Can a Candle Clean the Air?

If you were to draw a venn diagram of my interests and the more crunchy granola all natural crowd, there would be a lot of overlap. We both care deeply about taking care of our planet, each other, and ourselves, including what we put in and on our bodies. Targeted online advertising recognizes this, and shows me things that sometimes make my eyes roll. Because while all of the above is true, I’m also have a degree in biology and a deep belief in science and data.

So when I see claims like, “Beeswax candles clean the air,” well, it I get a little bit twitchy. Clean the air how? It makes it sound like the candle is somehow removing something found in the air, therefore leaving the air more pure.

According to ebeehoney.com, when beeswax candles burn, they produce negative ions. These negative ions attach to positive ions (like dust, pollen, mold, odor, toxins) floating in the air and in this process cleans the air. Sounds great, right? But where is the evidence that this is the case. Where are the scientific studies showing that 1) beeswax does indeed produce negative ions and other types of candles don’t and 2) that these negative ions do indeed attract positive ion irritants in the air and burn them up and 3) that burning these things up and the resulting emissions isn’t worse for air quality than where we started. 4) assuming they DO clean the air of pollutants, exactly how fast does that happen. How long would you need to burn one candle to “clean” one 8 x 12 x 8 room, for example?

Fire = combustion. Combustion is defined as the rapid chemical combination of a substance with oxygen, involving the production of heat and light. Incomplete combustion (which is typical in our normal 21% oxygen atmosphere), whether you’re talking about a gasoline engine or a candle, tends to result in soot (ie carbon residue) and VOC’s (volatile organic compounds) being released. Candles do tend to burn quite hot, so combustion is more complete and emissions are generally quite small. But soot and VOC’s are released never the less. So we know for sure that candles, beeswax or otherwise, are ADDING stuff to the air as they burn.

This nice study by the European Candle Association, tested candle emissions from paraffin, soy wax, stearin, palm wax and beeswax candles. The study demonstrated that the combustion byproducts of all candle waxes tested are virtually identical in composition and quantity. And as emissions were all well under indoor air quality standards, the study confirmed the general lack of health or air-quality concerns with candles.

Don’t get me wrong. I love a good beeswax candle. They smell lovely even when unscented. But they are also VERY expensive compared to other types of candles. And they should be. As someone who has personally rendered bees wax I know how much work and time it takes for a small result. What looks like cups of wax comb caps often results in a few ounces of cleaned wax at best.

If you’re burning beewax candles as part of a spiritual practice that includes changing the energy in a room, well, more power to you. Just don’t tell me its “cleaning the air” without more evidence.

As a fun experiment regarding all of this, I purchased different kinds of wax from the grocery store, my own stash of beeswax, and from a supplier I also get soap fragrance oils from. I made four small 1.5 oz (43 g) wax votive candles, one each from paraffin “gulf wax” from the grocery store, joy wax (a mix of soy wax, other vegetable waxes, food grade paraffin, and proprietary ingredients), 100% soy wax and 100% bees wax. I used the same wax dipped wick in all of them, and then did some burn tests to look at soot. Wick was trimmed to the top of the container before burn, so that wicks started out at close the same length.

The results? Well, there really aren’t any. I burned each candle under a clean piece of glass for 30 minutes to collect soot, and then photographed the glass on a white background before cleaning it and moving onto the next candle. And like the European Candle Association study above, with the exception of the paraffin wax candle, I literally could not see ANY soot from a 30 minute burn from any of the candles (the paraffin candle left a very very fine light tan film that didn’t show up unless you looked at the surface in the light JUST right).

In an effort to double down on my soot collection, I lowered the level of the glass height and burned all 4 candles at once, thinking I’d do a side by side comparison. And then the glass got too hot and exploded. No damage to anything including me. Just lots of clean up. Thus ended that experiment.

Not to be outdone, I did a 2 hour burn of all 4 candles with a tinfoil shield leaning over the candles to catch soot. Again, a touch of soot from the paraffin, less from the joy wax (which also contains some paraffin) and nothing visible from the other two (I also discovered that its virtually impossible to photograph soot on tinfoil).

So, the long and the short of it is, unless you have specific health concerns, I wouldn’t personally worry too much about what candles you’re burning in your house. I tend to avoid paraffin because its derived from gasoline being refined (i.e. its a petroleum product), does have higher soot, and some studies have shown toxic VOC’s being released (albeit in very small amounts that are well below suggested risk limits). But I’ve been known to buy bags of mix and match candle bits at thrift stores, bring them home, melt them down in an old food can double boiler, strain through my dedicated wax strainer, scent if needed, and make new “mixed wax” candles more than once. It’s a fun way to reuse/reduce and make a lot of votives at once.

Soy wax is nice, but its also soft. You can’t really make a pillar candle out of soy easily, which is why you always see them in containers. So it has its limitations. And all soy, unless organic, comes from big agriculture and GMO soy beans, not a system I generally support, even if I’m not eating the result. (Side note: This is also why I don’t use soy oil in my soaps).

The limitations of beeswax have already been discussed. Primarily cost. It’s also tricky to get the wick size correct with its higher melting point. There is no one perfect candle answer.

I was often asked, when I was still selling at farmers markets, if I also sold candles. And my answer was always a resounding no. Candles are fun, but if you plan to make them to sell, there’s some testing and hoops you really should be going through for customer satisfaction and safety.

This includes testing every size candle/wax combination for correct wick size. For example, with a tapered candle, you’re looking for more complete combustion, so that the wax isn’t just running down the candle, making a mess and shortening burn time. With a pillar candle, you want a burn pool that extends almost out to the sides, but not quite. This keeps the melted wax from escaping and making a mess.

Wick too small? Your burn pool will be small and the candle will either not get enough oxygen and be drowned in your melted wax, or tunnel down through the candle giving off very little light.

Wick too big. Worst case scenario, it could be an actual fire hazard. Ever had a candle holder crack from the heat of the candle? I have. Which is why its always good practice to make sure you have warning labels on your candles (don’t leave burning unattended etc.) and that your liability insurance is aware that you’re making/selling candles. Some insurance companies won’t cover you for candles, as the risk can be high.

I’m also not a fan of putting other flammable substances in your candles. So leave the rose petals and pine needles off, even if they look really cool. Because if things go wrong, you’ve just added another fuel source.

If your candles are scented, you also need to test for “cold throw” and “hot throw”. I.e. does it smell strongly scented when cold AND when hot? Not all fragrances are good for both. Some aren’t good at either. Different types of wax also affect this dramatically. Buying supplies from a company that specializes in candle scents helps. They will have lots of information and reviews on each fragrance and how it behaves.

Knowing the right amount of fragrance to use is also tricky. Fragrance oils (or essential oils) are highly flammable. And some burn at lower or higher temperatures than others. So just adding more if a candle seems under scented is not the right answer. Generally, fragrance use is about 1.5 oz per pound of wax, or around 9% by weight. Add too much and it will literally “weep” out of your wax. Definitely not good. High quality safe ingredients IN the fragrance (ie no phthalates) also matters. That dollar store scented candle from who knows where may not be your best bet for indoor air quality.

Different waxes behave differently during melting/pouring. Paraffin especially will make shrink wells as it cools, causing the need for a second pour to create a level top. Your supplier should give you guidelines on optimum melt, fragrance addition and pour temperatures, which depend on the wax/fragrance combination.

Adding dye adds a whole additional layer of testing. Natures Garden, who specializes in candle wax and fragrance (along with soap making supplies) has this great manual on the ins and outs of candle making, if you want to take a deeper dive.

So, in short, don’t expect candles to clean your air (or at least show me a well designed study showing it does before making this claim – I sure can’t find one), never burn them unattended, and chose which types to burn based on where you draw the line regarding their ingredients and your health and also your experience with the quality of the brand. Mostly, I don’t worry about it too much.

© 2021 Miles Away Farm, where I originally started playing with making candles when I was a kid with my dad. (I once spilled red candle wax on a tile bathroom floor in a Holiday Inn hotel with my dad, and it took hours of scraping to clean it up!) I find we burn candles less and less as we get older, and don’t plan on offering candles for sale any time soon. That said, we’re miles away from being done with candles, and think it would be fun to play with tallow candles at some point! Want more content? Sign up for a monthly newsletter to your email inbox HERE.