EnviroNearby

Carroll County, Indiana air quality history

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

91%
Good days in 2025
35
Median daily AQI, 2025
1
Days above 100 in 2025
347
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Carroll, Indiana on 347 days. 315 of those days (91%) were in the Good range, and the median daily AQI was 35. 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 ozone on 347 days. Across the years with fuller monitoring, the share of Good days rose: an average of 73% in 1989–1991 versus 89% 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%1989: Good 140 of 192 days1989: Moderate 43 of 192 days1989: Unhealthy for Sensitive Groups 8 of 192 days1989: Unhealthy 1 of 192 days19891990: Good 152 of 193 days1990: Moderate 34 of 193 days1990: Unhealthy for Sensitive Groups 7 of 193 days1991: Good 120 of 176 days1991: Moderate 40 of 176 days1991: Unhealthy for Sensitive Groups 13 of 176 days1991: Unhealthy 3 of 176 days19912001: Good 106 of 168 days2001: Moderate 47 of 168 days2001: Unhealthy for Sensitive Groups 14 of 168 days2001: Unhealthy 1 of 168 days2002: Good 86 of 182 days2002: Moderate 65 of 182 days2002: Unhealthy for Sensitive Groups 20 of 182 days2002: Unhealthy 11 of 182 days20022003: Good 115 of 183 days2003: Moderate 57 of 183 days2003: Unhealthy for Sensitive Groups 10 of 183 days2003: Unhealthy 1 of 183 days2004: Good 129 of 174 days2004: Moderate 41 of 174 days2004: Unhealthy for Sensitive Groups 4 of 174 days20042005: Good 87 of 154 days2005: Moderate 55 of 154 days2005: Unhealthy for Sensitive Groups 12 of 154 days2006: Good 117 of 172 days2006: Moderate 51 of 172 days2006: Unhealthy for Sensitive Groups 4 of 172 days20062007: Good 110 of 161 days2007: Moderate 42 of 161 days2007: Unhealthy for Sensitive Groups 9 of 161 days2008: Good 153 of 181 days2008: Moderate 28 of 181 days20082009: Good 155 of 180 days2009: Moderate 25 of 180 days2010: Good 139 of 182 days2010: Moderate 39 of 182 days2010: Unhealthy for Sensitive Groups 4 of 182 days20102011: Good 147 of 171 days2011: Moderate 23 of 171 days2011: Unhealthy for Sensitive Groups 1 of 171 days2012: Good 122 of 182 days2012: Moderate 50 of 182 days2012: Unhealthy for Sensitive Groups 9 of 182 days2012: Unhealthy 1 of 182 days20122013: Good 139 of 176 days2013: Moderate 37 of 176 days2014: Good 144 of 173 days2014: Moderate 28 of 173 days2014: Unhealthy for Sensitive Groups 1 of 173 days20142015: Good 155 of 183 days2015: Moderate 28 of 183 days2016: Good 147 of 182 days2016: Moderate 33 of 182 days2016: Unhealthy for Sensitive Groups 2 of 182 days20162017: Good 210 of 232 days2017: Moderate 22 of 232 days2018: Good 337 of 359 days2018: Moderate 19 of 359 days2018: Unhealthy for Sensitive Groups 3 of 359 days20182019: Good 333 of 358 days2019: Moderate 25 of 358 days2020: Good 352 of 364 days2020: Moderate 12 of 364 days20202021: Good 338 of 365 days2021: Moderate 26 of 365 days2021: Unhealthy for Sensitive Groups 1 of 365 days2022: Good 343 of 364 days2022: Moderate 21 of 364 days20222023: Good 308 of 351 days2023: Moderate 38 of 351 days2023: Unhealthy for Sensitive Groups 5 of 351 days2024: Good 317 of 361 days2024: Moderate 44 of 361 days20242025: Good 315 of 347 days2025: Moderate 31 of 347 days2025: Unhealthy for Sensitive Groups 1 of 347 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 931990: 90th percentile AQI 801991: 90th percentile AQI 1002001: 90th percentile AQI 1002002: 90th percentile AQI 1262003: 90th percentile AQI 902004: 90th percentile AQI 842005: 90th percentile AQI 1002006: 90th percentile AQI 742007: 90th percentile AQI 902008: 90th percentile AQI 612009: 90th percentile AQI 612010: 90th percentile AQI 742011: 90th percentile AQI 582012: 90th percentile AQI 902013: 90th percentile AQI 672014: 90th percentile AQI 582015: 90th percentile AQI 642016: 90th percentile AQI 612017: 90th percentile AQI 502018: 90th percentile AQI 482019: 90th percentile AQI 492020: 90th percentile AQI 442021: 90th percentile AQI 482022: 90th percentile AQI 472023: 90th percentile AQI 542024: 90th percentile AQI 542025: 90th percentile AQI 491989: Median AQI 431990: Median AQI 391991: Median AQI 442001: Median AQI 472002: Median AQI 542003: Median AQI 462004: Median AQI 442005: Median AQI 482006: Median AQI 452007: Median AQI 452008: Median AQI 422009: Median AQI 402010: Median AQI 452011: Median AQI 402012: Median AQI 472013: Median AQI 432014: Median AQI 412015: Median AQI 432016: Median AQI 392017: Median AQI 392018: Median AQI 322019: Median AQI 352020: Median AQI 312021: Median AQI 342022: Median AQI 342023: Median AQI 362024: Median AQI 362025: Median AQI 35198919912002200420062008201020122014201620182020202220242025
  • 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
Ozone347100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
20253473153110003549105Ozone
2024361317440000365490Ozone
20233513083850003654122Ozone
2022364343210000344793Ozone
20213653382610003448105Ozone
20203643521200003144100Ozone
2019358333250000354984Ozone
20183593371930003248115Ozone
2017232210220000395077Ozone
20161821473320003961101Ozone
2015183155280000436487Ozone
20141731442810004158108Ozone
2013176139370000436797Ozone
20121821225091004790156Ozone
20111711472310004058122Ozone
20101821393940004574119Ozone
2009180155250000406187Ozone
2008181153280000426197Ozone
20071611104290004590150Ozone
20061721175140004574119Ozone
200515487551200048100119Ozone
20041741294140004484115Ozone
200318311557101004690156Ozone
2002182866520110054126197Ozone
2001168106471410047100154Ozone
1991176120401330044100174Ozone
19901931523470003980150Ozone
19891921404381004393169Ozone

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