Carbon Monoxide & Your Home: What You Need to Know

We all want our homes to be safe, comfortable places where we can relax without worry. But keeping safety levels high requires some due diligence – and it starts with knowing the risks and how to reduce them.

One of the biggest risks in the home is carbon monoxide poisoning.

According to the Center for Disease Control (CDC), at least 430 people die in the U.S. every year from accidental CO poisoning, and around 50,000 Americans visit the ER each year because of exposure to carbon monoxide.

Data from the U.S. Consumer Product Safety Commission show that heating systems were associated with the second largest percentage of non-fire CO poisoning deaths in 2017, and that most CO deaths occurred during the colder months of the year.

So, what is carbon monoxide, how does it get in your home, how does it affect the body, and what can you do to protect yourself and your family? We’re going to cover it all right here. Let’s get started…

What Is Carbon Monoxide?

Carbon monoxide is a gas that’s created because of the incomplete burning of fuel. Anytime you burn something incompletely – be it coal, charcoal, LP gas, natural gas, oil, or wood – carbon monoxide is created during the combustion process. And the truth is, complete combustion almost never occurs. There’s always some kind of off-gassing when burning fuel.

Carbon monoxide is the second leading cause of poisoning in the home, and it’s colorless, odorless, and highly toxic, which makes this ‘silent killer’ particularly worrisome.

What Does Carbon Monoxide Do to You?

The human body is strange, especially when it comes to how it interacts with carbon monoxide. You’d think that the body would reject this deadly gas, but it doesn’t – it embraces it.

Like a hungry teenager given a choice between a plate of raw brussels sprouts and a sizzling pepperoni pizza with extra cheese, it’s not even a contest. When given the choice between binding to oxygen or carbon monoxide in the air, your blood cells choose carbon monoxide every time. To your body, the carbon monoxide is the pepperoni pizza, the obvious choice.

The difference here is that a little pepperoni pizza isn’t going to hurt you – a little carbon monoxide can.

The CO molecules that you inhale attach to the red blood cells in your body and hitch a ride to your lungs. Over time, the CO molecules displace the oxygen in your blood and prevent oxygen from being delivered to your organs. This is called carbon monoxide poisoning and it harms and kills people every year.

How Long Does It Take to Get Carbon Monoxide Poisoning & What Are the Signs?

It doesn’t take long for carbon monoxide to poison you. Depending on the concentration of CO in the air (among other factors like age and overall health), carbon monoxide can kill a person in as little as five minutes.

The problem is that – because it’s colorless and odorless – you can be exposed and at risk of CO poisoning and not even know it. And it gets even more complicated…

All the symptoms of carbon monoxide are similar to the ailments associated with the flu, and because CO poisoning mostly happens in the winter months when flu and other nasty bugs are common, many folks just assume they’re coming down with a bug.

Initial signs of CO poisoning include things like:

  • Headache
  • Nausea
  • Sleepiness/Lethargy
  • Confusion
  • Dizziness
  • Chest Pain

When someone isn’t feeling well, the inclination is to lay down and rest a little. But if the individual remains exposed to carbon monoxide when they head to bed, they may never wake up. This deadly gas slowly anesthetizes people – and it does it without fanfare or obvious signs.

Can Small Amounts of Carbon Monoxide Hurt You?

Yes, even small amounts of exposure over prolonged periods can cause harm and endanger your health. We now know that low-level exposure to carbon monoxide can cause permanent organ and brain damage, especially in infants, the elderly, and those with anemia, respiratory problems, or heart disease.

Low-level exposure may also cause prolonged flu-like symptoms, chronic fatigue, or generalized depression. So, if you have any of these symptoms and you can’t seem to shake them, please see your physician.

Do Fireplaces Give Off Carbon Monoxide? Can You Get CO Poisoning from a Chimney? What Other Appliances Can Give Off Carbon Monoxide?

‘Can you get carbon monoxide poisoning from a chimney?’ ‘Do wood-burning fireplaces produce carbon monoxide?’ ‘Can leaky furnaces cause CO poisoning?’

These are questions we hear a lot. The answer to all three questions is YES.

Basically, any appliance in your home that burns fuel – be that gas, wood, pellet, or oil – has the potential to send carbon monoxide into your home. The trouble starts when the home isn’t well ventilated OR when the venting system attached to these appliances fails to do its job.

For example, if a chimney is blocked and the carbon monoxide produced by the fireplace can’t swiftly exit through the chimney top, it will flow back into your home.

Or, if there’s lint buildup inside the dryer vent and that lint prevents the CO from exiting the home, you can have a backflow of carbon monoxide.

In both scenarios, a simple problem– one that could easily be prevented with a professional chimney or dryer vent cleaning – could cause carbon monoxide poisoning.

So, what appliances do you need to be concerned about and routinely checking?

Most people know that cars put out carbon monoxide, but there are a lot of common appliances in our homes that we don’t think about when we think of carbon monoxide.

For example, carbon monoxide is put out by:

  • Fireplaces
  • Gas & oil furnaces
  • Gas water heaters
  • Gas stoves
  • Gas dryers

While all these appliances are relatively safe when well maintained and used as designed, neglect, damage, and other issues can lead to an increase in carbon monoxide risk.

Potential issues include:

  • An air-tight home/inadequate combustion air
  • A blocked chimney
  • Poor draft
  • A missing or damaged flue liner
  • A liner mismatch (wrong size or material for the appliance and fuel type)
  • A blocked, lint-logged dryer vent

The best way to protect yourself against carbon monoxide hazards with these appliances is to have each professionally inspected on an annual basis. The appliances themselves should be inspected, as well as their venting systems.

After all, even the most efficient appliance can contribute to a CO problem if the venting system attached to it isn’t clean and in good working order. Many chimney sweeps inspect fireplace flues, stove pipe, furnace flues, and dryer vents – and you can quickly find a qualified pro in your area right here.

Why Is Carbon Monoxide Poisoning on the Rise?

Why is carbon monoxide poisoning – primarily linked to home heating systems – on the rise, when most of these systems have been around and safely used for years?

Well, there are a few reasons:

1. Modern homes are more air-tight than homes of old. Homeowners are aware of the cost of heating drafty homes, and many have taken steps to seal up windows, doors, and other areas of air filtration. The trouble is that a tighter home means less fresh air can enter the home and less polluted and stale air can exit it. And when furnaces and boilers are starved of the oxygen needed to burn fuels completely, carbon monoxide is produced.

2. Manufacturers are now designing home heating appliances with greater efficiency to reduce fuel costs, conserve natural resources, and decrease environmental pollution. But these new high-efficiency gas and oil furnaces, when vented into existing chimney flues, often don’t perform at optimal levels. This decrease in performance increases the chances that toxic gases like CO will enter the living space.

3. Many homeowners aren’t aware of the upkeep required for venting systems. Damaged, deteriorating, or mismatched liners can cause issues with carbon monoxide, as can soot buildup, debris-clogged chimneys, and bird and animal nests. Because of a lack of education around routine inspections and cleanings, many homeowners neglect these systems until obvious problems arise. Many of these issues can force carbon monoxide into the living spaces of your home – either as a one-time high-level exposure situation or with smaller amounts over a longer period of time.

How Do You Check for Carbon Monoxide? Can You Detect CO Without a Detector?

As we discussed earlier, carbon monoxide is colorless, odorless, and tasteless. So, when it comes to knowing if you have a carbon monoxide leak in your home, you can’t rely on your senses the same way you would with smoke or a propane leak.

The most accurate and easiest way to find out if you have a carbon monoxide issue in your home is to install CO detectors and keep the batteries fresh. A CO detector will alert you to a problem if there is one.

That said, there are some things you can be on the lookout for that could signal a problem with carbon monoxide, like:

  • Burning smells, exhaust smells, or other odors that just don’t seem right
  • Issues with your pilot light
  • Changes of performance with your appliance
  • Issues with draft in your chimney
  • Condensation on your appliance or on windows in the area
  • Yellow staining on or near the appliance (or in the room the appliance is in)

If you suspect a carbon monoxide leak with your heating appliance, you should immediately stop using the system, leave your home, and call 911. Don’t open windows or leave any doors open when you leave. If you do, it could make it more difficult for the fire department to determine the source of the carbon monoxide.

If they confirm an issue with your furnace chimney or fireplace, once they’ve cleared you to re-enter your home, schedule an inspection with a CSIA-Certified Chimney Sweep®. You can find one right here. If the issue is with your dryer vents, search for a Certified Dryer Exhaust Technician (C-DET)® in your area right here.

How Can I Avoid Carbon Monoxide Hazards?

We now know that most carbon monoxide threats arise in the winter when our heating appliances are in use. We also know that carbon monoxide mostly kills people in their sleep.

With these two facts in mind, there are two things you can do to avoid carbon monoxide hazards and keep your family protected:

#1 Make sure your heating appliances (furnaces, boilers, fireplaces, etc.) and their venting systems are inspected by a CSIA-Certified Chimney Sweep® every year.

Heating appliances and venting systems that are properly installed, properly maintained, properly sized, routinely cleaned, and used as intended are far less likely to be a safety and health threat.

In fact, many government agencies in the United States now recognize the importance of annual heating system inspections and maintenance and the role these services have in preventing carbon monoxide poisoning.

The U.S. Consumer Product Safety Commission, the U.S. Environmental Protection Agency (EPA), the National Fire Protection Association (NFPA), and the American Lung Association (ALA) all encourage the regular maintenance of home heating systems and their chimneys to keep ‘the silent killer’ at bay.

And the truth is, there are many benefits to annual inspections and routine maintenance – not just protection against carbon monoxide…

A well-tuned furnace or boiler will operate efficiently and result in a warm and comfortable home. Likewise, a well-maintained and properly vented fireplace will provide many nights of comfort and calm.

So, protect your family and keep your home comfortable and efficient by scheduling an annual chimney inspection with a CSIA-Certified Chimney Sweep® (and taking care of sweepings and repairs as needed).

CSIA-Certified Chimney Sweeps® are trained to inspect, clean, and maintain the chimneys and venting systems of furnaces, boilers, water heaters, fireplaces, inserts, and stoves. Plus, many sweeps are also Certified Dryer Exhaust Technicians (C-DET)®, which means they can inspect, clean, and repair dryer vents as well. With one call, you can take care of them all.

Easy. The way it should be.

#2 Invest in CO detectors for your home.

Carbon monoxide detectors save lives. Period. These affordable devices can detect CO in the air before it reaches lethal levels and alert homeowners before it’s too late.

How do they work? Well, there are a few different types.

  • One type works by detecting changes in electrical currents. When the electronic sensor on the carbon monoxide detector comes into contact with CO, the change in current triggers the alarm.
  • One type works by monitoring electrical resistance. The semiconductor in the device detects the lowering of electrical resistance caused by CO and triggers the alarm.
  • One type works using a biometric sensor. The sensor changes color when CO is present, and that color change is what triggers the alarm.

Although they all work differently, they all work, and they’re all held to the same minimum standards – so you don’t need to worry about choosing one over another. You don’t even have to spend a lot of money unless you wanted extra features – and you may.

For example, if you have pets or elderly folks at home, you may want to invest in a smart CO detector that alerts your phone if it detects carbon monoxide. That way you could alert the fire department and head home or send a neighbor to get pets and the elderly (who may not hear the alarm) out of the home as quickly as possible.

Otherwise, any carbon monoxide detector will do just fine.

Do You Need a Carbon Monoxide Detector for a Wood-burning Fireplace?

The incomplete burning of any fuel, including wood, creates carbon monoxide. So, even if you have a wood-burning fireplace and don’t have any gas appliances in your home, it’s wise to invest in carbon monoxide detectors for your home.

How Many Carbon Monoxide Detectors Should You Have in the Home (and Where Should You Have Them)?

The number of carbon monoxide detectors you’ll need for your home depends on the size and layout of your home. Placement of carbon monoxide detectors follows that of smoke detectors, so you should plan on having one on every level of your home and outside of all sleeping areas. It’s also a good idea to have one near your garage.

The good news is that there are many combination smoke/carbon monoxide detectors on the market, so you can buy a single detector for each area to protect you against both smoke/fires and carbon monoxide.

Note: Be sure to check local codes. You may be required to have a smoke/carbon monoxide detector in every bedroom of the home.

How Often Do Carbon Monoxide Detectors Need to Be Changed?

Typically, carbon monoxide detectors last between 5-7 years. There should be some kind of guidance around lifespan on the packaging when you purchase your device.

Unless the instructions tell you otherwise, you should plan on changing the batteries every 6 months or so. One easy way to keep track of when the batteries should be swapped out is to do it when you change the clocks for Daylight Savings.

And of course, it’s always wise to test your carbon monoxide and smoke detectors on a monthly basis – they won’t do you any good if they’re not working!

Protecting Your Family Doesn’t Have to Be Hard – Now You Know How

Carbon monoxide is a risk, but it doesn’t have to be a worry in your home. Hopefully, now you feel knowledgeable and empowered to keep your family protected. A little maintenance and proactive effort are all it takes to greatly reduce the chances of being exposed to carbon monoxide. So, invest in quality CO detectors and make annual chimney inspections a priority. And remember, finding a qualified professional to do venting inspections, cleanings, or repairs is easy – search your zip code right here.

Psst! Don’t forget to download your CO Cheat Sheet. You can put it on your fridge or add it to your home maintenance file, so you never forget what you need to do – and when – to reduce your risk of carbon monoxide poisoning. Grab it right here.


In compiling our Homeowner Resources page, we wanted to be sure to include information on The Facts About Chimney Fires.