Springfield Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Springfield (Springfield, IL area) was June 28, 2023, when the daily AQI reached 247 (Very Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,544 monitored days in 2019–2025, 3 of the 10 worst days were Unhealthy (AQI 151+) or worse; 5 of the 10 were driven by ground-level ozone and 5 by fine particulate matter (PM2.5), and 8 of them fell in 2023. The cleanest day was November 3, 2019 at AQI 6 (Good); the 10 best days span 5 different years.
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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When were Springfield's worst and best air quality days?
Worst: June 28, 2023, AQI 247 (Very Unhealthy, PM2.5). Best: November 3, 2019, AQI 6 (Good). Based on 2,544 EPA-monitored days in the Springfield, IL area, 2019–2025.
- ✓3 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 122 (Unhealthy for Sensitive Groups).
- ✓Ground-level ozone drove 5 of the 10 worst days.
- ✓2023 accounts for 8 of the 10 worst days.
Frequently asked questions
What was the worst air quality day in Springfield?▾
June 28, 2023: the Springfield, IL area's daily AQI hit 247 (Very Unhealthy), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,544 monitored days in 2019–2025.
What was the best air quality day in Springfield?▾
November 3, 2019, with a daily AQI of 6 (Good). The daily AQI is the highest reading from any monitor in the area, so even the cleanest day reflects the area's worst monitor.
What was Springfield's worst air quality day in 2025?▾
August 1, 2025, AQI 142 (Unhealthy for Sensitive Groups), set by fine particulate matter (PM2.5), in wildfire smoke season.
Which pollutant causes Springfield's worst air days?▾
Ground-level ozone set the AQI on 5 of the 10 worst days; fine particulate matter (PM2.5) on 5. The tables above list the defining pollutant for every day.
Springfield's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Springfield, IL area (EPA AQS). The daily AQI is the highest reading from any monitor in the area that day.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2023 page) | 247 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2023 page) | 160 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2023 page) | 160 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 4 | (2025 page) | 142 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 5 | (2023 page) | 136 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 6 | (2023 page) | 133 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 7 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone |
| 8 | (2023 page) | 129 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 9 | (2022 page) | 126 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 10 | (2023 page) | 122 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
Worst day of each year in Springfield
The single highest-AQI day in each year on record. Click a year for its full month-by-month statistics.
| Year | Worst day | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 2019 | 87 | Moderate | O3 — ground-level ozone, in peak ozone season | |
| 2020 | 97 | Moderate | O3 — ground-level ozone, in peak ozone season | |
| 2021 | 98 | Moderate | PM2.5 — fine particulate matter (PM2.5) | |
| 2022 | 126 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2023 | 247 | Very Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season | |
| 2024 | 105 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2025 | 142 | Unhealthy for Sensitive Groups | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Springfield's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Springfield, IL area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2019 page) | 6 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 2 | (2019 page) | 7 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 3 | (2024 page) | 8 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2020 page) | 9 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2019 page) | 9 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2025 page) | 11 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2022 page) | 11 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2025 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 10 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Springfield
The latest EPA AirNow observation puts Springfield's AQI at 32 (O3). The days above are historical records, 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.