Wildfire smoke EPA monitor flag
Daily PM2.5 peaked at 62.1 µg/m³ near New York across 11 covered metros home to 34 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 2.1 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 72 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. Supplied qualifi
EPA monitor flag EPA attached an exceptional-event qualifier to the affected samples. The agency flagged the measurement itself; no separate agency record describes the event.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jul 20, 2021 official
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 143 PM2.5 samples in the candidate CBSA on 2021-07-20, 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.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jul 20, 2021 official
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 64 PM2.5 samples in the candidate CBSA on 2021-07-20, 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.
U.S. EPA Air Quality System and the submitting air monitoring agency · Jul 20, 2021 official
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 92 PM2.5 samples in the candidate CBSA on 2021-07-20, 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.
See every retained source and limitation ↓
Sequence: New York (Jul 20) → Allentown (Jul 20) → Philadelphia (Jul 20) → New Haven (Jul 20) → Scranton (Jul 20) → Bridgeport (Jul 20) → Hartford (Jul 20) → Albany (Jul 20) → Syracuse (Jul 20) → Worcester (Jul 20) → +1 more metros
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 143 PM2.5 samples in the candidate CBSA on 2021-07-20, identifying wildfire smoke as affecting the samples. An informational qualifier is an official…
View supporting source ↗Air-mass movement
NASA reported smoke from Canadian fires pouring into the eastern U.S. on July 20-21 and identified Philadelphia among the Northeast cities with the haziest skies.
View transport source ↗Local response
NYSDEC issued a July 20 air-quality advisory covering Central New York, which includes the Syracuse region; the advisory does not state a source attribution.
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.
Albany-Schenectady-Troy, NY
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: ALBANY COUNTY HEALTH DEPT
372% above nearby days
372% higher than surrounding days
About the same as surrounding days
78% higher than surrounding days
6% higher than surrounding days
Allentown-Bethlehem-Easton, PA-NJ
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: Allentown
414% above nearby days
214% higher than surrounding days
414% higher than surrounding days
214% higher than surrounding days
8% higher than surrounding days
About the same as surrounding days
34% higher than surrounding days
About the same as surrounding days
Bridgeport-Stamford-Norwalk, CT
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: Roosevelt School-Bridgeport
564% above nearby days
12% lower than surrounding days
369% higher than surrounding days
564% higher than surrounding days
369% higher than surrounding days
106% higher than surrounding days
508% higher than surrounding days
32% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
12% lower than surrounding days
Hartford-West Hartford-East Hartford, CT
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: Huntley Place-Hartford
377% above nearby days
22% lower than surrounding days
258% higher than surrounding days
377% higher than surrounding days
258% higher than surrounding days
97% higher than surrounding days
60% higher than surrounding days
35% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
22% lower than surrounding days
New Haven-Milford, CT
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: Meadow and Bank Streets
359% above nearby days
25% lower than surrounding days
250% higher than surrounding days
359% higher than surrounding days
250% higher than surrounding days
114% higher than surrounding days
144% higher than surrounding days
150% higher than surrounding days
24% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
25% lower than surrounding days
New York-Newark-Jersey City, NY-NJ-PA
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: IS 52
376% above nearby days
About the same as surrounding days
99% higher than surrounding days
376% higher than surrounding days
99% higher than surrounding days
20% higher than surrounding days
92% higher than surrounding days
34% 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
Scranton--Wilkes-Barre--Hazleton, PA
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: Scranton
426% above nearby days
265% higher than surrounding days
426% higher than surrounding days
265% higher than surrounding days
174% higher than surrounding days
About the same as surrounding days
Adjacent observations available
58% higher than surrounding days
6% higher than surrounding days
Philadelphia-Camden-Wilmington, PA-NJ-DE-MD
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: North East Waste (NEW)
319% above nearby days
24% lower than surrounding days
196% higher than surrounding days
319% higher than surrounding days
196% higher than surrounding days
88% higher than surrounding days
45% higher than surrounding days
About the same as surrounding days
47% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
24% lower than surrounding days
Syracuse, NY
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: EAST SYRACUSE
334% above nearby days
About the same as surrounding days
334% higher than surrounding days
1858% higher than surrounding days
32% higher than surrounding days
8% higher than surrounding days
About the same as surrounding days
Richmond, VA
Monitor comparison window 2021-07-18 to 2021-07-24 · PM2.5 target: MathScience Innovation Center
173% above nearby days
About the same as surrounding days
130% higher than surrounding days
173% higher than surrounding days
130% higher than surrounding days
31% higher than surrounding days
About the same as surrounding days
5% higher than surrounding days
About the same as surrounding days
9% lower than surrounding days
About the same as surrounding days
About the same as surrounding days
About the same as surrounding days
Worcester, MA-CT
Monitor comparison window 2021-07-17 to 2021-07-23 · PM2.5 target: WORCESTER SUMMER STREET
295% above nearby days
73% higher than surrounding days
295% higher than surrounding days
73% higher than surrounding days
About the same as surrounding days
43% higher than surrounding days
23% higher than surrounding days
About the same as surrounding days
About the same as surrounding days
6% higher than 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 |
|---|---|---|---|---|
| New York-Newark-Jersey City, NY-NJ-PA | 62.1 µg/m³ | 2.8 | Jul 20, 2021 | #11 of its top days |
| Allentown-Bethlehem-Easton, PA-NJ | 60.2 µg/m³ | 2.7 | Jul 20, 2021 | #15 of its top days |
| Philadelphia-Camden-Wilmington, PA-NJ-DE-MD | 57.8 µg/m³ | 2.6 | Jul 20, 2021 | #20 of its top days |
| New Haven-Milford, CT | 52.6 µg/m³ | 2.4 | Jul 20, 2021 | #13 of its top days |
| Scranton--Wilkes-Barre--Hazleton, PA | 50.3 µg/m³ | 2.3 | Jul 20, 2021 | #16 of its top days |
| Bridgeport-Stamford-Norwalk, CT | 49.5 µg/m³ | 2.3 | Jul 20, 2021 | #14 of its top days |
| Hartford-West Hartford-East Hartford, CT | 43.9 µg/m³ | 2.0 | Jul 20, 2021 | #20 of its top days |
| Albany-Schenectady-Troy, NY | 42.3 µg/m³ | 1.9 | Jul 20, 2021 | #20 of its top days |
| Syracuse, NY | 40.2 µg/m³ | 1.8 | Jul 20, 2021 | #14 of its top days |
| Richmond, VA | 40 µg/m³ | 1.8 | Jul 21, 2021 | #21 of its top days |
| Worcester, MA-CT | 36.5 µg/m³ | 1.7 | Jul 20, 2021 | #22 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 143 PM2.5 samples in the candidate CBSA on 2021-07-20, 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 IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 64 PM2.5 samples in the candidate CBSA on 2021-07-20, 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 IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 92 PM2.5 samples in the candidate CBSA on 2021-07-20, 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 IF — Fire - Canadian.
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 24 PM2.5 samples in the candidate CBSA on 2021-07-20, 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 IF — Fire - Canadian.
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 48 PM2.5 samples in the candidate CBSA on 2021-07-20, 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 IT — Wildfire-U. S.
EPA AQS carries an agency-submitted informational qualifier (IT, Wildfire-U. S.) on 56 PM2.5 samples in the candidate CBSA on 2021-07-20, 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 IF — Fire - Canadian.
EPA AQS carries an agency-submitted informational qualifier (IF, Fire - Canadian.) on 78 PM2.5 samples in the candidate CBSA on 2021-07-21, 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.
NASA reported smoke from Canadian fires pouring into the eastern U.S. on July 20-21 and identified Philadelphia among the Northeast cities with the haziest skies.
Air Quality Advisory - Tuesday, July 20, 2021
NYSDEC issued a July 20 air-quality advisory covering Central New York, which includes the Syracuse region; the advisory does not state a source attribution.
EPA monitor flag EPA attached an exceptional-event qualifier to the affected samples. The agency flagged the measurement itself; no separate agency record describes the event.
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.