There are two types of popular smoke alarms: Ion (ionization) and Photo (photoelectric). Both must pass fire tests before entering the market and both are designed to provide consumers with warning in the case of a fire.
The differences between the two types of smoke alarms lie in the methods used to detect smoke. The Ion smoke alarms react to changes in ionized particles and are more sensitive to flaming fires whereas the Photo smoke alarms react to how smoke affects light and are more sensitive to smoldering fires.
It is impossible to determine which smoke alarm is better because they are designed to respond to different triggers which depend on what starts the fire and what burns. Consider installing both types of alarms or dual sensor smoke alarms on every level of your home and near every sleeping area.
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