Farm Safety - Carbon Monoxide: What is it and where does it come from?

Carbon monoxide is a colorless, odorless gas-a by-product of incomplete combustion. There is always some produced whenever we burn any carbon-based fuel such as natural gas, heating oil, wood, reconstituted wood logs, gasoline, charcoal, or any similar product.

Why should I be concerned about it?

Carbon monoxide can kill you. It is estimated that between 500 and 1,000 people die from carbon monoxide (CO) poisoning every year in the United States. In California, we usually hear of CO-related deaths from use of inappropriate indoor heaters or broken or improperly vented heaters.

Carbon monoxide interferes with the blood's ability to transport oxygen to body organs and can result in death at even very low levels. Because it is colorless and odorless, it is impossible to detect without instruments.

Symptoms of CO poisoning are similar to cold, flu, and allergy symptoms. Low levels of CO poisoning can result in headaches, lethargy, weakness, nausea, and muscle aches. Higher levels can cause paralysis, impaired judgment, coma, and death if left untreated.

Simply removing the victim from the source may not be enough to save his or her life. If you suspect CO poisoning, it is important to get immediate medical attention and treatment.

What are the common sources of carbon monoxide in the home?

The most common source of carbon monoxide in California homes is the use of inappropriate or improperly installed heating devices. Examples of inappropriate heating devices are charcoal grills, gas barbeques, camp stoves, or any device that does not explicitly mention that it may be used indoors. If in doubt, do not use the device inside until you call the manufacturer.

Poorly vented appliances can be gas cooktops, gas heaters, furnaces, wood stoves, or even water heaters. These are intended for indoor use and are usually installed correctly. However, inadequate maintenance, broken parts, or backdrafting because of the design and construction of the house can make these devices dangerous.

How can I tell if carbon monoxide is making me sick?

Do you feel better when you leave the house and go to work or school? Do you feel better when going outside? Do you start to feel a headache or tired when you return home at the end of the day? Are your symptoms shared by others in your home? Low levels of carbon monoxide can be very difficult to detect and the symptoms can appear to clear up when someone leaves the source. This does not mean that the problem is solved.

I have these symptoms, but my doctor is not sure if I might have this problem at home. What should I do?

Have your doctor call the Environmental Protection Agency at 1-800- 438-4318 to obtain a free copy of Indoor Air Quality: An Introduction for Health Professionals. Email:

What about a home test?

Home carbon monoxide detectors are a great idea. Many are available and range in price from about $10 to $300. Make sure that the device you purchase is certified by Underwriters' Laboratories (UL). Install it and maintain it according to the manufacturer's instructions. Many have a combination sensor/battery that must be changed about every two years. Carbon monoxide detectors usually use a chemical reaction sensor, which will deteriorate after a couple of years and must be hanged.

What if I think I or family members have been poisoned at home?

Call 911 and tell the operator why you think you need help. The fire department can come and check your home and ventilate it in an emergency. Ambulance crews can begin the necessary treatment. If you come home during heating season and find people unconscious in your house, call 911 from a phone away from the house. You may also be overcome by carbon monoxide if you attempt rescue on your own.

What is backdrafting?

Backdrafting occurs when a naturally vented appliance loses the chimney effect, which normally carries combustion by-products up the chimney. Backdrafting can occur with furnaces, fireplaces, woodstoves, and water heaters. This can happen during low wind conditions and when there is lower air pressure in the house than outside. Running a furnace, clothes dryer, bathroom fans, and a kitchen fan can cause backdrafting, as they move air out of the house, which must be replaced from the outside. If the doors and windows are all closed and very tight, the replacement air must come down a chimney and can cause a backdraft through any of these appliances.

How do we prevent backdrafting?

Try to start fireplaces and woodstoves when no other devices are removing air from the house. Once a draft is established, it is less likely to change into a backdraft, particularly in a properly vented and maintained device. If possible, have the water heater and furnace draw their intake air from the outside or away from the living area. If you see smoke coming back down a chimney, you have a problem that needs immediate attention.

How do I select someone to do my home maintenance?

Require licensed contractors for inspection and repair of your furnace and water heater. Check with the state regarding the status of their license and check with the local Better Business Bureau regarding any recent complaints. Ask for references and check them out. Make sure to select reputable and professional chimney sweeps to inspect and clean your chimney annually. If you burn a lot of wood, you may need a more frequent inspection. If we have an earthquake, inspect all chimneys and combustion appliances for any damage before using them.

How do I control carbon monoxide?

Carbon monoxide cannot be "controlled". We must keep it out of our living areas and avoid contamination of our indoor air. Make sure that all combustion appliances in the home are UL listed for indoor use. Do not burn charcoal or gas barbeque grills indoors. Keep garages vented and do not allow automotive exhaust to enter your home.

Why would a normally functioning furnace or water heater suddenly start to produce carbon monoxide?

A furnace or water heater would not suddenly start to produce carbon monoxide, but it may start to let it into your home. Possible reasons for this are that the heat exchanger has rusted or corroded, or the house has settled a bit and shifted. It is also possible that the chimney has developed an obstruction from a bird's nest, debris, or some other occurrence over the summer.

Is there any way to know that you have carbon monoxide coming in?

The best way is to get several good detectors and install and use them according to instructions. If you notice a heating appliance that makes a funny noise, starts making more noise than usual, if the furnace runs all the time, or if you smell some of the other combustion by-products, it's a good idea to get it checked by a professional.

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