New research found that wax melts, considered safer for air quality than candles, actually release as many air pollutants as gas stoves and car engines

These Scented Products Pollute Indoor Air Even More Than Candles, Study Shows Here's what experts recommend to keep the air in your home pure

• A new study found that wax melts release more air pollutants than candles—comparable to gas stoves and diesel engines.
• Researchers previously found that other scented products, like cleaners and oil diffusers, also release air pollutants, which can cause respiratory issues.
• If you still want to use scented products, experts recommended ensuring your home has proper ventilation and air filtration.

Flame-free scented wax chunks called wax melts promise a non-toxic alternative to candles—but just how safe are these products, really?

That’s what Nusrat Jung, DSc, an assistant professor of civil engineering at Purdue University, wondered as she came across them on her walks down supermarket aisles.

Her curiosity sparked an investigation into the toxicity of some of these products, which typically melt and release a scent not via an open wick and flame but by a “wax warmer” with a contained heat source. The study results, recently published in the journal Environmental Science & Technology Letters, show that wax melts might not be as clean as some manufacturers claim.

In fact, the ones tested generated more indoor air pollution than candles, raising questions about how wax melts might affect health.

“What we found was surprising—significant formation of airborne nanoparticles that could impact indoor air quality in ways consumers might not expect,” Jung, a senior study author, told Health.

How Scented Wax Melts Affect Indoor Air

The research builds on the findings from two previous studies. For the first, researchers discovered that scented wax products, which have higher concentrations of fragrant oils than scented candles, release more volatile organic compounds (VOC) called terpenes. Exposure was higher in poorly ventilated areas. 

The other concluded that compounds released by scented products like cleaners and oil diffusers led to the formation of pollutants called nanoparticles.

For this study, Jung and her colleagues wanted to see whether scented wax melts—which are growing in popularity—also kickstarted the chemical formation of nanoparticles.

The researchers gathered unscented wax melts and 14 scented ones, including papaya, lemon, peppermint, and bamboo. Then they ran tests inside Purdue’s zEDGE (zero-Energy Design Guidance for Engineers) laboratory, which simulates a home-like indoor environment and is equipped with machines that scan and measure small particles. Paul Ziemann, PhD, a chemistry professor at the University of Colorado Boulder who wasn't involved in the study, told Health that the facility and instruments are “state-of-the-art.”

The researchers measured how often terpenes interacted with other indoor air pollutants like ozone, forming nanoparticles.

Scented wax melts produced three times more nanoparticles than candles, reaching similar levels of nanoparticles three nanometers or smaller as indoor stoves and diesel engines. Meanwhile, unscented wax melts did not produce terpenes or lead to nanoparticle formation.

Ziemann and Michael Waring, PhD, a professor of engineering at Drexel University who was not involved in the study, told Health that the study was well done. The research challenges the notion that wax melts are a safe alternative to combustion-based products like candles, Waring said.

“The findings indicate that nanoparticle formation from wax melts can be comparable to emissions from other strong sources, which is significant for indoor air quality and human exposure,” he added.

However, Waring also noted some study drawbacks, including that it only focused on one specific test environment. That means the findings might not apply in alternate conditions, like if there are variations in ventilation and air exchange rate. Additionally, the study measured only a sample of scented wax melts, so it’s unclear whether other products would show similar results.

How Indoor Pollution Could Affect Health

Scientists are still working to understand how repeated exposure to nanoparticles and VOCs affects our bodies. So far, research suggests it isn’t good.

“In the context of health, nanoparticles and VOCs are concerning because they can irritate the respiratory system,” Brandon Boor, PhD, an associate professor in civil engineering at Purdue and a senior author of the study, told Health. “Airborne nanoparticles have been linked to lung inflammation, cardiovascular effects, and other adverse health outcomes.”

A 2021 study reported that “terpene nanoparticles are associated with approximately five additional cardiorespiratory deaths per 100,000 people in the United States.”

However, Waring noted that the threat of nanoparticles depends on their composition, and no one knows for sure how problematic the ones formed by wax melts might be.

Should You Use Wax Melts?

While using wax melts is a personal choice, experts said there are certain factors to consider.

A big one is that there are still many open questions about how nanoparticles—particularly those associated with wax melts—influence the body. You’d have to know “how harmful these exposures are and how they compare to those from other sources, like cooking,” Waring said.

Other considerations include how ventilated your space is—indoor air quality monitors can help you determine this—and whether you tend to be sensitive to pollutants. “People with asthma, respiratory issues, or chemical sensitivities may want to limit their use, especially in poorly ventilated spaces where emissions can accumulate,” said Jung.

If you do use wax melts, an air purifier can help remove potentially harmful pollutants. They can be pricey, though; If you're up for it, a cheaper option is to build your own Corsi-Rosenthal box to reduce the levels of VOCs.

Remember that any scented products, not just wax melts, may contain volatile organic compounds that form nanoparticles.

“Unfortunately, due to a lack of stringent regulations, manufacturers are not always required to disclose all ingredients, making it difficult to determine which products are the safest,” said Jung. “A good rule of thumb is to choose products labeled as fragrance-free.”

Edited by Health with a background in health, science, and investigative reporting. Previously, she wrote full time about parenting issues for the app Parent Lab. Before that, she worked as a reporter for National Geographic covering wildlife crime and exploitation." tabindex="0" data-inline-tooltip="true"> Jani Hall Jani Hall Jani Hall is a news editor for Health with a background in health, science, and investigative reporting. Previously, she wrote full time about parenting issues for the app Parent Lab. Before that, she worked as a reporter for National Geographic covering wildlife crime and exploitation. learn more

This story originally appeared on: Health News - Author:Simon Spichak