Metro area air quality · 2025

Somerset, PA

Median AQI 37 (Good). 94.2% of monitored days rated Good across this metro's EPA monitoring network.

37
Median AQI
94.2%
Good-air days
0
Unhealthy days
91%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 243 monitored days. EPA AQS →

The verdict

The Somerset, PA metro runs good on the EPA scale, among the cleanest 10% of US metros, a median AQI of 37 with 94.2% of 243 monitored days in the Good band.

37
median AQI · Good
94.2%
days rated Good
91%
cleaner than US metros
93
worst single reading

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

Insights: Somerset, PA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 37 over 243 measured days in 2025, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 229 Good days (94%), 14 Moderate (6%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 46 while the highest single-day reading hit 93 (Moderate). Metro residents averaged roughly 28.3 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -128 and the median AQI moved +3 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 Athens, TN (77.5% good, AQI 37); Bemidji, MN (88.8% good, AQI 37); Chambersburg-Waynesboro, PA (93.0% good, AQI 37).

Air Quality Summary

Median AQI

37

Good

Good Days

94.2%

229 of 243 days

Max AQI

93

Moderate

Health Grade

Excellent

90th pct: 46

AQI Day Breakdown (2025)

Distribution of 243 monitored days across EPA AQI categories.

Good

229

94%

Moderate

14

6%

USG

0

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Excellent

The Somerset, PA metro area's air quality is rated Excellent based on 94.2% 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 Somerset, PA metro compare?

How Somerset, PA compares

Good-day share better than US avg
Somerset, PA 94.2%
Athens, TN 77.5%
US average 71.3%
Median AQI better than US avg
Somerset, PA 37
Athens, TN 37
US average 41
Unhealthy days / yr better than US avg
Somerset, PA 0
Athens, TN 0
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Somerset, PA metro. Best year: 2020 (357 good days).

Year Good Moderate Unhealthy Median AQI
2020 357 8 0 34
2021 339 24 0 34
2022 351 9 0 34
2023 333 32 0 35
2024 323 35 0 37
2025 229 14 0 37

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Somerset, PA.

Athens, TN

AQI 37 · 77.5% good

37

Bemidji, MN

AQI 37 · 88.8% good

37

Chambersburg-Waynesboro, PA

AQI 37 · 93.0% good

37

Crestview-Fort Walton Beach-Destin, FL

AQI 37 · 92.7% good

37

Gainesville, FL

AQI 37 · 90.1% good

37

Grand Island, NE

AQI 37 · 80.2% good

37

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 Somerset, PA metro area? ▼
The Somerset, PA metro area has a median Air Quality Index (AQI) of 37, rated "Good." 94.2% of monitored days (229 out of 243) had good air quality in 2025.
How many unhealthy air days does Somerset, PA have? ▼
In 2025, the Somerset, PA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 93.
Is air quality in Somerset, PA getting better or worse? ▼
Air quality in the Somerset, PA metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 357 good days. Worst year: 2025 with 229 good days.
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.
What is the 90th percentile AQI for Somerset, PA? ▼
The 90th percentile AQI for the Somerset, PA metro area is 46, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 93 (Moderate).
How does Somerset, PA compare to other metro areas? ▼
The Somerset, PA metro has 94.2% good air days. Similar metros: Athens, TN (77.5% good), Bemidji, MN (88.8% good), Chambersburg-Waynesboro, PA (93.0% 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.