It can be a silent killer.

  Unbeknowst to victims, they breathe in the odorless, colorless gas while going about normal, everyday tasks cooking dinner, watching television, reading a story to their children. It is poison to their bodies and if they dont escape it, it can cause illness, coma, even death.

  Each year, carbon monoxide poisoning causes almost 500 unintentional deaths in the United States, according to the Centers for Disease Control. More than 1,700 suicides are attributed to it. An estimated 3,000-5,000 people are treated annually for carbon monoxide poisoning in hospital emergency rooms, but it is believed that many more are misdiagnosed or never seek medical care.

  Most cases at Baptist Memorial Hospital occur during the winter months, said Joe Holley, M.D., F.A.C.E.P., emergency department director of Baptist Memorial Hospital-Collierville.

  Carbon monoxide is an odorless, colorless gas present in combustion fumes, such as those produced by automobiles, houseboat generators, small gasoline-powered engines, stoves, lanterns, burning charcoal and wood, and poorly functioning gas ranges or heating systems. Carbon monoxide from these sources can build up in enclosed or semi-enclosed spaces. Prolonged exposure can poison people and animals.

  When its cold people build fires, turn up gas heaters they burn whatever they can get their hands on, Holley said. Some people are even lighting up charcoal grills in their house. Theyre doing whatever they can to keep warm.

  The most common symptoms of carbon monoxide poisoning are headache, dizziness, weakness, nausea, vomiting, chest pain, and confusion. High levels of carbon monoxide can cause loss of consciousness and death. Unless suspected, carbon monoxide poisoning can be difficult to diagnose because the symptoms mimic other illnesses. 

  During winter months, emergency room personnel are more prone to suspect carbon monoxide poisoning when patients complain of these symptoms, Holley said.

  Carbon monoxide poisoning results when carbon monoxide molecules bind to hemoglobin, the substance that transports oxygen in the bloodstream. When carbon monoxide binds to hemoglobin, it prevents oxygen from binding to hemoglobin. To further complicate matters, carbon monoxide creates a bond that is 25 times stronger than the oxygen bond to hemoglobin, Holley said. Patients are treated with high-flow oxygen to allow carbon monoxide to unbind from hemoglobin and allow oxygen to bind. 

  All people are at risk for carbon monoxide poisoning. Certain groups unborn babies, infants, and people with chronic heart disease, anemia, or respiratory problems are more vulnerable to its effects.

  You can take simple precautions to prevent carbon monoxide poisoning. The CDC recommends that:

• All fuel-burning appliances: such as furnaces, water heaters, and gas dryers are properly installed, maintained, operated, and inspected periodically as recommended.
• Fireplace chimneys and flues are periodically checked and cleaned.
• Unvented fuel-burning space heaters are used only while someone is awake to monitor them, and doors or windows in the room are open to provide ventilation.
• Automobile exhaust systems, including catalytic converters, are routinely inspected for defects, and tailpipes are routinely inspected for blockage by snow, mud, or other substances.
• Carbon monoxide detectors are properly installed and maintained in homes, houseboats, workplaces, and other appropriate places; carbon monoxide detectors should be placed in hallways near sleeping areas.
• Swimming and other recreational activities take place in areas away from where gasoline-powered engines vent their exhaust.
• Portable electricity generators are not used in enclosed areas or in areas where the exhaust may vent into a home.
• Never use a gas range or oven to heat a home and never use a grill, lantern, or camping stove inside a home, tent or camper. Never run a gas-powered engine in an enclosed space.
• If you have an attached garage, make sure the insulation barrier within the walls adjacent to the house was properly installed to prevent carbon monoxide fumes from leaking into a living area. 
• Never warm up a car engine in an attached garage with the garage doors closed.

  And remember, seek immediate medical attention if you think you are suffering from carbon monoxide poisoning.