Smell the forest and be well

One of the most important pathways through which the beneficial effects of nature are transmitted to us is the air we breathe. We breathe about 10 000 L of air per day, so its quality matters.

There is a lot of invisible goodness floating in the forest air: microbes, ions and volatile organic compounds, monoterpenes. There are more than 1000 different kinds of them. Monoterpenes determine the smell and taste of each plant, the essential oil. Common monoterpenes include d-limonene, alpha- and beta-pinene, beta-myrene, and eucalyptol, menthol and geraniol.

Trees produce the most monoterpenes, some species more than others. The density of tree and leaf cover, climate, season, time of day and wind conditions affect the concentration in the air. Monoterpenes are most abundant in leaves and needles, and in resin. Among other things, they repel herbivores and diseases, attract pollinators and birds, and carry messages between plants.

Monoterpenes have been used by humans for thousands of years as essential oils: as medicines, perfumes, insecticides or stimulants.

Monoterpenes are easily absorbed through mucous membranes and skin. Through the sense of smell, they quickly act on the central nervous system to stimulate or calm the body. Others include antiseptic, muscle relaxant, analgesic and anti-inflammatory effects (Antonelli et al., 2020). Some also activate the immune system and T-cell function and act as anticancer agents (Li et al., 2006).

In Finland, the best sources of monoterpenes are the common pine, spruce, birch and juniper. Conifers have a low evaporation rate all year round, deciduous trees only during the growing season. They are most abundant under trees on sunny, calm summer days, especially in the early morning or late afternoon.

Monoterpenes are often confused with phytoncides, a broader group (about 5000) of plant defence compounds. Not all phytoncides are monoterpenes, but monoterpenes are phytoncides.

HOW TO USE ESSENTIAL OILS

- add essential oil to the air in your home using a diffuser or evaporator pad
- use on skin e.g. diluted in jojoba oil (NOT raw, too strong!)
- add a few drops to bath water