With our doors and windows firmly shut against the winter cold, lighting a few scented candles is a trick many use freshen up a stuffy room. And with enticing aromas such as cotton fresh, mystic Orient, pine forest and spring meadow it is easy to see the allure.
But this act could be turning your home into a death trap as perfume chemicals can cause a dangerous cocktail that can kill, according to scientists. Experts say the simple perfumes can mutate on contact with air and if rooms are not properly ventilated they can build up to dangerous levels.
Tests were carried out on six similar modern houses over the course of five days by Professor Alastair Lewis of the National Centre for Atmospheric Science at the University of York.
Firstly he measured the levels of a range of ‘volatile organic chemicals’ (VOCs) and found a series of substances in the air, including benzene, which comes from outdoor vehicle pollution, and alpha-pinene, a pine perfume used in many cleaning products.
But the stand-out chemical was limonene, which is released by fragranced candles, plug-ins, air fresheners and cleaning products. Limonene is commonly used to give a citrus smell to scented candles and cleaning products and is considered so safe it is also used as a flavouring in foods.
However, once sprayed into our homes it doesn’t stay as limonene as it reacts with other gases which occur naturally in the air to create something else.
Back in the laboratory, Professor Lewis analysed its reactivity, and discovered that on exposure to ozone - which is present in the air all around us - every two molecules of limonene could produce one molecule of another chemical, formaldehyde.
Formaldehyde is used in embalming and heavy industry. It is a known cause of cancer in humans and in high levels can seriously affect health.
It is most closely linked with cancers of the nose and throat, and at the very least, it can cause sore throats, coughs, scratchy eyes and nosebleeds. Chemicals in air fresheners include include petroleum products and such as p-dichlorobenzene, which hardly evokes spring meadows or sultry spices.
But help is at hand for all those who can’t resist a scented candle or plug-in air freshener in the shape of the humble houseplant. For experts found there is a small group of pollution-busting houseplants which absorb particular chemicals, including formaldehyde.
As part of the research, each house in the study took in four specially chosen houseplants for six weeks, while Professor Lewis continued to record the levels of both limonene and formaldehyde.
Over those four weeks, the levels of limonene in the air did not go down but scientists found the levels of formaldehyde dropped markedly.
The experts say the research suggests that some houseplants – particularly English Ivy (Hedera helix), geraniums, lavender and many ferns – were good at absorbing formaldehyde.
In the UK we spend nearly £400 million a year on buying a total of 225 million aerosols, plug-ins, gels, candles and incense sticks, to scent our homes. The findings from the pioneering research project, which was aided by a team of experts from the BBC, were aired on Trust Me, I’m A Doctor, last Wednesday.
Last month doctor warned that E-cigarettes may be no safer than smoking tobacco because the process of vaporisation in the device can produce formaldehyde and other cancer-causing chemicals.
Experts said more research is urgently needed after scientific tests on the devices produced ‘alarming’ results’ suggesting cell damage by the process could lead to an ‘inevitable progression’ towards the disease, the journal Oral Oncology reported.
