We were asked to consider the relative merits and safety of the two main types of smoke detectors: ionization or photoelectric. Some say that ionization smoke detectors are prone to so many false alarms that users turn them off and they are therefore not as safe as photoelectric detectors. Others argue that their very sensitivity to flaming fires is what makes ionization detectors desirable. We decided to ask the experts. We queried the U.S. Fire Administration, National Fire Protection Association, International Association of Fire Chiefs, U.S. Consumer Product Safety Commission, National Volunteer Fire Council, National Council on Radiation Protection and Consumer Reports. Bottom line: because ionization and photoelectric smoke detectors can each sense distinctly different, yet potentially fatal fires, and because no one can predict what type of fire might start in a home, it is recommended that every residence and place where people sleep be equipped with both ionization AND photoelectric smoke alarms, OR dual-sensor smoke alarms, which contain both ionization and photoelectric smoke sensors. See our article for complete details.