Pennsylvania · County air quality · 2025
Warren County, Pennsylvania
Median AQI 35 (Good). 78.7% of monitored days rated Good, direct from EPA Air Quality System stations.
- 35
- Median AQI
- 78.7%
- Good-air days
- 0
- Unhealthy days
- 52%
- Cleaner than US counties
Warren County's 2025 annual median AQI is 35 (Good), with 78.7% Good days
According to the U.S. EPA Air Quality System, Warren County, Pennsylvania posted a 2025 median AQI of 35 (Good) across 150 monitored days, with 78.7% 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
- Warren County's 78.7% Good-day share places it cleaner than 52% of US counties in 2025.
- Closest median-AQI peer
- Atascosa County (76.0% Good, median AQI 35) is the closest nationwide median-AQI peer to Warren County.
- Median AQI
- Median AQI: 35
- Good days
- Good days: 78.7%
According to the 2025 EPA AQS county release on PlainAirData, Warren County, Pennsylvania ranks #191 of 951 by median AQI (35) and #452 by good-day share (78.7%). Ponce County, Puerto Rico is #1 of 951 by median AQI (3, 91.4% Good days) at good-day-share #159 ≠ largest of 7 at 100.0% Good days #1 by good-day share (100.0%, median AQI 9) at median-AQI #7.
Data updated August 2026
- Good · 118 d · 78.7%
- Moderate · 29 d · 19.3%
- USG · 3 d · 2.0%
How did Warren County's air break down in 2025?
Across 150 monitored days, 118 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 138 (USG).
EPA AQS →Share of monitored days at AQI 0-50 (Good band).
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
Where Warren County sits nationally
COUNT-derived placement among 951 US counties with at least 100 monitored days in 2025. Warren County's Good-day share is 78.7% - cleaner than 52% of that comparison set.
Warren County Good-day share vs. every US county
Share of monitored days in the Good band (AQI 0–50) - EPA AQS annual release
78.7% Cleaner than 52% higher than 52% of 951 US counties
Each bar is a band; taller bars hold more US counties. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.
Source U.S. Environmental Protection Agency, Air Quality System (AQS) · 2025
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Warren County.
- Ozone · 92 days · 61.3%
- PM2.5 · 58 days · 38.7%
Health Impact Assessment
Warren County's air quality is rated Good based on 78.7% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 78.7% of monitored days in 2025, with a median AQI of 35. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 92 of 150 monitored days.
How does Warren County compare?
How Warren County compares
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 Warren County, Pennsylvania · 2020–2025
Download this county's annual AQI row as CSV , with the same EPA fields and denominator shown on this page.
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.