Carbon Monoxide
- What is carbon monoxide (CO)?
- What are possible sources of carbon monoxide in the home?
- What are the signs and symptoms of carbon monoxide poisoning?
- What are the health effects?
- Are there ways to lessen the risk of carbon monoxide poisoning?
- What should I do if I suspect a carbon monoxide problem?
- Can carbon monoxide be detected?
- Where should a carbon monoxide detector be installed?
- What should I do if the carbon monoxide detector alarm goes off?
- What should I do in case of emergency?
What is carbon monoxide?
Carbon monoxide (CO) is a colorless, odorless, poison gas. It is produced when liquid, solid, or gas fuel is burned.
Carbon monoxide (CO) is sometimes confused with carbon dioxide (CO2). Carbon monoxide is a poison, even at fairly low levels, while carbon dioxide is a normal part of the breathing process.
What are possible sources of carbon monoxide in the home?
Under certain conditions, any fuel burning vehicle, tool, appliance or other device or equipment can produce harmful levels of carbon monoxide. Common examples include:
- fuel-fired furnaces or boilers (nonelectric)
- space heaters with pilot lights or open flames (for example kerosene heaters, wood stoves or fireplaces)
- gas stoves or ovens, especially those with pilot lights
- dryers, water heaters and refrigerators that use gas or liquid fuel
- charcoal and gas grills
- lawnmowers, snowblowers, and other gasoline powered yard equipment run in an attached garage or basement
- cars, snowmobiles, trucks and other vehicles run in an attached garage
- tobacco smoke
What are the signs and symptoms of CO poisoning?
The early symptoms of carbon monoxide poisoning can be confused with flu-like symptoms—headache, dizziness and nausea. Breathing carbon monoxide causes these symptoms even in healthy people. It can also cause sleepiness, vision problems (including blurred vision), ringing in the ears, aching arms and legs, irregular breathing, fatigue and confusion. At very high levels, it causes loss of consciousness and death.
Breathing low levels of carbon monoxide over a few hours can have just as harmful effect as breathing high levels for a few minutes. If symptoms go away when you leave your home, but come back when you return, there may be a carbon monoxide problem in your home.
What are the health effects?
Nationwide, hundreds of people die from carbon monoxide poisoning every year, and thousands are treated in hospitals.
Carbon monoxide lowers the body’s ability to carry oxygen to vital organs such as the heart and brain. In general, the more carbon monoxide a person inhales, the more serious the damage that occurs. The elderly, young children, infants, fetuses, and people with anemia or heart or lung problems are more sensitive to the effects of carbon monoxide. During strenuous exercise, people are also more sensitive to the effects of carbon monoxide.
Are there ways to lessen the risk of CO poisoning?
The following is a list of tips to help reduce the risk of carbon monoxide problems:
- DO obtain and install a carbon monoxide detector.
- DO have your heating system, including your furnace, boiler, wood stove, chimney and venting system checked and serviced at least once each year. Have your chimney cleaned as often as is necessary.
- DO follow the directions that come with heating or cooking equipment.
- DO have your kitchen gas stove checked and serviced at least once a year.
- DO make sure that all heating, cooking, and other fuel burning devices are installed according to the company’s instructions. Follow all federal, state and local housing and building codes.
- DO make sure that stove pipes and other types of vents are tightly joined, and not cracked or rusty.
- DO use the proper fuel in space heaters and be sure they are properly vented to the outdoors.
- DO have an outside-venting exhaust hood installed above a kitchen gas stove. Use it when cooking.
- DO NOT allow engines to idle (run) in a garage that is attached to or beneath the house.
- DO NOT service autos or home heating and cooking appliances unless you have the correct tools, skills, and knowledge AND unless it is allowed by law and suggested by the maker of the product.
- DO NOT use a charcoal grill or hibachi in your home or garage.
- DO NOT use the kitchen gas stove for heating the apartment or the house.
- DO NOT allow snow or ice to pile up outside a gas appliance vent.
- DO NOT smoke cigarettes, cigars, pipes or other tobacco products inside the house or apartment.
While many causes of carbon monoxide problems can be prevented, this is not true in all cases. Sometimes problems occur, such as a blocked chimney or faulty furnace or gas stove, which cannot be predicted.
The presence and amount of carbon monoxide can also be affected by how airtight your house or apartment is. If a building is too airtight, it cuts down on the amount of fresh air entering and can allow levels of carbon monoxide to build up.
What should I do if I suspect a carbon monoxide problem?
If you think that you may have a carbon monoxide problem and no one is experiencing any of the symptoms of carbon monoxide poisoning, there are several things you can do.
If you are a tenant, and you think there may be a problem with your furnace, boiler, gas stove, or some other possible source of carbon monoxide, talk to your landlord. If you believe that a carbon monoxide problem is present and continues to be a problem, you may want to contact your local health officer or the district office of the Vermont Department of Labor and Industry.
Other possible resources for homeowners or tenants include: local fire department, fuel dealer or service technician, building inspector, local community action or weatherization program, district office of the Vermont Department of Health, heating and ventilating contractors or environmental services. Many of these companies and organizations are listed in the Yellow Pages of your local telephone book.
Can carbon monoxide be detected?
Yes. Since most dwellings have at least one possible source of carbon monoxide, the Vermont Department of Health recommends that homeowners and tenants install carbon monoxide detectors. These devices measure the amount of carbon monoxide in the air and sound an alarm at certain levels. Before purchasing a carbon monoxide detector for your home or apartment, be sure that it meets the requirements of Underwriters Laboratory (UL) standard 2034.There are many types of carbon monoxide detectors. Some operate only on batteries; some are “plug-ins”; and some have both features. Some detectors show the actual level of carbon monoxide in your home.
Information about carbon monoxide detectors is available from the Consumer Product Safety Commission, the federal Environmental Protection Agency and the Vermont Lung Association. See Indoor Air Links section of our Indoor Air Quality Resource Guide.
Where should a carbon monoxide detector be installed?
There are many opinions on where to put a carbon monoxide detector in a home. Ideally, a carbon monoxide detector should be placed on each level in your home. If you only have one carbon monoxide detector, place it in an area or hallway of the house or apartment that is near the sleeping area.
What should I do if the CO detector alarm goes off?
If your carbon monoxide detector alarm goes off, AND you or others in the household have some symptoms of carbon monoxide poisoning (like headaches and nausea), get out of the house and call for emergency medical help from a neighbor’s phone right away. Tell the doctor or emergency staff that you suspect carbon monoxide poisoning, and follow their advice.
If no one is feeling ill, it is possible that your carbon monoxide detector is not working correctly. One way to find out if a battery-operated detector is working is to take it outside. If the alarm continues, there may be something wrong with it. If there seems to be no problem with the detector or you cannot tell if there is a problem, you may want to contact your landlord, local fire department, heating contractor or gas company to assist you. They may be able to test for carbon monoxide gas and tell you whether there is a problem in your home. You also may want to contact the manufacturer of the detector.
Once you have had your home or apartment checked, it is important to take action to correct any detected problems. If you are a tenant and you need help talking to your landlord about the problem, contact your town health officer.
What should I do in case of emergency?
If anyone in the household has symptoms and you think it may be carbon monoxide poisoning, everyone should get out of the building right away. People should go outside for fresh air. If anyone is unconscious or not breathing, bring the person outside of the building into the fresh air also. If you know CPR, begin it as soon as possible.
From a safe location, call or have someone else call your local emergency service. Tell the doctor or emergency medical staff that you suspect carbon monoxide poisoning and follow their advice. Be prepared to tell them the address and directions on how to get there.
Also, have someone call the local fire department or service technician (like a furnace repairman, etc.) from a safe telephone location, and follow their instructions.
Make sure that no one goes back into the house until you are assured that it is safe.


