Carbon Monoxide: The Silent Killer

When gas (or any fuel, including wood, coal or oil) doesn't burn properly, it produces carbon monoxide (CO) as a by-product. A correctly installed, well-maintained appliance with a clear flue and enough fresh air burns cleanly and produces negligible CO. A faulty one doesn't, and because CO is colourless, odourless and tasteless, there's no natural warning that anything is wrong.

You're at risk if:

• Your appliance was poorly installed
• Your appliance isn't working properly
• Your appliance hasn't been checked for safety or maintained regularly
• There isn't enough fresh air in the room
• Your chimney or flue is blocked
• You allow anyone other than a Gas Safe registered engineer to install or maintain your appliances

Warning signs to watch for

On the appliance itself: yellow or orange flames instead of a crisp blue, soot or stains around the appliance or on the wall above it, and a pilot light that keeps going out. In people: headaches, dizziness, nausea, breathlessness, tiredness and confusion that ease when you leave the house and return when you're back. These are easy to mistake for flu or tiredness, which is part of what makes CO so dangerous.

If you suspect a carbon monoxide leak

• Turn off the appliance if it's safe to do so, and open doors and windows
• Get everyone out of the property into fresh air
• Don't operate any electrical switches, including light switches
• Call the National Gas Emergency Service on 0800 111 999
• Seek medical help immediately if anyone feels unwell

How we help you avoid it

The best protection is prevention: appliances installed and serviced by a Gas Safe registered engineer, flues kept clear, and an audible CO alarm fitted in any room with a gas appliance. If you're a landlord, this ties directly into your annual gas safety certificate obligations. See our gas safety help and advice page for further reading, including the HSE's guidance.