Median AQI
39
Good
North Carolina · County air quality · 2025
Alexander County, North Carolina
Median AQI 39 (Good). 92.4% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 92.4%
- Good-air days
- 0
- Unhealthy days
- 81%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Alexander County's air is good on balance, cleaner than most US counties, a median AQI of 39 with 92.4% of 184 monitored days in the Good band, driven mainly by Ozone.
- 39
- median AQI · Good
- 92.4%
- days rated Good
- Ozone
- main pollutant
- 81%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 80.
Data updated July 2026
- Good · 170 d · 92.4%
- Moderate · 14 d · 7.6%
How did Alexander County's air break down in 2025?
Across 184 monitored days, 170 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 80 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 184 days monitored. Median AQI: 39 (Good).
Insights: Alexander County, North Carolina. EPA monitors recorded a median Air Quality Index of 39 across 184 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 170 (92%) fell in the Good band (AQI 0–50), 14 (8%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 49, while the worst single-day peak hit 80 (Moderate). Residents averaged about 27.7 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (184 days). Across the 2020–2025 trend window, good days shifted by -127 and the median AQI moved +6 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 80, moderate but never Unhealthy. Nearby counties show comparable readings: 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); Catawba (67.2% good, AQI 43).
Air Quality Summary
Good Days
92.4%
170 of 184 monitored days
17.4pp vs 75% target
Max AQI Recorded
80
Moderate
Health Grade
Excellent
90th-pct AQI 49
Alexander County, Good days share 92.4%
National avg
Share of monitored days at AQI 0-50 (Good band).
Alexander 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 184 monitored days across EPA AQI categories.
Good
170
92%
Moderate
14
8%
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 Alexander County.
- Ozone · 184 days · 100.0%
Health Impact Assessment
Excellent
Alexander County's air quality is rated Excellent based on 92.4% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 92.4% of monitored days in 2025, with a median AQI of 39. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 184 of 184 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Alexander County. Best year: 2020 (297 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 297 | 3 | 0 | 0 | 33 | 54 |
| 2021 | 212 | 33 | 0 | 0 | 41 | 80 |
| 2022 | 280 | 20 | 0 | 0 | 37 | 90 |
| 2023 | 275 | 26 | 1 | 0 | 38 | 105 |
| 2024 | 213 | 32 | 0 | 0 | 41 | 93 |
| 2025 | 170 | 14 | 0 | 0 | 39 | 80 |
How does Alexander County compare?
How Alexander County compares
Good-day share better than US avg
Alexander County 92.4%
Avery County, North Carolina 93.9%
US average 76.5%
Median AQI worse than US avg
Alexander County 39
Avery County, North Carolina 38
US average 38
Unhealthy days / yr about average
Alexander County 0
Avery 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 Alexander County.
Ada County, Idaho
AQI 39 · 80.6% good
Aiken County, South Carolina
AQI 39 · 89.1% good
Albany County, New York
AQI 39 · 67.4% good
Ashland County, Wisconsin
AQI 39 · 85.6% good
Bennington County, Vermont
AQI 39 · 82.9% good
Boyd County, Kentucky
AQI 39 · 82.8% good
What Alexander 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 39 means for exposure. Health guidance
- See how Alexander County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Alexander County with its North Carolina neighbours before drawing a conclusion about the region. All of North Carolina
Based on 184 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 Alexander County, North Carolina? ▼
Alexander County has a median Air Quality Index (AQI) of 39, rated "Good." 92.4% of monitored days (170 out of 184) had good air quality in 2025.
What is the main pollutant in Alexander County? ▼
The primary pollutant in Alexander County is Ozone (O3), which was the main AQI driver on 184 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Alexander County have? ▼
In 2025, Alexander County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 80.
Is the air quality in Alexander County getting better or worse? ▼
Air quality in Alexander County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 297 good days. Worst year: 2025 with 170 good days.
What does AQI 39 mean for health? ▼
Alexander County's median AQI of 39 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 Alexander County compare to other counties in North Carolina? ▼
Alexander County has 92.4% good air days. Nearby counties in North Carolina: Avery (93.9% good), Buncombe (71.4% good), Caldwell (96.2% good), Carteret (94.2% good), Caswell (94.6% good), Catawba (67.2% good).
What is the 90th percentile AQI in Alexander County? ▼
The 90th percentile AQI for Alexander County is 49, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 80 (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.