Carbon monoxide poisoning happens from breathing in large amounts of carbon monoxide (CO).[1]
Carbon monoxide poisoning can be accidental, like if the oven's gas is left on by accident or a gas leak or caused by fires. It has often been used as a method of suicide.
Less than 200 people die per year from carbon monoxide poisoning in the UK, and that number seems to be decreasing. Around 400 people die in the US each year (published 2024).