EnviroNearby

Monroe County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Monroe, Indiana, 2009–2025.

74%
Good days in 2025
36
Median daily AQI, 2025
0
Days above 100 in 2025
360
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Monroe, Indiana on 360 days. 265 of those days (74%) were in the Good range, and the median daily AQI was 36. That median is lower than the typical monitored county in Indiana (median 41 across 33 counties), and lower than the typical monitored U.S. county (40). The main pollutant was fine particles (PM2.5) on 360 days. Across the years with fuller monitoring, the share of Good days rose: an average of 37% in 2009–2011 versus 74% in 2023–2025.

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%2009: Good 74 of 245 days2009: Moderate 171 of 245 days20092010: Good 99 of 302 days2010: Moderate 203 of 302 days2011: Good 152 of 319 days2011: Moderate 167 of 319 days20112012: Good 225 of 356 days2012: Moderate 131 of 356 days2013: Good 207 of 348 days2013: Moderate 141 of 348 days20132014: Good 210 of 346 days2014: Moderate 135 of 346 days2014: Unhealthy 1 of 346 days2015: Good 231 of 342 days2015: Moderate 111 of 342 days20152016: Good 295 of 354 days2016: Moderate 59 of 354 days2017: Good 265 of 341 days2017: Moderate 76 of 341 days20172018: Good 182 of 335 days2018: Moderate 153 of 335 days2019: Good 220 of 346 days2019: Moderate 126 of 346 days20192020: Good 240 of 357 days2020: Moderate 117 of 357 days2021: Good 223 of 352 days2021: Moderate 129 of 352 days20212022: Good 265 of 347 days2022: Moderate 82 of 347 days2023: Good 245 of 365 days2023: Moderate 115 of 365 days2023: Unhealthy for Sensitive Groups 3 of 365 days2023: Unhealthy 1 of 365 days2023: Very Unhealthy 1 of 365 days20232024: Good 290 of 359 days2024: Moderate 69 of 359 days2025: Good 265 of 360 days2025: Moderate 95 of 360 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 year0501002009: 90th percentile AQI 712010: 90th percentile AQI 702011: 90th percentile AQI 702012: 90th percentile AQI 592013: 90th percentile AQI 612014: 90th percentile AQI 622015: 90th percentile AQI 592016: 90th percentile AQI 532017: 90th percentile AQI 552018: 90th percentile AQI 632019: 90th percentile AQI 582020: 90th percentile AQI 572021: 90th percentile AQI 612022: 90th percentile AQI 552023: 90th percentile AQI 612024: 90th percentile AQI 542025: 90th percentile AQI 582009: Median AQI 552010: Median AQI 562011: Median AQI 522012: Median AQI 432013: Median AQI 462014: Median AQI 442015: Median AQI 412016: Median AQI 342017: Median AQI 362018: Median AQI 482019: Median AQI 432020: Median AQI 412021: Median AQI 432022: Median AQI 382023: Median AQI 402024: Median AQI 342025: Median AQI 36200920112013201520172019202120232025
  • 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)360100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025360265950000365884PM2.5
2024359290690000345463PM2.5
202336524511531104061230PM2.5
2022347265820000385596PM2.5
20213522231290000436195PM2.5
20203572401170000415772PM2.5
20193462201260000435872PM2.5
20183351821530000486398PM2.5
2017341265760000365566PM2.5
2016354295590000345366PM2.5
20153422311110000415982PM2.5
201434621013501004462159PM2.5
20133482071410000466178PM2.5
20123562251310000435988PM2.5
20113191521670000527099PM2.5
2010302992030000567089PM2.5
2009245741710000557189PM2.5

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 Indiana with a similar median AQI in 2025

All monitored counties in Indiana

Source: U.S. EPA AirData, “Annual AQI by County” files for 2009–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem