Carbon monoxide is an odorless, colorless, non-irritating yet toxic and potentially lethal gas. Common sources of carbon monoxide are unventilated kerosene or propane heaters, gasoline engines, automobile exhaust, or fumes from carbon-based fuel heating systems. This is readily absorbed into the blood combining with hemoglobin to form carboxyhemoglobin thereby reducing oxygen delivery to the body specially the brain and the heart.
Depending upon the concentration and duration of exposure of carbon monoxide the symptoms may be acute or chronic including sleepiness, cherry red skin and mucous membranes, weakness, vomiting, cough, difficulty in breathing, seizures, depression, deafness, uncoordinated movements, coma.