Cincinnati Air Quality in 2021
In 2021, Cincinnati's air quality (Cincinnati, OH-KY-IN area) had a median daily AQI of 57 (Moderate) across 365 monitored days. 8 days (2.2%) reached Unhealthy for Sensitive Groups or worse, 92 were Good, and the year's peak AQI was 140 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 299 of those days. The cleanest month of 2021 was October (median AQI 53, 0 days above 100) and the worst was August (median 59, 3 days above 100, peak 140).
- Good: 25.2%
- Moderate: 72.6%
- Unhealthy for Sensitive Groups: 2.2%
- Unhealthy or worse: 0.0%
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How was Cincinnati's air quality in 2021?
Moderate on a typical day: median AQI 57, with 8 days above AQI 100 out of 365 monitored — the 3rd cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 140 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 299 days.
- ✓Cleanest month: October; worst: August.
Frequently asked questions
What was the average AQI in Cincinnati in 2021?▾
EPA's Air Quality System puts Cincinnati's (Cincinnati, OH-KY-IN) median daily AQI for 2021 at 57, which is Moderate. 8 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 140.
Which month had the worst air quality in Cincinnati in 2021?▾
The cleanest month of 2021 was October (median AQI 53, 0 days above 100) and the worst was August (median 59, 3 days above 100, peak 140).
Was 2021 a good or bad year for Cincinnati's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 3rd cleanest by days above AQI 100. 2021's median of 57 is in line with the area's typical annual median of 56.
Cincinnati month by month in 2021
Cincinnati air quality month by month, 2021 (Cincinnati, OH-KY-IN, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 57 | 0 | 82 | PM2.5 |
| February | 28 | 63 | 1 | 107 | PM2.5 |
| March | 31 | 55 | 0 | 82 | PM2.5 |
| April | 30 | 57 | 0 | 94 | PM2.5 |
| May | 31 | 55 | 0 | 97 | PM2.5 |
| June | 30 | 60 | 2 | 101 | PM2.5 |
| July | 31 | 71 | 2 | 122 | PM2.5 |
| Augustworst | 31 | 59 | 3 | 140 | PM2.5 |
| September | 30 | 57 | 0 | 77 | PM2.5 |
| Octobercleanest | 31 | 53 | 0 | 68 | PM2.5 |
| November | 30 | 54 | 0 | 85 | PM2.5 |
| December | 31 | 54 | 0 | 70 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 3rd cleanest by days above AQI 100.
2021's median of 57 is in line with the area's typical annual median of 56.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Cincinnati
The latest EPA AirNow observation puts Cincinnati's AQI at 39 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current Cincinnati air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Cincinnati, OH-KY-IN), 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.