Median AQI
38
Good
North Carolina · County air quality · 2025
Swain County, North Carolina
Median AQI 38 (Good). 83.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 38
- Median AQI
- 83.2%
- Good-air days
- 0
- Unhealthy days
- 60%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Swain County's air is good on balance, cleaner than the median US county, a median AQI of 38 with 83.2% of 273 monitored days in the Good band, driven mainly by PM2.5.
- 38
- median AQI · Good
- 83.2%
- days rated Good
- PM2.5
- main pollutant
- 60%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 87.
Data updated July 2026
- Good · 227 d · 83.2%
- Moderate · 46 d · 16.8%
How did Swain County's air break down in 2025?
Across 273 monitored days, 227 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 87 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 38 (Good).
Insights: Swain County, North Carolina. EPA monitors recorded a median Air Quality Index of 38 across 273 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 227 (83%) fell in the Good band (AQI 0–50), 46 (17%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 53, while the worst single-day peak hit 87 (Moderate). Residents averaged about 24.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (178 days), Ozone (95 days). Across the 2020–2025 trend window, good days shifted by -74 and the median AQI moved +0 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 87, moderate but never Unhealthy. Nearby counties show comparable readings: Alexander (92.4% good, AQI 39); Avery (93.9% good, AQI 38); Buncombe (71.4% good, AQI 42); Caldwell (96.2% good, AQI 37); Carteret (94.2% good, AQI 37); Caswell (94.6% good, AQI 39).
Air Quality Summary
Good Days
83.2%
227 of 273 monitored days
8.2pp vs 75% target
Max AQI Recorded
87
Moderate
Health Grade
Good
90th-pct AQI 53
Swain County, Good days share 83.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Swain 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
227
83%
Moderate
46
17%
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 Swain County.
- PM2.5 · 178 days · 65.2%
- Ozone · 95 days · 34.8%
Health Impact Assessment
Good
Swain County's air quality is rated Good based on 83.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 83.2% of monitored days in 2025, with a median AQI of 38. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 178 of 273 monitored days.
5-Year Air Quality Trend
Air quality is stable in Swain County. Best year: 2024 (305 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 301 | 60 | 1 | 0 | 38 | 119 |
| 2021 | 261 | 92 | 1 | 0 | 40 | 147 |
| 2022 | 275 | 90 | 0 | 0 | 43 | 89 |
| 2023 | 267 | 96 | 2 | 0 | 41 | 115 |
| 2024 | 305 | 61 | 0 | 0 | 38 | 83 |
| 2025 | 227 | 46 | 0 | 0 | 38 | 87 |
How does Swain County compare?
How Swain County compares
Good-day share better than US avg
Swain County 83.2%
Alexander County, North Carolina 92.4%
US average 76.5%
Median AQI about average
Swain County 38
Alexander County, North Carolina 39
US average 38
Unhealthy days / yr about average
Swain County 0
Alexander County, North Carolina 0
US average 0
Other Counties in North Carolina
Air quality comparison for nearby counties in North Carolina.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Swain County.
Adams County, Illinois
AQI 38 · 94.4% good
Anoka County, Minnesota
AQI 38 · 82.1% good
Atlantic County, New Jersey
AQI 38 · 79.6% good
Avery County, North Carolina
AQI 38 · 93.9% good
Barnstable County, Massachusetts
AQI 38 · 92.5% good
Bay County, Michigan
AQI 38 · 71.8% good
What Swain 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 38 means for exposure. Health guidance
- See how Swain County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Swain County with its North Carolina neighbours before drawing a conclusion about the region. All of North 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 Swain County, North Carolina? ▼
Swain County has a median Air Quality Index (AQI) of 38, rated "Good." 83.2% of monitored days (227 out of 273) had good air quality in 2025.
What is the main pollutant in Swain County? ▼
The primary pollutant in Swain County is Fine Particles (PM2.5), which was the main AQI driver on 178 days (65% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Swain County have? ▼
In 2025, Swain County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 87.
Is the air quality in Swain County getting better or worse? ▼
Air quality in Swain County is stable based on 5-year trends (2020-2025). Best year: 2024 with 305 good days. Worst year: 2025 with 227 good days.
What does AQI 38 mean for health? ▼
Swain County's median AQI of 38 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 Swain County compare to other counties in North Carolina? ▼
Swain County has 83.2% good air days. Nearby counties in North Carolina: Alexander (92.4% good), Avery (93.9% good), Buncombe (71.4% good), Caldwell (96.2% good), Carteret (94.2% good), Caswell (94.6% good).
What is the 90th percentile AQI in Swain County? ▼
The 90th percentile AQI for Swain County is 53, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 87 (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.