Metro area air quality · 2025

Keene, NH

Median AQI 38 (Good). 76.9% of monitored days rated Good across this metro's EPA monitoring network.

38
Median AQI
76.9%
Good-air days
0
Unhealthy days
56%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 273 monitored days. EPA AQS →

The verdict

The Keene, NH metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 38 with 76.9% of 273 monitored days in the Good band.

38
median AQI · Good
76.9%
days rated Good
56%
cleaner than US metros
115
worst single reading

No day crossed into the Unhealthy tier across the metro's monitors in 2025.

Insights: Keene, NH metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 38 over 273 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 210 Good days (77%), 61 Moderate (22%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 58 while the highest single-day reading hit 115 (USG). Metro residents averaged roughly 23.1 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -89 and the median AQI moved +1 points, which classifies the multi-year trajectory as worsening. The metro avoided any Unhealthy-tier days entirely, an outcome that typically reflects favorable wind patterns, lower industrial density, or effective regional emission controls. Metros with comparable AQI profiles include Appleton, WI (78.5% good, AQI 38); Atlantic City-Hammonton, NJ (79.6% good, AQI 38); Barnstable Town, MA (92.5% good, AQI 38).

Air Quality Summary

Median AQI

38

Good

Good Days

76.9%

210 of 273 days

Max AQI

115

USG

Health Grade

Good

90th pct: 58

AQI Day Breakdown (2025)

Distribution of 273 monitored days across EPA AQI categories.

Good

210

77%

Moderate

61

22%

USG

2

1%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Keene, NH metro area's air quality is rated Good based on 76.9% good air days. No unhealthy air days were recorded in 2025.

Air quality is generally acceptable. Unusually sensitive people should monitor real-time conditions at AirNow.gov during high-pollution events.

How does the Keene, NH metro compare?

How Keene, NH compares

Good-day share better than US avg
Keene, NH 76.9%
Appleton, WI 78.5%
US average 71.3%
Median AQI better than US avg
Keene, NH 38
Appleton, WI 38
US average 41
Unhealthy days / yr better than US avg
Keene, NH 0
Appleton, WI 1
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Keene, NH metro. Best year: 2022 (304 good days).

Year Good Moderate Unhealthy Median AQI
2020 299 67 0 37
2021 263 100 0 40
2022 304 61 0 37
2023 253 108 0 41
2024 302 64 0 36
2025 210 61 0 38

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Keene, NH.

Appleton, WI

AQI 38 · 78.5% good

38

Atlantic City-Hammonton, NJ

AQI 38 · 79.6% good

38

Barnstable Town, MA

AQI 38 · 92.5% good

38

Bay City, MI

AQI 38 · 71.8% good

38

Cadillac, MI

AQI 38 · 89.5% good

38

Claremont-Lebanon, NH-VT

AQI 38 · 81.3% good

38

More Air Quality Data

Explore EPA air quality rankings and guides across U.S. metros and counties.

Cleanest Metro Areas

U.S. metros ranked by their share of Good air-quality days.

Worst Air Quality

Counties and metros with the most unhealthy air days.

All Metro Areas

Annual AQI by CBSA for every monitored U.S. metro area.

Best and Worst City Air

What drives urban air quality and how metro areas compare.

Air Quality Guides

Frequently Asked Questions

What is the air quality in the Keene, NH metro area? ▼
The Keene, NH metro area has a median Air Quality Index (AQI) of 38, rated "Good." 76.9% of monitored days (210 out of 273) had good air quality in 2025.
How many unhealthy air days does Keene, NH have? ▼
In 2025, the Keene, NH metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 115.
Is air quality in Keene, NH getting better or worse? ▼
Air quality in the Keene, NH metro is worsening based on 5-year trends (2020-2025). Best year: 2022 with 304 good days. Worst year: 2025 with 210 good days.
What does AQI 38 mean for health? ▼
An AQI of 38 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.
What is the 90th percentile AQI for Keene, NH? ▼
The 90th percentile AQI for the Keene, NH metro area is 58, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 115 (USG).
How does Keene, NH compare to other metro areas? ▼
The Keene, NH metro has 76.9% good air days. Similar metros: Appleton, WI (78.5% good), Atlantic City-Hammonton, NJ (79.6% good), Barnstable Town, MA (92.5% good).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset, 2020–2025. See our methodology for how AQI, median, and coverage figures are computed.

Read our methodology , how this data is sourced, computed, and verified.

Source: U.S. EPA Air Quality System (AQS) Annual AQI by CBSA summary files (metro-level) · 2020–2025

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.