Median AQI
40
Good
North Carolina · County air quality · 2025
Granville County, North Carolina
Median AQI 40 (Good). 91.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 40
- Median AQI
- 91.5%
- Good-air days
- 0
- Unhealthy days
- 79%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Granville County's air is good on balance, cleaner than most US counties, a median AQI of 40 with 91.5% of 177 monitored days in the Good band, driven mainly by Ozone.
- 40
- median AQI · Good
- 91.5%
- days rated Good
- Ozone
- main pollutant
- 79%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 87.
Data updated July 2026
- Good · 162 d · 91.5%
- Moderate · 15 d · 8.5%
How did Granville County's air break down in 2025?
Across 177 monitored days, 162 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). 177 days monitored. Median AQI: 40 (Good).
Insights: Granville County, North Carolina. EPA monitors recorded a median Air Quality Index of 40 across 177 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 162 (92%) fell in the Good band (AQI 0–50), 15 (8%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 50, while the worst single-day peak hit 87 (Moderate). Residents averaged about 27.5 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (177 days). Across the 2020–2025 trend window, good days shifted by -75 and the median AQI moved +4 points, placing the multi-year trajectory at worsening. 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
91.5%
162 of 177 monitored days
16.5pp vs 75% target
Max AQI Recorded
87
Moderate
Health Grade
Excellent
90th-pct AQI 50
Granville County, Good days share 91.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Granville 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 177 monitored days across EPA AQI categories.
Good
162
92%
Moderate
15
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 Granville County.
- Ozone · 177 days · 100.0%
Health Impact Assessment
Excellent
Granville County's air quality is rated Excellent based on 91.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 91.5% of monitored days in 2025, with a median AQI of 40. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 177 of 177 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Granville County. Best year: 2021 (237 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 237 | 1 | 0 | 0 | 36 | 51 |
| 2021 | 237 | 5 | 0 | 0 | 38 | 67 |
| 2022 | 223 | 20 | 1 | 0 | 42 | 112 |
| 2023 | 202 | 39 | 1 | 0 | 43 | 105 |
| 2024 | 206 | 37 | 1 | 0 | 42 | 101 |
| 2025 | 162 | 15 | 0 | 0 | 40 | 87 |
How does Granville County compare?
How Granville County compares
Good-day share better than US avg
Granville County 91.5%
Alexander County, North Carolina 92.4%
US average 76.5%
Median AQI worse than US avg
Granville County 40
Alexander County, North Carolina 39
US average 38
Unhealthy days / yr about average
Granville 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 Granville County.
Amador County, California
AQI 40 · 84.8% good
Anne Arundel County, Maryland
AQI 40 · 87.2% good
Arlington County, Virginia
AQI 40 · 84.8% good
Bergen County, New Jersey
AQI 40 · 71.1% good
Berkeley County, West Virginia
AQI 40 · 81.1% good
Billings County, North Dakota
AQI 40 · 80.3% good
What Granville 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 40 means for exposure. Health guidance
- See how Granville County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Granville County with its North Carolina neighbours before drawing a conclusion about the region. All of North Carolina
Based on 177 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 Granville County, North Carolina? ▼
Granville County has a median Air Quality Index (AQI) of 40, rated "Good." 91.5% of monitored days (162 out of 177) had good air quality in 2025.
What is the main pollutant in Granville County? ▼
The primary pollutant in Granville County is Ozone (O3), which was the main AQI driver on 177 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Granville County have? ▼
In 2025, Granville County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 87.
Is the air quality in Granville County getting better or worse? ▼
Air quality in Granville County is worsening based on 5-year trends (2020-2025). Best year: 2021 with 237 good days. Worst year: 2025 with 162 good days.
What does AQI 40 mean for health? ▼
Granville County's median AQI of 40 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 Granville County compare to other counties in North Carolina? ▼
Granville County has 91.5% 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 Granville County? ▼
The 90th percentile AQI for Granville County is 50, 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.