Fireworks
2022-12-31 Tucson, AZ and Phoenix-Mesa-Scottsdale, AZ fireworks episode
Daily PM2.5 peaked at 68.4 µg/m³ near Phoenix across 2 covered metros home to 6.3 million people.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 2.3 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 14 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 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.
Sequence: Tucson (Dec 31) → Phoenix (Jan 1)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Phoenix-Mesa-Scottsdale, AZ | 68.4 µg/m³ | 3.1 | Jan 1, 2023 | #19 of its top days |
| Tucson, AZ | 26.4 µg/m³ | 1.2 | Dec 31, 2022 | #18 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 RH — Fireworks. EPA AQS carries an agency-submitted request-exclusion qualifier (RH, Fireworks.) on 72 PM2.5 samples in the candidate CBSA on 2022-12-31, identifying fireworks as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
- AQS PM2.5 qualifier RH — Fireworks. EPA AQS carries an agency-submitted request-exclusion qualifier (RH, Fireworks.) on 96 PM2.5 samples in the candidate CBSA on 2023-01-01, identifying fireworks as affecting the samples. A request-exclusion qualifier is an official submitting-agency causal claim, but this endpoint does not establish EPA concurrence.
Agency and publisher pages 3
- Air quality monitors catch New Year's celebrations Reporting on southern Arizona’s post-New-Year monitoring says Pima County Department of Environmental Quality considered fireworks and wood burning the most likely causes of elevated fine particulate levels; this corroborates the Tucson portion but does not isolate fireworks from wood burning.
- PM2.5 High Pollution Advisory issued for Saturday, December 31 and Sunday, January 1 ADEQ issued a PM2.5 advisory for the event dates; the advisory is contemporaneous but is prospective and does not itself attribute the observed event to fireworks.
- ADEQ wants people to limit fireworks in metro Phoenix because of air quality Contemporaneous reporting says ADEQ asked metro-Phoenix residents to limit fireworks during the advisory, but this is not a post-event attribution.
What remains uncertain
- Agency-submitted AQS qualifiers support attribution but do not by themselves establish EPA concurrence.
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.