Carbon monoxide is a poisonous gas that is both colourless and odourless. It The chronic poisoning, from regular exposure to low levels of carbon monoxide, may be a far more serious problem than has been realized. Because it cannot be detected by the senses, and because the initial symptoms of carbon monoxide poisoning are quite general (headaches, tiredness, dizziness), the number of victims of non-fatal poisoning that suffer from permanent central nervous system damage is estimated to be even larger. The magnitude of the health hazard due to carbon monoxide, both fatal and non-fatal, is huge and poisonings are probably more prevalent than is generally recognized. Carbon monoxide has been investigated in connection with cot death syndrome, for example, and may also trigger heart attacks in people suffering from coronary heart disease.
CO inhalation and poisoning is mostly a winter and domestic phenomenon: in Belgium around 70% of cases occur in the home (5% in shower cubicles inappropriately installed in small spaces); 24% during fires; 4% are suicide attempts; and 1% accidents at work. Around 2,000 people are hospitalized for CO poisoning each year.
The risk of carbon monoxide poisoning is increased during winter months when windows are closed and heaters are on. Leaks and blockages in chimneys, vents, flues, heating systems and gas appliances increase the risk; also cars and other gasoline engines left running in a closed garage. In the UK, most CO poisoning takes place within the home. According to a 1998 research, more reported cases occur in houses, including owner-occupied ones, than in flats; and two-thirds of victims are women, with the most common age group being 30 to 45.
According to a 1997 study in the UK, family doctors were almost incapable of recognizing non-fatal CO poisoning; out of 77 cases, only one was correctly diagnosed. The misdiagnoses included flu, viral infections, chronic fatigue syndrome and mental illness, including depression.
Carbon monoxide is the number one cause of accidental poisoning in the USA.
If you feel drowsy in front of the fire, it may be because there is a lack of oxygen, or carbon monoxide poisoning, or perhaps both.