Study Reveals Scented Wax Melts Emit Harmful Nanoparticles, Comparable to Diesel Engines
Scented wax melts (SWMs), often marketed as a safer alternative to candles and incense, may pose unexpected health risks. A recent study published in Environmental Science & Technology Letters reveals that these popular home fragrance products release polluting nanoparticles (NPs) at levels similar to burning candles and even diesel engines.
Understanding Scented Wax Melts
SWMs are small, fragrance-infused wax pieces that release scents when heated, without an open flame. They are widely perceived as a cleaner, smoke-free, and non-toxic alternative to traditional scented candles. However, new research indicates that SWMs emit high levels of volatile organic compounds (VOCs), surpassing those from burning candles due to their concentrated fragrances and direct heating.
VOCs, including monoterpenes and their oxidized derivatives, react rapidly with indoor ozone—even at low concentrations—leading to the formation of harmful airborne nanoparticles. This process, known as new particle formation (NPF), results in tiny pollutant particles that can penetrate deep into the respiratory system.
Study Findings: A Hidden Air Quality Threat
The study, conducted in a controlled indoor setting, measured SWM emissions using advanced particle analysis technology. Researchers found that SWMs released significant amounts of terpenes, which reacted with indoor ozone to form peroxy and hydroperoxy radicals. Unlike traditional combustion sources, SWMs produced nanoparticles even in low nitrogen monoxide (NO) environments, intensifying particle nucleation.
Key findings include:
- High Particle Emissions: The NP production rate from SWMs was comparable to emissions from burning scented candles, gas stoves, diesel engines, and natural gas combustion.
- Terpene-Ozone Reactions: SWMs with high terpene content triggered rapid particle growth, with peak emissions aligning with terpene release.
- Ventilation Impact: Poor ventilation increased terpene concentration, further accelerating NP formation indoors.
Interestingly, an unscented wax melt did not trigger any significant nanoparticle emissions, reinforcing the link between fragrance compounds and indoor air pollution.
Health Implications: Respiratory and Organ Risks
Despite the absence of combustion, the study suggests that SWM-induced nanoparticles pose serious health risks. The inhalation of these particles may lead to:
- Respiratory Exposure: Nanoparticles can deposit directly into the upper respiratory tract at alarmingly high rates, increasing risks of lung-related health issues.
- Organ Impact: These ultra-fine particles can enter the bloodstream, potentially reaching organs like the brain and liver, raising long-term health concerns.
A Call for Awareness
With scented wax melts widely used in homes and workplaces, the findings underscore the need for greater awareness of indoor air quality risks. While SWMs may seem like a cleaner option, their emissions could contribute to unseen but potentially harmful air pollution, warranting further research and regulatory review.
