Carbon Monoxide (CO)

CO fumes are silent, highly poisonous fumes produced by poorly maintained appliances and systems in the home. It is important to learn how to prevent CO in the home to protect health and life.


Carbon monoxide (CO) is known as a silent killer because you can’t taste, see or smell it yet the fumes are highly poisonous and cause around 50 deaths and hundreds of injuries every year.


Poisoning from CO can happen in a matter of minutes or over an extended period of time – it depends on the amount of CO in the air. The symptoms include:


  • Headaches


  • Dizziness


  • Nausea


  • Breathlessness


  • Collapsing


  • Losing consciousness


Here are some of the warning signs to look out for:


  • Symptoms only occur when you’re in your home and disappear or get better when you leave


  • Others in your home are experiencing similar symptoms (including your pets)


  • Black, sooty marks on the front covers of gas fires


  • Sooty or yellow/brown stains on or around boilers, stoves or fires


  • If you get any symptoms when appliances are in use, e.g. when the boiler is on


  • Increased condensation on the windows


  • Pilot lights frequently blowing out


  • Yellow instead of blue flames coming from gas appliances or the flames aren’t fully formed (e.g. if the flame isn’t all the way round on a gas hob burner).


What to do if you suspect CO poisoning:


  • Open doors and windows to ventilate and let fresh air in


  • If it’s safe to do so, switch the gas appliance off


  • Get outside into the fresh air as quickly as you can


  • Get medical advice – e.g. contact your GP or go to hospital and tell them you suspect CO poisoning


  • Before you return to your home it is very important to call the gas emergency number on 0800 111 999 and tell them what has happened


  • Let us know too by calling the Customer Hub on 0300 123 34567.


You can find more information about CO on the Health and Safety Executive website.


Did you know?


Long periods of significant exposure to carbon monoxide can cause serious complications, including brain damage and heart problems. In very severe cases, it can result in death.


Want to know more?


Read guidance on gas safety in the home here, the dangers and sources of carbon monoxide poisoning here.