Indianapolis Air Quality in 2021
In 2021, Indianapolis's air quality (Indianapolis-Carmel-Anderson, IN area) had a median daily AQI of 58 (Moderate) across 365 monitored days. 7 days (1.9%) reached Unhealthy for Sensitive Groups or worse, 80 were Good, and the year's peak AQI was 114 (Unhealthy for Sensitive Groups). Fine particulate matter (PM2.5) set the daily AQI on 317 of those days. The cleanest month of 2021 was October (median AQI 53, 0 days above 100) and the worst was November (median 54, 3 days above 100, peak 111).
- Good: 21.9%
- Moderate: 76.2%
- Unhealthy for Sensitive Groups: 1.9%
- Unhealthy or worse: 0.0%
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How was Indianapolis's air quality in 2021?
Moderate on a typical day: median AQI 58, with 7 days above AQI 100 out of 365 monitored — the 4th cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 114 (Unhealthy for Sensitive Groups).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 317 days.
- ✓Cleanest month: October; worst: November.
Frequently asked questions
What was the average AQI in Indianapolis in 2021?▾
EPA's Air Quality System puts Indianapolis's (Indianapolis-Carmel-Anderson, IN) median daily AQI for 2021 at 58, which is Moderate. 7 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 114.
Which month had the worst air quality in Indianapolis in 2021?▾
The cleanest month of 2021 was October (median AQI 53, 0 days above 100) and the worst was November (median 54, 3 days above 100, peak 111).
Was 2021 a good or bad year for Indianapolis's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 4th cleanest by days above AQI 100. 2021's median of 58 is in line with the area's typical annual median of 56.
Indianapolis month by month in 2021
Indianapolis air quality month by month, 2021 (Indianapolis-Carmel-Anderson, IN, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 58 | 0 | 81 | PM2.5 |
| February | 28 | 65 | 0 | 98 | PM2.5 |
| March | 31 | 58 | 0 | 99 | PM2.5 |
| April | 30 | 60 | 1 | 114 | PM2.5 |
| May | 31 | 57 | 0 | 84 | PM2.5 |
| June | 30 | 60 | 0 | 100 | PM2.5 |
| July | 31 | 68 | 1 | 112 | PM2.5 |
| August | 31 | 60 | 1 | 106 | PM2.5 |
| September | 30 | 58 | 1 | 101 | PM2.5 |
| Octobercleanest | 31 | 53 | 0 | 68 | PM2.5 |
| Novemberworst | 30 | 54 | 3 | 111 | PM2.5 |
| December | 31 | 59 | 0 | 82 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 4th cleanest by days above AQI 100.
2021's median of 58 is in line with the area's typical annual median of 56.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Indianapolis
The latest EPA AirNow observation puts Indianapolis's AQI at 44 (PM2.5). The figures above are multi-year annual statistics, not today's reading.
View current Indianapolis air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Indianapolis-Carmel-Anderson, 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.