Do Candles Produce Carbon Monoxide? — Explained And Detailed

We love the warmth and ambiance that candles bring. If it’s a scented candle, the fragrance adds to the effect and can work with any room where you place the scented candle. But it is only sensible that we wonder if there are some downsides to this glamorous experience. 

For example, do candles produce carbon monoxide and is it something to worry about?

As with most flames, candles do produce carbon monoxide. The amount of carbon monoxide emitted by a conventional candle is too small to cause any harm. If you are in a ventilated room with an open window, it is near-impossible to be at risk of harmful effects of CO from a candle.

However, there can be a risk if there are too many candles in an unventilated room. So, whether you’re considering mood lighting or ambiance, the smart money is on keeping only a few candles lit. Also, make sure the room is ventilated.

Now that we’ve got the basics covered, let’s get to the details.

Carbon Monoxide From Candles – What It Means For You

Does A Burning Candle Produce Carbon Monoxide? How Candles Produce CO

We know that when something burns, it produces carbon dioxide (CO2). In the case of a candle, the carbon and hydrogen in the wax react with oxygen in the air to produce this gas and water vapor. This holds true for any type of wax.

A tiny portion of this reaction doesn’t go through completely. Some parts of the process/flame will not get enough oxygen, and so in place of carbon dioxide (CO2), the candle will produce carbon monoxide (CO). 

Only a very small amount of CO is produced this way, often something like 0.1% of the entire process. 

To be clear, the production of CO isn’t limited to candles. Most uses of fire will produce a tiny amount of carbon monoxide. For example, if you use a gas cooking stove, or have a fireplace, there will be a tiny amount of CO being released with the reaction.

Keep in mind, CO is flammable and when burnt, it will quickly turn to CO2. In the processes mentioned here, carbon monoxide is produced due to the incomplete burning of the materials, so it doesn’t become carbon dioxide.

a lit candle near a flower

In most cases, this is entirely negligible and non-threatening. If there’s ventilation, you’re unlikely to see any effects of carbon monoxide by burning a candle or a lamp.

This is why burning a candle isn’t an immediate risk of carbon monoxide poisoning or a risk to the health or well-being of someone in the same room. It’s no wonder that candles and lamps have been used for lighting without issue for a huge part of human history.

Can Candles Cause Carbon Monoxide Poisoning?

Gas concentration is measured in PPM, or parts per million. This will be our metric in understanding the CO production from candles and whether it can be dangerous. 

While the exact number can vary depending on the candle, wick, and ventilation, an average burning candle will emit less than 2 ppm of carbon monoxide into a room. This assumes that the candle is in a conventional, well-ventilated room. 

At this concentration, carbon monoxide is far below harmful levels and there is nothing to be worried or concerned about. In fact, in a ventilated room, much of the CO will be swept away by the wind and won’t pose any problem. 

In a small, poorly ventilated or unventilated room, this concentration will be higher, but unlikely to be troublesome. Yet, there will be a risk of CO accumulation, which might eventually push the number higher or into troublesome territory. 

The only practical risk of carbon monoxide with candles can come from lighting multiple candles in a poorly ventilated room. While a single candle emits less than 2 ppm of CO, multiple candles will significantly increase this number. 

If the room is poorly ventilated, the CO can build up to concerning levels. Again, if it’s a well-ventilated room, the carbon monoxide won’t be a problem. 

One scenario worth considering here would be using candles to heat a room. As it was noted in the linked article, using candles as a heat source is not a good idea. To heat a room with candles, you would reduce ventilation and light about 20 candles. 

With so many candles burning and producing CO, the effect can be significant and there would be worrisome levels of carbon monoxide in a room.

Overall, if you’re burning a candle in a well-ventilated room (as most people do), there is no risk or threat of carbon monoxide poisoning from the candle. 

Do Scented Candles Emit Carbon Monoxide?

Scented candles are often seen as being somewhat therapeutic and adding another dimension to the ambiance of candle light with their scents. But do these candles produce carbon monoxide?

Where there is a flame, there is potential for carbon monoxide. Scented candles emit some CO when they’re burnt. 

The amount of carbon monoxide produced by scented candles is the same as conventional candles. So, an average scented candle will produce less than 2 ppm of CO when burnt.

While there are different kinds of waxes, many of which claim to burn clean, the average CO produced remains consistent throughout. However, there is merit to clean-burning waxes in terms of other byproducts like VOCs.

Can A Candle Set Off A Carbon Monoxide Detector?

a woman holding a candle in an apparently smoky room

It is nearly impossible for a candle to set off a carbon monoxide detector. The CO produced by the candles is too low for a detector to raise an alarm. 

Most carbon monoxide detectors get into action near 50 ppm of CO, though they may give it some time before sounding an alarm. A concentration of 150 ppm of CO will immediately set off a carbon monoxide detector.

As candles produce less than 2 ppm of CO, the chances of setting off a CO detector are practically non-existent. 

On Carbon Monoxide Poisoning And What Makes It Dangerous

A Quick Note On Carbon Dioxide

Do candles give off CO2 (carbon dioxide)? The process of candle burning employs a chemical reaction where the carbon and hydrogen in the wax react with oxygen in the air to produce carbon dioxide and water vapor. So, when burnt, any candle will give off CO2.

While carbon dioxide is not breathable, the chances of toxicity from the gas are rare. 

Symptoms of CO2 poisoning usually show up around 30,000 ppm concentration. Although it isn’t directly dangerous, it can cause headaches and dizziness. Things get more dangerous at 40,000 ppm. 

It is at 80,000 ppm that CO2 becomes life-threatening. This is an extremely unlikely scenario for an average person in day-to-day life. Even getting exposed to 30,000-40,000 ppm carbon dioxide is an unlikely scenario. 

Besides, should someone encounter this problem, the headache and dizziness become a problem and would encourage them to move away. 

There is some scientific evidence that suggests that animals (including humans) have some sensory detection of oxygen and carbon dioxide. This might play a role in helping people get out of the way in case they’re at risk of CO2 poisoning.

Carbon Monoxide Is Very Dangerous And Sinister

Carbon Monoxide (CO) is very different from carbon dioxide. It is commonly called the “silent killer”. The gas is colorless, odorless, tasteless, and non-irritating. It means the early signs of poisoning might be entirely ignored or be otherwise difficult to detect.

According to EPA and OSHA, the permissible exposure limit to CO is 50 ppm over an eight-hour period. For comparison, this similar limit for CO2 is 5000 ppm. 

So what makes CO so much more dangerous as compared to CO2?

Carbon Monoxide (CO) binds with the hemoglobin (Hb) in the blood. Hemoglobin is the primary carrier of oxygen in the body and is responsible for delivering oxygen to various parts of the body. 

Carbon Monoxide forms a more stable bond with Hb, denying access to oxygen and thus preventing the body and organs from getting the oxygen it needs. It can take a lot of time for CO to clear out of the blood (Hb), which means that the longer you’re in a CO-rich environment, the more dangerous it gets.

And since CO isn’t easily detected without specific equipment, things can get very dangerous for a person, without them ever knowing what’s going on. 

There is a somewhat famous story on reddit where a user posted a question to their legal advice subreddit. To the user, it felt like someone (most likely their landlord) was leaving weird post-it notes in their home. There was no proof and the cameras (webcam) they set up caught nothing. 

Someone on the forum thought this was all weird and suggested that the user recheck their CO monitor or get a new one, just to be safe. Sure enough, the original poster of the question checked in again with an update. The poster mentioned that he got a CO monitor and it read 100 ppm. 

This person was getting CO poisoning and doing stuff without even remembering it! What he thought was a stalker was actually the actions of this person himself, which he forgot within hours or a day. 

While this story has a happy ending and the person is okay, it underlines how dangerous CO poisoning is. Although they were lucky the CO concentration wasn’t higher, as it can be life-threatening.

5 Points And Steps To Reduce The Risk Of CO Poisoning

a woman with a candle

As we know, candles produce carbon monoxide but the amount is too low to be of concern in a ventilated room. Most CO detectors in homes are set to watch out for risks coming from a home’s heating system or cooking gas. 

So while the risk of CO poisoning from a candle is minimal, it pays to be prepared and take adequate precautions. Also note, the points mentioned here are candle-specific, though a few can be applicable in a general scenario as well. 

1. Light Only A Few Candles At A Time

A single candle is unlikely to produce enough CO to be troublesome. However, there might be occasions where someone decides to light multiple candles in a room. While this is good for ambiance, it can and will affect air quality. 

Avoid lighting too many candles in a room. If you do light several candles, ensure proper ventilation. 

2. Keep Your House Well-Ventilated

Proper ventilation ensures that there won’t be a CO buildup over time inside your house. While we’re specifically talking about CO here, good ventilation is important for a home because of several aspects.

Fresh air will give your home good air quality and make it feel a lot more pleasant. And all you have to do is open a window!

In cases where opening a window may not be possible, use a ventilation fan or exhaust fan to ensure good air quality for your home. Even using the bathroom exhaust fan can be of some help.

3. Put Out Candles After A Few Hours

Generally, it is recommended not to burn a candle for more than four hours. This helps with the life and maintenance of the candle. It also helps reduce exposure to chemicals and by-products produced by burning candles. 

As such, you would also reduce exposure to carbon monoxide by putting out the candle.

One point to note here is that if you simply blow out a candle, you’ll notice it produces a lot of smoke. Much of this smoke consists of PM 2.5 particles that will adversely affect the air quality of the room. 

If you’re fond of burning candles, it’s better to put the candle out with better methods like a wick dipper, candle snuffer, or even using the lid where possible.

4. Get A Carbon Monoxide Detector And Alarm

Every home should have a competent CO detector and alarm. Check it regularly and keep it well-maintained. As the name suggests, the device keeps tabs on CO concentration in your home and will sound an alarm should it reach dangerous levels.

For most homes, CO detectors are geared towards keeping tabs on carbon monoxide levels from cooking gas or heating. These detectors remain useful if you’re concerned about CO levels in the home after lighting candles.

5. Be Vigilant

Even if you’ve taken all precautions, there is no substitute for being vigilant. There are many sources of CO in a home. These include cooking gas, or even gas or fuel-based heating systems, including space heaters.

If you feel symptoms like nausea, headache, or breathlessness, immediately extinguish the candle or any other source of carbon monoxide in your home. The same might also apply if you feel that the air is getting too stuffy.

Listen to your body and your instincts. If necessary, get another CO detector to ensure that there is no malfunction in an existing CO detector.

Stay Safe When Lighting Candles

Now that we’ve discussed it at length, it is safe to say that all types of candles do produce carbon monoxide. However, the amount of CO a candle emits is tiny and doesn’t pose a risk. 

Most candle lovers generally use a single candle in a ventilated room. In this scenario, there is no practical risk of CO poisoning from a candle.

That said, using multiple candles in a room with poor or no ventilation can cause the CO levels in the room to rise to worrying levels.

In an average home, many activities like cooking and heating can produce carbon monoxide. Candles produce a tiny, but measurable amount of carbon monoxide. 

Even though the risk is low, it’s best to take adequate precautions. Keeping a house well-ventilated and using a CO detector should help ensure good air quality for your home.