Which type of smoke detector reacts faster to smoke? The two most common types are ionizing and photoelectric. They use different methods to sense smoke particles in the air. You place a lit cigarette at five distances from each detector: 200mm, 400mm, 600mm, 800mm, and 1000mm. Then you time how many seconds each detector takes to trigger its alarm. The ionizing detector triggered faster at every distance. At 200mm it fired in 6 seconds vs. 8 for the photoelectric. At 1000mm the gap was 46 seconds vs. 55.