Metro area air quality · 2025

Portsmouth, OH

Median AQI 45 (Good). 58.6% of monitored days rated Good across this metro's EPA monitoring network.

45
Median AQI
58.6%
Good-air days
1
Unhealthy days
22%
Cleaner than US metros

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

The verdict

The Portsmouth, OH metro runs good on the EPA scale, among the more polluted US metros, a median AQI of 45 with 58.6% of 273 monitored days in the Good band.

45
median AQI · Good
58.6%
days rated Good
22%
cleaner than US metros
238
worst single reading

1 day reached Unhealthy or worse across the metro's monitors in 2025.

Insights: Portsmouth, OH metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 45 over 273 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 160 Good days (59%), 111 Moderate (41%), and 1 Unhealthy-for-Sensitive-Groups (0%). The 90th-percentile AQI finished at 64 while the highest single-day reading hit 238 (Very Unhealthy). Metro residents averaged roughly 17.6 clean-air days per 30-day window across the reporting year.

Across the 2020–2025 trend window, good days shifted by -187 and the median AQI moved +31 points, which classifies the multi-year trajectory as worsening. The metro recorded 1 unhealthy-or-worse days combined, on those days the EPA recommends that sensitive groups limit prolonged outdoor exertion, and many schools and athletic programs adjust outdoor activity accordingly. Metros with comparable AQI profiles include Akron, OH (62.2% good, AQI 45); Carson City, NV (79.3% good, AQI 45); Clinton, IA (59.9% good, AQI 45).

Air Quality Summary

Median AQI

45

Good

Good Days

58.6%

160 of 273 days

Max AQI

238

Very Unhealthy

Health Grade

Moderate

90th pct: 64

AQI Day Breakdown (2025)

Distribution of 273 monitored days across EPA AQI categories.

Good

160

59%

Moderate

111

41%

USG

1

0%

Unhealthy

0

0%

Very Unhealthy

1

0%

Hazardous

0

0%

Health Impact Assessment

Moderate

The Portsmouth, OH metro area's air quality is rated Moderate based on 58.6% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.

Air quality reached unhealthy levels on 1 days in 2025 (0 Unhealthy, 1 Very Unhealthy). Sensitive groups, including people with asthma, COPD, cardiovascular conditions, children, and adults over 65, should review the daily breakdown and follow local advisories.

Sensitive group advisory

People with asthma, COPD, heart disease, children, pregnant women, and adults 65+ should follow EPA AQI alerts daily and limit outdoor exertion when AQI exceeds 100. Real-time conditions: airnow.gov.

How does the Portsmouth, OH metro compare?

How Portsmouth, OH compares

Good-day share worse than US avg
Portsmouth, OH 58.6%
Akron, OH 62.2%
US average 71.3%
Median AQI worse than US avg
Portsmouth, OH 45
Akron, OH 45
US average 41
Unhealthy days / yr about average
Portsmouth, OH 1
Akron, OH 0
US average 1

5-Year Air Quality Trend

Air quality is worsening in the Portsmouth, OH metro. Best year: 2020 (347 good days).

Year Good Moderate Unhealthy Median AQI
2020 347 19 0 14
2021 333 32 0 16
2022 340 25 0 17
2023 223 135 2 44
2024 248 118 0 40
2025 160 111 0 45

Metros with Similar Air Quality

Metro areas across the US with a similar median AQI to Portsmouth, OH.

Akron, OH

AQI 45 · 62.2% good

45

Carson City, NV

AQI 45 · 79.3% good

45

Clinton, IA

AQI 45 · 59.9% good

45

Davenport-Moline-Rock Island, IA-IL

AQI 45 · 58.4% good

45

Española, NM

AQI 45 · 79.9% good

45

Gadsden, AL

AQI 45 · 63.5% good

45

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 Portsmouth, OH metro area? ▼
The Portsmouth, OH metro area has a median Air Quality Index (AQI) of 45, rated "Good." 58.6% of monitored days (160 out of 273) had good air quality in 2025.
How many unhealthy air days does Portsmouth, OH have? ▼
In 2025, the Portsmouth, OH metro area recorded 1 unhealthy air days (0 Unhealthy, 1 Very Unhealthy, 0 Hazardous). The maximum AQI reached 238.
Is air quality in Portsmouth, OH getting better or worse? ▼
Air quality in the Portsmouth, OH metro is worsening based on 5-year trends (2020-2025). Best year: 2020 with 347 good days. Worst year: 2025 with 160 good days.
What does AQI 45 mean for health? ▼
An AQI of 45 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 Portsmouth, OH? ▼
The 90th percentile AQI for the Portsmouth, OH metro area is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 238 (Very Unhealthy).
How does Portsmouth, OH compare to other metro areas? ▼
The Portsmouth, OH metro has 58.6% good air days. Similar metros: Akron, OH (62.2% good), Carson City, NV (79.3% good), Clinton, IA (59.9% 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.