Carbon monoxide (CO) is a poisonous gas produced when fossil fuels like gas, coal, oil or wood are burnt where there's not enough oxygen. Faulty appliances can give off carbon monoxide, which can build up in your home when there's poor ventilation.

Carbon monoxide is colourless, odourless and can be fatal.

The warning signs

You can't taste, smell or see carbon monoxide. But it's easy to spot signs that your gas or heating appliances could be producing it.

Danger signs can include:

  • Soft yellow flames
  • Sooty stains or discolouration on or around gas appliances
  • Increased levels of condensation in rooms with gas appliances
  • Fumes or smoke in the house
  • Slower than usual burning of solid fuel fires

Recognising carbon monoxide poisoning

Recognising the early symptoms of carbon monoxide poisoning saves lives.

The symptoms are similar to the flu and include:

  • Headaches
  • Drowsiness
  • Visual problems
  • Dry throat
  • Nausea
  • Vomiting

If you experience these symptoms, but feel better when you're outside or away from your home, it's possible that you're suffering from carbon monoxide poisoning.

What to do if you detect possible carbon monoxide

If you think that there may be carbon monoxide in your home, there are some steps to take to prevent it affecting your health:

  • Open all your doors and windows to ventilate the house.
  • Phone the National Gas Emergency Service on 0800 111 999.
  • Switch off your gas supply at the mains control valve. You do this by pulling the handle 90 degrees, so that it's at a right angle to the pipe.
  • Make sure the faulty appliance is switched off. Don't use it again until a Gas Safe Register™ engineer has inspected or repaired it.

If you or someone you're with is feeling ill, visit your doctor urgently. Explain that symptoms may be related to CO poisoning and ask that they test a blood or breath sample.

If someone is seriously ill from poisoning it's vital that they leave the room and get fresh air. You should call for medical help urgently. Make sure that when help arrives you tell them that you suspect carbon monoxide poisoning. This will ensure they get the appropriate treatment quickly.

How to prevent poisoning

There are some simple things you can do to prevent carbon monoxide poisoning:

  • Make sure your gas appliances are serviced regularly by a Gas Safe Register™ engineer
  • Buy an audible carbon monoxide detector
  • Ensure chimneys and flues aren't blocked up and air vents aren't covered

Buying a detector for your home

The most important thing to find out when buying a carbon monoxide alarm is if it meets current British and European safety standards.

Look for an alarm that carries the EN 50291 standard and the British Standards Kitemark. Don't buy an alarm that doesn't meet these standards.

Always choose an audible alarm, so that you'll be alerted if you're asleep, and closely follow the manufacturer's instructions when installing it.

Getting extra help

There's lots of help out there to help you stay safe. The Be Alarmed! Campaign is run by Energy UK on behalf of Britain's six major gas and electricity companies and is supported by more than 40 other organisations.