Denver, Colorado Air Quality
Denver air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
Denver, CO · Air quality right now
The air quality index in Denver, CO is 51 (Moderate) right now — acceptable for most people.
Is it safe to be outside in Denver today?
AQI 51 Yes — air quality is Moderate
Fine for most; unusually sensitive people can take it easy.Main pollutant: PM2.5Observed 7:00 AM MDT
Pollutants right now
- PM2.511 µg/m³Main pollutantfine particles — smoke, exhaust, soot
- PM1012 µg/m³coarse particles — dust, pollen, ash
- Ozone27 µg/m³smog — builds on hot, sunny days
- NO₂23 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run for most; sensitive athletes can ease the intensity.
How to read Denver’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 Denver
Across the EPA’s county records from 2020 to 2025, Denver’s cleanest year was 2025 (median AQI 50) and its most polluted was 2021 (median AQI 55); the typical (median) day has held roughly steady since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 53 | 0 | PM2.5 | 17 | 212 | 137 |
| 2021 | 55 | 4 | Ozone | 31 | 202 | 128 |
| 2022 | 52 | 0 | Ozone | 7 | 197 | 161 |
| 2023 | 54 | 2 | Ozone | 4 | 228 | 131 |
| 2024 | 55 | 3 | Ozone | 26 | 208 | 129 |
| 2025 | 50 | 0 | Ozone | 6 | 175 | 184 |
“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 Denver?
- In the EPA's 2020–2025 county records, 2021 had the most days above AQI 100: 35 days (31 Unhealthy for Sensitive Groups, 4 Unhealthy or worse). It also had the highest median AQI, 55.
- How many unhealthy air days does Denver have?
- Across 2020–2025, 5% of the days reported for Denver's county had an AQI above 100 (100 of 2192), about 17 days a year. 2025 had 6 days.
- What's the main air pollutant in Denver?
- Ozone drove Denver's county AQI on the most days in 5 of 6 years (2020–2025); PM2.5 in 2020.