Mesa Air Quality in October
Across 2019–2025, Mesa's October air quality had a median AQI of 90 (Moderate) over 217 monitored days in the Phoenix-Mesa-Scottsdale, AZ area. 43.4% of October days (94 of 217) reached Unhealthy for Sensitive Groups or worse, and coarse dust (PM10) set the daily AQI on 45.6% of days. The cleanest October on record here was 2025 (median AQI 64, 1 day above 100) and the worst was 2021 (median 197, 31 days above 100, peak AQI 217).
- Good: 9.2%
- Moderate: 47.5%
- Unhealthy for Sensitive Groups: 17.1%
- Unhealthy or worse: 26.3%
Reduce Indoor Ozone in Mesa
Today's main pollutant in Mesa is ground-level ozone (AQI 27). 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 October?
Moderate on a typical day: median AQI 90 across 2019–2025, with 43.4% of October days above AQI 100. Coarse dust (PM10) is the main driver.
- ✓9.2% of October days were Good (AQI 0–50), 47.5% Moderate (51–100).
- ✓94 days of 217 reached AQI 101+; the October peak was 601.
- ✓Best October: 2025; worst October: 2021.
Frequently asked questions
What is the air quality like in Mesa in October?▾
Across 2019–2025, the median daily AQI in Mesa in October was 90 (Moderate). 9.2% of days were Good, 47.5% Moderate, and 43.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Mesa?▾
A typical October day in Mesa is Moderate (median AQI 90): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 2 of October days (43.4%) 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 October air quality problems?▾
Coarse dust (PM10) set the daily AQI on 45.6% of October days in Mesa. The highest October AQI recorded in 2019–2025 was 601 (Hazardous), in 2021.
Mesa October air quality, year by year
Mesa October 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 | 31 | 77 | 3 | 113 | PM10 |
| 2020 | 31 | 192 | 31 | 223 | O3 |
| 2021worst | 31 | 197 | 31 | 217 | O3 |
| 2022 | 31 | 58 | 2 | 601 | O3 |
| 2023 | 31 | 82 | 10 | 130 | PM10 |
| 2024 | 31 | 104 | 16 | 141 | PM10 |
| 2025cleanest | 31 | 64 | 1 | 123 | PM10 |
What October air means in Mesa
A typical October day in Mesa is Moderate (median AQI 90): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 2 of October days (43.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
October's median AQI of 90 is above Mesa's whole-year median of 79, making it one of the area's dirtier periods. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Mesa runs above the national October norm; 43.4% of its October days topped AQI 100 versus 1.3% nationally (above average).
October is part of Mesa's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Mesa
The latest EPA AirNow observation puts Mesa's AQI at 27 (O3). The figures above are multi-year month 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.