Event catalog
362 named PM2.5 episodes across the 100 largest US metros, assembled from the monitor record and resolved to a shared root cause only where retained evidence supports it: official assessments, agency statements, news coverage, and NOAA records. 205 further significant episodes remain unattributed pending cause review.
51.5 µg/m³ peak ≈ 1.8 cigarettes per person 2.8M people affected
Qualified supplied evidence supports wildfire smoke for the July 20 St. Louis event. No other supplied event was merged without evidence of the same coherent occurrence.
57.7 µg/m³ peak ≈ 4.5 cigarettes per person 846k people affected
Qualified supplied evidence supports wildfire smoke for the July 20–21 Boise City event. No other supplied event was merged without evidence of the same coherent occurrence.
NWS alert 1Agency/press 1
130.6 µg/m³ peak ≈ 5.6 cigarettes per person 605k people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Origin: Canada; Northern Minnesota
387.8 µg/m³ peak ≈ 13.0 cigarettes per person 86M people affected 14 city records set, 27 top-ten days
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence a
EPA AQS 1NWS alert 6Agency/press 6
54.7 µg/m³ peak ≈ 2.0 cigarettes per person 6.4M people affected
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
51 µg/m³ peak ≈ 1.9 cigarettes per person 6.5M people affected 1 top-ten day
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
72.1 µg/m³ peak ≈ 2.6 cigarettes per person 4.0M people affected 1 city record set, 2 top-ten days
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
25.8 µg/m³ peak ≈ 0.9 cigarettes per person 778k people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Named source South Canal Fire
64.9 µg/m³ peak ≈ 2.6 cigarettes per person 1.8M people affected 1 top-ten day
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Agency/press 1
43.8 µg/m³ peak ≈ 1.5 cigarettes per person 588k people affected
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
50.2 µg/m³ peak ≈ 1.8 cigarettes per person 637k people affected 1 top-ten day
The supplied retained evidence explicitly supports multiple material causes (prescribed-fire smoke and wildfire smoke) for this episode, so it is retained as mixed.
EPA AQS 2
46.4 µg/m³ peak ≈ 1.7 cigarettes per person 661k people affected
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
35.8 µg/m³ peak ≈ 1.2 cigarettes per person 606k people affected
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
43.9 µg/m³ peak ≈ 1.6 cigarettes per person 915k people affected
The supplied retained evidence supports other transported pollution for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Agency/press 2
54.5 µg/m³ peak ≈ 2.1 cigarettes per person 661k people affected 1 top-ten day
The supplied retained evidence explicitly supports multiple material causes (dust and wildfire smoke) for this episode, so it is retained as mixed.
EPA AQS 1News 1
110.1 µg/m³ peak ≈ 4.6 cigarettes per person 870k people affected 1 city record set
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
33.9 µg/m³ peak ≈ 1.2 cigarettes per person 2.9M people affected
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
48.5 µg/m³ peak ≈ 1.7 cigarettes per person 637k people affected 1 top-ten day
The supplied retained evidence explicitly supports multiple material causes (prescribed-fire smoke and wildfire smoke) for this episode, so it is retained as mixed.
EPA AQS 2
85 µg/m³ peak ≈ 3.3 cigarettes per person 7.8M people affected 1 top-ten day
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
44.4 µg/m³ peak ≈ 1.5 cigarettes per person 637k people affected
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
168.1 µg/m³ peak ≈ 17.5 cigarettes per person 605k people affected 1 top-ten day
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
45.9 µg/m³ peak ≈ 1.7 cigarettes per person 1.6M people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 1Agency/press 1
Origin: Canada
51.5 µg/m³ peak ≈ 6.1 cigarettes per person 3.8M people affected 3 top-ten days
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members.
Agency/press 1
Origin: Canada
89.8 µg/m³ peak ≈ 4.0 cigarettes per person 29M people affected 8 top-ten days
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence a
EPA AQS 18NWS alert 4Agency/press 7
51.1 µg/m³ peak ≈ 1.9 cigarettes per person 3.8M people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 1Agency/press 1
49.6 µg/m³ peak ≈ 1.8 cigarettes per person 601k people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Origin: Central Canada
89.8 µg/m³ peak ≈ 4.6 cigarettes per person 5.3M people affected 1 top-ten day
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members.
EPA AQS 3NWS alert 1Agency/press 3
59 µg/m³ peak ≈ 2.2 cigarettes per person 6.4M people affected
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
82.1 µg/m³ peak ≈ 3.6 cigarettes per person 6.7M people affected 3 top-ten days
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 4News 1
69.2 µg/m³ peak ≈ 2.5 cigarettes per person 6.3M people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
49.4 µg/m³ peak ≈ 2.7 cigarettes per person 1.7M people affected 1 top-ten day
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Origin: Canada
93.5 µg/m³ peak ≈ 2.4 cigarettes per person 20M people affected 2 top-ten days
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members.
EPA AQS 8NWS alert 1Agency/press 3
78.5 µg/m³ peak ≈ 6.0 cigarettes per person 879k people affected
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
51.7 µg/m³ peak ≈ 3.7 cigarettes per person 588k people affected 1 top-ten day
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
39 µg/m³ peak ≈ 1.4 cigarettes per person 661k people affected
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Origin: El Paso Borderland
285.8 µg/m³ peak ≈ 12.6 cigarettes per person 879k people affected 1 top-ten day
NWS and WMO evidence identifies a major March 18 El Paso Borderland wind, sand, and dust storm on the PM2.5 event date.
75.5 µg/m³ peak ≈ 2.8 cigarettes per person 2.8M people affected 1 top-ten day
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Origin: Oklahoma and eastern Kansas fires; Southwestern United States dust
72.4 µg/m³ peak ≈ 2.3 cigarettes per person 3.2M people affected 1 city record set, 2 top-ten days
Agency and NASA evidence supports a mixed event involving transported dust and smoke from Oklahoma and eastern Kansas fires.
Origin: Southwestern United States; Texas and Oklahoma Panhandles
64.7 µg/m³ peak ≈ 2.3 cigarettes per person 3.0M people affected 1 city record set, 2 top-ten days
The supplied evidence supports dust and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports dust and documents an overlapping or continuing regional occurrence across the proposed members.
EPA AQS 1Agency/press 4
60.5 µg/m³ peak ≈ 2.3 cigarettes per person 879k people affected
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
97.8 µg/m³ peak ≈ 6.2 cigarettes per person 588k people affected 1 top-ten day
The supplied retained evidence explicitly supports multiple material causes (prescribed-fire smoke and wildfire smoke) for this episode, so it is retained as mixed.
EPA AQS 3
238.6 µg/m³ peak ≈ 15.7 cigarettes per person 879k people affected 1 top-ten day
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
59.2 µg/m³ peak ≈ 2.3 cigarettes per person 879k people affected
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
47.2 µg/m³ peak ≈ 1.7 cigarettes per person 637k people affected 1 top-ten day
The supplied retained evidence supports prescribed-fire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 1NWS alert 1
63.3 µg/m³ peak ≈ 2.4 cigarettes per person 879k people affected
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Named source Hughes Fire
45.3 µg/m³ peak ≈ 1.6 cigarettes per person 835k people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 1NWS alert 1Agency/press 2
Cited: Ventura County Air Pollution Control District
31 µg/m³ peak ≈ 1.1 cigarettes per person 1.1M people affected 1 top-ten day
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
210.3 µg/m³ peak ≈ 9.8 cigarettes per person 6.3M people affected 1 city record set
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 3Agency/press 2
50.7 µg/m³ peak ≈ 1.7 cigarettes per person 2.2M people affected
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Origin: Southern California
85.9 µg/m³ peak ≈ 3.2 cigarettes per person 7.1M people affected 1 top-ten day
The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members. The supplied evidence supports wildfire smoke and documents an overlapping or continuing regional occurrence across the proposed members.
EPA AQS 2NWS alert 1Agency/press 2
89.5 µg/m³ peak ≈ 6.7 cigarettes per person 846k people affected 1 city record set
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 4NWS alert 1Agency/press 1
Named source Bogus Basin Road vegetation fire
64.7 µg/m³ peak ≈ 2.6 cigarettes per person 846k people affected 1 top-ten day
The supplied retained evidence supports wildfire smoke for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 2NWS alert 1Agency/press 1
46.2 µg/m³ peak ≈ 1.5 cigarettes per person 2.1M people affected 1 top-ten day
The supplied retained evidence explicitly supports multiple material causes (dust and wildfire smoke) for this episode, so it is retained as mixed.
EPA AQS 2News 1
38.7 µg/m³ peak ≈ 1.3 cigarettes per person 5.3M people affected
The supplied retained evidence supports dust for this event; no supplied evidence establishes membership in a broader time-bounded episode.
EPA AQS 2Agency/press 1
60.1 µg/m³ peak ≈ 2.4 cigarettes per person 846k people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2NWS alert 1
Origin: Canada
29.7 µg/m³ peak ≈ 2.1 cigarettes per person 778k people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
NWS alert 1Agency/press 1
Origin: eastern Oregon
89.1 µg/m³ peak ≈ 3.7 cigarettes per person 846k people affected 1 top-ten day
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2NWS alert 1Agency/press 1
64 µg/m³ peak ≈ 2.4 cigarettes per person 4.4M people affected
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1Agency/press 1
43.9 µg/m³ peak ≈ 1.6 cigarettes per person 2.4M people affected
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1Agency/press 1
27.2 µg/m³ peak ≈ 1.0 cigarettes per person 1.1M people affected
Qualified supplied evidence supports dust as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
NWS alert 1News 1
Origin: Arizona; New Mexico
39 µg/m³ peak ≈ 1.4 cigarettes per person 2.4M people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1Agency/press 1
Cited: Clark County
Origin: Central America; Mexico
63.8 µg/m³ peak ≈ 2.7 cigarettes per person 3.7M people affected 1 top-ten day
TCEQ evidence identifies a connected June 3-6 regional transport episode involving smoke from fires in Mexico and Central America. The overlapping McAllen and San Antonio focal events are grouped as manifestations of that occurrence. TCEQ evidence identifies a connected June 3-6 regional transport episode involving smoke from fires in Mexico and Central America. The overlapping McAllen and San Antonio focal events are grouped as manifestations of that occurrence.
EPA AQS 4Agency/press 1
Origin: Central America; Mexico
57.7 µg/m³ peak ≈ 3.2 cigarettes per person 22M people affected 3 top-ten days
TCEQ evidence describes connected May 19-27 transport of smoke from fires in Mexico and Central America across South and Central Texas, with contemporaneous Houston corroboration on May 27. The overlapping focal events are grouped as one regional occurrence. TCEQ evidence describes connected May 19-27 transport of smoke from fires in Mexico and Central America across South and Central Texas, with contemporaneous Houston corroboration on May 27. The overlapping focal events are grouped as one regional occurrence. TCEQ evidence describes connected May 19-27 transport of smoke from fires in Mexico and Central America across South and Central Texas, with contemporaneous Houston corroboration on May 27. The overlapping focal events are grouped as one regional occurrence. TCEQ evidence describes
EPA AQS 20Agency/press 2
Origin: Central America; Mexico
51.4 µg/m³ peak ≈ 1.9 cigarettes per person 915k people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1Agency/press 1
Origin: northeast British Columbia
56.5 µg/m³ peak ≈ 2.1 cigarettes per person 3.8M people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1Agency/press 1
Cited: Minnesota Pollution Control Agency
Origin: Central America; Mexico
55.7 µg/m³ peak ≈ 2.4 cigarettes per person 14M people affected 3 top-ten days
TCEQ and contemporaneous reporting identify the same Mexico and Central America fire-smoke transport affecting South, Central, and Southeast Texas over May 8-10. The overlapping metro events are grouped as one regional occurrence. TCEQ and contemporaneous reporting identify the same Mexico and Central America fire-smoke transport affecting South, Central, and Southeast Texas over May 8-10. The overlapping metro events are grouped as one regional occurrence. TCEQ and contemporaneous reporting identify the same Mexico and Central America fire-smoke transport affecting South, Central, and Southeast Texas over May 8-10. The overlapping metro events are grouped as one regional occurrence.
EPA AQS 7Agency/press 2
38.2 µg/m³ peak ≈ 1.4 cigarettes per person 661k people affected
KDHE attributes the Wichita-metro exceedance as likely influenced by wildland fires within the Flint Hills but does not distinguish prescribed fire from wildfire and notes other contributors. The supported broad cause therefore remains other.
Agency/press 1
Cited: Kansas Department of Health and Environment
120.1 µg/m³ peak ≈ 3.2 cigarettes per person 1.7M people affected 1 city record set
Qualified supplied evidence supports prescribed-fire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2Agency/press 2
Cited: Kansas Department of Health and Environment
Origin: Central America; Mexico
36.1 µg/m³ peak ≈ 1.2 cigarettes per person 5.3M people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2
39.4 µg/m³ peak ≈ 1.3 cigarettes per person 1.1M people affected 1 top-ten day
KDHE attributes the Tulsa-metro exceedance as likely influenced by wildland fires within the Flint Hills but does not distinguish prescribed fire from wildfire and notes other contributors. The supported broad cause therefore remains other.
Agency/press 1
Cited: Kansas Department of Health and Environment
51.6 µg/m³ peak ≈ 1.9 cigarettes per person 870k people affected 1 top-ten day
Qualified supplied evidence supports prescribed-fire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1NWS alert 1Agency/press 1
54.9 µg/m³ peak ≈ 2.2 cigarettes per person 846k people affected
Qualified supplied evidence supports winter inversion as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Agency/press 1
102.8 µg/m³ peak ≈ 3.6 cigarettes per person 6.3M people affected 1 top-ten day
Official evidence identifies fireworks across the Arizona metros and separately identifies an inversion trapping emissions at the West Phoenix monitor. Both are retained as material components of the episode.
EPA AQS 2Agency/press 1
27.4 µg/m³ peak ≈ 1.0 cigarettes per person 999k people affected
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
108.2 µg/m³ peak ≈ 4.5 cigarettes per person 966k people affected 1 city record set
Agency-submitted AQS qualifiers identify both prescribed-fire smoke and fireworks on the New Orleans event date. Both are retained as material cause components of this local mixed episode.
103.1 µg/m³ peak ≈ 4.1 cigarettes per person 7.8M people affected 1 top-ten day
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Agency/press 1
47.9 µg/m³ peak ≈ 1.8 cigarettes per person 3.4M people affected 1 top-ten day
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
64 µg/m³ peak ≈ 3.1 cigarettes per person 10M people affected 3 top-ten days
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Origin: Canada
50.7 µg/m³ peak ≈ 1.7 cigarettes per person 2.2M people affected
Qualified supplied evidence supports wildfire smoke for the November 15 Indianapolis-Carmel-Anderson event. No other supplied event was merged without evidence of the same coherent occurrence.
EPA AQS 2
Origin: Canada
47.9 µg/m³ peak ≈ 1.6 cigarettes per person 17M people affected 1 city record set, 4 top-ten days
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 3 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-10-01 through 2023-10-04 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 3 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-10-01 through 2023-10-04 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 3 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-10-01 through 2023-10-04 occurrence. Qualified supplied e
EPA AQS 10Agency/press 4
Origin: Canada
63.4 µg/m³ peak ≈ 3.3 cigarettes per person 4.7M people affected 3 top-ten days
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-09-06 through 2023-09-07 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-09-06 through 2023-09-07 occurrence.
EPA AQS 6NWS alert 1Agency/press 5
Named source Gray Fire, Ridge Creek Fire, Oregon Road Fire · Canada
239.7 µg/m³ peak ≈ 5.4 cigarettes per person 4.8M people affected 1 top-ten day
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-08-19 through 2023-08-20 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-08-19 through 2023-08-20 occurrence.
EPA AQS 3NWS alert 1Agency/press 3
Origin: Canada
59.1 µg/m³ peak ≈ 1.9 cigarettes per person 3.5M people affected 1 top-ten day
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-07-24 through 2023-07-25 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-07-24 through 2023-07-25 occurrence.
EPA AQS 4Agency/press 2News 1
Origin: Canada
67.2 µg/m³ peak ≈ 2.2 cigarettes per person 32M people affected 10 top-ten days
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 8 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-07-15 through 2023-07-18 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 8 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-07-15 through 2023-07-18 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 8 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-07-15 through 2023-07-18 occurrence. Qualified supplied e
EPA AQS 25NWS alert 2Agency/press 7News 1
Origin: Seattle-Tacoma-Bellevue, WA
118.2 µg/m³ peak ≈ 5.0 cigarettes per person 4.1M people affected 1 top-ten day
Qualified supplied evidence supports fireworks for the July 5 Seattle-Tacoma-Bellevue event. No other supplied event was merged without evidence of the same coherent occurrence.
76.8 µg/m³ peak ≈ 7.2 cigarettes per person 754k people affected 1 top-ten day
Qualified supplied evidence supports wildfire smoke for the June 27–29 Des Moines-West Des Moines event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: Canada
210.1 µg/m³ peak ≈ 7.6 cigarettes per person 97M people affected 4 city records set, 33 top-ten days
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 13 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-26 through 2023-07-01 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 13 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-26 through 2023-07-01 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 13 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-26 through 2023-07-01 occurrence. Qualified supplie
EPA AQS 124NWS alert 5Agency/press 6News 1
Origin: Canada
111.3 µg/m³ peak ≈ 4.1 cigarettes per person 4.5M people affected 1 top-ten day
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-14 through 2023-06-14 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 1 other supplied event because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-14 through 2023-06-14 occurrence.
Origin: Mexico and Central America
34.8 µg/m³ peak ≈ 1.2 cigarettes per person 2.6M people affected
Qualified supplied evidence supports wildfire smoke for the June 13 Austin-Round Rock event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: Canada
258.9 µg/m³ peak ≈ 11.3 cigarettes per person 63M people affected 12 city records set, 20 top-ten days
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 9 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-04 through 2023-06-09 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 9 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-04 through 2023-06-09 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 9 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-06-04 through 2023-06-09 occurrence. Qualified supplied e
EPA AQS 59NWS alert 2Agency/press 7News 1
Origin: Canada
95.6 µg/m³ peak ≈ 3.9 cigarettes per person 8.6M people affected 2 city records set
Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 2 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-05-18 through 2023-05-20 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 2 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-05-18 through 2023-05-20 occurrence. Qualified supplied evidence supports wildfire smoke for this event. It is grouped with 2 other supplied events because the evidence identifies Canada as the shared origin and the affected intervals form one continuous 2023-05-18 through 2023-05-20 occurrence.
EPA AQS 6NWS alert 1Agency/press 4
Origin: Houston-The Woodlands-Sugar Land, TX
43.8 µg/m³ peak ≈ 1.4 cigarettes per person 7.8M people affected
Qualified supplied evidence supports prescribed-fire smoke for the March 15 Houston-The Woodlands-Sugar Land event. No other supplied event was merged without evidence of the same coherent occurrence.
44.6 µg/m³ peak ≈ 1.6 cigarettes per person 870k people affected 1 top-ten day
Qualified supplied evidence supports wildfire smoke for the March 1 Columbia event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: Jackson, MS
37.6 µg/m³ peak ≈ 1.2 cigarettes per person 606k people affected
Qualified supplied evidence supports prescribed-fire smoke for the February 28 Jackson event. No other supplied event was merged without evidence of the same coherent occurrence.
45.2 µg/m³ peak ≈ 1.6 cigarettes per person 8.3M people affected
Qualified supplied evidence supports multiple material components—windblown or transported dust and wildfire smoke—for the February 27 Dallas-Fort Worth-Arlington event; the supplied record does not quantify their relative contributions.
EPA AQS 1News 1
Origin: Minneapolis-St. Paul-Bloomington, MN-WI
64.4 µg/m³ peak ≈ 2.5 cigarettes per person 3.8M people affected
Qualified supplied evidence supports winter inversion for the January 10 Minneapolis-St. Paul-Bloomington event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: Miami-Fort Lauderdale-West Palm Beach, FL
37.1 µg/m³ peak ≈ 1.3 cigarettes per person 6.5M people affected
Qualified supplied evidence supports fireworks for the January 1 Miami-Fort Lauderdale-West Palm Beach event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: Austin-Round Rock, TX; San Antonio-New Braunfels, TX
44.1 µg/m³ peak ≈ 1.5 cigarettes per person 5.3M people affected 1 top-ten day
Qualified supplied evidence supports fireworks for the January 1 Austin-Round Rock regional event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: New Orleans-Metairie, LA
45.5 µg/m³ peak ≈ 1.6 cigarettes per person 966k people affected 1 top-ten day
Qualified supplied evidence supports fireworks for the January 1 New Orleans-Metairie event. No other supplied event was merged without evidence of the same coherent occurrence.
Origin: Urban Honolulu, HI
42 µg/m³ peak ≈ 1.7 cigarettes per person 999k people affected
Qualified supplied evidence supports fireworks for the January 1 Urban Honolulu event. No other supplied event was merged without evidence of the same coherent occurrence.
68.4 µg/m³ peak ≈ 2.3 cigarettes per person 6.3M people affected
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2Agency/press 3
Named source Nakia Creek Fire · Oregon; Washington
255.9 µg/m³ peak ≈ 17.7 cigarettes per person 6.7M people affected 1 city record set, 2 top-ten days
Agency evidence identifies October 12-20 as a wildfire-smoke impact window in the Seattle area, and the later regional event extends through Portland with identified Washington fire sources. These overlapping impacts form one time-bounded Pacific Northwest occurrence. Agency evidence identifies October 12-20 as a wildfire-smoke impact window in the Seattle area, and the later regional event extends through Portland with identified Washington fire sources. These overlapping impacts form one time-bounded Pacific Northwest occurrence. Agency evidence identifies October 12-20 as a wildfire-smoke impact window in the Seattle area, and the later regional event extends through Portland with identified Washington fire sources. These overlapping impacts form one time-bounded Pacific Northwest occur
EPA AQS 6Agency/press 5
66.5 µg/m³ peak ≈ 2.6 cigarettes per person 4.1M people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1NWS alert 1Agency/press 2
103.5 µg/m³ peak ≈ 4.4 cigarettes per person 605k people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
67.7 µg/m³ peak ≈ 2.7 cigarettes per person 4.1M people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1NWS alert 1Agency/press 1
60.6 µg/m³ peak ≈ 2.4 cigarettes per person 846k people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2NWS alert 1Agency/press 1
59.5 µg/m³ peak ≈ 4.2 cigarettes per person 2.4M people affected 1 top-ten day
Qualified supplied evidence supports dust as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 2Agency/press 1
46.2 µg/m³ peak ≈ 1.7 cigarettes per person 1.2M people affected
Qualified supplied evidence supports fireworks as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Origin: Sahara; western Africa
51.8 µg/m³ peak ≈ 2.5 cigarettes per person 9.2M people affected 1 top-ten day
Event-specific official evidence identifies African dust, while supplied scientific context reconstructs one June 12-17 trans-Atlantic Saharan-dust outbreak reaching the Gulf region. The directly attributed focal events are grouped as manifestations of that occurrence. Event-specific official evidence identifies African dust, while supplied scientific context reconstructs one June 12-17 trans-Atlantic Saharan-dust outbreak reaching the Gulf region. The directly attributed focal events are grouped as manifestations of that occurrence. Event-specific official evidence identifies African dust, while supplied scientific context reconstructs one June 12-17 trans-Atlantic Saharan-dust outbreak reaching the Gulf region. The directly attributed focal events are grouped as manifestations of that oc
EPA AQS 12NWS alert 1Agency/press 3
Origin: Central America; Mexico; western Africa
40.6 µg/m³ peak ≈ 1.4 cigarettes per person 915k people affected
Official evidence supports both transported dust and Mexico/Central America fire smoke in McAllen on June 12. The event is resolved as mixed and remains separate from dust-only neighboring events.
EPA AQS 1Agency/press 1
Origin: Four Corners; New Mexico
27.3 µg/m³ peak ≈ 1.0 cigarettes per person 778k people affected
Contemporaneous evidence identifies both transported and local dust and New Mexico wildfire smoke as components of the Colorado Springs episode. The event is therefore resolved as mixed.
35.3 µg/m³ peak ≈ 1.2 cigarettes per person 661k people affected
Qualified supplied evidence supports prescribed-fire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Agency/press 1
Cited: Kansas Department of Health and Environment
40.8 µg/m³ peak ≈ 1.5 cigarettes per person 2.4M people affected
Qualified supplied evidence supports dust as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Origin: Central America; Mexico
49.9 µg/m³ peak ≈ 1.9 cigarettes per person 915k people affected
Qualified supplied evidence supports wildfire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
24 µg/m³ peak ≈ 0.8 cigarettes per person 740k people affected
Qualified supplied evidence supports prescribed-fire smoke as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
Agency/press 1
Cited: Florida Forest Service
35.6 µg/m³ peak ≈ 1.2 cigarettes per person 606k people affected
Contemporaneous reporting links fires and dry conditions to Jackson-area poor air quality, while also naming smog and manufacturing as possible contributors. The broad cause is resolved only as other, and the episode remains local and event-specific.
50.3 µg/m³ peak ≈ 1.8 cigarettes per person 705k people affected 1 top-ten day
AQS and scientific evidence attribute the episode to the Winston Weaver fertilizer-distribution-facility fire. The evidence supports a discrete structural and facility-fire occurrence rather than a broader regional episode.
36.9 µg/m³ peak ≈ 1.4 cigarettes per person 926k people affected
Qualified supplied evidence supports dust as the root cause of this event. The supplied record does not establish a coherent shared occurrence with neighboring candidates, so the episode remains event-specific.
EPA AQS 1News 1
Origin: Augusta-Richmond County, GA-SC
43.6 µg/m³ peak ≈ 1.5 cigarettes per person 637k people affected
Supplied qualified evidence supports prescribed-fire smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Chattanooga, TN-GA
39.3 µg/m³ peak ≈ 1.3 cigarettes per person 588k people affected
Supplied qualified evidence supports prescribed-fire smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Winston-Salem, NC
44.9 µg/m³ peak ≈ 1.6 cigarettes per person 705k people affected
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.
EPA AQS 1News 1
Origin: Fresno, CA
147.7 µg/m³ peak ≈ 6.1 cigarettes per person 1.2M people affected 1 top-ten day
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.
EPA AQS 2News 1
Origin: Boise City, ID
58.6 µg/m³ peak ≈ 2.3 cigarettes per person 846k people affected
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.
EPA AQS 2NWS alert 1
Origin: Cape Coral-Fort Myers, FL; Palm Bay-Melbourne-Titusville, FL
27 µg/m³ peak ≈ 0.9 cigarettes per person 1.5M people affected 2 top-ten days
Supplied qualified evidence supports dust as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Sacramento--Roseville--Arden-Arcade, CA
265.7 µg/m³ peak ≈ 21.3 cigarettes per person 2.5M people affected 1 city record set
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.
EPA AQS 3Agency/press 1
Origin: Lakeland-Winter Haven, FL; Palm Bay-Melbourne-Titusville, FL
23.8 µg/m³ peak ≈ 1.1 cigarettes per person 1.5M people affected
Supplied qualified evidence supports dust as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Las Vegas-Henderson-Paradise, NV
59.3 µg/m³ peak ≈ 2.3 cigarettes per person 2.4M people affected 1 top-ten day
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.
EPA AQS 1Agency/press 1
Origin: Boise City, ID
82.6 µg/m³ peak ≈ 5.8 cigarettes per person 846k people affected 1 top-ten day
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.
EPA AQS 4NWS alert 1
Origin: Spokane-Spokane Valley, WA
123.7 µg/m³ peak ≈ 10.1 cigarettes per person 605k people affected
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.
EPA AQS 2Agency/press 1
Origin: Albuquerque, NM
84 µg/m³ peak ≈ 5.2 cigarettes per person 926k people affected 1 city record set
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.
NWS alert 1Agency/press 1
Origin: Sacramento--Roseville--Arden-Arcade, CA
127.2 µg/m³ peak ≈ 5.4 cigarettes per person 2.5M people affected 1 top-ten day
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.
EPA AQS 1Agency/press 1
Origin: Las Vegas-Henderson-Paradise, NV
100.7 µg/m³ peak ≈ 4.2 cigarettes per person 2.4M people affected 1 city record set
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.
EPA AQS 1News 1
Origin: Colorado Springs, CO; Denver-Aurora-Lakewood, CO
64.8 µg/m³ peak ≈ 4.4 cigarettes per person 3.8M people affected 2 top-ten days
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.
NWS alert 2Agency/press 1
Origin: Spokane-Spokane Valley, WA
105 µg/m³ peak ≈ 4.4 cigarettes per person 605k people affected
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.
EPA AQS 1NWS alert 1Agency/press 1
Origin: Des Moines-West Des Moines, IA; Kansas City, MO-KS; Oklahoma City, OK; Omaha-Council Bluffs, NE-IA; Tulsa, OK; Wichita, KS
53.5 µg/m³ peak ≈ 3.1 cigarettes per person 7.2M people affected 4 top-ten days
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.
EPA AQS 7NWS alert 1News 2
Origin: Colorado Springs, CO
29 µg/m³ peak ≈ 1.1 cigarettes per person 778k people affected
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.
NWS alert 1News 1
Origin: Spokane-Spokane Valley, WA
85.9 µg/m³ peak ≈ 3.6 cigarettes per person 605k people affected
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.
EPA AQS 1NWS alert 1Agency/press 1
Origin: Omaha-Council Bluffs, NE-IA
45.3 µg/m³ peak ≈ 1.7 cigarettes per person 1.0M people affected
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.
EPA AQS 1News 1
Origin: Minneapolis-St. Paul-Bloomington, MN-WI
115.6 µg/m³ peak ≈ 10.2 cigarettes per person 3.8M people affected 1 top-ten day
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.
EPA AQS 3NWS alert 1Agency/press 1
Origin: Boston-Cambridge-Newton, MA-NH; Hartford-West Hartford-East Hartford, CT; New Haven-Milford, CT; Providence-Warwick, RI-MA; Worcester, MA-CT
59 µg/m³ peak ≈ 2.0 cigarettes per person 9.4M people affected 3 top-ten days
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.
EPA AQS 2Agency/press 1
Origin: Nashville-Davidson--Murfreesboro--Franklin, TN
41.5 µg/m³ peak ≈ 1.4 cigarettes per person 2.2M people affected
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.
EPA AQS 1News 1
Origin: Albany-Schenectady-Troy, NY; Allentown-Bethlehem-Easton, PA-NJ; Bridgeport-Stamford-Norwalk, CT; Hartford-West Hartford-East Hartford, CT; New Haven-Milford, CT; New York-Newark-Jersey City, NY-NJ-PA; Philadelphia-Camden-Wilmington, PA-NJ-DE-MD; Richmond, VA; Scranton--Wilkes-Barre--Hazleton, PA; Syracuse, NY; Worcester, MA-CT
62.1 µg/m³ peak ≈ 2.1 cigarettes per person 34M people affected
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. 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 AQS 7Agency/press 2
Origin: Nashville-Davidson--Murfreesboro--Franklin, TN
41.1 µg/m³ peak ≈ 1.4 cigarettes per person 2.2M people affected
Supplied qualified evidence supports multiple material causes for this event: fireworks and wildfire-smoke.
Origin: Augusta-Richmond County, GA-SC; Charlotte-Concord-Gastonia, NC-SC; Lakeland-Winter Haven, FL; North Port-Sarasota-Bradenton, FL
46.6 µg/m³ peak ≈ 1.3 cigarettes per person 5.3M people affected 1 top-ten day
Supplied qualified evidence supports fireworks 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 fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Washington-Arlington-Alexandria, DC-VA-MD-WV
58.9 µg/m³ peak ≈ 2.2 cigarettes per person 6.4M people affected
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Albuquerque, NM
37.3 µg/m³ peak ≈ 1.4 cigarettes per person 926k people affected
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.
NWS alert 1Agency/press 2
Named source Mescal Fire, Telegraph Fire · Albuquerque, NM
57.9 µg/m³ peak ≈ 3.8 cigarettes per person 926k people affected 1 top-ten day
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.
NWS alert 1Agency/press 2
Origin: Knoxville, TN
55.2 µg/m³ peak ≈ 2.0 cigarettes per person 958k people affected
Supplied qualified evidence supports prescribed-fire smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
EPA AQS 1Agency/press 1
Origin: Denver-Aurora-Lakewood, CO
55.7 µg/m³ peak ≈ 3.9 cigarettes per person 3.1M people affected
Supplied qualified evidence supports other-cause as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Augusta-Richmond County, GA-SC
41.2 µg/m³ peak ≈ 1.4 cigarettes per person 637k people affected
Supplied qualified evidence supports prescribed-fire smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Kansas City, MO-KS
41.1 µg/m³ peak ≈ 1.4 cigarettes per person 2.3M people affected
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.
Origin: Tulsa, OK
79.6 µg/m³ peak ≈ 4.4 cigarettes per person 1.1M people affected 1 city record set
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.
Origin: Augusta-Richmond County, GA-SC
53.4 µg/m³ peak ≈ 1.9 cigarettes per person 637k people affected 1 top-ten day
Supplied qualified evidence supports prescribed-fire smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
EPA AQS 1Agency/press 2
Origin: Houston-The Woodlands-Sugar Land, TX
47.4 µg/m³ peak ≈ 1.6 cigarettes per person 7.8M people affected 1 top-ten day
Supplied qualified evidence supports dust as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Agency/press 2
Origin: Phoenix-Mesa-Scottsdale, AZ; Tucson, AZ
131.9 µg/m³ peak ≈ 6.6 cigarettes per person 6.3M people affected 1 top-ten day
The supplied evidence supports a mixed episode in which holiday fireworks and fireplace smoke accumulated under an inversion.
EPA AQS 1Agency/press 2
Origin: San Diego-Carlsbad, CA
93 µg/m³ peak ≈ 14.6 cigarettes per person 3.3M people affected 1 top-ten day
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.
EPA AQS 4Agency/press 1
Origin: Fresno, CA
131.6 µg/m³ peak ≈ 10.1 cigarettes per person 1.2M people affected
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.
EPA AQS 4Agency/press 1
Named source Glass Fire · San Francisco-Oakland-Hayward, CA; San Jose-Sunnyvale-Santa Clara, CA; Stockton-Lodi, CA
103.9 µg/m³ peak ≈ 6.2 cigarettes per person 7.5M people affected
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.
EPA AQS 7Agency/press 2
Origin: Colorado Springs, CO; Denver-Aurora-Lakewood, CO
46.9 µg/m³ peak ≈ 1.8 cigarettes per person 3.8M people affected
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.
EPA AQS 1NWS alert 2Agency/press 2
Origin: Boise City, ID
61.6 µg/m³ peak ≈ 12.1 cigarettes per person 846k people affected 1 top-ten day
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.
EPA AQS 10Agency/press 2
Origin: Fresno, CA; Los Angeles-Long Beach-Anaheim, CA; Oxnard-Thousand Oaks-Ventura, CA; Sacramento--Roseville--Arden-Arcade, CA; San Diego-Carlsbad, CA; San Francisco-Oakland-Hayward, CA; San Jose-Sunnyvale-Santa Clara, CA; Stockton-Lodi, CA
199.3 µg/m³ peak ≈ 13.8 cigarettes per person 28M people affected 1 city record set, 8 top-ten days
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.
EPA AQS 67NWS alert 1Agency/press 4
Origin: Portland-Vancouver-Hillsboro, OR-WA; Seattle-Tacoma-Bellevue, WA; Spokane-Spokane Valley, WA
513.4 µg/m³ peak ≈ 68.9 cigarettes per person 7.3M people affected 2 city records set, 3 top-ten days
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.
EPA AQS 23NWS alert 2Agency/press 3
Origin: Bakersfield, CA
125.4 µg/m³ peak ≈ 5.1 cigarettes per person 923k people affected 1 top-ten day
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.
EPA AQS 2Agency/press 2
Origin: Las Vegas-Henderson-Paradise, NV
49.8 µg/m³ peak ≈ 1.9 cigarettes per person 2.4M people affected 1 top-ten day
Supplied qualified evidence supports multiple material causes for this event: wildfire-smoke and dust.
EPA AQS 1Agency/press 2
Named source Cameron Peak Fire · Colorado Springs, CO; Denver-Aurora-Lakewood, CO
49.7 µg/m³ peak ≈ 1.7 cigarettes per person 3.8M people affected
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/press 2
Named source Cameron Peak Fire · Colorado Springs, CO; Denver-Aurora-Lakewood, CO
51.6 µg/m³ peak ≈ 3.5 cigarettes per person 3.8M people affected
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.
NWS alert 1Agency/press 2
Origin: Ogden-Clearfield, UT; Salt Lake City, UT
71.5 µg/m³ peak ≈ 2.8 cigarettes per person 2.0M people affected
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.
EPA AQS 3Agency/press 2
Origin: Bakersfield, CA; Fresno, CA; Sacramento--Roseville--Arden-Arcade, CA; San Francisco-Oakland-Hayward, CA; San Jose-Sunnyvale-Santa Clara, CA; Stockton-Lodi, CA
158.6 µg/m³ peak ≈ 11.4 cigarettes per person 12M people affected 1 city record set, 3 top-ten days
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.
EPA AQS 38Agency/press 3
Origin: Buffalo-Cheektowaga-Niagara Falls, NY; Cleveland-Elyria, OH
61.8 µg/m³ peak ≈ 2.2 cigarettes per person 3.3M people affected 2 top-ten days
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Memphis, TN-MS-AR
57.9 µg/m³ peak ≈ 2.2 cigarettes per person 1.3M people affected 1 city record set
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Washington-Arlington-Alexandria, DC-VA-MD-WV
62.2 µg/m³ peak ≈ 2.3 cigarettes per person 6.4M people affected 1 top-ten day
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
EPA AQS 1Agency/press 2
Origin: Minneapolis-St. Paul-Bloomington, MN-WI
72.6 µg/m³ peak ≈ 2.9 cigarettes per person 3.8M people affected 1 top-ten day
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
EPA AQS 1Agency/press 1
Origin: St. Louis, MO-IL
62.5 µg/m³ peak ≈ 4.0 cigarettes per person 2.8M people affected 1 top-ten day
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Los Angeles-Long Beach-Anaheim, CA
175 µg/m³ peak ≈ 10.7 cigarettes per person 13M people affected 1 city record set
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
EPA AQS 2Agency/press 2
Origin: Miami-Fort Lauderdale-West Palm Beach, FL
45.2 µg/m³ peak ≈ 1.7 cigarettes per person 6.5M people affected
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Chattanooga, TN-GA; Des Moines-West Des Moines, IA; Greenville-Anderson-Mauldin, SC; Kansas City, MO-KS; Omaha-Council Bluffs, NE-IA; Wichita, KS
123.5 µg/m³ peak ≈ 3.7 cigarettes per person 6.3M people affected 1 city record set, 4 top-ten days
Supplied qualified evidence supports fireworks 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 fireworks 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 fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
EPA AQS 10Agency/press 2News 1
Origin: Austin-Round Rock, TX; Charleston-North Charleston, SC; Columbia, SC; Dallas-Fort Worth-Arlington, TX; Houston-The Woodlands-Sugar Land, TX; Jackson, MS; Little Rock-North Little Rock-Conway, AR; McAllen-Edinburg-Mission, TX; Nashville-Davidson--Murfreesboro--Franklin, TN; Oklahoma City, OK; Sahara Desert; San Antonio-New Braunfels, TX; Tulsa, OK; Wichita, KS
64.9 µg/m³ peak ≈ 2.0 cigarettes per person 31M people affected 2 city records set, 9 top-ten days
Supplied qualified evidence supports dust 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 dust 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 dust 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 dust 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 dust as the root ca
EPA AQS 10NWS alert 2Agency/press 5News 2
Cited: Saharan dust plume
Origin: Albuquerque, NM
35.1 µg/m³ peak ≈ 1.3 cigarettes per person 926k people affected
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.
NWS alert 1News 1
Origin: Wichita, KS
40.5 µg/m³ peak ≈ 1.5 cigarettes per person 661k people affected
Supplied qualified evidence supports prescribed-fire smoke as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Tampa-St. Petersburg-Clearwater, FL
38.4 µg/m³ peak ≈ 1.3 cigarettes per person 3.4M people affected
Supplied qualified evidence supports fireworks as the root cause. The grouping includes only events linked by explicit shared episode evidence; otherwise this remains a single-event episode.
Origin: Phoenix-Mesa-Scottsdale, AZ
149.1 µg/m³ peak ≈ 6.2 cigarettes per person 5.2M people affected 1 top-ten day
The supplied local and ADEQ evidence supports a mixed New Year's episode involving residential fireplace and fire-pit smoke together with fireworks.
Origin: Denver metropolitan area, Colorado
58.6 µg/m³ peak ≈ 2.0 cigarettes per person 3.8M people affected 1 top-ten day
State-agency meteorological attribution reported by Colorado Public Radio identifies a strong inversion that trapped local emissions in the Denver metro area; a National Park Service evaluation independently documents elevated PM2.5 during the same early-March period.
Agency/press 2
Origin: Austin-Round Rock-Georgetown metropolitan area, Texas
90.8 µg/m³ peak ≈ 3.0 cigarettes per person 10M people affected 2 top-ten days
The official regional assessment says the Austin-area January 1 PM2.5 day was most likely due to New Year's Eve fireworks.
Agency/press 1
Named source Camp Fire
228.4 µg/m³ peak ≈ 46.3 cigarettes per person 9.9M people affected 3 city records set, 4 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode and supports grouping 2 overlapping event records. Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode and supports grouping 2 overlapping event records.
EPA AQS 50Agency/press 3
Named source Dollar Ridge Fire, Bald Mountain Fire, Pole Creek Fire
76.2 µg/m³ peak ≈ 3.1 cigarettes per person 761k people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
Named source Pole Creek Fire, Bald Mountain Fire, Dollar Ridge Fire
74.5 µg/m³ peak ≈ 3.1 cigarettes per person 761k people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
105.3 µg/m³ peak ≈ 12.8 cigarettes per person 4.1M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 3NWS alert 1Agency/press 2
55.4 µg/m³ peak ≈ 2.4 cigarettes per person 3.8M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
185 µg/m³ peak ≈ 14.6 cigarettes per person 605k people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 2NWS alert 1Agency/press 1
95.9 µg/m³ peak ≈ 4.0 cigarettes per person 4.1M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 2
49.6 µg/m³ peak ≈ 1.9 cigarettes per person 2.4M people affected
Qualified frozen evidence supports mixed as the broad cause for this time-bounded episode.
EPA AQS 2News 1
56.9 µg/m³ peak ≈ 3.5 cigarettes per person 11M people affected 1 top-ten day
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
63.5 µg/m³ peak ≈ 2.3 cigarettes per person 5.2M people affected
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
65.8 µg/m³ peak ≈ 2.4 cigarettes per person 2.2M people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
49.7 µg/m³ peak ≈ 3.1 cigarettes per person 11M people affected 1 top-ten day
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
EPA AQS 2Agency/press 1
37.4 µg/m³ peak ≈ 1.4 cigarettes per person 861k people affected 1 top-ten day
Qualified frozen evidence supports other as the broad cause for this time-bounded episode.
Agency/press 1
43.8 µg/m³ peak ≈ 1.6 cigarettes per person 1.5M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
111 µg/m³ peak ≈ 4.1 cigarettes per person 19M people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode and supports grouping 2 overlapping event records.
EPA AQS 5Agency/press 1
134.1 µg/m³ peak ≈ 7.4 cigarettes per person 6.3M people affected 2 top-ten days
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
89.9 µg/m³ peak ≈ 3.4 cigarettes per person 13M people affected
Qualified frozen evidence supports mixed as the broad cause for this time-bounded episode.
86.6 µg/m³ peak ≈ 3.4 cigarettes per person 5.2M people affected
Qualified frozen evidence supports residential combustion as the broad cause for this time-bounded episode.
Named source Thomas Fire
100.7 µg/m³ peak ≈ 7.2 cigarettes per person 835k people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 2 records into the same time-bounded occurrence. Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 2 records into the same time-bounded occurrence.
EPA AQS 3Agency/press 4
Cited: CAL FIRE
89.4 µg/m³ peak ≈ 3.6 cigarettes per person 4.6M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
82.6 µg/m³ peak ≈ 3.4 cigarettes per person 846k people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 2Agency/press 2
70.3 µg/m³ peak ≈ 3.8 cigarettes per person 6.7M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 4NWS alert 1Agency/press 2
62.3 µg/m³ peak ≈ 2.3 cigarettes per person 3.8M people affected 2 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
194.9 µg/m³ peak ≈ 35.5 cigarettes per person 605k people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 5NWS alert 1Agency/press 1
68.5 µg/m³ peak ≈ 2.5 cigarettes per person 6.7M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
46.6 µg/m³ peak ≈ 1.7 cigarettes per person 2.4M people affected
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
127.3 µg/m³ peak ≈ 3.8 cigarettes per person 14M people affected 5 city records set, 8 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 5 records into the same time-bounded occurrence. Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 5 records into the same time-bounded occurrence. Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 5 records into the same time-bounded occurrence. Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 5 records into the same time-bounded occurrence. Qualified frozen evidence supports wildfire smoke as the broad cause and supports grouping 5 records into the same time-bounded occurrence.
EPA AQS 23NWS alert 1Agency/press 6
69.9 µg/m³ peak ≈ 2.8 cigarettes per person 2.4M people affected 1 top-ten day
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
43 µg/m³ peak ≈ 1.5 cigarettes per person 1.8M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
56.2 µg/m³ peak ≈ 2.1 cigarettes per person 3.8M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
45.8 µg/m³ peak ≈ 1.7 cigarettes per person 1.0M people affected
Qualified frozen evidence supports prescribed fire smoke as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 2
109.8 µg/m³ peak ≈ 4.6 cigarettes per person 2.5M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
66.7 µg/m³ peak ≈ 5.0 cigarettes per person 2.5M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
EPA AQS 2Agency/press 1
41.9 µg/m³ peak ≈ 1.4 cigarettes per person 2.3M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
49.4 µg/m³ peak ≈ 1.8 cigarettes per person 702k people affected
Qualified frozen evidence supports mixed as the broad cause for this time-bounded episode.
EPA AQS 2Agency/press 1
117.8 µg/m³ peak ≈ 3.7 cigarettes per person 21M people affected 4 top-ten days
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode and supports grouping 4 overlapping event records. Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode and supports grouping 4 overlapping event records. Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode and supports grouping 4 overlapping event records. Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode and supports grouping 4 overlapping event records.
EPA AQS 13Agency/press 3
40.9 µg/m³ peak ≈ 1.5 cigarettes per person 870k people affected
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
29.8 µg/m³ peak ≈ 1.1 cigarettes per person 1.1M people affected 1 top-ten day
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
62.3 µg/m³ peak ≈ 2.2 cigarettes per person 11M people affected
Qualified frozen evidence supports fireworks as the broad cause and supports grouping 2 records into the same time-bounded occurrence. Qualified frozen evidence supports fireworks as the broad cause and supports grouping 2 records into the same time-bounded occurrence.
EPA AQS 3Agency/press 2
43 µg/m³ peak ≈ 1.4 cigarettes per person 7.8M people affected
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
44.6 µg/m³ peak ≈ 1.6 cigarettes per person 6.5M people affected
Qualified frozen evidence supports wildfire smoke as the broad cause for this time-bounded episode.
Agency/press 2
50.6 µg/m³ peak ≈ 1.9 cigarettes per person 661k people affected 1 top-ten day
Qualified frozen evidence supports prescribed fire smoke as the broad cause for this time-bounded episode.
101.7 µg/m³ peak ≈ 4.1 cigarettes per person 5.2M people affected 1 top-ten day
Qualified frozen evidence supports mixed as the broad cause for this time-bounded episode.
Agency/press 1state-local-official-archive-discovery-v1 1
68.2 µg/m³ peak ≈ 4.1 cigarettes per person 2.4M people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
114.9 µg/m³ peak ≈ 8.9 cigarettes per person 923k people affected 1 top-ten day
Qualified frozen evidence supports other as the broad cause for this time-bounded episode.
76.9 µg/m³ peak ≈ 3.2 cigarettes per person 668k people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
EPA AQS 2Agency/press 1
78.6 µg/m³ peak ≈ 3.1 cigarettes per person 879k people affected
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
EPA AQS 1Agency/press 1
75.5 µg/m³ peak ≈ 3.0 cigarettes per person 879k people affected
Qualified frozen evidence supports dust as the broad cause for this time-bounded episode.
83.3 µg/m³ peak ≈ 3.4 cigarettes per person 2.5M people affected
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2012-07-12 PM2.5 episode affecting Sacramento--Roseville--Arden-Arcade, CA.
63.7 µg/m³ peak ≈ 2.6 cigarettes per person 668k people affected
Utah DEQ and the official monitor qualifier directly attribute the July 4 Ogden PM2.5 episode to fireworks emissions; the supplied reporting corroborates the post-fireworks spike.
EPA AQS 1Agency/press 2
Named source County Line Fire · Northern Florida
82.8 µg/m³ peak ≈ 6.4 cigarettes per person 1.8M people affected 1 top-ten day
The supplied official assessment attributes unhealthy particulate matter around Jacksonville during April 9-11 to County Line Fire smoke, with incident meteorology corroborating dense smoke during the period.
Agency/press 2
77.2 µg/m³ peak ≈ 2.9 cigarettes per person 9.4M people affected 1 top-ten day
Qualified frozen evidence supports prescribed-fire-smoke as the broad root cause of the 2012-03-27 PM2.5 episode affecting Chicago-Naperville-Elgin, IL-IN-WI.
Origin: Northern Mexico
130.4 µg/m³ peak ≈ 5.5 cigarettes per person 879k people affected 1 top-ten day
Official exceptional-event assessments consistently attribute the March 18 El Paso PM2.5 episode to a high-wind blowing-dust occurrence originating in northern Mexico.
EPA AQS 1Agency/press 2
85 µg/m³ peak ≈ 3.4 cigarettes per person 879k people affected
Qualified frozen evidence supports windblown-dust as the broad root cause of the 2012-03-07 PM2.5 episode affecting El Paso, TX.
EPA AQS 1Agency/press 1
48.9 µg/m³ peak ≈ 1.8 cigarettes per person 870k people affected 1 top-ten day
Qualified frozen evidence supports prescribed-fire-smoke as the broad root cause of the 2012-01-16 PM2.5 episode affecting Charleston-North Charleston, SC.
61.2 µg/m³ peak ≈ 2.4 cigarettes per person 2.4M people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause of the 2012-01-01 PM2.5 episode affecting Las Vegas-Henderson-Paradise, NV.
45.9 µg/m³ peak ≈ 2.9 cigarettes per person 883k people affected
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2011-08-30 through 2011-08-31 PM2.5 episode affecting Baton Rouge, LA.
EPA AQS 2
41.7 µg/m³ peak ≈ 1.5 cigarettes per person 1.8M people affected
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2011-08-25 PM2.5 episode affecting Virginia Beach-Norfolk-Newport News, VA-NC.
Named source Great Dismal Swamp wildfire · Great Dismal Swamp, Virginia and North Carolina
52.9 µg/m³ peak ≈ 2.0 cigarettes per person 1.8M people affected
The Virginia DEQ alert and supporting frozen records attribute the August 19 Hampton Roads fine-particle episode to smoke from the Great Dismal Swamp wildfire.
EPA AQS 1NWS alert 1Agency/press 1
Cited: Virginia Department of Environmental Quality
102.3 µg/m³ peak ≈ 4.1 cigarettes per person 5.2M people affected 1 top-ten day
National Weather Service, ADEQ, and monitor-qualifier evidence consistently support windblown dust as the broad cause of the July 5 Phoenix PM2.5 episode.
Named source Honey Prairie Fire · Southeastern Georgia
42.6 µg/m³ peak ≈ 4.4 cigarettes per person 870k people affected
Official monitor qualifiers support wildfire smoke on June 21-23, and the supplied satellite analysis documents Honey Prairie Fire smoke transport and recirculation in the Charleston plume environment.
EPA AQS 3Agency/press 1
47.5 µg/m³ peak ≈ 1.8 cigarettes per person 870k people affected 1 top-ten day
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2011-06-18 PM2.5 episode affecting Charleston-North Charleston, SC.
39.7 µg/m³ peak ≈ 1.5 cigarettes per person 926k people affected
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2011-06-08 PM2.5 episode affecting Albuquerque, NM.
Named source Wallow Fire, Horseshoe Fire · Arizona
53.3 µg/m³ peak ≈ 5.4 cigarettes per person 926k people affected 1 top-ten day
Official monitor qualifiers and contemporaneous transport evidence support wildfire smoke throughout the June 2-4 Albuquerque episode; the supplied meteorological account identifies smoke transported from Arizona's Wallow and Horseshoe fires.
EPA AQS 5Agency/press 1
53.3 µg/m³ peak ≈ 3.5 cigarettes per person 997k people affected 1 top-ten day
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2011-06-01 through 2011-06-02 PM2.5 episode affecting Greenville-Anderson-Mauldin, SC.
64.6 µg/m³ peak ≈ 4.9 cigarettes per person 668k people affected
Qualified frozen evidence supports winter-inversion as the broad root cause of the 2011-01-06 through 2011-01-07 PM2.5 episode affecting Ogden-Clearfield, UT.
30 µg/m³ peak ≈ 1.2 cigarettes per person 999k people affected
Qualified frozen evidence supports fireworks as the broad root cause of the 2010-12-31 PM2.5 episode affecting Urban Honolulu, HI.
57.5 µg/m³ peak ≈ 2.8 cigarettes per person 2.3M people affected 1 top-ten day
The frozen records support a December 31-January 1 Connecticut River Valley particle-pollution episode, and the contemporaneous alert attributes the Springfield portion to inversion or stagnant conditions trapping pollution. This supports winter inversion as the broad cause, while Allentown remains unassessed.
NWS alert 1Agency/press 1
41.9 µg/m³ peak ≈ 1.5 cigarettes per person 2.4M people affected
Qualified frozen evidence supports fireworks as the broad root cause of the 2010-07-04 PM2.5 episode affecting Las Vegas-Henderson-Paradise, NV.
40.5 µg/m³ peak ≈ 1.4 cigarettes per person 997k people affected
Qualified frozen evidence supports fireworks as the broad root cause of the 2010-07-04 PM2.5 episode affecting Greenville-Anderson-Mauldin, SC.
44.6 µg/m³ peak ≈ 1.6 cigarettes per person 1.0M people affected
Qualified frozen evidence supports fireworks as the broad root cause of the 2010-07-04 PM2.5 episode affecting Omaha-Council Bluffs, NE-IA.
Origin: Canada
60.5 µg/m³ peak ≈ 2.3 cigarettes per person 5.0M people affected 1 top-ten day
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2010-05-31 PM2.5 episode affecting Boston-Cambridge-Newton, MA-NH.
EPA AQS 2
107.8 µg/m³ peak ≈ 4.3 cigarettes per person 923k people affected
Qualified frozen evidence supports windblown-dust as the broad root cause of the 2010-04-11 PM2.5 episode affecting Bakersfield, CA.
EPA AQS 2Agency/press 1
41.1 µg/m³ peak ≈ 1.5 cigarettes per person 1.2M people affected
Qualified frozen evidence supports wildfire-smoke as the broad root cause of the 2010-03-09 PM2.5 episode affecting Buffalo-Cheektowaga-Niagara Falls, NY.
27.6 µg/m³ peak ≈ 1.0 cigarettes per person 999k people affected
Qualified frozen evidence supports fireworks as the broad root cause of the 2010-01-01 PM2.5 episode affecting Urban Honolulu, HI.
43.4 µg/m³ peak ≈ 1.5 cigarettes per person 966k people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause of the 2009-12-31 PM2.5 episode affecting New Orleans-Metairie, LA.
Origin: Wasatch Front, Utah
80.4 µg/m³ peak ≈ 6.6 cigarettes per person 2.7M people affected
Both supplied scientific corroboration records support a contemporaneous January 2009 Wasatch Front winter-inversion episode, and their affected intervals overlap across January 21-22. Both supplied scientific corroboration records support a contemporaneous January 2009 Wasatch Front winter-inversion episode, and their affected intervals overlap across January 21-22.
Agency/press 1
78.3 µg/m³ peak ≈ 3.0 cigarettes per person 3.3M people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause of the 2009-01-01 PM2.5 episode affecting San Diego-Carlsbad, CA.
78.3 µg/m³ peak ≈ 2.9 cigarettes per person 13M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
70.7 µg/m³ peak ≈ 2.8 cigarettes per person 1.8M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad root cause.
EPA AQS 1Agency/press 1
84.9 µg/m³ peak ≈ 5.6 cigarettes per person 1.8M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad root cause.
EPA AQS 2Agency/press 2
81.2 µg/m³ peak ≈ 3.2 cigarettes per person 816k people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
EPA AQS 1Agency/press 1
Named source South One Fire, Evans Road Fire · eastern North Carolina; southeastern Virginia
99 µg/m³ peak ≈ 4.3 cigarettes per person 12M people affected 3 city records set, 5 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bo
EPA AQS 13Agency/press 5
48.9 µg/m³ peak ≈ 1.8 cigarettes per person 1.4M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad root cause.
29.5 µg/m³ peak ≈ 1.1 cigarettes per person 999k people affected
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
Origin: Minnesota Twin Cities region
53.7 µg/m³ peak ≈ 2.0 cigarettes per person 3.8M people affected
Reporting on the MPCA alert attributes elevated fine particles affecting the Twin Cities to a large regional inversion trapping contaminated air.
Origin: Southern California
126.2 µg/m³ peak ≈ 13.2 cigarettes per person 3.3M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad root cause; the Witch Creek and Guejito fires are retained as specific contributing sources rather than used as the grouping key.
EPA AQS 3Agency/press 3
Cited: City of San Diego
35.3 µg/m³ peak ≈ 1.3 cigarettes per person 740k people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
51.2 µg/m³ peak ≈ 3.5 cigarettes per person 1.5M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 3
Origin: Idaho, Montana, and Canada
46.4 µg/m³ peak ≈ 1.6 cigarettes per person 2.9M people affected 1 top-ten day
North Carolina DEQ identifies Idaho, Montana, and Canadian wildfire impacts at Greensboro's Mendenhall monitor on August 5.
EPA AQS 1Agency/press 1
51.3 µg/m³ peak ≈ 1.8 cigarettes per person 1.4M people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
50.2 µg/m³ peak ≈ 3.2 cigarettes per person 3.5M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 4
46.6 µg/m³ peak ≈ 1.6 cigarettes per person 2.2M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
Origin: Salt Lake City, Utah
78.2 µg/m³ peak ≈ 3.2 cigarettes per person 1.3M people affected
EPA identifies this Salt Lake City July 4 PM2.5 event as a fireworks exceptional event.
Agency/press 1
50.8 µg/m³ peak ≈ 1.9 cigarettes per person 1.2M people affected 1 top-ten day
Qualified frozen causal evidence supports fireworks as the broad root cause.
59.2 µg/m³ peak ≈ 4.1 cigarettes per person 6.5M people affected 1 top-ten day
Qualified frozen causal evidence supports multiple material causes for this episode: fireworks and wildfire smoke.
EPA AQS 3
45 µg/m³ peak ≈ 1.6 cigarettes per person 1.6M people affected 1 top-ten day
Qualified frozen causal evidence supports prescribed fire smoke as the broad root cause.
38.1 µg/m³ peak ≈ 1.2 cigarettes per person 769k people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
50.4 µg/m³ peak ≈ 4.8 cigarettes per person 1.3M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 3
26.2 µg/m³ peak ≈ 0.9 cigarettes per person 935k people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
71.5 µg/m³ peak ≈ 2.9 cigarettes per person 870k people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
87.9 µg/m³ peak ≈ 3.8 cigarettes per person 2.5M people affected 1 city record set, 2 top-ten days
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 3Agency/press 2
Origin: Ware County, Georgia and northern Florida
137.3 µg/m³ peak ≈ 6.6 cigarettes per person 29M people affected 4 city records set, 9 top-ten days
Supporting records describe regional smoke transport from Georgia-Florida fires, with the official Georgia assessment identifying Ware County and northern Florida fires as contributors during this May-to-early-June episode. Supporting records describe regional smoke transport from Georgia-Florida fires, with the official Georgia assessment identifying Ware County and northern Florida fires as contributors during this May-to-early-June episode. Supporting records describe regional smoke transport from Georgia-Florida fires, with the official Georgia assessment identifying Ware County and northern Florida fires as contributors during this May-to-early-June episode. Supporting records describe regional smoke transport from Georgia-Florida fires, with the official Georgia assessment identifyin
EPA AQS 33Agency/press 8
53.9 µg/m³ peak ≈ 3.7 cigarettes per person 6.5M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
39.2 µg/m³ peak ≈ 1.3 cigarettes per person 870k people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
48.9 µg/m³ peak ≈ 1.7 cigarettes per person 2.5M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
35.8 µg/m³ peak ≈ 1.1 cigarettes per person 4.7M people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 3
39.4 µg/m³ peak ≈ 1.4 cigarettes per person 1.8M people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 1Agency/press 1
65.5 µg/m³ peak ≈ 4.9 cigarettes per person 1.8M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
24 µg/m³ peak ≈ 0.8 cigarettes per person 740k people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
71.6 µg/m³ peak ≈ 2.9 cigarettes per person 4.1M people affected
Qualified frozen causal evidence supports residential combustion as the broad root cause.
51.1 µg/m³ peak ≈ 2.1 cigarettes per person 999k people affected
Qualified frozen evidence supports fireworks as the broad root cause.
EPA AQS 1Agency/press 1
68.3 µg/m³ peak ≈ 2.7 cigarettes per person 4.1M people affected
Qualified frozen evidence supports residential combustion as the broad root cause.
41.4 µg/m³ peak ≈ 1.5 cigarettes per person 966k people affected
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
44.2 µg/m³ peak ≈ 1.4 cigarettes per person 7.8M people affected
Qualified frozen evidence supports transported or windblown dust as the broad root cause.
48.9 µg/m³ peak ≈ 1.7 cigarettes per person 1.4M people affected
Qualified frozen evidence supports fireworks as the broad root cause.
75.8 µg/m³ peak ≈ 2.9 cigarettes per person 6.4M people affected 1 top-ten day
Qualified frozen evidence supports prescribed-fire smoke as the broad root cause.
49.2 µg/m³ peak ≈ 1.8 cigarettes per person 588k people affected
Qualified frozen evidence supports multiple material contributors to this event: wildfire smoke and fireworks.
38.9 µg/m³ peak ≈ 1.2 cigarettes per person 7.8M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
34.7 µg/m³ peak ≈ 0.9 cigarettes per person 2.4M people affected 1 top-ten day
Qualified frozen evidence supports wildfire smoke as the broad root cause.
88.1 µg/m³ peak ≈ 3.8 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause.
EPA AQS 1Agency/press 1
59.2 µg/m³ peak ≈ 2.3 cigarettes per person 966k people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
40.5 µg/m³ peak ≈ 1.3 cigarettes per person 3.8M people affected
Qualified frozen evidence supports prescribed-fire smoke as the broad root cause.
EPA AQS 2
44.8 µg/m³ peak ≈ 1.6 cigarettes per person 966k people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
46.8 µg/m³ peak ≈ 5.4 cigarettes per person 10M people affected 5 top-ten days
Qualified frozen evidence supports transported or windblown dust as the broad root cause.
EPA AQS 3
Origin: Idaho and Montana
58.9 µg/m³ peak ≈ 3.6 cigarettes per person 11M people affected 3 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bo
EPA AQS 3Agency/press 4
39 µg/m³ peak ≈ 1.4 cigarettes per person 801k people affected
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
30.9 µg/m³ peak ≈ 1.1 cigarettes per person 853k people affected 1 top-ten day
Qualified frozen evidence supports transported or windblown dust as the broad root cause.
79.8 µg/m³ peak ≈ 2.9 cigarettes per person 4.7M people affected
Qualified frozen evidence supports fireworks as the broad root cause.
79.2 µg/m³ peak ≈ 2.3 cigarettes per person 11M people affected 2 top-ten days
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episo
Agency/press 1
81.6 µg/m³ peak ≈ 5.1 cigarettes per person 34M people affected 7 top-ten days
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episo
Agency/press 1
102.8 µg/m³ peak ≈ 6.7 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause.
EPA AQS 2Agency/press 2
Origin: Alaska
36.2 µg/m³ peak ≈ 1.1 cigarettes per person 6.6M people affected 2 top-ten days
Qualified frozen evidence supports multiple material contributors to this event: wildfire smoke and transported or windblown dust.
EPA AQS 4Agency/press 1
Origin: Alaska
56.4 µg/m³ peak ≈ 1.9 cigarettes per person 34M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bo
EPA AQS 4Agency/press 3
93.4 µg/m³ peak ≈ 2.9 cigarettes per person 18M people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause.
46.2 µg/m³ peak ≈ 1.5 cigarettes per person 7.8M people affected
Qualified frozen evidence supports transported or windblown dust as the broad root cause.
71.3 µg/m³ peak ≈ 2.6 cigarettes per person 2.4M people affected
Allegheny County Health Department directly reports that a nighttime temperature inversion accumulated very high PM2.5 at Liberty on June 8, 2004. This supports a standalone documented accumulation episode, while the underlying mixture of regional and local anthropogenic emissions remains unidentified.
state-local-official-archive-discovery-v2 1
82.1 µg/m³ peak ≈ 4.6 cigarettes per person 1.4M people affected 1 top-ten day
Qualified frozen evidence supports winter inversion as the broad root cause.
91.8 µg/m³ peak ≈ 4.0 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
239.2 µg/m³ peak ≈ 11.0 cigarettes per person 24M people affected 2 city records set, 4 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode.
EPA AQS 3Agency/press 2
63.4 µg/m³ peak ≈ 2.4 cigarettes per person 6.4M people affected 1 top-ten day
Qualified frozen evidence supports prescribed-fire smoke as the broad root cause.
39.3 µg/m³ peak ≈ 1.3 cigarettes per person 588k people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
46.9 µg/m³ peak ≈ 2.9 cigarettes per person 6.0M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode.
EPA AQS 4
57 µg/m³ peak ≈ 4.3 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
EPA AQS 2
62.7 µg/m³ peak ≈ 2.6 cigarettes per person 6.0M people affected 3 top-ten days
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
EPA AQS 4
57.5 µg/m³ peak ≈ 5.9 cigarettes per person 21M people affected 4 top-ten days
Qualified frozen evidence supports industrial emissions as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports industrial emissions as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports industrial emissions as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode.
Agency/press 2
49.8 µg/m³ peak ≈ 2.4 cigarettes per person 5.6M people affected 3 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad root cause.
EPA AQS 6
27.6 µg/m³ peak ≈ 1.0 cigarettes per person 1.1M people affected
Qualified frozen evidence supports transported or windblown dust as the broad root cause.
Origin: Quebec
118.4 µg/m³ peak ≈ 6.7 cigarettes per person 44M people affected 2 city records set, 15 top-ten days
Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bounded episode. Qualified frozen evidence supports wildfire smoke as the broad root cause and supports grouping the contemporaneous affected events into one time-bo
EPA AQS 34Agency/press 4
88.8 µg/m³ peak ≈ 5.9 cigarettes per person 2.8M people affected 1 city record set
Qualified frozen evidence supports fireworks as the broad root cause.
37.4 µg/m³ peak ≈ 1.3 cigarettes per person 870k people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
100.2 µg/m³ peak ≈ 6.2 cigarettes per person 2.0M people affected 1 city record set, 2 top-ten days
Qualified frozen evidence supports winter inversion as the broad root cause.
Agency/press 1
87.3 µg/m³ peak ≈ 6.0 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen causal evidence supports other as the broad root cause.
EPA AQS 2Agency/press 2
78.1 µg/m³ peak ≈ 3.1 cigarettes per person 9.0M people affected 2 top-ten days
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 9
54.6 µg/m³ peak ≈ 1.9 cigarettes per person 20M people affected
Qualified frozen causal evidence supports other as the broad root cause.
Origin: Eastern Seaboard, United States
53.4 µg/m³ peak ≈ 2.1 cigarettes per person 11M people affected
The supplied study identifies an 8–9 August Eastern Seaboard pollution episode with extensive aerosol loading and frontal-system recirculation affecting the candidate’s region.
Agency/press 1
Named source 800-acre fire near Orlando · Orlando area, Florida
60.5 µg/m³ peak ≈ 3.8 cigarettes per person 4.7M people affected 2 top-ten days
Contemporaneous reporting identifies an 800-acre fire near Orlando beginning May 26 and says smoke covered Orlando on May 27.
EPA AQS 6Agency/press 1
82.9 µg/m³ peak ≈ 3.3 cigarettes per person 879k people affected
Qualified frozen causal evidence supports dust as the broad root cause.
Origin: Polk County, Florida
59.2 µg/m³ peak ≈ 1.7 cigarettes per person 4.7M people affected 3 top-ten days
The frozen baseline classifies this event as wildfire smoke, and the retained NOAA, Florida legislative, and scientific records consistently document the contemporaneous Polk City-Lakeland wildfire and smoke occurrence.
Agency/press 3
Origin: Maryland–Mid-Atlantic
70.5 µg/m³ peak ≈ 2.3 cigarettes per person 4.9M people affected
Maryland’s retrospective analysis identifies the 12–15 January episode, including Baltimore, with stagnation and a strong morning inversion, plus a nitrate-rich local component.
Origin: San Joaquin Valley, California
154.7 µg/m³ peak ≈ 6.7 cigarettes per person 1.8M people affected 1 top-ten day
CRPAQS explicitly identifies one major San Joaquin Valley episode during 4–7 January 2001, driven by particulate ammonium nitrate, and places both dates within it. CRPAQS explicitly identifies one major San Joaquin Valley episode during 4–7 January 2001, driven by particulate ammonium nitrate, and places both dates within it.
Agency/press 1
Origin: Oʻahu, Hawaii
130.1 µg/m³ peak ≈ 5.7 cigarettes per person 999k people affected 1 city record set
Contemporaneous reporting describes officials' assessment of fireworks use and related smoke during the December 31, 2000 Oʻahu celebration, supporting fireworks as the material source occurrence.
EPA AQS 1Agency/press 2
Origin: California Central Valley
112.7 µg/m³ peak ≈ 8.2 cigarettes per person 2.9M people affected
The modeling study specifically examines the Central Valley Christmas–New Year 2000–2001 episode, including December 31, and attributes the Bakersfield portion chiefly to secondary inorganic aerosol.
Agency/press 1
38.9 µg/m³ peak ≈ 1.3 cigarettes per person 1.4M people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
54.7 µg/m³ peak ≈ 1.9 cigarettes per person 7.1M people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
78.8 µg/m³ peak ≈ 4.9 cigarettes per person 8.0M people affected 3 top-ten days
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
EPA AQS 4
Origin: North Carolina and neighboring states
84.5 µg/m³ peak ≈ 4.3 cigarettes per person 8.6M people affected 2 city records set, 5 top-ten days
The North Carolina assessment attributes early-November particulate impacts, including November 2–4, to smoke from forest fires in North Carolina and neighboring states; both events fall within that assessed occurrence. The North Carolina assessment attributes early-November particulate impacts, including the Winston-Salem value and November 2–4 period, to smoke from forest fires in North Carolina and neighboring states.
48.2 µg/m³ peak ≈ 1.6 cigarettes per person 2.3M people affected
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
71.6 µg/m³ peak ≈ 3.8 cigarettes per person 1.8M people affected 2 top-ten days
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
57 µg/m³ peak ≈ 2.0 cigarettes per person 9.0M people affected 1 top-ten day
Qualified frozen causal evidence supports wildfire smoke as the broad root cause.
Origin: San Joaquin Valley, California
160 µg/m³ peak ≈ 8.5 cigarettes per person 2.1M people affected 1 top-ten day
District evidence identifies a valley-wide January 7–10 episode; the Fresno evidence independently describes the same January episode as accumulated local primary and secondary pollution under limited dispersion. District and measurement-study evidence identify the January 7–10/2–12 San Joaquin Valley winter episode, including the January 9 Fresno maximum and January 7 Bakersfield impacts.
Agency/press 2
105 µg/m³ peak ≈ 8.3 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen evidence supports fireworks as the broad root cause.
EPA AQS 2Agency/press 2
134.8 µg/m³ peak ≈ 9.2 cigarettes per person 2.1M people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
Agency/press 1
90 µg/m³ peak ≈ 3.3 cigarettes per person 4.5M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
157.1 µg/m³ peak ≈ 6.7 cigarettes per person 2.2M people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
108 µg/m³ peak ≈ 4.5 cigarettes per person 2.5M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
72.1 µg/m³ peak ≈ 2.8 cigarettes per person 6.4M people affected 1 top-ten day
Qualified frozen evidence supports prescribed-fire smoke as the broad root cause.
Named source Palm Beach County brush fire · Palm Beach County, Florida
46.9 µg/m³ peak ≈ 1.7 cigarettes per person 6.5M people affected
Qualified frozen evidence supports wildfire smoke as the broad root cause.
NOAA 1
73.1 µg/m³ peak ≈ 3.1 cigarettes per person 999k people affected 1 top-ten day
Qualified frozen evidence supports other documented PM source or accumulation mechanism as the broad root cause.
No episodes match. Clear the search or pick a different cause.
Multi-metro or extreme episodes the resolution pass has not yet attributed. Listing here is a coverage statement, not a causal claim: no result yet means unknown, not "no smoke" or "no dust". Showing the top 60 of 205 by peak.
| Dates | Metros | Peak PM2.5 | Peak near |
|---|---|---|---|
| Jan 1, 2016 | Phoenix-Mesa-Scottsdale, Tucson | 152.1 µg/m³ | Phoenix-Mesa-Scottsdale |
| Dec 25, 1999 | Bakersfield, San Jose-Sunnyvale-Santa Clara | 134.1 µg/m³ | Bakersfield |
| Dec 22 to Dec 25, 1999 | Fresno, Stockton-Lodi | 134 µg/m³ | Fresno |
| Jan 19 to Jan 25, 2013 | Provo-Orem, Ogden-Clearfield | 129.5 µg/m³ | Provo-Orem |
| Jan 15, 1999 | Fresno, Stockton-Lodi | 128 µg/m³ | Fresno |
| Nov 5, 1999 | Los Angeles-Long Beach-Anaheim, Oxnard-Thousand Oaks-Ventura, Riverside-San Bernardino-Ontario | 121.4 µg/m³ | Riverside-San Bernardino-Ontario |
| Oct 18 to Oct 20, 2000 | Los Angeles-Long Beach-Anaheim, Oxnard-Thousand Oaks-Ventura, Riverside-San Bernardino-Ontario | 119.6 µg/m³ | Riverside-San Bernardino-Ontario |
| Dec 17 to Dec 18, 1999 | Stockton-Lodi, Fresno | 119 µg/m³ | Fresno |
| Dec 20, 1999 | Fresno, Sacramento--Roseville--Arden-Arcade, Stockton-Lodi | 119 µg/m³ | Fresno |
| Dec 1 to Dec 3, 2000 | Los Angeles-Long Beach-Anaheim, Riverside-San Bernardino-Ontario, San Diego-Carlsbad | 113.9 µg/m³ | Los Angeles-Long Beach-Anaheim |
| Oct 21 to Oct 23, 2005 | Riverside-San Bernardino-Ontario, Oxnard-Thousand Oaks-Ventura | 106.2 µg/m³ | Riverside-San Bernardino-Ontario |
| Jul 4 to Jul 5, 2002 | Cincinnati, Indianapolis-Carmel-Anderson, Louisville/Jefferson County | 100.6 µg/m³ | Louisville/Jefferson County |
| May 2 to May 4, 2001 | Pittsburgh, Buffalo-Cheektowaga-Niagara Falls | 98.6 µg/m³ | Pittsburgh |
| Nov 3 to Nov 4, 2001 | Oxnard-Thousand Oaks-Ventura, Riverside-San Bernardino-Ontario | 98 µg/m³ | Riverside-San Bernardino-Ontario |
| Jan 18, 1999 | Los Angeles-Long Beach-Anaheim, Riverside-San Bernardino-Ontario | 97.9 µg/m³ | Riverside-San Bernardino-Ontario |
| Jan 6 to Jan 9, 2013 | Provo-Orem, Ogden-Clearfield, Salt Lake City | 95.2 µg/m³ | Provo-Orem |
| Nov 6 to Nov 7, 2001 | Los Angeles-Long Beach-Anaheim, Riverside-San Bernardino-Ontario | 94.7 µg/m³ | Los Angeles-Long Beach-Anaheim |
| Feb 15 to Feb 16, 2004 | Ogden-Clearfield, Salt Lake City, Provo-Orem | 94.2 µg/m³ | Salt Lake City |
| Mar 19, 2004 | Oxnard-Thousand Oaks-Ventura, Riverside-San Bernardino-Ontario | 93.8 µg/m³ | Riverside-San Bernardino-Ontario |
| Oct 20 to Oct 21, 2000 | Los Angeles-Long Beach-Anaheim, Oxnard-Thousand Oaks-Ventura | 92.5 µg/m³ | Los Angeles-Long Beach-Anaheim |
| Nov 30, 2002 | Sacramento--Roseville--Arden-Arcade, San Francisco-Oakland-Hayward | 91 µg/m³ | Sacramento--Roseville--Arden-Arcade |
| Jan 26 to Jan 30, 2007 | Salt Lake City, Ogden-Clearfield, Provo-Orem | 86.6 µg/m³ | Salt Lake City |
| Jul 17 to Jul 18, 2001 | Atlanta-Sandy Springs-Roswell, Knoxville, Chattanooga, Greenville-Anderson-Mauldin | 86.5 µg/m³ | Knoxville |
| Jan 21, 2001 | San Francisco-Oakland-Hayward, San Jose-Sunnyvale-Santa Clara | 85.6 µg/m³ | San Jose-Sunnyvale-Santa Clara |
| Jun 24 to Jun 26, 2003 | Pittsburgh, Akron, Columbus | 85.2 µg/m³ | Pittsburgh |
| Sep 13 to Sep 14, 2005 | Akron, Buffalo-Cheektowaga-Niagara Falls, Pittsburgh | 84.9 µg/m³ | Pittsburgh |
| Dec 23 to Dec 24, 2000 | Los Angeles-Long Beach-Anaheim, Oxnard-Thousand Oaks-Ventura, Riverside-San Bernardino-Ontario, San Diego-Carlsbad | 84.5 µg/m³ | Riverside-San Bernardino-Ontario |
| Dec 30 to Dec 31, 2001 | Ogden-Clearfield, Provo-Orem, Salt Lake City | 83 µg/m³ | Provo-Orem |
| Jan 24, 2004 | Provo-Orem, Salt Lake City | 82 µg/m³ | Provo-Orem |
| Dec 27 to Dec 29, 2001 | Ogden-Clearfield, Provo-Orem, Salt Lake City | 80.8 µg/m³ | Salt Lake City |
| Jan 1, 2001 | San Francisco-Oakland-Hayward, San Jose-Sunnyvale-Santa Clara | 80 µg/m³ | San Jose-Sunnyvale-Santa Clara |
| Feb 9 to Feb 10, 2000 | Pittsburgh, Cleveland-Elyria | 78.5 µg/m³ | Pittsburgh |
| Jul 1 to Jul 2, 2002 | Boston-Cambridge-Newton, Springfield, New Haven-Milford, Worcester | 78.4 µg/m³ | Springfield |
| Oct 26 to Oct 27, 2000 | Baltimore-Columbia-Towson, New York-Newark-Jersey City | 77.7 µg/m³ | New York-Newark-Jersey City |
| Jan 19 to Jan 20, 2004 | Ogden-Clearfield, Provo-Orem | 77.5 µg/m³ | Provo-Orem |
| Jan 1, 2001 | Los Angeles-Long Beach-Anaheim, San Diego-Carlsbad | 77.3 µg/m³ | Los Angeles-Long Beach-Anaheim |
| Jan 29 to Jan 30, 2007 | Provo-Orem, Ogden-Clearfield | 76.8 µg/m³ | Ogden-Clearfield |
| Jan 11 to Jan 13, 2010 | Ogden-Clearfield, Salt Lake City | 76.7 µg/m³ | Salt Lake City |
| Aug 7, 1999 | Augusta-Richmond County, Charlotte-Concord-Gastonia | 76.4 µg/m³ | Augusta-Richmond County |
| Oct 28 to Oct 30, 2000 | Jacksonville, Orlando-Kissimmee-Sanford, Tampa-St. Petersburg-Clearwater | 75.3 µg/m³ | Tampa-St. Petersburg-Clearwater |
| Dec 25, 2006 | San Francisco-Oakland-Hayward, San Jose-Sunnyvale-Santa Clara | 75.3 µg/m³ | San Francisco-Oakland-Hayward |
| Feb 1 to Feb 2, 2017 | Provo-Orem, Ogden-Clearfield | 75.3 µg/m³ | Provo-Orem |
| Oct 23 to Oct 27, 2000 | Birmingham-Hoover, Chattanooga | 75.2 µg/m³ | Birmingham-Hoover |
| Jun 11 to Jun 12, 2001 | Knoxville, Louisville/Jefferson County | 73.9 µg/m³ | Knoxville |
| Jan 23 to Jan 24, 2001 | Allentown-Bethlehem-Easton, Hartford-West Hartford-East Hartford, New York-Newark-Jersey City, Springfield | 73.5 µg/m³ | Allentown-Bethlehem-Easton |
| Jun 26, 2003 | Baltimore-Columbia-Towson, Harrisburg-Carlisle, Philadelphia-Camden-Wilmington, Washington-Arlington-Alexandria | 73.1 µg/m³ | Philadelphia-Camden-Wilmington |
| Jul 16 to Jul 17, 1999 | Akron, Buffalo-Cheektowaga-Niagara Falls, Pittsburgh | 72.8 µg/m³ | Pittsburgh |
| Mar 14 to Mar 15, 2025 | Dallas-Fort Worth-Arlington, Austin-Round Rock | 72.3 µg/m³ | Dallas-Fort Worth-Arlington |
| Jan 1, 2000 | Ogden-Clearfield, Salt Lake City | 71.3 µg/m³ | Salt Lake City |
| Feb 28 to Mar 1, 2003 | Detroit-Warren-Dearborn, Toledo, Cleveland-Elyria | 70.3 µg/m³ | Detroit-Warren-Dearborn |
| Aug 25, 1999 | Boston-Cambridge-Newton, Springfield | 70.1 µg/m³ | Boston-Cambridge-Newton |
| Aug 11 to Aug 12, 2002 | Cleveland-Elyria, Pittsburgh, Buffalo-Cheektowaga-Niagara Falls | 69.6 µg/m³ | Pittsburgh |
| Jul 4 to Jul 5, 2003 | Scranton--Wilkes-Barre--Hazleton, Bridgeport-Stamford-Norwalk, Hartford-West Hartford-East Hartford, New Haven-Milford | 69.6 µg/m³ | Scranton--Wilkes-Barre--Hazleton |
| Jun 26 to Jun 27, 2003 | Albany-Schenectady-Troy, Allentown-Bethlehem-Easton, Bridgeport-Stamford-Norwalk, Hartford-West Hartford-East Hartford +3 | 69.3 µg/m³ | Allentown-Bethlehem-Easton |
| Jul 27, 1999 | Atlanta-Sandy Springs-Roswell, Birmingham-Hoover | 67.9 µg/m³ | Atlanta-Sandy Springs-Roswell |
| Jul 4, 2002 | Lakeland-Winter Haven, Palm Bay-Melbourne-Titusville, Miami-Fort Lauderdale-West Palm Beach | 66.8 µg/m³ | Miami-Fort Lauderdale-West Palm Beach |
| Feb 10, 2000 | Allentown-Bethlehem-Easton, Baltimore-Columbia-Towson, Philadelphia-Camden-Wilmington | 66.6 µg/m³ | Baltimore-Columbia-Towson |
| Oct 21 to Oct 22, 2000 | Atlanta-Sandy Springs-Roswell, Greenville-Anderson-Mauldin | 66.6 µg/m³ | Atlanta-Sandy Springs-Roswell |
| Feb 4, 2000 | Baltimore-Columbia-Towson, Harrisburg-Carlisle | 65.9 µg/m³ | Harrisburg-Carlisle |
| Dec 11, 2002 | Detroit-Warren-Dearborn, Toledo | 65.8 µg/m³ | Detroit-Warren-Dearborn |
The gap. Plenty of institutions publish air-quality data, and they do it well. EPA's AQS holds the certified monitor record; AirNow shows what is happening now; NOAA forecasts what is coming; NWS issues alerts while it happens; Storm Events writes it down afterwards. What none of them publishes is the middle layer: a named, durable event that says these metros, on these days, were one occurrence, and here is what the evidence says caused it. Monitor records are organized by station and date. News coverage is organized by the day it was written and disappears behind the next cycle. So the obvious question after a bad week, "what was that, how bad was it here, and has it happened before," has no single place to land.
What we are trying to do. Assemble those scattered records into events that persist: named, dated, with the affected metros, each metro's own numbers, a cause where the evidence supports one, and every source kept as a link. The aim is a reference that is still useful years later and can be cited by a reporter in five minutes, not a recap that ages out in a week. When the data are revised, the record gets revised with them.
How it maps to existing sources. We are not replacing any of them, and we do not run our own attribution science. The severity comes from EPA AQS and AirNow measurements. The causes come from what those agencies already published: EPA AQS sample qualifiers (the submitting agency flagging its own measurement), NWS Air Quality Alerts, NOAA Storm Events, and direct agency statements, with reporting as corroboration and a route back to primary sources. Named fires resolve against WFIGS/IRWIN and ICS-209 incident records, which normalize identity only. Every event names the sources it rests on and links out to them.
What would make this unnecessary. If EPA or NOAA published a canonical public event catalog with stable identifiers, we would rather point at it than maintain this. Until then the assembly, naming, ranking, and evidence retention are the contribution, and we keep them transparent enough to be checked, argued with, and corrected.
Episodes start as elevated-PM2.5 candidates in the monitor record (the same data behind the city rankings). Evidence is then gathered per candidate: agency and health-department statements, NOAA Storm Events records, and link-first news coverage. A resolution pass groups candidates into one named episode only when the retained evidence supports the same real-world source, and records its reasoning and uncertainties; everything else stays unattributed.
What can merge episodes. Retained evidence that they share one real-world source occurrence: overlapping timing with a plausible progression, compatible origin regions, and corroborating official or news records. The resolution pass must cite the evidence it used, by ID.
What can never merge them. Severity alone, proximity alone, the season, article counts, or a shared cause label without connecting evidence. No PM2.5 threshold is treated as proof of any cause.
The three outcomes. Resolve into a named episode; abstain, leaving the candidate unattributed (unknown means unknown, not "no smoke"); or record a dispute and keep the candidates separate.
Evidence roles. Official assessments carry the most weight, then corroboration, hypothesis, and context. Counts are never a credibility score: one agency determination outweighs any number of headlines.
What changes a record. EPA certifying provisional days, new qualified evidence, or editorial review. Nothing here is indexed or final until the catalog is editorially adopted.
Grouping policy common_sense_root_cause_grouping.v2, resolved Jul 24, 2026 · candidate events pm25-candidate-events.v1 (1265 candidates) · news evidence news-evidence-candidates.v1 (1786 items) · official matches pm25-official-source-matches.v2 (93 records). All records research-only pending editorial adoption.