Fireworks
2024-12-31 fireworks episode affecting Phoenix-Mesa-Scottsdale, AZ, Tucson, AZ
Daily PM2.5 peaked at 210.3 µg/m³ near Phoenix across 2 covered metros home to 6.3 million people. 1 metro recorded their worst day on record.
Counting the extra PM2.5 above each metro's typical day, this event handed the average affected resident ≈ 9.8 cigarettes. Across everyone living in the affected metros, that is the collective equivalent of ≈ 61 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
The supplied retained evidence supports fireworks for this event; no supplied evidence establishes membership in a broader time-bounded episode.
Sequence: Phoenix (Dec 31) → Tucson (Jan 1)
Affected metros
| Metro | Peak PM2.5 | Cigarettes, whole event | Peak day | All-time standing |
|---|---|---|---|---|
| Phoenix-Mesa-Scottsdale, AZ | 210.3 µg/m³ | 12.8 | Jan 1, 2025 | Worst day on record |
| Tucson, AZ | 27.2 µg/m³ | 1.2 | Jan 1, 2025 | #17 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 3
- 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 2024-12-31, 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 IH — Fireworks. EPA AQS carries an agency-submitted informational qualifier (IH, Fireworks.) on 5 PM2.5 samples in the candidate CBSA on 2024-12-31, 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 192 PM2.5 samples in the candidate CBSA on 2025-01-01, 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 2
- High Pollution Advisory for PM2.5 for December 31, 2024 and January 1, 2025 ADEQ and Maricopa County issued a PM2.5 high-pollution advisory and No Burn Day covering the New Year's event period.
- Fireworks and air quality MAG reports that Maricopa County chemical analysis identifies consumer fireworks as the largest contributor to New Year’s Eve/Day PM2.5 exceedances and that the West Phoenix monitor had the nation's highest measured PM2.5 on January 1, 2025.
What remains uncertain
- Agency-submitted AQS qualifiers do not 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.