Mesa Air Quality in Fall
Across 2019–2025, Mesa's fall (September–November) air quality had a median AQI of 82 (Moderate) over 637 monitored days in the Phoenix-Mesa-Scottsdale, AZ area. 31.6% of fall days (201 of 637) reached Unhealthy for Sensitive Groups or worse, and coarse dust (PM10) set the daily AQI on 47.6% of days. The cleanest fall on record here was 2022 (median AQI 67, 7 days above 100) and the worst was 2021 (median 187, 67 days above 100, peak AQI 239).
- Good: 8.6%
- Moderate: 59.8%
- Unhealthy for Sensitive Groups: 16.2%
- Unhealthy or worse: 15.4%
Reduce Indoor Ozone in Mesa
Today's main pollutant in Mesa is ground-level ozone (AQI 37). 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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How is the air in Mesa in fall?
Moderate on a typical day: median AQI 82 across 2019–2025, with 31.6% of fall days above AQI 100. Coarse dust (PM10) is the main driver.
- ✓8.6% of fall days were Good (AQI 0–50), 59.8% Moderate (51–100).
- ✓201 days of 637 reached AQI 101+; the fall peak was 601.
- ✓Cleanest month: November; worst month: October.
Frequently asked questions
What is the air quality like in Mesa in fall?▾
Across 2019–2025, the median daily AQI in Mesa in fall was 82 (Moderate). 8.6% of days were Good, 59.8% Moderate, and 31.6% reached Unhealthy for Sensitive Groups or worse, based on 637 monitored days in EPA's Air Quality System.
Is fall a good time for outdoor exercise in Mesa?▾
A typical fall day in Mesa is Moderate (median AQI 82): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of fall days (31.6%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Mesa's fall air quality problems?▾
Coarse dust (PM10) set the daily AQI on 47.6% of fall days in Mesa. The highest fall AQI recorded in 2019–2025 was 601 (Hazardous), in 2021.
Mesa fall air quality, year by year
Mesa fall air quality by year (Phoenix-Mesa-Scottsdale, AZ, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 91 | 77 | 13 | 151 | PM10 |
| 2020 | 91 | 109 | 58 | 522 | O3 |
| 2021worst | 91 | 187 | 67 | 239 | O3 |
| 2022cleanest | 91 | 67 | 7 | 601 | O3 |
| 2023 | 91 | 74 | 14 | 164 | PM10 |
| 2024 | 91 | 90 | 35 | 166 | PM10 |
| 2025 | 91 | 67 | 7 | 329 | PM10 |
What fall air means in Mesa
A typical fall day in Mesa is Moderate (median AQI 82): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of fall days (31.6%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Fall's median AQI of 82 is in line with Mesa's whole-year median of 79, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median Fall AQI across every EPA metro area (296,275 metro-days, 2019–2025) is 40, so Mesa runs above the national Fall norm; 31.6% of its Fall days topped AQI 100 versus 1.5% nationally (above average).
Within the season, November is the cleanest month (median AQI 79, 15.2% of days above 100) and October the worst (median 90, 43.4% above 100).
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Mesa
The latest EPA AirNow observation puts Mesa's AQI at 37 (O3). The figures above are multi-year season statistics, not today's reading.
View current Mesa 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.