Highest daily Air Quality Index (US EPA) in Horry County

Highest daily Air Quality Index (US EPA) in Horry County was 170 in 2025, according to the U.S. Environmental Protection Agency. That is up 83 from 2024.

2025, index170
Change on 2024+83
Series high2001983
Series low392016

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

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Highest daily Air Quality Index (US EPA) in Horry County, 1980 to 2025

05010015020019802000200420092017202120251980: 159 index1981: 172 index1982: 164 index1983: 200 index2000: 57 index2001: 90 index2002: 166 index2003: 87 index2004: 92 index2005: 121 index2006: 93 index2007: 129 index2009: 55 index2010: 101 index2011: 90 index2016: 39 index2017: 64 index2018: 87 index2019: 77 index2020: 50 index2021: 90 index2022: 93 index2023: 100 index2024: 87 index2025: 170 index0501001502001980200520251980: 159 index1981: 172 index1982: 164 index1983: 200 index2000: 57 index2001: 90 index2002: 166 index2003: 87 index2004: 92 index2005: 121 index2006: 93 index2007: 129 index2009: 55 index2010: 101 index2011: 90 index2016: 39 index2017: 64 index2018: 87 index2019: 77 index2020: 50 index2021: 90 index2022: 93 index2023: 100 index2024: 87 index2025: 170 index
index. Source: EPA, EPA AirData annual AQI by county: highest daily AQI. Retrieved 2026-10-12, published 2026-07-13.
All 25 values
Periodindex
2025170
202487
2023100
202293
202190
202050
201977
201887
201764
201639
201190
2010101
200955
2007129
200693
2005121
200492
200387
2002166
200190
200057
1983200
1982164
1981172
1980159

Horry County compared with nearby places

Aiken County: 71 indexAnderson County: 84 indexBerkeley County: 84 indexCharleston County: 105 indexChesterfield County: 103 indexDarlington County: 97 indexEdgefield County: 98 indexFlorence County: 108 indexGreenville County: 93 indexHorry County: 170 indexRichland County: 89 indexSpartanburg County: 93 indexYork County: 93 index
  • Under 86
  • 86 to 93
  • 93 to 97
  • 97 to 100
  • 100 and over
  • No data
Highest daily Air Quality Index (US EPA), 2025, index. Horry 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

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.

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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 (Highest daily Air Quality Index (US EPA), Horry County, 1980 to 2025) [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, Highest daily Air Quality Index (US EPA), Horry County, 1980 to 2025. U.S. Environmental Protection Agency, 13 July 2026, https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Invokely, https://invokely.ai/en/highest-daily-air-quality-index/horry-county-south-carolina. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Environmental Protection Agency. 2026. EPA AirData annual AQI by county: highest daily AQI. Highest daily Air Quality Index (US EPA), Horry County, 1980 to 2025. Dataset. Accessed October 12, 2026. https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual. Also distributed by Invokely, https://invokely.ai/en/highest-daily-air-quality-index/horry-county-south-carolina.

Harvard

U.S. Environmental Protection Agency (2026) EPA AirData annual AQI by county: highest daily AQI, Highest daily Air Quality Index (US EPA), Horry County, 1980 to 2025 [Dataset]. Available at: https://aqs.epa.gov/aqsweb/airdata/download_files.html#Annual, via Invokely: https://invokely.ai/en/highest-daily-air-quality-index/horry-county-south-carolina (Accessed: 12 October 2026).

BibTeX
@misc{environmental_highest_daily_air_quality_2025,
  author = {{U.S. Environmental Protection Agency}},
  title = {{EPA AirData annual AQI by county: highest daily AQI: Highest daily Air Quality Index (US EPA), Horry County, 1980 to 2025}},
  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/highest-daily-air-quality-index/horry-county-south-carolina. 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: Highest daily Air Quality Index (US EPA), Horry County, 1980 to 2025
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/highest-daily-air-quality-index/horry-county-south-carolina
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/en/highest-daily-air-quality-index/horry-county-south-carolina.
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

What is the highest daily Air Quality Index (US EPA) in Horry County?

Highest daily Air Quality Index (US EPA) in Horry County was 170 in 2025, according to the U.S. Environmental Protection Agency. That is up 83 from 2024.

Where does this figure come from?

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

What was the highest highest daily Air Quality Index (US EPA) in Horry County?

200 in 1983, the highest value since 1980 in this series.

Related statistics for Horry County

All statistics for Horry County | Horry County in figures