Indianapolis Air Quality in October
Across 2019–2025, Indianapolis's October air quality had a median AQI of 55 (Moderate) over 217 monitored days in the Indianapolis-Carmel-Anderson, IN area. 1.4% of October days (3 of 217) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 88.9% of days. The cleanest October on record here was 2025 (median AQI 42, 0 days above 100) and the worst was 2024 (median 64, 2 days above 100, peak AQI 138).
- Good: 35.9%
- Moderate: 62.7%
- Unhealthy for Sensitive Groups: 1.4%
- Unhealthy or worse: 0.0%
Extra Protection for Indianapolis Homes
Air quality in Indianapolis is moderate (AQI 55), with fine particles (PM2.5) the main concern. A True-HEPA purifier gives sensitive groups — kids, seniors and anyone with asthma or allergies — cleaner air indoors on days like today.
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How is the air in Indianapolis in October?
Moderate on a typical day: median AQI 55 across 2019–2025, with 1.4% of October days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓35.9% of October days were Good (AQI 0–50), 62.7% Moderate (51–100).
- ✓3 days of 217 reached AQI 101+; the October peak was 138.
- ✓Best October: 2025; worst October: 2024.
Frequently asked questions
What is the air quality like in Indianapolis in October?▾
Across 2019–2025, the median daily AQI in Indianapolis in October was 55 (Moderate). 35.9% of days were Good, 62.7% Moderate, and 1.4% reached Unhealthy for Sensitive Groups or worse, based on 217 monitored days in EPA's Air Quality System.
Is October a good time for outdoor exercise in Indianapolis?▾
A typical October day in Indianapolis is Moderate (median AQI 55): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 71 of October days (1.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
Which pollutant causes Indianapolis's October air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 88.9% of October days in Indianapolis. The highest October AQI recorded in 2019–2025 was 138 (Unhealthy for Sensitive Groups), in 2024.
Indianapolis October air quality, year by year
Indianapolis October air quality by year (Indianapolis-Carmel-Anderson, IN, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 31 | 55 | 1 | 106 | PM2.5 |
| 2020 | 31 | 51 | 0 | 68 | PM2.5 |
| 2021 | 31 | 53 | 0 | 68 | PM2.5 |
| 2022 | 31 | 60 | 0 | 89 | PM2.5 |
| 2023 | 31 | 53 | 0 | 90 | PM2.5 |
| 2024worst | 31 | 64 | 2 | 138 | PM2.5 |
| 2025cleanest | 31 | 42 | 0 | 80 | PM2.5 |
What October air means in Indianapolis
A typical October day in Indianapolis is Moderate (median AQI 55): outdoor exercise is acceptable for most people, but unusually sensitive individuals should watch for symptoms, and about 1 day in 71 of October days (1.4%) reached AQI 101+ — the level at which EPA advises people with asthma, children and older adults to shorten hard outdoor exertion.
October's median AQI of 55 is in line with Indianapolis's whole-year median of 56, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median October AQI across every EPA metro area (102,872 metro-days, 2019–2025) is 38, so Indianapolis runs above the national October norm; 1.4% of its October days topped AQI 100 versus 1.3% nationally (about the same).
October is part of Indianapolis's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Indianapolis
The latest EPA AirNow observation puts Indianapolis's AQI at 55 (PM2.5). The figures above are multi-year month 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.