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Carbon Monoxide Facts

Find out all the things you need to know about carbon monoxide and its dangers.

What is carbon monoxide?

Carbon monoxide (CO) is a poisonous gas which is emitted from appliances which run on carbon-based fuels.  Unlike like other gases, carbon monoxide is odourless and colourless.

Does carbon monoxide gas smell?

Gas is naturally odourless, so gas companies add a distinct smell to act as a warning should there be a gas leak.

Where does CO come from?

Carbon monoxide is produced when fuels burn without sufficient air or ventilation.  It can also be produced by appliances which are faulty or have been poorly fitted.  

If you have an oil, gas or wood-burning appliance, you need to have a carbon monoxide detector fitted. 

How much CO is enough to harm someone?

CO is highly dangerous. Even low exposure can be fatal.  Less than 2% is enough to kill someone in just 1-3 minutes.

What does CO do to the body?

Carbon monoxide starves the body of oxygen, severely affecting the nervous and respiratory system. Blood cells and vital organs such as the heart and lungs are deprived of oxygen which can cause cardiovascular problems or lung disease.

What are the symptoms of carbon monoxide poisoning?

Symptoms of CO poisoning can include:

  • Headaches
  • Nausea
  • Vomiting 
  • Breathlessness 
  • Dizziness
  • Flu-like symptoms 

If you or anyone else are experiencing these symptoms, seek medical advice immediately.

How many people die from CO every year? Every year 50 people die from CO poisoning, and a further 4,000 are admitted to A&E after exposure.



What should I do if I think I have a gas leak?

If you think there may be a gas leak in your property:

  • Open all the doors and windows to get fresh air immediately 
  • Turn off any gas appliances 
  • Leave the house
  • Call the Gas Emergency Helpline on 0800 111 999
  • Seek medical attention immediately and inform them that you suspect carbon monoxide poisoning


How often should I check my appliances?

Your appliances should be checked every year or when you move into a new property.  These must be checked by a Gas Safe registered engineer.


What is the Gas Safe Register?

The Gas Safe Register is the official body of qualified gas engineers in the UK,which ensures that the public is protected from unsafe gas work.  You can ensure that your gas engineer is on the Gas Safe Register by checking their identity card.


What are the warning signs?

Any of the following could show signs of carbon monoxide:

  • Flames on a cooker should be crisp and blue.  If they are yellow, hazy and flickering then you need to get your cooker checked
  • Dark staining on or around appliances
  • Increased condensation around windows 
  • Pilot lights that frequently blow out 


How can I prevent CO poisoning?

There are steps you can take to keep your house safe and prevent CO poisoning:

  • Install a carbon monoxide detector in your home, Gas Safe strongly recommends installing an audible one
  • Have any gas, oil or coal-burning appliances annually serviced by a Gas Safe registered engineer 
  • Make sure your appliances are vented properly. Vents should go up slightly as they go outdoors 
  • Never try to mend a broken vent with tape. Always get help from a registered engineer
  • Never use an oven to heat your home, or burn charcoal indoors. Both can cause a build-up of CO in your home