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Carbon Monoxide (CO) - the silent killer

Carbon monoxide (CO) is an odourless, colourless, non-irritant gas. It is the most common cause of fatal poisoning in Britain today. It causes the accidental deaths of up to 500 people each year in the USA and a much larger number of sub-lethal poisonings.

Carbon monoxide is produced by the incomplete combustion of carbon-containing fuels, such as gas (domestic or bottled), coal, oil, coke and wood. Gas stoves, fires, heating boilers, gas-powered water heaters, paraffin heaters, and solid fuel-powered water heaters are all potential sources of carbon monoxide. The problem arises when such appliances are poorly maintained, not serviced and housed in poorly ventilated areas. Waste products of combustion are not effectively removed, for example because of blocked flues and chimneys, then poisonous gas mixtures may re-enter the room.

Therefore you must regularly sweep your fire, ensure there is adequate ventilation and always use the right fuel.

What are the symptoms of carbon monoxide poisoning?

One of the difficulties with diagnosing carbon monoxide poisoning is that many of its symptoms are similar to those of other conditions. Often the onset of symptoms is gradual, occurring without the individual being fully aware of what is happening. Coupled with this is the fact that the severity of the poisoning depends on:

  • how much carbon monoxide is actually present in the environment.

  • the duration you are exposed to carbon monoxide.

  • the age of the individual concerned – elderly, children and the foetus are all at greater risk.

  • the general state of health.

  • the extent of physical activity – effects are increased with higher activity levels.


The commonest symptoms (with frequency of occurrence in brackets) include:

  • headache (90 per cent)

  • nausea and vomiting (50 per cent)

  • vertigo (50 per cent)

  • altering states of consciousness (30 per cent)

  • weakness (20 per cent).

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