Peoria Best & Worst AQI Days: Air Quality Guide
The worst air quality day on record for Peoria (Peoria, IL area) was August 1, 2025, when the daily AQI reached 154 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season. Across 2,449 monitored days in 2019–2025, 3 of the 10 worst days were Unhealthy (AQI 151+) or worse; 8 of the 10 were driven by ground-level ozone and 2 by fine particulate matter (PM2.5), and 8 of them fell in 2023. The cleanest day was February 26, 2020 at AQI 11 (Good); the 10 best days span 5 different years.
Improve Indoor Air Quality
Even with good outdoor air in Peoria, indoor PM2.5, dust and allergens build up. A True-HEPA purifier keeps a bedroom or office consistently clean.
Recommended: Levoit Core 400S — True HEPA · CADR ~141 CFM · rooms up to 219 sq ft
As an Amazon Associate, we earn from qualifying purchases.
When were Peoria's worst and best air quality days?
Worst: August 1, 2025, AQI 154 (Unhealthy, PM2.5). Best: February 26, 2020, AQI 11 (Good). Based on 2,449 EPA-monitored days in the Peoria, IL area, 2019–2025.
- ✓3 of the 10 worst days were Unhealthy (AQI 151+) or worse; the 10th-worst was AQI 129 (Unhealthy for Sensitive Groups).
- ✓Ground-level ozone drove 8 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 Peoria?▾
August 1, 2025: the Peoria, IL area's daily AQI hit 154 (Unhealthy), driven by fine particulate matter (PM2.5), in wildfire smoke season. That is the highest of 2,449 monitored days in 2019–2025.
What was the best air quality day in Peoria?▾
February 26, 2020, with a daily AQI of 11 (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 Peoria's worst air quality day in 2025?▾
August 1, 2025, AQI 154 (Unhealthy), set by fine particulate matter (PM2.5), in wildfire smoke season.
Which pollutant causes Peoria's worst air days?▾
Ground-level ozone set the AQI on 8 of the 10 worst days; fine particulate matter (PM2.5) on 2. The tables above list the defining pollutant for every day.
Peoria's 10 worst air quality days, 2019–2025
Highest daily AQI recorded for the Peoria, 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 | (2025 page) | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 2 | (2025 page) | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
| 3 | (2023 page) | 151 | Unhealthy | O3 — ground-level ozone |
| 4 | (2023 page) | 143 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone 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 | O3 — ground-level ozone, in peak ozone season |
| 7 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 8 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 9 | (2023 page) | 133 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
| 10 | (2023 page) | 129 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season |
Worst day of each year in Peoria
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 | 101 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2020 | 115 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2021 | 101 | Unhealthy for Sensitive Groups | O3 — ground-level ozone, in peak ozone season | |
| 2022 | 100 | Moderate | O3 — ground-level ozone, in peak ozone season | |
| 2023 | 151 | Unhealthy | O3 — ground-level ozone | |
| 2024 | 100 | Moderate | O3 — ground-level ozone, in peak ozone season | |
| 2025 | 154 | Unhealthy | PM2.5 — fine particulate matter (PM2.5), in wildfire smoke season |
Peoria's 10 best air quality days, 2019–2025
Lowest daily AQI recorded for the Peoria, IL area. Ties are listed most recent first.
| # | Date | AQI | Category | Defining pollutant |
|---|---|---|---|---|
| 1 | (2020 page) | 11 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 2 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 3 | (2024 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 4 | (2019 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 5 | (2019 page) | 12 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 6 | (2025 page) | 13 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 7 | (2021 page) | 13 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 8 | (2025 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 9 | (2024 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
| 10 | (2020 page) | 14 | Good | PM2.5 — fine particulate matter (PM2.5) |
Right now in Peoria
The latest EPA AirNow observation puts Peoria's AQI at 42 (PM2.5). The days above are historical records, not today's reading.
View current Peoria air quality →Source: EPA Air Quality System (AQS) pre-generated Daily AQI by CBSA files — daily AQI by CBSA (Peoria, 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.