Median AQI
43
Good
Ohio · County air quality · 2025
Preble County, Ohio
Median AQI 43 (Good). 67.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 43
- Median AQI
- 67.7%
- Good-air days
- 0
- Unhealthy days
- 27%
- Cleaner than US counties
Preble County's 2025 annual median AQI is 43 (Good), with 67.7% Good days
According to the U.S. EPA Air Quality System, Preble County, Ohio posted a 2025 median AQI of 43 (Good) across 365 monitored days, with 67.7% 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
- Preble County's 67.7% Good-day share places it cleaner than 27% of US counties in 2025.
- Closest median-AQI peer
- Ashtabula County (81.2% Good, median AQI 43) is the closest nationwide median-AQI peer to Preble County.
- 2020–2025 trend
- Preble County's floor-qualifying Good-day share is worsening from 2020 to 2025 (71.6% → 67.7%).
- Median AQI
- Median AQI: 43
The verdict
According to EPA Air Quality System monitoring data, Preble County's air is good on balance, more polluted than the median US county, a median AQI of 43 with 67.7% of 365 monitored days in the Good band, driven mainly by Ozone.
- 43
- median AQI · Good
- 67.7%
- days rated Good
- Ozone
- main pollutant
- 27%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 115.
Annual release change
What changed in the 2025 EPA annual release
- Preble County's peak single-day AQI rose from 100 to 115 between the 2024 and 2025 EPA annual releases, a change of +15 points.
- Preble County's Good-day share fell from 68.9% to 67.7% between the 2024 and 2025 EPA annual releases, a change of -1.2 percentage points.
Data updated August 2026
- Good · 247 d · 67.7%
- Moderate · 116 d · 31.8%
- USG · 2 d · 0.5%
How did Preble County's air break down in 2025?
Across 365 monitored days, 247 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 115 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 43 (Good).
Insights: Preble County, Ohio. EPA monitors recorded a median Air Quality Index of 43 across 365 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 247 (68%) fell in the Good band (AQI 0–50), 116 (32%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 64, while the worst single-day peak hit 115 (USG). Residents averaged about 20.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (199 days), PM2.5 (164 days), PM10 (1 days), CO (1 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -3.9 points and the median AQI moved +1 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 115, usg but never Unhealthy. Nearby counties show comparable readings: Allen (67.0% good, AQI 42); Ashtabula (81.2% good, AQI 43); Athens (83.4% good, AQI 31); Belmont (63.0% good, AQI 42); Butler (33.1% good, AQI 55); Clark (61.4% good, AQI 45).
Air Quality Summary
Good Days
67.7%
247 of 365 monitored days
-7.3pp vs 75% target
Max AQI Recorded
115
USG
Health Grade
Moderate
90th-pct AQI 64
Preble County, Good days share 67.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Preble 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 365 monitored days across EPA AQI categories.
Good
247
68%
Moderate
116
32%
USG
2
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 Preble County.
- Ozone · 199 days · 54.5%
- PM2.5 · 164 days · 44.9%
- PM10 · 1 days · 0.3%
- CO · 1 days · 0.3%
Health Impact Assessment
Moderate
Preble County's air quality is rated Moderate based on 67.7% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 67.7% 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 199 of 365 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Preble County. Highest Good-day share: 2020 (71.6%, 262 of 366 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 262 | 103 | 1 | 0 | 42 | 101 |
| 2021 | 205 | 160 | 0 | 0 | 47 | 97 |
| 2022 | 235 | 128 | 2 | 0 | 44 | 136 |
| 2023 | 213 | 136 | 6 | 2 | 46 | 204 |
| 2024 | 252 | 114 | 0 | 0 | 44 | 100 |
| 2025 | 247 | 116 | 2 | 0 | 43 | 115 |
How does Preble County compare?
How Preble County compares
Good-day share worse than typical
Preble County 67.7%
Ashtabula County, Ohio 81.2%
Typical US county 76.0%
Median AQI worse than typical
Preble County 43
Ashtabula County, Ohio 43
Typical US county 39
Unhealthy days / yr better than typical
Preble County 0
Ashtabula County, Ohio 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Preble County (43), not geographic neighbors.
Ashtabula County, Ohio
Median AQI 43 · 81.2% Good-day share
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
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).
Douglas County, Colorado
67.7% Good-day share · median AQI 46
Washington County, Pennsylvania
67.7% Good-day share · median AQI 44
Warren County, Ohio
67.9% Good-day share · median AQI 44
Clear Creek County, Colorado
67.9% Good-day share · median AQI 48
Hartford County, Connecticut
68.0% Good-day share · median AQI 42
San Juan County, New Mexico
68.0% Good-day share · median AQI 47
Ohio counties on the map
Geographic containment only, other monitored counties in Ohio, independent of AQI or pollutant match.
What Preble 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 Preble County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Preble County with its Ohio neighbours before drawing a conclusion about the region. All of Ohio
Based on 365 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 Preble County, Ohio? ▼
Preble County has a median Air Quality Index (AQI) of 43, rated "Good." 67.7% of monitored days (247 out of 365) had good air quality in 2025.
What is the main pollutant in Preble County? ▼
The primary pollutant in Preble County is Ozone (O3), which was the main AQI driver on 199 days (55% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Preble County have? ▼
In 2025, Preble County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 115.
Is the air quality in Preble County getting better or worse? ▼
Air quality in Preble 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 71.6% (262 of 366 days). Lowest qualifying Good-day share: 2021 at 56.2% (205 of 365 days).
What does AQI 43 mean for health? ▼
Preble 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 Preble County compare to other counties in Ohio? ▼
Preble County has 67.7% good air days. Nearby counties in Ohio: Allen (67.0% good), Ashtabula (81.2% good), Athens (83.4% good), Belmont (63.0% good), Butler (33.1% good), Clark (61.4% good).
What is the 90th percentile AQI in Preble County? ▼
The 90th percentile AQI for Preble County is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 115 (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 Preble 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.