Keene, New Hampshire Air Quality
Keene 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. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, Keene recorded 210 good air quality days (77% of monitored days) and 2 unhealthy days.
Population: 22,939 • County: Cheshire
Current AQI
Quick Facts
| Current AQI | 11 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 38 |
| vs. U.S. Cities | Better than 70% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 2 |
| 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 Keene is sourced from the Keene monitoring area, located approximately 2 miles from city center. This EPA-certified station continuously tracks particulate matter (PM2.5), the primary driver of air quality alerts in this area.
Keene 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
Keene Median AQI by Year
Annual EPA air quality data for Keene — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 38 | 210 | 2 | 115 | PM2.5 |
| 2024 | 36 | 302 | — | 93 | Ozone |
| 2023 | 41 | 253 | 2 | 125 | PM2.5 |
| 2022 | 37 | 304 | — | 84 | Ozone |
| 2021 | 40 | 263 | 1 | 127 | PM2.5 |
| 2020 | 37 | 299 | — | 78 | PM2.5 |
| 2019 | 35 | 331 | — | 82 | Ozone |
| 2018 | 36 | 300 | — | 86 | Ozone |
| 2017 | 37 | 298 | — | 93 | Ozone |
| 2016 | 37 | 290 | 1 | 105 | 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 Keene Air Quality
What is the air quality in Keene today?
The current AQI in Keene is 11, 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 Keene getting better or worse?
Air quality in Keene has been stable. The median AQI has risen 1 points (from 37 in 2016 to 38 in 2025).
What is the most common air pollutant in Keene?
PM2.5 is the primary air pollutant in Keene, responsible for 149 days (55% of monitored days) in 2025. Particulate matter originates from vehicle exhaust, wildfires, construction, and industrial activity.
How many unhealthy air days does Keene have per year?
In 2025, Keene recorded 77% good air quality days (210 days) out of 273 monitored days. There were 2 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 115.
What air quality grade does Keene receive?
Keene 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 210 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 Keene compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Keene
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