The candles smell beautiful and create comfort: But some also release carcinogens

When the days are getting shorter and the chill outside, there’s nothing more pleasant than creating a cosy atmosphere at home. The lit candle in particular has become a symbol of autumn cosiness because it has something magical about it. The flickering of the flame calms us, adds warmth, fragrance and charm to the space. Especially on a cold evening, together with a cup of tea, it can bring us peace and comfort. But while the light of a candle soothes our minds, what we breathe as it burns may not be so innocent.

In fact, in recent years, it has been pointed out that popular scented candles – especially the cheaper paraffin ones – can release substances when burning that affect air quality in enclosed rooms and, with prolonged exposure, human health.

Various studies have shown that the smoke from some candles contains volatile organic compounds, some of which are considered carcinogenic. A romantic moment can subtly become a source of air pollution right in your living room.

Paraffin and fragrance: a double source of risk

Most commonly sold candles are made from paraffin, a petroleum derivative that releases substances such as toluene and benzene when burned. According to the World Health Organisation (WHO), benzene in particular is a proven carcinogen linked to leukaemia and lung cancer. Toluene, on the other hand, is an irritant to the eyes, nose and respiratory tract and, at higher levels, can cause headaches, dizziness and confusion.

The danger is particularly acute in rooms without adequate ventilation – typically in apartments where candles burn for long hours a day. The greatest risk is posed by cheap aromatic pieces which, in addition to paraffin, contain synthetic fragrances and dyes. It is the combination of these substances when burned that creates a mixture in which scientists have repeatedly measured not only carcinogenic benzene or formaldehyde, but also toxic gases such as sulphur dioxide and carbon monoxide.

In a Korean study looking at the impact of burning scented candles on indoor air quality, the concentration of fine dust particles increased up to 15 times the WHO recommended limits. In addition, it has been shown to alter the composition of airborne microorganisms – in poorly ventilated areas, higher levels and diversity of microbes were found after burning them.

Myths, facts and controversial studies

However, not all studies sound the alarm. For example, a 2014 study that measured the amount of volatiles released from burning candles concluded that concentrations were very low – below levels that could pose an immediate health risk. So with occasional candle use in well-ventilated rooms, there is no need to panic.

The problem, he said, only arises when there is an accumulation – that is, when several candles are burned in a small space on a daily basis for a long time . A single candle may not poison you, but a poorly ventilated apartment full of smoke can have a bad effect on the respiratory system.

However, some work suggests specific risks. Prolonged inhalation of fumes from synthetic fragrances and dyes can increase the risk of bladder cancer – because the volatile hydrocarbons that accumulate in the blood during burning are excreted in the urine. Benzidine dyes have been linked to this type of cancer for decades.

Not only wax, but also wick

It is not just the wax itself that posesa health risk. Until 2003, it was common to produce candles with lead wicks – and these released up to five times higher concentrations of lead when burning than is considered safe. Lead is toxic even in minute doses and affects the nervous system and hormonal balance. Today, lead wicks are banned in the European Union and the USA, yet they can be found in cheap products of unknown origin. A safer choice is candles with wicks made of cotton, wood or paper.

How to burn safely?

It is not the candle itself that poses a health risk, but the way we handle it. It is therefore advisable to follow simple guidelines: only light them in a well-ventilated room, never more than two at a time and do not leave them burning for more than two to three hours. The room should always be aired out after extinguishing, as the greatest amount of smoke is produced when the flame goes out. It is advisable to keep the wick short – around 5 millimetres – so that the wax burns evenly and less soot is produced.

When it comes to choice, doctors and environmentalists recommend preferring candles made from 100% beeswax or soy wax, or coconut or palm oil. These release fewer particles when burning than paraffin products and often contain natural essential oils instead of synthetic perfumes. There are also candles on the market that are free of dyes and chemical additives and are subject to stricter standards.

Candles made from natural waxes are not only healthier but also more environmentally friendly. When used properly, they are a safe and enjoyable way to create warmth and fragrance at home without unnecessary risks. Because even if a candle only burns for a short time, its effect, a feeling of peace and well-being, remains.