Naperville, Illinois Air Quality
Naperville air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
Naperville, IL · Air quality right now
The air quality index in Naperville, IL is 31 (Good) right now — safe for outdoor activity.
Is it safe to be outside in Naperville today?
AQI 31 Yes — air quality is Good
Air is clean — great for outdoor activity.Main pollutant: PM2.5Observed 5:00 AM CDT
Pollutants right now
- PM2.56.6 µg/m³Main pollutantfine particles — smoke, exhaust, soot
- PM106.6 µg/m³coarse particles — dust, pollen, ash
- Ozone62 µg/m³smog — builds on hot, sunny days
- NO₂5.3 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run — no air-quality limits on outdoor exercise.
How to read Naperville’s air quality
Guides: The AQI Scale, Explained · Air Quality Alerts, Decoded · How to Read a Wildfire Smoke Map · Why Wildfire Smoke Travels 1,000 Miles.
Air quality over time in Naperville
Across the EPA’s county records from 2020 to 2025, Naperville’s cleanest year was 2025 (median AQI 42) and its most polluted was 2023 (median AQI 53); the typical (median) day has held roughly steady since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 47 | 1 | PM2.5 | 3 | 149 | 213 |
| 2021 | 51 | 0 | PM2.5 | 2 | 184 | 179 |
| 2022 | 47 | 0 | PM2.5 | 1 | 165 | 199 |
| 2023 | 53 | 6 | PM2.5 | 11 | 202 | 146 |
| 2024 | 45 | 0 | PM2.5 | 0 | 136 | 230 |
| 2025 | 42 | 1 | PM2.5 | 5 | 126 | 233 |
“USG” is Unhealthy for Sensitive Groups (AQI 101–150); “Unhealthy+” combines the Unhealthy, Very Unhealthy, and Hazardous days. In 2024 the EPA tightened the annual fine-particle (PM2.5) standard to 9 µg/m³ from the previous 12 µg/m³, so counties near the old limit read worse against the new one. Source: EPA AQS annual summaries, 2020–2025.
Frequently asked
- What was the worst year for air quality in Naperville?
- In the EPA's 2020–2025 county records, 2023 had the most days above AQI 100: 17 days (11 Unhealthy for Sensitive Groups, 6 Unhealthy or worse). It also had the highest median AQI, 53.
- How many unhealthy air days does Naperville have?
- Across 2020–2025, 1% of the days reported for Naperville's county had an AQI above 100 (30 of 2192), about 5 days a year. 2025 had 6 days.
- What's the main air pollutant in Naperville?
- PM2.5: it drove Naperville's county AQI on the most days in every year of the EPA's 2020–2025 records.