EnviroNearby

Marquette County, Michigan air quality history

Daily Air Quality Index summaries from EPA monitors in Marquette, Michigan, 1980–2025.

82%
Good days in 2025
19
Median daily AQI, 2025
13
Days above 100 in 2025
307
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Marquette, Michigan on 307 days. 253 of those days (82%) were in the Good range, and the median daily AQI was 19. That median is lower than the typical monitored county in Michigan (median 39 across 26 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 307 days.

Years with fewer than 120 monitored days (1992, 1994, 1995, 1996, 1997, 1998…) are shown in the table but left out of comparisons and trend statements.

How the days broke down each year

Each bar is one year. The colored segments show the share of monitored days that fell in each AQI category.

Share of monitored days in each AQI category, by year0%25%50%75%100%1980: Good 302 of 333 days1980: Moderate 18 of 333 days1980: Unhealthy for Sensitive Groups 11 of 333 days1980: Unhealthy 2 of 333 days19801981: Good 258 of 279 days1981: Moderate 17 of 279 days1981: Unhealthy for Sensitive Groups 4 of 279 days19811989: Good 55 of 60 days1989: Moderate 5 of 60 days19891990: Good 58 of 61 days1990: Moderate 3 of 61 days19901991: Good 58 of 60 days1991: Moderate 2 of 60 days19911992: Good 61 of 61 days19921993: Good 187 of 190 days1993: Moderate 3 of 190 days19931994: Good 61 of 61 days19941995: Good 57 of 58 days1995: Moderate 1 of 58 days19951996: Good 54 of 61 days1996: Moderate 7 of 61 days19961997: Good 60 of 61 days1997: Moderate 1 of 61 days19971998: Good 5 of 5 days19982024: Good 202 of 224 days2024: Moderate 22 of 224 days20242025: Good 253 of 307 days2025: Moderate 41 of 307 days2025: Unhealthy for Sensitive Groups 7 of 307 days2025: Unhealthy 6 of 307 days2025
  • Good
  • Moderate
  • Unhealthy for Sensitive Groups
  • Unhealthy
  • Very Unhealthy
  • Hazardous

Typical and high-end AQI over time

The median is the middle day of the year. The 90th percentile is the level that only the highest 10% of days exceeded.

Median and 90th-percentile daily AQI, by year0501001980: 90th percentile AQI 501981: 90th percentile AQI 491989: 90th percentile AQI 501990: 90th percentile AQI 351991: 90th percentile AQI 291992: 90th percentile AQI 271993: 90th percentile AQI 361994: 90th percentile AQI 291995: 90th percentile AQI 261996: 90th percentile AQI 521997: 90th percentile AQI 311998: 90th percentile AQI 172024: 90th percentile AQI 482025: 90th percentile AQI 621980: Median AQI 361981: Median AQI 341989: Median AQI 181990: Median AQI 131991: Median AQI 121992: Median AQI 91993: Median AQI 261994: Median AQI 111995: Median AQI 101996: Median AQI 151997: Median AQI 101998: Median AQI 62024: Median AQI 192025: Median AQI 1919801981198919901991199219931994199519961997199820242025
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2025

On each monitored day, the AQI reflects whichever measured pollutant had the highest index. This counts how many days each pollutant set the AQI. A pollutant that was not measured here cannot appear.

PollutantDays as main pollutantShare of monitored days
Fine particles (PM2.5)307100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253072534176001962193PM2.5
2024224202220000194867PM2.5
1998550000061717PM10
1997616010000103151PM10
1996615470000155286PM10
1995585710000102660PM10
1994616100000112944PM10
199319018730000263677Ozone
199261610000092749PM10
1991605820000122990PM10
1990615830000133562PM10
1989605550000185055PM10
19812792581740003449147Ozone
198033330218112003650169Ozone

What this data can and can’t tell you

It is a county-level summary. EPA reports one AQI per day for the county, based on the monitors operating there. Air at a particular street, school or home can differ, especially near roads, industry or wildfire smoke.

It is not a health assessment. The AQI is EPA’s scale for communicating daily air quality. A county’s history can’t tell you what the health risk is for any particular person. For daily conditions and health guidance, see AirNow.

Rules change over time. EPA has revised AQI breakpoints, most recently for fine particles in 2024, so some year-to-year change can reflect the scale rather than the air.

Counties in Michigan with a similar median AQI in 2025

All monitored counties in Michigan

Source: U.S. EPA AirData, “Annual AQI by County” files for 1980–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem