Median AQI
42
Good
South Carolina · County air quality · 2025
Darlington County, South Carolina
Median AQI 42 (Good). 87.3% of monitored days rated Good, direct from EPA Air Quality System stations.
- 42
- Median AQI
- 87.3%
- Good-air days
- 0
- Unhealthy days
- 70%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Darlington County's air is good on balance, cleaner than the median US county, a median AQI of 42 with 87.3% of 221 monitored days in the Good band, driven mainly by Ozone.
- 42
- median AQI · Good
- 87.3%
- days rated Good
- Ozone
- main pollutant
- 70%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 97.
Data updated July 2026
- Good · 193 d · 87.3%
- Moderate · 28 d · 12.7%
How did Darlington County's air break down in 2025?
Across 221 monitored days, 193 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 97 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 221 days monitored. Median AQI: 42 (Good).
Insights: Darlington County, South Carolina. EPA monitors recorded a median Air Quality Index of 42 across 221 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 193 (87%) fell in the Good band (AQI 0–50), 28 (13%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 51, while the worst single-day peak hit 97 (Moderate). Residents averaged about 26.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (221 days). Across the 2020–2025 trend window, good days shifted by -60 and the median AQI moved +10 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 97, moderate but never Unhealthy. Nearby counties show comparable readings: Aiken (89.1% good, AQI 39); Anderson (90.0% good, AQI 41); Berkeley (92.2% good, AQI 36); Charleston (59.0% good, AQI 47); Chesterfield (61.2% good, AQI 46); Edgefield (68.1% good, AQI 44).
Air Quality Summary
Good Days
87.3%
193 of 221 monitored days
12.3pp vs 75% target
Max AQI Recorded
97
Moderate
Health Grade
Good
90th-pct AQI 51
Darlington County, Good days share 87.3%
National avg
Share of monitored days at AQI 0-50 (Good band).
Darlington County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 221 monitored days across EPA AQI categories.
Good
193
87%
Moderate
28
13%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Darlington County.
- Ozone · 221 days · 100.0%
Health Impact Assessment
Good
Darlington County's air quality is rated Good based on 87.3% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 87.3% of monitored days in 2025, with a median AQI of 42. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 221 of 221 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Darlington County. Best year: 2021 (257 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 253 | 0 | 0 | 0 | 32 | 49 |
| 2021 | 257 | 18 | 0 | 0 | 35 | 74 |
| 2022 | 249 | 16 | 0 | 0 | 36 | 84 |
| 2023 | 238 | 33 | 0 | 0 | 40 | 93 |
| 2024 | 224 | 37 | 0 | 0 | 40 | 100 |
| 2025 | 193 | 28 | 0 | 0 | 42 | 97 |
How does Darlington County compare?
How Darlington County compares
Good-day share better than US avg
Darlington County 87.3%
Aiken County, South Carolina 89.1%
US average 76.5%
Median AQI worse than US avg
Darlington County 42
Aiken County, South Carolina 39
US average 38
Unhealthy days / yr about average
Darlington County 0
Aiken County, South Carolina 0
US average 0
Other Counties in South Carolina
Air quality comparison for nearby counties in South Carolina.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Darlington County.
Adams County, Pennsylvania
AQI 42 · 73.8% good
Anderson County, Tennessee
AQI 42 · 91.0% good
Andrew County, Missouri
AQI 42 · 84.3% good
Armstrong County, Pennsylvania
AQI 42 · 68.1% good
Baldwin County, Alabama
AQI 42 · 72.2% good
Belmont County, Ohio
AQI 42 · 63.0% good
What Darlington County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 42 means for exposure. Health guidance
- See how Darlington County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Darlington County with its South Carolina neighbours before drawing a conclusion about the region. All of South Carolina
Based on 221 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Darlington County, South Carolina? ▼
Darlington County has a median Air Quality Index (AQI) of 42, rated "Good." 87.3% of monitored days (193 out of 221) had good air quality in 2025.
What is the main pollutant in Darlington County? ▼
The primary pollutant in Darlington County is Ozone (O3), which was the main AQI driver on 221 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Darlington County have? ▼
In 2025, Darlington County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 97.
Is the air quality in Darlington County getting better or worse? ▼
Air quality in Darlington County is worsening based on 5-year trends (2020-2025). Best year: 2021 with 257 good days. Worst year: 2025 with 193 good days.
What does AQI 42 mean for health? ▼
Darlington County's median AQI of 42 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Darlington County compare to other counties in South Carolina? ▼
Darlington County has 87.3% good air days. Nearby counties in South Carolina: Aiken (89.1% good), Anderson (90.0% good), Berkeley (92.2% good), Charleston (59.0% good), Chesterfield (61.2% good), Edgefield (68.1% good).
What is the 90th percentile AQI in Darlington County? ▼
The 90th percentile AQI for Darlington County is 51, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 97 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer.
Every figure on PlainAir 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.