Combating stress: green care in human health and wellness

HUMAN-ENVIRONMENT INTERACTION

Fairfield Osborn (1948) in his book ‘Our Plundered Planet’ could have been the first to warn about environmental degradation. This came 14 years before Rachel Carson’s well-known ‘Silent Spring.’ Osborn’s path breaking work focused on sustainability without actually using the word. As he concluded with “must temper [our] demands... and conserve the natural living resources of this earth in a manner that alone can provide for the continuation of ... civilization” (p. 201), he could already foresee the events of the decades to follow – the massive destruction to the planet even in the late forties.

Three distinct types of human-arboreal relationships have been suggested – nostalgic, nurturing and empowering . It may then be recommended that iophilia or connectedness with nature may be an approach to human well-being and wellness besides inculcating pro-environmental values and behaviour (Vainio, 2025). Environmental psychologists drawing from Conservation Psychology distinctly focus on natural environment and its direct or profound impact on human orientation and outcomes. Thus it depends heavily on conservation of biodiversity and sustainability of the environment (Sen 2010a, 2017, 2019).

STRESS REDUCTION THEORY

Exposure to nature can be both physically and psychologically healing and is an effective means of combating stress in our daily lives. The Stress Recovery or Reduction Theory (SRT) proposed by Roger Ulrich in 1991 can be applied in both micro and macro environments-i.e. at home or office and also to towns and cities. In eco-psychology Stress Reduction Theory is a major hypothesis explaining the relationship between mental stress and anxiety with exposure to the environment (Ulrich et al., 1991). SRT states that mental stress can be significantly reduced by exposure to natural settings while on the contrary mental stress is induced or enhanced by artificial settings. Adding trees, indoor plants, green spaces can significantly contribute to city or town planning and is necessary for urban planning (Sen, 2024a).

Attention Restoration theory emphasizes the fact that exposure to nature can actually remove fatigue and restore attention thus enabling better focus on work, suggesting that ‘softly fascinating’ qualities of the natural environment facilitate effortless attention.

Ulrich et al. in 1991 conducted an experiment in which 120 participants were made to view a stressful film followed by audio and video recordings of different natural and urban settings. Physiological results revealed that stress recovery was faster when the participants were exposed to natural as compared to urban environments. The results indicated the possibility of the significant involvement of parasympathetic nervous system in the responses to natural environment but no such involvement could be detected for urban settings. On measuring brain activity in healthy adults without stress Ulrich reported higher production of serotonin when those subjects were exposed to natural landscapes.

PHYTONCIDES

Plants release chemicals called phytoncides which are allelochemicals stimulating the production of moodboosting or happy hormones in humans – serotonin and endorphins. Plants release these volatile organic compounds phytoncides which are inhaled by humans causing a sense of ‘happiness’ and ‘well-being.’ Thus besides emitting oxygen as by-product plants actually trigger a sense of ‘happiness’ in humans. Merely by gazing at plants and greens, there is reduction in stress hormone cortisol levels. Thus being in the presence of nature can be mentally stimulating and advantageous both for human health and memory.

Phytoncides manage or destroy numerous microorganisms and viruses in air, cleanse the air and improve our self-cleansing ability. When people inhale phytoncides, their bodies respond by boosting the action and increasing the number of natural killer (NK) cells, a type of white blood cell. These terpenoid-based volatile organic compounds (VOCs) are produced by all plants in different levels and play a major role in immune response against pathogens and predators (Singh and Sharma, 2015). Phytoncides may be either inducible or constitutive (Sharifi-Rad et al ., 2017). The inducible are active following exposure to biotic or abiotic stressors and protect from herbivores and microbe pathogens while constitutive phytoncides possess antifungal and antimicrobial defence.

According to Angelucci et al . 2014 phytoncides stimulate the autonomic nervous system and reduce stress by activating the olfactory bulb thereby enabling the parasympathetic nervous system (PNS) to be more dominant than the sympathetic nervous system (SNS). Phytoncides led to 17% reduction in SNS activity while promoting an equal rise in PNS activity (Heo et al ., 2023) Following the rise in PNS activity numerous stress hormones viz. adrenaline, noradrenaline and cortisol play significant roles in stress reduction. Reductions in cortisol have also been correlated with increased natural killer (NK) cell activity (Park et al., 2007). Li et al. (2009) reported that forest environment increased human NK cell activity and number, and intracellular anti-cancer proteins in lymphocytes, and that the increased NK activity lasted for more than 7 days after trips to forests both in male (Li, 2010) and female subjects (Li, 2008).

Studies indicate that plants can improve attentiveness, focus and productivity, making them advantageous for both work and leisure activities. Some examples of such plants are lavender- known for its calming scent and ability to reduce anxiety, snake plant- popular choice for air purification and low- maintenance care, peace lily-known for its air-purifying qualities and ability to promote relaxation, ZZ Plant (Zamioculcas zamiifolia)- a very low-maintenance plant that can survive in low-light conditions, jasmine- offers a soothing fragrance that can help reduce stress and anxiety, gerbera daisy- adding colour and uplifting mood

FORESTS AND FOREST BATHING

Forest bathing, a traditional Japanese practice, offers psychological and physiological benefits through phytoncide exposure. Forest bathing, also known as shinrin-yoku in Japanese, is a traditional practice of spending time in nature to relax and improve health and wellness in humans through stress management. It is a therapeutic practice of being in a forest and connecting with nature through the five senses. There are several reports stating the therapeutic use of phytoncides through forest bathing which is effective in improving human immune system by increasing NK cells, perforin and granulysin (Tsao et al., 2018). Citrus fragrance of forests affected immune systems according to Komori et al . (1995) while da Silva et al . (2007 observed that volatile oil from Zanthoxylum rhoifolium Lam leaves and certain terpenes (α-humulene, β-caryophyllene, α-pinene, and β-pinene) to exhibit anti-tumor effects. Grassmann et al . (2003) reported the essential oil from Pinus mugo to show antioxidative properties.

Due to the constructive relationship between forests and the release of phytoncides in the atmosphere, a decline in forest cover means the lack of phytoncides or loss of human immunity (Sen, 2021, 2022). A study conducted in India during COVID revealed that a greater share of red zones (most-affected areas) were recorded in poor forest cover states and the highest percentage of green zones (COVID-19-free areas) were recorded in those states and Union territories having rich forest area. These findings conclusively prove that presence of forests definitely reduced the spread of the deadly disease. If the deforestation rate is significantly controlled then humans can fortify themselves against pandemic diseases as COVID-19.

As human immunity is directly linked with forests, trees and greenery, they need to be used for pandemic management and such areas need to be identified as zones of human protection or ‘Immunity Areas’ (Sen, 2023).

PLANTS AND COVID-19

In a survey conducted by iswas and Sen (2020) during COVID pandemic it was revealed that houseplants and indoor plants brought emotional benefits and stability to 74% participants during the ‘lockdown’. More than 55% respondents reportedly wished for more plants in their homes during the isolation phase. People with no indoor plants and little natural light at home experienced negative emotions like anxiety, fear, worry and distress more frequently than those with indoor or houseplants (Sen, 2024b). Just over half the participants reported that the amount of time they spent caring for plants had increased during ‘lockdown’ while 63% confirmed that they wanted to devote more time to care and nurturance of plants once normalcy was restored.

Plants can be used as efficient environment cleaning system from pollutants due to a process called phytoremediation which may be executed by various techniques. Certain indoor plants are natural air filters as they purify by absorption, dilution, precipitation and filtration and may be considered low-cost remedy against indoor pollutants.

Research revealed that plants are capable of absorbing tiny airborne water vapour particles and have the ability to improve indoor humidity. Plants can control air humidity maintaining it at an intermediate level which subsequently can lower the viability of SARS-CoV-2 in liquid aerosols decreasing the efficiency of viral transmission. Experiments were performed showing the reduction of airborne pathogens by plants, which reported that indoor house plants are competent to reduce airborne microbes by 50%, compared to indoor spaces lacking plants. Plants could significantly decrease air microbiomes when compared to plant-free sites, providing a healthier environment and reducing the exposure risk of airborne diseases.

BIOPHILIA AND RESTORATIVEENVIRONMENT DESIGN

Psychologist, Erich Fromm, first used the word biophilia in 1964, when he described it as “the passionate love of life and all that is alive”. The iophilia Hypothesis proposed by biologist E.O. Wilson in his work ‘ iophilia’ in 1984 suggests that humans possess an inherent and intrinsic affinity for nature and the natural world and feel a necessity to connect with “nature on physical, mental and social levels.”

Restorative environment design is an approach which seeks to firmly re-establish positive connections between nature and humanity (Sen, 2022). A concept introduced by Professor Stephen R. Kellert in 2005, it focuses on promoting overall health and wellbeing by incorporating natural environment for restorative healing. Not only does the concept emphasize environmental sustainability but also biophilic design methods to reduce undesirable impacts on the environment (Sen, 2010b, 2014). The Alnarp Rehabilitation Garden in Sweden is a fine example of an outdoor space created and designed for individuals with stress-related mental disorders and depression (Ivarsson and Grahn, 2010). It is actually a living laboratory, a part of Swedish University of Agricultural Sciences dedicated to healing people with nature-based rehabilitation. The garden is expertly designed so that it offers therapeutic support to a wide cross section of people suffering from mental ailments. Another example of biophilic design is in Future Sølund in Copenhagen, Denmark, addressing the problem of social disconnectedness in retired seniors. With strategically designed spatial layout, interiors and landscape the project aims at complete wellness and mental health of the community.

De Hogeweyk in the Netherlands is possibly the world’s first cognitively friendly home for patients of Alzheimer’s disease. The traditional nursing home has given way to a small community resembling the social environment of real life. Such innovative models improve the quality of life of patients besides slowing down the progress of Alzheimer’s. With its distinctive environmental design and humane approach, this organization serves as a significant reference for the elderly care homes and centres globally (Li et al., 2025)

The Sanjaynagar slum project in Maharashtra, India exemplifies the concept of restorative environment design for the low income group. Effectively combining restorative environment design with urban renewal, the project aims at sustainable community development and overall health and well-being of residents.

A tremendous urge to seek interaction with nature during times of disaster, crisis and stress is referred to as Urgent iophilia. In a work by MacKinnon et al. (2022) in New Zealand it was reported that people visited urban green spaces more frequently during lockdowns, the main reason being mental wellbeing followed by recreation. This study well indicated that residents used urban green spaces for their health and wellness benefits, thus conclusively proving the principles of urgent biophilia.

ECOTHERAPY AND PHYTOTHERAPY

Ecotherapy, Nature Therapy or Green Therapy is the applied practice of Ecopsychology and is an all inclusive term for activities which integrate human-nature interactions and relationships for improvement of human health and wellness. While ecotherapy focuses on the total mind-body-spirit relationship, its theoretical basis has several viewpoints including biophilia, restorative environmental theory and attention restoration theory. esides reconnecting people with nature eco-therapeutic activities can vary from psychotherapy in outdoor spaces to gardening and meditation amidst nature to birdwatching (Harrison et al ., 2023). All such activities are executed with an ecological consciousness and nature with natural settings is an integral part of the healing process. Though ecotherapy is commonly used in the context of healthcare, it may be also successfully administered in education or community-based settings ( lackburn et al ., 2025).

Phytotherapy derived from ‘phyton’ (plant) and ‘therapeia’ (treatment) is the practice of using plants or plant-derived substances as medicine. For instance, aspirin was first noted as early as 2500 C from the bark of willow trees and subsequently formed into a drug in 1897. Morphine and codeine derived from opium and poppy respectively are some other examples. Phytotherapy or herbalism may involve the entire plant, plant extract or specific plant compounds. It may come in various forms as tinctures, pills, capsules, ointments, compresses and tea. Phytopharmaceuticals or phytomedicines are plant/herb based medicines which in US are sold as dietary supplements. eta-sitosterol, fish oil with omega-3 fatty acids, ginger, green tea, probiotics, soy products are some examples of phytotherapies.

GREEN EXERCISE

Plants when strategically kept can reduce noise levels and act as a natural sound barrier making the desired space more calm and tranquil. Thus plants may be incorporated into spaces for yoga and meditation. While choosing plants for yoga and meditation we must look for low-maintenance options (succulents, snake plant) which are also aesthetically pleasing (peace lily, Croton). For aromatherapy we can opt for plants like jasmine, geranium and herbs.

The methods of incorporation could be through aromatherapy (as essential oils used in massage or warm bath), incense, intelligent placement of plants (creating calm and soothing environment) and herbal tea (adding lavender or chamomile before or after exercise).

Practicing yoga outdoors forms a powerful connection – the self with the earth. This connection is particularly healing and has strong therapeutic effects curing inflammation and improving sleep. The open space amidst nature can enhance breath awareness, deeper more conscious breaths improving relaxation. The large open outdoors in nature provides a holistic environment that harmonizes the mind-body-soul focus of yoga, thus forming the perfect mind-body-soul alignment. Nature serves as a mirror for self-reflection, infusing contemplation of personal cycles of growth and transformation The resilience and adaptability of Nature can inspire practitioners to accept their own life journeys

Plant gazing is sitting in front of a chosen plant with controlled breathing and concentration focusing on communication with the plant. Plant immersion is not only focusing on a particular plant for a certain span of time (from 3 days to a few weeks) but also bringing elements of the plant into life. For example, a rose immersion might involve drinking rose tea, bathing in rose petals or rosewater, applying rose essential oil, drawing with rose and meditating with rose. Dreaming with plants consist of placing plants under the pillow or drinking herbal tea before going to bed. When we intensify our relationship to nature we usher in their power, wisdom and resilience into our daily lives and make way for superior things to grow and happen.

CONFLICTS OF INTEREST

The author declares no conflicts of interest.