EnviroNearby

Monroe County, Michigan air quality history

Daily Air Quality Index summaries from EPA monitors in Monroe, Michigan, 1987–2024.

66%
Good days in 2016
41
Median daily AQI, 2016
0
Days above 100 in 2016
120
Days with an AQI in 2016 (of 366)

In 2016, EPA reported a daily Air Quality Index (AQI) for Monroe, Michigan on 120 days. 79 of those days (66%) were in the Good range, and the median daily AQI was 41. That median is about the same as the typical monitored county in Michigan (median 41 across 28 counties), and about the same as the typical monitored U.S. county (41). The main pollutant was fine particles (PM2.5) on 120 days. Across the years with fuller monitoring, the share of Good days rose: an average of 53% in 1993–2006 versus 55% in 2011–2016.

EPA did not report an AQI for every day of 2016 here (120 of 366 days). Figures describe monitored days only; seasonal monitoring (for example, ozone measured only in warmer months) can make a county look cleaner or dirtier than a full-year record would.

The most recent year with data for this county is 2024; EPA's files for 2025–2025 contain no row for it, which usually means its monitors stopped reporting.

Years with fewer than 120 monitored days (2019, 2020, 2021, 2022, 2023, 2024…) 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%1987: Good 29 of 31 days1987: Moderate 2 of 31 days19871988: Good 55 of 65 days1988: Moderate 10 of 65 days1989: Good 41 of 47 days1989: Moderate 6 of 47 days1990: Good 34 of 40 days1990: Moderate 6 of 40 days1991: Good 53 of 54 days1991: Moderate 1 of 54 days1992: Good 58 of 59 days1992: Moderate 1 of 59 days19921993: Good 135 of 160 days1993: Moderate 23 of 160 days1993: Unhealthy 1 of 160 days1993: Very Unhealthy 1 of 160 days1994: Good 53 of 55 days1994: Moderate 2 of 55 days1995: Good 59 of 61 days1995: Moderate 2 of 61 days1996: Good 54 of 55 days1996: Moderate 1 of 55 days1997: Good 53 of 54 days1997: Moderate 1 of 54 days19971998: Good 15 of 15 days1999: Moderate 5 of 5 days2000: Good 34 of 117 days2000: Moderate 80 of 117 days2000: Unhealthy for Sensitive Groups 3 of 117 days2001: Good 32 of 111 days2001: Moderate 74 of 111 days2001: Unhealthy for Sensitive Groups 5 of 111 days2002: Good 27 of 114 days2002: Moderate 81 of 114 days2002: Unhealthy for Sensitive Groups 5 of 114 days2002: Unhealthy 1 of 114 days20022003: Good 35 of 119 days2003: Moderate 80 of 119 days2003: Unhealthy for Sensitive Groups 3 of 119 days2003: Unhealthy 1 of 119 days2004: Good 47 of 120 days2004: Moderate 71 of 120 days2004: Unhealthy for Sensitive Groups 2 of 120 days2005: Good 36 of 115 days2005: Moderate 71 of 115 days2005: Unhealthy for Sensitive Groups 6 of 115 days2005: Unhealthy 2 of 115 days2006: Good 41 of 120 days2006: Moderate 77 of 120 days2006: Unhealthy for Sensitive Groups 2 of 120 days2007: Good 37 of 118 days2007: Moderate 78 of 118 days2007: Unhealthy for Sensitive Groups 3 of 118 days20072008: Good 45 of 117 days2008: Moderate 72 of 117 days2009: Good 59 of 120 days2009: Moderate 60 of 120 days2009: Unhealthy for Sensitive Groups 1 of 120 days2010: Good 68 of 123 days2010: Moderate 54 of 123 days2010: Unhealthy for Sensitive Groups 1 of 123 days2011: Good 67 of 127 days2011: Moderate 60 of 127 days2012: Good 59 of 124 days2012: Moderate 64 of 124 days2012: Unhealthy for Sensitive Groups 1 of 124 days20122013: Good 64 of 116 days2013: Moderate 52 of 116 days2014: Good 60 of 116 days2014: Moderate 56 of 116 days2015: Good 69 of 118 days2015: Moderate 48 of 118 days2015: Unhealthy for Sensitive Groups 1 of 118 days2016: Good 79 of 120 days2016: Moderate 41 of 120 days2017: Good 78 of 116 days2017: Moderate 38 of 116 days20172018: Good 60 of 61 days2018: Moderate 1 of 61 days2019: Good 57 of 61 days2019: Moderate 4 of 61 days2020: Good 58 of 61 days2020: Moderate 3 of 61 days2021: Good 57 of 61 days2021: Moderate 4 of 61 days2022: Good 51 of 61 days2022: Moderate 8 of 61 days2022: Unhealthy for Sensitive Groups 1 of 61 days2022: Hazardous 1 of 61 days20222023: Good 59 of 65 days2023: Moderate 6 of 65 days2024: Good 56 of 59 days2024: Moderate 3 of 59 days2024
  • 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 year0501001987: 90th percentile AQI 451988: 90th percentile AQI 551989: 90th percentile AQI 531990: 90th percentile AQI 531991: 90th percentile AQI 441992: 90th percentile AQI 351993: 90th percentile AQI 611994: 90th percentile AQI 431995: 90th percentile AQI 371996: 90th percentile AQI 341997: 90th percentile AQI 291998: 90th percentile AQI 241999: 90th percentile AQI 682000: 90th percentile AQI 852001: 90th percentile AQI 872002: 90th percentile AQI 882003: 90th percentile AQI 852004: 90th percentile AQI 832005: 90th percentile AQI 912006: 90th percentile AQI 792007: 90th percentile AQI 782008: 90th percentile AQI 752009: 90th percentile AQI 702010: 90th percentile AQI 692011: 90th percentile AQI 712012: 90th percentile AQI 642013: 90th percentile AQI 622014: 90th percentile AQI 622015: 90th percentile AQI 662016: 90th percentile AQI 582017: 90th percentile AQI 592018: 90th percentile AQI 312019: 90th percentile AQI 462020: 90th percentile AQI 402021: 90th percentile AQI 452022: 90th percentile AQI 592023: 90th percentile AQI 452024: 90th percentile AQI 411987: Median AQI 241988: Median AQI 301989: Median AQI 301990: Median AQI 281991: Median AQI 221992: Median AQI 191993: Median AQI 351994: Median AQI 191995: Median AQI 201996: Median AQI 191997: Median AQI 181998: Median AQI 151999: Median AQI 562000: Median AQI 602001: Median AQI 582002: Median AQI 612003: Median AQI 572004: Median AQI 542005: Median AQI 582006: Median AQI 562007: Median AQI 582008: Median AQI 542009: Median AQI 512010: Median AQI 472011: Median AQI 492012: Median AQI 522013: Median AQI 462014: Median AQI 502015: Median AQI 442016: Median AQI 412017: Median AQI 382018: Median AQI 132019: Median AQI 162020: Median AQI 172021: Median AQI 192022: Median AQI 262023: Median AQI 252024: Median AQI 18198719921997200220072012201720222024
  • Median daily AQI
  • 90th-percentile daily AQI

Main pollutant by day, 2016

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)120100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2024595630000184177PM10
2023655960000254582PM10
20226151810012659607PM10
2021615740000194577PM10
2020615830000174066PM10
2019615740000164676PM10
2018616010000133159PM10
201711678380000385988PM2.5
201612079410000415872PM2.5
2015118694810004466101PM2.5
201411660560000506295PM2.5
201311664520000466273PM2.5
2012124596410005264105PM2.5
201112767600000497182PM2.5
2010123685410004769117PM2.5
2009120596010005170103PM2.5
200811745720000547599PM2.5
2007118377830005878112PM2.5
2006120417720005679115PM2.5
2005115367162005891163PM2.5
2004120477120005483109PM2.5
2003119358031005785157PM2.5
2002114278151006188156PM2.5
2001111327450005887132PM2.5
2000117348030006085112PM2.5
19995050000566868PM2.5
1998151500000152428PM10
1997545310000182951PM10
1996555410000193451PM10
1995615920000203754PM10
1994555320000194376PM10
19931601352301103561201Ozone
1992595810000193559PM10
1991545310000224452PM10
1990403460000285361PM10
1989474160000305362PM10
19886555100000305565PM10
1987312920000244570PM10

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.

All monitored counties in Michigan

Source: U.S. EPA AirData, “Annual AQI by County” files for 1987–2024 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem