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Carbon Monoxide: Colorless, Odorless, Dangerous

During the winter, when windows and doors are closed tightly and home heating systems are cranking, there is an increased risk of exposure to the gas carbon monoxide, also known as CO.

Gas boiler flame photo via Flickr | Creative Commons license

Gas boiler flame photo via Flickr | Creative Commons license

CO is a risk whenever there is combustion. Gas boilers and furnaces, water heaters, ovens, car engines, generators, and barbecue grills can all produce it. CO is colorless, odorless, and especially dangerous because it is so difficult to detect. If it builds up in a home while the occupants are sleeping, it can be fatal before anyone suspects a problem.

Where does carbon monoxide come from?

CO is a byproduct of combustion when there is not enough oxygen in the environment.

A gas-fired boiler or water heater, when it is functioning properly and supplied with abundant oxygen, gives off water vapor and carbon dioxide, or CO2. Carbon dioxide is a molecule that consists of one carbon atom plus two oxygen atoms. (The accumulation of carbon dioxide in the earth’s atmosphere contributes to global warming, but the gas is not poisonous to humans.)

However, if the appliance malfunctions, or if its ventilation is blocked, a lack of sufficient oxygen means that the burning process will produce CO, or one carbon atom plus one oxygen. This combination is poisonous. That’s why gas-fired appliances must be ventilated: more to supply them with abundant oxygen than to let the byproducts escape.

Symptoms of CO poisoning

Headache, fatigue, shortness of breath, nausea, dizziness, and flu-like symptoms can all result from CO exposure. Other warning signs are condensation on your walls or windows, pets that act sluggish, and dying plants.

CO combines with hemoglobin in the blood, preventing it from delivering oxygen to the body’s tissues. If you believe you may be experiencing carbon monoxide poisoning, seek fresh air immediately and get medical attention.

You can reduce your risk of CO exposure by taking common-sense precautions:

  • Install CO detectors (or smoke-and-CO detectors) and make sure they have working batteries. Even hardwired CO detectors have back-up batteries that should be changed periodically.
  • When you’re indoors, never use a grill, camp stove, generator, or anything else that burns fossil fuels. That includes enclosed areas such as garages.
  • Don’t use your oven to heat your home. If you need help paying your heating bills, see our previous post, Where to Find Help with Heat.
  • Have your heating contractor give your system a checkup each year to make sure it’s functioning the way it should. If you see that it is not working properly, call a contractor right away.
  • If you use a space heater, place it on a hard, level surface to reduce the risk of tipping. Keep the area around the heater clear. Flammable items like paper, clothing, curtains, or bedding must be at least three feet away. Be sure to turn off the space heater when you leave the room and before you go to bed.
  • In your oven, do not use aluminum foil to cover the oven bottom or racks. This blocks the air flow and can lead to CO generation.
  • Do not leave your car running in an attached garage under any circumstances, even with the door open. In a detached garage, make sure to leave the door open when the car is running.

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