Do Candles Use Up Oxygen?

Scented to take away any nasty smells. Crackling wicks to create a relaxed atmosphere. Simple designs used for religious functions. Large. Small. Fat. Thin. Candles come in a plethora of designs and are used for a plethora of reasons.

But how exactly do candles work? We know that they need wax to melt and a wick to create the fire which will burn and most of us will be aware that fire needs oxygen. But what about the chemistry behind it all? Don’t worry, we won’t get too technical, but for those with enquiring minds, we delve into the basic science of what actually happens to create the relaxing ambiance so many of us enjoy and whether the oxygen around us is compromised.

Whist candles require oxygen to burn they use very little of what is in the air around them. Very few spaces are airtight with oxygen being circulated through windows, doors, etc. The oxygen circulates at a faster level than the candle will burn meaning your room will not be depleted of oxygen.

Can a Candle Burn without Oxygen?

As we can learn from other articles within our candle section at Flame Stuff, candles can be made from different elements including vegetable, animal, and petroleum sources. However, chemically all are predominantly hydrocarbons and will burn in the same way.

The wax and the wick work in tandem to ensure that the candle continually burns. When we light a candle we create a heat source that is hot enough to burn the wax. As the wax melts the hydrocarbons are broken down and drawn up into the flame, through the wick, and react with the oxygen in the air.

As the liquid wax is drawn up into the flame through the wick the heat from the flame vaporizes the liquid. This in turn produces light, heat, carbon dioxide, and water vapor. It is important that the wick is made from an absorbent material in order to draw up the liquid effectively.

So, how about the flame itself? How does that work? Whilst the meted candle wax is the fuel required to keep a candle burning an initial fire source is required. This can be in the shape of a match or a candle lighter. To produce that initial source you need a spark and again, oxygen.

Every burning process needs oxygen and burning candles is no exception so the answer to our question is no, a candle is unable to burn without a source of oxygen. An easy experiment to try at home is to place the lid on a jarred candle to make it airtight. Once all the oxygen in the jar is used up the flame will naturally extinguish.

Can Candles Affect your Breathing?

If you have asthma, or allergies then candles, especially scented ones can become a trigger. In these circumstances, it is recommended that you either use battery-operated tea lights or stick to nontoxic candles. The safest candles and ones least likely to trigger any allergies are made from coconut, soy, or beeswax. You want to be looking for wicks that are either wooden, unbleached cotton, or hemp. Pure essential oils will create scents that are most natural.

Whilst candles do emit toxins such as benzene and formaldehyde, known carcinogens, studies have shown that these are in such small quantities that they are much lower than recommended air quality limits set by WHO (The World Health Organization). Respiratory toxicologist Nikaeta Sadekar from the Research Institute for Fragrance Materials told the New York Times in 2021 that the chemical produced by scented candles “is so low that they pose no significant risk to human health”.

Is it OK to Burn a Candle in a Closed Room?

Very few rooms are completely airtight. Windows and doors will allow air to circulate at a rate that will replace clean air at a level that should negate any toxins which your candles emit.

However, should you encounter a closed room and a candle, our advice would be to not burn it without any form of ventilation. Without ventilation, a candle left burning long enough can produce enough carbon monoxide and other toxins to build up in the room. This in turn has the potential to cause significant health issues.

Of course, from a safety perspective, candles should never be left burning as they do pose a fire risk. Always risk assess, ensure that your candles are not close to a potential flammable source, are on a flat and non-flammable surface, and that your room has sufficient ventilation. Should you leave the room, be sure to safely extinguish the flame.

Does Burning a Candle Clean the Air?

Scented candles can certainly mask or eliminate any bad odors that you may have lingering in your room such as wet-dog or that fish you cooked for dinner but they don’t clean the air as such.

As we have already discussed, whilst the toxins that candles do release are not sufficient to cause any significant health problems the fact that they release toxins at all would negate any air cleaning qualities.

However, some waxes may go some way to improve the air quality around you, specifically beeswax. Both beeswax and soy candles inherently burn cleaner than their paraffin counterparts and some claim that when burning beeswax can produce negative ions. These ions then bind with positive ions which are in the air, including toxins that can help to eliminate them.

However, the study which we alluded to previously in our article which was carried out by the European Candle Association tested the emissions from various candle sources including both beeswax and paraffin. They concluded that the by-products from all materials tested were practically the same in both composition and quality.

Do you Need Ventilation when Making Candles?

There are many safety tips that you should follow when making candles and keeping the air circulation in the room in which you are working is one of them.

Of course, you should ensure that you protect yourself from any hot wax splashes or spillages by wearing the appropriate PPE (Personal Protective Equipment) and by always using the correct and recommended equipment.  Don’t leave the area in which you are working unattended, this is how accidents happen and things become damaged.

With regard to ventilation, it is advised that you keep a window or door open in order for the air to circulate. If you are in your kitchen and you have a cooker hood with a vent facility you can switch this on as an alternative to opening a window.


So, a minor chemistry lesson and we have hopefully, learned something new and answered your specific query. Candles need oxygen to work, without it you will not create your initial ignition source, and nor will your candle continue to burn.

Whilst a candle will take oxygen from the room in which it is burning unless that room is completely closed off and airtight it will not use up a level to render the air dangerous or pose any significant health risks. That said, if you do suffer from allergies or asthma some scented candles can be a trigger and nontoxic candles or replica alternatives are your best options.