Median AQI
37
Good
Michigan · County air quality · 2025
Ingham County, Michigan
Median AQI 37 (Good). 82.9% of monitored days rated Good, direct from EPA Air Quality System stations.
- 37
- Median AQI
- 82.9%
- Good-air days
- 0
- Unhealthy days
- 60%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Ingham County's air is good on balance, cleaner than the median US county, a median AQI of 37 with 82.9% of 304 monitored days in the Good band, driven mainly by Ozone.
- 37
- median AQI · Good
- 82.9%
- days rated Good
- Ozone
- main pollutant
- 60%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 123.
Data updated July 2026
- Good · 252 d · 82.9%
- Moderate · 49 d · 16.1%
- USG · 3 d · 1.0%
How did Ingham County's air break down in 2025?
Across 304 monitored days, 252 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 123 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 304 days monitored. Median AQI: 37 (Good).
Insights: Ingham County, Michigan. EPA monitors recorded a median Air Quality Index of 37 across 304 measured days in 2025, earning a Good classification and a Good health grade. Of those days, 252 (83%) fell in the Good band (AQI 0–50), 49 (16%) registered Moderate readings, and 3 (1%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 56, while the worst single-day peak hit 123 (USG). Residents averaged about 24.9 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (223 days), PM2.5 (78 days), PM10 (2 days), NO2 (1 days). Across the 2020–2025 trend window, good days shifted by -44 and the median AQI moved +0 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 123, usg but never Unhealthy. 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
82.9%
252 of 304 monitored days
7.9pp vs 75% target
Max AQI Recorded
123
USG
Health Grade
Good
90th-pct AQI 56
Ingham County, Good days share 82.9%
National avg
Share of monitored days at AQI 0-50 (Good band).
Ingham 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 304 monitored days across EPA AQI categories.
Good
252
83%
Moderate
49
16%
USG
3
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 Ingham County.
- Ozone · 223 days · 73.4%
- PM2.5 · 78 days · 25.7%
- PM10 · 2 days · 0.7%
- NO₂ · 1 days · 0.3%
Health Impact Assessment
Good
Ingham County's air quality is rated Good based on 82.9% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 82.9% of monitored days in 2025, with a median AQI of 37. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 223 of 304 monitored days.
5-Year Air Quality Trend
Air quality is stable in Ingham County. Best year: 2020 (296 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 296 | 69 | 0 | 1 | 37 | 151 |
| 2021 | 204 | 159 | 0 | 0 | 46 | 97 |
| 2022 | 236 | 124 | 0 | 0 | 43 | 93 |
| 2023 | 229 | 123 | 7 | 4 | 43 | 194 |
| 2024 | 281 | 85 | 0 | 0 | 39 | 85 |
| 2025 | 252 | 49 | 3 | 0 | 37 | 123 |
How does Ingham County compare?
How Ingham County compares
Good-day share better than US avg
Ingham County 82.9%
Allegan County, Michigan 71.2%
US average 76.5%
Median AQI better than US avg
Ingham County 37
Allegan County, Michigan 43
US average 38
Unhealthy days / yr about average
Ingham County 0
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 Ingham County.
Alachua County, Florida
AQI 37 · 90.1% good
Beltrami County, Minnesota
AQI 37 · 88.8% good
Benewah County, Idaho
AQI 37 · 74.6% good
Brevard County, Florida
AQI 37 · 89.7% good
Brown County, Indiana
AQI 37 · 94.5% good
Brown County, Wisconsin
AQI 37 · 79.0% good
What Ingham 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 37 means for exposure. Health guidance
- See how Ingham County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Ingham 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 Ingham County, Michigan? ▼
Ingham County has a median Air Quality Index (AQI) of 37, rated "Good." 82.9% of monitored days (252 out of 304) had good air quality in 2025.
What is the main pollutant in Ingham County? ▼
The primary pollutant in Ingham County is Ozone (O3), which was the main AQI driver on 223 days (73% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Ingham County have? ▼
In 2025, Ingham County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 123.
Is the air quality in Ingham County getting better or worse? ▼
Air quality in Ingham County is stable based on 5-year trends (2020-2025). Best year: 2020 with 296 good days. Worst year: 2021 with 204 good days.
What does AQI 37 mean for health? ▼
Ingham County's median AQI of 37 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 Ingham County compare to other counties in Michigan? ▼
Ingham County has 82.9% 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 Ingham County? ▼
The 90th percentile AQI for Ingham County is 56, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 123 (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.