Castleton Four Corners, Vermont Air Quality
Castleton Four Corners has a median AQI of 38, earning an air quality grade of A — excellent air quality that ranks better than 70% of US cities. Air quality has remained relatively stable over the past decade. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, Castleton Four Corners recorded 142 good air quality days (79% of monitored days).
Population: 732 • County: Rutland
Current AQI
Quick Facts
| Current AQI | 10 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 38 |
| vs. U.S. Cities | Better than 70% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Castleton Four Corners is sourced from the Rutland monitoring area, located approximately 11 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Castleton Four Corners has relatively consistent air quality throughout the year without a strong seasonal peak. Air quality is primarily influenced by local traffic, industrial activity, and regional weather patterns rather than a single seasonal driver.
AQI Trend (10 Years)
Air Quality Days by Year
Castleton Four Corners Median AQI by Year
Annual EPA air quality data for Castleton Four Corners — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 38 | 142 | — | 92 | Ozone |
| 2024 | 37 | 291 | — | 86 | Ozone |
| 2023 | 38 | 267 | 2 | 147 | PM2.5 |
| 2022 | 39 | 278 | — | 74 | PM2.5 |
| 2021 | 40 | 265 | 1 | 114 | PM2.5 |
| 2020 | 39 | 283 | — | 97 | PM2.5 |
| 2019 | 40 | 281 | — | 89 | PM2.5 |
| 2018 | 39 | 264 | — | 90 | PM2.5 |
| 2017 | 40 | 268 | — | 87 | PM2.5 |
| 2016 | 38 | 290 | — | 89 | Ozone |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Castleton Four Corners Air Quality
What is the air quality in Castleton Four Corners today?
The current AQI in Castleton Four Corners is 10, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Castleton Four Corners getting better or worse?
Air quality in Castleton Four Corners has been stable. The median AQI has remained stable at around 38 over the past decade.
What is the most common air pollutant in Castleton Four Corners?
Ozone is the primary air pollutant in Castleton Four Corners, responsible for 124 days (69% of monitored days) in 2025. Ground-level ozone forms when sunlight reacts with emissions from vehicles and industry, typically peaking on hot summer afternoons.
How many unhealthy air days does Castleton Four Corners have per year?
In 2025, Castleton Four Corners recorded 79% good air quality days (142 days) out of 180 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 92.
What air quality grade does Castleton Four Corners receive?
Castleton Four Corners receives an air quality grade of A, placing it better than 70% of US cities. This is based on a median AQI of 38 in 2025, with 142 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 70% of US cities
Nearby Cities
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National Rankings
See how Castleton Four Corners compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Castleton Four Corners
Ozone is Castleton Four Corners's primary pollutant. Standard HEPA filters don't capture ozone molecules — you need activated carbon or PECO technology to chemically break them down. We highlight those units here.
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