‘Tis the season. With snow falling outside, nothing feels better than being curled up inside enjoying a book or movie – maybe with a candle burning at your side. Candles, emblematic of colder weather, are a source of comfort for many. American retail sales of candles are estimated at $3.45 billion annually, and candles are featured in 7 out of 10 homes. Unsurprisingly, candle sales peak around Christmastime, their use adding to the festive ambiance of the holidays.
Thousands of years ago, when candles were first used as an essential light source, they were made from animal or plant oils. Now, paraffin wax (a petroleum by-product) is the most common material, accounting for more than 30% of the market. It’s inexpensive to produce, water-resistant, and easily molded, colored, and perfumed. But it’s also the most damaging to the environment and human health, equally in its production and throughout its use. As these candles burn, they emit soot, polycyclic aromatic hydrocarbons, phthalates, aldehydes, and nitrogen oxide gasses. These compounds are linked to reduced cognitive abilities and lung function in humans, especially children, and may also affect pets.
Other types of candles emit these compounds too, albeit to a lesser extent. Of these, animal or palm wax candles emit more particles than soy or beeswax candles. Besides lesser emissions, animal or plant-based waxes have a lesser environmental impact than petrochemical paraffin. Yet again, animal-based and palm waxes are associated with a greater ecological footprint than soy or beeswax, due to the resources required for the materials’ production.
Additives used in a candle, such as dyes and perfumes, influence emissions as well. The scent, in particular, is linked to the emission of aldehydes, such as formaldehyde. While studies have shown that scented candles emit more aldehydes than unscented options, exact emission profiles depend on the type of scent. Fresh and fruit fragrances emit more aldehydes than floral, oriental, or spice and edible aromas. As for soot and other hydrocarbons, oriental fragrance has the lowest emissions, while spice and edible scents always show the highest emissions. Synthetic scents have greater emissions than natural options.
Romantic setups of dozens of candles are linked to more than just an increased fire risk.
The market is shifting as awareness around potential health and environmental concerns grows. In recent years, soy and beeswax candles have exploded in popularity, as have all types of naturally-scented candles. More comprehensive studies documenting exact emissions profiles have been published, and researchers are working towards developing simple strategies so all candle producers can measure their products’ emissions.
Looking at candles more carefully has already led to significant positive changes in how they’re made. In the past, a candlewick could be 39-74% lead – a heavy metal that you certainly don’t want to be breathing in. Now, lead wicks are banned, replaced with paper, fabric, or wood instead. These provide all the beauty of candles that we know and love, and none of the toxic, teratogenic (disturbs the development of a fetus or embryo), or cancerogenic consequences associated with heavy metals.
For now, no matter what your favorite candle is made from, candles and good indoor air quality can be simultaneously enjoyed. Even synthetically-scented paraffin candles – those tied to the most emissions – will only reach unsafe thresholds after continued use in unventilated spaces. For all candles, to keep emissions to a minimum, trim the wick before use, keep to one candle at a time, and don’t burn for longer than a few hours. Under these conditions, burning candles likely won’t have any noticeable negative effects. Still, if you’re concerned about the environmental impact or suffer from chronic respiratory disorders, opt for soy or beeswax, and naturally-perfumed or unscented products. No matter your tastes, there’s a candle for you to indulge in this winter without having to worry about what you’re breathing in.