Metro area air quality · 2025

Keene, NH

Median AQI 37 (Good). 78.9% of monitored days rated Good across this metro's EPA monitoring network.

Compiled by PlainAirData · August 23, 2026

37
Median AQI: 78.9%
Good-air days: 0
Unhealthy days: 65%
Cleaner than US metros

Keene, NH posted a 2025 median AQI of 37 (Good) with 78.9% Good days

According to the U.S. EPA Air Quality System, the Keene, NH CBSA recorded a median AQI of 37 across 365 monitored days in 2025, with 78.9% rated Good and 0 unhealthy or worse. This is an annual metro comparison, not a live advisory.

Data source EPA Air Quality System (AQS)

Cleaner than US metros: The Keene, NH CBSA's 78.9% Good-day share places it cleaner than 65% of US metros in 2025.
Closest median-AQI peer: Alexandria, LA (73.7% Good, median AQI 37) is the closest nationwide median-AQI peer to Keene, NH.
2020–2025 Good-day shift: Keene, NH's Good-day share moved -2.4 points from 2020 to 2025 (median AQI +0).
Median AQI: Median AQI: 37

Aggregated from EPA Air Quality System (2025), 365 monitored days. EPA AQS →

The verdict

Keene, NH's median AQI 37 is in the lower (cleaner) CBSA tercile on this site. On the EPA scale the metro runs good, cleaner than the median US metro, with a median AQI of 37 and 78.9% of 365 monitored days in the Good band.

37
median AQI · Good: 78.9%
days rated Good: 65%
cleaner than US metros: 115
worst single reading

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

Keene, NH metro's Good-day share fell from 82.5% to 79.3% between the 2024 and 2025 EPA annual releases, a change of -3.2 percentage points.
Keene, NH metro's peak single-day AQI rose from 93 to 115 between the 2024 and 2025 EPA annual releases, a change of +22 points.

Keene, NH's median AQI 37 is in the lower (cleaner) CBSA tercile on this site. Signature read: median AQI 37 (low tercile vs CBSA corpus). Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 37 over 365 measured days in 2025 (Good / Good). The monitored-day split lands at 288 Good (79%), 75 Moderate (21%), and 2 Unhealthy-for-Sensitive-Groups (1%). The 90th-percentile AQI finished at 57; the highest single-day reading hit 115 (USG).

Across 2020–2025, Good-day share shifted -2.4 points and median AQI moved +0 (stable). No Unhealthy-tier days appear in this annual dataset. Metros with comparable AQI profiles include Alexandria, LA (73.7% good, AQI 37); Athens, TN (78.2% good, AQI 37); Bennington, VT (83.6% good, AQI 37).

Understanding AQI →

Air Quality Summary

Median AQI

Good

Good Days

78.9%

288 of 365 days

Max AQI

115

USG

Health Grade

Good

90th pct: 57

AQI Day Breakdown (2025)

Distribution of 365 monitored days across EPA AQI categories.

Good

288

79%

Moderate

21%

USG

Unhealthy

Very Unhealthy

Hazardous

Health Impact Assessment

Good

The Keene, NH metro area's air quality is rated Good based on 78.9% 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

Compare against

Good-day share better than typical

Keene, NH 78.9%

Alexandria, LA 73.7%

Typical US metro 70.6%

Median AQI better than typical

Keene, NH 37

Alexandria, LA 37

Typical US metro 41

Unhealthy days / yr better than typical

Keene, NH 0

Alexandria, LA 0

Typical US metro 1

5-Year Air Quality Trend

Air quality is stable in the Keene, NH metro. Highest Good-day share: 2022 (83.3%, 304 of 365 monitored days).

Year	Good	Moderate	Median AQI	Max AQI
2020	299	67	37	78
2021	263	100	40	127
2022	304	61	37	84
2023	253	108	41	125
2024	302	64	36	93
2025	288	75	37	115

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near Keene, NH (37).

Alexandria, LA

Median AQI 37 · 73.7% Good-day share

Athens, TN

Median AQI 37 · 78.2% Good-day share

Bennington, VT

Median AQI 37 · 83.6% Good-day share

Blacksburg-Christiansburg-Radford, VA

Median AQI 37 · 94.4% Good-day share

Cadillac, MI

Median AQI 37 · 86.0% Good-day share

Chambersburg-Waynesboro, PA

Median AQI 37 · 91.5% Good-day share

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to Keene, NH's 0 (independent of median AQI).

Aberdeen, SD

0 unhealthy-or-worse days · median AQI 27

Aberdeen, WA

0 unhealthy-or-worse days · median AQI 22

Adrian, MI

0 unhealthy-or-worse days · median AQI 41

Akron, OH

0 unhealthy-or-worse days · median AQI 45

Albany, GA

0 unhealthy-or-worse days · median AQI 46

Albany, OR

0 unhealthy-or-worse days · median AQI 27

Frequently Asked Questions

What does AQI 37 mean for health? ▼

An AQI of 37 is "Good", air quality is satisfactory and poses little or no health risk. This is the best category on the EPA's AQI scale.

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.

What is the air quality in the Keene, NH metro area? ▼

The Keene, NH metro area has a median Air Quality Index (AQI) of 37, rated "Good." 78.9% of monitored days (288 out of 365) had good air quality in 2025.

Is air quality in Keene, NH getting better or worse? ▼

Air quality in the Keene, NH metro is stable across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2022 at 83.3% (304 of 365 days). Lowest qualifying Good-day share: 2023 at 70.1% (253 of 361 days).

How does Keene, NH compare to other metro areas? ▼

The Keene, NH metro has 78.9% good air days. Similar metros: Alexandria, LA (73.7% good), Athens, TN (78.2% good), Bennington, VT (83.6% good).

What is the 90th percentile AQI for Keene, NH? ▼

The 90th percentile AQI for the Keene, NH metro area is 57, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 115 (USG).

Data Sources

Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by CBSA dataset for Keene, NH, 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, Keene, NH · 2020–2025 Accessed 2026-07-06