Urban open space
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land-use planning Land use planning is the process of regulating the use of land by a central authority. Usually, this is done to promote more desirable social and environmental outcomes as well as a more efficient use of resources. More specifically, the goals ...
, urban green space is open-space areas reserved for
park A park is an area of natural, semi-natural or planted space set aside for human enjoyment and recreation or for the protection of wildlife or natural habitats. Urban parks are green spaces set aside for recreation inside towns and cities. ...
s and other "green spaces", including plant life, water features -also referred to as blue spaces- and other kinds of natural environment. Most urban open spaces are green spaces, but occasionally include other kinds of open areas. The landscape of urban open spaces can range from playing fields to highly maintained environments to relatively
natural landscape A natural landscape is the original landscape that exists before it is acted upon by human culture. The natural landscape and the cultural landscape are separate parts of the landscape. However, in the 21st century, landscapes that are totally ...
s. Generally considered open to the public, urban green spaces are sometimes privately owned, such as higher education campuses, neighborhood/community parks/gardens, and institutional or corporate grounds. Areas outside city boundaries, such as state and
national park A national park is a natural park in use for conservation purposes, created and protected by national governments. Often it is a reserve of natural, semi-natural, or developed land that a sovereign state declares or owns. Although individual ...
s as well as open space in the countryside, are not considered urban open space. Streets, piazzas, plazas and urban squares are not always defined as urban open space in land use planning. Urban green spaces have wide reaching positive impacts on the health of individuals and communities near the green space. Urban greening policies are important for revitalizing communities, reducing financial burdens of healthcare and increasing quality of life. Most policies focus on community benefits, and reducing negative effects of urban development, such as
surface runoff Surface runoff (also known as overland flow) is the flow of water occurring on the ground surface when excess rainwater, stormwater, meltwater, or other sources, can no longer sufficiently rapidly infiltrate in the soil. This can occur when t ...
and the
urban heat island An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparent ...
effect. Historically, access to green space has favored wealthier, and more privileged communities, thus recent focus in urban greening has increasingly focused on
environmental justice Environmental justice is a social movement to address the unfair exposure of poor and marginalized communities to harms from hazardous waste, resource extraction, and other land uses.Schlosberg, David. (2007) ''Defining Environmental Justi ...
concerns, and community engagement in the greening process. In particular, in cities with economic decline, such as the
Rust Belt The Rust Belt is a region of the United States that experienced industrial decline starting in the 1950s. The U.S. manufacturing sector as a percentage of the U.S. GDP peaked in 1953 and has been in decline since, impacting certain regions an ...
in the United States, urban greening has broad community revitalization impacts. Urban areas have greatly expanded and resulted in over half of the world's population to be located in urban locations. As the population continues to grow, this number is predicted to be at two-thirds of people living in urban areas by 2050.


Definitions and concepts

People living in cities and towns generally have weaker mental health in comparison to people living in less crowded areas. Urban green spaces are pieces of nature in the cities designed to try to solve the problem. Most research on the topic focus on urban green spaces. The WHO defined this as "all urban land covered by vegation of any kind". When doing research, some experts use "urban open space" to describe a broader range of open areas. One definition holds that, "As the counterpart of development, urban open space is a natural and cultural resource, synonymous with neither 'unused land' nor 'park and recreation areas." Another is "Open space is land and/or water area with its surface open to the sky, consciously acquired or publicly regulated to serve conservation and urban shaping function in addition to providing recreational opportunities." In almost all instances, the space referred to by the term is, in fact, green space, focused on natural areas. These spaces are part of "public space" broadly construed, which include meeting or gathering places that exist outside the home and workplace that are generally accessible by members of the public, and which foster resident interaction and opportunities for contact and proximity. This definition implies a higher level of community interaction and places a focus on public involvement rather than public ownership or stewardship.


Benefits

The benefits that urban open space provides to citizens can be broken into four basic forms; recreation, ecology, aesthetic value, and positive health impacts. Psychological benefits gained by visitors to urban green spaces increased with their biodiversity, indicating that 'green' alone is not sufficient; the quality of that green is important as well.


Recreational

Urban open space is often appreciated for the recreational opportunities it provides.
Recreation Recreation is an activity of leisure, leisure being discretionary time. The "need to do something for recreation" is an essential element of human biology and psychology. Recreational activities are often done for enjoyment, amusement, or plea ...
in urban open space may include active recreation (such as organized sports and individual exercise) or passive recreation, which may simply entail being in the open space. Research shows that when open spaces are attractive and accessible, people are more likely to engage in physical activity. Time spent in an urban open space for recreation offers a reprieve from the urban environment and a break from
over-stimulation Stimulation is the encouragement of development or the cause of activity generally. For example, "The press provides stimulation of political discourse." An interesting or fun activity can be described as "stimulating", regardless of its physic ...
. Studies done on physically active adults middle aged and older show there are amplified benefits when the physical activities are coupled with green space environments. Such coupling leads to decreased levels of stress, lowers the risk for depression as well as increase the frequency of participation in exercise. Casual group walks in a green environment (nature walks) increase one's positive attitude and lower stress levels as well as risk of depression.


Ecological

The conservation of nature in an urban environment has direct impact on people for another reason as well. A Toronto civic affairs bulletin entitled ''Urban Open Space: Luxury or Necessity'' makes the claim that "popular awareness of the balance of nature, of natural processes and of man's place in and effect on nature – i.e., " ecological awareness" – is important. As humans live more and more in man-made surroundings – i.e., cities – he risks harming himself by building and acting in ignorance of natural processes." Beyond this man-nature benefit, urban open spaces also serve as islands of nature, promoting
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic ('' genetic variability''), species ('' species diversity''), and ecosystem ('' ecosystem diversity'') ...
and providing a home for natural species in environments that are otherwise uninhabitable due to city development. By having the opportunity to be within an urban green space, people gain a higher appreciation for the nature around them. As
Bill McKibben William Ernest McKibben (born December 8, 1960)"Bill Ernest McKibben." ''Environmental Encyclopedia''. Edited by Deirdre S. Blanchfield. Farmington Hills, Mich.: Gale, 2009. Retrieved via ''Biography in Context'' database, December 31, 2017. is a ...
mentions in his book ''The End of Nature'', people will only truly understand nature if they are immersed within it. He follows in
Henry David Thoreau Henry David Thoreau (July 12, 1817May 6, 1862) was an American naturalist, essayist, poet, and philosopher. A leading transcendentalist, he is best known for his book ''Walden'', a reflection upon simple living in natural surroundings, and h ...
's footsteps when he isolated himself in the Adirondack Mountains in order to get away from society and the overwhelming ideals it carries. Even there he writes how society and human impact follows him as he sees airplanes buzzing overhead or hears the roar of motorboats in the distance.


Aesthetic

The
aesthetic value Aesthetics, or esthetics, is a branch of philosophy that deals with the nature of beauty and taste, as well as the philosophy of art (its own area of philosophy that comes out of aesthetics). It examines aesthetic values, often expressed thr ...
of urban open spaces is self-evident. People enjoy viewing nature, especially when it is otherwise extensively deprived, as is the case in urban environments. Therefore, open space offers the value of "substituting gray infrastructure."Eysenbach, Mary. "Park System Function and Services." From Recreation to Re-creation. American Planning Association, 2008. One researcher states how attractive neighborhoods contribute to positive attitudes and social norms that encourage walking and community values. Properties near urban open space tend to have a higher value. One study was able to demonstrate that, "a pleasant view can lead to a considerable increase in house price, particularly if the house overlooks water (8–10%) or open space (6–12%)." Certain benefits may be derived from exposure to virtual versions of the natural environment, too. For example, people who were shown pictures of scenic, natural environments had increased brain activity in the region associated with recalling happy memories, compared to people that were shown pictures of urban landscapes.


Impact on health

The
World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level o ...
considers urban green spaces as important to human health. These areas have a positive impact on mental and physical health. Urban open spaces often include trees or other shrubbery that contribute to moderating temperatures and decreasing
air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different type ...
. Perceived general health is higher in populations with a higher percentage of green space in their environments. Urban open space access has also been directly related to reductions in the prevalence and severity of chronic diseases resulting from sedentary lifestyles, to improvements in mental well-being, and to reductions in population-wide health impacts from climate change.


Reductions in Chronic Disease Rates

Improved access to green space is associated with reductions in
cardiovascular disease Cardiovascular disease (CVD) is a class of diseases that involve the heart or blood vessels. CVD includes coronary artery diseases (CAD) such as angina and myocardial infarction (commonly known as a heart attack). Other CVDs include stroke, hea ...
symptoms, improved rates of
physical activity Physical activity is defined as any voluntary bodily movement produced by skeletal muscles that requires energy expenditure.Global Recommendations on Physical Activity for Health, 2009. World Health Organization. Geneva, Switzerland. Accessed 13/ ...
, lower incidence of
obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...
, and improved respiratory health. Lower rates of cardiovascular biomarkers are associated with access to green space, showing a reduction in cardiovascular disease risk in populations living within 1 km of green space. Not only does access to urban green space reduce risk of cardiovascular disease, but increased access has been shown to improve recovery from major adverse cardiovascular events and lower all-cause mortality. Relationships have been found between increased access to green space, improved rates of physical activity, and reduced BMI. The percentage of sedentary and moderately active persons making use of an urban park increased when access to the park was improved.


Reductions in Mental Illness rates / Improved Social Cohesion

Mental illness A mental disorder, also referred to as a mental illness or psychiatric disorder, is a behavioral or mental pattern that causes significant distress or impairment of personal functioning. Such features may be persistent, relapsing and remitt ...
has been a major taboo and concern in the current fast paced world in which time to relax is undervalued.  Globally, mental illness is linked to eight million deaths each year. In
urban area An urban area, built-up area or urban agglomeration is a human settlement with a high population density and infrastructure of built environment. Urban areas are created through urbanization and are categorized by urban morphology as cities ...
s, limited access to green space and poor quality of green spaces available may contribute to poor mental health outcomes. The distance an individual lives from a green space or park and the proportion of land designated as open space/parks has been shown to be inversely related to anxiety/
mood disorder A mood disorder, also known as an affective disorder, is any of a group of conditions of mental and behavioral disorder where a disturbance in the person's mood is the main underlying feature. The classification is in the '' Diagnostic and St ...
treatment counts in the community. Improved mental health may therefore be related to both measures - to distance from open space and proportion of open space within a neighborhood. Even when physical activity rates are not shown to increase with greater access to green space, greater access to green space has been shown to decrease stress and improve social cohesion.


Effects of Urban Green Space on Respiratory Health

Adequate urban green space access can be associated with better respiratory health outcomes, as long as green space areas meet certain requirements.  A new study showed that mortality due to pneumonia and chronic lower respiratory diseases could be reduced by minimizing fragmentation of green spaces and increasing the largest patch percentage of green space. Vegetation type (trees, shrubs and herbaceous layers) and lack of management (pruning, irrigation and fertilization) has been shown to affect a higher capacity to provide the ecosystem services of
air purification An air purifier or air cleaner is a device which removes contaminants from the air in a room to improve indoor air quality. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating ...
and climate regulation within green urban spaces. The types of plants and shrubs are important because areas with large tree canopies can actually contribute to asthma and allergic sensitization.


Mechanism of Urban Open Space Health Effects

Access to urban open space encourages physical activity and reduces ambient air pollution, heat, traffic noise and
emissions Emission may refer to: Chemical products * Emission of air pollutants, notably: **Flue gas, gas exiting to the atmosphere via a flue ** Exhaust gas, flue gas generated by fuel combustion ** Emission of greenhouse gases, which absorb and emit radi ...
. All are factors which contribute to the risks of chronic disease and mental illness. Individuals and families who lived closer to ‘formal’ parks or open space were more likely to achieve the recommended amounts of physical activity. Better respiratory health is associated with cleaner air quality. Cleaner air quality affects rates of chronic disease in populations exposed. “High concentrations of ambient particles can trigger the onset of acute myocardial infarction and increase hospitalization for cardiovascular disease”. Besides an association with lower BMI/obesity rates, this physical activity can increase lung function and be a protective factor against respiratory disease. Exposure to nature improve the
Immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splinte ...
. The contact of the human body with
soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...
, turf, forest floor, expose it to many microorganisms what boost the immune system.


Impacts on mental health

The advocacy for mental health is becoming increasingly rampant, given the psychiatric illnesses that contribute significantly to morbidity and mortality in the United States. Health disparities existing within and amongst communities make this issue of paramount importance. The correlation between psychological distress and socioeconomic status (SES) has previously been examined. Sugiyama demonstrates that psychological distress is positively correlated with lower SES. A contributing factor to this socioeconomic disparity is the higher amounts of green space among residents with higher SES. Access to and active utilization of urban green space results in decreased rates of anxiety and depression, which are among the most common mental health illnesses. The positive association between mental health and green space was also supported by Van den Berg. The positive influence of urban green space on a community's perceived sense of mental wellness is achieved through uplifted moods, decreased stress levels, relaxation, recuperation, and increased human contact, which in itself promotes mental well-being. Given the burden of mental illness in the United States, it is important to examine the impact of urban green space on mental health and utilize this information to promote mental well-being across communities. Modern research evidence demonstrates urban green space has positive impacts on population level mental health. Evidence shows that designated green space in urban areas facilitates social interaction, fosters well-being, increases opportunities for exercise, and contributes to improvement in common mental health problems such as anxiety, depression, and stress. One randomized trial studied two groups: one composed of residents living in a neighborhood that had a greening intervention and one that did not. Among the participants who now live in a green neighborhood, those feeling depressed decreased by 41.5% and self-reported poor mental health decreased by 62.8%. Another study indicates that "the difference in depressive symptoms between an individual living in an environment with no tree canopy and an environment with tree canopy is larger than the difference in symptoms associated between individuals who are uninsured compared with individuals with private insurance". Incorporating green space into urban design is an impactful, equitable, affordable, and accessible way to decrease the burden of mental health. Further research on urban open spaces have recently found a positive link associating a mental health and well-being with increased access to green spaces in urban areas. The RESIDE Project, for example, has found a dose-response effect where the total area of public green spaces is associated with a greater overall wellbeing. Based on the study participants' survey responses, urban neighborhoods with more access to green spaces are more likely to report increased optimism, perception of usefulness, confidence, social interaction, and interest in new activities. Additionally, individuals living in neighborhoods within walking distance of parks have more opportunities to participate in recreational activities which is also associated with positive health outcomes. Another study published in the Journal of Epidemiology compared the effect of green spaces on 2,169 pairs of twins. After adjusting for genetic confounders and childhood environments, researchers found significant association between green spaces and decreased depression. Both examples of green spaces in urban areas illustrate how individual's environment can affect mental health and highlight the importance of access to green spaces. Furthermore, there are several strategies that policymakers have pursued in order to increase the amount of green space in urban areas. Two are explored here: a case study in Toronto's redevelopment of Brownfield sites, and a broad analysis of city-wide planning strategies.


Impacts on high temperatures

Urban areas tend to have higher temperatures than their surrounding undeveloped areas because of
Urban Heat Island An urban heat island (UHI) is an urban or metropolitan area that is significantly warmer than its surrounding rural areas due to human activities. The temperature difference is usually larger at night than during the day, and is most apparent ...
s, UHIs. Urban heat islands are areas with man-made infrastructure that contribute to the increased temperatures. The average temperature during the day in cities can be 18-27 degrees Fahrenheit higher than in the surrounding rural regions. This is an example of one type of UHI, surface heat islands. Surface heat islands encompass the area from the ground to the top of the tree-line. It is usually higher during the day when direct sunlight reaches urban structures (often with darker materials than natural areas) including the main contributor, pavement. The other type of UHI, atmospheric heat islands, are from above the tree-line to the level in the atmosphere where the urban area no longer has an effect. This type of heat island has increased heat at night due to the release of heat from infrastructure that built up throughout the day. Green spaces within urban areas can help reduce these increased temperatures through shading and evapotranspiration. Shading comes from the taller plants, such as trees, planted in green spaces that can contribute to lowering the surface heat island effect. The shade provides protection from the sun for vulnerable populations, such as children, during periods of increased temperature, during the summer months or during a heat wave. Tree cover prevents some solar radiation from reaching the ground with its leaves and branches. This reduces the effect of surface urban heat islands. Open spaces that include any type of vegetation help offset the high temperatures through the natural process of evapotranspiration. Evapotranspiration releases water into the air therefore dissipating heat. There are many elements of an urban open space that can contribute to the mitigation of urban heat islands including the type of open space (park or nature reserve), type of plant species, and the density of vegetation. Green spaces contribute to the reduction of local heat, decreasing the overall effect of UHIs. The larger the distribution of green spaces, the bigger the area of heat reduction. Green spaces that are clustered together will have an additive heat reduction resulting in a greater decrease in temperature in the local area compared to surrounding areas.


Impacts on air quality

Human activity has increased
air pollution Air pollution is the contamination of air due to the presence of substances in the atmosphere that are harmful to the health of humans and other living beings, or cause damage to the climate or to materials. There are many different type ...
in the earth's atmosphere and trees play an essential role in removing human-made pollutants from the air, aka particulate matter (PM). Trees produce oxygen and absorb CO2. In urban green spaces, trees filter out man-made pollutants. Air quality data collected on cities with and without urban green space has shown that areas with an abundance of trees have considerably less air pollutants, i.e. O3, PM10, NO2, SO2, and CO. As air pollutants accumulate in the atmosphere, vulnerable populations, such as children, may suffer from increased incidences of respiratory disease. Particulate matter or particle pollution with a diameter of 10 microns (PM10) or 2.5 microns (PM2.5) is associated with heart diseases and respiratory diseases including lung cancer. Globally, particulate matter has increased over 28% in indoor air and 35% in outdoor air. Children spend most of their time at school, around 10 hours daily, and the indoor and outdoor air has a large impact on their health. Schools located in urban areas have higher particulate matter than schools in rural areas. Compared with children in schools located in rural areas, children who attend schools located in industrial areas and urban cities have higher levels of urinary PAHs ( polycyclic aromatic hydrocarbons) metabolites, which is linked to air pollution. There are two different ways that green spaces can reduce the pollution of particulate matter including preventing distribution of particulate from pollutants or by reducing the particulate matter from traveling to other places. There is a disagreement about the association of living near green spaces or having high exposure to greenness and illness such as allergies, rhinitis, and eye and nose symptoms. Higher exposure to tree canopy and pollen was associated with a high risk of prevalence rhinitis, allergic sensitization, wheezing, and asthma among children 7 years-old. More studies are needed to explain the effect of urban green spaces on children relating to air quality. These studies should take into consideration the interconnectedness of tree species, geographic areas, temperature, and other pollutant-like traffic.


Case study: redevelopment of brownfield sites

Brownfield In urban planning, brownfield land is any previously developed land that is not currently in use. It may be potentially contaminated, but this is not required for the area to be considered brownfield. The term is also used to describe land pre ...
sites are defined as "abandoned, idled, or under-used industrial and commercial facilities where expansion or redevelopment is complicated by real or perceived
environmental contamination Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
." The
City of Toronto Toronto ( ; or ) is the capital city of the Canadian province of Ontario. With a recorded population of 2,794,356 in 2021, it is the most populous city in Canada and the fourth most populous city in North America. The city is the ancho ...
undertook an extensive redevelopment of Brownfield sites into green spaces starting in the 1950s. The first step was motivation. In 1954, Hurricane Hazel hit the city and caused considerable damage. The city subsequently obtained "flood lands" as a buffer to protect against future hurricanes. Later, there was an impetus to convert contaminated brownfields into greenspace for the perceived benefits, the top reasons being the creation of ecological habitats and to provide recreational opportunities. After establishing the motivation, the second step was to conduct a survey of all the Brownfield sites. Although the City of Toronto was responsible for the management of Brownfield sites, they had limited resources to do so. They began by taking an inventory of all the land that could be considered Brownfields. By contrast, the greenspace is much more actively managed by both the City of Toronto and the Toronto Region Conservation Authority. Over 12% of the urban land in Toronto is classified as green space. The third step involved holding meetings with both public and private stakeholders. Including the local neighborhood in the decision making process was seen as key to securing the cooperation of the public. Because there was little perceived economic gain by private stakeholders, the redevelopment project was largely carried out by the public sector. The fourth step was delegation. A single department was put in charge of the project, which in this case was the municipal government's Parks Department (the government absorbed 90–100% of the implementation costs). It was expected that implementation would take several years after delegation – in this case, redevelopment took between 3–5 years for each individual site. The fifth step was collaboration with other government agencies. Government agencies that shared land in common with the municipal government, such as flood plains and waterfronts, negotiated with each other in order to ensure the concurrency of the goals between the various agencies and Toronto's redevelopment efforts. A sixth step involved the acquisition of private land, which was either donated or purchased by the city. It is important to recognize that a substantial amount of Brownfield sites may reside on private land, and that a city must legally acquire it in order to implement redevelopment. The seventh step assessed each site individually. Because the sites were contaminated to different degrees, specific cleanup criteria were determined for each site, with various remediation strategies for each. The most common method was to cap (bury) the contaminants in situ. None of this could have happened unless there was a prerequisite zeroth step: creating an atmosphere of high trust. The City of Toronto was trusted by its citizens, and that trust enabled the city to redevelop Brownfield sites. The public sector was expected to do its job and to prevent people using the new green space from being exposed to contaminants. CITY–WIDE GREEN SPACE PLANNING: The concept that ecosystems provide services that improve quality of life for city residents is becoming more and more recognized. With that recognition, a shift in understanding green space from being an aesthetic contribution to city beautification to an essential part of the urban center is occurring. However, city planners are increasingly faced with densification and population increase in urban centers. This places stress on existing green spaces and can inhibit the creation of new green spaces. Notably, per capita GDP was found to be positively correlated with the amount of green space coverage. This suggests that economic systems that facilitate the accumulation of wealth can provision a city with increased green space. This must be balanced with the finding that greening efforts in low income sections of a city can cause rents to rise and make housing less affordable there. Additionally, it was found that European cities that distributed the management of green space among several governmental agencies were less successful in green space planning compared to cities with only one agency responsible. Lack of public awareness about the value of urban green space can also lead to less stakeholder contribution to green space planning. This suggests that public education can lead the population to more fully participate as informed stakeholders to a much greater extent. Additionally, improvement in the quality of green space can be pursued when no additional green space can be added. Furthermore, the concept of "green fingers," can be implemented in city-wide planning in order to optimize green space geometry. "Green fingers" is a strategy that connects urban green space from the city center to the periphery, thereby linking the rural to the urban in a continuous fashion and enabling better resident access. Developing
green roof A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and draina ...
s, gardens, and facades may be appropriate strategies for private land and buildings, but these cannot fulfill the functions of a public green space. Nevertheless they provide valuable contributions to resident quality of life, and can be supported by various tax beak incentives. Finally, heritage green space sites can be protected by various laws and regulations. All in all, the implementation of urban green space strategies must consider the entire urban region in question in order to achieve the overarching goal to provide urban residents with a higher
quality of life Quality of life (QOL) is defined by the World Health Organization as "an individual's perception of their position in life in the context of the culture and value systems in which they live and in relation to their goals, expectations, standards ...
. While the current research on the impacts of green space of mental health appears broad, the future of green space is still of utmost importance. Many US cities have unique plans to address this issue, while others are already experiencing the effects of reduced greenspace.
Denver Denver () is a consolidated city and county, the capital, and most populous city of the U.S. state of Colorado. Its population was 715,522 at the 2020 census, a 19.22% increase since 2010. It is the 19th-most populous city in the Unit ...
, for example, once boasted a meager 20% of the city having been paved or built-over in the mid-1970s. However, this number could reach closer to 70% by 2040 due to an explosion of the city's population. The hyper-functionality of modern-day cities must also be able to exist in a way that portrays beauty in the infrastructure itself. One proposed solution to this involves shifting grey infrastructure made of
concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wid ...
towards green infrastructure that looks less industrial and more like an ecosystem. This proposal, brought forth by the California Center for Sustainable Communities, accompanies another idea that cities should assess green space initiatives based on their cultural and natural assets. For example, Cairns, Australia embraces "tropical urbanism" as the basis for its green space landscape throughout the city, while
Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...
describes its future parks as "mountain urbanism". One study found that there was not a significant association between the amount of green space in residents' local areas and mental wellbeing, suggesting that the quality of green space may be what matters most. Ultimately, improving the quality of green space is a main concern for cities of the future and acting on a city's cultural and natural strengths is the best method to achieve this.


For children and adolescents


Impacts on physical health

The adolescent years are extremely important for children due to it being a time of growth, development, and instillation of habits. When children are given the opportunity to be active, they typically take advantage of it. Children with a greater access to parks and recreational facilities through urban green space have been found to be more active than children who lack access. The access to green spaces has shown an association with recreational walking, increased physical activity, and reduced sedentary time in all ages. In coordination, it has been seen that higher residential green space is associated with lower BMI scores. If children are given the opportunity to be active and maintain a healthy BMI in their adolescent years, they are less likely to be obese as adults.


Impacts on mental health

Children exposed to urban green spaces have the opportunity to expend energy by interacting with their environment and other people through exercise. One study has shown that without access to urban green spaces, some children have problems with hyperactivity, peer interactions, and good conduct. The important interactions with nature, animals, and peers have been positively influential in child development and reduction in behavioral issues such as Attention Deficit Hyperactivity Disorder (ADHD). Urban green spaces allow children to expel their extra energy and improve their ability to focus when needed both at school and home. In addition to behavioral problems, and likely connected, access to urban green space has been proven to be helpful for cognitive development. With urban green space giving children the opportunity to get outside and expend energy, children are more focused in school and have a better working memory and reduced inattentiveness. Another facet of urban green space improving mental health is giving children access to a community. Recreational activities and playing at the park gives children opportunities to interact with other children and develop a social circle and social skills in general. Children with a good social network feel socially included, promoting more confidence and well-being in their everyday lives. Overall, the bonding experiences that result from urban green spaces tie in with a child's cognitive and social development. A 2020 study suggested that increased access to urban green space increased the IQ of children by 2.6 points. (around 3% on average) A 2021 study found that higher exposure to
woodland A woodland () is, in the broad sense, land covered with trees, or in a narrow sense, synonymous with wood (or in the U.S., the '' plurale tantum'' woods), a low-density forest forming open habitats with plenty of sunlight and limited shade (see ...
urban green spaces or urban forest but not grassland is associated with improved cognitive development and risks of mental problems for urban adolescents.


History


Ancient Rome

The term "rus in urbe" meaning "country in the city" was used in Rome around the first century C.E.
Urban planning Urban planning, also known as town planning, city planning, regional planning, or rural planning, is a technical and political process that is focused on the development and design of land use and the built environment, including air, water, ...
in Rome valued the natural landscape and took account for environmental factors. It was thought that by building a city with regard to the local countryside, the people living there would be healthier and happier. English landscapes would later take inspiration from Roman urban planning concepts in their own open spaces.


London

London London is the capital and List of urban areas in the United Kingdom, largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary dow ...
has a long history of urban open space, which has significantly influenced development of modern parks, and is still among the greenest capital cities in the world. The basis for many urban open spaces seen today across Europe and the West began its process of development in London in the 17th and 18th centuries. What would eventually become urban open green space began as paved public plazas. Though they were intended to be open to the public, these spaces began to be re-designated as private parks around the late eighteenth century. It was during this period that the areas became pockets of green in the urban environment, commonly modelled after the natural wild of the countryside. The first parks to reverse the trend of privatization and again be opened to the public were England's
royal parks The Royal Parks of London are lands that were originally used for the recreation, mostly hunting, of the royal family. They are part of the hereditary possessions of The Crown, now managed by The Royal Parks Limited, a charity which manages ...
in the nineteenth century. This was done in response to the extensive and unexpected population movement from the country into cities. As a result, "the need for open space was socially and politically pressing… The problems, to which the provision of parks was expected to offer some relief, were easy to describe: overcrowding, poverty, squalor, ill-health, lack of morals and morale, and so on". Such sentiments again received significant popular support during the "
City Beautiful The City Beautiful Movement was a reform philosophy of North American architecture and urban planning that flourished during the 1890s and 1900s with the intent of introducing beautification and monumental grandeur in cities. It was a part of the ...
" movement in America during the 1890s and 1900s. Both trends focused on providing the public an opportunity to receive all of the perceived health and lifestyle benefits of having access to open space within urban environments.


Current trends

Segmentation of urban open spaces was particularly prominent in America during the twentieth century. Since the late 1800s romantic park systems, open space designers have been concerned with guiding, containing or separating urban growth, distributing recreation, and/or producing scenic amenity, mostly within the framework of geometric abstractions." Such segmentation was especially prominent in the 1990s, when urban open spaces took a path similar to that of parks, following the modernization trend of segmentation and specialization of areas.Young, Terence. "Modern Urban Parks." Geographical Review 1995. Pp 535–551 As modernity stressed "increased efficiency, quantifiablity, predictability, and control… In concert with the additional social divisions", open spaces grew more specific in purpose. Perhaps this increase in division of
social class A social class is a grouping of people into a set of hierarchical social categories, the most common being the upper, middle and lower classes. Membership in a social class can for example be dependent on education, wealth, occupation, inc ...
es' use of open space, demonstrated by the segmentation of the spaces, displays a situation similar to the privatization of London parks in the eighteenth century, which displayed a desire to make classes more distinct. Today, places like
Scandinavia Scandinavia; Sámi languages: /. ( ) is a subregion in Northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. In English usage, ''Scandinavia'' most commonly refers to Denmark, Norway, and S ...
, which do not have a significant history of outdoor recreation and gathering places, are seeing a proliferation of urban open spaces and adopting a lifestyle supported by the extra urban breathing room. An example of this can be seen in
Copenhagen Copenhagen ( or .; da, København ) is the capital and most populous city of Denmark, with a proper population of around 815.000 in the last quarter of 2022; and some 1.370,000 in the urban area; and the wider Copenhagen metropolitan a ...
where an area closed to car traffic in 1962 developed, in just a few decades, a culture of public political gatherings and outdoor cafes emerged. Not only is appreciation for and use of urban open spaces flourishing in locations that historically lacked such traditions, the number of urban open spaces is increasing rapidly as well. Non-sustainable gardening, including
mowing A mower is a person or machine that cuts (mows) grass or other plants that grow on the ground. Usually mowing is distinguished from reaping, which uses similar implements, but is the traditional term for harvesting grain crops, e.g. with reape ...
, use of chemical fertilisers,
herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page f ...
s and
pesticide Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and ...
s harm green spaces. Alumai, Alfred. "Urban Lawn Management: Addressing the Entomological, Agronomic, Economic, and Social Drivers." PhD., Ohio State University, 2008. Contrarywise, one of the conditions for good urban open space is sustainable gardening.


Urban blue spaces

At the beginning of the 21st century studies shows that living near water considerably improve physical and mental health, increase life longevity.


Inequalities

Green space access is related to health inequality for minority populations.  Neighborhoods with higher percentages of minority residents often have lower access to open space and parks as the result of past red-lining policies and current inequities in funding priorities. Urban open space is under strong pressure. Due to increasing
urbanization Urbanization (or urbanisation) refers to the population shift from rural to urban areas, the corresponding decrease in the proportion of people living in rural areas, and the ways in which societies adapt to this change. It is predominantly th ...
, combined with a spatial planning policy of densification, more people face the prospect of living in less green residential environments, especially people from low economic strata. This may cause environmental inequality with regard to the distribution of (access) to public green space. The parks that do exist in minority neighborhoods are often small (with lower acreage per person than parks in majority ethnicity neighborhoods), not well maintained, unsafe, or are otherwise ill-suited for community needs. A large epidemiological study. concluded that wealthier individuals were generally healthier than individuals with a lower income, explained by the pattern that wealthier individuals reside in areas more concentrated with green space. Urban open spaces in higher socioeconomic neighborhoods were also more likely to have trees that provided shade, a water feature (e.g. pond, lake and creek), walking and cycling paths, lighting, signage regarding dog access and signage restricting other activities as well. This difference in access has been proven, however, further study is needed to evaluate the exact health impacts. A study conducted in Australia provided insight into how there is a correlation between community development/community safety and natural open space within the community. Open areas allow community members to engage in highly social activities and facilitate the expansion of social networks and friendship development. As people become more social they decrease the perceptions of fear and mistrust allowing a sense of community bondage. Distant or lack of adequate green space, therefore, may contribute to higher rates of inactivity and greater health effects among minority populations.


Green gentrification


See also

* Open space reserve *
Green belt A green belt is a policy and land-use zone designation used in land-use planning to retain areas of largely undeveloped, wild, or agricultural land surrounding or neighboring urban areas. Similar concepts are greenways or green wedges, which h ...
* Greenway (landscape) *
Park A park is an area of natural, semi-natural or planted space set aside for human enjoyment and recreation or for the protection of wildlife or natural habitats. Urban parks are green spaces set aside for recreation inside towns and cities. ...
* Blue space * Principles of Intelligent Urbanism * Sustainable city * Urban forest *
Urban vitality Urban vitality is the quality of those spaces in cities that are capable of attracting heterogeneous people for different types of activities throughout varied time schedules. The areas of the city with high vitality are perceived as alive, live ...
* Village green * Greening


References


Further reading

* {{cite journal , last1 = McDonald , first1 = R. I. , last2 = Forman , first2 = R. T. T. , last3 = Kareiva , first3 = P. , year = 2010 , title = Open Space Loss and Land Inequality in United States' Cities, 1990–2000 , journal = PLoS ONE , volume = 5 , issue = 3, page = e9509 , doi = 10.1371/journal.pone.0009509 , pmid=20209082 , pmc=2831069, bibcode = 2010PLoSO...5.9509M , doi-access = free * Urban planning Open space Greenways Urban Protected areas Zoning