Median AQI
41
Good
Michigan · County air quality · 2025
Oakland County, Michigan
Median AQI 41 (Good). 75.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 41
- Median AQI
- 75.0%
- Good-air days
- 1
- Unhealthy days
- 41%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Oakland County's air is good on balance, more polluted than the median US county, a median AQI of 41 with 75.0% of 304 monitored days in the Good band, driven mainly by Ozone.
- 41
- median AQI · Good
- 75.0%
- days rated Good
- Ozone
- main pollutant
- 41%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 166.
Data updated July 2026
- Good · 228 d · 75.0%
- Moderate · 70 d · 23.0%
- USG · 5 d · 1.6%
- Unhealthy · 1 d · 0.3%
How did Oakland County's air break down in 2025?
Across 304 monitored days, 228 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 166 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 304 days monitored. Median AQI: 41 (Good).
Insights: Oakland County, Michigan. EPA monitors recorded a median Air Quality Index of 41 across 304 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 228 (75%) fell in the Good band (AQI 0–50), 70 (23%) registered Moderate readings, and 5 (2%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 66, while the worst single-day peak hit 166 (Unhealthy). Residents averaged about 22.5 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (209 days), PM2.5 (95 days). Across the 2020–2025 trend window, good days shifted by -16 and the median AQI moved +4 points, placing the multi-year trajectory at worsening. Residents and visitors experienced 1 unhealthy-or-worse days combined, periods when the EPA recommends sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Allegan (71.2% good, AQI 43); Bay (71.8% good, AQI 38); Benzie (91.1% good, AQI 35); Berrien (80.9% good, AQI 41); Cass (85.3% good, AQI 40); Clinton (90.2% good, AQI 39).
Air Quality Summary
Good Days
75.0%
228 of 304 monitored days
0.0pp vs 75% target
Max AQI Recorded
166
Unhealthy
Health Grade
Good
90th-pct AQI 66
Oakland County, Good days share 75.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Oakland County, Unhealthy-or-worse share 0.3%
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 304 monitored days across EPA AQI categories.
Good
228
75%
Moderate
70
23%
USG
5
2%
Unhealthy
1
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Oakland County.
- Ozone · 209 days · 68.8%
- PM2.5 · 95 days · 31.3%
Health Impact Assessment
Good
Oakland County's air quality is rated Good based on 75.0% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 5 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 166. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is Ozone, driving AQI on 209 of 304 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Oakland County. Best year: 2020 (244 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 244 | 48 | 6 | 0 | 37 | 126 |
| 2021 | 227 | 68 | 1 | 0 | 39 | 101 |
| 2022 | 236 | 46 | 0 | 0 | 39 | 100 |
| 2023 | 193 | 58 | 9 | 1 | 41 | 169 |
| 2024 | 181 | 119 | 1 | 0 | 45 | 101 |
| 2025 | 228 | 70 | 5 | 1 | 41 | 166 |
How does Oakland County compare?
How Oakland County compares
Good-day share worse than US avg
Oakland County 75.0%
Allegan County, Michigan 71.2%
US average 76.5%
Median AQI worse than US avg
Oakland County 41
Allegan County, Michigan 43
US average 38
Unhealthy days / yr worse than US avg
Oakland County 1
Allegan County, Michigan 1
US average 0
Other Counties in Michigan
Air quality comparison for nearby counties in Michigan.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Oakland 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 Oakland County's air means for you
On most days the air here is fine, but Ozone drives 1 unhealthy-or-worse day 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 Oakland County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Oakland County with its Michigan neighbours before drawing a conclusion about the region. All of Michigan
Based on 304 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 Oakland County, Michigan? ▼
Oakland County has a median Air Quality Index (AQI) of 41, rated "Good." 75.0% of monitored days (228 out of 304) had good air quality in 2025.
What is the main pollutant in Oakland County? ▼
The primary pollutant in Oakland County is Ozone (O3), which was the main AQI driver on 209 days (69% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Oakland County have? ▼
In 2025, Oakland County recorded 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 166.
Is the air quality in Oakland County getting better or worse? ▼
Air quality in Oakland County is worsening based on 5-year trends (2020-2025). Best year: 2020 with 244 good days. Worst year: 2024 with 181 good days.
What does AQI 41 mean for health? ▼
Oakland 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 Oakland County compare to other counties in Michigan? ▼
Oakland County has 75.0% good air days. Nearby counties in Michigan: Allegan (71.2% good), Bay (71.8% good), Benzie (91.1% good), Berrien (80.9% good), Cass (85.3% good), Clinton (90.2% good).
What is the 90th percentile AQI in Oakland County? ▼
The 90th percentile AQI for Oakland County is 66, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 166 (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.