Carbon Monoxide Poisoning

Carbon monoxide (CO) gas is created by the incomplete burning of fuel.  It is a poisonous gas and breathing in just a small amount can cause loss of consciousness and death.  More than 50 people in the UK die from accidental carbon monoxide poisoning each year and over 200 people are injured seriously.

Carbon monoxide has no smell, taste or colour.  This makes it hard to detect and also means that it is easy to inhale without realising you are doing so.

Carbon monoxide is made when fuels such as oil, gas, wood and coal fail to burn fully.  The oxygen in the room is gradually used up and replaced with carbon dioxide when a fire burns in an enclosed room.  After a build-up of carbon dioxide in the air, the fuel is stopped from fully burning and it begins to release carbon monoxide.

Symptoms of Carbon Monoxide Poisoning
The most common symptom of carbon monoxide poisoning is a headache.  Other common symptoms are:

nausea and dizziness
tiredness and confusion
stomach pain and being sick
difficulty breathing and shortness of breath

The symptoms of carbon monoxide poisoning can be similar to those of flu and food poisoning.  However, it does not cause a fever, unlike flu.

You might notice that your symptoms are not as bad at times when you are away from the source of the carbon monoxide.

Your symptoms will get worse the longer your breathe in carbon monoxide gas.  You might lose your vision, balance and memory and eventually you may lose consciousness.  If there is a lot of carbon monoxide in the air, this can happen within two hours.  However, sometimes the symptoms of carbon monoxide poisoning can happen a number of days or even months after breathing in the carbon monoxide.

The symptoms of carbon monoxide poisoning  which develop later include:

memory loss
confusion
c-ordination problems

The symptoms of carbon monoxide poisoning can be a lot more severe if you have breathed in high levels of carbon monoxide and can include:

vertigo – the sensation that you or the environment around you, are spinning
intoxication – the effects of poisoning, e.g. an impaired mental state and changes to personality
breathlessness and tachycardia – a heart rate or over 100 beats a minute
ataxia – a loss of physical co-ordination caused by underlying damage to the nervous system and brain
chest pain due to heart attack or angina
seizures- muscle twitches, tongue biting and total body shaking caused by an uncontrollable burst of electrical activity in the brain
loss of consciousness – death may occur within a few minutes in cases where there ate very high levels of carbon monoxide

Causes of Carbon Monoxide Poisoning
Gas, oil wood and coal are fuel sources which many household appliances use:

gas fires
open fires
boilers
central heating systems
water heaters
cookers

Carbon monoxide gas is produced if the fuel in these appliance fails to burn fully.  Running cars, burning charcoal and smoking cigarettes also causes the production of carbon monoxide gas.

Here the main causes of carbon monoxide poisoning are outlined.

Poorly Installed or Maintained Appliances
The main causes of accidental exposure to carbon monoxide are incorrectly installed and badly maintained household appliances, such as heating and cooking devices.

Household appliances should produce very little carbon monoxide gas provided that they are fitted correctly, used safely and well maintained. 

Blocked Flues and Chimneys
Another potential cause of carbon monoxide poisoning are blocked flues and chimneys because they can prevent carbon monoxide gas from escaping and therefore allow it to build up to dangerous levels in a room.

Enclosed or Unventilated Spaces
The risk of carbon monoxide poisoning is increased by burning fuel in an enclosed or unventilated space, where there are no air vents, windows or doors left open or ajar.  Examples of these would be a car engine which is left running inside a garage or a faulty heating boiler in a poorly ventilated kitchen. 

Paint Fumes
Fumes from paint removers and cleaning fluids which contain methylene chloride can also cause carbon monoxide poisoning.  Methylene chloride is converted into carbon monoxide when it is inhaled.

Diagnosis of Carbon Monoxide Poisoning
Diagnosis of carbon monoxide poisoning can be done by you GP based on a combination of your physical symptoms and the environment around you.

A blood sample will be taken if you have the symptoms of carbon monoxide poisoning.  Your blood will be checked for carboxyhaemoglobin and if there is a level of 30%, this indicates severe exposure.

An electrocardiogram (ECG) might also be done to check how well you heart is pumping blood around your body.

It is important that you are aware of the dangers of carbon monoxide poisoning and that you look out for the warning signs.

As well as the symptoms explained earlier, the following situations may also be signs of carbon monoxide poisoning:

other people in your house, flat, workplace etc have similar symptoms
your symptoms go away when you go away on holiday and come back when you return
your symptoms tend to be seasonal, e.g. you have more headaches in the winter time when the central heating is used more often.

Other possible signs to look out for are:

sooty marks on the wall around stoves, boilers or fires
sooty marks on the front cover of gas fires
smoke building up in rooms due to faulty flues
yellow rather than blue flames coming from gas appliances

If you or anyone else in your home or workplace develops flu-like symptoms with no temperature and you think it may be linked to a carbon monoxide leak you should:

stop using all the cooking and heating appliances which use fuel rather than electricity
open all of the windows
call the Health and Safety Executive Gas Safety Advice Line for advice.  0800 300 363
visit your GP as soon as you can

If you have a carbon monoxide leak you should make sure that a suitable qualified engineer inspects your cooking appliances and central heating and water appliances.

Treatment for Carbon Monoxide Poisoning
If you think that you have carbon monoxide poisoning you should move away from the possible source of the gas so your symptoms can be assessed.

You should consult your GP straightaway.  You will probably not need to go to hospital if you have mild poisoning but it is still important that you seek medical advice.

You will be treated in hospital if you have been exposed to a high amount of carbon monoxide poisoning and given 100% oxygen through a tight fitting mask.  Breathing in concentrated oxygen allows your body to replace carboxyhaemoglobin more quickly.  You will carry on oxygen therapy until the levels of carboxyhaemoglobin decrease to a level below 10%.

Hyperbaric oxygen therapy (HBOT) is a treatment which floods the body with pure oxygen and helps it to overcome the oxygen shortage that carbon monoxide poisoning causes.

Currently there is insufficient evidence with regards to the long-term effectiveness of HBOT for treating severe cases of carbon monoxide poisoning.  Therefore, standard oxygen therapy is typically the treatment option.

In certain situations however, HBOT might be recommended.  It may be used in cases of extensive carbon monoxide exposure and if there is suspected nerve damage.  The decision to carry out this treatment is decided on a case by case basis.