Which candles are safe? Could burning paraffin candles do more harm than good? Can it be toxic? I started to wonder about those things after purchasing a bag of paraffin tea light candles. Some websites suggest that paraffin candles are no good for you; however, I was not convinced based on their sources. Because of that, I have decided to examine which candles are safe to use. To my surprise, I found out that it’s not just about the candle Itself but also about the way, you use it! That there are easy ways to limit the possibly harmful emissions from a candle.
Before I begin, I want to state that I am not a chemist, scientist, etc. I read many free scientific (published) articles and other materials that I found on the internet and tried to understand which candles are safe.
Ok, now, let’s get a closer look at a candle. Do you know why a candle burns?
How does a candle work
Let’s just shortly go over the process of how a candle works to understand the following findings better. To light a candle, you need three components:
- Energy (initially introduced by a match or a lighter)
When a candle is lit (through the energy from a match o a lighter), the fire melts the wax around the wick. The wax is transferred by capillary action upwards through the wick and vaporizes. The wax vapor represents fuel for the flame, thanks to which you can enjoy your candle.
It is good to realize that flame behavior differs and can be divided into three stages :
- Normal burn – stable flame
- Sooting – larger flickering flame with black smoke
- Smoldering – white smoke after extinguishing the flame
Those stages differ in the combustion process. During normal burning, the wax is burned almost entirely. If complete combustion took place, the flame would be blue, and it wouldn’t produce any pure carbon monoxide (a poisonous gas) or soot (carbon) . Incomplete combustion of the wax (in general of carbon-containing fuels) happens due to an insufficient amount of oxygen and creates an orange flame. It generates pure carbon monoxide (a poisonous gas) and may also produce soot (carbon), i.e., the smoke that you see above the flame or the black residue that deposits on your walls, furniture, etc. . Further, in the post, I will talk about the fact, that during sooting and smoldering stage the amount of harmful substances emitted to the air is significantly larger than during normal burning ,  and that it can be easily eliminated simply by changing the way you use your candles.
Ok, those are the basics. Now let’s look at the candle materials and their health effects.
Elements of a candle
There are two elements, that should be taken into consideration when buying a candle. The wick and the wax.
The wick is made of an absorbent material, which transfers the melted wax upwards; hence, it brings the fuel to the flame. Wicks can be made out of different materials, such as:
- Metal (metal-core)
When buying a candle, look out for metal wires in the wick. In some candles, the wick contains a metal-core which can be made out of lead, zinc, tin, etc. The metal-core is added to the wick to keep it standing straight when the wax starts to melt. In a study, carried out in Michigan by Nriagu et al. , it has been established, that burning 4 candles with metal-core for 2 hours can cause airborne lead concentrations which can be harmful to human health. Not only the harmful substance can be inhaled, but also children can get exposed to lead from deposited candle fumes on the floor, furniture, walls, etc. if they put their exposed hands to their mouths. Good news is, that in the U.S. metal-cored wicks, that contain more than 0.06 % lead by weight in the metal and candles with such wicks, have been banned by the Consumer Product Safety Commission (effective on October 15, 2003). However, if you are buying a candle outside the U.S., and you don’t know, if such a ban is effective there, it’s a safe bet to pick a candle without a metal core.
When in doubt, don’t buy candles with wires in the wick.
The wax represents fuel for the flame. When the wax is melted by the heat of the flame, it transfers upwards through the absorbent wick by capillary action, the heat transforms the liquid wax into vapor, which is then burned and maintains the flame.
Candle wax can be made out of:
- Bayberry Wax
- Palm Wax
- Paraffin Wax
- Soy Wax
And here comes the question, can some types of wax pose a risk to our health? To answer it I have searched through 10+ scientific articles. My initial expectation was that the “natural” alternatives, like beeswax, soy wax, etc. will have much better results than paraffin wax. To my surprise, the results were not that obvious.
Which type of wax should I choose?
It turns out that there is not a significant difference between the paraffin wax, beeswax, or stearin regarding health threats. Based on the articles I have examined, it seems that the primary health opposing threat is not the wax type, but:
- The quality of the wax itself
- The added substances, like fragrances and coloring
If you want to read the detailed explanation of these findings, keep reading. If you want to get to the conclusion and find out, what can you do, to limit toxic fumes from your candles, click HERE.
In the study carried out by Lau et al. , they have analyzed the exhaust fumes of candles made from different waxes and finishing materials. It was found, that the concentration of analyzed compounds (PCDD/PCDF – Polychlorinated dibenzo-p-dioxins/dibenzofurans, benzo(a)pyrene, and some VOC ), even in the case of simultaneously burning multiple candles in a small room, was lower than 1% of tolerable limit values. Also through toxicological risk assessment, carried out by Schwindt et al. , it was found that emissions of candles made out of paraffin, beeswax, and stearine (without paint or decorative elements) are much lower than administrative limitation values; hence it was stated that they don’t pose a toxicological risk for human health. This was also confirmed under a worst-case scenario. Even though you would find, that paraffin candles had slightly higher emission values for PCDD/PCDF followed by stearin and beeswax, in the case of PAH paraffin waxes emissions of some compounds were higher but some lower, then those from beeswax and stearine. The authors of the article state that those differences are not significant.
The study carried out by Derudi et al.  seems to indicate that emissions of some harmful substances (BTEX and PAHs) are determined by the kind of raw material (only different types of pure paraffin wax were tested). This means that you can find two pure paraffin candles that will emit a different amount of pollutants. Unfortunately, I haven’t found any such comparison regarding other wax types.
Fragrances & coloring
As you might have noticed, Schwindt et al.  have tested candles without color or decorative elements. This is an important fact, since Derudi et al.  found, not only that the purity of raw materials of the candle, i.e., the wax quality, can lead to important differences in the emission of harmful substances (VOC – volatile organic compounds and PAH – polycyclic aromatic hydrocarbons), but also additives in the candle. Derudi et al.  tested scented and pure paraffin candles, and found out, that harmful aldehydes emission (mainly of formaldehyde) were above the detection limit only in the scented, colored candles, hence it was concluded, that such emissions are mainly related to the fragrances in the candle. Even though formaldehyde concentrations were well below the considered standards , the authors noted, that further toxicological study should be performed to evaluate the collected data. Nearly no emissions of aldehydes have been detected from pure paraffin candles.
Based on this research it seems that to answer the question “Which candles are safe” the focus should not be on which type of wax you choose (paraffin wax, stearine, beeswax) but on the quality of the wax and the additives. I know, you are probably thinking, how am I supposed to know, if a candle has a high-quality wax? Unfortunately, I am not able to answer that question. Also, I have not found a similar study on other wax types, so it’s hard to say if the quality of the wax matters only in the case of paraffin wax or also different types of wax. However, it is important to remember, that other studies have shown, that candles without coloring and fragrance don’t pose a health risk regardless of the wax type, that the emissions were lower than administrative limits. This brings me to additives, which, in my opinion, are the ingredients to look at. Coloring and fragrances are often synthetic and can be the source of aldehyde emissions. Since on many candles, you won’t be able to tell, if the colorant or fragrance is toxic, the easiest way is to buy unscented candles without coloring and use a different approach to add fragrance to your room.
Don’t buy candles with synthetic fragrances and coloring.
You may cause most of the pollution!
Fine et al.  found out that burning candle emissions of fine particles (air pollutants) also differ depending on the burning stage (combustion behavior). The vast majority of fine particle emissions is generated during sooting and smoldering stages. Zhishi et al.  stated that most of the time a few seconds of smoldering generated more fine particulate matter (air pollutants) than during the whole period of normal burning (for the explanation of all burning stages click HERE). Fortunately, those two stages can be easily controlled . Let’s get a closer look at them to learn how to avoid them.
Sooting (larger flickering flame with black smoke) is usually caused by a wrong wick position or airflow that disturbs the flame. It can be a draft, people walking next to the candle, simply put the usual movement in the house. Soot consists of fine black elemental carbon particles, which can, among others, darken interior elements . Fortunately, you can limit the disturbance of the flame simply by putting candles in places, where there isn’t a substantial air disturbance (e.g., air conditioning, opened window) and where there is not a large amount of walking. To my surprise, lighting candles in a glass container will not help since it seems to produce excessive soot . Another way to control this process is a better wick design , this can be adjusted by trimming the wick every now and then to 1/8 inches (0,3 cm) above the wax. For this purpose, you can buy a specialized wick trimmer or use traditional scissors. Be sure, to cut the wick when the wax is totally dry. If the wick would fall into the melted wax pool, it would probably leave black marks in the wax.
Smoldering (white smoke after extinguishing the flame) appears after you extinguish the flame. A smoldering wick generates fine particles (white smoke) that mainly consist of organic compounds . During smoldering, a candle can generate more particulate matter than during several hours of normal burning! This phenomenon can be, however, easily solved by simply changing the way you extinguish candles ! If you extinguish a candle by simply blowing it out or with an inverted cup, it will cause significant smoldering . To find out how to properly extinguish a candle, keep reading.
How to properly extinguish a candle
To extinguish a candle with none or almost no smoldering dip the wick into the wax pool using some nonburning object, like, e.g., a metal hook from a coat hanger. When the fire extinguishes, straighten the wick back again.
Benefits of the dipping method
- None or almost no smoldering.
- None or almost no unpleasant odor.
- The wick will be covered by wax, which will fasten the time in which you will light the candle again (the “fuel” will be right next to the flame). For similar findings, see Zhishi et al. .
Below you can find a short video, where the dipping method is demonstrated and also compared to the traditional blowing out a candle.
The most important thing
Since this post is about candles, it seems necessary to point out two important things, that you should ALWAYS do, irrespectively to which candle you buy.
- Never leave burning candles unattended.
- Always ventilate well the room, in which you have been burning any number of candles. Every candle emits at least pure carbon monoxide, which is a poisonous gas and may also produce carbon (soot). Those are byproducts of combustions chemical reaction. Of course, also other compounds might be emitted from the candle. To put it simply, If you would burn many candles, regardless of which kind, in a room and would not ventilate it properly, it poses a significant health risk!
Candle manufacturing represents a multi-billion industry, which of course wants to sell as many candles as it is possible. There isn’t a regulation that requires manufacturers to state if a candle can pose a risk to human health. Even though some candles have better ingredients and some worse, unfortunately, it is hard for consumers to find out which candle might be toxic. Some sources streamline that problem and say, only beeswax or soy wax is ok, and that paraffin wax is toxic. I can not agree with those statements. Based on my research, if we will buy and use candles, and keep in mind 8 tips written below, we should eliminate potential health threats and enjoy candles safely.
8 tips for safe candle burning
- Don’t use candles with metal wires in the wick if you are not sure if lead is banned from candles or wicks in your country.
Note: The U.S. has banned lead (above 0.06 %) in 2003.2. If you choose paraffin wax, If possible, try to buy candles with a high-quality wax.
3. Buy candles with pure wax content (without fragrances, coloring, or decoration).
4. Place the candle in an area without air disturbance to limit sooting (e.g., air-conditioning, draft, people walking).
5. Every now and then cut the wick to 1/8 inches (0,3 cm) to limit sooting.
6. Extinguish a candle by dipping the wick with a nonburning object (e.g., a metal hook from a coat hanger) into the melted wax and raising it back up to limit smoldering.
And most important
7. Don’t leave burning candles unattended!
8. Always ventilate rooms in which you have been burning candles!
I hope that this post was helpful to you and that you have learned something new. For those of you, who want to examine this topic on your own, I have prepared a list of references to articles I have reviewed. I will be happy to hear what do you think about this topic in the comments below.
 Fine, P. & Cass, R., G., Simoneit, B. “Characterization of Fine Particle Emissions from Burning Church Candles”. Environmental Science and Technology. 1999. 33. 2352-2362. 10.1021/es981039v. Link to the article
 Krause, D. “Black Soot Deposition: How It Impacts IAQ”. RSES Journal. February 2001. Link to the article
 Nriagu, J., O., Kim, M.-J. “Emissions of Lead and Zinc from Candles with Metal-Core Wicks.” Science of The Total Environment. 2000. 250. 1-3. 37-41. Link to the article
 Consumer Product Safety Commission. “Metal-Cored Candlewicks Containing Lead and Candles With Such Wicks”. 04/18/2003. Retrieved 03/12/2019. Link to the article
 Lau, C., Fiedler, H., Hutzinger, O., Schwind, K.-H., Hosseinpour J. “Levels of selected organic compounds in materials for candle production and human exposure to candle emissions”. 1997. 34. 5-7. 1623-1630. Link to the article
 Schwind, K.-H., Hosseinpour, J., Fiedler, H., Lau, Ch., Hutzinger, O. “Bestimmung und Bewertung der Emissionen von PCDD/PCDF, PAK und kurzkettigen Aldehyden in den Brandgasen von Kerzen”. Environmental Sciences Europe (Umweltwissenschaften und Schadstoff-Forschungx). 1994. 6. 5. 243-246. Link to the original article I Linkt to the article in English
 Derudi, M., Gelosa, S., Sliepcevich, A., Cattaneo, A., Rota, R., Cavallo, D., Nano, G. “Emissions of air pollutants from scented candles burning in a test chamber”. Atmospheric Environment. 2012. 55. 257-262. Link to the article
 Derudi, M., Gelosa, S., Sliepcevich, A., Cattaneo, A., Cavallo D., Rota, R., Nano, G. “Emission of air pollutants from burning candles with different composition in indoor environments”. Environmental Science and Pollution Research. 2014. 21. 6. 4320-4330. Link to the article
 Guo, Z., Mosley, R., McBrian, J., Fortmann, R. “Fine Particulate Matter Emissions from Candles”. 2000. Link to the article