carbon monoxide poisoning – the silent killer

what is it?

Jessica from Hollyoaks
©Channel 4

Carbon monoxide – or 'CO' – is an odourless, colourless, non-irritant gas created from the incomplete combustion of gas or fuel. Common sources include faulty central heating systems, gas appliances and fires. Blocked flues and chimneys mean the gas can't escape and is inhaled by the unsuspecting individual. Car exhausts are also a common source – a lethal level of carbon monoxide in the blood can develop in just ten minutes inside a closed garage.

how dangerous is it?

It's the most common cause of fatal poisoning in Britain today, responsible for the accidental deaths of up to 50 people each year in the UK and an estimated 200 sub-lethal poisonings. However, these figures could be just the tip of the iceberg for two main reasons: firstly, there's generally little awareness of carbon monoxide poisoning among both the general public and the medical profession; and the signs and symptoms associated with carbon monoxide poisoning often mimic many other conditions.

who's most at risk?

Children, pregnant women, babies, and anyone with a heart condition, but CO poisoning can affect anyone.

How is CO formed?

When any fire burns it uses up oxygen to create carbon dioxide – if the amount of oxygen decreases (because the fire's in an enclosed space and is using up the limited oxygen as it burns) it can lead to the incomplete combustion of the fuel, creating CO. So, even perfectly designed and maintained heating appliances will eventually begin producing dangerous amounts of CO if used in confined and poorly ventilated areas. Having poorly operating appliances, only makes the problem worse more quickly.

How does it cause poisoning?

The CO bonds with the haemoglobin in the blood that's normally responsible for carrying oxygen around your body – so the tissues and organs in your body are starved of oxygen. This can also cause blood vessels to become 'leaky', something that's especially seen in the brain, causing swelling which can result in unconsciousness and neurological damage.

What are the symptoms?

These vary hugely according to your age and health, how much you've breathed in and how long you've been exposed to the gas. The symptoms are usually very gradual and often occur without the victim being aware of what's happening, as the brain's starved of oxygen. The most common symptoms are similar to those of viral cold infections: headache, nausea, dizziness, sore throat and dry cough. In children, the symptoms are similar to those of a stomach upset, with nausea and vomiting. More severe poisoning can result in a fast and irregular heart rate, over-breathing (hyperventilation), confusion, drowsiness and difficulty breathing. Seizures and loss of consciousness may also occur. Note: symptoms can also occur a few days or even months later, including confusion, loss of memory and problems with coordination.

Clues that point towards a problem within the home or office include:

• more than one person is affected
• symptoms appear or get worse when gas appliances are in use
• symptoms are worse in the winter when gas boilers/heaters are in use
• symptoms improve when family members are not at home, but recur on their return.

How is it diagnosed?

Individuals can either be exposed to high levels of carbon monoxide over a relatively short period of time (acute exposure) or, more commonly, to lower levels of exposure over a longer period of time (chronic exposure). Acute exposure's easier to diagnose as the symptoms are more pronounced, but it's the more common chronic exposure symptoms that are more subtle and difficult to tell apart from other conditions. If you suspect anything, see your GP to arrange a blood or breath test.

How is it treated?

First, move the affected individual(s) away from the CO source. If they're only mildly affected, they should seek medical attention, but probably don't need to be immediately rushed to hospital. Hospital treatment involves administering pure oxygen in a sealed pressure chamber to push the CO out of their system.

What can you do to prevent it?

Firstly by being aware of its causes and symptoms and making sure everyone you live and work with is too. Get all appliances professionally installed and regularly inspected; ensure adequate ventilation for all fuel-burning appliances by getting chimneys and flues checked; and install CO alarms, available from all good DIY stores (check for the BSI standard BS EN 50291 to make sure it's up to the job).

What do you do if the alarm sounds?

If your alarm goes off and you have a detector that displays the amount of carbon monoxide detected, make a mental note of what the reading states. Pick up the instruction manual but take it outside the house to read it.

Check whether you or any other family member is affected by any of the signs and symptoms of carbon monoxide poisoning (headache, dizziness, nausea, fatigue). If carbon monoxide poisoning symptoms are suspected, everyone should vacate the house and dial 999 for an ambulance if necessary. If no one has any symptoms of poisoning, promptly turn off all gas or other fuel burning appliances and ventilate the whole house by opening all windows and doors. Contact a professional appliance specialist, e.g. British Gas or other CORGI (Council of Registered Gas Installers) registered gas specialists, to check your appliances.

find out more

Carbon Monoxide Kills
www.carbonmonoxidekills.com/
Facts on carbon monoxide (CO) poisoning prevention including the use of CO monitors in the home.

CO Awareness
www.co-awareness.org
Support victims poisoned by carbon monoxide poison, their families and friends.

CORGI
www.trustcorgi.com
The UK's gas safety watchdog with indepth information on gas safety.

Health and Safety Executive (HSE)
www.hse.gov.uk/gas/domestic
The Health and Safety Executive's domestic gas safety website.

Health and Safety Executive (HSE) Gas Safety Advice Line
Tel: 0800 300 363
Provides free guidance and information to people on gas safety matters.

NHS Direct
www.nhsdirect.nhs.uk/articles/article.aspx?articleId=417
Provides medical information on carbon monoxide poisoning.

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(October 2007)