North Liberty, Indiana Air Quality
North Liberty has a median AQI of 44, earning an air quality grade of A- — excellent air quality that ranks better than 31% of US cities. Air quality has been improving steadily over the past decade, a positive sign for residents. Ground-level ozone is the primary concern, typically peaking on warm sunny days due to vehicle and industrial emissions. In 2025, North Liberty recorded 172 good air quality days (63% of monitored days) and 7 unhealthy days.
Population: 1,775 • County: St. Joseph
Current AQI
Quick Facts
| Current AQI | 13 — Good |
| Air Quality Grade | A- |
| Median AQI (2025) | 44 |
| vs. U.S. Cities | Better than 31% |
| Primary Pollutant | Ozone |
| Unhealthy Days/Year | 7 |
| 10-Year Trend | ↑ Improving |
| 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 North Liberty is sourced from the South Bend-Shields Dr monitoring area, located approximately 16 miles from city center. This EPA-certified station continuously tracks ground-level ozone, the primary driver of air quality alerts in this area.
North Liberty tends to see elevated PM2.5 readings during fall and winter months when temperature inversions trap pollutants near the surface. Wood burning, vehicle exhaust, and reduced wind speeds compound the effect. Residents with respiratory conditions should monitor forecasts closely between November and February.
AQI Trend (10 Years)
Air Quality Days by Year
North Liberty Median AQI by Year
Annual EPA air quality data for North Liberty — median AQI, day-category breakdown, and primary pollutant per year.
| Year | Median AQI | Good Days | Unhealthy Days | Max AQI | Primary Pollutant |
|---|---|---|---|---|---|
| 2025 | 44 | 172 | 7 | 127 | Ozone |
| 2024 | 45 | 237 | 2 | 119 | Ozone |
| 2023 | 51 | 175 | 13 | 223 | PM2.5 |
| 2022 | 52 | 167 | 6 | 122 | PM2.5 |
| 2021 | 52 | 169 | 1 | 105 | PM2.5 |
| 2020 | 47 | 207 | 5 | 166 | PM2.5 |
| 2019 | 46 | 217 | — | 100 | PM2.5 |
| 2018 | 51 | 173 | 7 | 133 | PM2.5 |
| 2017 | 44 | 236 | 4 | 133 | PM2.5 |
| 2016 | 51 | 182 | 8 | 119 | PM2.5 |
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 North Liberty Air Quality
What is the air quality in North Liberty today?
The current AQI in North Liberty is 13, 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 North Liberty getting better or worse?
Air quality in North Liberty has been improving. The median AQI has dropped 7 points (from 51 in 2016 to 44 in 2025), a positive trend for residents.
What is the most common air pollutant in North Liberty?
Ozone is the primary air pollutant in North Liberty, responsible for 160 days (59% 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 North Liberty have per year?
In 2025, North Liberty recorded 63% good air quality days (172 days) out of 273 monitored days. There were 7 Unhealthy for Sensitive Groups days and 0 Unhealthy days (AQI above 100). The highest single-day AQI recorded was 127.
What air quality grade does North Liberty receive?
North Liberty receives an air quality grade of A-, placing it better than 31% of US cities. This is based on a median AQI of 44 in 2025, with 172 good air quality days. The EPA monitors air quality in this area continuously using certified monitoring stations.
Air Quality Grade
Better than 31% of US cities
Nearby Cities
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National Rankings
See how North Liberty compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for North Liberty
Ozone is North Liberty's primary pollutant. Standard HEPA filters don't capture ozone molecules — you need activated carbon or PECO technology to chemically break them down. We highlight those units here.
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