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How Might Contact with Nature Promote Human Health? Promising Mechanisms and a Possible Central Pathway


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How might contact with nature promote human health? Myriad studies have linked the two; at this time the task of identifying the mechanisms underlying this link is paramount. This article offers: (1) a compilation of plausible pathways between nature and health; (2) criteria for identifying a possible central pathway; and (3) one promising candidate for a central pathway. The 21 pathways identified here include environmental factors, physiological and psychological states, and behaviors or conditions, each of which has been empirically tied to nature and has implications for specific physical and mental health outcomes. While each is likely to contribute to nature's impacts on health to some degree and under some circumstances, this paper explores the possibility of a central pathway by proposing criteria for identifying such a pathway and illustrating their use. A particular pathway is more likely to be central if it can account for the size of nature's impacts on health, account for nature's specific health outcomes, and subsume other pathways. By these criteria, enhanced immune functioning emerges as one promising candidate for a central pathway between nature and health. There may be others.
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published: 25 August 2015
doi: 10.3389/fpsyg.2015.01093
Edited by:
Marc Glenn Berman,
The University of Chicago, USA
Reviewed by:
Sumitava Mukherjee,
Indian Institute of Management,
Ahmedabad, India
Teresa Helen Horton,
Northwestern University, USA
Ming Kuo,
Landscape and Human Health
Laboratory, Department of Natural
Resources and Environmental
Sciences, University of Illinois at
Urbana-Champaign, 1101 West
Peabody Drive, MC-637 Urbana, IL
61801, USA
Specialty section:
This article was submitted to
Cognitive Science,
a section of the journal
Frontiers in Psychology
Received: 04 March 2015
Accepted: 16 July 2015
Published: 25 August 2015
Kuo M (2015) How might contact with
nature promote human health?
Promising mechanisms
and a possible central pathway.
Front. Psychol. 6:1093.
doi: 10.3389/fpsyg.2015.01093
How might contact with nature
promote human health? Promising
mechanisms and a possible central
Ming Kuo
Landscape and Human Health Laboratory, Department of Natural Resources and Environmental Sciences, University of
Illinois at Urbana-Champaign, Urbana, IL, USA
How might contact with nature promote human health? Myriad studies have linked the
two; at this time the task of identifying the mechanisms underlying this link is paramount.
This article offers: (1) a compilation of plausible pathways between nature and health;
(2) criteria for identifying a possible central pathway; and (3) one promising candidate
for a central pathway. The 21 pathways identified here include environmental factors,
physiological and psychological states, and behaviors or conditions, each of which has
been empirically tied to nature and has implications for specific physical and mental
health outcomes. While each is likely to contribute to nature’s impacts on health to some
degree and under some circumstances, this paper explores the possibility of a central
pathway by proposing criteria for identifying such a pathway and illustrating their use.
A particular pathway is more likely to be central if it can account for the size of natur e’s
impacts on health, account for nature’s specific health outcomes, and subsume other
pathways. By these criteria, enhanced immune functioning emerges as one promising
candidate for a central pathway between nature and health. There may be others.
Keywords: natural environment, greenspace, immune, mechanism, mental health, literature review
Contact with nature has been tied to health in a plenitude of studies. Time spent in and
around tree-lined streets, gardens, parks, and forested and agricultural lands is consistently
linked to objective, long-term health outcomes. The less green a person’s surroundings, the
higher their risk of morbidity and mortality even when controlling for socioeconomic
status and other possible confounding variables. The range of specific health outcomes tied
to nature is startling, including depression and anxiety disorder, diabetes mellitus, attention
deficit/hyperactivity disorder (ADHD), various infectious diseases, cancer, healing from surgery,
obesity, birth outcomes, cardiovascular disease, musculoskeletal complaints, migraines, respiratory
disease, and others, reviewed below. Finally, neighborhood greenness has been consistently tied to
life expectancy and all-cause mortality (see Table 3 in the Supplementary Materials).
These findings raise the possibility that such contact is a major health determinant, and that
greening may constitute a powerful, inexpensive public health intervention. It is also possible,
however, that the consistent correlations between greener surroundings and better health reflect
self-selection healthy people moving to or staying in greener surroundings. Examining the
Frontiers in Psychology | www.fro 1 August 2015 | Volume 6 | Article 1093
Kuo Nature-health mechanisms
potential pathways by which nature might promote health seems
paramount both to assess the credibility of a cause-and-effect
link and to suggest possible nature-based health interventions.
Toward that end, this article offers: (1) a compilation of plausible
pathways between nature and health; (2) criteria for identifying a
possible central pathway; and (3) one promising candidate for a
central pathway.
How Nature Might Promote Health:
Plausible Pathways
How might contact with nature promote health? To date,
reviews and studies addressing multiple possible mechanisms
(Groenewegen et al., 2006, 2012; Sugiyama et al., 2008;
de Vries et al., 2013; Hartig et al., 2014)havefocused
on four air quality, physical activity, stress, and social
integration. But the burgeoning literature on nature benefits
has revealed an abundance of possible mechanisms: as Figure 1
shows, this review identifies 21 plausible causal pathways
from nature to health. Each has been empirically tied to
contact with nature while accounting for other factors, and
is empirically or theoretically tied to specific health outcomes
(for details on the scope of this review, see Table 1 in the
Supplementary Materials). The 21 pathways identified here
include environmental factors, physiological and psychological
states, and behaviors or conditions, and are summarized below
(for more details on each of these pathways, see Table 2 in the
Supplementary Materials).
Envir onmental Conditions
Some of the plausible pathways from contact with nature
to improved health stem from specific environmental
conditions. Natural environments contain chemical and
biological agents with known health implications. Many
plants give off phytoncides
antimicrobial volatile organic
compounds — which reduce blood pressure, alter autonomic
activity, and boost immune functioning, among other effects
(Komori et al., 1995; Dayawansa et al., 2003; Li et al., 2006,
2009). The air in forested and mountainous areas, and near
moving water, contains high concentrations of negative air ions
(Li et al., 2010), which reduce depression (Terman et al.,
1998; Goel et al., 2005), among other effects (Table 2 in the
Supplementary Materials). These environments also contain
mycobacterium vaccae
, a microorganism that appears to boost
immune functioning (see Lowry et al., 2007 for review).
Similarly, environmental biodiversity
has been proposed to
play a key role in immune function via its effects on the
microorganisms living on skin and in the gut, although the
evidence for this is mixed (Table 2 in the Supplementary
The sights
and sounds of nature also have important
physiological impacts. Window views and images of
nature reduce sympathetic nervous activity and increase
parasympathetic activity (e.g., Gladwell et al., 2012; Brown
et al., 2013), restore attention (e.g., Berto, 2005), and promote
healing from surgery (Ulrich, 1984). Sounds of nature played
over headphones increase parasympathetic activation (Alvarsson
et al., 2010). These sympathetic and parasympathetic effects
drive the immune system’s behavior (for review, see Kenney and
Ganta, 2014), with long-term health consequences.
In built environments, trees and landscaping may promote
health not only by contributing positive factors like phytoncides
but also by reducing negative factors. Air pollution
is associated
with myocardial inflammation and respiratory conditions
(Villarreal-Calderon et al., 2012). High temperatures
cause heat exhaustion, heat-related aggression and violence,
and respiratory distress due to heat-related smog formation
(Anderson, 2001; Akbari, 2002; Tawatsupa et al., 2012). And
affects physical and mental health (e.g., Groves et al.,
1993). Vegetation filters pollutants from the air (although see
Table 2 in the Supplementary Materials for details), dampens the
urban heat island (e.g., Souch and Souch, 1993), and appears
to reduce violence (Table 2 in the Supplementary Materials for
Physiological and Psychological States
Some of the plausible pathways between contact with nature and
health involve short-term physiological and psychological effects,
which, if experienced regularly, could plausibly account for long-
term health effects.
Blood tests before and after walks in different environments
reveal that levels of health-protective factors increase after
forest but not urban walks. Didehydroepiandrosterone
increases after a forest walk (Li et al., 2011); DHEA has cardio
protective, anti-obesity, and anti-diabetic properties (Bjørnerem
et al., 2004). Similarly, time in nature increases adiponectin
(Li et al., 2011), which protects against atherosclerosis, among
other things (Table 2 in the Supplementary Materials), and
the immune system
s anti-cancer (so-called Natural Killer, or
NK) cells and related factors (Table 2 in the Supplementary
Materials). NK cells play important protective roles in cancer,
viral infections, pregnancy, and other health outcomes (Orange
and Ballas, 2006).
Further, walks in forested, but not urban areas, reduce
the levels of health risk factors, specifically inflammatory
cytokines (Mao et al., 2012), and elevated blood glucose
et al., 1998). Inflammatory cytokines are released by the
immune system
in response to threat, and have been implicated
in diabetes, cardiovascular disease, and depression (Table 2 in the
Supplementary Materials). Chronically elevated blood glucose
carries multiple health risks, including blindness, nerve damage,
and kidney failure (Sheetz and King, 2002). The powerful effects
of a walk in a forest on blood glucose are particularly striking
(Table 2 in the Supplementary Materials for review).
Contact with nature has a host of other physiological
effects related to relaxation
or stress reduction (Table 2 in the
Supplementary Materials). The experience of nature helps shift
individuals toward a state of deep relaxation and parasympathetic
activity, which improves sleep (El-Sheikh et al., 2013), boosts
immune function in a number of ways (Kang et al., 2011), and
counters the adverse effects of stress on energy metabolism,
insulin secretion, and inflammatory pathways (Bhasin et al.,
2013). Evidence suggests this pathway contributes substantially to
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Kuo Nature-health mechanisms
FIGURE 1 | The nature-health link: filling in the details. This Figure
summarizes the state of the scientific literature on nature and health, listing (1)
the active ingredients” in nature that have been identified as having impacts on
health or health antecedents; (2) physiological/psychological states, behaviors,
and conditions tied to both nature and health; and (3) specific health outcomes
that have been tied to nature (controlling for socioeconomic variables). Note that
physical activity (in brackets) is only sometimes tied to nature; and that allergies,
asthma, and eczema are sometimes positively and sometimes negatively tied to
nature. DHEA: didehydroepiandrosterone; acute UTI: acute urinary tract
infection; ADHD: attention deficit hyperactivity disorder; IDIC: infectious disease
of the intestinal canal; MUPS: medically unexplained physical symptoms; URTI:
upper respiratory tract infection.
the link between nature and health (Table 2 in the Supplementary
Three psychological effects of nature experiences of awe
(Shiota et al., 2007), enhanced vitality (Ryan et al., 2010), and
attention restoration (Table 2 in the Supplementary Materials)
offer additional possible pathways between nature and health.
Regular experiences of awe are tied to healthier, lower levels of
inflammatory cytokines (Stellar et al., 2015); the ties between
nature and awe, and awe and cytokines, respectively, may help
explain the effects of forest walks on cytokines above. Similarly,
feelings of vitality predict resistance to infection (Cohen et al.,
2006) and lowered risk of mortality (Penninx et al., 2000).
Attention restoration could theoretically reduce accidents caused
by mental fatigue and, by bolstering impulse control, reduce risky
health behaviors such as smoking, overeating, and drug or alcohol
abuse (Wagner and Heatherton, 2010).
Behaviors and Conditions
The remaining four possible pathways between contact with
nature and health identified here involve behaviors and
conditions: physical activity
,obesity, sleep,andsocialties.
Physical activity is a major contributor to health (Centers for
Disease Control and Prevention [CDC], 2015), and intuitively
we associate green space with physical activity but empirically
this relationship is surprisingly inconsistent (Table 2 in the
Supplementary Materials) and may hold only under certain
conditions and for certain populations. Perhaps still more
surprising, while greener residential areas do not consistently
predict physical activity, they do consistently predict lower
rates of obesity (for review, see Table 2 in the Supplementary
Materials); this suggests the pathway between nature and obesity
may depend less on natures effects on physical activity and more
on its effects on adiponectin, stress, and impulse control. Both
sleep and social ties are major contributors to health (Table 2 in
the Supplementary Materials); contact with nature contributes to
both better sleep (Morita et al., 2011; Astell-Burt et al., 2013)and
stronger social ties (see Table 2 in the Supplementary Materials
for review).
Exploring the Possibility of a Central
Each of the mechanisms above is likely to contribute to natures
impacts on health to some degree and under some circumstances.
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Kuo Nature-health mechanisms
Most likely, some pathways will play a larger role than others.
This paper explores the possibility that one or a few pathways
may explain the lion’s share of the link between nature and
health by proposing criteria for identifying central pathways and
illustrating the application of these criteria.
First, a pathway is more likely to be central if it can account
for the size of natures impacts on health. A study of over 345,000
people living in greener and less green residential surroundings
revealed large differences in the prevalence of disease; even
after controlling for socioeconomic status, prevalence for 11
major categories of disease was at least 20% higher among the
individuals living in less green surroundings (Maas et al., 2009).
For a single pathway to plausibly account for the bulk of the tie
between nature and health, the mechanism involved would need
to have substantial effects on health, and be substantially affected
by contact with nature.
Second, a pathway is more likely to be central if it can
account for specific health outcomes tied to nature. Although
health is often treated as a unitary construct in the nature-health
literature, poor health takes a multiplicity of separable, largely
independent forms. A pathway that leads to one health outcome
may not lead to others; for example, reduced air pollution may
lessen respiratory symptoms, but is not likely to affect ADHD
symptoms. A central pathway between nature and health should
to nature.
Third, a pathway is more likely to be central if it subsumes
other pathways. To the extent that multiple nature-health
pathways feed into a particular pathway between nature and
health, that pathway is more central to the relationship between
nature and health.
These three criteria can be applied to any given pathway to
determine its centrality. In this paper, they are applied to one
particular pathway: enhanced immune functioning.
Criterion #1: Accounting for the Size of the
Nature-Health Link
Determining whether a particular pathway can account for the
size of the nature–health link requires examining the effect sizes
for the nature–mechanism and mechanism–health relationships.
For the immune system, the existing literature reveals both these
effect sizes to be large.
Time spent in nature has substantial beneficial effects on
the immune system, raising positive indicators, and lowering
negative ones. Two 2-h forest walks on consecutive days
increased the number and activity of anti-cancer NK cells by 50
and 56%, respectively, and activity remained significantly boosted
even a month after returning to urban life 23% higher than
before the walks (Li, 2010). Moreover, extended time in a forest
decreased inflammatory cytokines implicated in chronic disease
by roughly one-half (Mao et al., 2012). Urban walks have no such
The immune system, in turn, has powerful effects on health.
The cytotoxic activity of NK cells is important in preventing
cancer in an 11-year study, the incidence of cancer among the
individuals in the middle and top third of cytotoxic activity was
roughly 40% less than that among individuals with low levels
of NK activity (Imai et al., 2000). NK cells also play important
health-promoting roles in fighting viral and other infections, in
autoimmune disorders, and in pregnancy (see Orange and Ballas,
2006 for review). Moreover, inflammatory cytokines are thought
to play an important role in a host of chronic diseases, including
diabetes, cardiovascular disease, and depression (Cesari et al.,
2003; Wellen and Hotamisligil, 2005; Dowlati et al., 2010).
It appears that enhanced immune function fulfills the first
criterion for a central pathway: it can account for the size of
natures apparent impacts on health.
Criterion #2: Accounting for the Specific
Health Outcomes Tied to Nature
Each specific health outcome tied to nature constitutes a testable
hypothesis for any proposed central pathway; the more specific
health outcomes a pathway can account for, the more central its
Contact with nature has been linked to a plethora of
specific health outcomes; in general, the more contact with
nature, the better the health outcome, even after controlling
for socioeconomic status and other factors. For each of the
following, available evidence points to a favorable impact: acute
urinary tract infections, anxiety disorder, ADHD, birth outcomes,
cancer, cardiovascular disease, depression, diabetes mellitus,
healing from surgery, infectious disease of the intestinal canal,
musculoskeletal complaints, medically unexplained physical
symptoms (MUPS), migraines, upper respiratory tract infections,
respiratory disease, and vertigo (for details, see Table 3 in the
Supplemental Materials). For allergies, asthma, and eczema, the
apparent impact of nature varies; depending on the specific
measures used and the place, the relationships are positive,
negative, or null (Table 3 in the Supplemental Materials).
To determine whether enhanced immune functioning could
account for these specific health outcomes, the literature on
immune functioning and each of the 18 specific outcomes
was collected and reviewed. Available evidence indicates that
enhanced immune functioning may be able to account, wholly
or partially, for all 18 (see Figure 2).
ward off infectious disease, protecting the body from bacterial,
parasitic, fungal, and viral infections (National Institutes of
Health [NIH], 2012). Thus enhanced immune function could
clearlyexplainwhycontactwithnature is tied to lower rates of
acute urinary tract infections, infectious disease of the intestinal
canal, and upper respiratory tract infections. Further, for health
outcomes with multiple possible origins, enhanced immune
function can account for cases with infectious origins — for
example, infectious forms of respiratory disease but perhaps
not forms of respiratory disease with non-infectious origins.
Similarly, enhanced immune function can account for MUPS and
vertigo with infectious origins (Bovo et al., 2006; Deary et al.,
2007, respectively).
Two other key roles of the immune system are to assist
in wound healing, and to seek out and destroy tumor cells.
Thus enhanced immune function can account for the effect of a
hospital view of nature on recovery from surgery (Ulrich, 1984),
as well as the relationship between residential greenness and
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Kuo Nature-health mechanisms
FIGURE 2 | Enhanced immune function as one possible central
pathway. All items in white text are currently known or have been
proposed to be causally tied to immune function. As the Figure
shows, enhanced immune function can account, at least partially, for
each of the specific health outcomes currently tied to nature and
may subsume, at least partially, all but two of the other pathways.
Other pathways may also contribute the nature-health link, and other
central pathways may exist.
lower rates of cancer (Li et al., 2010). Further, the immune system
governs inflammation, which is involved in allergies (National
Institutes of Health [NIH], 2015), anxiety disorder (Salim et al.,
2012), asthma (Murdoch and Lloyd, 2010), cardiovascular disease
(Mari et al., 2002; Ho et al., 2010; Schiffrin, 2013), depression
(Calabrese et al., 2014), diabetes mellitus (Pedicino et al.,
2013), eczema (National Institutes of Health [NIH], 2014), and
musculoskeletal complaints (Ji et al., 2002; Wang et al., 2011).
Finally, immune functioning is important in healthy birth weight
(Moffett et al., 2014), and is suspected to play a role in ADHD
(Segman et al., 2002; Budziszewska et al., 2010) and migraines
(Bruno et al., 2007).
Available evidence indicates that enhanced immune function
fulfills the second criterion for a central pathway.
Criterion #3: Subsuming Other Pathways
between Nature and Health
A nature–health pathway is more central if it subsumes other
pathways; the more other pathways it subsumes, the more central
its role. As Figure 2 shows, the current literature suggests
enhanced immune function can subsume as many as 18 out of
the 20 other possible pathways between nature and health.
Enhanced immune function is known to wholly or partially
subsume 11 other pathways. Each of the following is known
to enhance immune function adiponectin (Fantuzzi, 2013),
reduced air pollution (e.g., Nadeau et al., 2010), awe (Stellar
et al., 2015), normalized levels of blood glucose (as compared
to elevated levels, Geerlings and Hoepelman, 1999), reduced
obesity (de Heredia et al., 2012), physical activity (Shepherd
et al., 1991), phytoncides (Li et al., 2009), better sleep
(Besedovsky et al., 2012), social ties (Kiecolt-Glaser et al.,
2002; Robles and Kiecolt-Glaser, 2003), relaxation and stress
reduction (Abboud et al., 2012; Bhasin et al., 2013), and
reduced immediate and long-term traumatic stress due to
violence (e.g., Baum et al., 1993). Note that these pathways
may be partially or wholly subsumed by the enhanced immune
functioning pathway between nature and health; if a pathway
contributes to health via both the immune system and other
effects, it is partially subsumed by the immune function
For seven additional pathways, while there is no direct
evidence tying them to human immune function, there is
indirect evidence suggesting such a tie. DHEA (Hazeldine
et al., 2010), mycobacterium vaccae (Lowry et al., 2007), and
negative air ions (Yamada et al., 2006)areallknownto
improve immune function in mice. Vitality enhances resistance
to upper respiratory tract infections (see vigor findings in Cohen
et al., 2006), an effect mostly likely mediated via enhanced
immune functioning. Both visual (e.g., Brown et al., 2013)and
auditory (e.g., Alvarsson et al., 2010) nature stimuli are likely to
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Kuo Nature-health mechanisms
boost immune function by way of their demonstrated effects
on parasympathetic activity, and the subsequent effects of
parasympathetic activity on immune function (Kenney and
Ganta, 2014). And environmental biodiversity has been proposed
to help train and regulate the immune system, although the
findings here are correlational and mixed (e.g., Ruokolainen et al.,
Enhanced immune function fulfills the third criterion for a
central pathway.
This review reveals a multiplicity of mechanisms by which
contact with nature might promote health, as well as a promising
candidate for a central pathway. There may be other mechanisms,
such as other physiological effects, reduced accidents, and
healthier behaviors. There may also be other central contributors
to the nature-health link of those reviewed here, deep
relaxation, attention restoration and impulse control, sleep, and
social ties seem particularly worthy of attention. No doubt some
of the plausible pathways identified here will prove either not
to contribute substantially to natures impact on health, or to
contribute only under certain limited circumstances; here, the
roles of improved air quality, environmental biodiversity and
microbiota, and physical activity merit closer study.
These limitations notwithstanding, this review makes a
number of contributions to our understanding of nature and
health, to future investigation in this area, and to the creation
of healthy human habitats. The multiplicity of nature–health
pathways identified here lends credibility to the hypothesis that
nature actually promotes health, aswellasapotentialexplanation
for the startling size and scope of natures apparent impact.
With so many contributing pathways operating in concert, the
cumulative effect could be quite large even if many of the
individual pathways contribute only a small effect that is, the
effect of exposure to phytoncides plus exposure to mycobacteria
vaccae plus increased adiponectin plus stronger social ties plus
better sleep, etc., could indeed be quite large, and if some of the
pathways, such as enhanced immune function, contribute a large
effect, the combined effect would be larger still.
For future work in this area, the criteria here give researchers
interested in central mechanisms a means of using existing
literature to assess the centrality of a particular mechanism. In
addition the detailed reviews provided in the Supplementary
Materials may provide a useful starting point for researchers
interested in specific pathways or specific health outcomes of
Finally, the findings here can help guide the creation of
healthy human habitats. The existing literature speaks to the
value not only of “wild” nature but also everyday” nature
the views and green spaces where we live. That physical activity
is not consistently related to greener environments suggests
that our conceptualization of health-promoting greenspaces
should center at least as much on oases as on ball fields,
and on greenspaces for walking and quiet contemplation as
much as on recreation areas. The findings here suggest that
such oases should incorporate plants — especially trees, soil,
and water (preferably moving) and should be designed to
induce feelings of deep relaxation, awe, and vitality. Providing
these green oases, especially in areas where health risks are
high and landscaping is sparse, might be an inexpensive,
powerful public health intervention and address persisting health
I am grateful to the TKF Foundation for encouragement and
financial assistance in gathering some of the necessary literature
for this work through its Nature Sacred National Awards
program. This review is more clear, better structured, more
interesting, and more complete than it would have been without
the thoughtful intervention of Kirstin Wilcox, Rafter S. Ferguson,
Dexter Locke, Meghan Frankel, Natalia Maurer, and reviewers
Sumitava Mukherjee and Teresa Helen Horton: thank you!
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Conflict of Interest Statement: The author declares that the research was
conducted in the absence of any commercial or financial relationships that could
be construed as a potential conflict of interest.
Copyright © 2015 Kuo. This is an open-access article distributed under the terms
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Frontiers in Psychology | 8 August 2015 | Volume 6 | Article 1093
... The relevance of urban green space for enriched immune system's function in the relationship between health and nature [18]. Being in touch with and interacting with nature triggers positive immunological reactions, such as the production of anti-cancer proteins [19]. ...
... Green space may boost the aesthetic value of a building's property while decreasing noise levels inside and outside [6] [31]. Green space benefits buildings and human lifestyles [18]. ...
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The pandemic issue is frequently discussed in the news or mass media. In 2002, Ebola, SARS, and SARS-CoV-2 were highly infective viruses that caused a global pandemic, according to the pandemic chronology. Animals in the forest spread each of these viruses to people. Since the 1918 influenza pandemic, the unique human coronavirus COVID-19 has caused the fifth documented pandemic. In this era, there has been an increase in public awareness about urban green spaces. Many studies suggest that proper landscape planning and design with a sustainable mindset may provide a helpful and responsive environment for healthy urban improvement during pandemic crises. Thus, this study aims to look into the functions of urban green spaces for long-term environmental health, especially during pandemic crises. The research revealed that urban green spaces improve immune system performance, promote social capital and cohesiveness, reduce mortality, lengthen life expectancy, and potential adverse health impacts. The findings also emphasised various advantages of urban green spaces during pandemics, such as enhanced mental and physical well-being, less risk of disease transmission, and enhanced social cohesion. In summary, urban green space sustainability may support a healthy environment and lifestyle in metropolitan areas amid pandemic crises.
... Hal Efek peremajaan perhatian melalui pembelajaran berbasis alam pada orang dewasa telah banyak dibuktikan oleh peneltian sebelumnya, misalnya kelelahan secara mental dan meningkatkan konsentrasi (Kuo, et al., 2019;Li & Sullivan, 2016). Pertimbangan lainnya yaitu pembelajaran melalui alam dapat mendorong hubungan manusia dengan alam, mencegah stres, serta memiliki efek tambahan positif bagi kesehatan (Frumkin, et al., 2017;Kuo, 2015). ...
... In addition to physical activity and social contact, Kuo (2015) added that sleep is another behavioural factor linking nature and human health. To date, many studies have suggested that exposure to residential greenspace can increase sleep duration (Shin et al. 2020), and this may further positively impact health (e.g. ...
Plant-enriched environments, the most common terrestrial landscapes, are usually coded as “green space” in urban studies. To understand how these natural environments can benefit human health, many theories have been developed, such as the well-known Attention Restoration Theory. Nowadays, more theories are emerging with regard to various and complex health dimensions. In this context, we searched online databases (from 2000 to 2022) and conducted a narrative review aiming to introduce relevant theories concerning psychological (e.g. Perceptual Fluency Account and Conditioned Restoration Theory), physiological (e.g. volatile organic compounds and environmental microbiomes), and behavioural (e.g. physical activity and social contact) perspectives. We also slightly mentioned some limitations and directions to be considered when using these theories. These results may offer general readers insights into the value of nature exposure and also help relevant researchers with study design and result interpretation.
... These benefits of greenness exposure, collectively referred to as "ecosystem services" (Bratman et al., 2019), could directly contribute to human well-being. In addition, greenness could act as a catalyst to facilitate the changes in behaviors and lifestyles from sedentary behaviors to more outdoor physical activities and from socially isolated to active community engagement, both of which are more conducive to physical and mental health (Dadvand et al., 2016;Kuo, 2015). Markevych et al. (2017) and Marselle et al. (2021) summarize the above health effects of greenness through four pathways: reducing harm, restoring capacities, building capacities, and causing harm. ...
Human exposure to greenness is associated with COVID-19 prevalence and severity, but most relevant research has focused on the relationships between greenness and COVID-19 infection rates. In contrast, relatively little is known about the associations between greenness and COVID-19 hospitalizations and deaths, which are important for risk assessment, resource allocation, and intervention strategies. Moreover, it is unclear whether greenness could help reduce health inequities by offering more benefits to disadvantaged populations. Here, we estimated the associations between availability of greenness (expressed as population-density-weighted normalized difference vegetation index) and COVID-19 outcomes across the urban–rural continuum gradient in the United States using generalized additive models with a negative binomial distribution. We aggregated individual COVID-19 records at the county level, which includes 3,040 counties for COVID-19 case infection rates, 1,397 counties for case hospitalization rates, and 1,305 counties for case fatality rates. Our area-level ecological study suggests that although availability of greenness shows null relationships with COVID-19 case hospitalization and fatality rates, COVID-19 infection rate is statistically significant and negatively associated with more greenness availability. When performing stratified analyses by different sociodemographic groups, availability of greenness shows stronger negative associations for men than for women, and for adults than for the elderly. This indicates that greenness might have greater health benefits for the former than the latter, and thus has limited effects for ameliorating COVID-19 related inequity. The revealed greenness-COVID-19 links across different space, time and sociodemographic groups provide working hypotheses for the targeted design of nature-based interventions and greening policies to benefit human well-being and reduce health inequity. This has important implications for the post-pandemic recovery and future public health crises.
... Urban green spaces provide various cultural services such as recreation and restoration. Existing literature indicates that exposure to green spaces is associated with a range of human health benefits through mechanisms including the promotion of physical exercise (Kuo, 2015;Schipperijn et al., 2017), stress relief (Thompson, 2010;Zhao et al., 2018a), greater biodiversity (Haahtela, 2019), and the improvement of urban environments (Song et al., 2015). Previous research primarily addresses the healing effects of urban green spaces during the daytime (e.g. ...
This chapter engages with the burgeoning international phenomenon of therapeutic nature practices, such as ecotherapy, forest bathing, and forest therapy. This is informed by the author’s ethnographic research in European geographical and cultural contexts with much in common but also notable differences: Wales, Sweden, and Finland. In all of these fieldwork contexts the idea that ‘natural’ spaces were somewhere one could ‘get away’ to as an ‘escape’, as something ‘set apart’ or seen as ‘other’, was key to the therapeutic framing of the activities. This was both an escape from perceived pathological effects of society and an escape to a complex community of life represented by nature. Therefore in these fields nature is a community, but one without social roles and stratification, a communitas, as described by Victor Turner. In Turner’s understanding, communitas arises in a liminal state, an in-between state where the social system is dissolved within a ritual framework, enabling participants to transform, reconstitute themselves, and re-enter society in a new role. A lack of social roles and demands is still an absence, of course. However, in many practitioners’ accounts it is also clear that positive characteristics are attributed to earth beings. The presence of life and living beings is experienced as revitalising. A transformation can be argued to take place, but this is primarily within the individual, rather than outer cultural or societal change. Also of note was a mostly positive view of nature, with little consideration of the potential for threat or danger. The chapter concludes with a reflection on how therapeutic nature practices both reflect and resist contemporary Western culture.
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It has long been known that the forest, as a "feel-good space," has a positive effect on human well-being. In recent years, medical studies have also been conducted on this subject. However, there are only a few studies with a sufficient number of cases and valid statistics. The article describes the various health effects of forest visits on humans, such as physiological and psychological changes, although the mechanisms of action are often still unclear. The field of forest and health research is still in its infancy. A cooperation between the chairs "Forest and Environmental Policy" (TUM) and "Public Health and Health Services Research (IBE)" (LMU) will deal intensively with this topic in the coming years.
It is unclear how the COVID-19 pandemic will affect the design, use, and perception of public spaces in the future. The meaning and use of public spaces designed to bring individuals together is changing and transforming. This study seeks answers to the following questions: How will it change our relationship with public space? How long will we endure this change and transformation? Is the COVID-19 pandemic diverting our attention from climate change and sustainability? The aim of this chapter is to read these research questions and ideas about how the relationship of the COVID-19 pandemic with public space will change and transform through the social sustainability feature of public space. The study focused on the relationship between these 11 dimensions of social sustainability and public spaces. The dimensions determined in this framework are accessibility, security, comfort, readability, social cohesion, quality of life, sense of belonging, inclusiveness, social opportunities, public services, diversity.
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Human birthweight is subject to stabilizing selection. Large babies are at risk of obstetric complications such as obstructed labour, which endangers both mother and child. Small babies are also at risk with reduced survival. Fetal growth requires remodelling of maternal spiral arteries to provide an adequate maternal blood supply to the placenta. This arterial transformation is achieved by placental trophoblast cells, which invade into the uterine wall. Under-invasion is associated with fetal growth restriction; but if invasion is excessive large babies can result. A growing body of evidence suggests that this process is controlled by interactions between killer-cell immunoglobulin-like receptors (KIRs) expressed on maternal uterine natural killer cells (uNK) and their corresponding human leukocyte antigen-C (HLA-C) ligands on invading trophoblast. Mothers with the KIR AA genotype and a fetus with a paternal HLA-C2 allele tend to have small babies, because this combination inhibits cytokine secretion by uNK. Mothers with the activating KIR2DS1 gene and an HLA-C2 fetus are more likely to have large babies. When KIR2DS1 binds to HLA-C2 this increases secretion of cytokines that enhance trophoblast invasion. We conclude that specific combinations of the highly polymorphic gene systems, KIR and HLA-C, contribute to successful reproduction by maintaining birthweight between two extremes. © 2015 The Author(s) Published by the Royal Society. All rights reserved.
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Cytokines are key regulatory mediators involved in the host response to immunological challenges, but also play a critical role in the communication between the immune and the central nervous system. For this, their expression in both systems is under a tight regulatory control. However, pathological conditions may lead to an overproduction of pro-inflammatory cytokines that may have a detrimental impact on central nervous system. In particular, they may damage neuronal structure and function leading to deficits of neuroplasticity, the ability of nervous system to perceive, respond and adapt to external or internal stimuli. In search of the mechanisms by which pro-inflammatory cytokines may affect this crucial brain capability, we will discuss one of the most interesting hypotheses: the involvement of the neurotrophin brain-derived neurotrophic factor (BDNF), which represents one of the major mediators of neuroplasticity.
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Background Western lifestyle is associated with high prevalence of allergy, asthma and other chronic inflammatory disorders. To explain this association we tested the ‘biodiversity hypothesis’, which posits that reduced contact of children with environmental biodiversity, including environmental microbiota in natural habitats, has adverse consequences on the assembly of human commensal microbiota and its contribution to immune tolerance.Methods We analysed four study cohorts from Finland and Estonia (n = 1044) comprising children and adolescents aged 0.5–20 yrs. The prevalence of atopic sensitization was assessed by measuring serum IgE specific to inhalant allergens. We calculated the proportion of five land-use types—forest, agricultural land, built areas, wetlands, and water bodies—in the landscape around the homes using the CORINE2006 classification.ResultsThe cover of forest and agricultural land within 2–5 km from the home was inversely and significantly associated with atopic sensitization. This relationship was observed for children 6 years of age and older. Land-use pattern explained 20% of the variation in the relative abundance of Proteobacteria on the skin of healthy individuals, supporting the hypothesis of a strong environmental effect on the commensal microbiota.Conclusions The amount of green environment (forest and agricultural land) around home was inversely associated with the risk of atopic sensitization in children. The results indicate that early life exposure to green environments is especially important. The environmental effect may be mediated via the effect of environmental microbiota on the commensal microbiota influencing immunotolerance.This article is protected by copyright. All rights reserved.
Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder, where family data support substantial heritability. To date, association studies focussed mainly on genes regulating dopaminergic neurotransmission. Interleukin-1 (IL-1) activity in the brain has been implicated with differentiation of dopaminergic neurons and modulation of central monoaminergic reactivity. We investigated the role of interleukin-1 receptor antagonist (IL-1Ra) gene variable number tandem repeat (VNTR) polymorphism, in a sample of 86 children with DSM-IV ADHD and their parents. Transmission disequilibrium analysis showed increased transmission of the IL-1Ra 4-repeat allele (χ² = 4.07, P = 0.04) and decreased transmission of the 2-repeat allele (χ² = 4.59, P = 0.03) to affected children. The 4-repeat allele was associated with a significantly increased risk for ADHD (χ² = 4.46, df 1, P= 0.035, RR = 1.292, 95% CI 1.01-1.66). The IL-1Ra 2-repeat allele was associated with a significantly decreased risk for ADHD (χ² = 4.65, df 1, P = 0.03, RR = 0.763, 95% CI 0.59-0.98). If replicated, this finding may point to a role for brain cytokine activity in the etiopathogenesis of ADHD.
Natural killer (NK) cells are lymphocytes of the innate immune system that are critical in host defense and immune regulation. They are activated or inhibited through the ligation of germline-encoded receptors and are involved in mediating cytotoxicity, in producing cytokines and in providing co-stimulation to cells of the adaptive immune system. NK cells play important roles in viral infections, autoimmunity, pregnancy, cancer and bone marrow transplantation. This review highlights recent developments in the understanding of the role of human NK cells in health and disease. Published by Elsevier Inc.
THE CRISIS of violence in the United States has expanded to include more than the traditional emphasis on the victim and perpetrator. We would like to bring attention to a previously underrecognized group of victims in this public health epidemic: the children who witness the violence. These usually silent, indirect victims show no physical sign of harm and are commonly overlooked. In urban pediatric practices, clinicians increasingly are told that their young patients hear gunshots outside their homes, witness shootings on the playground, or have a family member (often an older sibling) involved with violence. Recent studies support this. One of every 10 children attending Boston (Mass) City Hospital pediatric primary care clinic witnessed a shooting or stabbing before the age of 6 years,1 half in the home, half on the streets. The average age of the children in this study was 2.7 years. A survey of elementary-school-aged children
Negative emotions are reliably associated with poorer health (e.g., Kiecolt-Glaser, McGuire, Robles, & Glaser, 2002), but only recently has research begun to acknowledge the important role of positive emotions for our physical health (Fredrickson, 2003). We examine the link between dispositional positive affect and one potential biological pathway between positive emotions and health-proinflammatory cytokines, specifically levels of interleukin-6 (IL-6). We hypothesized that greater trait positive affect would be associated with lower levels of IL-6 in a healthy sample. We found support for this hypothesis across two studies. We also explored the relationship between discrete positive emotions and IL-6 levels, finding that awe, measured in two different ways, was the strongest predictor of lower levels of proinflammatory cytokines. These effects held when controlling for relevant personality and health variables. This work suggests a potential biological pathway between positive emotions and health through proinflammatory cytokines. (PsycINFO Database Record (c) 2015 APA, all rights reserved).