Metro area air quality · 2025

Johnstown, PA

Median AQI 37 (Good). 77.7% of monitored days rated Good across this metro's EPA monitoring network.

37
Median AQI
77.7%
Good-air days
0
Unhealthy days
57%
Cleaner than US metros

Aggregated from EPA Air Quality System (2025), 269 monitored days. EPA AQS →

The verdict

The Johnstown, PA metro runs good on the EPA scale, cleaner than the median US metro, a median AQI of 37 with 77.7% of 269 monitored days in the Good band.

37
median AQI · Good
77.7%
days rated Good
57%
cleaner than US metros
115
worst single reading

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

Insights: Johnstown, PA metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 37 over 269 measured days in 2025, which corresponds to a Good band and a Good metro-wide health grade. The monitored-day split lands at 209 Good days (78%), 59 Moderate (22%), and 1 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 58 while the highest single-day reading hit 115 (USG). Metro residents averaged roughly 23.3 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -19 and the median AQI moved -7 points, which classifies the multi-year trajectory as improving. 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

77.7%

209 of 269 days

Max AQI

115

USG

Health Grade

Good

90th pct: 58

AQI Day Breakdown (2025)

Distribution of 269 monitored days across EPA AQI categories.

Good

209

78%

Moderate

59

22%

USG

1

0%

Unhealthy

0

0%

Very Unhealthy

0

0%

Hazardous

0

0%

Health Impact Assessment

Good

The Johnstown, PA metro area's air quality is rated Good based on 77.7% 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 Johnstown, PA metro compare?

How Johnstown, PA compares

Good-day share better than US avg
Johnstown, PA 77.7%
Athens, TN 77.5%
US average 71.3%
Median AQI better than US avg
Johnstown, PA 37
Athens, TN 37
US average 41
Unhealthy days / yr better than US avg
Johnstown, PA 0
Athens, TN 0
US average 1

5-Year Air Quality Trend

Air quality is improving in the Johnstown, PA metro. Best year: 2024 (269 good days).

Year Good Moderate Unhealthy Median AQI
2020 228 138 0 44
2021 169 183 0 51
2022 171 191 0 52
2023 213 147 2 46
2024 269 96 0 42
2025 209 59 0 37

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Johnstown, 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 Johnstown, PA metro area? ▼
The Johnstown, PA metro area has a median Air Quality Index (AQI) of 37, rated "Good." 77.7% of monitored days (209 out of 269) had good air quality in 2025.
How many unhealthy air days does Johnstown, PA have? ▼
In 2025, the Johnstown, PA metro area recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 115.
Is air quality in Johnstown, PA getting better or worse? ▼
Air quality in the Johnstown, PA metro is improving based on 5-year trends (2020-2025). Best year: 2024 with 269 good days. Worst year: 2021 with 169 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 Johnstown, PA? ▼
The 90th percentile AQI for the Johnstown, PA 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 Johnstown, PA compare to other metro areas? ▼
The Johnstown, PA metro has 77.7% 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.