Are Candles Bad for Indoor Air Quality?
Candles have been used for centuries to create atmosphere, fragrance and warmth in the home. Today they remain one of the most popular ways to make a space feel calm and inviting.
But with more conversations happening around indoor air quality, many people have started asking an important question.
Are Candles bad for indoor air quality?
The honest answer is that the situation is a little more nuanced.
Just like cooking, making a slice of toast or lighting a fireplace, when a candle is lit it undergoes a process called combustion where the wax vapour reacts with oxygen to produce heat, light and small amounts of gases and particles.
The key thing to understand is that not all candles behave the same way. The wax, fragrance ingredients, wick and overall formulation can make a noticeable difference to how cleanly a candle burns.
So while all candles produce tiny emissions because of combustion, higher quality candles that are carefully formulated can burn far more cleanly than cheaper mass-produced alternatives.
What actually happens when a candle burns
When you light a candle the heat from the flame melts the wax near the wick. The liquid wax is then drawn up the wick where it vaporizes and reacts with oxygen in the air. This reaction creates the flame and is known as combustion.
During combustion the candle produces heat and light, but it also releases very small particles into the air. Scientists often measure these particles as PM2.5 and PM10. These simply refer to particle size.
Particles of this size are also produced by many normal household activities including cooking, frying food and using fireplaces.
Some air quality experiments have shown that particle levels can rise temporarily when a candle is burning, & particularly at the moment the flame is extinguished.
However the amount produced can vary significantly depending on candle quality and formulation of the candle.
Why some candles produce more soot than others
The burning of any carbon-based fuel (including all wax types) produce carbon particles, however, a well-made soy candle created with the correct wick size, fragrance load, high quality fragrance oils and the correct fragrance load should burn cleaner and emit much smaller amounts of soot, while paraffin and cheaply made, mass produced candles tend to produce significantly higher levels.
Paraffin wax, which is derived from petroleum, has historically been the most common candle wax and can produce higher levels of soot when burned. By contrast, many modern candle makers use vegetable-based waxes such as soy, coconut or beeswax. Soy and other vegetable wax candles tend to:
• produce less soot
• burn more slowly
• emit fewer pollutants overall
Soy wax is also biodegradable and derived from renewable plant sources, which is one of the reasons many modern candle makers prefer it.
This doesn't mean every paraffin candle will produce soot, but wax choice and formulation can influence how cleanly a candle burns.
Fragrance ingredients and why they matter
Fragrance is another important factor that affects how a candle performs.
Many people assume candles made with essential oils are automatically better, but the science behind this is much more complex. Essential oils are natural plant extracts, but they are not always stable at the high temperatures involved in candle combustion.
Essential oils:
• can degrade when heated
• may change chemically when burned
in contrast, fragrance oils designed specifically for candles are created differently.
High quality fragrance oils formulated for candle use are designed to withstand combustion temperatures and are tested to perform safely when heated. They are also formulated to disperse fragrance evenly throughout the wax.
This is why many professional candle makers use carefully formulated fragrance oils rather than essential oils when creating scented candles.
Another factor to consider is that some mass produced candles may contain fragrance additives, stabilisers or ingredients that can release additional VOCs or irritants when burned. You can always message a small candle brand directly or check the website to see if it gives some indication into ingredient transparency and formulation quality. Most small business owners won't mind answering these queries.
Simple ways to reduce candle smoke
If you enjoy candles regularly there are a few easy things you can do to help keep them burning more cleanly.
Trim the wick before each burn
Keeping the wick trimmed to around 4mm helps maintain a steady flame and reduces the chance of excess soot forming.
Use a candle snuffer instead of blowing the candle out
Blowing out a candle can create a brief puff of smoke as the flame extinguishes. A candle snuffer gently cuts off the oxygen supply to the flame which puts the candle out more smoothly.
Burn candles in a ventilated space
Allowing some airflow such as opening a window slightly can help disperse any particles produced during burning. However, be sure not to place the candle directly in a draft as this disrupts the flame, causing it to flicker which interferes with the balance between the wax fuel and oxygen, leading to incomplete combustion which in turn, produces significantly more soot.
Avoid burning multiple candles in a small room
This helps prevent fragrance from becoming overwhelming and allows the candle to burn more comfortably.
Candle warmers as an alternative
If you love candle fragrance but prefer not to burn a flame, candle warmers can be a great alternative.
These devices gently warm the wax from below so the fragrance is released without combustion. Because there is no flame there is also no smoke or soot produced. So if you purchase a well made candle with clean, high quality ingredients such as soy wax and phthalate (etc.) free fragrance oils you are well on your way to cleaner indoor air.
Candle warmers can also be particularly useful in homes with pets or children, or for anyone who prefers not to have an open flame.
Choosing better quality candles
Many people love their candles and would never want to give them up completely.
The important thing to remember is that not all candles are created equal.
Higher quality candles that are carefully formulated using well selected ingredients often burn more cleanly than cheaper mass produced candles.
This is why many people choose candles made from plant based waxes and fragrances free from all the nasties, that have been specifically designed for candle use.
Here at The Scented Essence Candle Co. we go one step further when it comes to ingredient selection and formulation.
Our candles are hand poured using natural soy wax and carefully selected fragrance oils that are free from:
• phthalates • parabens • PEG • silicones • acrylates
• CMR substances • hormone disruptors
By carefully selecting our ingredients and testing thoroughly our goal is to create candles that are beautiful to use while being thoughtfully formulated with your wellbeing in mind.
For many people lighting a candle is a big part of their evenings, it signals slowing down and produces a sense of calm at the end of the day.
Used thoughtfully, candles can still be enjoyed while being mindful of indoor air quality. Choosing well made candles, trimming the wick and ensuring good ventilation can all help create a cleaner burning experience.
If you're looking for candles that balance beautiful fragrance with carefully selected ingredients you can explore our Luxury Candle Collection here or our smaller Amber Jar candles here.
You may also find our Ultimate Guide to Choosing Non Toxic Candles helpful.