Fireworks
Fireworks episode, 2013-07-04
Daily PM2.5 peaked at 76.9 µg/m³ near Ogden across 1 covered metro home to 667,681 people. 1 metro placed a top-ten day in their record.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 3.2 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 2.1 million cigarettes. An awareness illustration of outdoor exposure at 22 µg/m³ per cigarette (Berkeley Earth), counting only the event's ranked days; not a medical dose.
Episode peak
-- cigarettes
The smoke map's scale, replayed over this event: the surface interpolates between covered metros' daily records, framed to the affected region. Hover for a reading, click a metro to pin it to the card. Days a monitor did not report draw nothing.
What happened, in the record
Qualified frozen evidence supports fireworks as the broad cause for this time-bounded episode.
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Ogden-Clearfield, UT | 76.9 µg/m³ | 3.5 | Jul 4, 2013 | #2 of its top days |
"Cigarettes, whole event" totals a metro's ranked event days at 22 µg/m³ per cigarette: what a person outdoors there breathed across the event, as the illustration. "All-time standing" is where this episode's days sit in each metro's ranked record (worst-area measure, since 1999). Full local context is on each metro's Air Records page.
The evidence
EPA AQS monitor qualifier 2
- AQS PM2.5 qualifier IH — Fireworks. EPA AQS carries an agency-submitted informational qualifier (IH, Fireworks.) on 10 PM2.5 samples in the candidate CBSA on 2013-07-04, identifying fireworks as affecting the samples. An informational qualifier is an official submitting-agency flag, not a request for exclusion or an EPA-concurred determination.
- AQS PM2.5 qualifier RH — Fireworks. EPA AQS carries an agency-submitted request-exclusion qualifier (RH, Fireworks.) on 1 PM2.5 sample in the candidate CBSA on 2013-07-04, identifying fireworks as affecting the sample. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
Agency and publisher pages 1
- Special Notice: Notice of Public Comment Period for PM2.5 Exceptional Event — Independence Day Fireworks, July 4, 2013 Utah's official exceptional-event notice attributes the Ogden monitor's July 4 PM2.5 value to firework-display emissions.
What remains uncertain
- AQS qualifiers are submitting-agency causal flags and do not by themselves establish EPA concurrence.
- The evidence resolves the broad cause but does not require a named fire, facility, or incident.
Status and provenance
Research preview: this record carries research-only status and its boundaries, cause, and name may change as evidence review completes. Grouping policy common_sense_root_cause_grouping.v2. The cause label reflects the assembled evidence above, not an IAQng detection formula.