Metro area air quality · 2025
Portsmouth, OH
Median AQI 46 (Good). 55.9% of monitored days rated Good across this metro's EPA monitoring network.
- 46
- Median AQI
- 55.9%
- Good-air days
- 1
- Unhealthy days
- 18%
- Cleaner than US metros
Portsmouth, OH posted a 2025 median AQI of 46 (Good) with 55.9% Good days
According to the U.S. EPA Air Quality System, the Portsmouth, OH CBSA recorded a median AQI of 46 across 365 monitored days in 2025, with 55.9% rated Good and 1 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 Portsmouth, OH CBSA's 55.9% Good-day share places it cleaner than 18% of US metros in 2025.
- Closest median-AQI peer
- Albany, GA (57.3% Good, median AQI 46) is the closest nationwide median-AQI peer to Portsmouth, OH.
- 2020–2025 Good-day shift
- Portsmouth, OH's Good-day share moved -38.6 points from 2020 to 2025 (median AQI +32).
- Median AQI
- Median AQI: 46
Aggregated from EPA Air Quality System (2025), 365 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 46 with 55.9% of 365 monitored days in the Good band.
- 46
- median AQI · Good
- 55.9%
- days rated Good
- 18%
- cleaner than US metros
- 238
- worst single reading
1 day reached Unhealthy or worse across the metro's monitors in 2025.
Annual release change
What changed in the 2025 EPA annual release
- Portsmouth, OH metro's peak single-day AQI rose from 80 to 238 between the 2024 and 2025 EPA annual releases, a change of +158 points.
- Portsmouth, OH metro's Good-day share fell from 67.8% to 56.2% between the 2024 and 2025 EPA annual releases, a change of -11.6 percentage points.
- Portsmouth, OH metro's median AQI rose from 40 to 46 between the 2024 and 2025 EPA annual releases, a change of +6 points.
Insights: Portsmouth, OH metro. Aggregated EPA AQS monitors across this Core-Based Statistical Area logged a median Air Quality Index of 46 over 365 measured days in 2025, which corresponds to a Good band and a Moderate metro-wide health grade. The monitored-day split lands at 204 Good days (56%), 159 Moderate (44%), 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 16.8 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 -38.6 points and the median AQI moved +32 points, which classifies the multi-year trajectory as worsening. The annual record contains 1 day at Unhealthy or worse. On that day, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Metros with comparable AQI profiles include Albany, GA (57.3% good, AQI 46); Athens-Clarke County, GA (57.8% good, AQI 46); Brookings, SD (58.6% good, AQI 46).
Air Quality Summary
Median AQI
46
Good
Good Days
55.9%
204 of 365 days
Max AQI
238
Very Unhealthy
Health Grade
Moderate
90th pct: 64
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
204
56%
Moderate
159
44%
USG
1
0%
Unhealthy
0
0%
Very Unhealthy
1
0%
Hazardous
0
0%
Health Impact Assessment
The Portsmouth, OH metro area's air quality is rated Moderate based on 55.9% 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
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 | Max AQI |
|---|---|---|---|---|---|
| 2020 | 347 | 19 | 0 | 14 | 93 |
| 2021 | 333 | 32 | 0 | 16 | 86 |
| 2022 | 340 | 25 | 0 | 17 | 74 |
| 2023 | 223 | 135 | 2 | 44 | 172 |
| 2024 | 248 | 118 | 0 | 40 | 80 |
| 2025 | 204 | 159 | 0 | 46 | 238 |
Metros with a similar median AQI
CBSA peers nationwide whose annual median AQI sits near Portsmouth, OH (46).
Albany, GA
Median AQI 46 · 57.3% Good-day share
Athens-Clarke County, GA
Median AQI 46 · 57.8% Good-day share
Brookings, SD
Median AQI 46 · 58.6% Good-day share
Chico, CA
Median AQI 46 · 65.2% Good-day share
Colorado Springs, CO
Median AQI 46 · 68.2% Good-day share
Davenport-Moline-Rock Island, IA-IL
Median AQI 46 · 56.7% Good-day share
Metros with similar unhealthy-day exposure
A second relationship type: metros whose unhealthy-or-worse day count is closest to Portsmouth, OH's 1 (independent of median AQI).
Ann Arbor, MI
1 unhealthy-or-worse days · median AQI 41
Bangor, ME
1 unhealthy-or-worse days · median AQI 33
Baraboo, WI
1 unhealthy-or-worse days · median AQI 35
Bartlesville, OK
1 unhealthy-or-worse days · median AQI 44
Beaumont-Port Arthur, TX
1 unhealthy-or-worse days · median AQI 52
Beaver Dam, WI
1 unhealthy-or-worse days · median AQI 40
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? ▼
How many unhealthy air days does Portsmouth, OH have? ▼
Is air quality in Portsmouth, OH getting better or worse? ▼
What does AQI 46 mean for health? ▼
What is the 90th percentile AQI for Portsmouth, OH? ▼
How does Portsmouth, OH compare to other metro areas? ▼
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
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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.