Median AQI
43
Good
Indiana · County air quality · 2025
Bartholomew County, Indiana
Median AQI 43 (Good). 72.6% of monitored days rated Good, direct from EPA Air Quality System stations.
- 43
- Median AQI
- 72.6%
- Good-air days
- 0
- Unhealthy days
- 38%
- Cleaner than US counties
Bartholomew County's 2025 annual median AQI is 43 (Good), with 72.6% Good days
According to the U.S. EPA Air Quality System, Bartholomew County, Indiana posted a 2025 median AQI of 43 (Good) across 365 monitored days, with 72.6% rated Good and 0 unhealthy or worse. This is an annual comparison, not today's advisory.
Data source EPA Air Quality System (AQS)
- Cleaner than US
- Bartholomew County's 72.6% Good-day share places it cleaner than 38% of US counties in 2025.
- Closest median-AQI peer
- Ashtabula County (81.2% Good, median AQI 43) is the closest nationwide median-AQI peer to Bartholomew County.
- 2020–2025 trend
- Bartholomew County's floor-qualifying Good-day share is stable from 2020 to 2025 (75.1% → 72.6%).
- Median AQI
- Median AQI: 43
The verdict
According to EPA Air Quality System monitoring data, Bartholomew County's air is good on balance, more polluted than the median US county, a median AQI of 43 with 72.6% of 365 monitored days in the Good band, driven mainly by Ozone.
- 43
- median AQI · Good
- 72.6%
- days rated Good
- Ozone
- main pollutant
- 38%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 97.
Annual release change
What changed in the 2025 EPA annual release
- Bartholomew County's Good-day share rose from 71.6% to 72.6% between the 2024 and 2025 EPA annual releases, a change of +1.0 percentage points.
Data updated August 2026
- Good · 265 d · 72.6%
- Moderate · 100 d · 27.4%
How did Bartholomew County's air break down in 2025?
Across 365 monitored days, 265 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 97 (Moderate).
EPA AQS →Air quality data from EPA Air Quality System (2025). 365 days monitored. Median AQI: 43 (Good).
Insights: Bartholomew County, Indiana. EPA monitors recorded a median Air Quality Index of 43 across 365 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 265 (73%) fell in the Good band (AQI 0–50), 100 (27%) registered Moderate readings, and 0 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 59, while the worst single-day peak hit 97 (Moderate). Residents averaged about 21.8 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as Ozone (208 days), PM2.5 (157 days). Across the 2020–2025 trend window, the share of monitored days rated Good shifted by -2.5 points and the median AQI moved +2 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 97, moderate but never Unhealthy. Nearby counties show comparable readings: Allen (60.0% good, AQI 44); Boone (89.7% good, AQI 35); Brown (95.9% good, AQI 34); Carroll (90.8% good, AQI 35); Clark (58.1% good, AQI 46); Delaware (64.7% good, AQI 43).
Air Quality Summary
Good Days
72.6%
265 of 365 monitored days
-2.4pp vs 75% target
Max AQI Recorded
97
Moderate
Health Grade
Moderate
90th-pct AQI 59
Bartholomew County, Good days share 72.6%
National avg
Share of monitored days at AQI 0-50 (Good band).
Bartholomew County, Unhealthy-or-worse share 0.0%
National avg
Share of monitored days above AQI 150 (Unhealthy or worse). Bar maxes at 10% (worst-county ceiling).
AQI Day Breakdown (2025)
Distribution of 365 monitored days across EPA AQI categories.
Good
265
73%
Moderate
100
27%
USG
0
0%
Unhealthy
0
0%
Very Unhealthy
0
0%
Hazardous
0
0%
Pollutant Breakdown
Days where each pollutant was the primary driver of AQI readings in Bartholomew County.
- Ozone · 208 days · 57.0%
- PM2.5 · 157 days · 43.0%
Health Impact Assessment
Moderate
Bartholomew County's air quality is rated Moderate based on 72.6% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 72.6% of monitored days in 2025, with a median AQI of 43. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is Ozone, driving AQI on 208 of 365 monitored days.
5-Year Air Quality Trend
Air quality is stable in Bartholomew County. Highest Good-day share: 2022 (76.7%, 280 of 365 monitored days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 275 | 91 | 0 | 0 | 41 | 97 |
| 2021 | 252 | 112 | 0 | 0 | 43 | 93 |
| 2022 | 280 | 84 | 1 | 0 | 41 | 105 |
| 2023 | 234 | 119 | 7 | 0 | 46 | 215 |
| 2024 | 262 | 103 | 1 | 0 | 44 | 101 |
| 2025 | 265 | 100 | 0 | 0 | 43 | 97 |
How does Bartholomew County compare?
How Bartholomew County compares
Good-day share worse than US avg
Bartholomew County 72.6%
Ashtabula County, Ohio 81.2%
US average 76.0%
Median AQI worse than US avg
Bartholomew County 43
Ashtabula County, Ohio 43
US average 39
Unhealthy days / yr better than US avg
Bartholomew County 0
Ashtabula County, Ohio 0
US average 1
Counties with a similar median AQI
Nationwide peers within about the same annual median AQI as Bartholomew County (43), not geographic neighbors.
Ashtabula County, Ohio
Median AQI 43 · 81.2% Good-day share
Baltimore (City) County, Maryland
Median AQI 43 · 68.1% Good-day share
Berks County, Pennsylvania
Median AQI 43 · 68.2% Good-day share
Bolivar County, Mississippi
Median AQI 43 · 71.9% Good-day share
Brewster County, Texas
Median AQI 43 · 74.7% Good-day share
Broward County, Florida
Median AQI 43 · 73.4% Good-day share
Same primary pollutant: Ozone
Ozone led the AQI on the most monitored days here. These peers share that driver and the closest Good-day share (a second relationship type beyond median-AQI neighbors).
Ingham County, Michigan
72.6% Good-day share · median AQI 38
Mercer County, Pennsylvania
72.6% Good-day share · median AQI 42
Suffolk County, New York
72.6% Good-day share · median AQI 41
Gunnison County, Colorado
72.5% Good-day share · median AQI 46
Jersey County, Illinois
72.3% Good-day share · median AQI 42
Dodge County, Wisconsin
72.3% Good-day share · median AQI 40
Indiana counties on the map
Geographic containment only, other monitored counties in Indiana, independent of AQI or pollutant match.
What Bartholomew County's air means for you
The air here stays in the breathable range year-round, with Ozone the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-Ozone days, the guide explains what a median of 43 means for exposure. Health guidance
- See how Bartholomew County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Bartholomew County with its Indiana neighbours before drawing a conclusion about the region. All of Indiana
Based on 365 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
Keep exploring the annual AQI record
Air-quality reading list
Frequently Asked Questions
What is the air quality in Bartholomew County, Indiana? ▼
Bartholomew County has a median Air Quality Index (AQI) of 43, rated "Good." 72.6% of monitored days (265 out of 365) had good air quality in 2025.
What is the main pollutant in Bartholomew County? ▼
The primary pollutant in Bartholomew County is Ozone (O3), which was the main AQI driver on 208 days (57% of monitored days). Can trigger asthma, reduce lung function, and cause chest pain.
How many unhealthy air days does Bartholomew County have? ▼
In 2025, Bartholomew County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 97.
Is the air quality in Bartholomew County getting better or worse? ▼
Air quality in Bartholomew County is stable across floor-qualifying years (2020-2025); years with fewer than 100 monitored days are excluded from that direction. Highest qualifying Good-day share: 2022 at 76.7% (280 of 365 days). Lowest qualifying Good-day share: 2023 at 65.0% (234 of 361 days).
What does AQI 43 mean for health? ▼
Bartholomew County's median AQI of 43 falls in the "Good" category. See the AQI category guide for what each range means for health.
How does Bartholomew County compare to other counties in Indiana? ▼
Bartholomew County has 72.6% good air days. Nearby counties in Indiana: Allen (60.0% good), Boone (89.7% good), Brown (95.9% good), Carroll (90.8% good), Clark (58.1% good), Delaware (64.7% good).
What is the 90th percentile AQI in Bartholomew County? ▼
The 90th percentile AQI for Bartholomew County is 59, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 97 (Moderate).
Data Sources
Primary Source: U.S. Environmental Protection Agency (EPA), Air Quality System (AQS), Annual AQI by County dataset, 2020–2025 (aqs.epa.gov). For current conditions (not shown here — this page is historical annual data), see EPA AirNow (airnow.gov). See our methodology for how AQI, median, and coverage figures are computed.
Informational only, not professional advice. Data from EPA AQS. See our disclaimer. Spotted a figure that looks wrong? Report a correction.
Source: U.S. EPA Air Quality System (AQS) Annual AQI by county summary files for Bartholomew County, Indiana · 2020–2025
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Every figure on PlainAirData is rendered directly from EPA AQS air-quality monitoring data, no number is typed in by an editor. This page draws directly on EPA AQS air-quality monitoring data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.