Median AQI
39
Good
Maine · County air quality · 2025
Oxford County, Maine
Median AQI 39 (Good). 74.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 74.0%
- Good-air days
- 0
- Unhealthy days
- 39%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Oxford County's air is good on balance, more polluted than the median US county, a median AQI of 39 with 74.0% of 304 monitored days in the Good band, driven mainly by PM2.5.
- 39
- median AQI · Good
- 74.0%
- days rated Good
- PM2.5
- main pollutant
- 39%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 135.
Data updated July 2026
- Good · 225 d · 74.0%
- Moderate · 76 d · 25.0%
- USG · 3 d · 1.0%
How did Oxford County's air break down in 2025?
Across 304 monitored days, 225 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 135 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 304 days monitored. Median AQI: 39 (Good).
Insights: Oxford County, Maine. EPA monitors recorded a median Air Quality Index of 39 across 304 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 225 (74%) fell in the Good band (AQI 0–50), 76 (25%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 61, while the worst single-day peak hit 135 (USG). Residents averaged about 22.2 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (199 days), Ozone (105 days). Across the 2020–2025 trend window, good days shifted by -74 and the median AQI moved +3 points, placing the multi-year trajectory at worsening. The worst single reading over the 2020–2025 window was AQI 135, usg but never Unhealthy. Nearby counties show comparable readings: Androscoggin (85.5% good, AQI 35); Aroostook (84.1% good, AQI 36); Cumberland (74.0% good, AQI 39); Hancock (89.1% good, AQI 37); Kennebec (83.5% good, AQI 36); Knox (97.3% good, AQI 34).
Air Quality Summary
Good Days
74.0%
225 of 304 monitored days
-1.0pp vs 75% target
Max AQI Recorded
135
USG
Health Grade
Moderate
90th-pct AQI 61
Oxford County, Good days share 74.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Oxford 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 304 monitored days across EPA AQI categories.
Good
225
74%
Moderate
76
25%
USG
3
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 Oxford County.
- PM2.5 · 199 days · 65.5%
- Ozone · 105 days · 34.5%
Health Impact Assessment
Moderate
Oxford County's air quality is rated Moderate based on 74.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 74.0% 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 199 of 304 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Oxford County. Best year: 2024 (326 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 299 | 25 | 0 | 0 | 36 | 69 |
| 2021 | 308 | 51 | 1 | 0 | 35 | 113 |
| 2022 | 324 | 34 | 0 | 0 | 33 | 96 |
| 2023 | 288 | 68 | 0 | 0 | 38 | 83 |
| 2024 | 326 | 38 | 0 | 0 | 32 | 71 |
| 2025 | 225 | 76 | 3 | 0 | 39 | 135 |
How does Oxford County compare?
How Oxford County compares
Good-day share worse than US avg
Oxford County 74.0%
Androscoggin County, Maine 85.5%
US average 76.5%
Median AQI worse than US avg
Oxford County 39
Androscoggin County, Maine 35
US average 38
Unhealthy days / yr about average
Oxford County 0
Androscoggin County, Maine 0
US average 0
Other Counties in Maine
Air quality comparison for nearby counties in Maine.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Oxford 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 Oxford 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 Oxford County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Oxford County with its Maine neighbours before drawing a conclusion about the region. All of Maine
Based on 304 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 Oxford County, Maine? ▼
Oxford County has a median Air Quality Index (AQI) of 39, rated "Good." 74.0% of monitored days (225 out of 304) had good air quality in 2025.
What is the main pollutant in Oxford County? ▼
The primary pollutant in Oxford County is Fine Particles (PM2.5), which was the main AQI driver on 199 days (65% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Oxford County have? ▼
In 2025, Oxford County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 135.
Is the air quality in Oxford County getting better or worse? ▼
Air quality in Oxford County is worsening based on 5-year trends (2020-2025). Best year: 2024 with 326 good days. Worst year: 2025 with 225 good days.
What does AQI 39 mean for health? ▼
Oxford 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 Oxford County compare to other counties in Maine? ▼
Oxford County has 74.0% good air days. Nearby counties in Maine: Androscoggin (85.5% good), Aroostook (84.1% good), Cumberland (74.0% good), Hancock (89.1% good), Kennebec (83.5% good), Knox (97.3% good).
What is the 90th percentile AQI in Oxford County? ▼
The 90th percentile AQI for Oxford County is 61, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 135 (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.