Phoenix Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Phoenix (Phoenix-Mesa-Scottsdale, AZ area) was January 8, 2025, when the daily AQI reached 1215 (Hazardous), set by coarse dust (PM10). Across 2,557 monitored days in 2019–2025, 10 of the 10 worst days were Unhealthy (AQI 151+) or worse; 10 of the 10 were driven by coarse dust (PM10), and 6 of them fell in 2019. The cleanest day was July 25, 2021 at AQI 35 (Good); the 10 best days span 5 different years.
Reduce Indoor Ozone in Phoenix
Today's main pollutant in Phoenix is ground-level ozone (AQI 47). Important: standard HEPA filters do NOT remove ozone — only a purifier with a substantial activated-carbon bed adsorbs it. The biggest wins are cutting indoor sources (gas appliances, certain "ionizer" purifiers) and ventilating when outdoor ozone is low (early morning). A high-carbon unit helps with the gases and VOCs that linger indoors.
Recommended: Levoit Core 300 — True HEPA + activated carbon · CADR ~141 CFM · rooms up to 219 sq ft
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When were Phoenix's worst and best air quality days?
Worst: January 8, 2025, AQI 1215 (Hazardous, PM10). Best: July 25, 2021, AQI 35 (Good). Based on 2,557 EPA-monitored days in the Phoenix-Mesa-Scottsdale, AZ area, 2019–2025.
- ✓10 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 709 (Hazardous).
- ✓Coarse dust (PM10) drove 10 of the 10 worst days.
- ✓2019 accounts for 6 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Phoenix?▾
January 8, 2025: the Phoenix-Mesa-Scottsdale, AZ area's daily AQI hit 1215 (Hazardous), driven by coarse dust (PM10). That is the highest of 2,557 monitored days in 2019–2025.
What was the best air quality day in Phoenix?▾
July 25, 2021, with a daily AQI of 35 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Phoenix's worst air quality day in 2025?▾
January 8, 2025, AQI 1215 (Hazardous), set by coarse dust (PM10).
Which pollutant causes Phoenix's worst air days?▾
Coarse dust (PM10) set the AQI on 10 of the 10 worst days. The tables above list the defining pollutant for every day.
Phoenix's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Phoenix-Mesa-Scottsdale, AZ area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2025 page) | 1215 | Hazardous | PM10 — coarse dust (PM10) |
| 2 | (2020 page) | 1194 | Hazardous | PM10 — coarse dust (PM10) |
| 3 | (2019 page) | 929 | Hazardous | PM10 — coarse dust (PM10) |
| 4 | (2019 page) | 929 | Hazardous | PM10 — coarse dust (PM10) |
| 5 | (2019 page) | 929 | Hazardous | PM10 — coarse dust (PM10) |
| 6 | (2019 page) | 929 | Hazardous | PM10 — coarse dust (PM10) |
| 7 | (2019 page) | 929 | Hazardous | PM10 — coarse dust (PM10) |
| 8 | (2019 page) | 929 | Hazardous | PM10 — coarse dust (PM10) |
| 9 | (2025 page) | 763 | Hazardous | PM10 — coarse dust (PM10) |
| 10 | (2023 page) | 709 | Hazardous | PM10 — coarse dust (PM10) |
Worst day of each year in Phoenix
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 929 | Hazardous | PM10 — coarse dust (PM10) | |
| 2020 | 1194 | Hazardous | PM10 — coarse dust (PM10) | |
| 2021 | 297 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5) | |
| 2022 | 689 | Hazardous | PM10 — coarse dust (PM10) | |
| 2023 | 709 | Hazardous | PM10 — coarse dust (PM10) | |
| 2024 | 337 | Hazardous | PM10 — coarse dust (PM10) | |
| 2025 | 1215 | Hazardous | PM10 — coarse dust (PM10) |
Phoenix's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Phoenix-Mesa-Scottsdale, AZ area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2021 page) | 35 | Good | O3 — ground-level ozone, in peak ozone season |
| 2 | (2019 page) | 35 | Good | O3 — ground-level ozone |
| 3 | (2019 page) | 36 | Good | O3 — ground-level ozone |
| 4 | (2025 page) | 37 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2023 page) | 37 | Good | O3 — ground-level ozone |
| 6 | (2023 page) | 37 | Good | O3 — ground-level ozone |
| 7 | (2019 page) | 37 | Good | O3 — ground-level ozone |
| 8 | (2019 page) | 37 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2024 page) | 38 | Good | O3 — ground-level ozone |
| 10 | (2024 page) | 38 | Good | O3 — ground-level ozone |
Right now in Phoenix
The latest EPA AirNow observation puts Phoenix's AQI at 47 (O3). The days above are historical records, not today's reading.
View current Phoenix air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Phoenix-Mesa-Scottsdale, AZ), 2019–2025. Daily AQI per CBSA is the highest AQI reported by any monitor in the area that day; the defining parameter is the pollutant that set it. Month and season statistics pool every such day in the period across all years listed. Retrieved 2026-09-09.