Carbon dioxide detectors, also known as CO alarms, detect harmful carbon monoxide gas in the air and trigger an audible alert to warn you of its presence. They are essential to protect you and your family from the poisonous gas, which is colorless, odorless, and tasteless. Carbon monoxide is produced by furnaces, water heaters, stoves, furnaces, and other appliances that burn fuel. It can also enter your home from leaking air ducts, or due to insufficient indoor ventilation. Exposure to high levels of the gas can lead to headaches, dizziness, tiredness, or asphyxiation.

The most common CO detectors use an electrochemical cell with a liquid-filled tube, two electrodes, connection wires and an electrolyte such as sulfuric acid. One of the electrodes oxidizes the carbon monoxide into carbon dioxide and the other consumes oxygen, producing an electric current proportional to the amount of gas detected near the sensor.

Breathing Easy: The Role of Carbon Dioxide Detectors in Indoor Air Quality

Other CO detectors use an infrared light sensor that measures the concentration of carbon monoxide in a sample of air. The gas molecules absorb a specific wavelength of infrared light while allowing other wavelengths to pass through, which the sensor then detects and relays to the alarming device.

Regardless of the technology used to detect CO2, all CO alarms must conform to minimum sensitivity and alarm characteristics outlined by Underwriters Laboratory in the Standard for Carbon Monoxide Detectors, UL 2034. They must also have a test button to confirm the proper operation of the battery, circuit, and buzzer. Some models even display a digital readout of the prevailing carbon monoxide concentration in parts per million.