American Sensors(TM) carbon monoxide alarms sample the air for carbon monoxide every 1 to 3 minutes. When a unit detects a certain pre-programmed level of carbon monoxide, the alarm's microprocessor will store this information and measure the carbon monoxide level against time. If the carbon monoxide level is low or is present only for a short time, the alarm will ignore it and burn the sensor clean (so the sensor does not accumulate carbon monoxide and cause the unit to nuisance alarm). However, if the carbon monoxide level is high or if a low carbon monoxide level remains for a pre-programmed period of time, the alarm will sound either a low level warning or a hazard level alarm depending on the degree of the carbon monoxide condition. This programming effectively minizizes the occurrence of nuisance alarms.