Median AQI
36
Good
New York · County air quality · 2025
Hamilton County, New York
Median AQI 36 (Good). 96.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 36
- Median AQI
- 96.6%
- Good-air days
- 0
- Unhealthy days
- 93%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Hamilton County's air is good on balance, among the cleanest 10% of US counties, a median AQI of 36 with 96.6% of 266 monitored days in the Good band, driven mainly by Ozone.
- 36
- median AQI · Good
- 96.6%
- days rated Good
- Ozone
- main pollutant
- 93%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 87.
Data updated July 2026
- Good · 257 d · 96.6%
- Moderate · 9 d · 3.4%
How did Hamilton County's air break down in 2025?
Across 266 monitored days, 257 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 87 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 266 days monitored. Median AQI: 36 (Good).
Insights: Hamilton County, New York. EPA monitors recorded a median Air Quality Index of 36 across 266 measured days in 2025, earning a Good classification and a Excellent health grade. Of those days, 257 (97%) fell in the Good band (AQI 0–50), 9 (3%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 45, while the worst single-day peak hit 87 (Moderate). Residents averaged about 29.0 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (266 days). Across the 2020–2025 trend window, good days shifted by -97 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 87, moderate but never Unhealthy. Nearby counties show comparable readings: Albany (67.4% good, AQI 39); Bronx (56.6% good, AQI 47); Chautauqua (88.6% good, AQI 39); Dutchess (92.7% good, AQI 37); Erie (61.3% good, AQI 44); Essex (79.8% good, AQI 42).
Air Quality Summary
Good Days
96.6%
257 of 266 monitored days
21.6pp vs 75% target
Max AQI Recorded
87
Moderate
Health Grade
Excellent
90th-pct AQI 45
Hamilton County, Good days share 96.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Hamilton 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 266 monitored days across EPA AQI categories.
Good
257
97%
Moderate
9
3%
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 Hamilton County.
- Ozone · 266 days · 100.0%
Health Impact Assessment
Excellent
Hamilton County's air quality is rated Excellent based on 96.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 96.6% of monitored days in 2025, with a median AQI of 36. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 266 of 266 monitored days.
5-Year Air Quality Trend
Air quality is stable in Hamilton County. Best year: 2020 (354 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 354 | 3 | 0 | 0 | 34 | 54 |
| 2021 | 343 | 15 | 0 | 0 | 33 | 100 |
| 2022 | 345 | 5 | 0 | 0 | 34 | 71 |
| 2023 | 337 | 17 | 0 | 0 | 33 | 90 |
| 2024 | 340 | 8 | 0 | 0 | 33 | 74 |
| 2025 | 257 | 9 | 0 | 0 | 36 | 87 |
How does Hamilton County compare?
How Hamilton County compares
Good-day share better than US avg
Hamilton County 96.6%
Albany County, New York 67.4%
US average 76.5%
Median AQI better than US avg
Hamilton County 36
Albany County, New York 39
US average 38
Unhealthy days / yr about average
Hamilton County 0
Albany County, New York 0
US average 0
Other Counties in New York
Air quality comparison for nearby counties in New York.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Hamilton County.
Aroostook County, Maine
AQI 36 · 84.1% good
Berkeley County, South Carolina
AQI 36 · 92.2% good
Carter County, Kentucky
AQI 36 · 89.8% good
Claiborne County, Tennessee
AQI 36 · 96.3% good
Clark County, Illinois
AQI 36 · 92.1% good
Cobb County, Georgia
AQI 36 · 92.5% good
What Hamilton 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 36 means for exposure. Health guidance
- See how Hamilton County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Hamilton County with its New York neighbours before drawing a conclusion about the region. All of New York
Based on 266 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 Hamilton County, New York? ▼
Hamilton County has a median Air Quality Index (AQI) of 36, rated "Good." 96.6% of monitored days (257 out of 266) had good air quality in 2025.
What is the main pollutant in Hamilton County? ▼
The primary pollutant in Hamilton County is Ozone (O3), which was the main AQI driver on 266 days (100% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Hamilton County have? ▼
In 2025, Hamilton County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 87.
Is the air quality in Hamilton County getting better or worse? ▼
Air quality in Hamilton County is stable based on 5-year trends (2020-2025). Best year: 2020 with 354 good days. Worst year: 2025 with 257 good days.
What does AQI 36 mean for health? ▼
Hamilton County's median AQI of 36 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 Hamilton County compare to other counties in New York? ▼
Hamilton County has 96.6% good air days. Nearby counties in New York: Albany (67.4% good), Bronx (56.6% good), Chautauqua (88.6% good), Dutchess (92.7% good), Erie (61.3% good), Essex (79.8% good).
What is the 90th percentile AQI in Hamilton County? ▼
The 90th percentile AQI for Hamilton County is 45, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 87 (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.