The LED strip around the top of the unit indicate the amount of particulate matter recorded by the machine as the air is passed through the unit.
The values detected by the unit will reflect in different LED colours, as shown below:
Blue (Very Good) 1 - 35µg/m³
Green (Good) 36 - 75µg/m³
Amber (Bad) 76 - 150µg/m³
Red (Very Bad) 151 - 500µg/m³
Rediair will continually monitor the air quality and the LED will change accordingly as matter is removed from the air.