Median AQI
45
Good
Indiana · County air quality · 2025
Vigo County, Indiana
Median AQI 45 (Good). 62.0% of monitored days rated Good, direct from EPA Air Quality System stations.
- 45
- Median AQI
- 62.0%
- Good-air days
- 0
- Unhealthy days
- 18%
- Cleaner than US counties
The verdict
According to EPA Air Quality System monitoring data, Vigo County's air is good on balance, among the more polluted 10% of US counties, a median AQI of 45 with 62.0% of 300 monitored days in the Good band, driven mainly by PM2.5.
- 45
- median AQI · Good
- 62.0%
- days rated Good
- PM2.5
- main pollutant
- 18%
- cleaner than US counties
Not one day crossed into the Unhealthy tier; the worst single reading was AQI 108.
Data updated July 2026
- Good · 186 d · 62.0%
- Moderate · 113 d · 37.7%
- USG · 1 d · 0.3%
How did Vigo County's air break down in 2025?
Across 300 monitored days, 186 fell in the Good band (AQI 0–50) and 0 reached Unhealthy or worse. The worst single day peaked at AQI 108 (USG).
EPA AQS →Air quality data from EPA Air Quality System (2025). 300 days monitored. Median AQI: 45 (Good).
Insights: Vigo County, Indiana. EPA monitors recorded a median Air Quality Index of 45 across 300 measured days in 2025, earning a Good classification and a Moderate health grade. Of those days, 186 (62%) fell in the Good band (AQI 0–50), 113 (38%) registered Moderate readings, and 1 (0%) reached Unhealthy for Sensitive Groups. The 90th-percentile AQI settled at 65, while the worst single-day peak hit 108 (USG). Residents averaged about 18.6 clean-air days per 30-day window during the monitoring year.
The full pollutant mix ranks as PM2.5 (182 days), Ozone (118 days). Across the 2020–2025 trend window, good days shifted by -37 and the median AQI moved -1 points, placing the multi-year trajectory at stable. The worst single reading over the 2020–2025 window was AQI 108, usg but never Unhealthy. Nearby counties show comparable readings: Allen (58.2% good, AQI 45); Bartholomew (69.2% good, AQI 44); Boone (86.9% good, AQI 38); Brown (94.5% good, AQI 37); Carroll (87.8% good, AQI 37); Clark (59.7% good, AQI 46).
Air Quality Summary
Good Days
62.0%
186 of 300 monitored days
-13.0pp vs 75% target
Max AQI Recorded
108
USG
Health Grade
Moderate
90th-pct AQI 65
Vigo County, Good days share 62.0%
National avg
Share of monitored days at AQI 0-50 (Good band).
Vigo 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 300 monitored days across EPA AQI categories.
Good
186
62%
Moderate
113
38%
USG
1
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 Vigo County.
- PM2.5 · 182 days · 60.7%
- Ozone · 118 days · 39.3%
Health Impact Assessment
Moderate
Vigo County's air quality is rated Moderate based on 62.0% good air days. No unhealthy air days were recorded in 2025.
Air quality was acceptable on 62.0% of monitored days in 2025, with a median AQI of 45. Unusually sensitive people can check real-time conditions at AirNow.gov during high-pollution events.
The dominant pollutant is PM2.5, driving AQI on 182 of 300 monitored days.
5-Year Air Quality Trend
Air quality is stable in Vigo County. Best year: 2020 (223 good days).
| Year | Good | Moderate | USG | Unhealthy | Median AQI | Max AQI |
|---|---|---|---|---|---|---|
| 2020 | 223 | 142 | 1 | 0 | 46 | 112 |
| 2021 | 172 | 193 | 0 | 0 | 51 | 99 |
| 2022 | 203 | 160 | 2 | 0 | 47 | 115 |
| 2023 | 182 | 175 | 6 | 1 | 51 | 232 |
| 2024 | 204 | 161 | 1 | 0 | 47 | 112 |
| 2025 | 186 | 113 | 1 | 0 | 45 | 108 |
How does Vigo County compare?
How Vigo County compares
Good-day share worse than US avg
Vigo County 62.0%
Allen County, Indiana 58.2%
US average 76.5%
Median AQI worse than US avg
Vigo County 45
Allen County, Indiana 45
US average 38
Unhealthy days / yr about average
Vigo County 0
Allen County, Indiana 0
US average 0
Other Counties in Indiana
Air quality comparison for nearby counties in Indiana.
Counties with Similar Air Quality
Counties across the US with a similar median AQI to Vigo County.
Adair County, Oklahoma
AQI 45 · 59.2% good
Allen County, Indiana
AQI 45 · 58.2% good
Atascosa County, Texas
AQI 45 · 58.0% good
Baker County, Florida
AQI 45 · 69.1% good
Carson City County, Nevada
AQI 45 · 79.3% good
Clinton County, Iowa
AQI 45 · 59.9% good
What Vigo County's air means for you
The air here stays in the breathable range year-round, with PM2.5 the main thing to watch.
- Sensitive groups (asthma, heart conditions, children, older adults) should check the AQI on high-PM2.5 days, the guide explains what a median of 45 means for exposure. Health guidance
- See how Vigo County ranks against every monitored U.S. county on Good-day share. County rankings
- Compare Vigo County with its Indiana neighbours before drawing a conclusion about the region. All of Indiana
Based on 300 EPA-monitored days in 2025; figures reflect only days the monitors reported. Source: EPA Air Quality System annual summaries.
More Air Quality Data
Air Quality Guides
Frequently Asked Questions
What is the air quality in Vigo County, Indiana? ▼
Vigo County has a median Air Quality Index (AQI) of 45, rated "Good." 62.0% of monitored days (186 out of 300) had good air quality in 2025.
What is the main pollutant in Vigo County? ▼
The primary pollutant in Vigo County is Fine Particles (PM2.5), which was the main AQI driver on 182 days (61% of monitored days). Penetrates deep into lungs and bloodstream. Linked to heart disease and premature death.
How many unhealthy air days does Vigo County have? ▼
In 2025, Vigo County recorded 0 unhealthy air days (0 Unhealthy, 0 Very Unhealthy, 0 Hazardous). The maximum AQI reached 108.
Is the air quality in Vigo County getting better or worse? ▼
Air quality in Vigo County is stable based on 5-year trends (2020-2025). Best year: 2020 with 223 good days. Worst year: 2021 with 172 good days.
What does AQI 45 mean for health? ▼
Vigo County's median AQI of 45 falls in the "Good" category. See the <a href="/guides/understanding-aqi" class="underline">AQI category guide</a> for what each range means for health.
How does Vigo County compare to other counties in Indiana? ▼
Vigo County has 62.0% good air days. Nearby counties in Indiana: Allen (58.2% good), Bartholomew (69.2% good), Boone (86.9% good), Brown (94.5% good), Carroll (87.8% good), Clark (59.7% good).
What is the 90th percentile AQI in Vigo County? ▼
The 90th percentile AQI for Vigo County is 65, meaning 90% of monitored days had an AQI at or below this level. The maximum AQI recorded was 108 (USG).
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.
Every figure on PlainAir 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.