Metro area air quality · 2025

St. Marys, PA

Median AQI 36 (Good). 95.3% of monitored days rated Good across this metro's EPA monitoring network.

Compiled by PlainAirData · August 23, 2026

36
Median AQI: 95.3%
Good-air days: 0
Unhealthy days: 95%
Cleaner than US metros

St. Marys, PA posted a 2025 median AQI of 36 (Good) with 95.3% Good days

According to the U.S. EPA Air Quality System, the St. Marys, PA CBSA recorded a median AQI of 36 across 361 monitored days in 2025, with 95.3% 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 St. Marys, PA CBSA's 95.3% Good-day share places it cleaner than 95% of US metros in 2025.
Closest median-AQI peer: Atlantic City-Hammonton, NJ (82.2% Good, median AQI 36) is the closest nationwide median-AQI peer to St. Marys, PA.
2020–2025 Good-day shift: St. Marys, PA's Good-day share moved -4.2 points from 2020 to 2025 (median AQI +2).
Median AQI: Median AQI: 36

Aggregated from EPA Air Quality System (2025), 361 monitored days. EPA AQS →

The verdict

The St. Marys, PA metro runs good on the EPA scale, among the cleanest 10% of US metros, a median AQI of 36 with 95.3% of 361 monitored days in the Good band.

36
median AQI · Good: 95.3%
days rated Good: 95%
cleaner than US metros: 84
worst single reading

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

St. Marys, PA metro's peak single-day AQI rose from 67 to 84 between the 2024 and 2025 EPA annual releases, a change of +17 points.

Insights: St. Marys, PA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 36 over 361 measured days in 2025, which corresponds to a Good band and a Excellent metro-wide health grade. The monitored-day split lands at 344 Good days (95%), 17 Moderate (5%), and 0 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 47 while the highest single-day reading hit 84 (Moderate). Metro residents averaged roughly 28.6 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -4.2 points and the median AQI moved +2 points, which classifies the multi-year trajectory as worsening. The metro recorded no Unhealthy-tier days in this annual dataset. Metros with comparable AQI profiles include Atlantic City-Hammonton, NJ (82.2% good, AQI 36); Barnstable Town, MA (93.7% good, AQI 36); Bemidji, MN (79.1% good, AQI 36).

Air Quality Summary

Median AQI

Good

Good Days

95.3%

344 of 361 days

Max AQI

Moderate

Health Grade

Excellent

90th pct: 47

AQI Day Breakdown (2025)

Distribution of 361 monitored days across EPA AQI categories.

Good

344

95%

Moderate

USG

Unhealthy

Very Unhealthy

Hazardous

Health Impact Assessment

Excellent

The St. Marys, PA metro area's air quality is rated Excellent based on 95.3% 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 St. Marys, PA metro compare?

How St. Marys, PA compares

Compare against

Good-day share better than typical

St. Marys, PA 95.3%

Atlantic City-Hammonton, NJ 82.2%

Typical US metro 70.6%

Median AQI better than typical

St. Marys, PA 36

Atlantic City-Hammonton, NJ 36

Typical US metro 41

Unhealthy days / yr better than typical

St. Marys, PA 0

Atlantic City-Hammonton, NJ 0

Typical US metro 1

5-Year Air Quality Trend

Air quality is worsening in the St. Marys, PA metro. Highest Good-day share: 2020 (99.4%, 356 of 358 monitored days).

Year	Good	Moderate	Median AQI	Max AQI
2020	356	2	34	67
2021	340	18	34	87
2022	353	9	35	101
2023	343	20	35	100
2024	343	15	34	67
2025	344	17	36	84

Metros with a similar median AQI

CBSA peers nationwide whose annual median AQI sits near St. Marys, PA (36).

Atlantic City-Hammonton, NJ

Median AQI 36 · 82.2% Good-day share

Barnstable Town, MA

Median AQI 36 · 93.7% Good-day share

Bemidji, MN

Median AQI 36 · 79.1% Good-day share

Claremont-Lebanon, NH-VT

Median AQI 36 · 83.6% Good-day share

Crestview-Fort Walton Beach-Destin, FL

Median AQI 36 · 93.9% Good-day share

East Stroudsburg, PA

Median AQI 36 · 88.3% Good-day share

Metros with similar unhealthy-day exposure

A second relationship type: metros whose unhealthy-or-worse day count is closest to St. Marys, PA'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

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 St. Marys, PA metro area? ▼

The St. Marys, PA metro area has a median Air Quality Index (AQI) of 36, rated "Good." 95.3% of monitored days (344 out of 361) had good air quality in 2025.

How many unhealthy air days does St. Marys, PA have? ▼

In 2025, the St. Marys, PA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 84.

Is air quality in St. Marys, PA getting better or worse? ▼

Air quality in the St. Marys, PA metro is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 99.4% (356 of 358 days). Lowest qualifying Good-day share: 2023 at 94.5% (343 of 363 days).

What does AQI 36 mean for health? ▼

An AQI of 36 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 St. Marys, PA? ▼

The 90th percentile AQI for the St. Marys, PA metro area is 47, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 84 (Moderate).

How does St. Marys, PA compare to other metro areas? ▼

The St. Marys, PA metro has 95.3% good air days. Similar metros: Atlantic City-Hammonton, NJ (82.2% good), Barnstable Town, MA (93.7% good), Bemidji, MN (79.1% 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 Accessed 2026-07-06

Send the source-year summary or download its ready-to-use data card.

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Every figure on PlainAirData 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.