Median AQI
14
Good
South Dakota · County air quality · 2025
Hughes County, South Dakota
Median AQI 14 (Good). 94.4% of monitored days rated Good, direct from EPA Air Quality System stations.
- 14
- Median AQI
- 94.4%
- Good-air days
- 0
- Unhealthy days
- 87%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Hughes County's air is good on balance, cleaner than most US counties, a median AQI of 14 with 94.4% of 179 monitored days in the Good band, driven mainly by PM2.5.
- 14
- median AQI · Good
- 94.4%
- days rated Good
- PM2.5
- main pollutant
- 87%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 88.
Data updated July 2026
- Good · 169 d · 94.4%
- Moderate · 10 d · 5.6%
How did Hughes County's air break down in 2025?
Across 179 monitored days, 169 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 88 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 179 days monitored. Median AQI: 14 (Good).
Insights: Hughes County, South Dakota. EPA monitors recorded a median Air Quality Index of 14 across 179 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 169 (94%) fell in the Good band (AQI 0–50), 10 (6%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 41, while the worst single-day peak hit 88 (Moderate). Residents averaged about 28.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (179 days). Across the 2020–2025 trend window, good days shifted by -163 and the median AQI moved -5 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 88, moderate but never Unhealthy. Nearby counties show comparable readings: Brookings (53.0% good, AQI 48); Brown (87.1% good, AQI 25); Clay (82.6% good, AQI 37); Codington (82.1% good, AQI 33); Custer (72.4% good, AQI 46); Jackson (78.5% good, AQI 44).
Air Quality Summary
Good Days
94.4%
169 of 179 monitored days
19.4pp vs 75% target
Max AQI Recorded
88
Moderate
Health Grade
Excellent
90th-pct AQI 41
Hughes County, Good days share 94.4%
National avg
Share of monitored days at AQI 0-50 (Good band).
Hughes 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 179 monitored days across EPA AQI categories.
Good
169
94%
Moderate
10
6%
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 Hughes County.
- PM2.5 · 179 days · 100.0%
Health Impact Assessment
Excellent
Hughes County's air quality is rated Excellent based on 94.4% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 94.4% of monitored days in 2025, with a median AQI of 14. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 179 of 179 monitored days.
5-Year Air Quality Trend
Air quality is stable in Hughes County. Best year: 2022 (352 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 332 | 23 | 0 | 0 | 19 | 79 |
| 2021 | 325 | 22 | 1 | 0 | 12 | 268 |
| 2022 | 352 | 10 | 0 | 0 | 7 | 63 |
| 2023 | 321 | 30 | 3 | 4 | 14 | 223 |
| 2024 | 340 | 23 | 0 | 0 | 8 | 69 |
| 2025 | 169 | 10 | 0 | 0 | 14 | 88 |
How does Hughes County compare?
How Hughes County compares
Good-day share better than US avg
Hughes County 94.4%
Brookings County, South Dakota 53.0%
US average 76.5%
Median AQI better than US avg
Hughes County 14
Brookings County, South Dakota 48
US average 38
Unhealthy days / yr about average
Hughes County 0
Brookings County, South Dakota 1
US average 0
Other Counties in South Dakota
Air quality comparison for nearby counties in South Dakota.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Hughes County.
Apache County, Arizona
AQI 14 · 99.6% good
Dawson County, Montana
AQI 14 · 95.0% good
Gallatin County, Montana
AQI 14 · 99.1% good
Klickitat County, Washington
AQI 14 · 84.2% good
Park County, Wyoming
AQI 14 · 99.5% good
Platte County, Wyoming
AQI 14 · 87.7% good
What Hughes 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 14 means for exposure. Health guidance
- See how Hughes County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Hughes County with its South Dakota neighbours before drawing a conclusion about the region. All of South Dakota
Based on 179 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 Hughes County, South Dakota? ▼
Hughes County has a median Air Quality Index (AQI) of 14, rated "Good." 94.4% of monitored days (169 out of 179) had good air quality in 2025.
What is the main pollutant in Hughes County? ▼
The primary pollutant in Hughes County is Fine Particles (PM2.5), which was the main AQI driver on 179 days (100% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Hughes County have? ▼
In 2025, Hughes County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 88.
Is the air quality in Hughes County getting better or worse? ▼
Air quality in Hughes County is stable based on 5-year trends (2020-2025). Best year: 2022 with 352 good days. Worst year: 2025 with 169 good days.
What does AQI 14 mean for health? ▼
Hughes County's median AQI of 14 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 Hughes County compare to other counties in South Dakota? ▼
Hughes County has 94.4% good air days. Nearby counties in South Dakota: Brookings (53.0% good), Brown (87.1% good), Clay (82.6% good), Codington (82.1% good), Custer (72.4% good), Jackson (78.5% good).
What is the 90th percentile AQI in Hughes County? ▼
The 90th percentile AQI for Hughes County is 41, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 88 (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.