Median AQI
38
Good
Michigan · County air quality · 2025
Ingham County, Michigan
Median AQI 38 (Good). 72.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 38
- Median AQI
- 72.6%
- Good-air days
- 1
- Unhealthy days
- 38%
- Cleaner than US counties
Ingham County's 2025 annual median AQI is 38 (Good), with 72.6% Good days
According to the U.S. EPA Air Quality System, Ingham County, Michigan posted a 2025 median AQI of 38 (Good) across 365 monitored days, with 72.6% rated Good and 1 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Ingham County's 72.6% Good-day share places it cleaner than 38% of US counties in 2025.
- Closest median-AQI peer
- Adams County (94.7% Good, median AQI 38) is the closest nationwide median-AQI peer to Ingham County.
- 2020–2025 trend
- Ingham County's floor-qualifying Good-day share is worsening from 2020 to 2025 (80.9% → 72.6%).
- Median AQI
- Median AQI: 38
The verdict
According to EPA Air Quality System monitoring data, Ingham County's air is good on balance, more polluted than the median US county, a median AQI of 38 with 72.6% of 365 monitored days in the Good band, driven mainly by Ozone.
- 38
- median AQI · Good
- 72.6%
- days rated Good
- Ozone
- main pollutant
- 38%
- cleaner than US counties
1 day reached Unhealthy or worse; the worst single reading hit AQI 153.
Annual release change
What changed in the 2025 EPA annual release
- Ingham County's peak single-day AQI rose from 85 to 153 between the 2024 and 2025 EPA annual releases, a change of +68 points.
- Ingham County's Good-day share fell from 76.8% to 72.6% between the 2024 and 2025 EPA annual releases, a change of -4.2 percentage points.
- Ingham County's Unhealthy-category days rose from 0 to 1 between the 2024 and 2025 EPA annual releases, a change of +1 days.
Data updated August 2026
- Good · 265 d · 72.6%
- Moderate · 92 d · 25.2%
- USG · 7 d · 1.9%
- Unhealthy · 1 d · 0.3%
How did Ingham County's air break down in 2025?
Across 365 monitored days, 265 fell in the Good band (AQI 0–50) and 1 reached Unhealthy or worse. The worst single day peaked at AQI 153 (Unhealthy).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 38 (Good).
Insights: Ingham County, Michigan. EPA monitors recorded a median Air Quality Index of 38 across 365 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 265 (73%) fell in the Good band (AQI 0–50), 92 (25%) registered Moderate readings, and 7 (2%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 62, while the worst single-day peak hit 153 (Unhealthy). Residents averaged about 21.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (194 days), PM2.5 (166 days), NO2 (3 days), PM10 (2 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -8.3 points and the median AQI moved +1 points, placing the multi-year trajectory at worsening. The annual record contains 1 day at Unhealthy or worse. On that day, the EPA recommends that sensitive groups limit prolonged outdoor exertion. Nearby counties show comparable readings: Allegan (63.9% good, AQI 44); Bay (70.4% good, AQI 39); 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
72.6%
265 of 365 monitored days
-2.4pp vs 75% target
Max AQI Recorded
153
Unhealthy
Health Grade
Moderate
90th-pct AQI 62
Ingham County, Good days share 72.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Ingham County, Unhealthy-or-worse share 2.7%
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 365 monitored days across EPA AQI categories.
Good
265
73%
Moderate
92
25%
USG
7
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 Ingham County.
- Ozone · 194 days · 53.2%
- PM2.5 · 166 days · 45.5%
- NO₂ · 3 days · 0.8%
- PM10 · 2 days · 0.5%
Health Impact Assessment
Moderate
Ingham County's air quality is rated Moderate based on 72.6% good air days. There were 1 unhealthy days in 2025 when outdoor activity should be limited.
Air quality is acceptable most days, but 7 days reached "Unhealthy for Sensitive Groups" (AQI 101-150) and peak AQI reached 153. Sensitive groups should monitor real-time conditions at AirNow.gov.
The dominant pollutant is Ozone, driving AQI on 194 of 365 monitored days.
5-Year Air Quality Trend
Air quality is worsening in Ingham County. Highest Good-day share: 2020 (80.9%, 296 of 366 monitored 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 | 265 | 92 | 7 | 1 | 38 | 153 |
How does Ingham County compare?
How Ingham County compares
Good-day share worse than US avg
Ingham County 72.6%
Adams County, Illinois 94.7%
US average 76.0%
Median AQI better than US avg
Ingham County 38
Adams County, Illinois 38
US average 39
Unhealthy days / yr about average
Ingham County 1
Adams County, Illinois 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Ingham County (38), not geographic neighbors.
Adams County, Illinois
Median AQI 38 · 94.7% Good-day share
Albemarle County, Virginia
Median AQI 38 · 81.0% Good-day share
Alexander County, North Carolina
Median AQI 38 · 93.5% Good-day share
Amador County, California
Median AQI 38 · 87.4% Good-day share
Anoka County, Minnesota
Median AQI 38 · 74.1% Good-day share
Avery County, North Carolina
Median AQI 38 · 92.3% 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).
Bartholomew County, Indiana
72.6% Good-day share · median AQI 43
Mercer County, Pennsylvania
72.6% Good-day share · median AQI 42
Suffolk County, New York
72.6% Good-day share · median AQI 41
Gunnison County, Colorado
72.5% Good-day share · median AQI 46
Jersey County, Illinois
72.3% Good-day share · median AQI 42
Dodge County, Wisconsin
72.3% Good-day share · median AQI 40
Michigan counties on the map
Geographic containment only, other monitored counties in Michigan, independent of AQI or pollutant match.
What Ingham 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 38 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 365 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 Ingham County, Michigan? ▼
Ingham County has a median Air Quality Index (AQI) of 38, rated "Good." 72.6% of monitored days (265 out of 365) 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 194 days (53% 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 1 unhealthy air days (1 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 153.
Is the air quality in Ingham County getting better or worse? ▼
Air quality in Ingham County is worsening across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2020 at 80.9% (296 of 366 days). Lowest qualifying Good-day share: 2021 at 56.2% (204 of 363 days).
What does AQI 38 mean for health? ▼
Ingham County's median AQI of 38 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Ingham County compare to other counties in Michigan? ▼
Ingham County has 72.6% good air days. Nearby counties in Michigan: Allegan (63.9% good), Bay (70.4% 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 62, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 153 (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. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Ingham County, Michigan · 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.