EnviroNearby

Brown County, Indiana air quality history

Daily Air Quality Index summaries from EPA monitors in Brown, Indiana, 2014–2025.

96%
Good days in 2025
34
Median daily AQI, 2025
0
Days above 100 in 2025
364
Days with an AQI in 2025 (of 365)

In 2025, EPA reported a daily Air Quality Index (AQI) for Brown, Indiana on 364 days. 349 of those days (96%) were in the Good range, and the median daily AQI was 34. 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 364 days. Across the years with fuller monitoring, the share of Good days rose: an average of 90% in 2015–2017 versus 94% in 2023–2025.

Years with fewer than 120 monitored days (2014) 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%2014: Good 112 of 119 days2014: Moderate 7 of 119 days20142015: Good 166 of 181 days2015: Moderate 14 of 181 days2015: Unhealthy for Sensitive Groups 1 of 181 days20152016: Good 123 of 138 days2016: Moderate 14 of 138 days2016: Unhealthy for Sensitive Groups 1 of 138 days20162017: Good 207 of 233 days2017: Moderate 26 of 233 days20172018: Good 339 of 363 days2018: Moderate 24 of 363 days20182019: Good 349 of 365 days2019: Moderate 16 of 365 days20192020: Good 349 of 364 days2020: Moderate 15 of 364 days20202021: Good 341 of 361 days2021: Moderate 20 of 361 days20212022: Good 348 of 358 days2022: Moderate 10 of 358 days20222023: Good 313 of 347 days2023: Moderate 32 of 347 days2023: Unhealthy for Sensitive Groups 2 of 347 days20232024: Good 339 of 359 days2024: Moderate 20 of 359 days20242025: Good 349 of 364 days2025: Moderate 15 of 364 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 year0501002014: 90th percentile AQI 492015: 90th percentile AQI 492016: 90th percentile AQI 542017: 90th percentile AQI 512018: 90th percentile AQI 482019: 90th percentile AQI 472020: 90th percentile AQI 442021: 90th percentile AQI 462022: 90th percentile AQI 462023: 90th percentile AQI 502024: 90th percentile AQI 492025: 90th percentile AQI 462014: Median AQI 392015: Median AQI 382016: Median AQI 362017: Median AQI 392018: Median AQI 332019: Median AQI 352020: Median AQI 332021: Median AQI 332022: Median AQI 352023: Median AQI 372024: Median AQI 372025: Median AQI 34201420152016201720182019202020212022202320242025
  • 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
Ozone364100%

Year-by-year data

Annual AQI summary by year
YearDays with AQIGoodModerateUnhealthy for Sensitive GroupsUnhealthyVery UnhealthyHazardousMedian AQI90th pct.Max AQIMain pollutant
2025364349150000344677Ozone
2024359339200000374977Ozone
20233473133220003750126Ozone
2022358348100000354697Ozone
2021361341200000334684Ozone
2020364349150000334480Ozone
2019365349160000354774Ozone
2018363339240000334897Ozone
2017233207260000395190Ozone
20161381231410003654101Ozone
20151811661410003849101Ozone
201411911270000394971Ozone

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 2014–2025 (EPA download page). EPA file dates: 2026-06-26. Imported into EnviroNearby November 5, 2026. How we use this data · Report a problem