Data / Median Air Quality Index (US EPA) / Williamsburg County

Median Air Quality Index (US EPA) in Williamsburg County

Median Air Quality Index (US EPA) in Williamsburg County was 44 in 2007, according to the U.S. Environmental Protection Agency. That is up 4 from 2006. That is the 18th highest of 25 counties in 2007.

2007, index44
Change on 2006+4
Rank18th of 25Counties in South Carolina ranked
Series high451998
Series low351994

Next release: Tuesday, 13 July 2027, estimated by Invokely from past publication dates (low confidence), not announced by the publisher. Release calendar

Get an email when a new figure is out or this one is revised.
Keep it in a collection in your library.

Median Air Quality Index (US EPA) in Williamsburg County, 1991 to 2007

343638404244461991199419972000200320071991: 38 index1992: 37 index1993: 40 index1994: 35 index1995: 40 index1996: 40 index1997: 42 index1998: 45 index1999: 41 index2000: 45 index2001: 40 index2002: 41 index2003: 37 index2004: 37 index2005: 38 index2006: 40 index2007: 44 index3537.54042.5451991199720071991: 38 index1992: 37 index1993: 40 index1994: 35 index1995: 40 index1996: 40 index1997: 42 index1998: 45 index1999: 41 index2000: 45 index2001: 40 index2002: 41 index2003: 37 index2004: 37 index2005: 38 index2006: 40 index2007: 44 index
index. Source: EPA, EPA AirData annual AQI by county: median daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 17 values
Periodindex
200744
200640
200538
200437
200337
200241
200140
200045
199941
199845
199742
199640
199540
199435
199340
199237
199138

Williamsburg County compared with nearby places

Abbeville County: 51 indexAiken County: 42 indexBarnwell County: 40 indexBeaufort County: 50 indexBerkeley County: 36 indexCharleston County: 55 indexCherokee County: 39 indexChester County: 48 indexChesterfield County: 47 indexColleton County: 41 indexDarlington County: 47 indexEdgefield County: 44 indexFlorence County: 55 indexGeorgetown County: 26 indexGreenville County: 61 indexGreenwood County: 57 indexHorry County: 52 indexLexington County: 57 indexOconee County: 45 indexPickens County: 51 indexRichland County: 60 indexSpartanburg County: 59 indexUnion County: 50 indexWilliamsburg County: 44 indexYork County: 47 index
  • Under 42
  • 42 to 47
  • 47 to 50
  • 50 to 55
  • 55 and over
  • No data
Median Air Quality Index (US EPA), 2007, index. Williamsburg County is outlined. Same source and period for every area shown. Source: U.S. Environmental Protection Agency. Boundaries: U.S. Census Bureau cartographic boundary files.

Rankings

Definition

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.

Report a problem with this figure

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 (Median Air Quality Index (US EPA), Williamsburg County, 1991 to 2007) [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, Median Air Quality Index (US EPA), Williamsburg County, 1991 to 2007. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/median-air-quality-index/williamsburg-county-south-carolina. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: median daily AQI. Median Air Quality Index (US EPA), Williamsburg County, 1991 to 2007. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/median-air-quality-index/williamsburg-county-south-carolina.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: median daily AQI, Median Air Quality Index (US EPA), Williamsburg County, 1991 to 2007 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/median-air-quality-index/williamsburg-county-south-carolina (Accessed: 12 October 2026).

BibTeX
@misc{environmental_median_air_quality_index_2007,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: median daily AQI: Median Air Quality Index (US EPA), Williamsburg County, 1991 to 2007}},
  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/en/median-air-quality-index/williamsburg-county-south-carolina. 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: Median Air Quality Index (US EPA), Williamsburg County, 1991 to 2007
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/en/median-air-quality-index/williamsburg-county-south-carolina
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/median-air-quality-index/williamsburg-county-south-carolina.
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  -
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:

What is the latest median Air Quality Index (US EPA) in Williamsburg County? Cite the source.
get_value {"indicator":"aqi_median","place":"us-county-45089"}
GET https://invokely.ai/api/v1/value?indicator=aqi_median&place=us-county-45089

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

Questions

What is the median Air Quality Index (US EPA) in Williamsburg County?

Median Air Quality Index (US EPA) in Williamsburg County was 44 in 2007, according to the U.S. Environmental Protection Agency. That is up 4 from 2006. That is the 18th highest of 25 counties in 2007.

Where does this figure come from?

U.S. Environmental Protection Agency. EPA AirData annual AQI by county: median daily AQI. Retrieved by Invokely on 2026-10-12.

What was the highest median Air Quality Index (US EPA) in Williamsburg County?

45 in 1998, the highest value since 1991 in this series.

Related statistics for Williamsburg County

All statistics for Williamsburg County | Williamsburg County in figures