Smoke detectors are common household items. One type, ionization smoke detectors, uses a small radioactive source as a key component in detecting smoke particles. Photoelectric smoke detectors use a light and sensor to detect smoke. Ionization smoke detectors are more effective at detecting flash fires, while photoelectric smoke detectors are more effective in detecting smoldering fires. Both cost about the same, and many smoke detector models use both ionization and photoelectric features to achieve maximum detection.