Counties in Virginia by highest daily Air Quality Index (US EPA)

Fairfax County had the highest highest daily Air Quality Index (US EPA) of 42 counties in 1996, at 200. Warren County had the lowest, at 36. The median was 107. Source: the U.S. Environmental Protection Agency.

Highest200Fairfax County

Lowest36Warren County

Median10742 counties

Map of counties, 1996

Under 46
46 to 56
56 to 110
110 to 150
150 to 160
160 and over
No data

index, 1996. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 1996

index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12.

Full ranking

Rank	Counties	1996 index	Change on 1995
1	Fairfax County	200	-18
2	Stafford County	174	-11
3	Caroline County	166	+2
4	Alexandria city	164	-44
4	Charles City County	164	-5
6	Fauquier County	161	+10
7	Henry County	159	-10
7	Prince William County	159	-49
9	Chesterfield County	156	-36
9	Hampton city	156	+5
11	Henrico County	154	-47
11	Madison County	154	-15
13	Arlington County	151	-62
13	Suffolk city	151	-49
15	Frederick County	150	-16
15	Giles County	150	-22
17	Hanover County	143	-60
18	Prince Edward County	133	-39
19	Wythe County	126	-35
20	Roanoke County	119	-35
21	Rockbridge County	115	-24
22	Richmond city	98	-9
23	Roanoke city	78	+6
24	Norfolk city	76	-10
25	Smyth County	63	+6
26	King William County	57	+14
27	Tazewell County	56	+12
27	Wise County	56	+4
29	Bristol city	55	0
29	Carroll County	55	+4
31	Covington city	54	+6
31	Fredericksburg city	54	+5
31	Loudoun County	54	+11
34	Martinsville city	47	-10
35	Northumberland County	46	+4
36	Newport News city	45	+6
37	Chesapeake city	44	+7
38	Lynchburg city	43	-8
39	Winchester city	42	-4
40	Culpeper County	40	-9
41	Charlottesville city	36	-16
41	Warren County	36	-9

Other periods

About this ranking

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. United States counties with air quality monitors only, about 1,000 of some 3,100 in recent years; a county without monitors has no value. The number of days with an AQI differs between counties because some monitors run only in the ozone season.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. 18 counties with data in other periods have no value for 1996 and are left out rather than filled from another source. Equal values share a rank.

How to cite

U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Environmental Protection Agency. (2026). EPA AirData annual AQI by county: highest daily AQI (Counties in Virginia by highest daily Air Quality Index (US EPA), 1996) [Data set]. Retrieved October 12, 2026, from https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual

MLA 9

EPA AirData annual AQI by county: highest daily AQI, Counties in Virginia by highest daily Air Quality Index (US EPA), 1996. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties?period=1996. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in Virginia by highest daily Air Quality Index (US EPA), 1996. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties?period=1996.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in Virginia by highest daily Air Quality Index (US EPA), 1996 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties?period=1996 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_virginia_by_1996,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in Virginia by highest daily Air Quality Index (US EPA), 1996}},
  year = {2026},
  howpublished = {Data set},
  url = {https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties?period=1996. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download\_files.html\#Annual. Retrieved 2026-10-12.},
}

RIS

TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: highest daily AQI: Counties in Virginia by highest daily Air Quality Index (US EPA), 1996
PY  - 2026
DA  - 2026/07/13
PB  - U.S. Environmental Protection Agency
DB  - Invokely
UR  - https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual
L2  - https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties?period=1996
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/virginia-counties?period=1996.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest daily AQI. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Retrieved 2026-10-12.
ER  -

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Questions

Which county has the highest highest daily Air Quality Index (US EPA)?

Fairfax County, with 200 in 1996, according to the U.S. Environmental Protection Agency.

Which county has the lowest highest daily Air Quality Index (US EPA)?

Warren County, with 36 in 1996.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Environmental Protection Agency, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12. 18 counties have no value for 1996 and are not ranked.