EnviroNearby

Hendricks County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Hendricks, Indiana, 1998–2025.

92%
Good days in 2025
35
Median daily AQI, 2025
0
Days above 100 in 2025
362
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Hendricks, Indiana on 362 days. 333 of those days (92%) 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 362 days. Across the years with fuller monitoring, the share of Good days rose: an average of 42% in 1998–2000 versus 92% 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%1998: Good 92 of 230 days1998: Moderate 69 of 230 days1998: Unhealthy for Sensitive Groups 69 of 230 days19981999: Good 79 of 183 days1999: Moderate 47 of 183 days1999: Unhealthy for Sensitive Groups 55 of 183 days1999: Unhealthy 2 of 183 days2000: Good 114 of 275 days2000: Moderate 88 of 275 days2000: Unhealthy for Sensitive Groups 65 of 275 days2000: Unhealthy 7 of 275 days2000: Very Unhealthy 1 of 275 days20002001: Good 99 of 183 days2001: Moderate 57 of 183 days2001: Unhealthy for Sensitive Groups 25 of 183 days2001: Unhealthy 2 of 183 days2002: Good 93 of 180 days2002: Moderate 53 of 180 days2002: Unhealthy for Sensitive Groups 26 of 180 days2002: Unhealthy 7 of 180 days2002: Very Unhealthy 1 of 180 days20022003: Good 168 of 243 days2003: Moderate 58 of 243 days2003: Unhealthy for Sensitive Groups 15 of 243 days2003: Unhealthy 2 of 243 days2004: Good 294 of 366 days2004: Moderate 63 of 366 days2004: Unhealthy for Sensitive Groups 9 of 366 days20042005: Good 287 of 365 days2005: Moderate 59 of 365 days2005: Unhealthy for Sensitive Groups 18 of 365 days2005: Unhealthy 1 of 365 days2006: Good 313 of 365 days2006: Moderate 45 of 365 days2006: Unhealthy for Sensitive Groups 7 of 365 days20062007: Good 287 of 365 days2007: Moderate 56 of 365 days2007: Unhealthy for Sensitive Groups 22 of 365 days2008: Good 314 of 356 days2008: Moderate 40 of 356 days2008: Unhealthy for Sensitive Groups 2 of 356 days20082009: Good 222 of 272 days2009: Moderate 47 of 272 days2009: Unhealthy for Sensitive Groups 3 of 272 days2010: Good 146 of 183 days2010: Moderate 37 of 183 days20102011: Good 145 of 182 days2011: Moderate 35 of 182 days2011: Unhealthy for Sensitive Groups 2 of 182 days2012: Good 122 of 182 days2012: Moderate 56 of 182 days2012: Unhealthy for Sensitive Groups 4 of 182 days20122013: Good 168 of 179 days2013: Moderate 11 of 179 days2014: Good 175 of 183 days2014: Moderate 8 of 183 days20142015: Good 179 of 183 days2015: Moderate 4 of 183 days2016: Good 146 of 183 days2016: Moderate 37 of 183 days20162017: Good 220 of 240 days2017: Moderate 20 of 240 days2018: Good 335 of 365 days2018: Moderate 28 of 365 days2018: Unhealthy for Sensitive Groups 2 of 365 days20182019: Good 348 of 361 days2019: Moderate 13 of 361 days2020: Good 348 of 366 days2020: Moderate 18 of 366 days20202021: Good 347 of 365 days2021: Moderate 18 of 365 days2022: Good 338 of 352 days2022: Moderate 14 of 352 days20222023: Good 324 of 360 days2023: Moderate 32 of 360 days2023: Unhealthy for Sensitive Groups 4 of 360 days2024: Good 331 of 353 days2024: Moderate 22 of 353 days20242025: Good 333 of 362 days2025: Moderate 29 of 362 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 year0501001501998: 90th percentile AQI 1181999: 90th percentile AQI 1182000: 90th percentile AQI 1142001: 90th percentile AQI 1082002: 90th percentile AQI 1332003: 90th percentile AQI 932004: 90th percentile AQI 622005: 90th percentile AQI 842006: 90th percentile AQI 662007: 90th percentile AQI 902008: 90th percentile AQI 512009: 90th percentile AQI 642010: 90th percentile AQI 672011: 90th percentile AQI 642012: 90th percentile AQI 802013: 90th percentile AQI 492014: 90th percentile AQI 472015: 90th percentile AQI 452016: 90th percentile AQI 672017: 90th percentile AQI 502018: 90th percentile AQI 482019: 90th percentile AQI 472020: 90th percentile AQI 452021: 90th percentile AQI 462022: 90th percentile AQI 462023: 90th percentile AQI 512024: 90th percentile AQI 482025: 90th percentile AQI 491998: Median AQI 641999: Median AQI 622000: Median AQI 602001: Median AQI 482002: Median AQI 502003: Median AQI 412004: Median AQI 362005: Median AQI 342006: Median AQI 292007: Median AQI 322008: Median AQI 302009: Median AQI 372010: Median AQI 412011: Median AQI 402012: Median AQI 452013: Median AQI 382014: Median AQI 362015: Median AQI 352016: Median AQI 402017: Median AQI 382018: Median AQI 332019: Median AQI 342020: Median AQI 322021: Median AQI 332022: Median AQI 342023: Median AQI 372024: Median AQI 352025: Median AQI 35199820002002200420062008201020122014201620182020202220242025
  • 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
Ozone362100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025362333290000354990Ozone
2024353331220000354880Ozone
20233603243240003751119Ozone
2022352338140000344687Ozone
2021365347180000334680Ozone
2020366348180000324587Ozone
2019361348130000344793Ozone
20183653352820003348108Ozone
2017240220200000385093Ozone
20161831463700004067100Ozone
201518317940000354561Ozone
201418317580000364777Ozone
2013179168110000384974Ozone
20121821225640004580143Ozone
20111821453520004064105Ozone
20101831463700004167100Ozone
20092722224730003764140Ozone
20083563144020003051115Ozone
200736528756220003290143Ozone
20063653134570002966129Ozone
200536528759181003484154NO2
20043662946390003662115Ozone
200324316858152004193156Ozone
200218093532671050133209Ozone
200118399572520048108159Ozone
2000275114886571060114204NO2
199918379475520062118166NO2
199823092696900064118149NO2

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 1998–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem