Data / Rankings / Median Air Quality Index (US EPA) / Counties in West Virginia

Counties in West Virginia by median Air Quality Index (US EPA), 2005

Marshall County had the highest median Air Quality Index (US EPA) of 18 counties in 2005, at 63. Brooke County had the lowest, at 28. The median was 53. Source: the U.S. Environmental Protection Agency.

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Highest63Marshall County
Lowest28Brooke County
Median5318 counties

Map of counties, 2005

Berkeley County: 54 indexBrooke County: 28 indexCabell County: 55 indexGilmer County: 31 indexGreenbrier County: 44 indexHancock County: 41 indexHarrison County: 59 indexKanawha County: 46 indexMarion County: 61 indexMarshall County: 63 indexMercer County: 57 indexMonongalia County: 52 indexOhio County: 57 indexRaleigh County: 55 indexSummers County: 52 indexTucker County: 39 indexWayne County: 33 indexWood County: 54 index
  • Under 40
  • 40 to 51
  • 51 to 54
  • 54 to 57
  • 57 and over
  • No data
index, 2005. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2005

Marshall County: 63 indexMarshall County63Marion County: 61 indexMarion County61Harrison County: 59 indexHarrison County59Mercer County: 57 indexMercer County57Ohio County: 57 indexOhio County57Cabell County: 55 indexCabell County55Raleigh County: 55 indexRaleigh County55Berkeley County: 54 indexBerkeley County54Wood County: 54 indexWood County54Monongalia County: 52 indexMonongalia County52Summers County: 52 indexSummers County52Kanawha County: 46 indexKanawha County46Greenbrier County: 44 indexGreenbrier County44Hancock County: 41 indexHancock County41Tucker County: 39 indexTucker County39Wayne County: 33 indexWayne County33Gilmer County: 31 indexGilmer County31Brooke County: 28 indexBrooke County28Marshall County: 63 indexMarshall County63Marion County: 61 indexMarion County61Harrison County: 59 indexHarrison County59Mercer County: 57 indexMercer County57Ohio County: 57 indexOhio County57Cabell County: 55 indexCabell County55Raleigh County: 55 indexRaleigh County55Berkeley County: 54 indexBerkeley County54Wood County: 54 indexWood County54Monongalia County: 52 indexMonongalia County52Summers County: 52 indexSummers County52Kanawha County: 46 indexKanawha County46Greenbrier County: 44 indexGreenbrier County44Hancock County: 41 indexHancock County41Tucker County: 39 indexTucker County39Wayne County: 33 indexWayne County33Gilmer County: 31 indexGilmer County31Brooke County: 28 indexBrooke County28
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12.

Full ranking

RankCounties2005
index		Change on 2004
1Marshall County63+4
2Marion County61+2
3Harrison County59+3
4Mercer County57+3
4Ohio County57+19
6Cabell County55+5
6Raleigh County550
8Berkeley County54+6
8Wood County54+3
10Monongalia County52+5
10Summers County52+8
12Kanawha County46+5
13Greenbrier County44+3
14Hancock County41+1
15Tucker County39+2
16Wayne County330
17Gilmer County310
18Brooke County28-7

Other periods

About this ranking

Median of the daily Air Quality Index (AQI) values of a US county over the days of the year with an AQI, from the EPA AirData annual summaries.

More on how it is measured
  • The daily county AQI is the highest AQI among the monitors and pollutants reported that day (ozone, PM2.5, PM10, carbon monoxide and nitrogen dioxide).
  • Lower is cleaner: 0 to 50 is good, 51 to 100 moderate and above 100 unhealthy for sensitive groups.

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. 2 counties with data in other periods have no value for 2005 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: median 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: median daily AQI (Counties in West Virginia by median Air Quality Index (US EPA), 2005) [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: median daily AQI, Counties in West Virginia by median Air Quality Index (US EPA), 2005. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/median-air-quality-index/west-virginia-counties. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Counties in West Virginia by median Air Quality Index (US EPA), 2005. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/median-air-quality-index/west-virginia-counties.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Counties in West Virginia by median Air Quality Index (US EPA), 2005 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/median-air-quality-index/west-virginia-counties (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_west_virginia_2005,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Counties in West Virginia by median Air Quality Index (US EPA), 2005}},
  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/median-air-quality-index/west-virginia-counties. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median 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: median daily AQI: Counties in West Virginia by median Air Quality Index (US EPA), 2005
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/median-air-quality-index/west-virginia-counties
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/median-air-quality-index/west-virginia-counties.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: median 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 median Air Quality Index (US EPA)?

Marshall County, with 63 in 2005, according to the U.S. Environmental Protection Agency.

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

Brooke County, with 28 in 2005.

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: median daily AQI. Retrieved 2026-10-12. 2 counties have no value for 2005 and are not ranked.

Median Air Quality Index (US EPA): other rankings

Counties in West Virginia: more rankings