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, 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
The main causes of carbon monoxide poisoning are outlined below.
Poorly installed or maintained appliances
Household appliances, such as cooking and heating devices, that are incorrectly installed and badly maintained are the main cause of accidental exposure to carbon monoxide. Correctly fitted and well mantained appliances should produce very little CO gas.
Damaged appliances can also produce higher levels of CO gas than normal and become dangerous.
Blocked flues and chimneys
Blocked flues and chimneys are another potential cause of carbon monoxide poisoning because they can stop CO gas escaping, allowing it to build up to dangerous levels in a room.
Enclosed or unventilated spaces
Burning fuel in an enclosed or unventilated space increases the risk of CO poisoning. For example, a car engine left running inside a garage or a faulty heating boiler in a poorly ventilated kitchen can emit potentially lethal levels of CO gas.
A car left running in a closed garage will take around 10 minutes to build up a lethal level of CO gas.
Paint fumes
Fumes from cleaning fluids and paint removers that contain methylene chloride (dichloromethane) can also cause carbon monoxide poisoning. When breathed in, methylene chloride is converted into CO gas.
