | 117 µg/m³ | 23.8 | Aug 22, 2020 | #11 of its top days |
| Stockton-Lodi, CA | 102 µg/m³ | 16.8 | Aug 20, 2020 | #11 of its top days |
| San Francisco-Oakland-Hayward, CA | 99.9 µg/m³ | 8.0 | Aug 23, 2020 | #15 of its top days |
| San Jose-Sunnyvale-Santa Clara, CA | 85.3 µg/m³ | 3.9 | Aug 19, 2020 | #10 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.
The evidence
Official records
- NOAA Storm Events Wildfire, CALIFORNIA, Aug 16, 2020 "A prolonged and oppressive heat wave swept the Central Coast and Bay Area for almost a week from August 14th to August 19th with widespread record breaking temperatures observed across the region. This was caused by a st…" record →
- NOAA Storm Events Wildfire, CALIFORNIA, Aug 16, 2020 "A prolonged and oppressive heat wave swept the Central Coast and Bay Area for almost a week from August 14th to August 19th with widespread record breaking temperatures observed across the region. This was caused by a st…" record →
- NOAA Storm Events Wildfire, CALIFORNIA, Aug 18, 2020 "A prolonged and oppressive heat wave swept the Central Coast and Bay Area for almost a week from August 14th to August 19th with widespread record breaking temperatures observed across the region. This was caused by a st…" record →
- NOAA Storm Events Dense Smoke, CALIFORNIA, Aug 19, 2020 "A prolonged and oppressive heat wave swept the Central Coast and Bay Area for almost a week from August 14th to August 19th with widespread record breaking temperatures observed across the region. This was caused by a st…" record →
- NOAA Storm Events Wildfire, CALIFORNIA, Aug 17, 2020 "During mid August, moisture from tropical storm Fausto moved along the coast of southern CA and made landfall over central and northern California. This system, combined with the an oppressive high pressure system that h…" record →
EPA AQS monitor qualifier 38
- 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 2020-08-23, 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 2020-08-22, 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 24 PM2.5 samples in the candidate CBSA on 2020-08-23, 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 2020-08-24, 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 2020-08-23, 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 208 PM2.5 samples in the candidate CBSA on 2020-08-24, 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 217 PM2.5 samples in the candidate CBSA on 2020-08-21, 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 217 PM2.5 samples in the candidate CBSA on 2020-08-20, 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 2020-08-22, 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 70 PM2.5 samples in the candidate CBSA on 2020-08-21, 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 218 PM2.5 samples in the candidate CBSA on 2020-08-22, 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.
- AQS PM2.5 qualifier RT — Wildfire-U. S. EPA AQS carries an agency-submitted request-exclusion qualifier (RT, Wildfire-U. S.) on 72 PM2.5 samples in the candidate CBSA on 2020-08-20, 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.
- +26 more EPA AQS records on file
Agency and publisher pages 3
- Public Health Officials Urge Californians to Stay Indoors When Possible due to Unhealthy Air Quality in Wildfire Areas State public-health release identifies unhealthy air in fire-stricken and surrounding California regions as wildfire-smoke exposure.
- Air quality advisory for wildfire smoke extended through Tuesday Bay Area regulator attributed the contemporaneous advisory to smoke from numerous lightning-sparked wildfires across the region.
- Fresno-area smoke levels from wildfires off the chart. When will it get better? Archived contemporaneous reporting identifies wildfire smoke, including the Creek and Lake fires, as the likely source of exceptionally high Fresno-area PM2.5.
What remains uncertain
- An AQS informational qualifier is an official submitting-agency flag, not an EPA-concurred exclusion determination.
Status and provenance
Research preview: this record carries research-only status and its boundaries, cause, and name may change as evidence review completes. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula.