Monroe City, Indiana Air Quality
Monroe City has a median AQI of 38, earning an air quality grade of A — excellent air quality that ranks better than 70% of US cities. Air quality has remained relatively stable over the past decade. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, Monroe City recorded 215 good air quality days (93% of monitored days).
Population: 767 • County: Knox
Current AQI
Quick Facts
| Current AQI | 7 — Good |
| Air Quality Grade | A |
| Median AQI (2025) | 38 |
| vs. U.S. Cities | Better than 70% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 0 |
| 10-Year Trend | → Stable |
| Data Source | EPA AQS (historical) · AirNow (live) |
Health Recommendation
Air quality is satisfactory, and air pollution poses little or no risk.
It's a great day to be active outside!
5-Day AQI Forecast
Last 90 Days
Current Pollutant Levels
Real-time data from EPA AirNow
Local Air Quality Context
Air quality data for Monroe City is sourced from the Jasper - Post Office monitoring area, located approximately 28 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
Monroe City typically sees its worst air quality during summer afternoons when heat and sunlight drive ground-level ozone formation from vehicle and industrial emissions. Morning readings are generally 15–25 points lower than afternoon peaks. Outdoor activity is best planned for early morning on high-ozone days.
AQI Trend (10 Years)
Air Quality Days by Year
Monroe City Median AQI by Year
Annual EPA air quality data for Monroe City — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 38 | 215 | — | 93 | Ozone |
| 2024 | 38 | 314 | — | 90 | Ozone |
| 2023 | 39 | 313 | 8 | 126 | Ozone |
| 2022 | 36 | 321 | — | 87 | Ozone |
| 2021 | 36 | 320 | 2 | 108 | Ozone |
| 2020 | 33 | 328 | 1 | 105 | Ozone |
| 2019 | 36 | 328 | — | 87 | Ozone |
| 2018 | 35 | 311 | 4 | 122 | Ozone |
| 2017 | 36 | 323 | — | 100 | Ozone |
| 2016 | 35 | 313 | 4 | 119 | Ozone |
Source: EPA Air Quality System (AQS) annual summaries. "Unhealthy Days" includes Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, and Hazardous categories.
2025 Air Quality Summary
Primary Pollutant Days (2025)
Days when each pollutant was the primary driver of AQI. Learn about pollutants →
Frequently Asked Questions About Monroe City Air Quality
What is the air quality in Monroe City today?
The current AQI in Monroe City is 7, rated "Good". Air quality is good — outdoor activity is safe for everyone today. Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in Monroe City getting better or worse?
Air quality in Monroe City has been stable. The median AQI has risen 3 points (from 35 in 2016 to 38 in 2025).
What is the most common air pollutant in Monroe City?
Ozone is the primary air pollutant in Monroe City, responsible for 231 days (100% of monitored days) in 2025. Ground-level ozone forms when sunlight reacts with emissions from vehicles and industry, typically peaking on hot summer afternoons.
How many unhealthy air days does Monroe City have per year?
In 2025, Monroe City recorded 93% good air quality days (215 days) out of 231 monitored days. There were 0 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 93.
What air quality grade does Monroe City receive?
Monroe City receives an air quality grade of A, placing it better than 70% of US cities. This is based on a median AQI of 38 in 2025, with 215 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 70% of US cities
Nearby Cities
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National Rankings
See how Monroe City compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for Monroe City
Monroe City has a summer ozone problem — hot afternoons push AQI into Moderate or higher as sunlight converts vehicle and industrial emissions into ground-level ozone. Activated carbon and PECO filters chemically neutralize ozone rather than just trapping particles.
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