Springfield, IL Air Quality in September
Across 2019–2025, Springfield's September air quality had a median AQI of 46 (Good) over 210 monitored days in the Springfield, IL area. 0.0% of September days (0 of 210) reached Unhealthy for Sensitive Groups or worse, and fine particulate matter (PM2.5) set the daily AQI on 55.2% of days. The cleanest September on record here was 2024 (median AQI 36, 0 days above 100) and the worst was 2023 (median 54, 0 days above 100, peak AQI 78).
- Good: 60.0%
- Moderate: 40.0%
- Unhealthy for Sensitive Groups: 0.0%
- Unhealthy or worse: 0.0%
Reduce Indoor Ozone in Springfield
Today's main pollutant in Springfield is ground-level ozone (AQI 32). 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
As an Amazon Associate, we earn from qualifying purchases.
How is the air in Springfield in September?
Good on a typical day: median AQI 46 across 2019–2025, with 0.0% of September days above AQI 100. Fine particulate matter (PM2.5) is the main driver.
- ✓60.0% of September days were Good (AQI 0–50), 40.0% Moderate (51–100).
- ✓0 days of 210 reached AQI 101+; the September peak was 97.
- ✓Best September: 2024; worst September: 2023.
Frequently asked questions
What is the air quality like in Springfield in September?▾
Across 2019–2025, the median daily AQI in Springfield in September was 46 (Good). 60.0% of days were Good, 40.0% Moderate, and 0.0% reached Unhealthy for Sensitive Groups or worse, based on 210 monitored days in EPA's Air Quality System.
Is September a good time for outdoor exercise in Springfield?▾
A typical September day in Springfield sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of September days reached AQI 101+ in 2019–2025.
Which pollutant causes Springfield's September air quality problems?▾
Fine particulate matter (PM2.5) set the daily AQI on 55.2% of September days in Springfield. The highest September AQI recorded in 2019–2025 was 97 (Moderate), in 2023.
Springfield September air quality, year by year
Springfield September air quality by year (Springfield, IL, EPA AQS daily AQI)
| Year | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| 2019 | 30 | 48 | 0 | 61 | PM2.5 |
| 2020 | 30 | 43 | 0 | 62 | PM2.5 |
| 2021 | 30 | 45 | 0 | 74 | O3 |
| 2022 | 30 | 44 | 0 | 62 | PM2.5 |
| 2023worst | 30 | 54 | 0 | 78 | PM2.5 |
| 2024cleanest | 30 | 36 | 0 | 77 | O3 |
| 2025 | 30 | 53 | 0 | 97 | O3 |
What September air means in Springfield
A typical September day in Springfield sits in the Good range (median AQI 46), so running, cycling and children's outdoor play are fine for everyone on most days; fewer than 1% of September days reached AQI 101+ in 2019–2025.
September's median AQI of 46 is in line with Springfield's whole-year median of 44, so this period is neither a clean nor a dirty stretch for the area. Nationally, the median September AQI across every EPA metro area (100,699 metro-days, 2019–2025) is 43, so Springfield runs in line with the national September norm; 0.0% of its September days topped AQI 100 versus 2.7% nationally (below average).
September is part of Springfield's fall season (September, October, November); the fall page pools all three months.
Activity-specific thresholds: running, cycling, kids' sports.
Right now in Springfield
The latest EPA AirNow observation puts Springfield's AQI at 32 (O3). The figures above are multi-year month statistics, not today's reading.
View current Springfield air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Springfield, IL), 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.