Blog
Do Scented Candles Pollute the Air in Your Home?
Although scented candles are most often associated with a pleasant atmosphere, relaxation, and a sense of comfort, research is increasingly raising the question: do scented candles pollute the air in your home? Or do they simply freshen the air and give it a pleasant fragrance?
Scented Candles as Decoration and Gifts
Scented and decorative candles have long ceased to be merely a source of light. Today, they serve as interior design elements, gifts, collectible items, and part of a carefully curated home atmosphere.
People choose them for their color, shape, packaging, fragrance, and brand. They are popular gifts for many occasions. In recent years, scented candles have also found their place in private collections, decorative arrangements, and promotional gift programs offered by many brands.
Why Have Scented Candles Become a Subject of Research?
People use scented candles every day in millions of homes.
Their popularity has drawn the attention of researchers. Studies now examine whether scented candles pollute indoor air. They also assess how much these products may add to people’s overall exposure to indoor pollutants.
Indoor air quality deserves serious attention. We spend a large part of our lives indoors.
The problem starts when people equate fragrance with freshness. A pleasant atmosphere does not automatically mean good air quality.
Smell does not define air quality. The composition of the air we breathe does.
What Is Released from Scented Candles?
A candle can release fragrance compounds even when it is not burning. If you can smell it, substances are already entering the air.
These substances often include volatile organic compounds (VOCs).
Once the candle starts burning, emissions increase.
The flame heats the wax and speeds up the evaporation of fragrance ingredients. Melted wax releases additional aromatic compounds.
The wick and wax also undergo combustion. This process produces heat, light, water vapor, carbon dioxide, fine particles, soot, and various chemical compounds.
Why Is It Important What Candles Release into the Air?
Scientific literature indicates that exposure to certain airborne pollutants may be associated with respiratory problems, nervous system disorders, impacts on reproductive health, and an increased risk of certain diseases.
For some individuals, exposure to intense fragrances may cause headaches, dizziness, nausea, eye irritation, or a feeling of discomfort. Sensitivity to fragrances varies significantly among people, meaning that reactions can be highly individual.
Air pollution is most commonly associated with the respiratory system, but its effects are not limited to the lungs. Fine particles and certain chemical substances may have systemic effects on the human body.
SEE ALSO: Air Pollution and Health
What Did the REHVA Study Reveal About Whether Scented Candles Pollute Indoor Air?
The REHVA Journal, published by the Federation of European Heating, Ventilation and Air Conditioning Associations (REHVA), featured a study conducted by researchers from the Norwegian University of Science and Technology (NTNU).
The objective of the study was to investigate whether scented candles pollute the air in an apartment and to what extent kitchen exhaust ventilation can mitigate this effect.
The experiment involved 12 candles, while concentrations of PM2.5 particles, CO₂, temperature, and other air quality parameters were monitored.
The results showed a significant increase in PM2.5 particle concentrations and carbon dioxide levels during candle burning. In the scenario without the operation of kitchen exhaust ventilation, PM2.5 concentrations reached nearly 50 µg/m³. At the same time, the average CO₂ concentration was approximately 1,700 ppm, considerably above the commonly recommended value of 1,000 ppm and indicative of insufficient air exchange within the space.
SEE ALSO: CO₂ in Your Home – Is It There and Where Does It Actually Come From?
The Impact of Ventilation
The study did not examine apartments equipped with decentralized or centralized ventilation systems. Instead, it analyzed only the impact of kitchen exhaust ventilation.
However, the issue cannot be reduced solely to the individual compounds released during the burning of scented candles. In indoor environments, their contribution to air pollution adds to other pollution sources, including cooking, cleaning products, air fresheners, smoking, fireplaces, and various other sources of contamination.
Although kitchen ventilation systems are not designed with the purpose of improving air quality throughout an entire apartment, the research results showed that they nevertheless reduced concentrations of certain pollutants generated by candle combustion.
What Does the Research Published in Scientific Reports Show?
More recent research published in 2025 in the journal Scientific Reports further confirms that scented candles pollute indoor air. In this study, air samples were collected in residential spaces at three distances from a scented candle: directly next to it, 3 meters away, and 6 meters away from the source.
The results showed that particles do not behave in the same way. Larger PM10 particles had a shorter range and remained closer to the source, i.e., the candle flame. The smaller the particles, the more easily they spread throughout the space. PM2.5 and PM1 particles remained suspended in the air for longer periods and traveled farther from the source.
SEE ALSO: 11 Questions and Answers: How Do PM2.5 Particles Affect Health?
The study also indicated changes in the composition of the airborne microbiome following the use of scented candles. The authors note that additional research is needed but conclude that both the duration and location of candle use should be taken into consideration in order to reduce potential health risks.
What Do Studies Show About Emissions from Scented Candles?
The findings of the REHVA and Scientific Reports studies are not exceptions. Scientific literature indicates that the use of scented candles can generate volatile organic compounds (VOCs), as well as substances such as formaldehyde, benzene, and toluene.
In a study conducted by Derudi and colleagues, emissions of air pollutants from scented candles were analyzed under controlled conditions.
Maupetit and Squinazi investigated emissions of benzene and formaldehyde during the use of scented candles and fragrance sticks in indoor environments.
The amount of emitted substances depends on the type of wax, fragrance composition, wick quality, burning duration, and the level of ventilation within the space.
Are Scented Candles Similar to Air Fresheners?
Although they function in different ways, scented candles and air fresheners share one common characteristic – they introduce additional chemical substances into indoor spaces with the aim of creating a more pleasant smell.
For both categories of products, the same question arises: does a pleasant fragrance truly mean better air quality?
SEE ALSO: Air Fresheners: A Threat to Our Health
Can Residential, Local, and Room Air Purifiers Help?
If scented candles pollute the air, a logical question is whether household air purifiers can remove the resulting pollutants.
Residential air purifiers may help reduce the concentration of certain particles, but they do not eliminate the source of the problem. They do not prevent pollutants from being generated, they do not address increased CO₂ concentrations, and they cannot reliably remove all gaseous compounds that may be produced during the use of scented candles.
It is important to note that the studies mentioned in this article did not include apartments equipped with centralized ventilation systems and controlled fresh-air supply. Therefore, additional research is needed to better understand the impact of different ventilation systems on pollutant concentrations generated by candle burning.
From an air quality perspective, it is always more effective to prevent pollutants from being generated than to remove them afterward.
How Can the Risk Be Reduced?
Indoor air quality experts often emphasize three simple principles: ventilation, moderation, and education. This means ensuring adequate air exchange, reducing the frequency of use of products that emit pollutants, and understanding that a pleasant smell does not necessarily indicate healthier air.
In practice, this means:
- avoiding the use of candles, especially on a daily basis, in large numbers, and in poorly ventilated rooms;
- when candles are used, burning as few as possible and for the shortest possible period while ensuring adequate air exchange;
- avoiding candles that visibly smoke, produce soot, or emit particularly intense fragrances;
- choosing products with more clearly declared ingredients and without harmful or hazardous substances.
Conclusion
Scented candles can contribute to a pleasant atmosphere in the home and enhance the emotional experience of a space. At the same time, research shows that scented candles pollute indoor air.
When they are not lit, they release fragrance compounds. When they are lit, they generate not only fragrance but also combustion by-products, including fine particles, carbon dioxide, and other compounds.
This is important because we spend a significant portion of our lives indoors, and the air we breathe at home affects our daily comfort, concentration, sleep quality, and health.
Scented candles are a good example of why indoor air quality should not be assessed based solely on smell or a subjective sense of comfort. Air may seem fresh while still containing particles and chemical compounds that are invisible to us.
Indoor air quality should be viewed as a set of measurable characteristics rather than merely a subjective perception of comfort.
References
- Alam, A., Nacinovi, J., Oppi, K., Loste, T., & Cao, G. Field Investigation of Indoor Air Quality in One Norwegian Apartment Building with Burning Candles. REHVA Journal, Vol. 61, Issue 1, 2024.
- Yun, H., Seo, J. H., Kim, Y. G., & Yang, J. (2025). Impact of Scented Candle Use on Indoor Air Quality and Airborne Microbiome. Scientific Reports, 15, 10181. https://doi.org/10.1038/s41598-025-95010-0
- Derudi, M., Gelosa, S., Sliepcevich, A., Cattaneo, A., Rota, R., Cavallo, D., & Nano, G. (2012). Emissions of Air Pollutants from Scented Candles Burning in a Test Chamber. Atmospheric Environment, 55, 257–262.
- Maupetit, F., & Squinazi, F. (2009). Characterization of Benzene and Formaldehyde Emissions from Burning Incense and Scented Candles Indoors: Development of Exposure Scenarios and Recommendations for Use. Environmental Risk & Health, 8, 109–118.
