The air quality index measures PM2.5, less than 2.5 microns particles, to determine the intensity of air pollution in cities.

Complimentary Site Survey by Camfil Canada To help businesses achieve better air quality, Camfil Canada offers complimentary ...

Angelenos still bothered by the smell of smoke may be surprised to see that Air Quality Index numbers returned to “healthy” or “moderate” levels this week in L.A. County, but they shouldn ...

Learn what the air quality index (AQI) means, how it impacts your health, and how to stay safe when pollution is high.

Major air pollutants have declined in recent decades, but USA TODAY’s analysis shows wildfire smoke is taking their place.