Median AQI
39
Good
New York · County air quality · 2025
Onondaga County, New York
Median AQI 39 (Good). 79.5% of monitored days rated Good, direct from EPA Air Quality System stations.
- 39
- Median AQI
- 79.5%
- Good-air days
- 0
- Unhealthy days
- 50%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Onondaga County's air is good on balance, cleaner than the median US county, a median AQI of 39 with 79.5% of 273 monitored days in the Good band, driven mainly by Ozone.
- 39
- median AQI · Good
- 79.5%
- days rated Good
- Ozone
- main pollutant
- 50%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 125.
Data updated July 2026
- Good · 217 d · 79.5%
- Moderate · 52 d · 19.0%
- USG · 4 d · 1.5%
How did Onondaga County's air break down in 2025?
Across 273 monitored days, 217 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 125 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 273 days monitored. Median AQI: 39 (Good).
Insights: Onondaga County, New York. EPA monitors recorded a median Air Quality Index of 39 across 273 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 217 (79%) fell in the Good band (AQI 0–50), 52 (19%) registered Moderate readings, and 4 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 58, while the worst single-day peak hit 125 (USG). Residents averaged about 23.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (187 days), PM2.5 (86 days). Across the 2020–2025 trend window, good days shifted by -83 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 125, usg 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
79.5%
217 of 273 monitored days
4.5pp vs 75% target
Max AQI Recorded
125
USG
Health Grade
Good
90th-pct AQI 58
Onondaga County, Good days share 79.5%
National avg
Share of monitored days at AQI 0-50 (Good band).
Onondaga 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 273 monitored days across EPA AQI categories.
Good
217
79%
Moderate
52
19%
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 Onondaga County.
- Ozone · 187 days · 68.5%
- PM2.5 · 86 days · 31.5%
Health Impact Assessment
Good
Onondaga County's air quality is rated Good based on 79.5% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 79.5% 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 Ozone, driving AQI on 187 of 273 monitored days.
5-Year Air Quality Trend
Air quality is stable in Onondaga County. Best year: 2024 (317 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 300 | 64 | 0 | 0 | 37 | 74 |
| 2021 | 279 | 85 | 1 | 0 | 39 | 113 |
| 2022 | 316 | 49 | 0 | 0 | 37 | 69 |
| 2023 | 273 | 80 | 4 | 3 | 40 | 258 |
| 2024 | 317 | 48 | 0 | 0 | 35 | 84 |
| 2025 | 217 | 52 | 4 | 0 | 39 | 125 |
How does Onondaga County compare?
How Onondaga County compares
Good-day share better than US avg
Onondaga County 79.5%
Albany County, New York 67.4%
US average 76.5%
Median AQI worse than US avg
Onondaga County 39
Albany County, New York 39
US average 38
Unhealthy days / yr about average
Onondaga 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 Onondaga 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 Onondaga 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 39 means for exposure. Health guidance
- See how Onondaga County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Onondaga County with its New York neighbours before drawing a conclusion about the region. All of New York
Based on 273 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 Onondaga County, New York? ▼
Onondaga County has a median Air Quality Index (AQI) of 39, rated "Good." 79.5% of monitored days (217 out of 273) had good air quality in 2025.
What is the main pollutant in Onondaga County? ▼
The primary pollutant in Onondaga County is Ozone (O3), which was the main AQI driver on 187 days (68% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Onondaga County have? ▼
In 2025, Onondaga County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 125.
Is the air quality in Onondaga County getting better or worse? ▼
Air quality in Onondaga County is stable based on 5-year trends (2020-2025). Best year: 2024 with 317 good days. Worst year: 2025 with 217 good days.
What does AQI 39 mean for health? ▼
Onondaga 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 Onondaga County compare to other counties in New York? ▼
Onondaga County has 79.5% 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 Onondaga County? ▼
The 90th percentile AQI for Onondaga County is 58, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 125 (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.