Median AQI
45
Good
Pennsylvania · County air quality · 2025
York County, Pennsylvania
Median AQI 45 (Good). 65.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 65.6%
- Good-air days
- 0
- Unhealthy days
- 23%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, York County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 65.6% of 212 monitored days in the Good band, driven mainly by Ozone.
- 45
- median AQI · Good
- 65.6%
- days rated Good
- Ozone
- main pollutant
- 23%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 101.
Data updated July 2026
- Good · 139 d · 65.6%
- Moderate · 72 d · 34.0%
- USG · 1 d · 0.5%
How did York County's air break down in 2025?
Across 212 monitored days, 139 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 101 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 212 days monitored. Median AQI: 45 (Good).
Insights: York County, Pennsylvania. EPA monitors recorded a median Air Quality Index of 45 across 212 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 139 (66%) fell in the Good band (AQI 0–50), 72 (34%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 66, while the worst single-day peak hit 101 (USG). Residents averaged about 19.7 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (116 days), PM2.5 (95 days), NO2 (1 days). Across the 2020–2025 trend window, good days shifted by -82 and the median AQI moved -1 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 101, usg but never Unhealthy. Nearby counties show comparable readings: Adams (73.8% good, AQI 42); Allegheny (51.6% good, AQI 49); Armstrong (68.1% good, AQI 42); Beaver (54.3% good, AQI 47); Berks (65.6% good, AQI 44); Blair (71.9% good, AQI 41).
Air Quality Summary
Good Days
65.6%
139 of 212 monitored days
-9.4pp vs 75% target
Max AQI Recorded
101
USG
Health Grade
Moderate
90th-pct AQI 66
York County, Good days share 65.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
York 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 212 monitored days across EPA AQI categories.
Good
139
66%
Moderate
72
34%
USG
1
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 York County.
- Ozone · 116 days · 54.7%
- PM2.5 · 95 days · 44.8%
- NO₂ · 1 days · 0.5%
Health Impact Assessment
Moderate
York County's air quality is rated Moderate based on 65.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 65.6% of monitored days in 2025, with a median AQI of 45. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 116 of 212 monitored days.
5-Year Air Quality Trend
Air quality is improving in York County. Best year: 2024 (240 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 221 | 145 | 0 | 0 | 46 | 97 |
| 2021 | 168 | 187 | 2 | 0 | 51 | 148 |
| 2022 | 205 | 159 | 1 | 0 | 47 | 105 |
| 2023 | 198 | 150 | 4 | 3 | 48 | 256 |
| 2024 | 240 | 125 | 1 | 0 | 44 | 101 |
| 2025 | 139 | 72 | 1 | 0 | 45 | 101 |
How does York County compare?
How York County compares
Good-day share worse than US avg
York County 65.6%
Adams County, Pennsylvania 73.8%
US average 76.5%
Median AQI worse than US avg
York County 45
Adams County, Pennsylvania 42
US average 38
Unhealthy days / yr about average
York County 0
Adams County, Pennsylvania 0
US average 0
Other Counties in Pennsylvania
Air quality comparison for nearby counties in Pennsylvania.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to York County.
Adair County, Oklahoma
AQI 45 · 59.2% good
Allen County, Indiana
AQI 45 · 58.2% good
Atascosa County, Texas
AQI 45 · 58.0% good
Baker County, Florida
AQI 45 · 69.1% good
Carson City County, Nevada
AQI 45 · 79.3% good
Clinton County, Iowa
AQI 45 · 59.9% good
What York 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 45 means for exposure. Health guidance
- See how York County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare York County with its Pennsylvania neighbours before drawing a conclusion about the region. All of Pennsylvania
Based on 212 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in York County, Pennsylvania? ▼
York County has a median Air Quality Index (AQI) of 45, rated "Good." 65.6% of monitored days (139 out of 212) had good air quality in 2025.
What is the main pollutant in York County? ▼
The primary pollutant in York County is Ozone (O3), which was the main AQI driver on 116 days (55% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does York County have? ▼
In 2025, York County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 101.
Is the air quality in York County getting better or worse? ▼
Air quality in York County is improving based on 5-year trends (2020-2025). Best year: 2024 with 240 good days. Worst year: 2025 with 139 good days.
What does AQI 45 mean for health? ▼
York County's median AQI of 45 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does York County compare to other counties in Pennsylvania? ▼
York County has 65.6% good air days. Nearby counties in Pennsylvania: Adams (73.8% good), Allegheny (51.6% good), Armstrong (68.1% good), Beaver (54.3% good), Berks (65.6% good), Blair (71.9% good).
What is the 90th percentile AQI in York County? ▼
The 90th percentile AQI for York County is 66, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 101 (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.
Every figure on PlainAir 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.