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The physiological and psychological human health benefits of urban forests Kovac, George Apr 22, 2016

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  The physiological and psychological human health benefits of urban forests   George Kovac FRST 497 April 22, 2016       Abstract  The accelerating movement of urbanization poses a threat to our natural forests. Along with the rapid loss of forests, there are increasing health concerns exhibited in developed countries. This leaves society with a major challenge that must be addressed. These challenges can be solved by using urban forests. Society can use the forests as a resource to improve human health. The aim of this literature review is to analyze the various human health benefits derived from urban forests. This is accompanied by a secondary objective to promote the use of our urban forests. I will examine the physiological and psychological benefits obtained from urban forests from various case studies. The health benefits received from these forests will be divided amongst three sections of study. The first section will focus on the health benefits received from viewing a forested environment in correlation to an urban environment. The second section will review the health benefits gained from the ancient technique of forest therapy. The final section will focus on the key components of urban parks and the perceptions individuals have of them.    2 Table of Contents Abstract .....................................................................................................................................1 Introduction...............................................................................................................................3 Health Benefits of an Urban Forest Environment ................................................................4 Forest Therapy ......................................................................................................................6 Park Components ..................................................................................................................8 Discussion ................................................................................................................................ 10 Conclusion ............................................................................................................................... 12 References................................................................................................................................ 14           3 Introduction   During past centuries, there has been movement of human populations into urban environments (Pretty et al, 2005). In the upcoming decade, the number of individuals living in urban environments will exceed those living in rural areas (Pretty et al., 2005). This movement towards urbanization poses a direct threat to our urban forests, causing their functions and structures to transform (Zhang 2015). The current rate of urban area expansion in Europe for instance, is greater than any other types of land use change (Eigenbrod et al., 2011). Urbanization is continuing to grow and society ought to look for solutions to save urban forests.   Along with the increasing rate of urbanization, there is the rising concern of human health issues such as, obesity, and stress related illnesses. Physical inactivity is one of the main causes of death in developed countries (O’Brien, 2006). The lack of physical activity in developed countries will only further develop obesity and other diseases (O’Brien, 2006). Exposure to stress through daily interactions in cities poses a serious threat to individuals’ mental health (Joung et al., 2015). The combined forces of increasing urbanization and health problems in society leads to a problem that cannot be neglected any longer.  This problem holds a unique opportunity for urban forests: to use the forests as a resource to improve human health. This is accompanied by a secondary objective to promote the expansion, management, and use of our urban forests. The goal will be achieved by acknowledging the proven human health benefits provided by urban forests.  In this essay, I will examine the physiological and psychological benefits obtained from urban forests. However, I will not examine medicinal products derived from the forest. The main body of this essay will be divided into three sections. The first section will focus on the health benefits received from viewing a forested environment in correlation to an urban environment. The second section will review the health benefits gained from the ancient technique of forest therapy. The final section will focus on the key components of urban parks and the perceptions individuals have of them.    4 Health Benefits of an Urban Forest Environment   The exposure to stress through daily interactions in cities poses a serious threat to an individual's mental health (Joung et al., 2015). Mental health issues are becoming more prominent in today’s society. A possible solution lies in the increased use of urban forests. Urban forests and green spaces in the urban environment have been proven to provide people with increased feelings of well-being and to reduce stress-related health issues. Historically, natural scenic settings have had a tendency of reducing stress in comparison to urban environments (Velarde et al. 2007). In this section, I will review several studies performed by various research institutes analyzing the health benefits from viewing a forest environment in comparison to an urban environment.   The study performed by Joung et al. (2015) examined prefrontal cortex activity when viewing an urban setting compared to a forest landscape. The urban environment that was used for this study was located in Yuseong-gu, Daejeon Metropolitan City, Korea. Participants were asked to view the urban environment from the 4th floor of a chosen building. The forests of Dowon-ri, Toseong-myun, Goseong-gun, Gangwon-do, Korea were used for the forest landscape of this study. Near-infrared spectroscopy (NIRS) was used to monitor the physiological reaction of the participants by measuring “changes in the hemoglobin concentration in the prefrontal cortex” (Joung et al., 2015).  To evaluate the psychological effects participants were required to fill out a semantic differential (SD) method questionnaire and a profile of mood state (POMS) before and after the experiment. The SD method is commonly used to evaluate scenery on a 13-point scale and uses different feeling adjectives (e.g., soothing, comfortable, and natural) to evaluate scenery.  The POMS questionnaire is used to evaluate participants’ emotions. It incorporates 30 questions based on emotions such a “tension and anxiety”, “depression and anger”, “vigor”, etc. (Joung et al., 2015).  The study comprised of participants viewing the scenery for 15 minutes then completing the required assessments. While viewing the various sceneries, NIRS measurements were taken. After compiling the results, it was evident that the prefrontal cortex activity was more stable and more relaxed state when viewing forest scenery compared to when the individual was viewing an  5 urban setting. Also, the oxy-Hb concentration level was observed to be much lower when viewing the forested environment. The lower the oxy-Hb concentration level, the more relaxed an individual’s state of mind (Joung et al. 2015).  Joung et al. (2015) also examined how participants felt while viewing each type of scenery. The participants when viewing the forest scenery experienced feelings of comfort, natural, and soothing. In general, feelings of the participants were more positive when viewing the forest environment rather than the urban environment.  Other work on comparing the benefits of viewing a forest compared to an urban environment was conducted by Kaplan (2001). This study found viewing green spaces through windows had a restorative impact on people. It has been reported that there is a correlation between windows and job satisfaction (Kaplan, 2001). Generally, well-being of workers, prisoners and hospital patients with windows have been higher than those for whom windows and views of scenic areas were not available.  The study was comprised of participants from six apartment complexes in Ann Arbor, Michigan.  A portion of these selected apartments were located in the urban environment that incorporated views such as: paved areas, parked cars, buildings and other built infrastructure. The other half of the apartment complexes had views of a park that included a stream, woodland area and grasslands. The apartment complexes selected were approximately the same height (not exceeding three stories) and generated the same rental income (approximately $500/month). The study was constructed using surveys that had a scale from 1-5, with 55 being the highest quality. Also, the study included a booklet of photographs of views taken from windows within each apartment complex. Participants were asked to rate these photos on a 5-point scale as well. The photographs were placed into four different categories: cars, structures, landscape and nature (Kaplan, 2001).  The unmanaged woodland was the most preferred view.  The overall preference score was highest for the nature scenes (3.99), followed by landscape scenes 3.07, structures (1.76) and cars (1.91). These ratings were used to assess overall well-being of individuals and their satisfaction with nature and their neighborhoods. Nature scenes provided individuals with the greatest improved well-being. Feelings of less distraction and overall improved satisfaction were also observed when viewing a nature scene relative to other possible choices. Another  6 psychological benefit that was observed was mental fatigue was reduced when individuals view these natural scenes in comparison to others (Kaplan, 2001). Pretty et al. (2005) examined the effect of green exercise on individuals. Participants were given 4 photographs to view while engaging in physical activity. The photographs provided were categorized into the following views: urban pleasant, urban unpleasant, rural unpleasant and rural pleasant. All of the participants took part in a fairly light workout that was 20 minutes long. During this time an increase in overall blood level was observed in the participants when viewing pleasant and unpleasant urban photographs, while both pleasant and unpleasant rural photographs decreased blood pressure.  Rural pleasant scenes had the greatest decrease in blood pressure level. This study showed that exercising in a pleasant environment had a greater impact on health than just exercising alone. Forest Therapy   A common theme found throughout the studies that will be discussed below is how the ancient practice of forest therapy provides individuals with various health benefits. This practice has been historically used as a stress management tool in Japan where it is also referred to as “forest bathing”, consisting of visits to a forest for the main “purpose of relaxation and recreation by breathing in volatile substances” (Li et al, 2007).  A study of the impacts of forest walking on autonomic nervous system activity in the middle aged hypertensive individuals was performed by the Song et al. (2015) in Agematsu, Japan. The study consisted of twenty Japanese men, with average age of 58yrs (. The physiological aspects of the study such as heart rate was measured using a wearable electrocardiogram sensing system. Individuals were also tested psychologically. These individuals were required to fill out SD and POMS questionnaires. The participants were required to walk on a predetermined course for 17 minutes, with equal amounts of forested and urban environments.  The individuals did exert equal energy in both environments. However, there was a significant health benefit shown while walking in the forest compared to the urban environment.  The overall moods of individuals who took part in this experiment were more positive in the forest compared to the urban environment.  The results from the SD method  7 questionnaire showed participants felt more comfortable, relaxed and natural. Walking in the forest also showed an increase in psychological relaxation (Song et al., 2015). Song et al. (2015) also stated that a lower heart rate was experienced when individuals walked in the forest setting. Also walking in the forest increased parasympathetic nerve activity and decreased heart rate. A simple short walk through the forest had both physiological and psychological benefits that can aid in reducing stress and increasing relaxation of the human psyche.   Li et al. (2008) examined the number and activity of natural killer cells and intracellular anti-cancer proteins present when visiting a forest in comparison to an urban setting. Natural killer cells are a type of lymphocyte cell, that respond to tumor and virus-infected cells. This experiment focused on individuals concentrating on breathing in the volatile substances surrounding them and walking through the forest, referred to as “forest bathing” (2008). The experiment consisted of taking participants to a forest for a particular set length and later on measuring the side effects and comparing them to a trip in the city. The trip occupied 3 days, with each individual staying in the forest for 2 hours at a time. Blood samples were then drawn from each individual and examined in the laboratory. Individuals were required to walk 5 km/day .The forest trip proved to be effective and increased the overall natural killer activity and number of cells. Participants also experienced an increase in intracellular anti-cancer proteins. However, the physiological effects from the forest lasted up to 7 days.  Further studies have shown the physiological and psychological benefits of “forest bathing”. Ochiai et al. (2015) examined the physiological and psychological effects forests have on middle aged females. Their study was comprised of 17 middle-aged females with ages ranging from 40-73yrs. To measure the physiological effects of the forest bathing experiment Blood pressure, pulse rate readings, and salivary cortisol samples were taken to measure the physiological effects of the forest bathing experiment. The psychological tests were comprised of SD and POMS questionnaires. These questionnaires were completed before and after the forest therapy session (Table 1).     8 Table 1: Time schedule and list of activities to perform during therapy session (from Ochiai et al., 2015).    Lower pulse levels were recorded after the therapy session. Lower salivary cortisol levels, indicating lower stress levels, and lower blood pressure were also found following the forest therapy ((Ochiai et al., 2015).  The SD method showed participants recorded their feelings using adjectives such as comfortability, relaxation and natural feeling. The POMS questionnaire indicated participants felt less “tension-anxiety” and positive “vigor” was higher. This indicated that the forest therapy session provided psychological benefits to the participants (Ochiai et al., 2015).  Park Components   Individuals can improve their health by participating in activities in urban forests, particularly recreational activities in parks and forests nearby cities. Such activities include walking, jogging, and biking (Douglas et al., 2010). The perception an individual has of a park also impacts on the type of physical benefits received (Lee and Lee, 2015). As the words of  9 Micheal de Certeau: “The act of walking is to the urban system what the speech is to the language” (Douglas et al., 2011). The issue of increasing physiological and psychological health issues in society can be partially solved by using urban parks as possible rehabilitation facilities. The studies presented below illustrate how park components and perceptions can have a positive effect on individuals’ health.   Parks play a major role in the physical activity level of an individual. Historically, they have been referred to as “the lungs of the city” (Douglas et al, 2010). Parks provide a haven for individuals trying to escape the daily commotion occurring in the rest of the city. These more natural areas allow individuals to relax or provide an outlet for physical activity. There are two key components that encourage an individual to partake in physical activities in parks: (1) the proximity of a park to an individual; and (2) the specific park features (Douglas et al, 2010). Close proximity to a park is referred to lying within 1 km from a person’s home (Douglas et al, 2010 via Cohen et al, 2007). Proximity to a park has shown to improve physical health. Individuals that live near parks in an urban environment have been shown to have higher physical activity levels. This holds truth when considering older adults who generally spend more time being active at a park if their home is in close proximity to the park. Types of activities include walking and biking to the park (Douglas et al, 2010).  Researchers have found that physical activities of young children were highest amongst park users. They also observed different ethnic groups use parks for different purposes. The aesthetic appeal of a park was the main factor in deciding in which park to use for physical activity. Woodlands, water features, and landscaping were the desired features; the more natural the park, the higher people’s preference for it (Douglas et al, 2010).  Lee and Lee (2015) examined the difference in perception between mountainous forests and urban forests with respect to natural experience, recreation and health. This experiment was performed in the urban forest and mountain forests of Freiburg (Germany), Vienna (Austria), and Zurich (Switzerland). They focused their study on the satisfactory level of the nature experience, outdoor recreational activities and if the natural experience had an effect on physical and mental health. The experiment was comprised of conducting a survey targeting residents in the chosen cities. Participants were asked to assign points to the given topics (nature experience, satisfaction level of recreational activity, mental and physical health) (Table 2). The overall nature  10 experience was greater in mountain forests (4.36) compared to an urban forest (3.36). However, in Vienna both mental and physical health benefits were rated higher in urban forests, and in Zurich physical health was rated higher in urban forests. Greater physical benefits were perceived in the urban forests. The authors concluded that participants did perceive a difference in the overall health benefits of mountain forests compared to urban forests.   Table 2: Characteristics of survey respondents (from Lee and Lee, 2015).   Discussion  A common theme observed throughout the literature review was how the health benefits have been proven through viewing a forested environment in comparison to urban environment. The study conducted by Joung et al. discovered that participants experienced more positive feelings and emotions when viewing a forest environment in comparison to an urban setting (2015). The physiological benefits of this study showed lower oxy-Hb concentration levels in participants resulting in a more relaxed mind (Joung et al., 2015).  Conjointly, Kaplan observed participants obtaining health benefits from viewing a forest environment in comparison to an urban environment (2001). The study proved that overall well-being and satisfaction was achieved (Kaplan 2001). The study conducted by Pretty at el.  11 examined the health benefits retrieved from viewing various settings while participating in physical exercise (2005).  The results observed showed a decrease in blood pressure, resulting in overall improvement of cardiovascular health (Pretty et al., 2005).   Additionally, physiological and psychological benefits have also been shown from forest bathing. The physiological benefits experienced through Song et al. showed participants felt more comfortable, relaxed and natural during their walk in the forest (2015). Participants also experienced physiological health benefits such as lower heart rate and increased parasympathetic nerve activity (Song et al, 2015). Li et al. discovered during their study that participant’s natural killer activity levels and number of cells increased (2008). The results of the study also showed an increase in intracellular anti-cancer proteins (Li et al. 2008). The study conducted by Ochiai et al. also used forest bathing to display health benefits derived from the forest.  The observations made in Ochiai et als’ study resulted in lower pulse levels (2015). Lower salivary cortisol levels and blood pressures were also shown in the participants following the forest therapy session (Ochiai et al, 2015). The change in lower salivary cortisol levels and blood pressures provides evidence in reduced stress levels (Ochiai et al).  Park components and the general perception of a park have positive health effects on individuals. There are a variety of health benefits that urban forest offer. For example, as stated by Douglas et al. simply the proximity of a park increases an individual physical activity. An individual’s likelihood of part taking in activities physical activities such as walking, biking and jogging (Douglas et al., 2010). The secondary factor that affects physical activity levels in parks is the different type of components found in the park (Douglas et al., 2010). The correlation observed was the more natural the park appeared the greater the physical activity level was experienced.  A person’s perception of physical benefits in urban forests such as parks was greater in urban forest than mountainous forests (Lee JH and Lee DJ, 2015). This was evident in the study conducted by Lee JH and Lee DJ were benefits such as increase in physical activity was experienced (2015).   However, one research study although acknowledging the health benefits received from forests have conducted studies in where forests actually cause health problems. Tomalak et al. states that parks can threaten human life and cause health problems (2010). Health issues such as  12 allergic responses from pollen producing plants can occur in urban forest. Incidences such as wildlife attacks and pathogens transmitted by forest mammals have been noted (Tomalak et al 2010). Anthropogenic factors such as falling trees are a potential threat to humans when participating in activity in an urban forest (Tomalak et al 2010).  The health benefits listed above provide an incentive for individuals to increase their activity levels in urban forests. However, quantifying the health benefits of urban forest is a relatively new genre, where further studies are needed to investigate different components of the field. The physiological studies performed were oriented towards the effects on cardiovascular health and the nervous system. Future research could be guided towards the effects of forests on the respiratory system and the muscular system, an area of study that lacks substance. For example, a primary area of study that can be further investigated is the effects of walking in a forests compared to an urban environment at the muscular level. A possible research institute can look at physiological aspect of walking in the forest in comparison to an urban environment, through techniques such as forest bathing.     Conclusion    Individuals that are currently dealing with psychological or physiological health issues should consider using urban forests as a viable option for curing their illness. This literature review examined the various health benefits obtained from our urban forests. It was shown the health benefits were gained through a variety of factors such as viewing a forested environment in correlation to an urban environment, forest therapy, park components and perceptions.  The general health benefits experienced from viewing a forested environment in comparisons to an urban environment were lower oxy-HB concentration levels, decrease in blood pressure, positive feelings and emotions. Forest therapy studies were able to provide  13 participants with positive feelings, lower heart rate, lower blood pressure, lower salivary levels, increase parasympathetic nerve activity, increase natural killer cells and increased intracellular anti-cancer proteins. Park components and the perception of parks influenced the increased the physical activity levels of individuals. The evidence supporting health benefits are responsible for an individual’s decrease in stress levels, improved cardiovascular health and an increase in physical activity.  The combination of these various health benefits should incentivize individuals to increase their activity levels in urban forests, especially with urbanization and health issues becoming a growing concern. This holds true especially with individuals dealing with health issues such as obesity, deprecation, stress, high blood pressure etc. The alternative of going to a park instead of a gym can also increase motivation in certain individuals. Society ought to place stronger emphasis on urban forests as a solution for addressing certain health issues.                14 References  Douglas, I., Goode, D., Houck, M., & Wang, R. (2010). Handbook of urban ecology (1st ed.).  Hoboken: Routledge. Retrieved from http://www.eblib.com Eigenbrod, F., Bell, V. A., Davies, H. N., Heinemeyer, A., Armsworth, P. R., & Gaston, K. J.   (2011). The impact of projected increases in urbanization on ecosystem services.    Proceedings: Biological Sciences, 278(1722), 3201-3208. doi:10.1098/rspb.2010.2754 Joung, D., Kim, G., Choi, Y., Lim, H., Park, S., Woo, J., & Park, B. (2015). The prefrontal cortex activity and psychological effects of viewing forest landscapes in autumn season.   International Journal of Environmental Research and Public Health, 12(7), 7235-7235. doi:10.3390/ijerph120707235 Kaplan, R. (2001). The nature of the view from home: Psychological benefits. Environment and   Behavior, 33(4), 507-542. doi:10.1177/00139160121973115 Lee, J., & Lee, D. (2015). Nature experience, recreation activity and health benefits of visitors in   mountain and urban forests in vienna, zurich and freiburg. Journal of Mountain Science,  12(6), 1551-1561. doi:10.1007/s11629-014-3246-3 Li, Q., Morimoto, K., Kobayashi, M., Inagaki, H., Katsumata, M., Hirata, Y.. . Krensky, A.  (2008). Visiting a forest, but not a city, increases human natural killer activity and    expression of anti-cancer proteins. International Journal of Immunopathology and  Pharmacology, 21(1), 117-127 O’Brien, L. (2006). " Strengthening heart and mind": using woodlands to improve mental and   physical well-being. UNASYLVA-FAO-, 57(2), 56. Ochiai, H., Ikei, H., Song, C., Kobayashi, M., Miura, T., Kagawa, T.. . Miyazaki, Y. (2015).   Physiological and psychological effects of a forest therapy program on middle-aged   females. International Journal of Environmental Research and Public Health, 12(12),   15222-15232. doi:10.3390/ijerph121214984  15 Pretty, J., Peacock, J., Sellens, M., & Griffin, M. (2005). The mental and physical health    outcomes of green exercise. International Journal of Environmental Health Research,   15(5), 319-337. doi:10.1080/09603120500155963 Song, Chorong, et al. (2015):  "Effect of Forest Walking on Autonomic Nervous System Activity   in Middle-Aged Hypertensive Individuals: A Pilot Study." International journal of   environmental research and public health 12.3, 2687-2699. Tomalak, M., Rossi, E., Ferrini, F., & Moro, P. A. (2010). Negative Aspects and Hazardous   Effects of Forest Environment on Human Health. Forests, Trees and Human Health, 77- 124. Velarde, M., Fry, G., & Tveit, M. (2007). Health effects of viewing landscapes – landscape types   in environmental psychology. Urban Forestry & Urban Greening, 6(4), 199-212.    doi:10.1016/j.ufug.2007.07.001 ZHANG Dan ZHENG Haifeng REN Zhibin ZHAI Chang SHEN Guoqiang MAO Zhixia    WANG Peijiang HE Xingyuan. (2015). Effects of forest type and urbanization on carbon   storage of urban forests in changchun, northeast china. 中国地理科学:英文版, 25(2),   147-158. doi:10.1007/s11769-015-0743-4   

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