PM2.5 is a scale for measuring real time air quality. Its values vary from 0 to 500. 
The PM2.5 indication is connected to your Philips Air Purifier’s air quality light ring/bar to inform you in real time about the quality of the ambient air.
The different colors indicate the following: 
* Blue: good 
* Blue-Violet: fair 
* Red-Purple: unhealthy 
* Red: very unhealthy
 What does the PM2.5 indicator in my Philips Air Purifier mean?
Published on 28 June 2023