Abstract: Hazard detectors are shown and described. Included are devices, systems, kits, and methods for a hazard detector. A hazard detector may in some embodiments include a housing, a presence detector, a hazard detector and a control system. In some examples, hazard detector systems may include a hazard detector having one or more sensors with the ability to detect a hazard and a system for evaluating the hazard for characteristics prior to signaling an alarm. A hazard detector may include power saving systems for longevity and reliability of the detector.