Questions and Answers About Carbon Monoxide(CO) and CO Detectors

Portrait of a Killer

What is carbon monoxide? 

Carbon monoxide, known by the chemical formula "CO" is a poisonous gas that kills more than 250 people in the United States alone every year. You can't hear, taste, see or smell it. It's nicknamed the "silent killer" because it sneaks up on it's victims and can take lives without warning.

What are the sources of CO? 

CO is a by-product of incomplete combustion. CO sources can include malfunctioning appliances -- including furnace, stoves, ovens and water heaters --that operate by burning fossil fuels such as natural or liquefied petroleum (LP) gas, oil, wood or coal. When malfunctioning appliances aren't adequately ventilated, the amount of CO in the air may rise to a level that can cause illness or even death.

Other CO sources include vehicle exhaust, blocked chimney flues, fuel-burning cooking used for heating purposes, and charcoal grills used in the home, tent, camper, garage or other unventilated area.

How does CO affect the human body? 

When victims inhale CO, the toxic gas enters the bloodstream and replaces the oxygen molecules found on the critical blood component hemoglobin, depriving the heart and brain of the oxygen necessary to function correctly. Sensing the body's need for more oxygen, the victims heart rate increases to pump more blood to the body's organs. If a person continues to inhale CO, he or she faces the risk of breathing difficulty, cardiac trauma, brain damage, coma or even death.

What are the symptoms of CO poisoning?

CO poisoning victims may initially suffer flu-like symptoms including nausea, fatigue, headaches, dizziness, confusion and breathing difficulty. Because CO poisoning often causes a victims blood pressure to rise, the victim's may take on a pink or red cast.

Avoiding CO

How can I tell if there is a risk of CO poisoning in my home? 

Have your fuel-burning appliances inspected by a qualified technician at least once a year.

Be alert to these danger signs that signal a potential CO problem:

• streaks of carbon or soot around the service door of your fuel-burning appliances;
• the absence of a draft in your chimney (indicating blockage);
• excessive rusting on flue pipes or appliance jackets;
• moisture collecting on the windows and walls of furnace rooms;
• fallen soot from the fire place;
• small amounts of water leaking from the base of the chimney, vent or flue pipe;
• damaged or discolored bricks at the top of your chimney; and
• rust on the potion of the vent visible from the outside of your home.

Also, recognize that CO poisoning may be the cause when family members suffer from flu-like symptoms that don't disappear but improve when they leave home for extended periods of time.

How can I prevent CO poisoning? 

The most important steps are preventive ones. Have a qualified service professional inspect your fuel-burning appliances at least once a year. Install UL listed CO detectors outside of sleeping areas and near all fuel-burning appliances.

Other precautions include:

• avoid using charcoal grills inside the home, tent or camper, or in an unventilated garage.
• don't allow vehicle exhaust fumes to enter the home; and
• make sure all fuel-burning appliances are properly ventilated.

CO Detectors -- Tools to Alert Your Family

What should I look for when I buy a CO detector? 

Rather than looking for specific features, look for the UL Mark with the adjacent phrase "Single Station Carbon Monoxide Detector."

UL listed CO detectors are designed to detect elevated levels of CO and sound an alarm to alert your family of a potential poisoning risk. Although CO indicator cards and other devices on the market are also intended to detect elevated levels of CO, most aren't designed with an audible alarm. The presence of an audible alarm may be significant -- especially while you and your loved ones sleep.

How can I protect my family when we're traveling? Working in the garage? 

UL evaluates and lists CO detectors intended for use in recreational vehicles (RVs) and areas such as garages attics where dampness, humidity and temperatures aren't controlled as in the living space of the home. CO detectors used in these areas comply with additional requirements designed to address the special conditions often present in these environments.

UL also evaluates CO travel alarms. These devices are equipped with a mounting bracket for temporary mounting only.

UL Listed CO detectors intended for use in these environments are marked accordingly near the UL Listing Mark.

Do CO detectors operate differently than smoke detectors? 

Although they may look and sound similar, CO and smoke detectors are designed and intended to detect two separate, distinct hazards. Therefore, to help protect your family from both hazards, it's important to install both UL Listed CO detectors and smoke detectors.

How do I install my CO detector? 

Follow the installation instructions found in the manufacturer's use and care booklet that accompanies the product. Proper installation is an important factor in receiving optimum performance. It's important to follow these instructions exactly.

How do I take care of my CO detector? 

Like smoke detectors, CO detectors need to be tested regularly and cleaned as indicated in the manufacturer's use and care booklet. If the unit is wired directly into your home's electrical system, you should test it monthly. If your unit operates off a battery, test the detector weekly and replace the battery at least once a year.

Should I follow any safety tips for using and maintaining my CO detectors? 

As with any product, read the manufacturer's use and care booklet for installation and maintenance guidelines. Keep these instructions on file for future reference. If your unit operates off a battery, never allow anyone to "borrow" the battery. Like any appliance or power tool, a CO detector can't work unless it has a functioning power source.

Will exposure to other household gases or vapors cause the CO detector to false alarm? 

When UL evaluates samples of residential CO detectors, consideration is made that your home may contain moderate levels of cleaning chemicals and other substances. UL 2034, the Standard UL engineers and technicians use to test residential carbon monoxide detectors, includes exposure tests to normal concentrations of methane, butane, heptane, ethyl acetate (nail polish remover), isopropyl alcohol (rubbing alcohol), carbon dioxide and propane -- all gases that would typically be found in a home.

You should, however, keep these chemicals away from your CO detectors. Low exposure over an extended period of time could damage the sensing device and cause your detector to sound a false alarm.

What do I do if my CO detector alarm goes off? 

Immediately ventilate your home by opening windows and outside doors. If anyone in your household is experiencing flu-like symptoms, including nausea, fatigue, headaches, dizziness, confusion and breathing difficulty, immediately call the fire department and evacuate everyone in your home. Be sure to check infants and others who have trouble explaining their symptoms. Do not let anyone re-enter the premises until the problem is corrected.

If no one in the household has flu-like symptoms, again, ventilate your home, turn off all fuel-burning appliances and immediately call a qualified technician to inspect for sources of CO. Do not restart these appliances and continue to ventilate your home until the problem is corrected.

Because you've provided ventilation by leaving your windows and doors open, the CO buildup may be dissipated by the time help responds. Although your problem may appear to be temporarily solved, it's crucial that the source of CO is determined and appropriate repairs are made.

Remember, an alarm indicates elevated levels of CO in your home. CO is called the "silent killer" because it cannot be seen or smelled. Some people may be exposed to dangerous levels of CO and not feel any symptoms. Regardless of whether you feel symptoms, never ignore the alarm.

For more information about UL, the UL Mark or consumer product safety, contact:

Underwriters Laboratories Corporate Headquarters

333 Pfingsten Road Northbrook, IL 60062 (708) 272-8800