EnviroNearby

Bartholomew County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Bartholomew, Indiana, 1989–2025.

73%
Good days in 2025
43
Median daily AQI, 2025
0
Days above 100 in 2025
365
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Bartholomew, Indiana on 365 days. 265 of those days (73%) were in the Good range, and the median daily AQI was 43. That median is about the same as the typical monitored county in Indiana (median 41 across 33 counties), and higher than the typical monitored U.S. county (40). The main pollutant was ozone on 208 days. Across the years with fuller monitoring, the share of Good days fell: an average of 78% in 1989–2000 versus 70% in 2023–2025.

Years with fewer than 120 monitored days (1991) 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%1989: Good 155 of 203 days1989: Moderate 38 of 203 days1989: Unhealthy for Sensitive Groups 9 of 203 days1989: Unhealthy 1 of 203 days19891990: Good 130 of 208 days1990: Moderate 50 of 208 days1990: Unhealthy for Sensitive Groups 22 of 208 days1990: Unhealthy 6 of 208 days1991: Good 48 of 92 days1991: Moderate 35 of 92 days1991: Unhealthy for Sensitive Groups 9 of 92 days19912000: Good 124 of 131 days2000: Moderate 7 of 131 days2001: Good 211 of 222 days2001: Moderate 11 of 222 days20012013: Good 175 of 214 days2013: Moderate 39 of 214 days2014: Good 234 of 364 days2014: Moderate 129 of 364 days2014: Unhealthy for Sensitive Groups 1 of 364 days20142015: Good 178 of 365 days2015: Moderate 185 of 365 days2015: Unhealthy for Sensitive Groups 2 of 365 days2016: Good 211 of 366 days2016: Moderate 150 of 366 days2016: Unhealthy for Sensitive Groups 5 of 366 days20162017: Good 256 of 364 days2017: Moderate 108 of 364 days2018: Good 242 of 365 days2018: Moderate 119 of 365 days2018: Unhealthy for Sensitive Groups 4 of 365 days20182019: Good 256 of 364 days2019: Moderate 108 of 364 days2020: Good 275 of 366 days2020: Moderate 91 of 366 days20202021: Good 252 of 364 days2021: Moderate 112 of 364 days2022: Good 280 of 365 days2022: Moderate 84 of 365 days2022: Unhealthy for Sensitive Groups 1 of 365 days20222023: Good 234 of 361 days2023: Moderate 119 of 361 days2023: Unhealthy for Sensitive Groups 7 of 361 days2023: Very Unhealthy 1 of 361 days2024: Good 262 of 366 days2024: Moderate 103 of 366 days2024: Unhealthy for Sensitive Groups 1 of 366 days20242025: Good 265 of 365 days2025: Moderate 100 of 365 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 year0501001501989: 90th percentile AQI 771990: 90th percentile AQI 1121991: 90th percentile AQI 1002000: 90th percentile AQI 412001: 90th percentile AQI 432013: 90th percentile AQI 672014: 90th percentile AQI 672015: 90th percentile AQI 692016: 90th percentile AQI 662017: 90th percentile AQI 582018: 90th percentile AQI 632019: 90th percentile AQI 582020: 90th percentile AQI 572021: 90th percentile AQI 612022: 90th percentile AQI 572023: 90th percentile AQI 642024: 90th percentile AQI 582025: 90th percentile AQI 591989: Median AQI 401990: Median AQI 461991: Median AQI 482000: Median AQI 192001: Median AQI 192013: Median AQI 352014: Median AQI 432015: Median AQI 512016: Median AQI 472017: Median AQI 432018: Median AQI 442019: Median AQI 442020: Median AQI 412021: Median AQI 432022: Median AQI 412023: Median AQI 462024: Median AQI 442025: Median AQI 431989199120012014201620182020202220242025
  • 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
Ozone20857%
Fine particles (PM2.5)15743%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253652651000000435997Ozone
202436626210310004458101Ozone
202336123411970104664215Ozone
20223652808410004157105Ozone
20213642521120000436193PM2.5
2020366275910000415797Ozone
20193642561080000445877Ozone
201836524211940004463108Ozone
20173642561080000435893PM2.5
201636621115050004766105PM2.5
201536517818520005169115PM2.5
201436423412910004367108PM2.5
2013214175390000356793Ozone
2001222211110000194361PM10
200013112470000194158PM10
1991924835900048100140Ozone
1990208130502260046112195Ozone
19892031553891004077154Ozone

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 1989–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem