CO is a highly poisonous gas that weighs about the same as air.
At high concentrations, CO can kill without warning, sometimes in only minutes.
It cannot be seen, smelt, tasted, or felt, that's why it's known as the silent killer!
When you breathe in CO, it replaces the oxygen in your bloodstream, preventing essential supplies to your body tissues, heart, brain and other vital organs.
Where victims survive severe CO poisoning, they can be left with long-term brain damage such as poorer concentration, or causing mood swings, etc.
But even breathing-in lower levels of CO over a longer period, you can still suffer serious effects such as memory problems and difficulty concentrating.
Some people will be affected much more quickly:-
For other reasons, some people may be at higher risk: