Carbon monoxide is produced when fuels such as gas, oil, coal and wood do not burn fully.

Burning charcoal, running cars and the smoke from cigarettes also produce carbon monoxide gas.

Gas, oil, coal and wood are sources of fuel used in many household appliances, including: boilers, gas fires, central heating systems, water heaters, cookers & open fires

Incorrectly installed, poorly maintained or poorly ventilated household appliances, such as cookers, heaters and central heating boilers, are the most common causes of accidental exposure to carbon monoxide.

The risk of exposure to carbon monoxide from portable devices may also be higher in caravans, boats and mobile homes.