(CNN) Carbon monoxide is a gas that has no odor, color or taste. You wouldn't be able to see or smell it, but it can be very dangerous to your health and even fatal.
Sources of carbon monoxide, according to the U.S. Environmental Protection Agency, include:
• Unvented kerosene and gas space heaters
• Leaking chimneys and furnaces
• Back-drafting from furnaces
• Gas water heaters, wood stoves and fireplaces
• Gas stoves
• Generators and other gasoline powered equipment
• Automobile exhaust from attached garages
• Tobacco smoke
Dangerous situations occur when carbon monoxide is trapped in poorly ventilated, contained spaces where people are, according to the Mayo Clinic. Carbon monoxide poisonings are sometimes seen when people attempt to use generators indoors after a power outage.
If there is too much carbon monoxide in the air you are breathing, your ability to absorb oxygen can be diminished, resulting in serious tissue damage.
More than 400 Americans die every year from unintentional carbon monoxide poisoning, according to the Centers for Disease Control and Prevention, and it is responsible for more than 20,000 people visiting the emergency room annually.
The initial symptoms are flu-like, but without a fever. They may include dull headache, weakness, dizziness and nausea. High-level poisoning can result in vomiting, shortness of breath, confusion, blurred vision and loss of consciousness.
In residential circumstances where carbon monoxide problems slowly develop, victims may mistake their symptoms for the flu. When carbon monoxide levels are higher and develop more rapidly -- for example, from generators in residential spaces -- mental confusion can set in rapidly. Victims may lose muscle control without being aware of the flu-like symptoms and will probably succumb to poisoning if they are not rescued.
Prolonged exposure to carbon monoxide levels of about 1 to 70 parts per million usually doesn't result in symptoms, although some heart patients may feel increased chest pain, according to the Consumer Product Safety Commission. Headache, fatigue and nausea may occur when carbon monoxide levels increase and stay above 70 parts per million. Greater danger occurs above 150 to 200 parts per million.
Go outside and get fresh air immediately if you believe you are experiencing any of these symptoms, and call the fire department. Contact a doctor immediately so that he or she can confirm carbon monoxide poisoning.
You can take several precautions to prevent carbon monoxide poisoning, according to the Consumer Product Safety Commission.
• Install a carbon monoxide alarm in the hallway near every area of your home that is used for sleeping. Make sure furniture or draperies do not cover the alarm. Travel carbon monoxide alarms are also available for use elsewhere.
However, in your home, an alarm is not a substitute for making sure that appliances that can produce carbon monoxide are in good repair and safe.
• Check to see that your appliances are installed and comply with building codes and manufacturer's instructions. Qualified professionals should install most appliances.
• Get your heating system professionally inspected and serviced every year, as well as chimneys and flues.
• Do not use charcoal inside your house or your garage, vehicle or tent.
• In an attached garage, even if the door is open, do not leave a car running.
• Do not operate unvented fuel-burning appliances in a room where people are sleeping
• Do not operate a portable generator or any other gasoline engine-powered tool in or near any house, garage or other enclosed space.
• If a carbon monoxide alarm sounds, go outside and call 911 immediately. Do not return to the building until emergency services personnel gives you the all-clear.
You can learn more about carbon monoxide from the EPA and the CDC.