Carbon monoxide is an extremely poisonous gas. Inhaling it in a confined space can be lethal, and since it is has no odour or colour, it is very dangerous.
It is produced during combustion when there are not enough oxygen molecules around the hydrocarbon molecules. This can be caused by an incorrect air-fuel ratio.
In modern vehicles, carbon monoxide emissions have been reduced by better engine designs, and by chemically treating the exhaust gas.
Carbon monoxide, is a colourless, odourless, flammable and highly toxic gas. It is a major product of the incomplete combustion of carbon and carbon-containing compounds.Sources
Carbon monoxide has many common sources. The exhaust of the internal combustion engine, when burning a carbon-based fuel (i.e. almost any fuel except pure hydrogen) contains carbon monoxide, especially when the temperature is too low to effect complete oxidation of the hydrocarbons in the fuel to water and CO2, because the time (i.e., the residence time) available in the combustion chamber is too short, or because there is insufficient oxygen present. Usually, it is more difficult to design and operate a combustor for very low CO than for very low unburned hydrocarbons. Carbon monoxide is also present in small but significant concentrations in cigarette smoke.
Toxicity
CO binds very strongly to the iron atoms in hemoglobin, the principal oxygen-carrying compound in blood. The affinity between CO and hemoglobin is 200 times stronger than the affinity between hemoglobin and oxygen. As CO binds to the hemoglobin, it cannot be released nearly as readily as oxygen would be. Thus, the body's hemoglobin becomes saturated with CO and is rendered incapable of carrying oxygen to the body. A sufficient exposure to carbon monoxide can reduce the amount of oxygen taken up by the brain to the point that the victim becomes unconscious, and can suffer brain damage or even death from anoxia. Hemoglobin acquires a bright red colour when bound to carbon monoxide, so a casualty of CO poisoning can actually look abnormally pink-cheeked and healthy.
First aid for carbon monoxide poisoning is to immediately remove the victim from the exposure without endangering oneself, call for help, apply CPR and if possible apply oxygen first aid. Hyperbaric oxygen therapy is a treatment for carbon monoxide poisoning.
Source: CDX Global & Wikipedia - en.wikipedia.org
