Carbon Monoxide

Carbon Monoxide, or CO, is a byproduct resulting from the incomplete combustion of fuels such as natural gas, propane, heating oil, gasoline, kerosene, coal and wood, just to name a few. In the home, appliances utilizing these fuels such as furnaces and boilers, portable heaters, cooking appliances, clothes dryers, fireplaces and heating stoves can produce significant levels of CO. Even exterior appliances such as charcoal and gas grills, stand-by electric generators and automobiles can be a potential source of Carbon Monoxide inside your home.

Commonly called the "silent" or "invisible" killer, Carbon Monoxide is an odorless, colorless and tasteless gas. Short-term exposure to high-enough levels of CO (CO poisoning) can cause symptoms such as dizziness and confusion, nausea and vomiting, weakness and chest pain, just to name a few. Long-term health effects can include tissue and neurological damage, and in high enough concentrations and exposures, death. Each year in the United States, CO poisoning claims hundreds of lives, and several thousand more victims require medical attention. Numerous other untold victims are poisoned but do not realize it because of the undetectable nature of CO, and how the symptoms of CO poisoning mimic other ailments such as the flu.

Some groups such as neonates, infants, and people with chronic heart disease, anemia and respiratory problems are more susceptible to the effects of CO poisoning. However, anyone exposed to high-enough levels of CO are at risk for poisoning. In many documented cases, people have died from CO poisoning in their sleep, some of which never experienced any symptoms at all.

Carbon Monoxide is easily absorbed into the bloodstream via the lungs where it readily attaches to the hemoglobin in the red blood cells. The hemoglobin is the part of the red blood cell that transports oxygen from our lungs to our cells, and returns carbon dioxide for expulsion. Amazingly, hemoglobin will accept Carbon Monoxide up to 200 times more readily than oxygen, thus inhibiting the blood's ability to carry oxygen to the body's tissue and cells. In addition, because of Carbon Monoxide's ability to bind to hemoglobin, CO is slow to be expelled from the body, making it a very serious health threat.

On this page, we will discuss how to prevent Carbon Monoxide problems, Carbon Monoxide alarms, and what to do if a Carbon Monoxide incident arises.


	Fuel-burning appliances such as furnaces and hot water heaters might produce Carbon Monoxide if not serviced appropriately.

Many homes now feature very efficient insulation, doors and windows which keeps air from getting in, and out. This obviously means that should you get Carbon Monoxide in your home, it will have a difficult time exiting naturally. This same air-tight condition can also help produce Carbon Monoxide, as a flame that has less than adequate oxygen for combustion will produce CO. A good first step in helping to prevent a CO problem in your home is to have a qualified technician annually inspect and maintain all fuel burning appliances, and their ventilation systems, irregardless of if they are gas or oil-fired.

When neglected, gas and oil-fired appliances such as furnaces, boilers, hot water heaters, clothes dryers, cook tops, ovens, gas fireplaces and their associated ventilation systems are prime sources for Carbon Monoxide. In addition, their inefficiency resulting from needed maintenance costs you money and in the case of fuel oil furnaces, can lead to "backfires" that will leave your house filled with a greasy, black smoke which stains walls, ceilings and other parts of your interior. Be sure to have these systems serviced annually by a qualified technician.


Proper installation and maintenance of all ventilation systems is critical. This includes all rigid and flexible duct work, chimneys and exterior vents.

It is also very important to make sure that all exhaust is being properly vented to prevent CO from finding it's way into your home. Both rigid and flexible ductwork which is used to vent these appliances is prone to dislodgement and damage. Repairing ductwork may seem like an easy enough task for a do-it-your-self'er, but be warned, making a mistake here could be deadly. Be sure to ask the technician servicing your appliances to also inspect their ventilation systems.

Remember, duct work from wood, coal and pellet stoves should also be installed and maintained by a professional. Fireplace doors and fireplace inserts will also allow CO into the home if they are not installed correctly.

Homeowners would also be advised to leave the repair and replacement of furnaces, boilers, hot water heaters, etc., to a qualified professional. Exterior vents for interior gas and oil appliances must be installed properly. Intake and exhaust vents which are placed in proximity to each other can re-circulate emissions, introducing Carbon Monoxide to the home instead of safely disposing of it.

While we are on the subject, have your chimney inspected and cleaned each year. Cracks or damage to the chimney flue can serve as an avenue for CO to invade your home by. Bird's nests, creosote buildup, and other debris can keep the chimney from functioning properly, allowing CO to back-up into your home. In addition, excessive creosote deposits lead to chimney fires, so get them cleaned.


	Kerosene heaters have the potential to cause fires and produce carbon monoxide. Always follow the manufacturer's instructions for their use and maintenance.

Another CO producing appliance that is used for heating is natural gas, propane and kerosene space heaters. Some of these heaters are permanently installed and require venting to the exterior like other heating appliances. All of the maintenance concerns associated with the before mentioned heating appliances also applies to space heaters.

Portable space heaters normally are not designed to vent to the exterior of your home, although consideration must still be given to ventilation, such as opening a window partially. Maintenance must be performed on these appliances also, as even an improperly trimmed wick can significantly increase the level of CO produced by these types of heaters.

Although manufacturers certainly design portable gas heaters to be as safe as possible, they are still a potential source for CO and a fire hazard. This has led some jurisdictions to ban their use. Check to make sure that the use of these types of heaters are allowed in your area, and by all means read, understand and strictly follow the manufacturer's instructions for their use and maintenance.

During a winter power outage, it is tempting to use outdoor charcoal and gas grills, and camping stoves, heaters and lanterns for heating and lighting the home. This is an incredibly dangerous practice as these appliances can produce a large amount of Carbon Monoxide, and are also considerable fire hazards when used indoors. Using your gas oven, range or cook top for heating the home can also produce a significant amount of CO.

Never run a portable electric generator inside the home, inside THE GARAGE, OR CLOSE ENOUGH TO THE HOME OR IN A MANNER THAT MAY ALLOW EXHAUST AND carbon monoxide TO ENTER.


Never operate a portable electric generator inside your home. Position them as far as possible from the structure to help reduce the possibility of introducing Carbon Monoxide to the interior.

These units are not designed to run inside the home as they produce considerable Carbon Monoxide. There have been many documented cases of deaths from CO poisoning resulting from the running of portable electric generators inside the home during power outages, so do not do it. Strictly follow the manufacturer's instructions when using portable electric generators.

Renters should be just as concerned about Carbon Monoxide as homeowners. Speak with your landlord about their preventative measures concerning CO. Landlords have a legal obligation to annually service gas and oil appliances, and provide renters with a safety certificate upon request. Also talk to your landlord about installing a CO detector if none are present, as this is commonly also required by law.

Carbon Monoxide doesn't always necessarily originate from inside your home. Common sources of CO from the exterior of your home are automobiles, gasoline-powered lawn tools, electric generators, and charcoal and gas grills. CO from these and other sources can find its way from the exterior to the interior of your home, and there are several scenarios that you should be aware of.


	Garages can trap the exhaust of automobiles, lawn tractors, snow blowers, generators and other fuel burning implements, and facilitate the introduction of the CO they produce to the interior of your home. An open garage door does not offer adequate ventilation. Remove these implements completely from your garage when they are running.

With many homes now having attached garages, it is not uncommon for CO to originate in the garage, and migrate to inside the home. During inclement weather, it is a common practice for people to warm-up automobiles, tractors, and snow blowers, run portable electric generators or use grills, inside the garage. What happens is when the door from the garage to the interior is opened, a large influx of Carbon Monoxide can be introduced to the interior of the home driven by wind or pulled along when colder air rushes into the warmer interior of the home.

Remove automobiles, tractors, snowmobiles, etc. from the garage immediately after start-up and idle them outside of the garage, and close the doors afterwards to prevent CO from entering the garage while they idle. Start lawn mowers, gasoline-powered tools, etc., outside and away from the garage and leave them there. Do not use grills or portable electric generators inside the garage. Using any of these items inside the garage, whether it is attached to the home or not, is an unsafe practice regardless of it you have the garage doors and windows open for ventilation. The normal circulation of air will not provide enough ventilation.

Using items such as grills, lawn tools, pressure washers and electric generators in proximity to open windows, doors and vents can certainly also introduce CO to inside your home from the exterior.

Even with excellent preventative measures, a Carbon Monoxide incident can still occur in your home at any time. Unless you have a properly functioning CO alarm (previously known as CO detectors) installed in your home, it is virtually impossible to determine the presence of Carbon Monoxide. Remember, CO is an odorless, colorless, tasteless gas, so a Carbon Monoxide alarm is a wise, inexpensive and essential investment in your family's safety.


Carbon Monoxide alarms designed for wall and ceiling mounting. The unit on the right is a combination CO & smoke alarm.

Carbon Monoxide alarms are similar in appearance to smoke alarms and protect you in a similar manner. When functioning properly, they constantly monitor the atmosphere inside your home for the presence of CO, emitting a warning when a specified level of Carbon Monoxide is detected. It is important to note that while some CO alarms may have a similar appearance to smoke alarms, unless the unit is specifically designed to detect smoke in addition to CO, do not utilize it as a smoke alarm.

In fact, there are several brands and designs of CO alarms available. As mentioned, some alarms are dual-purpose, working to detect Carbon Monoxide and smoke. Some units feature a digital read-out of the level of CO in the atmosphere.

The consumer also has several options regarding how the unit is powered. Battery operated units are popular but require the owner to annually change the batteries to keep them in continual operation. Some units are powered by replaceable modules which are good for several years. The drawback to these alarms is availability of the modules. Other units are designed to be plugged into a wall outlet or hard-wired directly to a 120 volt connection. If you purchase a wall-plug or hard-wire model, make sure that it has a battery back-up so the alarm continues to function during power outages. Never connect a plug-in unit to an outlet, or install a hard-wired detector to a circuit that is operated by a wall switch. It is imperative that you promptly change the batteries when recommended and/or needed for those models that use them, regardless if the battery is the primary or back-up power source.

Make sure the unit you purchase has been approved by an independent testing company, such as Underwriters Laboratory (UL). Regardless of which model you purchase, for the unit to effectively protect you and your family, you need to:

FULLY READ AND UNDERSTAND THE MANUFACTURER'S INSTRUCTIONS REGARDING THE PLACEMENT, MAINTENANCE AND USE OF THE CARBON MONOXIDE ALARMS.


	A wall outlet plug-in style Carbon Monoxide detector.

Most Carbon Monoxide alarms are designed to be mounted on the ceiling or wall, unless the manufacturer instructs otherwise. The ceiling is a common choice for mounting because CO is slightly lighter than air, and is usually associated with warm air, so it tends to rise. In addition, mounting the unit on the ceiling helps to keep it out of reach of tampering, and protects it from unintentional damage. However, some literature suggests that CO will distribute relatively evenly from the floor to the ceiling, so some manufacturers recommend wall mounting their detector, as they may be designed to work in that configuration. Always follow the manufacturer's recommendations, and avoid placing an alarm in areas which the manufacturer warns against. Some of these are listed below. Never paint a CO alarm.

Where to locate a CO alarm(s) depends on the amount of units you decide to purchase for your residence. If installing only a single unit, the Consumer Product Safety Commission recommends placing the unit in the area outside the bedrooms. This is an excellent recommendation for several reasons. Furnaces, a common source of CO, operate more frequently during the night when people are sleeping. During a prolonged period of sleep, you will be unaware of the onset or worsening of any symptoms, and your ability to awaken and be conscious could be significantly degraded because of the long exposure you might suffer unaware during sleep. Depending on the level of CO poisoning your are suffering, an alarm which is sounding distant from where you are sleeping might not be able to wake you in your condition.

If you are going to place multiple alarms (which is recommended), there are several considerations regarding placement, dictated again by the amount of units you are willing to invest in. Consider placing one alarm in each bedroom. One alarm on each floor is another good option. It is a good idea to place an alarm in the vicinity of any gas or oil-burning appliances, although one alarm on each floor should provide adequate coverage, unless you have a larger-than-average sized home.

There are definitely some recommendations on where not to place a unit. Do not place a Carbon Monoxide alarm immediately above or adjacent to any fuel-burning appliances. Normal use of these appliances is sure to emit some CO into the immediate atmosphere, even with proper ventilation. In addition, a short burst of CO may be produced by these appliances on start-up. Follow the manufacturer's suggestions regarding the distance their alarm should be placed from these appliances.

These situations can greatly increase the chance that your CO alarm will give you false indications, or no alarm when CO is actually present.

Another situation you should be aware of is any place that is excessively dusty or dirty. For example, an unfinished basement probably is not the cleanest room in the house, and commonly serves as workshop for the homeowner. Wood dust from sawing and sanding, and airborne particles from spray guns could foul the alarm. These conditions are not just limited to the basement. A remodeling project in a bathroom or bedroom might produce dust from drywall sanding and airborne particles from a paint sprayer.

This should not keep you from placing a CO alarm in the basement, and you probably have one somewhere near the bedroom. You just need to be aware that this condition can cause false indications, or ruin the alarm. It is highly advised that you temporarily remove and protect the CO alarm during a dust condition, and promptly reinstall it when the condition has abated.


Testing your unit and changing the batteries are essential if you expect your CO detector to protect you.

A few last words about Carbon Monoxide alarms. Like any other device they have a finite life and must be replaced. Consult the manufacturer's instructions regarding the operative lifespan of your alarm. Many alarms have an expiration date printed on them.

Don't forget to test your Carbon Monoxide alarm once a month with the unit's test feature. Do not self-test your unit by trying to produce CO with a cigarette, candle, or other similar manner. Besides the danger the open flame presents, you could very easily damage your unit without even knowing it. Some manufacturers recommend gently vacuuming the alarm periodically.

Remember to replace the batteries at least once a year, or per the manufacturer's instructions.

While any Carbon Monoxide incident is serious and should be treated as such, the recommended response is dependent upon whether the source of the problem is obvious or not, and if occupants are feeling ill or not. First and foremost:

TREAT EVERY ACTIVATION OF YOUR CARBON MONOXIDE ALARM AS AN EMERGENCY AND NEVER IGNORE AN ACTIVATION OF YOUR ALARM.

Should your CO alarm activate, immediately begin to assess the situation. Things to think about are:

IF YOUR CARBON MONOXIDE ALARM ACTIVATES AND ANYONE IS EXPERIENCING SYMPTOMS OF POISONING, IMMEDIATELY MOVE OUTSIDE TO FRESH AIR AND ACTIVATE AN EMERGENCY RESPONSE FROM A PHONE OUTSIDE THE HOUSE.

CO alarms are designed to give different warnings so the homeowner can easily differentiate between an actual alarm, and a low-battery situation. If you are receiving a low-battery indication, place fresh batteries in the unit and reset the alarm in accordance with the manufacturer's instructions.

It is quite possible that your are getting an alarm indication and there is no Carbon Monoxide present. Dust, humidity, steam and other conditions can cause false alarms. If you are positive that you have identified a condition causing a false alarm, try to rectify the condition and reset the alarm. You may need to temporarily move the unit to fresh air to help reset it. Consult your owner's manual regarding this.

In some cases, the source of Carbon Monoxide may be obvious. For instance, all your appliances use electric except for the oil-fired furnace, which has been running constantly on a very cold day. Or maybe your power-washer has been running near an open door while you have been cleaning your deck.

Your first step should be to immediately evacuate the house of all occupants, including the pets. If anyone appears to be suffering from CO poisoning, immediately activate an emergency response. Do not use the phone from inside the residence.

THE ABSENCE OF CARBON MONOXIDE POISONING SYMPTOMS DOES NECESSARILY INDICATE THE ABSENCE OF CARBON MONOXIDE.

Turn off the source of the CO, or work to rectify the condition which led to it. Open the doors and windows to ventilate the house. Allow the house to ventilate for some time, then reset the alarm. If the alarm sounds again, continue to ventilate the house until you can get the alarm to cease. If an appliance is causing the CO, do not use it until a qualified professional can service it.

Due to the nature of Carbon Monoxide, it is very likely that you will be unable to identify the origin of the problem. For instance, it is Thanksgiving and all your appliances use natural gas. Your furnace, hot water heater, oven, cook top, and clothes dryer have all been in use periodically throughout the day when your only CO alarm on the second floor activates during dinner. What is the source?

If you get an alarm activation and you are unable to positively identify the problem, immediately evacuate the house of all occupants including the pets. If anyone appears to have symptoms of CO poisoning, immediately active an emergency response. Do not use the phone from inside the residence.

THE ABSENCE OF CARBON MONOXIDE POISONING SYMPTOMS DOES NECESSARILY INDICATE THE ABSENCE OF CARBON MONOXIDE.

Most current literature suggests turning off all appliances and opening doors and windows on your way out to ventilate the house. That is dependent on the type of home you live in. If you live in a single-family home, do not concern yourself with these, except if an operating appliance could become a fire hazard. The reason is, you are going to have to call someone to inspect your house to find the problem. This could be your heating contractor, gas company, or fire department. Ventilating your home will help disperse or remove any concentrations of Carbon Monoxide, making it harder to pinpoint the source during the investigation.

However, should you reside in an apartment, duplex, row house, or other attached home, turn off any appliances and ventilate the house as you exit. In this case, the safety of your neighbors is more important than assisting the investigator in finding the source of the Carbon Monoxide.

Do not return to your home until the problem has been identified, rectified, and the house properly ventilated and all Carbon Monoxide removed.