State air quality · 2025

South Carolina Air Quality Ranking

Across 13 monitored counties, the typical county in South Carolina posts a median AQI of 43 (Good) and 71.3% of monitored days were rated Good, from EPA AQS.

43
Avg median AQI
71.3%
Good-air days
13
Counties monitored
23%
Cleaner than US states

South Carolina's typical county median AQI is 43 (Good) across 13 monitored counties

According to the U.S. EPA Air Quality System, South Carolina monitors 13 counties with a day-weighted Good-day share of 71.3%. Cleanest: Berkeley County (93.3% Good). Most polluted: Spartanburg County (55.1%). These are annual summaries, not live AirNow readings.

Data source EPA Air Quality System (AQS)

Cleaner than US states
South Carolina's day-weighted Good-day share of 71.3% places it cleaner than 23% of US states.
In-state spread
Within South Carolina, Berkeley County leads at 93.3% Good days while Spartanburg County sits at 55.1% across 13 monitored counties.
2024→2025 release
South Carolina's Good-day share moved +2.0 points vs the 2024 EPA annual release.
Typical median AQI
Typical median AQI: 43

Verify with AirNow → · EPA AQS →

EPA state monitoring brief

AQS state key SOUTH-CAROLINA

South Carolina · 2025 EPA AQS · 13 counties · med AQI 43 · 71.3% Good · Berkeley→Spartanburg spread

  • GOOD 43 Median AQI · Good
  • SHARE 71.3% Good-day share
  • COUNT 13 Counties monitored
  • UNH 2 Unhealthy+ days
  • RANK 23% Cleaner than states
  • O3 52.1% Main pollutant share

Good-day share peers

Indiana71.8%Colorado71.7%South Carolina (this)71.3%Arkansas71.2%
Good-day share neighbourhood · nearest ABS peers vs South Carolina

South Carolina's 71.3% Good-day share is cleaner than 23% of monitored US states; Berkeley and Spartanburg County bracket the in-state range. Open Berkeley County →

According to EPA AQS annual summaries on PlainAirData, South Carolina ranks #40 of 52 by day-weighted good-day share (71.3%) and #45 by mean county median AQI (42.8). Hawaii is #1 of 52 by day-weighted good-day share (93.8% of monitored days) at mean county median-AQI #4 (27.3) ≠ Alaska #1 lowest mean county median AQI (20.3) at good-day share #8 (84.4%).

Data updated August 2026

What changed, what drives it, and how thick is the sample

Three derived views WPR-style word count does not substitute for: release-over-release movement from county annual rows, the EPA main-pollutant day mix, and how many counties sit below the 100-day ranking floor.

Release change

71.3%

Good-day share in 2025, up 2.0 percentage points vs 2024. County-mean median AQI 43, 0.6 points lower (cleaner) than 2024.

Pollutant mix

Ozone

Main driver on 52.1% of pollutant-assigned days.

  • Ozone 52.1%
  • PM2.5 47.8%

Monitoring coverage

330

Average monitored days per county in the latest release. Every monitored county clears the 100-day ranking floor.

Counties Monitored

13

Good Days %

71.3%

Avg Median AQI

43

Total Unhealthy Days

2

Best Air Quality

Berkeley County

Worst Air Quality

Spartanburg County

Where South Carolina sits nationally

COUNT-derived placement among 52 US states with at least 365 monitored days in the latest county release. South Carolina's day-weighted Good-day share is 71.3% - cleaner than 23% of that comparison set.

South Carolina Good-day share vs. every US state

Day-weighted share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release

71.3% 23rd percentile higher than 23% of 52 US states

0.0%–5.0%: 0 US states (0%). Below this entry. 5.0%–10.0%: 0 US states (0%). Below this entry. 10.0%–15.0%: 0 US states (0%). Below this entry. 15.0%–20.0%: 0 US states (0%). Below this entry. 20.0%–25.0%: 0 US states (0%). Below this entry. 25.0%–30.0%: 0 US states (0%). Below this entry. 30.0%–35.0%: 0 US states (0%). Below this entry. 35.0%–40.0%: 0 US states (0%). Below this entry. 40.0%–45.0%: 0 US states (0%). Below this entry. 45.0%–50.0%: 0 US states (0%). Below this entry. 50.0%–55.0%: 0 US states (0%). Below this entry. 55.0%–60.0%: 0 US states (0%). Below this entry. 60.0%–65.0%: 2 US states (4%). Below this entry. 65.0%–70.0%: 9 US states (17%). Below this entry. 70.0%–75.0%: 11 US states (21%). This entry sits in this band. 75.0%–80.0%: 11 US states (21%). Above this entry. 80.0%–85.0%: 13 US states (25%). Above this entry. 85.0%–90.0%: 5 US states (10%). Above this entry. 90.0%–95.0%: 1 US states (2%). Above this entry. 95.0%–100.0%: 0 US states (0%). Above this entry. 100.0%–105.0%: 0 US states (0%). Above this entry. This state 0.0% 100% every floor-qualified US state, bucketed by value

Each bar is a band; taller bars hold more US states. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025

Which counties in South Carolina have the cleanest and most polluted air?

Cleanest counties in South Carolina

Share of monitored days rated Good (AQI 0–50)

  1. 1 Berkeley County 93.3%
  2. 2 Anderson County 91.3%
  3. 3 Aiken County 90.6%
  4. 4 Darlington County 89%
  5. 5 Horry County 82.5%
  6. 6 York County 76.5%
  7. 7 Edgefield County 68%
  8. 8 Florence County 65.1%
  9. 9 Chesterfield County 64.1%
  10. 10 Charleston County 60.8%
  11. 11 Richland County 58.1%
  12. 12 Greenville County 55.6%

Good-day share · EPA Air Quality System

County Good % Median AQI
Berkeley 93.3% 35
Anderson 91.3% 40
Aiken 90.6% 39
Darlington 89.0% 40
Horry 82.5% 39
York 76.5% 43
Edgefield 68.0% 43
Florence 65.1% 44
Chesterfield 64.1% 44
Charleston 60.8% 47
Richland 58.1% 47
Greenville 55.6% 47
Spartanburg 55.1% 48

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025. See our methodology for how AQI and median figures are computed.

Coverage: 13 counties in South Carolina with active monitoring stations. Unmonitored counties are not represented.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files, aggregated to the state level · 2020–2025

Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.

Informational only, not professional advice. Data from EPA AQS. See our disclaimer.