St. John, Indiana Air Quality
St. John has a median AQI of 53, earning an air quality grade of B — good air quality that ranks better than 8% of US cities. Air quality has remained relatively stable over the past decade. Particulate matter (PM2.5) is the primary concern, often linked to vehicle traffic, industrial activity, and wildfire smoke. In 2025, St. John recorded 106 good air quality days (39% of monitored days) and 14 unhealthy days.
Population: 22,567 • County: Lake
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Quick Facts
| Current AQI | 16 — Good |
| Air Quality Grade | B |
| Median AQI (2025) | 53 |
| vs. U.S. Cities | Better than 8% |
| Primary Pollutant | PM2.5 |
| Unhealthy Days/Year | 14 |
| 10-Year Trend | → Stable |
| Data Source | EPA AirNow |
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 30 Days
Current Pollutant Levels
Real-time data from EPA AirNow
AQI Trend (10 Years)
Air Quality Days by Year
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 St. John Air Quality
What is the air quality in St. John today?
The current AQI in St. John is 16, which is rated "Good". Air quality is satisfactory, and air pollution poses little or no risk.
Is air quality in St. John getting better or worse?
Air quality in St. John has remained relatively stable over the past decade, with a median AQI of around 53.
What is the most common air pollutant in St. John?
PM2.5 is the primary air pollutant in St. John, responsible for the most air quality-impacted days in 2025. Particulate matter can originate from vehicle exhaust, wildfires, and industrial emissions.
How many unhealthy air days does St. John have per year?
In 2025, St. John had 14 days when air quality was unhealthy or unhealthy for sensitive groups (AQI above 100). There were 106 good days and 152 moderate days out of 273 days monitored.
What air quality grade does St. John receive?
St. John receives an air quality grade of B, placing it better than 8% of US cities. This grade is based on a median AQI of 53 for 2025, derived from EPA monitoring data.
Air Quality Grade
Better than 8% of US cities
Nearby Cities
Protect Your Health
With a median AQI of 53, indoor air purification is recommended
See Recommended Purifiers ↓Get AQI Alerts
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National Rankings
See how St. John compares to every other US city by air quality.
Best Air Quality Cities →All city rankingsRecommended Air Purifiers for St. John
Based on your area's air quality (median AQI: 53), we recommend these air purifiers to help protect your health indoors.
Honeywell HPA300
Powerful workhorse for large rooms. Built to last.
- ✓Perfect room size match
- ✓Recommended for your air quality
- ✓Has 1/3 desired features
- ✓High performance
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Other Great Options
Blueair Blue Pure 211+
High performance for large rooms with simple operation.
Dyson Pure Cool TP04
Premium all-in-one air purifier and fan with advanced features.
Molekule Air Pro
Commercial-grade with patented PECO technology for destroying pollutants.
Not sure which air purifier is right for you?
Learn more about different types of air purifiers and how to choose the best one for your needs.
Read our complete buying guide →