Median AQI
36
Good
Indiana · County air quality · 2025
Perry County, Indiana
Median AQI 36 (Good). 92.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 36
- Median AQI
- 92.7%
- Good-air days
- 0
- Unhealthy days
- 86%
- Cleaner than US counties
Perry County's 2025 annual median AQI is 36 (Good), with 92.7% Good days
According to the U.S. EPA Air Quality System, Perry County, Indiana posted a 2025 median AQI of 36 (Good) across 317 monitored days, with 92.7% 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
- Perry County's 92.7% Good-day share places it cleaner than 86% of US counties in 2025.
- Closest median-AQI peer
- Ashland County (81.6% Good, median AQI 36) is the closest nationwide median-AQI peer to Perry County.
- 2020–2025 trend
- Perry County's floor-qualifying Good-day share is worsening from 2020 to 2025 (96.2% → 92.7%).
- Median AQI
- Median AQI: 36
The verdict
According to EPA Air Quality System monitoring data, Perry County's air is good on balance, cleaner than most US counties, a median AQI of 36 with 92.7% of 317 monitored days in the Good band, driven mainly by Ozone.
- 36
- median AQI · Good
- 92.7%
- days rated Good
- Ozone
- main pollutant
- 86%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 84.
Annual release change
What changed in the 2025 EPA annual release
- Perry County's Good-day share rose from 86.7% to 92.7% between the 2024 and 2025 EPA annual releases, a change of +6.1 percentage points.
- Perry County's median AQI fell from 39 to 36 between the 2024 and 2025 EPA annual releases, a change of -3 points.
Data updated August 2026
- Good · 294 d · 92.7%
- Moderate · 23 d · 7.3%
How did Perry County's air break down in 2025?
Across 317 monitored days, 294 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 84 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 317 days monitored. Median AQI: 36 (Good).
Insights: Perry County, Indiana. EPA monitors recorded a median Air Quality Index of 36 across 317 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 294 (93%) fell in the Good band (AQI 0–50), 23 (7%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 49, while the worst single-day peak hit 84 (Moderate). Residents averaged about 27.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (317 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -3.4 points (measured against 366 monitored days in 2020 and 317 in 2025, so raw day counts are not comparable) and the median AQI moved +2 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 84, moderate but never Unhealthy. Nearby counties show comparable readings: Allen (60.0% good, AQI 44); Bartholomew (72.6% good, AQI 43); Boone (89.7% good, AQI 35); Brown (95.9% good, AQI 34); Carroll (90.8% good, AQI 35); Clark (58.1% good, AQI 46).
Air Quality Summary
Good Days
92.7%
294 of 317 monitored days
17.7pp vs 75% target
Max AQI Recorded
84
Moderate
Health Grade
Excellent
90th-pct AQI 49
Perry County, Good days share 92.7%
National avg
Share of monitored days at AQI 0-50 (Good band).
Perry 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 317 monitored days across EPA AQI categories.
Good
294
93%
Moderate
23
7%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Perry County.
- Ozone · 317 days · 100.0%
Health Impact Assessment
Excellent
Perry County's air quality is rated Excellent based on 92.7% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 92.7% of monitored days in 2025, with a median AQI of 36. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 317 of 317 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Perry County. Highest Good-day share: 2020 (96.2%, 352 of 366 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 352 | 13 | 1 | 0 | 34 | 105 |
| 2021 | 334 | 29 | 0 | 0 | 36 | 97 |
| 2022 | 344 | 20 | 1 | 0 | 36 | 119 |
| 2023 | 318 | 37 | 2 | 0 | 38 | 112 |
| 2024 | 286 | 44 | 0 | 0 | 39 | 90 |
| 2025 | 294 | 23 | 0 | 0 | 36 | 84 |
How does Perry County compare?
How Perry County compares
Good-day share better than typical
Perry County 92.7%
Ashland County, Wisconsin 81.6%
Typical US county 76.0%
Median AQI better than typical
Perry County 36
Ashland County, Wisconsin 36
Typical US county 39
Unhealthy days / yr better than typical
Perry County 0
Ashland County, Wisconsin 8
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Perry County (36), not geographic neighbors.
Ashland County, Wisconsin
Median AQI 36 · 81.6% Good-day share
Atlantic County, New Jersey
Median AQI 36 · 82.2% Good-day share
Bannock County, Idaho
Median AQI 36 · 88.8% Good-day share
Barnstable County, Massachusetts
Median AQI 36 · 93.7% Good-day share
Beltrami County, Minnesota
Median AQI 36 · 79.1% Good-day share
Benton County, Washington
Median AQI 36 · 80.3% 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).
Kent County, Rhode Island
92.8% Good-day share · median AQI 31
Johnson County, Wyoming
92.8% Good-day share · median AQI 41
Pasco County, Florida
92.6% Good-day share · median AQI 37
Niagara County, New York
92.9% Good-day share · median AQI 34
Douglas County, Kansas
92.9% Good-day share · median AQI 37
Greenbrier County, West Virginia
93.0% Good-day share · median AQI 37
Indiana counties on the map
Geographic containment only, other monitored counties in Indiana, independent of AQI or pollutant match.
What Perry 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 36 means for exposure. Health guidance
- See how Perry County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Perry County with its Indiana neighbours before drawing a conclusion about the region. All of Indiana
Based on 317 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 Perry County, Indiana? ▼
Perry County has a median Air Quality Index (AQI) of 36, rated "Good." 92.7% of monitored days (294 out of 317) had good air quality in 2025.
What is the main pollutant in Perry County? ▼
The primary pollutant in Perry County is Ozone (O3), which was the main AQI driver on 317 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Perry County have? ▼
In 2025, Perry County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 84.
Is the air quality in Perry County getting better or worse? ▼
Air quality in Perry 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 96.2% (352 of 366 days). Lowest qualifying Good-day share: 2024 at 86.7% (286 of 330 days).
What does AQI 36 mean for health? ▼
Perry County's median AQI of 36 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Perry County compare to other counties in Indiana? ▼
Perry County has 92.7% good air days. Nearby counties in Indiana: Allen (60.0% good), Bartholomew (72.6% good), Boone (89.7% good), Brown (95.9% good), Carroll (90.8% good), Clark (58.1% good).
What is the 90th percentile AQI in Perry County? ▼
The 90th percentile AQI for Perry County is 49, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 84 (Moderate).
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 Perry County, Indiana · 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.