Median AQI
36
Good
New York · County air quality · 2025
Onondaga County, New York
Median AQI 36 (Good). 83.2% of monitored days rated Good, direct from EPA Air Quality System stations.
- 36
- Median AQI
- 83.2%
- Good-air days
- 0
- Unhealthy days
- 64%
- Cleaner than US counties
Onondaga County's 2025 annual median AQI is 36 (Good), with 83.2% Good days
According to the U.S. EPA Air Quality System, Onondaga County, New York posted a 2025 median AQI of 36 (Good) across 358 monitored days, with 83.2% 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
- Onondaga County's 83.2% Good-day share places it cleaner than 64% of US counties in 2025.
- Closest median-AQI peer
- Ashland County (81.6% Good, median AQI 36) is the closest nationwide median-AQI peer to Onondaga County.
- 2020–2025 trend
- Onondaga County's floor-qualifying Good-day share is stable from 2020 to 2025 (82.4% → 83.2%).
- Median AQI
- Median AQI: 36
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 36 with 83.2% of 358 monitored days in the Good band, driven mainly by Ozone.
- 36
- median AQI · Good
- 83.2%
- days rated Good
- Ozone
- main pollutant
- 64%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 125.
Annual release change
What changed in the 2025 EPA annual release
- Onondaga County's peak single-day AQI rose from 84 to 125 between the 2024 and 2025 EPA annual releases, a change of +41 points.
- Onondaga County's Good-day share fell from 86.8% to 83.2% between the 2024 and 2025 EPA annual releases, a change of -3.6 percentage points.
Data updated August 2026
- Good · 298 d · 83.2%
- Moderate · 56 d · 15.6%
- USG · 4 d · 1.1%
How did Onondaga County's air break down in 2025?
Across 358 monitored days, 298 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). 358 days monitored. Median AQI: 36 (Good).
Insights: Onondaga County, New York. EPA monitors recorded a median Air Quality Index of 36 across 358 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 298 (83%) fell in the Good band (AQI 0–50), 56 (16%) registered Moderate readings, and 4 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 57, while the worst single-day peak hit 125 (USG). Residents averaged about 25.0 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (249 days), PM2.5 (109 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 125, usg but never Unhealthy. Nearby counties show comparable readings: Albany (68.5% good, AQI 39); Bronx (59.2% good, AQI 45); Chautauqua (89.0% good, AQI 36); Dutchess (94.0% good, AQI 34); Erie (63.8% good, AQI 44); Essex (83.8% good, AQI 41).
Air Quality Summary
Good Days
83.2%
298 of 358 monitored days
8.2pp vs 75% target
Max AQI Recorded
125
USG
Health Grade
Good
90th-pct AQI 57
Onondaga County, Good days share 83.2%
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 358 monitored days across EPA AQI categories.
Good
298
83%
Moderate
56
16%
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 · 249 days · 69.6%
- PM2.5 · 109 days · 30.4%
Health Impact Assessment
Good
Onondaga County's air quality is rated Good based on 83.2% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 83.2% 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 249 of 358 monitored days.
5-Year Air Quality Trend
Air quality is stable in Onondaga County. Highest Good-day share: 2024 (86.8%, 317 of 365 monitored 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 | 298 | 56 | 4 | 0 | 36 | 125 |
How does Onondaga County compare?
How Onondaga County compares
Good-day share better than typical
Onondaga County 83.2%
Ashland County, Wisconsin 81.6%
Typical US county 76.0%
Median AQI better than typical
Onondaga County 36
Ashland County, Wisconsin 36
Typical US county 39
Unhealthy days / yr better than typical
Onondaga County 0
Ashland County, Wisconsin 8
Typical US county 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Onondaga County (36), not geographic neighbors.
Ashland County, Wisconsin
Median AQI 36 · 81.6% Good-day share
Atlantic County, New Jersey
Median AQI 36 · 82.2% Good-day share
Bannock County, Idaho
Median AQI 36 · 88.8% Good-day share
Barnstable County, Massachusetts
Median AQI 36 · 93.7% Good-day share
Beltrami County, Minnesota
Median AQI 36 · 79.1% Good-day share
Benton County, Washington
Median AQI 36 · 80.3% 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).
Steuben County, New York
83.3% Good-day share · median AQI 38
Washington County, Arkansas
83.3% Good-day share · median AQI 40
Genesee County, Michigan
83.2% Good-day share · median AQI 38
Clinton County, Ohio
83.1% Good-day share · median AQI 41
Hood County, Texas
83.4% Good-day share · median AQI 38
Montgomery County, Maryland
83.1% Good-day share · median AQI 39
New York counties on the map
Geographic containment only, other monitored counties in New York, independent of AQI or pollutant match.
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 36 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 358 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 Onondaga County, New York? ▼
Onondaga County has a median Air Quality Index (AQI) of 36, rated "Good." 83.2% of monitored days (298 out of 358) 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 249 days (70% 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 across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2024 at 86.8% (317 of 365 days). Lowest qualifying Good-day share: 2023 at 75.8% (273 of 361 days).
What does AQI 36 mean for health? ▼
Onondaga County's median AQI of 36 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Onondaga County compare to other counties in New York? ▼
Onondaga County has 83.2% good air days. Nearby counties in New York: Albany (68.5% good), Bronx (59.2% good), Chautauqua (89.0% good), Dutchess (94.0% good), Erie (63.8% good), Essex (83.8% good).
What is the 90th percentile AQI in Onondaga County? ▼
The 90th percentile AQI for Onondaga County is 57, 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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Onondaga County, New York · 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.