Data / Rankings / Share of days unhealthy for sensitive groups or worse (US EPA AQI) / Counties in West Virginia

Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI)

Wood County had the highest share of days unhealthy for sensitive groups or worse (US EPA AQI) of 17 counties in 2001, at 11.9%. Summers County had the lowest, at 0.9%. The median was 3.8%. Source: EPA.

Keep it in a collection in your library.
Highest11.9Wood County
Lowest0.9Summers County
Median3.817 counties

Map of counties, 2001

Berkeley County: 8.3 %Brooke County: 2.2 %Cabell County: 11.8 %Gilmer County: 3.2 %Greenbrier County: 6.6 %Hancock County: 8.5 %Harrison County: 2.5 %Kanawha County: 10.6 %Marion County: 3.6 %Marshall County: 3.3 %Mercer County: 2.6 %Monongalia County: 4.7 %Ohio County: 10.1 %Raleigh County: 1.7 %Summers County: 0.9 %Tucker County: 3.8 %Wood County: 11.9 %
  • Under 2.5
  • 2.5 to 3.4
  • 3.4 to 5.8
  • 5.8 to 9.8
  • 9.8 and over
  • No data
%, 2001. Hatched areas have no value for this period. Source: Invokely calculation with data from EPA. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2001

Wood County: 11.9 %Wood County11.9Cabell County: 11.8 %Cabell County11.8Kanawha County: 10.6 %Kanawha County10.6Ohio County: 10.1 %Ohio County10.1Hancock County: 8.5 %Hancock County8.5Berkeley County: 8.3 %Berkeley County8.3Greenbrier County: 6.6 %Greenbrier County6.6Monongalia County: 4.7 %Monongalia County4.7Tucker County: 3.8 %Tucker County3.8Marion County: 3.6 %Marion County3.6Marshall County: 3.3 %Marshall County3.3Gilmer County: 3.2 %Gilmer County3.2Mercer County: 2.6 %Mercer County2.6Harrison County: 2.5 %Harrison County2.5Brooke County: 2.2 %Brooke County2.2Raleigh County: 1.7 %Raleigh County1.7Summers County: 0.9 %Summers County0.9Wood County: 11.9 %Wood County11.9Cabell County: 11.8 %Cabell County11.8Kanawha County: 10.6 %Kanawha County10.6Ohio County: 10.1 %Ohio County10.1Hancock County: 8.5 %Hancock County8.5Berkeley County: 8.3 %Berkeley County8.3Greenbrier County: 6.6 %Greenbrier County6.6Monongalia County: 4.7 %Monongalia County4.7Tucker County: 3.8 %Tucker County3.8Marion County: 3.6 %Marion County3.6Marshall County: 3.3 %Marshall County3.3Gilmer County: 3.2 %Gilmer County3.2Mercer County: 2.6 %Mercer County2.6Harrison County: 2.5 %Harrison County2.5Brooke County: 2.2 %Brooke County2.2Raleigh County: 1.7 %Raleigh County1.7Summers County: 0.9 %Summers County0.9
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2001 (%)Change on 2000
1Wood County11.9+3.5 pts
2Cabell County11.8+3.8 pts
3Kanawha County10.6+3.3 pts
4Ohio County10.1+7.9 pts
5Hancock County8.5+5.2 pts
6Berkeley County8.3+3.9 pts
7Greenbrier County6.6-3.8 pts
8Monongalia County4.7+0.3 pts
9Tucker County3.8+0.5 pts
10Marion County3.6+0.9 pts
11Marshall County3.3+1.5 pts
12Gilmer County3.2+0.9 pts
13Mercer County2.6+1.7 pts
14Harrison County2.5+1.6 pts
15Brooke County2.2+0.3 pts
16Raleigh County1.7+0.9 pts
17Summers County0.9+0.9 pts

Other periods

About this ranking

Days with a daily Air Quality Index above 100 (unhealthy for sensitive groups, unhealthy, very unhealthy or hazardous) 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; the counts are stored with each value.

Use the share rather than the number of days to compare counties, since the days with an AQI differ. 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. 3 counties with data in other periods have no value for 2001 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: days with an AQI above 100 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 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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts (Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2001) [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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2001. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/west-virginia-counties?period=2001. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2001. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/west-virginia-counties?period=2001.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts, Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2001 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/unhealthy-air-quality-days-share/west-virginia-counties?period=2001 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_west_virginia_2001,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2001}},
  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/unhealthy-air-quality-days-share/west-virginia-counties?period=2001. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts: Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2001
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/unhealthy-air-quality-days-share/west-virginia-counties?period=2001
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/west-virginia-counties?period=2001.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: days with an AQI above 100 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.
ER  -
Embed this chart

Paste this code into a web page or a blog post. The chart shows the latest figures as they are published, with the source and a link back to this page.

Sites that read oEmbed links, such as WordPress, can show the chart when you paste the link to this page.

Use this data in your AI agent

Invokely serves this figure to AI assistants through MCP and to code through a REST API, with the source and citation attached. Ask your assistant:

Rank Counties in West Virginia by share of days unhealthy for sensitive groups or worse (US EPA AQI) using official data, and cite the source.
rank_places {"indicator":"aqi_unhealthy_sensitive_or_worse_days_share","level":"province","within":"West Virginia","limit":10}
GET https://invokely.ai/api/v1/rank?indicator=aqi_unhealthy_sensitive_or_worse_days_share&level=province&within=West%20Virginia&limit=10

Connect Claude, ChatGPT or Cursor in one step. The trial answers 25 calls a day without an account.

Questions

Which county has the highest share of days unhealthy for sensitive groups or worse (US EPA AQI)?

Wood County, with 11.9% in 2001, according to EPA.

Which county has the lowest share of days unhealthy for sensitive groups or worse (US EPA AQI)?

Summers County, with 0.9% in 2001.

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: days with an AQI above 100 as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 3 counties have no value for 2001 and are not ranked.

Share of days unhealthy for sensitive groups or worse (US EPA AQI): other rankings

Counties in West Virginia: more rankings