AIR-Intelligence HSSD continuously adapt their sensitivity to the environment in which they are installed, providing alarm thresholds which are 'relative' to the background particle levels in the protected area, instead of placing the alarm threshold at a fixed level relative to ambient conditions. At any time, the detector's performance remains constant, regardless of fluctuations in the normal background particle level. AIR-Intelligence detectors only respond to particle levels significantly above the expected background level, such as from a genuine fire situation.