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

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

Anderson County had the highest share of days unhealthy for sensitive groups or worse (US EPA AQI) of 27 counties in 2002, at 20.9%. Orangeburg County had the lowest, at 0%. The median was 8%. Source: EPA.

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Highest20.9Anderson County
Lowest0Orangeburg County
Median827 counties

Map of counties, 2002

Abbeville County: 15.7 %Aiken County: 8.2 %Anderson County: 20.9 %Barnwell County: 5.5 %Beaufort County: 0 %Berkeley County: 2.8 %Charleston County: 2.5 %Cherokee County: 11.3 %Chester County: 19.5 %Chesterfield County: 12.3 %Colleton County: 5.4 %Darlington County: 9.5 %Edgefield County: 8 %Florence County: 0 %Georgetown County: 0 %Greenville County: 1.1 %Greenwood County: 0.9 %Horry County: 0.9 %Lexington County: 0.3 %Oconee County: 8.8 %Orangeburg County: 0 %Pickens County: 18.7 %Richland County: 12.3 %Spartanburg County: 15.6 %Union County: 15.1 %Williamsburg County: 4.4 %York County: 16.1 %
  • Under 0.9
  • 0.9 to 4.8
  • 4.8 to 9.2
  • 9.2 to 16
  • 16 and over
  • No data
%, 2002. 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, 2002

Anderson County: 20.9 %Anderson County20.9Chester County: 19.5 %Chester County19.5Pickens County: 18.7 %Pickens County18.7York County: 16.1 %York County16.1Abbeville County: 15.7 %Abbeville County15.7Spartanburg County: 15.6 %Spartanburg County15.6Union County: 15.1 %Union County15.1Chesterfield County: 12.3 %Chesterfield County12.3Richland County: 12.3 %Richland County12.3Cherokee County: 11.3 %Cherokee County11.3Darlington County: 9.5 %Darlington County9.5Oconee County: 8.8 %Oconee County8.8Aiken County: 8.2 %Aiken County8.2Edgefield County: 8 %Edgefield County8Barnwell County: 5.5 %Barnwell County5.5Colleton County: 5.4 %Colleton County5.4Williamsburg County: 4.4 %Williamsburg County4.4Berkeley County: 2.8 %Berkeley County2.8Charleston County: 2.5 %Charleston County2.5Greenville County: 1.1 %Greenville County1.1Greenwood County: 0.9 %Greenwood County0.9Horry County: 0.9 %Horry County0.9Lexington County: 0.3 %Lexington County0.3Beaufort County: 0 %Beaufort County0Florence County: 0 %Florence County0Georgetown County: 0 %Georgetown County0Orangeburg County: 0 %Orangeburg County0Anderson County: 20.9 %Anderson County20.9Chester County: 19.5 %Chester County19.5Pickens County: 18.7 %Pickens County18.7York County: 16.1 %York County16.1Abbeville County: 15.7 %Abbeville County15.7Spartanburg County: 15.6 %Spartanburg County15.6Union County: 15.1 %Union County15.1Chesterfield County: 12.3 %Chesterfield County12.3Richland County: 12.3 %Richland County12.3Cherokee County: 11.3 %Cherokee County11.3Darlington County: 9.5 %Darlington County9.5Oconee County: 8.8 %Oconee County8.8Aiken County: 8.2 %Aiken County8.2Edgefield County: 8 %Edgefield County8Barnwell County: 5.5 %Barnwell County5.5Colleton County: 5.4 %Colleton County5.4Williamsburg County: 4.4 %Williamsburg County4.4Berkeley County: 2.8 %Berkeley County2.8Charleston County: 2.5 %Charleston County2.5Greenville County: 1.1 %Greenville County1.1Greenwood County: 0.9 %Greenwood County0.9Horry County: 0.9 %Horry County0.9Lexington County: 0.3 %Lexington County0.3Beaufort County: 0 %Beaufort County0Florence County: 0 %Florence County0Georgetown County: 0 %Georgetown County0Orangeburg County: 0 %Orangeburg County0
%. Source: Invokely calculation with data from EPA. Retrieved 2026-10-12.

Full ranking

RankCounties2002 (%)Change on 2001
1Anderson County20.9+4.9 pts
2Chester County19.5+5.5 pts
3Pickens County18.7+3.9 pts
4York County16.1+8.6 pts
5Abbeville County15.7+2.5 pts
6Spartanburg County15.6+7.5 pts
7Union County15.1+6.3 pts
8Chesterfield County12.3+12.3 pts
8Richland County12.3-1.1 pts
10Cherokee County11.3+4.7 pts
11Darlington County9.5+0.1 pts
12Oconee County8.8+2.2 pts
13Aiken County8.2-2.2 pts
14Edgefield County8+4 pts
15Barnwell County5.5+3.2 pts
16Colleton County5.4-0.2 pts
17Williamsburg County4.4+4 pts
18Berkeley County2.8+1.4 pts
19Charleston County2.5+1.7 pts
20Greenville County1.1-0.5 pts
21Greenwood County0.9+0.9 pts
21Horry County0.9+0.9 pts
23Lexington County0.3+0.3 pts
24Beaufort County00 pts
24Florence County00 pts
24Georgetown County00 pts
24Orangeburg County0n/a

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. 1 counties with data in other periods have no value for 2002 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 South Carolina by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2002) [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 South Carolina by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2002. 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/south-carolina-counties?period=2002. 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 South Carolina by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2002. 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/south-carolina-counties?period=2002.

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 South Carolina by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2002 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/unhealthy-air-quality-days-share/south-carolina-counties?period=2002 (Accessed: 12 October 2026).

BibTeX
@misc{environmental_counties_in_south_carolina_2002,
  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 South Carolina by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2002}},
  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/south-carolina-counties?period=2002. 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 South Carolina by share of days unhealthy for sensitive groups or worse (US EPA AQI), 2002
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/south-carolina-counties?period=2002
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/unhealthy-air-quality-days-share/south-carolina-counties?period=2002.
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  -
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Questions

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

Anderson County, with 20.9% in 2002, according to EPA.

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

Orangeburg County, with 0% in 2002.

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. 1 counties have no value for 2002 and are not ranked.

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

Counties in South Carolina: more rankings