# Counties in Virginia by share of days with good air quality (US EPA AQI), 1999

All 42 values come from U.S. Environmental Protection Agency for 1999, so the places are comparable. 18 counties have no value for that period and are not ranked.

- Indicator id: `aqi_good_days_share`
- Unit: %
- Definition: Days with a daily Air Quality Index of 0 to 50 (good) as a percentage of the days of the year with an AQI in a US county. Calculated by Invokely from the day counts in the EPA AirData annual summaries; both counts are stored with each value.
- Source: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts (https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual)
- Retrieved: 2026-10-12
- Citation: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
- Web page: https://invokely.ai/rankings/good-air-quality-days-share/virginia-counties

| Rank | Place | % |
|---:|---|---:|
| 1 | Carroll County | 100 |
| 1 | Charlottesville city | 100 |
| 1 | Culpeper County | 100 |
| 1 | Fredericksburg city | 100 |
| 1 | King William County | 100 |
| 1 | Northumberland County | 100 |
| 1 | Rockingham County | 100 |
| 1 | Tazewell County | 100 |
| 1 | Warren County | 100 |
| 1 | Winchester city | 100 |
| 1 | Wise County | 100 |
| 12 | Roanoke city | 81.9 |
| 13 | Norfolk city | 79.7 |
| 14 | Roanoke County | 77.9 |
| 15 | Newport News city | 72.8 |
| 16 | Prince William County | 70.7 |
| 17 | Caroline County | 69.9 |
| 18 | Alexandria city | 69 |
| 19 | Prince Edward County | 68.8 |
| 20 | Charles City County | 64.1 |
| 21 | Hampton city | 63.8 |
| 22 | Loudoun County | 63.2 |
| 23 | Arlington County | 55.3 |
| 24 | Frederick County | 53.1 |
| 25 | Chesterfield County | 51.3 |
| 26 | Giles County | 51.2 |
| 27 | Hanover County | 50.2 |
| 28 | Suffolk city | 49.5 |
| 29 | Madison County | 49.4 |
| 30 | Fauquier County | 49 |
| 31 | Stafford County | 48.1 |
| 32 | Page County | 47.7 |
| 33 | Henrico County | 45.6 |
| 34 | Virginia Beach city | 40.2 |
| 35 | Fairfax County | 39.2 |
| 36 | Chesapeake city | 37.5 |
| 37 | Richmond city | 36.2 |
| 38 | Wythe County | 35 |
| 39 | Rockbridge County | 33.6 |
| 40 | Salem city | 29.9 |
| 41 | Lynchburg city | 28.6 |
| 42 | Bristol city | 18.5 |