In a house fire, are you safer sleeping with your bedroom doors open or closed? See the video on the right for the dramatic, life-saving difference a door can make. Smoke Detectors: The two primary types of smoke detectors are ionization and photoelectric, which use different technologies to detect specific kinds of fires. For the best protection, experts from the National Fire Protection Association (NFPA) recommend using dual-sensor units that combine both technologies. Core Sensing Technologies: Ionization Detectors: These use a small amount of radioactive material to ionize air in a sensing chamber. They are generally more responsive to fast-flaming fires (e.g., paper or