Information About Carbon Monoxide

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Carbon monoxide (CO) is a colorless, odorless, poisonous gas created when fossil fuels (such as wood, oil, natural gas and kerosene) do not burn completely. CO is the leading cause of accidental poisoning deaths in the U.S. Since you can't see it, taste it or smell it, CO can kill you before you know it's there. 

Exposure to lower levels of CO over time can be just as dangerous as exposure to higher levels for a few minutes.

Sources of CO in Your Home

In the home, dangerous levels of CO can occur if fuel-burning appliances are not working properly or are used with inadequate ventilation. Some common sources of CO around the home include:

  • Furnaces and water heaters that burn oil, propane, or natural gas
  • Fireplaces and wood stoves
  • Gas ranges and ovens
  • Gas dryers
  • Generators that run on gasoline, propane, or natural gas
  • Space heaters that burn fuels (especially kerosene)
  • Charcoal or gas grills
  • Automobiles, motorcycles, mopeds and other motor vehicles
  • Yard equipment with gasoline-powered engines (including lawn mowers, snow blowers, and chain saws)

Chimneys, flues, and vents (used with furnaces, water heaters, fireplaces, wood stoves, etc.) also can cause dangerous levels of CO to build up if they are misused, poorly maintained, or otherwise fail to provide adequate ventilation for toxic gases. 

Who is Most at Risk from CO?

Although anyone can suffer from CO poisoning, children and unborn babies, older people, and people with heart or lung diseases all are at greater risk from CO poisoning than other people. Also, if you have gas or oil heat, natural gas appliances, a fireplace, or an attached garage in your home your risk might be higher than individuals without such amenities.

Each year, hundreds of people die from CO poisoning in their homes. Thousands more become ill and require medical treatment. Some suffer lasting harm, including brain damage. According to the U.S. Consumer Product Safety Commission, there were 137 non-fire related CO deaths in 2000 associated with the use of various consumer products, excluding motor vehicles. The specific types of equipment involved were:

  • Heating systems (including propane, natural gas, and oil furnaces, gas- and wood-burning fireplaces and stoves, and kerosene space heaters) (82 deaths)
  • Engine-powered tools (not including automobiles) (27 deaths)
  • Gas ranges and ovens (11 deaths)
  • Charcoal grills (8 deaths)
  • Gas water heaters (3 deaths)
  • Camp stoves and lanterns (3 deaths)
  • Other/multiple appliances (3 deaths) - Numerous other CO deaths and injuries also are attributable to fires (smoke inhalation) and to the improper use of motor vehicles.

What are the Symptoms of CO Exposure?

The symptoms of CO exposure can vary greatly from one person to the next. The types of symptoms experienced, however, will generally depend on the concentration and length of the exposure as well as the general health of the person exposed. High concentrations of CO are dangerous for even brief periods. Exposure to lower levels of CO over several hours can be just as dangerous as exposure to higher levels for a few minutes.

CO is an insidious poison that works by displacing oxygen in the bloodstream of the victim. Its symptoms often are mistaken for the flu or other illnesses. At low levels, symptoms of CO poisoning may include:

  • Headache
  • Fatigue
  • Sleepiness
  • Weakness
  • Nausea
  • Vomiting
  • Dizziness
  • Confusion
  • Tightness in the chest
  • Trouble breathing
  • At high levels, loss of consciousness, coma, and death can occur within a short time.

If you or any member of your household experiences symptoms consistent with CO poisoning you should:

  • Get fresh air immediately - Everyone should get out of the building at once. Do not go back inside until any problems have been identified and corrected.
  • Call for help - Dial 9-1-1 or your local emergency number from a nearby telephone.
  • Seek medical attention right away - Get help even if you or others feel better after leaving your home. Blood or breath tests may be used to accurately diagnose CO poisoning.
  • Have your home checked - Contact a qualified professional to inspect your home and correct any problems that may have resulted in an exposure to CO.

Should I Install a CO Detector in My Home?

When properly installed and maintained, CO detectors can give you early warning of accumulating CO and provide an opportunity to escape before you experience symptoms or succumb to the poisonous gas. While many different models of CO detectors are available, we most highly recommend CO detectors that: 1) plug into a wall outlet, 2) have a battery backup, and 3) provide a digital display. Such detectors are easy to install, should function in the event of a power failure, and can provide useful information regarding concentrations of CO in the home.

As with smoke detectors, care should be taken in selecting and installing CO detectors in your home.

  • Be sure to only use CO detectors that carry the label of an independent testing laboratory.
  • Battery-powered CO detectors typically use 9-volt batteries as their source of power and can easily be installed by most homeowners. Certain models of CO detectors now also come with 5-year lithium batteries. These CO detectors are highly reliable and require less maintenance than other types of CO detectors.
  • "Plug-in" CO detectors run on household current, and are easy installed by most homeowners. Certain plug-in CO detectors may use batteries as a back-up source of electricity during power outages. If your plug-in CO detector does not have a battery back up, you may wish to install at least one battery-powered CO detector in the home for protection in the event that household current is interrupted. Also, be sure that the outlet used is not connected to a light switch that could allow someone to accidentally turn off the power.
  • If the required electrical wiring is provided in your home, hard-wired CO detectors can be used. Hard-wired CO detectors run on household current and should be installed by a qualified electrician. Certain hard-wired CO detectors may use batteries as a back-up source of electricity during power outages. If your hard-wired CO detector does not have a battery back up, you may wish to install another battery-powered CO detector in the home for protection in the event that household current is interrupted.
  • For optimal safety, CO detectors can be installed on every level of the home. If, however, you are only going to have one CO detector, be sure to install it in or near the primary sleeping area of your residence. Placement of CO detectors near bedrooms is essential to ensure that they will be able to alert sleeping residents to the threat of accumulating CO. Follow all manufacturer's instructions and recommendations to ensure the proper installation and placement of your CO detectors.
  • Combination Smoke/CO Detectors - Certain models of smoke detectors also function as CO detectors. Remember that unless you purchase one of these special detectors, your regular smoke detector will not alert you to the presence of CO in your home. Find out more about smoke detectors, please visit our Information About Smoke Detectors web page.

What Should I Do if My CO Alarm Goes Off?

If your CO alarm goes off always assume that it is a genuine emergency. Quickly take the following steps:

  • Operate the reset button to temporarily quiet the alarm. Do not wait to see if the alarm sounds again.
  • Immediately seek fresh air. Get everyone out of the building as soon as possible.
  • Call 9-1-1 or your local emergency number from a nearby telephone. Follow any instructions provided by the emergency operator.
  • Don't go back in until any problems have been corrected.

CO Safety Tips

With CO, prevention is always the best protection. By observing the following safety tips you can help keep you and your family safe from CO poisoning:

  • When purchasing new heating and cooking equipment, select factory-built products approved by an independent testing laboratory. Do not accept damaged equipment. Have fuel-burning appliances installed by qualified professionals. Insist that all applicable fire safety and building codes are followed.
  • Before enclosing central heating equipment in a small room, check with your fuel supplier to ensure that enough air is provided to support proper combustion.
  • Maintain appliances according to the manufacturer's instructions. Have appliances checked regularly to ensure that they are working safely. Do not attempt repairs unless you have all the required training and tools.
  • Have all fuel-burning household heating equipment (fireplaces, furnaces, wood stoves, and space heaters) inspected and cleaned each year before cold weather sets in. Make needed repairs before the equipment is used.
  • Have all chimneys and chimney connectors checked and cleaned annually to ensure proper ventilation.
  • When using a fireplace, be sure to open the flue completely to ensure adequate ventilation.
  • Vent a gas range to the outside of your home. Crack a window and run the exhaust fan whenever you cook.
  • Never use a gas range or oven to heat a room - even for just a short time.
  • Due to significant hazards from both fire and CO poisoning, kerosene heaters are illegal in many jurisdictions. Always check with local authorities before buying or using a kerosene heater in your home. If you do use a kerosene heater, always remember to open a window slightly whenever fuel is burning. Also, be sure to refuel the heater outside, after the device has cooled.
  • If you need to warm up a vehicle, remove it from the garage immediately after starting the ignition. Do not run a vehicle or other fueled engine or motor indoors, even if doors are open.
  • Have your vehicle inspected for exhaust leaks, especially if you are experiencing any symptoms of CO poisoning.
  • Lawnmowers, snow blowers, chainsaws, and generators that run on fuel all produce CO. Start all such equipment outside and never leave it running in or near the home.
  • Never use a charcoal or gas grill indoors, or in a garage, enclosed porch, tent or camper. Opening a door or window or running a fan may not be sufficient to keep CO from building up.

Finally, keep an eye out for any signs of a CO problem in your home. Such signs include:

  • The buildup of soot near fuel-burning appliances
  • A burning smell or other unusual odors
  • An appliance that keeps shutting off by itself
  • Yellow or orange flames from gas appliances (a bright blue flame usually indicates that the appliance is functioning properly)
  • Excess moisture inside of windows

For more information about CO, please call the City of Fairfax Fire Department, Office of Code Administration, at 703.385.7830 (TTY 703.293.7120).