Merced, California Air Quality
Merced air quality today — the AQI, the main pollutant, and whether it’s safe to exercise outside right now
Merced, CA · Air quality right now
The air quality index in Merced, CA is 70 (Moderate) right now — acceptable for most people.
Is it safe to be outside in Merced today?
AQI 70 Yes — air quality is Moderate
Fine for most; unusually sensitive people can take it easy.Main pollutant: PM2.5Observed 8:00 AM PDT
Pollutants right now
- PM2.521 µg/m³Main pollutantfine particles — smoke, exhaust, soot
- PM1034 µg/m³coarse particles — dust, pollen, ash
- Ozone28 µg/m³smog — builds on hot, sunny days
- NO₂11 µg/m³nitrogen dioxide — traffic, combustion
ExerciseOK to run for most; sensitive athletes can ease the intensity.
How to read Merced’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 Merced
Across the EPA’s county records from 2020 to 2025, Merced’s cleanest year was 2025 (median AQI 50) and its most polluted was 2020 (median AQI 57); the typical (median) day has trended cleaner since 2020.
| Year | Median AQI | Unhealthy+ | Main pollutant | USG | Moderate | Good |
|---|---|---|---|---|---|---|
| 2020 | 57 | 15 | PM2.5 | 17 | 203 | 131 |
| 2021 | 54 | 2 | Ozone | 31 | 177 | 155 |
| 2022 | 56 | 0 | Ozone | 13 | 212 | 140 |
| 2023 | 51 | 0 | Ozone | 15 | 179 | 171 |
| 2024 | 52 | 1 | Ozone | 34 | 163 | 168 |
| 2025 | 50 | 0 | Ozone | 0 | 179 | 186 |
“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 Merced?
- In the EPA's 2020–2025 county records, 2024 had the most days above AQI 100: 35 days (34 Unhealthy for Sensitive Groups, 1 Unhealthy or worse). The highest median AQI came in 2020 (57; 2024's was 52).
- How many unhealthy air days does Merced have?
- Across 2020–2025, 6% of the days reported for Merced's county had an AQI above 100 (128 of 2192), about 21 days a year. 2025 had 0 days.
- What's the main air pollutant in Merced?
- Ozone drove Merced's county AQI on the most days in 5 of 6 years (2020–2025); PM2.5 in 2020.