Median AQI
36
Good
Kentucky · County air quality · 2025
Perry County, Kentucky
Median AQI 36 (Good). 87.1% of monitored days rated Good, direct from EPA Air Quality System stations.
- 36
- Median AQI
- 87.1%
- Good-air days
- 1
- Unhealthy days
- 74%
- Cleaner than US counties
Perry County's 2025 annual median AQI is 36 (Good), with 87.1% Good days
According to the U.S. EPA Air Quality System, Perry County, Kentucky posted a 2025 median AQI of 36 (Good) across 365 monitored days, with 87.1% rated Good and 1 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 87.1% Good-day share places it cleaner than 74% 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 improving from 2020 to 2025 (76.4% → 87.1%).
- 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 the median US county, a median AQI of 36 with 87.1% of 365 monitored days in the Good band, driven mainly by PM2.5.
- 36
- median AQI · Good
- 87.1%
- days rated Good
- PM2.5
- main pollutant
- 74%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 172.
Annual release change
What changed in the 2025 EPA annual release
- Perry County's peak single-day AQI rose from 117 to 172 between the 2024 and 2025 EPA annual releases, a change of +55 points.
- Perry County's Good-day share rose from 82.4% to 87.1% between the 2024 and 2025 EPA annual releases, a change of +4.7 percentage points.
- Perry County's median AQI fell from 40 to 36 between the 2024 and 2025 EPA annual releases, a change of -4 points.
- Perry County's Unhealthy-category days rose from 0 to 1 between the 2024 and 2025 EPA annual releases, a change of +1 days.
Data updated August 2026
- Good · 318 d · 87.1%
- Moderate · 46 d · 12.6%
- Unhealthy · 1 d · 0.3%
How did Perry County's air break down in 2025?
Across 365 monitored days, 318 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 172 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 36 (Good).
Insights: Perry County, Kentucky. EPA monitors recorded a median Air Quality Index of 36 across 365 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 318 (87%) fell in the Good band (AQI 0–50), 46 (13%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 52, while the worst single-day peak hit 172 (Unhealthy). Residents averaged about 26.1 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (204 days), Ozone (161 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by +10.7 points and the median AQI moved -3 points, placing the multi-year trajectory at improving. The annual record contains 1 day at Unhealthy or worse. On that day, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Bell (67.0% good, AQI 42); Boone (87.6% good, AQI 38); Boyd (80.0% good, AQI 39); Bullitt (88.4% good, AQI 39); Campbell (75.6% good, AQI 39); Carter (89.0% good, AQI 36).
Air Quality Summary
Good Days
87.1%
318 of 365 monitored days
12.1pp vs 75% target
Max AQI Recorded
172
Unhealthy
Health Grade
Good
90th-pct AQI 52
Perry County, Good days share 87.1%
National avg
Share of monitored days at AQI 0-50 (Good band).
Perry County, Unhealthy-or-worse share 2.7%
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
318
87%
Moderate
46
13%
USG
0
0%
Unhealthy
1
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Perry County.
- PM2.5 · 204 days · 55.9%
- Ozone · 161 days · 44.1%
Health Impact Assessment
Good
Perry County's air quality is rated Good based on 87.1% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 0 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 172. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is PM2.5, driving AQI on 204 of 365 monitored days.
5-Year Air Quality Trend
Air quality is improving in Perry County. Highest Good-day share: 2025 (87.1%, 318 of 365 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 278 | 86 | 0 | 0 | 39 | 99 |
| 2021 | 247 | 118 | 0 | 0 | 44 | 93 |
| 2022 | 226 | 119 | 1 | 2 | 46 | 171 |
| 2023 | 223 | 138 | 4 | 0 | 45 | 137 |
| 2024 | 290 | 61 | 1 | 0 | 40 | 117 |
| 2025 | 318 | 46 | 0 | 1 | 36 | 172 |
How does Perry County compare?
How Perry County compares
Good-day share better than typical
Perry County 87.1%
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 about typical
Perry County 1
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: PM2.5
PM2.5 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).
Orange County, New York
86.9% Good-day share · median AQI 27
Whitman County, Washington
86.8% Good-day share · median AQI 23
Franklin County, Washington
86.7% Good-day share · median AQI 23
Clackamas County, Oregon
87.6% Good-day share · median AQI 31
Washington County, Nebraska
86.6% Good-day share · median AQI 27
Wyoming County, Pennsylvania
86.5% Good-day share · median AQI 24
Kentucky counties on the map
Geographic containment only, other monitored counties in Kentucky, independent of AQI or pollutant match.
What Perry County's air means for you
On most days the air here is fine, but PM2.5 drives 1 unhealthy-or-worse day a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 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 Kentucky neighbours before drawing a conclusion about the region. All of Kentucky
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 Perry County, Kentucky? ▼
Perry County has a median Air Quality Index (AQI) of 36, rated "Good." 87.1% of monitored days (318 out of 365) had good air quality in 2025.
What is the main pollutant in Perry County? ▼
The primary pollutant in Perry County is Fine Particles (PM2.5), which was the main AQI driver on 204 days (56% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Perry County have? ▼
In 2025, Perry County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 172.
Is the air quality in Perry County getting better or worse? ▼
Air quality in Perry County is improving across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2025 at 87.1% (318 of 365 days). Lowest qualifying Good-day share: 2023 at 61.1% (223 of 365 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 Kentucky? ▼
Perry County has 87.1% good air days. Nearby counties in Kentucky: Bell (67.0% good), Boone (87.6% good), Boyd (80.0% good), Bullitt (88.4% good), Campbell (75.6% good), Carter (89.0% good).
What is the 90th percentile AQI in Perry County? ▼
The 90th percentile AQI for Perry County is 52, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 172 (Unhealthy).
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, Kentucky · 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.