Mesa Air Quality in January
Across 2019–2025, Mesa's January air quality had a median AQI of 81 (Moderate) over 217 monitored days in the Phoenix-Mesa-Scottsdale, AZ area. 36.0% of January days (78 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 50.7% of days. The cleanest January on record here was 2019 (median AQI 63, 0 days above 100) and the worst was 2021 (median 143, 31 days above 100, peak AQI 297).
- Good: 6.5%
- Moderate: 57.6%
- Unhealthy for Sensitive Groups: 22.6%
- Unhealthy or worse: 13.4%
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.
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How is the air in Mesa in January?
Moderate on a typical day: median AQI 81 across 2019–2025, with 36.0% of January days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓6.5% of January days were Good (AQI 0–50), 57.6% Moderate (51–100).
- ✓78 days of 217 reached AQI 101+; the January peak was 1215.
- ✓Best January: 2019; worst January: 2021.
Frequently asked questions
What is the air quality like in Mesa in January?▾
Across 2019–2025, the median daily AQI in Mesa in January was 81 (Moderate). 6.5% of days were Good, 57.6% Moderate, and 36.0% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is January a good time for outdoor exercise in Mesa?▾
A typical January day in Mesa is Moderate (median AQI 81): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of January days (36.0%) 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 January air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 50.7% of January days in Mesa. The highest January AQI recorded in 2019–2025 was 1215 (Hazardous), in 2021.
Mesa January air quality, year by year
Mesa January air quality by year (Phoenix-Mesa-Scottsdale, AZ, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019cleanest | 31 | 63 | 0 | 93 | PM2.5 |
| 2020 | 31 | 75 | 8 | 224 | PM2.5 |
| 2021worst | 31 | 143 | 31 | 297 | O3 |
| 2022 | 31 | 143 | 30 | 187 | O3 |
| 2023 | 31 | 67 | 2 | 160 | PM2.5 |
| 2024 | 31 | 69 | 2 | 261 | PM2.5 |
| 2025 | 31 | 84 | 5 | 1215 | PM10 |
What January air means in Mesa
A typical January day in Mesa is Moderate (median AQI 81): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 3 of January days (36.0%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
January's median AQI of 81 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 January AQI across every EPA metro area (95,602 metro-days, 2019–2025) is 39, so Mesa runs above the national January norm; 36.0% of its January days topped AQI 100 versus 0.7% nationally (above average).
January is part of Mesa's winter season (December, January, February); the winter 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.