# Solano County, California annual air quality

In the 2025 EPA annual record, Solano County had a median AQI of 33 (Good) and 99.2% of 356 monitored days were rated Good.

## Key figures

- Monitored days: 356
- Good days: 353 (99.2%)
- Moderate days: 3
- Unhealthy for Sensitive Groups days: 0
- Unhealthy-or-worse days: 0
- Median AQI: 33 (Good)
- 90th-percentile AQI: 42
- Maximum AQI: 61 (Moderate)
- Main pollutant-day driver: ozone

The Good-day percentage uses monitored days as its denominator; unmonitored calendar days are not estimated. This record clears the 100-day comparison floor.

## Annual history

- 2020: median AQI 51; 50.0% Good (183 of 366 monitored days).
- 2021: median AQI 44; 58.9% Good (215 of 365 monitored days).
- 2022: median AQI 43; 64.4% Good (235 of 365 monitored days).
- 2023: median AQI 40; 73.7% Good (269 of 365 monitored days).
- 2024: median AQI 36; 94.0% Good (343 of 365 monitored days).
- 2025: median AQI 33; 99.2% Good (353 of 356 monitored days).

## Source and scope

- Source: U.S. EPA Air Quality System annual summary for 2025: https://aqs.epa.gov/aqsweb/airdata/download_files.html
- PlainAirData data refresh: 2026-08-23
- Scope: annual monitor records, not current conditions or an air-quality forecast.
- Methodology: https://plainairdata.com/methodology

## Related resources

- Full HTML page: https://plainairdata.com/county/california-solano
- County CSV row: https://plainairdata.com/county/california-solano.csv
- State overview: https://plainairdata.com/state/california