Though you can neither see it, smell it nor taste it, carbon monoxide (CO) is
an extremely poisonous gas. In fact, over 50 people die from CO poisoning each year in the UK.
Carbon monoxide is a by-product of the incomplete combustion of carbon-based fuels, like coal. Since energy is released when a fuel reacts with oxygen, in order to perform most efficiently, a fossil fuel must have a rich air supply. When the fuel is burned with sufficient oxygen complete combustion will occur, producing carbon dioxide and water. However, when a hydrocarbon fuel is burned with only a limited air supply, incomplete combustion will occur, producing carbon (in the form of soot), water and toxic carbon monoxide gas.