Cleveland Air Quality in May
Across 2019–2025, Cleveland's May air quality had a median AQI of 54 (Moderate) over 217 monitored days in the Cleveland-Elyria, OH area. 3.7% of May days (8 of 217) reached Unhealthy for Sensitive Groups or worse, and ground-level ozone set the daily AQI on 53.0% of days. The cleanest May on record here was 2025 (median AQI 44, 0 days above 100) and the worst was 2021 (median 55, 4 days above 100, peak AQI 115).
- Good: 41.0%
- Moderate: 55.3%
- Unhealthy for Sensitive Groups: 3.7%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Cleveland
Today's main pollutant in Cleveland is ground-level ozone (AQI 44). 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 Cleveland in May?
Moderate on a typical day: median AQI 54 across 2019–2025, with 3.7% of May days above AQI 100. Ground-level ozone is the main driver.
- ✓41.0% of May days were Good (AQI 0–50), 55.3% Moderate (51–100).
- ✓8 days of 217 reached AQI 101+; the May peak was 136.
- ✓Best May: 2025; worst May: 2021.
Frequently asked questions
What is the air quality like in Cleveland in May?▾
Across 2019–2025, the median daily AQI in Cleveland in May was 54 (Moderate). 41.0% of days were Good, 55.3% Moderate, and 3.7% 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 Cleveland?▾
A typical May day in Cleveland is Moderate (median AQI 54): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 27 of May days (3.7%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Cleveland's May air quality problems?▾
Ground-level ozone set the daily AQI on 53.0% of May days in Cleveland. The highest May AQI recorded in 2019–2025 was 136 (Unhealthy for Sensitive Groups), in 2021.
Cleveland May air quality, year by year
Cleveland May air quality by year (Cleveland-Elyria, OH, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 54 | 0 | 87 | PM2.5 |
| 2020 | 31 | 48 | 0 | 71 | O3 |
| 2021worst | 31 | 55 | 4 | 115 | O3 |
| 2022 | 31 | 53 | 0 | 84 | PM2.5 |
| 2023 | 31 | 63 | 1 | 105 | O3 |
| 2024 | 31 | 58 | 3 | 136 | O3 |
| 2025cleanest | 31 | 44 | 0 | 77 | O3 |
What May air means in Cleveland
A typical May day in Cleveland is Moderate (median AQI 54): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 27 of May days (3.7%) 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 54 is in line with Cleveland's whole-year median of 55, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median May AQI across every EPA metro area (104,064 metro-days, 2019–2025) is 44, so Cleveland runs above the national May norm; 3.7% of its May days topped AQI 100 versus 1.3% nationally (above average).
May is part of Cleveland's spring season (March, April, May); the spring page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Cleveland
The latest EPA AirNow observation puts Cleveland's AQI at 44 (O3). The figures above are multi-year month statistics, not today's reading.
View current Cleveland air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Cleveland-Elyria, OH), 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.