Median AQI
35
Good
Maine · County air quality · 2025
Hancock County, Maine
Median AQI 35 (Good). 91.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 35
- Median AQI
- 91.0%
- Good-air days
- 0
- Unhealthy days
- 82%
- Cleaner than US counties
Hancock County's 2025 annual median AQI is 35 (Good), with 91.0% Good days
According to the U.S. EPA Air Quality System, Hancock County, Maine posted a 2025 median AQI of 35 (Good) across 365 monitored days, with 91.0% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Hancock County's 91.0% Good-day share places it cleaner than 82% of US counties in 2025.
- Closest median-AQI peer
- Atascosa County (76.0% Good, median AQI 35) is the closest nationwide median-AQI peer to Hancock County.
- 2020–2025 trend
- Hancock County's floor-qualifying Good-day share is stable from 2020 to 2025 (91.8% → 91.0%).
- Median AQI
- Median AQI: 35
The verdict
According to EPA Air Quality System monitoring data, Hancock County's air is good on balance, cleaner than most US counties, a median AQI of 35 with 91.0% of 365 monitored days in the Good band, driven mainly by Ozone.
- 35
- median AQI · Good
- 91.0%
- days rated Good
- Ozone
- main pollutant
- 82%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 133.
Annual release change
What changed in the 2025 EPA annual release
- Hancock County's peak single-day AQI rose from 105 to 133 between the 2024 and 2025 EPA annual releases, a change of +28 points.
Data updated August 2026
- Good · 332 d · 91.0%
- Moderate · 29 d · 7.9%
- USG · 4 d · 1.1%
How did Hancock County's air break down in 2025?
Across 365 monitored days, 332 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 133 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 35 (Good).
Insights: Hancock County, Maine. EPA monitors recorded a median Air Quality Index of 35 across 365 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 332 (91%) fell in the Good band (AQI 0–50), 29 (8%) registered Moderate readings, and 4 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 49, while the worst single-day peak hit 133 (USG). Residents averaged about 27.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (333 days), PM2.5 (32 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -0.8 points and the median AQI moved -1 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 133, usg but never Unhealthy. Nearby counties show comparable readings: Androscoggin (85.2% good, AQI 34); Aroostook (83.3% good, AQI 32); Cumberland (74.3% good, AQI 39); Kennebec (85.2% good, AQI 34); Knox (97.8% good, AQI 33); Oxford (75.9% good, AQI 38).
Air Quality Summary
Good Days
91.0%
332 of 365 monitored days
16.0pp vs 75% target
Max AQI Recorded
133
USG
Health Grade
Excellent
90th-pct AQI 49
Hancock County, Good days share 91.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Hancock 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 365 monitored days across EPA AQI categories.
Good
332
91%
Moderate
29
8%
USG
4
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 Hancock County.
- Ozone · 333 days · 91.2%
- PM2.5 · 32 days · 8.8%
Health Impact Assessment
Excellent
Hancock County's air quality is rated Excellent based on 91.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 91.0% of monitored days in 2025, with a median AQI of 35. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 333 of 365 monitored days.
5-Year Air Quality Trend
Air quality is stable in Hancock County. Highest Good-day share: 2020 (91.8%, 336 of 366 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 336 | 29 | 1 | 0 | 36 | 105 |
| 2021 | 324 | 38 | 3 | 0 | 36 | 133 |
| 2022 | 326 | 34 | 1 | 0 | 36 | 112 |
| 2023 | 314 | 51 | 0 | 0 | 38 | 93 |
| 2024 | 334 | 31 | 1 | 0 | 37 | 105 |
| 2025 | 332 | 29 | 4 | 0 | 35 | 133 |
How does Hancock County compare?
How Hancock County compares
Good-day share better than typical
Hancock County 91.0%
Atascosa County, Texas 76.0%
Typical US county 76.0%
Median AQI better than typical
Hancock County 35
Atascosa County, Texas 35
Typical US county 39
Unhealthy days / yr better than typical
Hancock County 0
Atascosa County, Texas 0
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Hancock County (35), not geographic neighbors.
Atascosa County, Texas
Median AQI 35 · 76.0% Good-day share
Benzie County, Michigan
Median AQI 35 · 91.1% Good-day share
Berkeley County, South Carolina
Median AQI 35 · 93.3% Good-day share
Boone County, Indiana
Median AQI 35 · 89.7% Good-day share
Brazoria County, Texas
Median AQI 35 · 80.8% Good-day share
Caroline County, Virginia
Median AQI 35 · 96.7% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Manatee County, Florida
91.0% Good-day share · median AQI 36
Union County, North Carolina
91.0% Good-day share · median AQI 40
Carroll County, Indiana
90.8% Good-day share · median AQI 35
Jefferson County, Tennessee
90.7% Good-day share · median AQI 41
Brevard County, Florida
91.2% Good-day share · median AQI 38
Mayes County, Oklahoma
91.2% Good-day share · median AQI 37
Maine counties on the map
Geographic containment only, other monitored counties in Maine, independent of AQI or pollutant match.
What Hancock 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 35 means for exposure. Health guidance
- See how Hancock County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Hancock County with its Maine neighbours before drawing a conclusion about the region. All of Maine
Based on 365 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Hancock County, Maine? ▼
Hancock County has a median Air Quality Index (AQI) of 35, rated "Good." 91.0% of monitored days (332 out of 365) had good air quality in 2025.
What is the main pollutant in Hancock County? ▼
The primary pollutant in Hancock County is Ozone (O3), which was the main AQI driver on 333 days (91% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Hancock County have? ▼
In 2025, Hancock County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 133.
Is the air quality in Hancock County getting better or worse? ▼
Air quality in Hancock County is stable across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 91.8% (336 of 366 days). Lowest qualifying Good-day share: 2023 at 86.0% (314 of 365 days).
What does AQI 35 mean for health? ▼
Hancock County's median AQI of 35 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Hancock County compare to other counties in Maine? ▼
Hancock County has 91.0% good air days. Nearby counties in Maine: Androscoggin (85.2% good), Aroostook (83.3% good), Cumberland (74.3% good), Kennebec (85.2% good), Knox (97.8% good), Oxford (75.9% good).
What is the 90th percentile AQI in Hancock County? ▼
The 90th percentile AQI for Hancock County is 49, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 133 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Hancock County, Maine · 2020–2025
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Every figure on PlainAirData 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.