Up to 1819 ft2, AeraSense technology, Removes 99.97% 0.3µm particles, Removes 99.9% bacteria & H1N1*
My Philips air purifier quality indication level does not change
The air quality sensor is dirty. Clean the quality sensor ( See " Clean the air quality sensor” in User Manual). There is not enough ventilation in the room. Open a window, to improve the air circulation.