What Are VOCs? The Complete Guide to Understanding Volatile Organic Compounds in Your Sauna
If you’ve been researching saunas, you’ve probably come across the term “VOC” more than a few times. Companies throw it around. Marketing materials mention it. But what does it actually mean? And why should you care when choosing a sauna?
Let me explain this in plain English.
VOC: What It Actually Stands For
VOC stands for Volatile Organic Compounds. That’s a mouthful, so let’s break it down.
“Volatile” means these chemicals evaporate easily at normal temperatures. “Organic” in chemistry terms simply means they contain carbon atoms. “Compounds” are just combinations of different chemical elements.
The World Health Organization defines VOCs as any organic compound with a boiling point between 50-100°C and 240-260°C. In practical terms? These are chemicals that off-gas from materials and float into the air you breathe.
According to research published in Polymers (2020), VOCs include natural compounds like terpenes and alcohols, as well as ketones, aldehydes, ethers, aromatic hydrocarbons, and acids. These are the main pollutants found in indoor air.
Where Do VOCs Come From?
VOCs have two main sources: natural and man-made.
Natural sources include vegetation and wood. Trees release VOCs as part of their biology. Man-made sources include manufacturing processes, vehicle emissions, paints, adhesives, and building materials.
Here’s the important part for sauna buyers. Wood releases VOCs naturally. But the amount varies dramatically depending on the type of wood.
Why VOCs Matter More in a Sauna
A sauna is not a typical indoor environment.
When you heat any material, you accelerate the release of chemicals from that material. Your sauna reaches temperatures between 130-160°F or higher. At these temperatures, VOC off-gassing increases significantly.
Now consider this. You’re sitting in a small enclosed space. You’re breathing deeply. Your pores are open. And you’re trying to detoxify your body.
If your sauna wood is pumping out chemical compounds while you sit there sweating, you might be adding to your toxic load rather than reducing it. That defeats the whole purpose.
Softwood vs. Hardwood: A Massive Difference
Not all wood is created equal when it comes to VOC emissions. The research is clear on this point.
A comprehensive 2019 review published in Wood and Fiber Science stated that softwood emissions are approximately 50 times higher than hardwood emissions. That’s not a typo. Fifty times.
Softwoods like pine, spruce, and cedar contain high concentrations of terpenes. These are the oils that give pine forests their distinctive smell. While pleasant outdoors, these same compounds become problematic in enclosed heated spaces.
The dominant VOCs from pine include alpha-pinene and delta-3-carene. Research from Frontiers in Built Environment (2019) notes that pine also releases acrolein, described as “a known respiratory toxicant.”
Cedar presents similar issues. The terpenes cedrene and cedrol give cedar its insect-repelling properties. These same compounds act as lung irritants. Studies have documented that people with chemical sensitivities cannot tolerate these oils.
Hardwoods tell a different story.
The Science Behind Poplar’s Low VOC Profile
Poplar is a hardwood from the genus Populus. Unlike softwoods, it doesn’t contain significant resin or terpene content.
Research published in Atmospheric Pollution Research (2010) directly compared European aspen (Populus tremula) against Norway spruce and Scots pine using emission chamber testing following ISO 16000-9 standards. The findings were striking.
The study found that terpenes dominated softwood emissions at 70-90% of total VOCs. Hardwoods like poplar emitted primarily hexanal and pentanal with minimal organic acids. No significant terpene emissions.
A separate study by Hyttinen et al. measured poplar emissions before and after heat treatment at 190°C. Untreated poplar emitted 513 µg/m²/h of total VOCs. For context, this is dramatically lower than comparable softwood measurements.
The research published in Applied Sciences (2024) confirmed that poplar’s main VOC components before heat treatment were carbonyl compounds like hexanal, acetic acid, and pentanal, rather than the problematic terpenes found in cedar and pine.
What About Cedar and Pine?
Cedar remains the most marketed sauna wood in America. It’s moisture-resistant and looks nice. But those aren’t the only factors you should consider for something you’ll be breathing in daily.
The terpenes in cedar serve a biological purpose. They repel insects and resist rot. That’s useful for outdoor applications. In an enclosed heated space where you’re trying to support your body’s natural detoxification processes? Less ideal.
Pine and spruce share similar profiles. They’re inexpensive. Many sauna manufacturers use them for framing even when advertising a cedar exterior. So you might think you’re getting a “cedar sauna” while the hidden framing materials behind the walls release pine terpenes into your breathing space.
Understanding what your sauna is actually made of matters more than most marketing suggests.
VOCs and Chemical Sensitivity
Some people feel VOC effects immediately. Others don’t notice anything obvious.
The research on sick building syndrome gives us useful context. A 1984 World Health Organization report suggested up to 30% of new and remodeled buildings worldwide may cause excessive health complaints related to indoor air quality.
The symptoms associated with indoor VOC exposure include eye irritation, sore throat, headaches, fatigue, difficulty concentrating, and skin irritation. Research published in Indoor and Built Environment (2014) found correlations between VOC concentrations and these symptoms.
For people already dealing with chemical sensitivities, environmental illness, Lyme disease, or heavy metal toxicity, the stakes are higher. Their systems are already under stress. Adding more chemical exposure during a therapy meant to reduce toxic load makes no sense.
People fighting toxic overload need the cleanest possible sauna environment.
The Heat Factor
Here’s something many sauna companies don’t discuss openly.
Heat increases VOC release from materials. A study by McDonald and Wastney showed that thermal treatment at 140°C increased VOC emissions by about 60% compared to 120°C. Higher temperatures mean more off-gassing.
Your sauna runs hot by design. Whatever your sauna wood releases at room temperature will release faster and in greater quantities when you turn on the heaters.
This is why wood selection matters so much. A wood that’s already low in volatile compounds stays cleaner when heated. A wood already high in terpenes and oils releases even more at sauna temperatures.
Beyond the Wood: Hidden Materials
The wood you can see isn’t the only material that matters.
Many saunas use plywood or particle board somewhere in their construction. These manufactured wood products release formaldehyde and other aldehydes. Research consistently identifies formaldehyde as one of the most problematic indoor VOCs, classified as a carcinogen by the National Toxicology Program.
Adhesives, varnishes, and finishes add another layer of potential off-gassing. Even if the visible wood panels are good quality, toxic glues behind the walls can fill your sauna with unwanted chemicals.
Non-toxic materials throughout the entire construction make a real difference. Not just what you see on the surface.
Choosing Wisely
If you’re buying a sauna for health reasons, match your purchase to your priorities.
For someone with no chemical sensitivities who just wants to relax after workouts, cedar might work fine. Many people tolerate it without problems.
For someone dealing with environmental illness, recovering from mold exposure, fighting Lyme disease, or actively trying to reduce their body’s toxic burden? Poplar makes more sense. The science supports its lower VOC profile. Clinical experience backs this up.
The comparison between poplar and other sauna woods comes down to your specific situation and goals.
Questions to Ask Any Sauna Company
Before you buy any sauna, get specific answers:
What wood is used for the panels you can see? What about the framing you can’t see? Are any plywood or particle board components anywhere in the construction? What adhesives are used? Does the company use any finishes, varnishes, or treatments on the wood?
Vague answers should concern you. A company confident in their materials will give you straight answers.
The Bottom Line on VOCs
VOCs are real. They affect indoor air quality. Heat increases their release. And the type of wood in your sauna determines how much you’re exposed to during every session.
Softwoods like cedar and pine emit roughly 50 times more VOCs than hardwoods like poplar. These emissions contain terpenes and organic acids that can irritate airways and burden already stressed systems.
For anyone serious about using infrared sauna therapy for health purposes, the wood choice matters. It’s not marketing fluff. It’s basic chemistry and biology.
Choose accordingly.
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References:
- Adamová T, et al. “Volatile Organic Compounds (VOCs) from Wood and Wood-Based Panels: Methods for Evaluation, Potential Health Risks, and Mitigation.” Polymers. 2020;12(10):2289.
- Pohleven F, et al. “Volatile Organic Compounds Emitted from Untreated and Thermally Modified Wood – A Review.” Wood and Fiber Science. 2019;51(3):1-24.
- Hyttinen M, et al. “Comparison of VOC emissions between air-dried and heat-treated Norway spruce, Scots pine and European aspen wood.” Atmospheric Pollution Research. 2010;1(3):180-187.
- Skulberg KR, et al. “Health and Exposure to VOCs From Pinewood in Indoor Environments.” Frontiers in Built Environment. 2019;5:107.
- Nakaoka H, et al. “Correlating the symptoms of sick-building syndrome to indoor VOCs concentration levels and odour.” Indoor and Built Environment. 2014;23(6):729-737.
- Dallagnol LJ, et al. “Wood-Based Panels and Volatile Organic Compounds (VOCs): An Overview on Production, Emission Sources and Analysis.” Molecules. 2025;30(15):3195.
- Joshi SM. “The sick building syndrome.” Indian Journal of Occupational and Environmental Medicine. 2008;12(2):61-64.
- Environmental Protection Agency. “Sick Building Syndrome.” Indoor Air Facts No. 4 (Revised).
