Median AQI
31
Good
Pennsylvania · County air quality · 2025
Erie County, Pennsylvania
Median AQI 31 (Good). 81.4% of monitored days rated Good, direct from EPA Air Quality System stations.
- 31
- Median AQI
- 81.4%
- Good-air days
- 0
- Unhealthy days
- 56%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Erie County's air is good on balance, cleaner than the median US county, a median AQI of 31 with 81.4% of 274 monitored days in the Good band, driven mainly by PM2.5.
- 31
- median AQI · Good
- 81.4%
- days rated Good
- PM2.5
- main pollutant
- 56%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 99.
Data updated July 2026
- Good · 223 d · 81.4%
- Moderate · 51 d · 18.6%
How did Erie County's air break down in 2025?
Across 274 monitored days, 223 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 99 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 274 days monitored. Median AQI: 31 (Good).
Insights: Erie County, Pennsylvania. EPA monitors recorded a median Air Quality Index of 31 across 274 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 223 (81%) fell in the Good band (AQI 0–50), 51 (19%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 58, while the worst single-day peak hit 99 (Moderate). Residents averaged about 24.4 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (149 days), CO (64 days), Ozone (54 days), NO2 (7 days). Across the 2020–2025 trend window, good days shifted by -75 and the median AQI moved -5 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 99, moderate 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
81.4%
223 of 274 monitored days
6.4pp vs 75% target
Max AQI Recorded
99
Moderate
Health Grade
Good
90th-pct AQI 58
Erie County, Good days share 81.4%
National avg
Share of monitored days at AQI 0-50 (Good band).
Erie 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 274 monitored days across EPA AQI categories.
Good
223
81%
Moderate
51
19%
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 Erie County.
- PM2.5 · 149 days · 54.4%
- CO · 64 days · 23.4%
- Ozone · 54 days · 19.7%
- NO₂ · 7 days · 2.6%
Health Impact Assessment
Good
Erie County's air quality is rated Good based on 81.4% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 81.4% of monitored days in 2025, with a median AQI of 31. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 149 of 274 monitored days.
5-Year Air Quality Trend
Air quality is stable in Erie County. Best year: 2020 (298 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 298 | 65 | 0 | 0 | 36 | 87 |
| 2021 | 255 | 74 | 0 | 0 | 38 | 92 |
| 2022 | 286 | 79 | 0 | 0 | 38 | 90 |
| 2023 | 240 | 116 | 6 | 3 | 42 | 180 |
| 2024 | 295 | 71 | 0 | 0 | 38 | 93 |
| 2025 | 223 | 51 | 0 | 0 | 31 | 99 |
How does Erie County compare?
How Erie County compares
Good-day share better than US avg
Erie County 81.4%
Adams County, Pennsylvania 73.8%
US average 76.5%
Median AQI better than US avg
Erie County 31
Adams County, Pennsylvania 42
US average 38
Unhealthy days / yr about average
Erie 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 Erie County.
Bannock County, Idaho
AQI 31 · 91.5% good
Clark County, Washington
AQI 31 · 89.3% good
Honolulu County, Hawaii
AQI 31 · 95.0% good
Josephine County, Oregon
AQI 31 · 76.2% good
Monroe County, Wisconsin
AQI 31 · 75.2% good
Montgomery County, Tennessee
AQI 31 · 84.7% good
What Erie 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 31 means for exposure. Health guidance
- See how Erie County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Erie County with its Pennsylvania neighbours before drawing a conclusion about the region. All of Pennsylvania
Based on 274 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 Erie County, Pennsylvania? ▼
Erie County has a median Air Quality Index (AQI) of 31, rated "Good." 81.4% of monitored days (223 out of 274) had good air quality in 2025.
What is the main pollutant in Erie County? ▼
The primary pollutant in Erie County is Fine Particles (PM2.5), which was the main AQI driver on 149 days (54% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Erie County have? ▼
In 2025, Erie County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 99.
Is the air quality in Erie County getting better or worse? ▼
Air quality in Erie County is stable based on 5-year trends (2020-2025). Best year: 2020 with 298 good days. Worst year: 2025 with 223 good days.
What does AQI 31 mean for health? ▼
Erie County's median AQI of 31 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 Erie County compare to other counties in Pennsylvania? ▼
Erie County has 81.4% 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 Erie County? ▼
The 90th percentile AQI for Erie County is 58, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 99 (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.
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.