Carbon Monoxide (also known as CO) is a colourless, odourless, poisonous gas and is a common yet preventable cause of death from poisoning worldwide. Approximately half of the deaths from unintentional CO poisonings result from the inhalation of smoke from fires. Other significant causes are vehicle exhausts and deaths in industrial/commercial settings.

The incomplete combustion of organic fossil fuels such as oil, gas or coal is a common environmental source of CO and is responsible for many cases of non-fatal, unintentional CO poisoning.

In normal conditions the combustion process (the addition of oxygen) will result in carbon in the fossil fuel, combining with oxygen, in the air, to produce Carbon Dioxide (CO2), the same substance we exhale when we breathe.

However, if there is a lack of air for the combustion process or the heating appliance is faulty, Carbon Monoxide can be produced.

When CO is inhaled into the body it combines with the blood, preventing it from absorbing oxygen. If a person is exposed to CO over a period, it can cause illness and even death.

Carbon Monoxide has no smell, taste or colour. This is why it is sometimes called the "Silent Killer".

Carbon Monoxide alarms can be used as a backup to provide a warning to householders in the event of a dangerous build-up of CO. Remember that Carbon Monoxide alarms are no substitute for regular inspection and maintenance of appliances, vents, flues and chimneys.