Median AQI
18
Good
Michigan · County air quality · 2024
Monroe County, Michigan
Limited EPA sample: 59 monitored days, below the 100-day floor for a full-year verdict. The figures below describe only those reported days.
- 18
- Sample median AQI
- 94.9%
- Good in sample
- 0
- Unhealthy in sample
- 59
- 100-day comparison floor
Monroe County has only 59 EPA-monitored days in 2024, below the 100-day annual floor
According to the U.S. EPA Air Quality System, Monroe County, Michigan reported 59 monitored days in 2024. That sample is too thin for a full-year air-quality grade or peer ranking. Use the figures only as the reported-day record, and check AirNow for current conditions.
Data source EPA Air Quality System (AQS)
- Monitored days
- Monroe County reported 59 monitored days in 2024, below the 100-day floor: sample-only, not a full-year peer rank.
- Sample median AQI
- Sample median AQI: 18
- Annual floor
- Annual floor: 100
The verdict
EPA monitors reported 59 days for Monroe County in 2024, below our 100-day floor for an annual verdict or national comparison. The median AQI of 18 and 94.9% Good-day share describe only those reported days, not the full year.
- 18
- sample median AQI · Good
- 94.9%
- reported days rated Good
- 59 days
- below 100-day floor
No full-year or health conclusion is drawn from this limited reporting window. For current conditions, check EPA AirNow.
Data updated August 2026
- Good · 56 d · 94.9%
- Moderate · 3 d · 5.1%
How did Monroe County's reported sample break down in 2024?
Across 59 monitored days, 56 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 77 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2024). 59 days monitored. Median AQI: 18 (Good).
Limited sample: Monroe County, Michigan. EPA monitors reported 59 days in 2024, short of the 100-day minimum used here for annual verdicts, health grades, rankings, and peer comparisons. Within those reported days, the median was AQI 18, 56 days (95%) were Good, 3 were Moderate, and 0 were Unhealthy for Sensitive Groups. Those figures are observations from the sample, not estimates for unreported days.
The sample's pollutant mix was PM10 (59 days). A gap in reporting can miss seasonal ozone, smoke, or inversion events, so a clean or unhealthy-looking short window must not be generalized to the year. This page therefore withholds a county health grade and national placement. Use the floor-qualifying years in the trend table for historical context and EPA AirNow for current conditions.
Air Quality Summary
Good Days
94.9%
56 of 59 monitored days
19.9pp vs 75% target
Max AQI Recorded
77
Moderate
Coverage Status
Limited sample
59 of 100 required days
AQI Day Breakdown (2024)
Distribution of 59 monitored days across EPA AQI categories.
Good
56
95%
Moderate
3
5%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Monroe County.
- PM10 · 59 days · 100.0%
Sample Coverage and Health Context
Limited sample
Monroe County has no annual health grade because only 59 days were reported, below the 100-day floor. The 94.9% Good-day share describes only that sample.
Reported days do not reveal what happened during unmonitored parts of the year, including seasonal smoke, ozone, or inversion periods. Use these values as a description of the available EPA sample only, and check AirNow.gov for current health guidance.
The dominant pollutant is PM10, driving AQI on 59 of 59 monitored days.
5-Year Air Quality Trend
Air quality is being tracked in Monroe County. The 2024 row is shown for transparency but excluded from the direction because it has fewer than 100 monitored days.
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 58 | 3 | 0 | 0 | 17 | 66 |
| 2021 | 57 | 4 | 0 | 0 | 19 | 77 |
| 2022 | 51 | 8 | 1 | 0 | 26 | 607 |
| 2023 | 59 | 6 | 0 | 0 | 25 | 82 |
| 2024 | 56 | 3 | 0 | 0 | 18 | 77 |
Michigan counties on the map
State neighbors are listed for navigation; Monroe County's limited sample is not scored against them.
What Monroe County's air means for you
Only 59 days were reported in 2024. That is too little evidence for a year-round air-quality or health conclusion.
- Treat the median AQI and Good-day share as observations from the reported sample, not as estimates for unmonitored days. How coverage works
- Use EPA AirNow for current readings and health alerts; this page contains historical annual-summary data. Current conditions
- Browse Michigan counties with fuller monitoring records before drawing a regional comparison. All of Michigan
Limited coverage: 59 EPA-monitored days in 2024, below the 100-day floor for annual claims and comparisons. No values are imputed for missing days.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Monroe County, Michigan? ▼
EPA monitors reported only 59 days for Monroe County in 2024, below the 100-day floor used for annual conclusions. Within that limited sample, the median AQI was 18 and 56 days were rated Good; this does not describe the full year.
What is the main pollutant in Monroe County? ▼
The primary pollutant in Monroe County is Coarse Particles (PM10), which was the main AQI driver on 59 days (100% of monitored days). Irritates airways and can aggravate asthma and bronchitis.
How many unhealthy air days does Monroe County have? ▼
Among 59 reported days in 2024, 0 reached Unhealthy or worse. Because the record is below 100 monitored days, that count cannot establish how many unhealthy days occurred across the full year.
Is the air quality in Monroe County getting better or worse? ▼
Insufficient trend data is available for Monroe County.
What does AQI 18 mean for health? ▼
The median of the 59 reported days was AQI 18, in the "Good" category. The limited sample is not enough to assign the county a full-year health grade. See the AQI category guide for day-level meaning and EPA AirNow for current conditions.
How does Monroe County compare to other counties in Michigan? ▼
Monroe County is not placed in county comparisons because its 59-day record is below the 100-day comparison floor.
What is the 90th percentile AQI in Monroe County? ▼
The 90th percentile AQI for Monroe County is 41, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 77 (Moderate).
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 Monroe 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.