Health experts are warning about the dangers of scented candles and incense this holiday season as evidence mounts that they can cause cancer.
In a recent article published in the Conversation, two renowned researchers from Ireland raised concerns about scented candles, which are popular throughout the year, emitting harmful substances such as carbon monoxide, chemicals, and various volatile organic compounds (VOCs).
The noxious gases and emitted chemicals can lead to coughing, sneezing, and irritation of the eyes, nose, throat, and lungs.
According to their research and other studies on this subject, the emissions from burning scented candles can elevate the risk of cardiovascular issues, lung cancer, and chronic bronchitis.
The people most at risk are in small homes and rooms with poor ventilation, such as a small apartment, a bedroom, or a bathroom.
Dr. Asit Kumar Mishra from the University College Cork and Dr. Marie Coggins from the University of Galway recommended vigilance in using scented candles in a recent editorial, stating, ‘The use of scented candles or smoking, especially in combination with obstructed wall vents and closed windows, exacerbates the exposure to indoor air pollutants for residents.’
‘While using scented candles, for example, peak fine particle concentrations could increase to 15 times the limits prescribed by the World Health Organization.’
They added: ‘Some of the organic compounds emitted by home fragrance products, such as benzene, phthalates and formaldehyde, may cause cancer – and burning scented candles and incense sticks indoors is a major source of formaldehyde.’
Burning holiday-scented candles and incense can release toxic gases like carbon monoxide, formaldehyde, and volatile organic compounds, which can irritate the respiratory system and increase the risk of heart disease, lung cancer, and chronic bronchitis
Candles are popular not only for their pleasing scents, but also for the aesthetic appeal they bring to interior decor. They’re used in more than 70 percent of households.
Burning scented candles indoors releases a mix of aromatic substances that linger in the air, including chemicals like aldehydes, hydrocarbons, and alcohols.
Some harmful compounds, like naphthalene, anthracene, and pyrene, are known to cause cancer.
In a 2014 study backed by the EPA, researchers tested a dozen scented candle samples to see what chemicals they released when burned.
They found 34 key compounds, including VOCs and other harmful chemicals, such as formaldehyde and acetic acid, both of which have been shown to cause potentially severe respiratory issues and skin irritation from short-term exposure, and cancer, asthma, cognitive impairment, and chronic respiratory issues when exposed over a long period of time.
Even short-term exposure to candle smoke has been shown to reduce cognitive function.
In one study, participants’ cognitive scores on a specific test averaged 48 before exposure, classified as ‘average’ cognition.
After exposure to pollutants from a burning scented candle, their scores dropped to an average of 40, classified as ‘below average’ cognition.
The researchers who authored the op-ed conducted their own study out this week in which they measured the air quality of 14 homes in Galway, Ireland, both 24 hours before and 24 hours after making changes to improve the house’s energy efficiency.
In one study, on average, about 60 percent of exposure to small airborne particles, which can be inhaled deeply into the lungs and enter the bloodstream, came from candle burning
About 20 million cases of cancer were diagnosed in 2022, but that number is projected to balloon to more than 35 million cases by 2050. Air pollution, such as that from scented candles, is a major driver of lung cancer
Researchers measured five pollutants, including CO2 and PM2.5 (tiny particles that can enter the lungs and bloodstream), along with temperature and humidity in two rooms of each house.
PM2.5 particles, invisible to the naked eye, come from car engines, burning wood, and smoking. Pollution-measuring devices were placed a meter above the floor near sources of pollution and ventilation, while occupants recorded their household activities, such as cooking, opening windows, and burning candles.
The results revealed activities like burning candles, smoking and blocking wall vents can be detrimental to indoor air quality with levels of PM2.5 and CO2 increasing.
The two doctors said: ‘In non-smoking homes, candle use can be the major source of particulate matter pollution.
‘Some of the organic compounds emitted by home fragrance products, such as benzene, phthalates and formaldehyde, may cause cancer – and burning scented candles and incense sticks indoors is a major source of formaldehyde.
A 2013 study in the journal Environmental Science & Technology found that burning candles was a significant source of fine particles in the air that can cause respiratory issues, increase the risk of heart attack and stroke, and impair brain function.
They measured the concentrations of particulate matter in the air and found that levels of particulate matter stayed elevated for hours after the candle’s flame was put out.
On average, candle burning was responsible for about 60 percent of total exposure to tiny airborne particles small enough to easily be inhaled deep into the lungs and even enter the bloodstream.
A 2020 survey found that around a quarter of candle users reported health issues potentially linked to candles, such as headaches, shortness of breath, and coughing
Using scented candles and incense in small rooms and bathrooms, especially where ventilation is poor, compounds the dangers as it exposes a person to higher concentrations of harmful chemicals.
A 2020 survey in Saudi Arabia revealed that 66 percent of people who answered researchers’ questions used scented candles, and 34 percent used them more than four times a month.
Around a quarter of people reported health issues that could be linked to their candle usage, including headaches (reported by 15 percent), shortness of breath (nine percent), and coughing (eight percent).
More prolonged exposure (over 60 minutes) was linked to more headaches, sneezing, and wheezing, though not significantly.
The researchers concluded: ‘This finding suggests that the emission of VOCs, phthalates and [particulate matter] by burning of scented candles like other fragrances products may be a reason for development of these adverse symptoms.’
Often the ingredients in a scented candle are a mystery because there is no federal requirement that companies list them anywhere.
Instead, the Consumer Product Safety Commission recommends – but does not force – manufacturers to disclose any potentially hazardous ingredients, such as lead in wicks or harmful fragrance chemicals.
As long as candles burn in well-ventilated spaces, the risks of harm will be minimal.
Jessica Wicks, an HVAC expert, told Real Simple: ‘Consumers should avoid lead or metal wicks and paraffin wax candles.
‘You should choose soy, beeswax, or coconut oil candles with cotton wicks. Higher quality candles are more expensive, but typically last longer.’
