Median AQI
41
Good
New York · County air quality · 2025
Suffolk County, New York
Median AQI 41 (Good). 74.4% of monitored days rated Good, direct from EPA Air Quality System stations.
- 41
- Median AQI
- 74.4%
- Good-air days
- 2
- Unhealthy days
- 40%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Suffolk County's air is good on balance, more polluted than the median US county, a median AQI of 41 with 74.4% of 316 monitored days in the Good band, driven mainly by Ozone.
- 41
- median AQI · Good
- 74.4%
- days rated Good
- Ozone
- main pollutant
- 40%
- cleaner than US counties
2 days reached Unhealthy or worse; the worst single reading hit AQI 154.
Data updated July 2026
- Good · 235 d · 74.4%
- Moderate · 76 d · 24.1%
- USG · 3 d · 0.9%
- Unhealthy · 2 d · 0.6%
How did Suffolk County's air break down in 2025?
Across 316 monitored days, 235 fell in the Good band (AQI 0–50) and 2 reached Unhealthy or worse. The worst single day peaked at AQI 154 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 316 days monitored. Median AQI: 41 (Good).
Insights: Suffolk County, New York. EPA monitors recorded a median Air Quality Index of 41 across 316 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 235 (74%) fell in the Good band (AQI 0–50), 76 (24%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 64, while the worst single-day peak hit 154 (Unhealthy). Residents averaged about 22.3 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (203 days), PM2.5 (113 days). Across the 2020–2025 trend window, good days shifted by -47 and the median AQI moved +1 points, placing the multi-year trajectory at stable. Residents and visitors experienced 2 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. 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
74.4%
235 of 316 monitored days
-0.6pp vs 75% target
Max AQI Recorded
154
Unhealthy
Health Grade
Moderate
90th-pct AQI 64
Suffolk County, Good days share 74.4%
National avg
Share of monitored days at AQI 0-50 (Good band).
Suffolk County, Unhealthy-or-worse share 0.6%
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 316 monitored days across EPA AQI categories.
Good
235
74%
Moderate
76
24%
USG
3
1%
Unhealthy
2
1%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Suffolk County.
- Ozone · 203 days · 64.2%
- PM2.5 · 113 days · 35.8%
Health Impact Assessment
Moderate
Suffolk County's air quality is rated Moderate based on 74.4% good air days. There were 2 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 3 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 154. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is Ozone, driving AQI on 203 of 316 monitored days.
5-Year Air Quality Trend
Air quality is stable in Suffolk County. Best year: 2024 (291 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 282 | 78 | 6 | 0 | 40 | 133 |
| 2021 | 281 | 73 | 10 | 1 | 42 | 154 |
| 2022 | 272 | 85 | 8 | 0 | 42 | 133 |
| 2023 | 278 | 74 | 11 | 2 | 41 | 195 |
| 2024 | 291 | 69 | 6 | 0 | 38 | 133 |
| 2025 | 235 | 76 | 3 | 2 | 41 | 154 |
How does Suffolk County compare?
How Suffolk County compares
Good-day share worse than US avg
Suffolk County 74.4%
Albany County, New York 67.4%
US average 76.5%
Median AQI worse than US avg
Suffolk County 41
Albany County, New York 39
US average 38
Unhealthy days / yr worse than US avg
Suffolk County 2
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 Suffolk County.
Albemarle County, Virginia
AQI 41 · 77.9% good
Anderson County, South Carolina
AQI 41 · 90.0% good
Berkshire County, Massachusetts
AQI 41 · 71.6% good
Berrien County, Michigan
AQI 41 · 80.9% good
Blair County, Pennsylvania
AQI 41 · 71.9% good
Bonner County, Idaho
AQI 41 · 71.3% good
What Suffolk County's air means for you
On most days the air here is fine, but Ozone drives 2 unhealthy-or-worse days a year that sensitive groups should plan around.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 41 means for exposure. Health guidance
- See how Suffolk County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Suffolk County with its New York neighbours before drawing a conclusion about the region. All of New York
Based on 316 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 Suffolk County, New York? ▼
Suffolk County has a median Air Quality Index (AQI) of 41, rated "Good." 74.4% of monitored days (235 out of 316) had good air quality in 2025.
What is the main pollutant in Suffolk County? ▼
The primary pollutant in Suffolk County is Ozone (O3), which was the main AQI driver on 203 days (64% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Suffolk County have? ▼
In 2025, Suffolk County recorded 2 unhealthy air days (2 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 154.
Is the air quality in Suffolk County getting better or worse? ▼
Air quality in Suffolk County is stable based on 5-year trends (2020-2025). Best year: 2024 with 291 good days. Worst year: 2025 with 235 good days.
What does AQI 41 mean for health? ▼
Suffolk County's median AQI of 41 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 Suffolk County compare to other counties in New York? ▼
Suffolk County has 74.4% 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 Suffolk County? ▼
The 90th percentile AQI for Suffolk County is 64, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 154 (Unhealthy).
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.