Mesa Air Quality in May
Across 2019–2025, Mesa's May air quality had a median AQI of 90 (Moderate) over 217 monitored days in the Phoenix-Mesa-Scottsdale, AZ area. 32.3% of May days (70 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 71.4% of days. The cleanest May on record here was 2019 (median AQI 76, 3 days above 100) and the worst was 2024 (median 93, 13 days above 100, peak AQI 126).
- Good: 1.4%
- Moderate: 66.4%
- Unhealthy for Sensitive Groups: 31.8%
- Unhealthy or worse: 0.5%
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 May?
Moderate on a typical day: median AQI 90 across 2019–2025, with 32.3% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓1.4% of May days were Good (AQI 0–50), 66.4% Moderate (51–100).
- ✓70 days of 217 reached AQI 101+; the May peak was 161.
- ✓Best May: 2019; worst May: 2024.
Frequently asked questions
What is the air quality like in Mesa in May?▾
Across 2019–2025, the median daily AQI in Mesa in May was 90 (Moderate). 1.4% of days were Good, 66.4% Moderate, and 32.3% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is May a good time for outdoor exercise in Mesa?▾
A typical May 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 3 of May days (32.3%) 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 May air quality problems?▾
Ground-level ozone set the daily AQI on 71.4% of May days in Mesa. The highest May AQI recorded in 2019–2025 was 161 (Unhealthy), in 2024.
Mesa May air quality, year by year
Mesa May 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 | 76 | 3 | 127 | O3 |
| 2020 | 31 | 90 | 10 | 147 | O3 |
| 2021 | 31 | 93 | 11 | 129 | O3 |
| 2022 | 31 | 84 | 9 | 140 | O3 |
| 2023 | 31 | 90 | 12 | 161 | O3 |
| 2024worst | 31 | 93 | 13 | 126 | O3 |
| 2025 | 31 | 97 | 12 | 126 | O3 |
What May air means in Mesa
A typical May 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 3 of May days (32.3%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
May'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 May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Mesa runs above the national May norm; 32.3% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of Mesa's spring season (March, April, May); the spring 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 37 (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.