Frederick, Maryland Air Quality
Frederick air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
Frederick, MD · Air quality right now
The air quality index in Frederick, MD is 34 (Good) right now — safe for outdoor activity.
Is it safe to be outside in Frederick today?
AQI 34 Yes — air quality is Good
Air is clean — great for outdoor activity.Main pollutant: OzoneObserved 12:00 AM EDT
Pollutants right now
- PM2.53.1 µg/m³fine particles — smoke, exhaust, soot
- PM103.1 µg/m³coarse particles — dust, pollen, ash
- Ozone58 µg/m³Main pollutantsmog — builds on hot, sunny days
- NO₂7.1 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run — no air-quality limits on outdoor exercise.
How to read Frederick’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 Frederick
Across the EPA’s county records from 2020 to 2025, Frederick’s cleanest year was 2020 (median AQI 40) and its most polluted was 2023 (median AQI 44); the typical (median) day has trended more polluted since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 40 | 0 | Ozone | 0 | 20 | 217 |
| 2021 | 41 | 0 | Ozone | 1 | 36 | 207 |
| 2022 | 41 | 0 | Ozone | 1 | 23 | 212 |
| 2023 | 44 | 0 | Ozone | 6 | 59 | 167 |
| 2024 | 43 | 0 | Ozone | 0 | 51 | 192 |
| 2025 | 41 | 0 | Ozone | 0 | 34 | 203 |
“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 Frederick?
- In the EPA's 2020–2025 county records, 2023 had the most days above AQI 100: 6 days (6 Unhealthy for Sensitive Groups, 0 Unhealthy or worse). It also had the highest median AQI, 44.
- How many unhealthy air days does Frederick have?
- Across 2020–2025, under 1% of the days reported for Frederick's county had an AQI above 100 (8 of 1429), about 1 day a year. 2025 had 0 days.
- What's the main air pollutant in Frederick?
- Ozone: it drove Frederick's county AQI on the most days in every year of the EPA's 2020–2025 records.