Counties in South Carolina by highest daily Air Quality Index (US EPA)

Richland County had the highest highest daily Air Quality Index (US EPA) of 26 counties in 2006, at 278. Beaufort County had the lowest, at 82. The median was 136. Source: the U.S. Environmental Protection Agency.

Highest278Richland County

Lowest82Beaufort County

Median13626 counties

Map of counties, 2006

Under 97
97 to 130
130 to 140
140 to 160
160 and over
No data

index, 2006. Hatched areas have no value for this period. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2006

index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2006 index	Change on 2005
1	Richland County	278	+101
2	Spartanburg County	172	+21
3	Abbeville County	166	+12
3	York County	166	+15
5	Pickens County	164	+5
6	Greenville County	162	+8
7	Cherokee County	161	+21
8	Chesterfield County	160	+17
9	Charleston County	159	+19
10	Chester County	151	-13
11	Anderson County	143	-4
12	Colleton County	136	+10
12	Union County	136	-14
12	Williamsburg County	136	+31
15	Barnwell County	126	+11
15	Darlington County	126	-25
17	Berkeley County	119	-7
18	Aiken County	115	-25
19	Edgefield County	105	-35
20	Georgetown County	99	-18
21	Lexington County	97	-11
22	Florence County	96	-9
22	Oconee County	96	-60
24	Greenwood County	94	-13
25	Horry County	93	-28
26	Beaufort County	82	-35

Other periods

About this ranking

Highest daily Air Quality Index (AQI) value recorded in a US county during the year, from the EPA AirData annual summaries. Values above 500 are beyond the AQI scale and are published as EPA computes them.

A single day decides the value, so one wildfire or dust event can set it. Dust from the dry Owens Lake bed puts Inyo and Mono counties in California in the thousands. 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 2006 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: highest 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: highest daily AQI (Counties in South Carolina by highest daily Air Quality Index (US EPA), 2006) [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: highest daily AQI, Counties in South Carolina by highest daily Air Quality Index (US EPA), 2006. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/south-carolina-counties?period=2006. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Counties in South Carolina by highest daily Air Quality Index (US EPA), 2006. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/south-carolina-counties?period=2006.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Counties in South Carolina by highest daily Air Quality Index (US EPA), 2006 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/rankings/highest-daily-air-quality-index/south-carolina-counties?period=2006 (Accessed: 12 October 2026).

BibTeX

@misc{environmental_counties_in_south_carolina_2006,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Counties in South Carolina by highest daily Air Quality Index (US EPA), 2006}},
  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/highest-daily-air-quality-index/south-carolina-counties?period=2006. Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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: highest daily AQI: Counties in South Carolina by highest daily Air Quality Index (US EPA), 2006
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/highest-daily-air-quality-index/south-carolina-counties?period=2006
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/highest-daily-air-quality-index/south-carolina-counties?period=2006.
N1  - Publisher attribution: U.S. Environmental Protection Agency, Air Quality System, AirData. EPA AirData annual AQI by county: highest 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 highest daily Air Quality Index (US EPA)?

Richland County, with 278 in 2006, according to the U.S. Environmental Protection Agency.

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

Beaufort County, with 82 in 2006.

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: highest daily AQI. Retrieved 2026-10-12. 2 counties have no value for 2006 and are not ranked.