Carbon monoxide poisoning: symptoms, signs & protection

Carbon monoxide (CO) is an odourless and tasteless gas that is invisible to the naked eye. It is formed by hydrocarbon combustion and exposure to it can be fatal. Every year there are around 25 deaths from accidental carbon monoxide poisoning in England and Wales (Source: NHS). It is important to ensure that all central heating work in your home is conducted by a Gas Safe registered engineer to help prevent you and your family from being exposed to carbon monoxide.

What is carbon monoxide?

Formed naturally when a compound containing carbon burns incompletely, carbon monoxide is created due to a lack of oxygen.

Most commonly, carbon monoxide leakage can be found in homes with poorly fitted gas appliances, such as gas fires and cookers, and faulty central heating systems. It could also occur where appliances are badly repaired or poorly maintained. You may also find carbon monoxide if flues, chimneys or vents are blocked.

Carbon monoxide leaks are very serious. Anyone is at risk, even your pets. Because leaks are hard to detect, it’s important that you are aware of the symptoms and the ways you could help prevent them from occurring.


What are the symptoms of carbon monoxide poisoning?

Here are different signs to look out for, depending upon the level of exposure.

Mild exposure - You may feel slightly ill and experience headaches, nausea and vomiting. These non-specific symptoms may be misdiagnosed as flu, gastroenteritis or food poisoning.


Moderate exposure - You might start to feel weak, dizzy and unsteady, and have problems with concentration. As confusion develops, your behaviour might change, accompanied by shortness of breath and chest pains.


Severe exposure – This could affect you rapidly; seizures, comas and fatalities have been reported.


Because it is easy to mistake the symptoms of carbon monoxide poisoning with other illnesses, other indicators include:


  • Experiencing the symptoms most severely at home and less so when you are away
  • When others in the house – including pets – are experiencing the same symptoms at the same time


After exposure to carbon monoxide, you might experience long-term problems, including difficulties with memory, mood and behaviour. Your language and cognition may also be affected. Damage to the brain (specifically the basal ganglia) could cause problems with movement, (sometimes likened to Parkinson’s disease). The deteriorating effects of acute carbon monoxide poisoning can be delayed from a few days to as long as five or six weeks (Source: (Source: Headway).


If you suspect a gas leak, call the National Gas Emergency Service number on 0800 111999 immediately.

How can you protect yourself from carbon monoxide poisoning?


You could ensure your home is Gas Safe by following these five simple rules:


  • Always use a Gas Safe registered engineer – Gas Safe registered engineers are legally permitted to carry out gas work and will carry a Gas Safe ID card.
  • Ensure your boiler and other gas appliances are serviced annually – this could help to keep your appliances in good working condition.
  • Ensure your appliances are fully ventilated – This could help to prevent an accumulation of gases.
  • Check that the flame in your boiler is a strong, clear blue – a yellow or orange flame could indicate incomplete combustion and therefore highlight a risk of carbon monoxide.
  • Install a carbon monoxide alarm that meets British or European Standards – Many homeowners get these excellent early warning systems installed to reduce the risk of carbon monoxide poisoning in the home.

Carbon Monoxide Detectors


Place your carbon monoxide (CO) detectors in a safe and suitable location. You are advised by the Consumer Product Safety Commission (CPSC) to place the device near your sleeping area, where it could alert you when you are asleep. For added protection, it is also recommended for detectors to be placed on every level and in every bedroom, as this potentially enables any sign of carbon monoxide to be picked up sooner (CPSC).


Unlike smoke detectors, carbon monoxide detectors should usually be placed at knee level because carbon monoxide mixes with the air rather than rises. It’s typically recommended not to install carbon monoxide detectors within fifteen feet of heating or cooking appliances, as these appliances may emit a degree of carbon monoxide upon start-up, causing an unnecessary alert. Also avoid significantly humid areas such as bathrooms (CPSC).


The information provided is not a substitute for professional or medical advice and is intended to bring awareness to consumers. The information should not be relied upon to diagnose Carbon Monoxide related conditions and you should always seek professional medical assistance and advice where required.

Information and other materials on this website are not intended to constitute professional advice and should not be relied upon. Please see our Terms of Use for further details.

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