Forest Volatile Organic Compounds and Their Effects on Human Health: A State-of-the-Art Review

Abstract

The aim of this research work is to analyze the chemistry and diversity of forest VOCs (volatile organic compounds) and to outline their evidence-based effects on health. This research work was designed as a narrative overview of the scientific literature. Inhaling forest VOCs like limonene and pinene can result in useful antioxidant and anti-inflammatory effects on the airways, and the pharmacological activity of some terpenes absorbed through inhalation may be also beneficial to promote brain functions by decreasing mental fatigue, inducing relaxation, and improving cognitive performance and mood. The tree composition can markedly influence the concentration of specific VOCs in the forest air, which also exhibits cyclic diurnal variations. Moreover, beneficial psychological and physiological effects of visiting a forest cannot be solely attributed to VOC inhalation but are due to a global and integrated stimulation of the five senses, induced by all specific characteristics of the natural environment, with the visual component probably playing a fundamental role in the overall effect. Globally, these findings can have useful implications for individual wellbeing, public health, and landscape design. Further clinical and environmental studies are advised, since the majority of the existing evidence is derived from laboratory findings.

The Psychological and Physical Effects of Forests on Human Health: A Systematic Review of Systematic Reviews and Meta-Analyses

“…Other possible benefits mentioned include promoting brain function by reducing mental fatigue, inducing relaxation, and improving cognitive performance and mood. The authors emphasised that tree composition can significantly influence the concentration of certain VOCs in forest air [ 50 ]. The scientific literature on forest-based interventions too rarely describes the structure of the forests in which the interventions were carried out.…”

To stress or not to stress: Brain-behavior-immune interaction may weaken or promote the immune response to SARS-CoV-2

“…A pilot study observed an increase in NK-cell activity ( Tsao et al, 2018 ). Part of the effect can be attributed to volatile organic compounds that are inhaled ( Antonelli et al, 2020 ). Even though placebo effects cannot be ruled out, forest bathing is still recommended for many reasons.…”

Prediction of Natural Volatile Organic Compounds Emitted by Bamboo Groves in Urban Forests

“…The above five substances have also been shown to be the main components of NVOC in several prior studies. In particular, α-pinene, 3-carene and camphene accounted for 70% of the total emissions, with α-pinene known to have anxiolytic, anti-inflammatory, antioxidant, and antiproliferative effects, and 3-carene is known to improve inflammatory conditions [13,[26][27][28][29]. Finally, camphene was found to have an antiproliferative, antioxidant, antinociceptive, and antihyperlipidemic effects, and also can enhance metabolism activities [30][31][32].…”

“…As previously mentioned Stephen and Rachel Kaplan argues, various studies have already demonstrated that forests can promote diverse physiological and psychological health conditions. These forest healing effects includes olfactory, visual and socioenvironmental effects, among which the typical is the olfactory effects through phytoncide emitted by trees [9][10][11][12][13]. "Phytoncide," a complex chemical secreted by trees to protect themselves from external harmful factors, is a representative healing factor in nature.…”