Slow-grown, naturally more durable
In northern Finland, pine grows slowly. Short summers and cold winters force the tree to build up its annual growth rings layer by layer, slowly and carefully. The slower the growth, the denser the wood. Northern pine heartwood is rich in resin, hard and dense. It withstands mechanical stress better than its faster-growing relatives from further south.
As a building material, this translates into longevity. But it also means something else: the resin and natural oils that northern pine accumulates over decades are more valuable to indoor air quality than many people realise.
Pine breathes with you
Wood is a hygroscopic material. When the air is humid, it absorbs moisture. When the air dries, it releases that moisture back into the room. This moisture-buffering capacity is particularly strong in solid log structures, where large amounts of wood are in direct contact with indoor air. According to research, the more exposed wood there is on interior surfaces, the better humidity levels remain within the optimal range for health: 30–55%.
Stable humidity is about more than comfort. It affects respiratory function, perceived temperature and sleep quality. All without mechanical regulation.
Pine helps keep surfaces clean
Pine has particularly strong antibacterial properties compared with most other wood species. Its natural oils inhibit the growth of bacteria and mould, both on surfaces and in the air. The same mechanism also slows the reproduction of house dust mites, which is particularly relevant for families affected by asthma or allergies.
Northern pine heartwood contains especially high concentrations of resin. This is not merely an aesthetic feature. It makes the wood naturally more durable and more effective against bacteria than its southern counterparts.
Alpha-pinene: the scent of pine is more than just a fragrance
The fresh air of a pine forest has a calming effect. Almost everyone is familiar with this experience. But it is not simply imagination or nostalgia; there is a chemical explanation behind it. This is also why sanatoriums were once built in pine forests.
Pine wood releases significant amounts of alpha-pinene (α-pinene), by far the most abundant volatile organic compound in Nordic pine, accounting for as much as 40–47% of all volatile compounds. Recent research at the University of Oulu confirms that alpha-pinene is also the most economically valuable compound in pine wood, with a value even higher than that of spruce.
However, its economic value is not the most interesting aspect. Alpha-pinene and beta-pinene have been shown to increase immune system activity. These cells identify altered cells and respond to them. Stress hormones are known to reduce the activity of these immune cells. After spending time in a forest, students showed reduced stress hormone levels and increased immune cell activity, with results corresponding to the effects of pinene measured in laboratory conditions. In a mouse study, inhalation of alpha-pinene slowed tumour growth.
In a log building, these compounds are continuously released at low, safe concentrations. Not in a sudden burst, but as a steady flow. Just like in a northern pine forest.
Wood literally lowers blood pressure
Touching a wooden surface lowers blood pressure and skin conductance compared with touching aluminium or plastic. This is not a metaphorical effect, but a genuine physiological response that can be measured. In a school study, stress levels subsided more quickly in a classroom with wooden interiors than in rooms built with concrete or board materials, as confirmed by heart rate variability measurements. In a care home, introducing more wood materials increased residents' social interaction and improved their awareness of their surroundings. A bed made of pine improved sleep quality and autonomic recovery, as measured by EEG and ECG.
Wood therefore influences people in many different ways. This is not a marketing claim, but a scientifically measured fact.
In tourism, guests buy an experience and get the health benefits as an added bonus
Tourism entrepreneurs do not compete on location or amenities alone. They also compete on the feeling guests experience when they wake up after their first night. What they tell their friends afterwards. This is a feeling we Finns know well: we always seem to sleep better at the cottage.
A building made from logs of slow-grown northern pine does several things simultaneously: it automatically balances indoor humidity, continuously releases alpha-pinene and other terpene compounds, inhibits mould and bacterial growth on surfaces, and creates an acoustically pleasant environment with minimal reverberation. All without additional equipment or maintenance.
It is an advantage built into the material itself. Guests may not necessarily be able to put it into words, but they feel it throughout their bodies, making them more likely to return.
Kontio SmartLog and northern pine
Kontio builds with slow-grown northern pine. The non-settling structure of Kontio SmartLog logs allows the wood to do what it does best, decade after decade: breathe, balance humidity and release natural oils into the air. Not just during the first few years, but throughout the entire lifespan of the building.
Sources
Künzel et al. (2004). Moisture buffering effects of interior linings made from wood or wood based products. Fraunhofer Institute for Building Physics.
Laireiter et al. (2013). Active Anti-microbial effects of Larch and Pine Wood on Four Bacterial strains. BioResources 9:273–281.
Hiramatsu et al. (2008). House dust mites and their sensitivity to wood oils and volatiles. Journal of Wood Science.
Manninen et al. (2002). Comparing the VOC emissions between air-dried and heat-treated Scots pine wood. Atmospheric Environment 36:1763–1768.
Österberg, P. et al. (2026). University of Oulu research project on the economic value of VOC compounds from sawmills. Reported in Kaleva on 17 October 2026.
Li et al. (2006). Phytoncides (Wood Essential Oils) Induce Human Natural Killer Cell Activity. Immunopharmacology and Immunotoxicology 28:319–333.
Li et al. (2008). A Forest bathing trip increases human natural killer activity and expression of anti-cancer proteins. Journal of Biological Regulators and Homeostatic Agents 22:45–55.
Kusuhara et al. (2012). Fragrant environment with alpha-pinene decreases tumor growth in mice. Biomedical Research 33:57–61.
Sakuragawa et al. (2008). Effects of contact with wood on blood pressure and subjective evaluation. Journal of Wood Science 54:107–113.
Grote et al. (2009). Gesundheitliche Auswirkungen einer Massivholzausstattung in der Hauptschule Haus im Ennstal. Human Research Institute, Weiz, Austria.
Anme et al. (2012). Behavior Changes in Older Persons Caused by Using Wood Products in Assisted Living. Public Health Research 2:106–109.
Grote et al. (2003). Evaluation der Auswirkungen eines Zirbenholzumfeldes auf Kreislauf, Schlaf, Befinden und vegetative Regulation. Joanneum Research, Weiz.
Muilu-Mäkelä, R., Haavisto, M., Uusitalo, J. (2014). Health effects of wood materials in indoor environments – a literature review. Metla Working Papers 320.