Deep roots: realising the public health benefits of exposure to forest environments

Forests today constitute nearly one third of land cover worldwide, sequester nearly a third of carbon dioxide, and promote, maintain and restore health and wellbeing. Recent research has begun to unravel the therapeutic effects of forest environments. Reported benefits of forest therapy include mental health, cognitive function, the immune system, glycaemic control, pain relief, and hypertension. There is some evidence that biogenic volatile organic compounds emanating from trees themselves, so-called phytoncides, may also exert an antihypertensive effect. Decreases in objective measures of anxiety and depression have been attributed to forest environment exposure, with significantly lower scores on the profile and mood state questionnaire in the negative subscales of tension-anxiety, depression, anger-hostility, fatigue, and confusion. Limitations in the evidence base include small sample sizes, lack of research into long-term health effects, inconsistency around dose reproducibility and forest/woodland typology. The benefits to public health from investment in more detailed research could be a cost-effective strategy to mitigate the expensive burden of cardiovascular disease and mental illness on society, particularly in the wake of the ongoing COVID-19 pandemic. Isolating the elements of the forest-bathing experience responsible for its health benefits is difficult, although some evidence suggests that it may be a composite product of pleasant green scenery, soil, fresh air, sunlight, clean water, sounds of streams and waterfalls, bird song and the natural aromas of trees, plants, and flowers. The concept of green prescriptions is still in its infancy. With a greater awareness of the health benefits of forest immersion, the future medical consultation is likely to incorporate specific questions on this aspect of a patient's lifestyle. There may be a role for forest therapists who can counsel patients about the optimal intensity and duration of forest exposure for their individual health needs.

Developing an Application in the Forest for New Tourism Post COVID-19 -Experiments in Oku-Nikko National Park

Tourism, which has developed in line with the development of transport, has had to undergo major changes. As the push for SDGs spreads across the world, and for safe travel post-COVID-16, environmentally friendly smallgroup tourism is being promoted. It would be beneficial if the smartphones, which is used daily lives, could be useful in the nature for small groups of novice walkers to walk safety and knowing some new information about the area. However, the signal conditions are not always perfect in forests. Therefore, we have developed a smartphone application using Bluetooth Low Energy (BLE) beacons equipped with solar panels in Nikko National Park in Japan. Japan has long had the concept of forest bathing. Walking in the forest is told to have positive effects on the body and in the mind. We tried to clarify one of effects of forest bathing by measuring brain waves. We measured the effects of walking in nature by conducting simple EEG measurements while walking and measuring the degree of relaxation in the forest in 2021. © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.

Forest-bathing and physical activity as weapons against COVID-19: a review.

Strengthening the immune system in order to better withstand the threat of COVID-19 is an important way to ensure the protection of our health against the current pandemic associated with SARS-CoV-2. There are many ways to achieve this, but with current circumstances, certain modalities stand out as being the most valid and are certainly worth greater consideration. Here we review the effects that particular immuno-strengthening activities can have on limiting the severity of COVID-19 disease as well as preventing virus infection. Physical activity, in particular, should not be discounted as an important method of prevention of viral diseases as it triggers many biological processes within the human body which in turn lead to heightened natural defences against viral infections. When exercise is performed in forested areas, these protective health benefits may be increased since many plant species emit biogenic volatile compounds (VOCs) which, when inhaled, have many protective properties. These VOCs have been shown in particular to have immunostimulatory effects on the human body and, thus, they could be of use in the prevention and/or treatment of COVID-19. Being amongst trees may also help to alleviate stress and anxiety, lowering cortisol levels and consequently helping the proper functioning of the immune system. In the following work, we have performed an analysis of the available scientific literature which looks at the effects of physical exercise as well as 'forest-bathing' on the immune system's ability to fight disease, especially of course as it relates to COVID-19. Our review aims at shedding light on the benefits of exercising outdoors in green areas and suggests reforestation as a protective measure against future outbreaks.

Forest bathing and hiking benefits for mental health during the COVID-19 pandemic in Mediterranean regions.

Forest bathing (FB) has evidenced positive effects on individuals' mental health and well-being, but its benefits have mainly been studied in Asian biomes. The present study aimed to evaluate whether its benefits are also generalisable to other forests and biomes of the world, such as the Mediterranean. Eighty-six healthy adults of the general population were assessed before and after a FB near Barcelona (Spain) during the COVID-19 pandemic. A control-hiking group of participants was also analysed to contrast the FB effects on anxiety, affect, mood states and mindfulness. Results show that the guided practice of FB in Mediterranean-Catalan forests increases mindfulness states and positive affect and reduces anxiety and negative affect, with effect sizes being large to very large. Hiking also induced significant changes in all variables tested, but FB showed higher effect sizes. An exploratory analysis also revealed a different profile of the FB participants compared to the hiking practitioners, being highly educated women living in urban areas and with lower basal levels of psychological well-being. Accordingly, it is concluded that both Mediterranean FB and hiking (to a lesser degree) might be cost-effective strategies to promote and restore psychological well-being after the COVID-19 pandemic and to promote sustainable tourism in Mediterranean biomes of the European forested and protected areas.

The Feasibility and Impact of Practising Online Forest Bathing to Improve Anxiety, Rumination, Social Connection and Long-COVID Symptoms: A Pilot Study.

BACKGROUND: Long-COVID affects over 144 million people globally. In the absence of treatments, there is a need to establish the efficacy of therapies that improve patient outcomes. Forest bathing has been demonstrated to improve physical and mental outcomes but there is no evidence in Long-COVID patients. Accordingly, this pilot study sought to determine the feasibility and effectiveness of online forest bathing in adults with Long-COVID. METHODS: Feasibility was assessed by monitoring retention rates and participant feedback. In a waitlist controlled, repeated measures design, 22 Long-COVID patients completed weekly online surveys during a four-week waitlist control period, before engaging in four weekly online forest bathing sessions, completing post-intervention surveys following each session. RESULTS: In terms of retention, 27% did not provide post-intervention data, reasons for non-adherence were: feeling too ill, having medical appointments, or having career responsibilities. Compared with the waitlist control period, there were statistically significant improvements in Anxiety (49% decrease), Rumination (48% decrease), Social Connection (78% increase), and Long-COVID symptoms (22% decrease). Written qualitative comments indicated that participants experienced feelings of calm and joy, felt more connected socially and with nature, and experienced a break from the pain and rumination surrounding their illness. CONCLUSIONS: Online Forest bathing resulted in significant improvements in well-being and symptom severity and could be considered an accessible and inexpensive adjunct therapy for Long-COVID patients. Where people have limited access to in-person nature, virtual nature may offer an alternative to improve health and well-being outcomes.

Effects of forest environment (Shinrin-yoku/Forest bathing) on health promotion and disease prevention -the Establishment of "Forest Medicine".

Humans have enjoyed forest environments for ages because of the quiet atmosphere, beautiful scenery, mild climate, pleasant aromas, and fresh, clean air. In Japan, since 2004, serial studies have been conducted to investigate the effects of forest environments (Forest bathing/Shinrin-yoku) on human health. My research team has established a new medical science called Forest Medicine. The Forest Medicine is a new interdisciplinary science, belonging to the categories of alternative medicine, environmental medicine and preventive medicine, which studies the effects of forest environments (Forest bathing/Shinrin-yoku) on human health. It has been reported that Forest bathing/Shinrin-yoku has the following beneficial effects on human health:1 Shinrin-yoku increases human natural killer (NK) activity, the number of NK cells, and the intracellular levels of anti-cancer proteins, suggesting a preventive effect on cancers. 2 Shinrin-yoku reduces blood pressure and heart rate showing preventive effect on hypertension and heart diseases. 3 Shinrin-yoku reduces stress hormones, such as urinary adrenaline and noradrenaline and salivary/serum cortisol contributing to stress management. 4 Shinrin-yoku increases the activity of parasympathetic nerves and reduces the activity of sympathetic nerves to stabilize the balance of autonomic nervous system. 5 Shinrin-yoku improve sleep. 6 Shinrin-yoku increases the levels of serum adiponectin and dehydroepiandrosterone sulfate. 7 In the Profile of Mood States (POMS) test, Shinrin-yoku reduces the scores for anxiety, depression, anger, fatigue, and confusion, and increases the score for vigor, showing preventive effects on depression. 8 Shinrin-yoku may apply to rehabilitation medicine 9 Shinrin-yoku in city parks also has benefits on human health. 10 Shinrin-yoku may have preventive effect on COVID-19 by boosting immune function and by reducing mental stress.Taken together, these findings suggest that Shinrin-yoku may have potential preventive effects on non-communicable diseases.

Lower COVID-19 mortality in Italian forested areas suggests immunoprotection by Mediterranean plants.

The COVID-19 pandemic has induced dramatic effects on the population of the industrialized north of Italy, whereas it has not heavily affected inhabitants of the southern regions. This might be explained in part by human exposure to high levels of fine particulate matter (PM) in the air of northern Italy, thus exacerbating the mortality. Since trees mitigate air pollution by intercepting PM onto plant surfaces and bolster the human immune system by emitting bioactive volatile organic compounds (VOCs), we hypothesize a protective role of evergreen forested areas in southern Italy. We compared the mortality rate  due to COVID-19, the death number, the positivity rate and the forest coverage per capita in various Italian regions. Hectares of forest per capita and prevalence of deciduous versus evergreen forestal species were also estimated. In silico docking studies of potentially protective compounds found in Laurus nobilis L., a typical Mediterranean plant, were performed to search for potential antivirals. We found that the pandemic's severity was generally lower in southern regions, especially those with more than 0.3 hectares of forest per capita. The lowest mortality rates were found in southern Italy, mainly in regions like Molise (0.007%) and Basilicata (0.005%) where the forest per capita ratio is higher than 0.5 Ha/person. Our findings suggest that evergreen Mediterranean forests and shrubland plants could have protected the southern population by emission of immuno-modulating VOCs and provision of dietary sources of bioactive compounds. Moreover, in silico studies revealed a potential anti-COVID-19 activity in laurusides, which are unexplored glycosides from bay laurel. Overall, our results highlight the importance of nature conservation and applications to the search for natural antivirals.

Forest Bathing Is Better than Walking in Urban Park: Comparison of Cardiac and Vascular Function between Urban and Forest Parks.

Forest bathing is beneficial for human health. To investigate whether walking in forest or urban parks affects cardiovascular functions (CVFs), the present study was conducted in five forest trails in the Xitou Experimental Forest and in five urban parks in Taipei city. We recruited 25 adult volunteers for an observational pilot study in forest parks (n = 14) and urban parks (n = 11). CVFs were assessed by measuring the arterial pressure waveform using an oscillometric blood pressure (BP) device. The baseline and paired differences of systolic BP (SBP), central end SBP, heart rate, left ventricle (LV) dP/dt max and cardiac output in participants were lower before and after walking in a forest park than those in an urban park. In addition, the systemic vascular compliance and brachial artery compliance of those who walked in a forest park were significantly higher compared with those in an urban park. Linear mixed models demonstrated lower levels of SBP by 5.22 mmHg, heart rate by 2.46 beats/min, and cardiac output by 0.52 L/min, and LV dP/dt max by 146.91 mmHg/s among those who walked in forest compared to those in an urban park after controlling covariates. This study provides evidence of the potential beneficial effects of walking exercise in forest parks on CVFs.

Exploring the Physiological and Psychological Effects of Digital Shinrin-Yoku and Its Characteristics as a Restorative Environment.

This study investigated the physiological and psychological therapeutic effects of a digital Shinrin-yoku environment constructed indoors in an urban facility as well as the characteristics of the environment that contribute to restorativeness (restorative traits). We measured the fluctuations in the physical and mental states of 25 subjects by obtaining both before-after measurements and continuous measurements while exposed to a digital Shinrin-yoku environment that reproduced visual, auditory, and olfactory elements. The results demonstrated that the parasympathetic nerve activity was significantly increased and that the heart rate was significantly decreased during the exposure compared with that during the resting state. As for mood, five of the six Profile of Mood States (POMS) scales ("Tension-Anxiety," "Depression," "Anger-Hostility," "Fatigue," and "Confusion") were significantly decreased after the experience. In addition, psychological restorative effects were also confirmed, with a significant decrease in "negative affect" (measured using the Positive and Negative Affect Schedule (PANAS)) and a significant increase in the sense of restorativeness (Restorative Outcome Scale (ROS)) after the experience. In contrast, comparing the digital Shinrin-yoku environment with the actual forest environment and the urban environment using POMS, PANAS, ROS, and Perceived Restorativeness Scale (PRS), the psychological effects and environmental traits of the digital Shinrin-yoku were found to be considerably similar to those of the actual forest environment.

Evaluating In Silico the Potential Health and Environmental Benefits of Houseplant Volatile Organic Compounds for an Emerging 'Indoor Forest Bathing' Approach.

The practice of spending time in green areas to gain the health benefits provided by trees is well known, especially in Asia, as 'forest bathing', and the consequent protective and experimentally detectable effects on the human body have been linked to the biogenic volatile organic compounds released by plants. Houseplants are common in houses over the globe and are particularly appreciated for aesthetic reasons as well for their ability to purify air from some environmental volatile pollutants indoors. However, to the best of our knowledge, no attempt has been made to describe the health benefits achievable from houseplants thanks to the biogenic volatile organic compounds released, especially during the day, from some of them. Therefore, we performed the present study, based on both a literature analysis and in silico studies, to investigate whether the volatile compounds and aerosol constituents emitted by some of the most common houseplants (such as peace lily plant, Spathiphyllum wallisii, and iron plant, Aspidistra eliator) could be exploited in 'indoor forest bathing' approaches, as proposed here for the first time not only in private houses but also public spaces, such as offices, hospitals, and schools. By using molecular docking (MD) and other in silico methodologies for estimating vapor pressures and chemico-physical/pharmacokinetic properties prediction, we found that ß-costol is an organic compound, emitted in appreciable amounts by the houseplant Spathiphyllum wallisii, endowed with potential antiviral properties as emerged by our MD calculations in a SARS-CoV-2 Mpro (main protease) inhibition study, together with sesquirosefuran. Our studies suggest that the anti-COVID-19 potential of these houseplant-emitted compounds is comparable or even higher than known Mpro inhibitors, such as eugenol, and sustain the utility of houseplants as indoor biogenic volatile organic compound emitters for immunity boosting and health protection.

Complementary Medicine Strategies during the COVID-19 Pandemic - a Cross-Sectional study

Introduction: Complementary and Integrative Medicine (CIM) may provide an opportunity for health preventive or supportive self-treatment regarding COVID-19 infections. The study aims to explore self-help and prevention strategies and the emotional state during the pandemic in people who are familiar with CIM. Methods: We conducted an explorative cross-sectional study with an anonymous 41-item online-survey in German language among adults familiar to CIM (e.g. through a membership in a CIM association) from September 2020 to February 2021. A selection of 17 popular CIM methods was presented to capture self-help and prevention strategies used by the respondents and to assess the expected success of utilized methods. A visual analogue scale (0-10 points) was used to identify aspects of the emotional state. Statistical analysis was carried out descriptively. Results: We included 1,605 participants (mean age 55.4±12.6 (SD) years, 80.6% female). 32.5% of the respondents had a university degree and n=16 reported having had a COVID-19 infection. During the pandemic 86.8% of the participants reported a CIM use for health promotion. Staying and moving therapy in the nature for health promotion (e.g. forest bathing, hiking) (98.7%), healthy nutrition (98.6%) and physical activities (96.3%) were favored primarily. The part of people rating the health promoting effect as medium or strong ranged from 54.3% for Ayurveda to 97.6% for healthy nutrition. The analysis of the emotional state during pandemic revealed the lowest levels for “feeling lonely” (VAS mean 2.6±2.9) and “feeling anxious” (2.8±2.6) and the highest levels for “being attached to others” (6.2±2.5) and “well-being”(5.8±2.4). Conclusions: The health-conscious, predominantly female participants used a broad variety of CIM during the COVID-19 pandemic for health-care prevention and showed an overall stable emotional status. If and how their emotional state is related to this behavior should be addressed by further research. Keywords: Self-help strategies, health promotion, Covid-19;Complementary and Integrative Medicine cross-sectional study

Non-Pharmacological Measures in the Prevention and Treatment of COVID-19 Infection.

BACKGROUND: Previous pandemic and catastrophic events significantly changed the life of every human being, bringing him/her into a state of stress and the need to quickly adapt to new ways of daily activity. COVID-19 has a negative impact on all elements of health: social, physical and mental. Pharmacotherapy, as well as protective measures (isolation, wearing masks and maintaining physical distance) did not give the expected results. Vaccination has not yet led to herd immunity, so it is still jeopardizing every aspect of human health (1, 2). Non-pharmacological methods, such as stress and sleep control, physical activity and contact with nature are of great importance since they can significantly contribute to staying healthy during a pandemic. OBJECTIVES: The aim of this paper is to evaluate the impact of non-pharmacological measures such as stress and sleep control (with different measures against the negative effects of anxiety and depression on mental state) and the possible positive impact of "forest bathing" on improving the immune response to the virus and its consequences. METHODS: Available evidence-based studies on ways to com- bat stress and the effect of the proposed measures on human mental health and the im- mune system were analyzed. From the mentioned studies, recommended measures have been registered, which refer to stress and sleep control, diet and eating habits, contact with nature ("forest bathing", gardening), virtual communication and meditation (mindfulness practice). RESULTS AND DISCUSSION: The combined results of these studies indicate that COVID-19 has a chronic course and complications that significantly affect the physical, mental and emotional state of the patient. Proven positive effects of non-pharmacological measures can be applied in the daily practice of primary health care in the comprehensive fight against the COVID-19 pandemic. CONCLUSION: Non-pharmacological measures such as stress and sleep control, spending time in nature, healthy diet, and physical activity may improve the immune response to COVID-19. These measures, with their positive effects on all aspects of health, can make a major contribution to controlling and improving the quality of life during the COVID-19 pandemic.

Less COVID-19 deaths in southern and insular Italy explained by forest bathing, Mediterranean environment, and antiviral plant volatile organic compounds.

The coronavirus disease 2019 (COVID-19) is causing major sanitary and socioeconomic issues, yet some locations are less impacted than others. While densely populated areas are likely to favor viral transmission, we hypothesize that other environmental factors could explain lower cases in some areas. We studied COVID-19 impact and population statistics in highly forested Mediterranean Italian regions versus some northern regions where the amount of trees per capita is much lower. We also evaluated the affinity of Mediterranean plant-emitted volatile organic compounds (VOCs) isoprene, α-pinene, linalool and limonene for COVID-19 protein targets by molecular docking modeling. Results show that while mean death number increased about 4 times from 2020 to 2021, the percentage of deaths per population (0.06-0.10%) was lower in the greener Mediterranean regions such as Sardinia, Calabria and Basilica versus northern regions with low forest coverage, such as Lombardy (0.33%) and Emilia Romagna (0.29%). Data also show that the pandemic severity cannot be explained solely by population density. Modeling reveals that plant organic compounds could bind and interfere with the complex formed by the receptor binding domain of the coronavirus spike protein with the human cell receptor. Overall, our findings are likely explained by sea proximity and mild climate, Mediterranean diet and the abundance of non-deciduous Mediterranean plants which emit immunomodulatory and antiviral compounds. Potential implications include 'forest bathing' as a therapeutic practice, designing nasal sprays containing plant volatile organic compounds, and preserving and increasing forest coverage. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s10311-021-01309-5.

Mindfulness and Shinrin-Yoku: Potential for Physiological and Psychological Interventions during Uncertain Times.

Mindfulness and Shinrin-yoku (SY) translated as forest bathing, is potentially effective to alleviate mental health issues related to the COVID-19 pandemic and beyond. The purpose of this article is to provide a translational and pragmatic approach to understanding mindfulness in the context of SY and psychological wellbeing through a rapid review of the literature. The background of mindfulness and SY practice are discussed and the emotional, neuroendocrine, and neurobiological responses are examined. Next, a rapid review of the literature examined six studies, published between 2010 and 2020 to determine what is known regarding the relationship between SY, mindfulness, and psychological wellbeing. The studies included 21-360 participants with a mean age of 20-55 years. The results demonstrated a significant positive correlation between nature, mindfulness, and measures of psychological wellbeing. During uncertain events, including COVID-19, weaving mindfulness with SY may be specifically important to at-risk groups, those experiencing depression, loneliness, and social isolation, and at-risk populations such as college students, veterans, and professionals with high levels of stress. The goal of this review is to provide a thorough background and support of this cost-effective modality to promote overall psychological wellbeing as a preventative measure to those at risk or experiencing psychological illnesses.