Do Candles Produce Carbon Monoxide? Safety Facts You Need to Know

A lot of people ask me whether candles give off carbon monoxide. The truth is yes, any open flame produces a little, but the amount from a candle is very small. Here’s what research says and the simple ways to keep candle use safe indoors.

How Carbon Monoxide Forms When Things Burn

Carbon monoxide happens when something burns without getting enough oxygen. Think of it like a campfire that's been smothered - instead of burning cleanly and completely, it starts producing smoke and other unwanted gases. The same principle applies to candles, though on a much smaller scale.

When you light a candle, ideally the flame gets plenty of fresh air and burns the wax completely, turning it into harmless carbon dioxide and water vapor. But sometimes conditions aren't perfect, and that's when you might wonder: do burning candles produce carbon monoxide in amounts that matter?

If you look closely at a candle flame, you'll notice it has different colors. The blue part at the base shows clean burning, while a large yellow or orange flame often means the burning isn't as complete as it could be. This incomplete combustion is what can create small amounts of carbon monoxide.

What Research Tells Us About Candles and Carbon Monoxide

Scientists have actually studied this question, and the results are reassuring. The Consumer Product Safety Commission conducted research that found properly burning candles do produce carbon monoxide, but in very tiny amounts that are generally not harmful during typical use.

So how much carbon monoxide do candles produce exactly? Under normal conditions, a single candle releases about 0.05 to 0.1 parts per million of carbon monoxide per hour. To put that in perspective, that's considered negligible from a health standpoint. The EPA's safety limit is 9 ppm averaged over eight hours, so you'd need quite a few candles burning in a very small, unventilated space to approach concerning levels.

Even when researchers tested multiple candles burning at once in rooms with poor air circulation, the carbon monoxide levels stayed well below dangerous thresholds. This research suggests that for most people using candles normally, carbon monoxide exposure isn't a significant concern.

What Makes Some Candles Produce More Carbon Monoxide

Several things can influence whether your candles burn cleanly or produce more emissions than they should. The size of the wick makes a big difference - if it's too large, the flame gets bigger than it should be and might not get enough oxygen to burn completely. This is why you'll sometimes see candles with flames that seem to dance around or produce black smoke.

The type of wax matters too. Paraffin candles, which are made from petroleum products, tend to burn less cleanly than candles made from natural materials like soy or beeswax. It's not that paraffin candles are dangerous when used properly, but natural waxes generally burn more efficiently.

Ventilation plays a huge role in whether burning candles might produce concerning levels of carbon monoxide. When there's good air circulation, the flame gets fresh oxygen and any combustion byproducts get carried away. In a stuffy room with no air movement, even a small flame can start to struggle.

How you take care of your candles also makes a difference. If you never trim the wick, it gets longer and creates a bigger flame that's more likely to burn inefficiently. Candles that burn for hours without a break can develop carbon buildup that interferes with clean burning.

Different Types of Candles and Their Emissions

Not all candles are created equal when it comes to clean burning. Natural wax candles generally produce fewer emissions than their petroleum-based counterparts. Soy candles burn at relatively low temperatures with smaller, steadier flames, which tends to result in more complete combustion and less carbon monoxide production. They also produce less soot, which is another indicator of cleaner burning.

Beeswax candles are often considered the gold standard for clean burning. They tend to burn very steadily with minimal emissions, and some people even claim they help purify the air (though that's a separate topic from carbon monoxide production). The natural composition of beeswax promotes slower, more controlled burning.

Paraffin candles are the most common type you'll find in stores, and while they do tend to produce slightly higher emissions than natural alternatives, quality paraffin candles with properly sized wicks still burn safely under normal conditions. The key is choosing well-made candles rather than very cheap ones that might have oversized wicks or poor-quality wax.

Specialty candles like gel candles or those with decorative elements can vary widely in how cleanly they burn, depending on their specific composition and design.

Health Considerations and Who Should Be Extra Careful

While the small amounts of carbon monoxide that candles typically produce aren't dangerous for most people, some individuals should be more cautious. People with respiratory conditions like asthma, pregnant women, and young children can be more sensitive to even low levels of carbon monoxide exposure.

The symptoms of carbon monoxide exposure start subtle - headaches, feeling tired or dizzy, and nausea. These are easy to dismiss as stress or being under the weather, which is part of what makes carbon monoxide concerning. While candles alone rarely produce enough to cause these symptoms, they can contribute to overall exposure if you have other sources in your home.

The spaces where we often like to burn candles - bedrooms for relaxation, bathrooms during a bath, or small living areas - can trap any combustion byproducts more easily than larger, airier rooms. This is why ventilation becomes so important when enjoying candles indoors.

If you're pregnant, it's worth being extra cautious about any potential carbon monoxide sources, including candles, since even low levels that don't affect you might impact fetal development.

Simple Ways to Burn Candles Safely

The good news is that enjoying candles safely is pretty straightforward. The most important thing you can do is keep your candle wicks trimmed to about 1/4 inch before each use. This simple step keeps the flame the right size and helps ensure clean burning. Long wicks create large, unstable flames that are more likely to produce unwanted emissions.

Ventilation doesn't have to be complicated - just crack a window or turn on a fan when you're burning candles, especially in smaller rooms. Fresh air helps the flame burn cleanly and carries away any byproducts. You don't need a strong breeze, just some air movement.

When shopping for candles, look for quality over bargain prices. Well-made candles with cotton or wood wicks tend to burn more cleanly than cheaper alternatives with metal-core wicks. Natural wax candles are generally a safer choice, but even good paraffin candles burn fine when made properly.

Never leave candles burning when you're not around to keep an eye on them, and definitely not overnight. Besides the fire risk, unattended candles can develop problems that lead to poor burning. If you notice your candle flame getting very large, flickering a lot, or producing black smoke, blow it out and trim the wick before relighting.

Carbon Monoxide Detectors: Your Safety Backup

Even though candles typically produce very small amounts of carbon monoxide, having detectors in your home is still a smart idea. They protect you from all potential sources, not just candles - things like furnaces, water heaters, and car exhaust are much more likely to cause problems.

Install carbon monoxide detectors on each level of your home and near bedrooms for the best protection. Modern detectors are pretty sophisticated and can even detect low-level exposures over time, which helps you identify if multiple small sources might be adding up to something concerning.

Some newer detectors connect to your smartphone and can send alerts even when you're not home. Others have digital displays that show current carbon monoxide levels in real-time, which can be interesting if you want to monitor how different activities in your home affect air quality.

Remember to test your detectors regularly and replace batteries as needed. A detector that's not working obviously can't protect you.

The Bottom Line on Candles and Carbon Monoxide

So, do candles produce carbon monoxide? Yes, but the amounts are so small that they are not a concern with normal use. The key is to trim your wicks, make sure there is a little ventilation, and never leave a candle burning unattended. With those basics, you can enjoy candles safely in your home. 

Frequently Asked Questions

Can burning too many candles at once cause carbon monoxide poisoning? While multiple candles do produce more carbon monoxide than a single candle, you'd need an unrealistic number burning simultaneously in a very small, unventilated space to reach dangerous levels. Normal home use, even with several candles, remains safe.

Are scented candles more likely to produce carbon monoxide than unscented ones? Scented candles don't necessarily produce more carbon monoxide, but poor-quality scented candles with additives might burn less cleanly. The wick size and wax quality matter more than whether the candle is scented.

How long can I safely burn a candle in a closed room? There's no specific time limit, but it's always best to have some ventilation. Even cracking a door or window slightly provides enough air circulation for safe candle burning in most rooms.

Should I be worried about carbon monoxide if I only burn candles occasionally? Occasional candle use poses virtually no carbon monoxide risk. The small amounts produced dissipate quickly, especially with any air movement in your home.

Can I use my car's carbon monoxide detector to check candle safety? Automotive CO detectors aren't designed for home use and may not be sensitive enough to detect the low levels that household sources produce. Home-specific detectors are more appropriate.

Are there any candles that produce zero carbon monoxide? Any flame-based candle will produce some carbon monoxide, but high-quality natural wax candles with properly sized wicks produce negligible amounts. Only electric alternatives produce zero emissions.

References

1. U.S. Consumer Product Safety Commission. (2019). "Indoor Air Quality and Candle Safety Study." CPSC Office of Hazard Identification and Reduction.
   
   

2. Environmental Protection Agency. (2023). "Carbon Monoxide's Impact on Indoor Air Quality." EPA Indoor Air Quality Guidelines, Publication No. EPA-402-F-23-001.
   
   

3. Centers for Disease Control and Prevention. (2022). "Carbon Monoxide Poisoning Prevention." National Center for Environmental Health, Fact Sheet #96-0001.
   
   

4. National Fire Protection Association. (2021). "Home Candle Safety Research Report." NFPA Fire Analysis and Research Division.
   
   

5. Wallace, L.A., et al. (2018). "Emissions from Consumer Products: Candles, Air Fresheners, and Cleaning Products." Indoor Air Journal, 28(4), 568-580.
   
   

6. American Lung Association. (2020). "Indoor Air Pollutants and Health." Health Education Department Publication.
   
   

7. Derudi, M., et al. (2019). "Emission of air pollutants from scented candles burning in a test chamber." Atmospheric Environment, 85, 257-262.
   
   

8. International Association of Fire Chiefs. (2023). "Residential Fire Safety: Candle Use Guidelines." IAFC Safety Committee Report.