Data / Rankings / Share of days with good air quality (US EPA AQI) / Counties in South Carolina

Counties in South Carolina by share of days with good air quality (US EPA AQI)

Fairfield County had the highest share of days with good air quality (US EPA AQI) of 25 counties in 1999, at 100%. Greenwood County had the lowest, at 20.6%. The median was 47.5%. Source: EPA.

Keep it in a collection in your library.
Highest100Fairfield County
Lowest20.6Greenwood County
Median47.525 counties

Map of counties, 1999

Abbeville County: 47.5 %Aiken County: 73.1 %Anderson County: 60.7 %Barnwell County: 73.4 %Beaufort County: 33.3 %Berkeley County: 76.1 %Charleston County: 29.9 %Cherokee County: 56.8 %Chester County: 44.6 %Colleton County: 47.3 %Darlington County: 66.6 %Edgefield County: 59.6 %Fairfield County: 100 %Florence County: 27.7 %Georgetown County: 72 %Greenville County: 47.4 %Greenwood County: 20.6 %Lexington County: 41.1 %Oconee County: 53.5 %Pickens County: 36.1 %Richland County: 42.7 %Spartanburg County: 23 %Union County: 70.3 %Williamsburg County: 70.8 %York County: 43.4 %
  • Under 36
  • 36 to 46
  • 46 to 58
  • 58 to 71
  • 71 and over
  • No data
%, 1999. 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, 1999

Fairfield County: 100 %Fairfield County100Berkeley County: 76.1 %Berkeley County76.1Barnwell County: 73.4 %Barnwell County73.4Aiken County: 73.1 %Aiken County73.1Georgetown County: 72 %Georgetown County72Williamsburg County: 70.8 %Williamsburg County70.8Union County: 70.3 %Union County70.3Darlington County: 66.6 %Darlington County66.6Anderson County: 60.7 %Anderson County60.7Edgefield County: 59.6 %Edgefield County59.6Cherokee County: 56.8 %Cherokee County56.8Oconee County: 53.5 %Oconee County53.5Abbeville County: 47.5 %Abbeville County47.5Greenville County: 47.4 %Greenville County47.4Colleton County: 47.3 %Colleton County47.3Chester County: 44.6 %Chester County44.6York County: 43.4 %York County43.4Richland County: 42.7 %Richland County42.7Lexington County: 41.1 %Lexington County41.1Pickens County: 36.1 %Pickens County36.1Beaufort County: 33.3 %Beaufort County33.3Charleston County: 29.9 %Charleston County29.9Florence County: 27.7 %Florence County27.7Spartanburg County: 23 %Spartanburg County23Greenwood County: 20.6 %Greenwood County20.6Fairfield County: 100 %Fairfield County100Berkeley County: 76.1 %Berkeley County76.1Barnwell County: 73.4 %Barnwell County73.4Aiken County: 73.1 %Aiken County73.1Georgetown County: 72 %Georgetown County72Williamsburg County: 70.8 %Williamsburg County70.8Union County: 70.3 %Union County70.3Darlington County: 66.6 %Darlington County66.6Anderson County: 60.7 %Anderson County60.7Edgefield County: 59.6 %Edgefield County59.6Cherokee County: 56.8 %Cherokee County56.8Oconee County: 53.5 %Oconee County53.5Abbeville County: 47.5 %Abbeville County47.5Greenville County: 47.4 %Greenville County47.4Colleton County: 47.3 %Colleton County47.3Chester County: 44.6 %Chester County44.6York County: 43.4 %York County43.4Richland County: 42.7 %Richland County42.7Lexington County: 41.1 %Lexington County41.1Pickens County: 36.1 %Pickens County36.1Beaufort County: 33.3 %Beaufort County33.3Charleston County: 29.9 %Charleston County29.9Florence County: 27.7 %Florence County27.7Spartanburg County: 23 %Spartanburg County23Greenwood County: 20.6 %Greenwood County20.6
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties1999 (%)Change on 1998
1Fairfield County100+1.7 pts
2Berkeley County76.1+2.1 pts
3Barnwell County73.4+8.8 pts
4Aiken County73.1+8.3 pts
5Georgetown County72-19.2 pts
6Williamsburg County70.8+4.9 pts
7Union County70.3+0.6 pts
8Darlington County66.6+2.6 pts
9Anderson County60.7+0.1 pts
10Edgefield County59.6-1.5 pts
11Cherokee County56.8+10.9 pts
12Oconee County53.5-18.4 pts
13Abbeville County47.5+2.7 pts
14Greenville County47.4-46.5 pts
15Colleton County47.3-4.8 pts
16Chester County44.6+1.3 pts
17York County43.4-13.4 pts
18Richland County42.7-6.1 pts
19Lexington County41.1-28.3 pts
20Pickens County36.1-25.2 pts
21Beaufort County33.3n/a
22Charleston County29.9-44.9 pts
23Florence County27.7n/a
24Spartanburg County23-45.8 pts
25Greenwood County20.6n/a

Other periods

About this ranking

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.

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 1999 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: 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 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: good days as a share of days with an AQI, calculated with stored counts (Counties in South Carolina by share of days with good air quality (US EPA AQI), 1999) [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: good days as a share of days with an AQI, calculated with stored counts, Counties in South Carolina by share of days with good air quality (US EPA AQI), 1999. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/good-air-quality-days-share/south-carolina-counties?period=1999. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts. Counties in South Carolina by share of days with good air quality (US EPA AQI), 1999. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/good-air-quality-days-share/south-carolina-counties?period=1999.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts, Counties in South Carolina by share of days with good air quality (US EPA AQI), 1999 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/good-air-quality-days-share/south-carolina-counties?period=1999 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_south_carolina_1999,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in South Carolina by share of days with good air quality (US EPA AQI), 1999}},
  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/good-air-quality-days-share/south-carolina-counties?period=1999. Publisher attribution: 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.},
}
RIS
TY  - DATA
AU  - U.S. Environmental Protection Agency
TI  - EPA AirData annual AQI by county: good days as a share of days with an AQI, calculated with stored counts: Counties in South Carolina by share of days with good air quality (US EPA AQI), 1999
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/good-air-quality-days-share/south-carolina-counties?period=1999
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/good-air-quality-days-share/south-carolina-counties?period=1999.
N1  - Publisher attribution: 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.
ER  -
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Questions

Which county has the highest share of days with good air quality (US EPA AQI)?

Fairfield County, with 100% in 1999, according to EPA.

Which county has the lowest share of days with good air quality (US EPA AQI)?

Greenwood County, with 20.6% in 1999.

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: good days as a share of days with an AQI, calculated with stored counts. Retrieved 2026-10-12. 3 counties have no value for 1999 and are not ranked.

Share of days with good air quality (US EPA AQI): other rankings

Counties in South Carolina: more rankings