Median AQI
39
Good
Pennsylvania · County air quality · 2025
Northampton County, Pennsylvania
Median AQI 39 (Good). 70.8% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 70.8%
- Good-air days
- 0
- Unhealthy days
- 33%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Northampton County's air is good on balance, more polluted than the median US county, a median AQI of 39 with 70.8% of 212 monitored days in the Good band, driven mainly by PM2.5.
- 39
- median AQI · Good
- 70.8%
- days rated Good
- PM2.5
- main pollutant
- 33%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 122.
Data updated July 2026
- Good · 150 d · 70.8%
- Moderate · 61 d · 28.8%
- USG · 1 d · 0.5%
How did Northampton County's air break down in 2025?
Across 212 monitored days, 150 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 122 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 212 days monitored. Median AQI: 39 (Good).
Insights: Northampton County, Pennsylvania. EPA monitors recorded a median Air Quality Index of 39 across 212 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 150 (71%) fell in the Good band (AQI 0–50), 61 (29%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 62, while the worst single-day peak hit 122 (USG). Residents averaged about 21.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (107 days), Ozone (102 days), NO2 (3 days). Across the 2020–2025 trend window, good days shifted by -110 and the median AQI moved -2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 122, 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
70.8%
150 of 212 monitored days
-4.3pp vs 75% target
Max AQI Recorded
122
USG
Health Grade
Moderate
90th-pct AQI 62
Northampton County, Good days share 70.8%
National avg
Share of monitored days at AQI 0-50 (Good band).
Northampton 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
150
71%
Moderate
61
29%
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 Northampton County.
- PM2.5 · 107 days · 50.5%
- Ozone · 102 days · 48.1%
- NO₂ · 3 days · 1.4%
Health Impact Assessment
Moderate
Northampton County's air quality is rated Moderate based on 70.8% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 70.8% of monitored days in 2025, with a median AQI of 39. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 107 of 212 monitored days.
5-Year Air Quality Trend
Air quality is stable in Northampton County. Best year: 2024 (278 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 260 | 104 | 1 | 0 | 41 | 117 |
| 2021 | 214 | 147 | 4 | 0 | 45 | 148 |
| 2022 | 224 | 132 | 2 | 0 | 45 | 118 |
| 2023 | 209 | 146 | 2 | 4 | 46 | 368 |
| 2024 | 278 | 87 | 1 | 0 | 39 | 105 |
| 2025 | 150 | 61 | 1 | 0 | 39 | 122 |
How does Northampton County compare?
How Northampton County compares
Good-day share worse than US avg
Northampton County 70.8%
Adams County, Pennsylvania 73.8%
US average 76.5%
Median AQI worse than US avg
Northampton County 39
Adams County, Pennsylvania 42
US average 38
Unhealthy days / yr about average
Northampton 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 Northampton County.
Ada County, Idaho
AQI 39 · 80.6% good
Aiken County, South Carolina
AQI 39 · 89.1% good
Albany County, New York
AQI 39 · 67.4% good
Alexander County, North Carolina
AQI 39 · 92.4% good
Ashland County, Wisconsin
AQI 39 · 85.6% good
Bennington County, Vermont
AQI 39 · 82.9% good
What Northampton 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 39 means for exposure. Health guidance
- See how Northampton County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Northampton 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 Northampton County, Pennsylvania? ▼
Northampton County has a median Air Quality Index (AQI) of 39, rated "Good." 70.8% of monitored days (150 out of 212) had good air quality in 2025.
What is the main pollutant in Northampton County? ▼
The primary pollutant in Northampton County is Fine Particles (PM2.5), which was the main AQI driver on 107 days (50% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Northampton County have? ▼
In 2025, Northampton County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 122.
Is the air quality in Northampton County getting better or worse? ▼
Air quality in Northampton County is stable based on 5-year trends (2020-2025). Best year: 2024 with 278 good days. Worst year: 2025 with 150 good days.
What does AQI 39 mean for health? ▼
Northampton County's median AQI of 39 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 Northampton County compare to other counties in Pennsylvania? ▼
Northampton County has 70.8% 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 Northampton County? ▼
The 90th percentile AQI for Northampton County is 62, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 122 (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.