The Truth About Candle Scents: Essential Oils vs. Fragrance Oils & Hidden VOCs

Candles are meant to bring warmth, relaxation, and a sense of peace into our homes. But what if the very candles we burn are filling our air with harmful toxins? The debate between natural essential oils and synthetic fragrance oils is ongoing, but science shows that choosing the right ingredients—100% pure, therapeutic-grade essential oils and properly diluted extracts—can make all the difference. We will not so much get into extract use as that is not debated at this point. Understanding what’s in your candles—from the wax to the wick to the scent—is essential for making a truly non-toxic choice.

Understanding VOCs: The Hidden Danger in Candles

Volatile Organic Compounds (VOCs) are chemicals that evaporate at room temperature and can have serious health effects when inhaled. Many candles, especially those made with paraffin wax, soy wax, synthetic fragrance oils, and chemically processed wicks, release harmful VOCs when burned.

According to a study published in the Environmental Science & Technology Journal, paraffin-based candles emit toluene and benzene, both of which are known carcinogens. The American Lung Association warns that toluene exposure can lead to dizziness, headaches, and respiratory issues, while benzene is linked to leukemia and other blood disorders.

Even soy wax, often marketed as a "cleaner" alternative, can be problematic. Most soy candles contain hydrogenated soybean oil, which is often genetically modified and processed with hexane, a petroleum-derived solvent. When burned, soy wax can still emit formaldehyde and acetaldehyde, both classified by the EPA as hazardous air pollutants.

Fragrance Oils: The Biggest Culprit

Most conventional candles are scented with synthetic fragrance oils, which are made from petroleum-based chemicals, including phthalates, aldehydes, and synthetic musks. These compounds contribute to indoor air pollution and have been linked to hormone disruption, allergies, migraines, and respiratory issues.

A 2016 study in the journal Air Quality, Atmosphere & Health found that scented candles and air fresheners release more than 100 different VOCs, many of which exceed safe exposure limits. When burned, these chemicals interact with ozone in the air, creating formaldehyde, a potent irritant and carcinogen.

What about Natural Fragrance? 

Many candle manufacturers promote natural fragrance oils as a safer alternative to synthetic ones. However, these oils are still lab-modified isolates extracted from plant sources, meaning they do not contain the full spectrum of plant compounds. They may still contain trace solvents or stabilizers that can release VOCs when burned.

Unlike essential oils, which provide therapeutic benefits, natural fragrance oils are chemically altered and lack medicinal properties. While they may not contain phthalates or petroleum byproducts, they are still not a truly "clean" option.

The Power of 100% Pure Essential Oils & Extracts

Unlike synthetic fragrances, pure, therapeutic-grade essential oils are derived directly from plants through steam distillation or cold pressing. This ensures no synthetic additives or harmful solvents. When used properly in candles—diluted correctly to avoid overheating and breakdown—essential oils provide a beautiful, natural aroma without toxic byproducts.

Scientific studies highlight the benefits of essential oils in aromatherapy:

• Lavender essential oil has been shown in clinical research to reduce anxiety and promote relaxation.
• Eucalyptus and tea tree oils have antimicrobial properties that can improve air quality.
• Citrus oils (like lemon and orange) contain natural limonene, which acts as an air purifier by neutralizing airborne toxins.

While essential oils can be sensitive to heat, proper blending techniques and dilution with stable natural extracts help preserve their integrity in candles. Choosing 100% pure, therapeutic-grade essential oils ensures you're getting the highest quality without chemical fillers.

Essential Oils: Science-Backed Safety When Properly Diluted

Unlike fragrance oils, essential oils are 100% plant-derived and contain bioactive compounds with proven health benefits. They are extracted through steam distillation or cold pressing, ensuring they remain free from synthetic additives.

Scientific Studies Supporting Safe Essential Oil Use

1. Dilution is Key – A study published in Aromatherapy Science: A Guide for Healthcare Professionals emphasizes that essential oils, when diluted properly, are safe for inhalation and topical use. High concentrations can be overwhelming, but diluting essential oils to 2% or less in wax ensures safe dispersion into the air. Our candles and melts are all diluted under 1% currently.
2. Air-Purifying Properties – Research from the Journal of Applied Microbiology found that essential oils like eucalyptus and tea tree oil have antimicrobial effects and can help purify indoor air when diffused or burned in candles.
3. Non-Toxic Aromatherapy Benefits – A study in Neuroscience Letters found that inhaling essential oils such as lavender and frankincense can reduce stress hormones and improve cognitive function without the risks associated with synthetic fragrance exposure.
4. No Elevated VOC Emissions – Research in Building and Environment compared essential oil-based candles to fragrance oil-based ones and found that candles scented with pure essential oils did not emit harmful levels of formaldehyde, benzene, or toluene, unlike those with synthetic or natural fragrance oils.
   

Are Essential Oils Safe for Pets & Children?

Concerns have been raised about the safety of essential oils around pets and children, and there are some, but the key issue is type, concentration, and exposure levels. While certain essential oils should be avoided under a certain age and for pets, unlike synthetic fragrance oil which is harmful to all under every circumstance, proper dilution and use of essential eliminates almost every risk.
*At SDG our candles scented with EO are diluted under 1% and we are always happy to share formulas for health-seeking info. We purposefully exclude known toxic EOs, though some EOs are still not recommended for pets and children under the age of 2. Most (if not all) studies on these oils involve improper dilution ratios and/or topical use of oil and do not give a well-rounded look at safe aromatherapy practices in essential oil use.

Studies Supporting Essential Oil Safety

• A 2020 study in Veterinary Medicine and Science found that when essential oils are diluted properly (below 3%) and used in well-ventilated spaces, they do not pose risks to pets.

Beyond Fragrance: The Importance of Clean Wax & Wicks

Even if you use the best essential oils, the type of wax and wick you burn matters just as much.

• Beeswax is the gold standard for clean-burning candles. It naturally purifies the air by releasing negative ions, which bind to toxins and remove them.
• Hemp wicks burn cleanly without the need for chemical processing, unlike many cotton wicks that are bleached or treated with synthetic stiffeners.
• Wooden wicks (when untreated) provide a sustainable, clean-burning option free from toxins.

Final Thoughts: Making the Healthiest Choice

When it comes to candles, ingredient transparency matters. Avoid paraffin, soy, synthetic fragrances, and chemically treated wicks. Instead, choose pure beeswax, hemp wicks, and 100% therapeutic-grade essential oils that are properly diluted (or extracts) for a clean, toxin-free burn.

Your home should be a place of wellness, not hidden pollutants. With the right choices, you can enjoy beautifully scented candles while protecting your health and the environment.

 

Scientific Articles & Books Referenced:

• https://www.sciencedirect.com/science/article/pii/S0160412021002154
  
• https://www.sciencedirect.com/science/article/abs/pii/S0962456206000580
• https://www.preprints.org/manuscript/202311.2008/download/final_file
• https://books.google.com/books?hl=en&lr=&id=tAljAwAAQBAJ&oi=fnd&pg=PT4&dq=Essential+oils+and+pet+safety+dilution&ots=SenGDYYpUv&sig=kK9dhjM1q6YtYrKGUJEiP_3Agac
• https://www.researchgate.net/profile/Debra-Rose-Wilson/publication/270823715_Historical_role_of_the_father/links/551be8d10cf2909047b977a7/Historical-role-of-the-father.pdf?_sg%5B0%5D=started_experiment_milestone&origin=journalDetail&_rtd=e30%3D#page=42
• https://pubs.acs.org/doi/epdf/10.1021/acs.est.3c07574?ref=article_openPDF