Median AQI
46
Good
South Carolina · County air quality · 2025
Chesterfield County, South Carolina
Median AQI 46 (Good). 61.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 46
- Median AQI
- 61.2%
- Good-air days
- 0
- Unhealthy days
- 16%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Chesterfield County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 46 with 61.2% of 273 monitored days in the Good band, driven mainly by PM2.5.
- 46
- median AQI · Good
- 61.2%
- days rated Good
- PM2.5
- main pollutant
- 16%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 103.
Data updated July 2026
- Good · 167 d · 61.2%
- Moderate · 105 d · 38.5%
- USG · 1 d · 0.4%
How did Chesterfield County's air break down in 2025?
Across 273 monitored days, 167 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 103 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 46 (Good).
Insights: Chesterfield County, South Carolina. EPA monitors recorded a median Air Quality Index of 46 across 273 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 167 (61%) fell in the Good band (AQI 0–50), 105 (38%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 59, while the worst single-day peak hit 103 (USG). Residents averaged about 18.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (190 days), Ozone (83 days). Across the 2020–2025 trend window, good days shifted by -120 and the median AQI moved +7 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 103, usg 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); Darlington (87.3% good, AQI 42); Edgefield (68.1% good, AQI 44).
Air Quality Summary
Good Days
61.2%
167 of 273 monitored days
-13.8pp vs 75% target
Max AQI Recorded
103
USG
Health Grade
Moderate
90th-pct AQI 59
Chesterfield County, Good days share 61.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Chesterfield 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 273 monitored days across EPA AQI categories.
Good
167
61%
Moderate
105
38%
USG
1
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 Chesterfield County.
- PM2.5 · 190 days · 69.6%
- Ozone · 83 days · 30.4%
Health Impact Assessment
Moderate
Chesterfield County's air quality is rated Moderate based on 61.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 61.2% of monitored days in 2025, with a median AQI of 46. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 190 of 273 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Chesterfield County. Best year: 2020 (287 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 287 | 59 | 0 | 0 | 39 | 91 |
| 2021 | 268 | 90 | 0 | 0 | 41 | 81 |
| 2022 | 273 | 70 | 0 | 0 | 40 | 97 |
| 2023 | 242 | 122 | 1 | 0 | 42 | 134 |
| 2024 | 234 | 128 | 2 | 0 | 44 | 143 |
| 2025 | 167 | 105 | 1 | 0 | 46 | 103 |
How does Chesterfield County compare?
How Chesterfield County compares
Good-day share worse than US avg
Chesterfield County 61.2%
Aiken County, South Carolina 89.1%
US average 76.5%
Median AQI worse than US avg
Chesterfield County 46
Aiken County, South Carolina 39
US average 38
Unhealthy days / yr about average
Chesterfield 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 Chesterfield County.
Bay County, Florida
AQI 46 · 60.6% good
Blount County, Tennessee
AQI 46 · 69.6% good
Cache County, Utah
AQI 46 · 61.2% good
Clark County, Indiana
AQI 46 · 59.7% good
Clark County, Ohio
AQI 46 · 59.4% good
Cochise County, Arizona
AQI 46 · 65.6% good
What Chesterfield County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 46 means for exposure. Health guidance
- See how Chesterfield County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Chesterfield County with its South Carolina neighbours before drawing a conclusion about the region. All of South Carolina
Based on 273 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 Chesterfield County, South Carolina? ▼
Chesterfield County has a median Air Quality Index (AQI) of 46, rated "Good." 61.2% of monitored days (167 out of 273) had good air quality in 2025.
What is the main pollutant in Chesterfield County? ▼
The primary pollutant in Chesterfield County is Fine Particles (PM2.5), which was the main AQI driver on 190 days (70% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Chesterfield County have? ▼
In 2025, Chesterfield County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 103.
Is the air quality in Chesterfield County getting better or worse? ▼
Air quality in Chesterfield County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 287 good days. Worst year: 2025 with 167 good days.
What does AQI 46 mean for health? ▼
Chesterfield County's median AQI of 46 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 Chesterfield County compare to other counties in South Carolina? ▼
Chesterfield County has 61.2% good air days. Nearby counties in South Carolina: Aiken (89.1% good), Anderson (90.0% good), Berkeley (92.2% good), Charleston (59.0% good), Darlington (87.3% good), Edgefield (68.1% good).
What is the 90th percentile AQI in Chesterfield County? ▼
The 90th percentile AQI for Chesterfield County is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 103 (USG).
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.