PM2.5 vs Ozone: How the Two Main AQI Pollutants Differ
Nov 9, 2026
Fine particles and ground-level ozone both drive the Air Quality Index, but they form differently, peak at different times and come with different EPA health messages.
Latest
Air Quality Index (AQI) Explained: Categories, Colors and Ranges
Nov 9, 2026
What each AQI number and color means, which pollutants it covers, why the current reading on AirNow is a NowCast, and the health messages EPA attaches to each category.
Wildfire Smoke and Air Quality: How to Read AirNow’s Smoke Map
Nov 9, 2026
How the AirNow Fire and Smoke Map works, why monitors and sensors on the same street can disagree, and the smoke guidance EPA and CDC give, quoted with attribution.