Median AQI
46
Good
Pennsylvania · County air quality · 2025
Lancaster County, Pennsylvania
Median AQI 46 (Good). 60.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 46
- Median AQI
- 60.0%
- Good-air days
- 0
- Unhealthy days
- 15%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Lancaster County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 46 with 60.0% of 210 monitored days in the Good band, driven mainly by PM2.5.
- 46
- median AQI · Good
- 60.0%
- days rated Good
- PM2.5
- main pollutant
- 15%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 119.
Data updated July 2026
- Good · 126 d · 60.0%
- Moderate · 82 d · 39.0%
- USG · 2 d · 1.0%
How did Lancaster County's air break down in 2025?
Across 210 monitored days, 126 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 119 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 210 days monitored. Median AQI: 46 (Good).
Insights: Lancaster County, Pennsylvania. EPA monitors recorded a median Air Quality Index of 46 across 210 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 126 (60%) fell in the Good band (AQI 0–50), 82 (39%) registered Moderate readings, and 2 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 72, while the worst single-day peak hit 119 (USG). Residents averaged about 18.0 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (109 days), Ozone (101 days). Across the 2020–2025 trend window, good days shifted by -51 and the median AQI moved -5 points, placing the multi-year trajectory at improving. The worst single reading over the 2020–2025 window was AQI 119, 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
60.0%
126 of 210 monitored days
-15.0pp vs 75% target
Max AQI Recorded
119
USG
Health Grade
Moderate
90th-pct AQI 72
Lancaster County, Good days share 60.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Lancaster 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 210 monitored days across EPA AQI categories.
Good
126
60%
Moderate
82
39%
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 Lancaster County.
- PM2.5 · 109 days · 51.9%
- Ozone · 101 days · 48.1%
Health Impact Assessment
Moderate
Lancaster County's air quality is rated Moderate based on 60.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 60.0% of monitored days in 2025, with a median AQI of 46. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 109 of 210 monitored days.
5-Year Air Quality Trend
Air quality is improving in Lancaster County. Best year: 2024 (189 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 177 | 184 | 4 | 1 | 51 | 153 |
| 2021 | 100 | 257 | 7 | 1 | 56 | 156 |
| 2022 | 84 | 274 | 6 | 1 | 59 | 153 |
| 2023 | 108 | 243 | 9 | 3 | 58 | 321 |
| 2024 | 189 | 174 | 3 | 0 | 50 | 125 |
| 2025 | 126 | 82 | 2 | 0 | 46 | 119 |
How does Lancaster County compare?
How Lancaster County compares
Good-day share worse than US avg
Lancaster County 60.0%
Adams County, Pennsylvania 73.8%
US average 76.5%
Median AQI worse than US avg
Lancaster County 46
Adams County, Pennsylvania 42
US average 38
Unhealthy days / yr about average
Lancaster 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 Lancaster County.
Bay County, Florida
AQI 46 · 60.6% good
Blount County, Tennessee
AQI 46 · 69.6% good
Cache County, Utah
AQI 46 · 61.2% good
Chesterfield County, South Carolina
AQI 46 · 61.2% good
Clark County, Indiana
AQI 46 · 59.7% good
Clark County, Ohio
AQI 46 · 59.4% good
What Lancaster County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 46 means for exposure. Health guidance
- See how Lancaster County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Lancaster County with its Pennsylvania neighbours before drawing a conclusion about the region. All of Pennsylvania
Based on 210 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 Lancaster County, Pennsylvania? ▼
Lancaster County has a median Air Quality Index (AQI) of 46, rated "Good." 60.0% of monitored days (126 out of 210) had good air quality in 2025.
What is the main pollutant in Lancaster County? ▼
The primary pollutant in Lancaster County is Fine Particles (PM2.5), which was the main AQI driver on 109 days (52% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Lancaster County have? ▼
In 2025, Lancaster County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 119.
Is the air quality in Lancaster County getting better or worse? ▼
Air quality in Lancaster County is improving based on 5-year trends (2020-2025). Best year: 2024 with 189 good days. Worst year: 2022 with 84 good days.
What does AQI 46 mean for health? ▼
Lancaster County's median AQI of 46 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 Lancaster County compare to other counties in Pennsylvania? ▼
Lancaster County has 60.0% 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 Lancaster County? ▼
The 90th percentile AQI for Lancaster County is 72, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 119 (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.