Median AQI
43
Good
Ohio · County air quality · 2025
Ashtabula County, Ohio
Median AQI 43 (Good). 81.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 43
- Median AQI
- 81.2%
- Good-air days
- 0
- Unhealthy days
- 59%
- Cleaner than US counties
Ashtabula County's 2025 annual median AQI is 43 (Good), with 81.2% Good days
According to the U.S. EPA Air Quality System, Ashtabula County, Ohio posted a 2025 median AQI of 43 (Good) across 245 monitored days, with 81.2% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Ashtabula County's 81.2% Good-day share places it cleaner than 59% of US counties in 2025.
- Closest median-AQI peer
- Baltimore (City) County (68.1% Good, median AQI 43) is the closest nationwide median-AQI peer to Ashtabula County.
- 2020–2025 trend
- Ashtabula County's floor-qualifying Good-day share is worsening from 2020 to 2025 (92.9% → 81.2%).
- Median AQI
- Median AQI: 43
The verdict
According to EPA Air Quality System monitoring data, Ashtabula County's air is good on balance, cleaner than the median US county, a median AQI of 43 with 81.2% of 245 monitored days in the Good band, driven mainly by Ozone.
- 43
- median AQI · Good
- 81.2%
- days rated Good
- Ozone
- main pollutant
- 59%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 122.
Annual release change
What changed in the 2025 EPA annual release
- Ashtabula County's Good-day share fell from 83.7% to 81.2% between the 2024 and 2025 EPA annual releases, a change of -2.4 percentage points.
- Ashtabula County's peak single-day AQI rose from 108 to 122 between the 2024 and 2025 EPA annual releases, a change of +14 points.
Data updated August 2026
- Good · 199 d · 81.2%
- Moderate · 43 d · 17.6%
- USG · 3 d · 1.2%
How did Ashtabula County's air break down in 2025?
Across 245 monitored days, 199 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 122 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 245 days monitored. Median AQI: 43 (Good).
Insights: Ashtabula County, Ohio. EPA monitors recorded a median Air Quality Index of 43 across 245 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 199 (81%) fell in the Good band (AQI 0–50), 43 (18%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 122 (USG). Residents averaged about 24.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (245 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -11.7 points and the median AQI moved +6 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 122, usg but never Unhealthy. Nearby counties show comparable readings: Allen (67.0% good, AQI 42); Athens (83.4% good, AQI 31); Belmont (63.0% good, AQI 42); Butler (33.1% good, AQI 55); Clark (61.4% good, AQI 45); Clermont (76.9% good, AQI 41).
Air Quality Summary
Good Days
81.2%
199 of 245 monitored days
6.2pp vs 75% target
Max AQI Recorded
122
USG
Health Grade
Good
90th-pct AQI 61
Ashtabula County, Good days share 81.2%
National avg
Share of monitored days at AQI 0-50 (Good band).
Ashtabula County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 245 monitored days across EPA AQI categories.
Good
199
81%
Moderate
43
18%
USG
3
1%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Ashtabula County.
- Ozone · 245 days · 100.0%
Health Impact Assessment
Good
Ashtabula County's air quality is rated Good based on 81.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 81.2% of monitored days in 2025, with a median AQI of 43. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 245 of 245 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Ashtabula County. Highest Good-day share: 2020 (92.9%, 224 of 241 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 224 | 17 | 0 | 0 | 37 | 93 |
| 2021 | 213 | 28 | 2 | 0 | 38 | 112 |
| 2022 | 211 | 23 | 5 | 0 | 38 | 133 |
| 2023 | 208 | 35 | 2 | 0 | 42 | 147 |
| 2024 | 205 | 38 | 2 | 0 | 41 | 108 |
| 2025 | 199 | 43 | 3 | 0 | 43 | 122 |
How does Ashtabula County compare?
How Ashtabula County compares
Good-day share better than US avg
Ashtabula County 81.2%
Baltimore (City) County, Maryland 68.1%
US average 76.0%
Median AQI worse than US avg
Ashtabula County 43
Baltimore (City) County, Maryland 43
US average 39
Unhealthy days / yr better than US avg
Ashtabula County 0
Baltimore (City) County, Maryland 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Ashtabula County (43), not geographic neighbors.
Baltimore (City) County, Maryland
Median AQI 43 · 68.1% Good-day share
Bartholomew County, Indiana
Median AQI 43 · 72.6% Good-day share
Berks County, Pennsylvania
Median AQI 43 · 68.2% Good-day share
Bolivar County, Mississippi
Median AQI 43 · 71.9% Good-day share
Brewster County, Texas
Median AQI 43 · 74.7% Good-day share
Broward County, Florida
Median AQI 43 · 73.4% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Essex County, Massachusetts
81.1% Good-day share · median AQI 40
Litchfield County, Connecticut
81.4% Good-day share · median AQI 39
Volusia County, Florida
81.4% Good-day share · median AQI 41
Coos County, New Hampshire
81.5% Good-day share · median AQI 44
Middlesex County, New Jersey
81.5% Good-day share · median AQI 36
Ohio County, West Virginia
80.9% Good-day share · median AQI 40
Ohio counties on the map
Geographic containment only, other monitored counties in Ohio, independent of AQI or pollutant match.
What Ashtabula County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 43 means for exposure. Health guidance
- See how Ashtabula County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Ashtabula County with its Ohio neighbours before drawing a conclusion about the region. All of Ohio
Based on 245 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Ashtabula County, Ohio? ▼
Ashtabula County has a median Air Quality Index (AQI) of 43, rated "Good." 81.2% of monitored days (199 out of 245) had good air quality in 2025.
What is the main pollutant in Ashtabula County? ▼
The primary pollutant in Ashtabula County is Ozone (O3), which was the main AQI driver on 245 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Ashtabula County have? ▼
In 2025, Ashtabula County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is the air quality in Ashtabula County getting better or worse? ▼
Air quality in Ashtabula County 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 92.9% (224 of 241 days). Lowest qualifying Good-day share: 2025 at 81.2% (199 of 245 days).
What does AQI 43 mean for health? ▼
Ashtabula County's median AQI of 43 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Ashtabula County compare to other counties in Ohio? ▼
Ashtabula County has 81.2% good air days. Nearby counties in Ohio: Allen (67.0% good), Athens (83.4% good), Belmont (63.0% good), Butler (33.1% good), Clark (61.4% good), Clermont (76.9% good).
What is the 90th percentile AQI in Ashtabula County? ▼
The 90th percentile AQI for Ashtabula County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 122 (USG).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Ashtabula County, Ohio · 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.