Carbon monoxide

Carbon monoxide (CO) is a colorless, odorless, and tasteless flammable gas that is slightly less dense than air. It is toxic to s that use as an oxygen carrier (both  and ) when encountered in concentrations above about 35.

Carbon monoxide consists of one atom and one  atom, connected by a  that consists of two s as well as one  covalent bond.

Carbon monoxide is produced from the partial oxidation of -containing compounds; it forms when there is not enough oxygen to produce (CO2), such as when operating a  or an  in an enclosed space. In the presence of oxygen, including atmospheric concentrations, carbon monoxide burns with a blue flame, producing carbon dioxide.

is the most common type of fatal air poisoning in many countries. Carbon monoxide is colorless, odorless, and tasteless, but highly toxic. It combines with to produce, which usurps the space in hemoglobin that normally carries oxygen, but is ineffective for delivering oxygen to bodily tissues. Concentrations as low as 667 may cause up to 50% of the body's hemoglobin to convert to carboxyhemoglobin. A level of 50% carboxyhemoglobin may result in seizure, coma, and fatality. In the United States, the limits long-term workplace exposure levels above 50 ppm.

The most common symptoms of carbon monoxide poisoning may resemble other types of poisonings and infections, including symptoms such as, , , , , and a feeling of weakness. Affected families often believe they are victims of food poisoning. Infants may be irritable and feed poorly. Neurological signs include confusion, disorientation, visual disturbance, (fainting), and seizures.

Carbon monoxide detector
A carbon monoxide detector or CO detector is a device that detects the presence of the (CO) gas in order to prevent.

Elevated levels of CO can be dangerous to humans depending on the amount present and length of exposure. Smaller concentrations can be harmful over longer periods of time while increasing concentrations require diminishing exposure times to be harmful.

CO detectors are designed to measure CO levels over time and sound an alarm before dangerous levels of CO accumulate in an environment, giving people adequate warning to safely ventilate the area or evacuate. Some system-connected detectors also alert a monitoring service that can dispatch emergency services if necessary.

While CO detectors do not serve as smoke detectors and vice versa, dual smoke/CO detectors are also sold. Smoke detectors warn of smoldering or flaming fires by detecting the smoke they generate, whereas CO detectors detect and warn people about dangerous CO buildup caused, for example, by a malfunctioning fuel-burning device. In the home, some common sources of CO include open flames, space heaters, water heaters, blocked chimneys or running a car or grill inside a garage.