Springfield, IL Air Quality in 2021
In 2021, Springfield's air quality (Springfield, IL area) had a median daily AQI of 43 (Good) across 362 monitored days. 0 days (0.0%) reached Unhealthy for Sensitive Groups or worse, 233 were Good, and the year's peak AQI was 98 (Moderate). Fine particulate matter (PM2.5) set the daily AQI on 262 of those days. The cleanest month of 2021 was October (median AQI 32, 0 days above 100) and the worst was July (median 55, 0 days above 100, peak 98).
- Good: 64.4%
- Moderate: 35.6%
- 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
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How was Springfield's air quality in 2021?
Good on a typical day: median AQI 43, with 0 days above AQI 100 out of 362 monitored — the 1st cleanest of 7 years on record for the area.
- ✓Peak AQI in 2021: 98 (Moderate).
- ✓Fine particulate matter (PM2.5) was the main pollutant on 262 days.
- ✓Cleanest month: October; worst: July.
Frequently asked questions
What was the average AQI in Springfield in 2021?▾
EPA's Air Quality System puts Springfield's (Springfield, IL) median daily AQI for 2021 at 43, which is Good. 0 days were Unhealthy for Sensitive Groups or worse and the year's highest AQI was 98.
Which month had the worst air quality in Springfield in 2021?▾
The cleanest month of 2021 was October (median AQI 32, 0 days above 100) and the worst was July (median 55, 0 days above 100, peak 98).
Was 2021 a good or bad year for Springfield's air?▾
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 1st cleanest by days above AQI 100 — the best year on record here. 2021's median of 43 is in line with the area's typical annual median of 44.
Springfield month by month in 2021
Springfield air quality month by month, 2021 (Springfield, IL, EPA AQS daily AQI)
| Month | Days monitored | Median AQI | Days above 100 | Peak AQI | Main pollutant |
|---|---|---|---|---|---|
| January | 31 | 41 | 0 | 62 | PM2.5 |
| February | 27 | 47 | 0 | 67 | PM2.5 |
| March | 31 | 41 | 0 | 68 | PM2.5 |
| April | 30 | 41 | 0 | 76 | O3 |
| May | 31 | 41 | 0 | 59 | O3 |
| June | 30 | 45 | 0 | 80 | O3 |
| Julyworst | 31 | 55 | 0 | 98 | PM2.5 |
| August | 31 | 53 | 0 | 82 | PM2.5 |
| September | 30 | 45 | 0 | 74 | O3 |
| Octobercleanest | 31 | 32 | 0 | 60 | PM2.5 |
| November | 28 | 43 | 0 | 78 | PM2.5 |
| December | 31 | 52 | 0 | 71 | PM2.5 |
How 2021 compares
Among the 7 years EPA has published for the area (2019–2025), 2021 ranks 1st cleanest by days above AQI 100 — the best year on record here.
2021's median of 43 is in line with the area's typical annual median of 44.
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 annual 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.