The public awareness of the hazards of dangerous concentrations of carbon monoxide or other toxic gas in the air has greatly increased in recent years. Carbon monoxide remains a significant cause of human fatality because of its colorless and odorless characteristics. Carbon monoxide poisoning deprives the brain of oxygen which can cause slight to severe incapacitation and even death. Carbon monoxide affects people primarily by binding to hemoglobin in the blood, thereby preventing the normal transportation of oxygen to the tissues. Oxygen is normally transported to the tissues in the body by reversibly binding with hemoglobin present in red blood cells as blood circulates through the lungs. Carbon monoxide on the other hand diffuses rapidly into the blood and attaches to the hemoglobin, which has a great affinity for CO. As the blood moves through the body, the hemoglobin releases the oxygen for use in the body tissues. The blood then returns to the lungs, where oxygen again binds to the hemoglobin and the process repeats itself. When carbon monoxide is inhaled, it combines with oxygen-carrying hemoglobin of the blood to form carboxyhemoglobin. Once combined with the hemoglobin, the hemoglobin is no longer available for transporting oxygen. The amount of carboxyhemoglobin that builds up is a factor of the concentration of the gas being inhaled and the duration of the exposure. Carbon monoxide can act in the body in high concentrations, or slowly over a long period of time. The symptoms of carbon monoxide exposure are similar to those of influenza and include nausea and headache. At high concentration levels, carbon monoxide quickly physically incapacitates a person. After physical incapacity sets in, the exposed person has about 20 minutes to live if he remains in the presence of carbon monoxide. Because it takes several hours to remove carbon monoxide from the body of a person, concentrations of carbon monoxide can gradually build up in the blood causing headaches, fatigue, dizziness, nausea, burning eyes, or unconsciousness.

Carbon monoxide detection is important for health and safety concerns of human breathing. The detection of carbon monoxide at the initial stage of a fire, could result in quick notification to a person in the area which could result in the saving of lives and the minimizing of property loss. Devices for sensing carbon monoxide and triggering an alarm in the presence of excess concentrations of carbon monoxide are widely available. Public awareness of the dangers posed by carbon monoxide in the home and continuing advances in carbon monoxide detection technology and reliability has greatly increased the number of carbon monoxide detectors installed in homes, various industrial and commercial sites. Carbon monoxide detectors can be broadly classified into one of different types according to the gas sensitive element employed. The electrochemical and spectroscopic detectors offer rapid response times, high resolution and high accuracy, but are expensive and not suitable for domestic use. Typical electrochemical technology uses three platinum electrodes in an electrolyte solution that generate energy when they react with the carbon monoxide, thereby setting off the alarm. Chemical sensors are inexpensive devices that are usually based on palladium or iodine salts which exhibit a color change upon exposure to CO. Carbon monoxide is known to absorb infrared radiation. Carbon monoxide detectors have taken advantage of this phenomenon to determine the differences between infrared radiation absorption in a test cell containing a gas to be tested and a reference cell containing a fixed composition of gas. However, infra-red detectors of CO are expensive and bulky, requiring a long path length, heated IR sources, and expensive detectors. The electrochemical detectors may be preferred to the semiconductor sensors because the semiconductor must be heated and therefore utilize significant power which limits battery life or requires drawing current from the residential power line. Electrochemical carbon monoxide sensors are capable of sensing a number of gases in addition to carbon monoxide. These gases include hydrogen, sulfur dioxide, and nitrogen oxides. Carbon monoxide detectors are typically mounted at various strategic locations around a house or building to detect dangerous air quality conditions as a result of such things as a fire or a smoke or carbon monoxide producing event.