The degradation of natural environments inevitably affects human health in a negative way. According to World Health Organization (2012); environmental hazards are responsible for as much as a quarter of the total burden of disease world-wide, and more than one-third of the burden among children. The relationship between environment, particularly urban environments and human health is rather complex. There are too many environmental factors that influence human health. People are more likely to be exposed to pollution and infectious diseases in cities compared to natural environments. Besides, human behavior trends in urban environments facilitate microbial traffic (McMichael, 2000) and globalization expands the spread of epidemic diseases, mainly through global transportation of humans and goods. Moreover the changes in urban lifestyles lead to some serious health problems which decrease life quality. For instance, passive lifestyles of urbanized communities (i. e. low physical activity) are strongly linked to obesity which has become a major health problem throughout the world. Clinical studies have shown that there are many other serious health problems associated with obesity, such as diabetes (Mokdad et al., 2003), coronary heart disease (Flint et al., 2010), Alzheimer’s disease (Profenno et al., 2010), reduced fertility (Brannian, 2011), depression (Luppino et al.2010), osteoporosis (Paula & Rosen, 2010) and cancer (Freedland et al., 2009). Likewise, stress, which is an inevitable outcome of fast paced urban lifestyles, is found to have an impact upon the immune, circulatory, and nervous systems (Esch et al., 2003). Moreover, urban citizens have less contact opportunities with nature which is also linked to health and well being.
Parks and gardens are where urban citizens can contact with nature in their daily life. Health benefits of being in contact with natural environments have been known for centuries. In his writings the Roman senator Pliny the Younger described the mental and physical therapeutic effects of exercising and spending time in his villa gardens (Bowe, 2004; Ward Thompson, 2005). In Europe, during the medieval ages, the cloister gardens of the monasteries were used as healing gardens where patients were treated, exercised and relaxed (Ulrich, 2002; Ward Thompson, 2005). However an urban environment contains too many stimuli which attract directed attention. According to Kaplan’s Attention Restoration Theory (ART) (1995), intense directed attention causes mental fatigue and natural environments, where involuntary attention is attracted, help to recover from psychological fatigue and allow directed attention mechanisms to rest (Berman et al., 2008). Even viewing natural environments is suggested to have positive impacts on health. Kaplan (2001) points out that nature views from windows influences well being and residential satisfaction (Oguz et al., 2010). Similarly, Ulrich (2002) suggested that viewing nature or garden landscapes can reduce stress and improve effects of clinical treatments in hospitals. Grahn and Stigsdotter’s (2003) research also supports the idea that people, who spend more time in outdoor environments, are less affected by stress.
In the last century urban parks were referred as being "lungs of the city", which emphasizes their physical health benefits for urban citizens. As mentioned previously, urban vegetation cover provides a cleaner environment. Besides urban open and green spaces offer citizens’ environments to exercise. The positive effects of physical activity on human health are well known. The regular physical activity is associated with reduced rates of coronary heart disease, diabetes, hypertension, osteoporosis, colon cancer and depression (Powell & Prat, 1996). Wolch et al. (2011) found that body mass index (BMI) in children with better access to urban parks is less likely to show a significant increase. In their study, Maas et al. (2006) investigated the relationship between the amount of green space in living environments and perceived general health. They found that the amount of green space has a positive effect on health although the causes remain unknown. They also suggested that green spaces should be given more importance in spatial planning policies. However, according to Lee and Maheswaran (2010) there is weak evidence between green space and both physical and mental health, instead factors such as quality and accessibility influence the use of green spaces for physical activity purposes. On the other hand Takano et al. (2002) concluded that longevity of urban senior citizens is positively influenced by living in areas with green spaces in walking distances. Sugiyama and Ward Thompson (2007) also suggested that outdoor environments have an important role in older people’s well being.
There are many research on understanding and explaining the effects of urban landscape on human health. Although the links between health and green spaces remain missing, the literature review given above clearly display that urban landscape has positive impacts on improving both mental and physical health in several ways. It is landscape architect’s role to create outdoor environments which maximize the benefits of urban landscapes for citizens to relax, exercise and restore.
Although the economic valuation of urban landscape is difficult, open and green spaces have economic benefits in several ways:
• Their aesthetic contribution to cityscape influences property values. In general, urban landscape elements increase the nearby property value and enhance marketability of real estate (Anonymous, 2010). Accessibility, quality and visibility are basic factors that determine economic value of urban landscapes in this context.
• Urban landscapes provide employment opportunities during their design, construction and maintenance. The construction and maintenance of urban landscapes also supports other sectors such as playground manufacturers and nurseries.
• The health benefits of urban landscapes which were summarized above can reduce the costs of national health expenses.
• Public urban landscapes provide environments for walking, sports and other recreational activities for no cost at all, especially for lower income groups.
• Green spaces can help energy saving. Right selection and planting of plants can provide cooler environments in summer and warmer environments in winter thus reduce air conditioning expenses.
• Urban landscapes can enhance tourism in cities by attracting people. Park Guell in Barcelona, Spain is a perfect example of how a park can become a global tourism destination.