The urban model currently used in most cities prioritises mobility in private motor vehicles, a focus that has tended to reduce the frequency of walking and cycling, especially among children, for whom just a few decades ago these were the most usual modes of transport on school routes.
The use of urban space primarily for road traffic has a direct impact on aspects, such as air quality and physical activity, that determine the health of the population, and especially that of vulnerable groups like children and older adults.
Another issue closely linked to urban and transport planning is climate change—one of the greatest global challenges facing cities in the 21st century. The urban heat island effect, a phenomenon caused by heat accumulation due to the building materials that predominate in urban landscapes, is expected to become more acute and lead to an increase in the negative health effects caused by high temperatures, including impaired cognitive development and premature death.
Air pollution is a serious public health problem that causes more deaths than traffic accidents and affects the growth, respiratory function and cognitive development of children
Air pollution and climate change are two very different phenomena but their origins are closely related, as many of the emissions generated by the combustion engines that power motor vehicles not only degrade air quality but also contribute to climate change by aggravating the greenhouse effect.
Air pollution is a serious public health problem that causes more deaths than traffic accidents and affects the growth, respiratory function and cognitive development of children.
Over half of the pollutants inhaled every day by children are produced by motor traffic along school routes and in the areas around schools. Ensuring clean air in and around schools should be a priority for policy makers and air quality should be monitored more closely by the authorities.
Consequently, we need urban planning criteria that treat school routes, schoolyards and nearby areas as public spaces that must be healthy and adapted to the needs of climate change through the addition of vegetation, water elements and shade structures and by prioritising active transportation and limiting traffic. All of these strategies can be used to improve the health and physical and mental well-being of young people and the community as a whole, to promote environmental justice and reduce inequalities.
Mariona Gil / Barcelona City Council.
Did you know that... ?
- ...Almost 25% of our health is determined by the environment where we live.
- ... In Barcelona and Madrid, pollution causes as many as 800 premature deaths each year, and in Barcelona pollution levels in 50% of school environments are higher than the maximum European Union (EU) thresholds.
- ... Half of the pollutants that children are exposed to every day are produced by traffic along school routes and in and around schools.
- ... The smallest air pollutant particles can pass through the lungs into the bloodstream and reach all of the organs in the body, including the brain, where they may affect the child’s cognitive development.
- ... Studies have shown that, in addition to reducing traffic, having green spaces with trees less than 300 meters from your home is an effective way to reduce air pollution, temperatures and noise levels.
- ... Playing in natural areas characterised by high biodiversity improves children’s immune systems.
Urban Planning, Mobility and Health
According to the World Health Organisation (WHO), the environment where we live determines almost 25% of our health status. Adults living and children growing up in urban settings are increasingly exposed to high levels of air and noise pollution and tend to engage in less physical activity and have less contact with nature. Urbanisation is an ongoing process and current projections indicate that within the next 15 to 20 years 70% per cent of the world’s population will be living in urban areas.
Jobs, innovation and wealth creation continue to be the drivers of population growth in cities.
About 85% of the road space in Spanish cities is allocated to mobility and transport (cars, buses, taxis, bicycles and pedestrians), leaving less than 15% for areas where pedestrians have priority. In Madrid, 80% of the public space is allocated to private vehicles, despite the fact that they represent only 30% of the journeys made in the city. Barcelona and Lugo allocate 60%-70% and 46%, respectively, of public space to motor traffic and parking. This distribution is both unsustainable and inequitable in terms of both the environment and health. In the current pandemic situation, it has become even more essential to redistribute urban space and promote sustainable, safe and equitable mobility.
The design and management of public space can have a significant impact not only on the health and well-being of the population but also on education, social cohesion and the problems of equity within the community. Public areas can be natural and peaceful spaces designed to be restorative and reduce stress as well as to promote physical activity and play and to foster experimentation, creativity and critical skills in a sustainable way.
Figure 1. Conceptual framework of the relationships between health and the urban environment (Nieuwenhuijsen 2018).
Air Pollution
In Spanish cities, road traffic is the main source of air pollution, and air pollution is the cause of some of the most common diseases in our society, including lung cancer, stroke and respiratory diseases. But if our contact with polluted air occurs in the lungs, how do these pollutants get into the brain and our other organs? We know that airborne pollutant particles can penetrate the lung barrier, enter the bloodstream and travel to other organs, such as the kidneys, heart, brain and bones, where some are trapped by filters or neutralised and stored by our immune system. This accumulation of foreign particles generates chronic, low-level inflammation that has many negative health impacts. Recent research has shown that these particles can also reach the placenta and foetus during pregnancy and can even penetrate our brains.
Figure 2. The impact of air pollution on our health (ISGlobal. Digital report: 5 Keys to Healthier Cities).
Noise
Motor traffic also contributes significantly to noise pollution. In the EU, traffic noise is the second most harmful environmental factor after air pollution. The maximum exposure levels set by the latest WHO guidelines (2018) are lower than those recommended in earlier guidelines and specify different levels for each type of noise source. The maximum exposure level for road traffic recommended in the new document is 53 decibels (dB) average exposure over 24 hours and a maximum of 45 dB at night. For railway noise the safe upper threshold is 54 dB for the 24-hour average and 44 dB at night; and for aircraft noise the thresholds are 45 dB and 40 dB, respectively. Noise sources should be treated separated, as each type of noise has different characteristics and can give rise to different health effects. Current EU recommended thresholds for maximum noise exposure, which are based on the older WHO guidelines, are higher: 55 dB for the 24-hour average and 50 dB at night. Even so, 20% of the EU population (1 in 5 people) are exposed to environmental noise levels in excess of these recommended thresholds.
Several studies have shown that exposure to excessive noise is associated with stress/annoyance, sleep disturbances, heart disease, diabetes and obesity, premature death and impaired cognitive function. The mechanisms underlying these health problems involve hormonal and autonomic nervous system alterations caused by the perceived (annoyance) and unperceived (physiological) stress experienced by the individual as a result of chronic exposure to environmental noise. Several authors have also suggested that noise may be a risk factor for attention deficit and behavioural problems.
In the EU, traffic noise is the second most harmful environmental factor after air pollution
The annual statistics on people living in the EU exposed to harmful environmental noise levels of 55 dB or higher are as follows: 22 million, psychological stress (a chronic high level of annoyance); 6.5 million, high sleep disturbance; 48,000, new cases of heart disease; 12,000 premature deaths. In addition, it is estimated that 12,500 school children suffer impaired cognitive development due to daytime exposure to aircraft noise greater than 40 dB according to the WHO, exposure to excessive aircraft noise may be one of the preventable causes of child deafness. More locally, in the city of Barcelona, for example, exposure to noise levels above the recommended thresholds has been identified as one of the main factors associated with high levels of morbidity (i.e. burden of disease, ill health and disability) in the population, especially due to sleep disturbance and annoyance.
Environmental noise is a major public health problem. There is a need for interventions and legal limits on noise pollution in the EU. More epidemiological studies are also needed because the health effects may be even greater than previously reported and the WHO maximum thresholds for safe exposure are now lower and source specific.
Heat Islands
In urban and metropolitan areas, buildings, roads and parking lots are constructed with materials that absorb and store heat. This built environment has replaced green areas and natural open spaces, causing urban areas to become significantly hotter than nearby rural areas. This urban heat island effect, which is further aggravated by air pollution from vehicles and industrial activities, is one of the most significant changes in the climate on the Earth’s surface caused by human activity related to urban planning and transport practices. The phenomenon has increased and will increase more with climate change.
Figure 3. Urban heat islands and how they affect our health (ISGlobal).
Exposure to high temperatures is associated with increased morbidity and premature mortality, especially in children and older adults. In the city of Barcelona, for example, it has been estimated that exposure to temperatures higher than the safe thresholds recommended by international guidelines causes around 400 premature deaths every year.
Increasingly, sustainability criteria are being used to guide mobility planning in European cities to achieve a balance between mobility needs and access to basic services in the urban environment. The aim is to enable citizens to enjoy their neighbourhood and offer them safe, time-saving and energy-saving travel options while at the same time enhancing environmental protection, social cohesion and economic development. One clear example is the “15-minute city” or “urban proximity” model, which cities like Paris, Valencia and Bilbao are already considering. They are embracing a decentralised city model in which basic services—housing, workplace, health services, education, leisure and shopping—are all located within a 15-minute walk or bike ride. This model substantially improves the inhabitants’ health and quality of life by reducing the main source of urban pollution: travel in private vehicles. Increased levels of physical activity also promote social interaction and improve the integration of neighbourhood businesses.
This shift towards more sustainable cities and greater proximity also has a global dimension linked to the Sustainable Development Goals (SDGs) of the United Nations 2030 Agenda, adopted in 2015, which were formulated to guide the development of global society over the coming decade. Specifically, these new trends in the city planning model are aligned with SDG11 (Sustainable Cities and Communities) and all the targets related to improving the quality of life in cities and the proximity and equity of public services, spaces and facilities in urban environments.
Mi Pham / Unsplash.
Natural Spaces in the Urban Environment: The Health Benefits of Green and Blue Spaces
Our nervous system needs contact with vegetation and water, two important elements for our survival. Contact with nature is essential for the psychological development of the human being. The close relationship over millions of years between humans and their environment has created a profound emotional need in us to be close to other life forms, whether plants or animals. The body of scientific evidence on the benefits for our health and well-being of natural spaces (green and blue) has grown in recent years, driven by an emerging interest in the impact of biodiversity and the role ecosystems have on life in urban areas.
Urban green space is defined as any urban area (parks, gardens, woodland) covered with vegetation of any kind (trees, grass, shrubs or flowers), public or private, and irrespective of its size and function.
Blue spaces are defined as any visible expanse of water, whether natural (lakes, rivers, streams, the sea) or artificial (fountains, ponds in parks, etc.).
Contact with the natural environment, whether in the form of green spaces or aquatic environments, has positive effects on the physical and mental health of both adults and children.
Figure 4. Green and blue spaces (ISGlobal).
It has been observed that, independent of urban density, the proximity of green infrastructure is associated with better self-perceived general health and better mental health, probably due to the fact that green spaces reduce stress. It has also been observed that residence in areas with more green space lowers mortality, in particular death from cardiovascular disease. An increase of 0.1 in the vegetation index close to a person’s place of residence could be associated with a 4% reduction in all-cause mortality. Green spaces have also been associated with improved respiratory health and less obesity, better mental health and an appreciation of nature in adulthood. It has also been shown that, in the medium to long term, exposure to green spaces plays a role in the prevention of metabolic syndrome (obesity, hypertension and high levels of body fat and blood sugar), especially in places with more trees.
These health benefits can probably be explained by a combination of several factors: improved air quality, lower temperatures and reduced thermal stress, increased physical activity, greater social interaction and a sensation of psychological restoration.
In short, our health and the health of our planet depend on the design of our cities. Urban life now poses challenges that require rethinking the way we plan urban environments. The #CitiesWeWant are cities designed for people: places where we can live well and be healthy.
Figure 5. The Five Keys to Healthy Cities. #CitiesWeWant.
Natural Land Cover Sequesters CO2, Cools the Environment, Promotes Social Cohesion, and Reduces Air Pollution and Noise
As cities come to the realisation that one of the major challenges they face is the impact of climate change on their development, urban planning programmes aimed at creating greener and more natural environments are becoming increasingly widespread. However, an important aspect that must not be overlooked in the design and implementation of natural spaces in cities is who will benefit from the changes.
Green spaces represent a large part of the open public spaces and common services provided by a city. They should, therefore, promote healthy living, serve all sections of the community and be equitably distributed throughout the city. It is essential to ensure that public green spaces are easily accessible to the whole population. All too often, redevelopment projects that increase the natural land cover in an urban area lead to the displacement of the more socially vulnerable groups living in the area, who are replaced by healthier and more educated populations with higher income levels. This process of “green gentrification” generates urban patterns characterised by inequitable distribution of the natural spaces and resources of high social value. Urban greening research must study all the different aspects of the topic, including the social and ecological implications, due to the complexity of how natural spaces are integrated into the urban fabric. This is particularly relevant in cities where social and ecological components, including green spaces, are under pressure as a result of progressive urbanisation.
Asia Culture Center (Gwangju, South Korea) / Unsplash.
In recent years, these emerging social challenges have given rise to a new concept: nature-based solutions (NBS). NBS are defined as sustainable solutions focused on involving people in nature-based experiences to promote improved physical, mental and social health and well-being. A study that identified a wide range of NBS concludes with a call for research to identify the drivers that influence the effectiveness of NBS in enhancing health and well-being.
NBS can serve as climate change mitigation and adaptation tools while also producing additional benefits for societal well-being. They are, therefore, an excellent investment option for sustainable urban planning that can be applied to public spaces, such as schools, which host some of society’s most vulnerable groups. Effective urban planning based on scientific evidence and aimed at reducing the urban heat island effect, and therefore temperatures, must include a range of mitigation strategies, such as water and vegetation, since water bodies and water features play an important role in surface temperature dynamics. For example, trees planted around bodies of water help to maximise the benefit because they increase the air cooling effects of the water.
These new trends represent a change in how nature is viewed in the field of public health, as a potential tool for the treatment and prevention of health problems rather than solely as a risk factor.
Urban green infrastructure also reduces air pollution, in particular airborne particulate matter (PM), which is removed by way of dry deposition on leaf surfaces. The ability of certain tree species to retain airborne pollutants may go some way to explain their association with improvements in mental and cognitive health observed in some studies. This association has been a subject of research in the United States for many years. A study of 55 cities in 2006 estimated the total air pollution (ozone, PM, NO2, sulfur dioxide and carbon monoxide) removed by urban trees at 711,000 tons per year, resulting in a reduction of 850 deaths and over 670,000 cases of acute respiratory episodes per year. In 2018, the pollution absorbed by the 5.7 million trees in the city of Madrid (principally stone pine, plane trees and holm oaks) was quantified for the first time. The study estimated that the trees prevented more than 3,600 asthma episodes and 4,000 episodes of acute respiratory symptoms per year, generating savings of 25.7 million euro.
Many cities are increasing their natural land cover and green space by creating green corridors, new parks and living walls, as well as by adding vegetation to the roofs of buildings and schools. Urban greening also helps to adapt cities to climate change, improves liveability, increases the attractiveness of neighbourhoods and has health benefits.
The proximity of green spaces to people is another factor that influences the effectiveness of urban greening in reducing temperatures and airborne particle levels. Mitigation is most effective when the trees are less than 300 metres from people (residential areas, schools, etc.). Access to open and public green spaces is associated with increased physical activity, better quality of life, life satisfaction, social cohesion, stress reduction, restoration of well-being and improved physical and mental health. Open and public green spaces encourage people to stop, linger and gather on neutral ground and to engage in planned and unplanned social and cultural activities and encounters. This activity helps to foster a sense of community and belonging and strengthen social cohesion.
Urban greening is also an effective way of reducing noise pollution. On the one hand, green infrastructure reduces the public space allocated to motor vehicles, thereby reducing road traffic, the principal source of noise. On the other hand, vegetation can be used to create a natural screen to cushion and absorb noise. Two particularly effective strategies for this purpose are green walls and combination plantings of shrubs and evergreen trees that do not shed their leaves seasonally and will therefore mitigate noise year round. Replacing roads and car parking spaces with NBS is a good way to move away from an urban environment harmful to health and towards one that offers health benefits. Many cities are increasing their natural land cover and green space by creating green corridors, new parks and living walls, as well as by adding vegetation to the roofs of buildings and schools. Urban greening also helps to adapt cities to climate change, improves liveability, increases the attractiveness of neighbourhoods and has health benefits.
Chuttersnap / Unsplash.
In a world affected by continuous warming, trees play a key role in making cities more comfortable and functional. The air cooling achieved by tree canopies helps make the summer months in the city more tolerable. The benefits of trees can be measured not just in terms of improved air quality and health but also in economic terms. In London, for example, it has been estimated that the city’s trees saved the capital about 6 million euro between 2014 and 2018 through savings in air conditioning and higher productivity in the work environment in the summer months. Another example of the adaptation and contribution to urban planning of NBS is the installation, in the City of Utrecht, on over 300 bus stops of green roofs that capture fine particles of airborne pollutants, store rainwater and cool the spaces during the summer months.
Green walls or facades—also known as vertical gardens or living walls—are another effective element that can be used to mitigate the effects of heat and improve thermal comfort. Green walls are vertical planting systems that include an integrated substrate, live vegetation and, in some cases, an automated irrigation system. Living walls provide a greater benefit in terms of thermal comfort for people than green roofs because they act as an insulating layer that wraps around buildings and other surfaces, reducing the absorption and storage of heat. The lower surface temperatures obtained reduce the amount of energy emitted by the wall, thereby providing the added advantage for thermal comfort of reducing average radiant temperatures.
In a world affected by continuous warming, trees play a key role in making cities more comfortable and functional.
In recent years, there has been growing interest in investigating the potential health benefits of blue spaces, although the scientific evidence is still limited and inconclusive. More studies are needed to assess the health benefits of water in the urban environment and to understand the mechanisms that underpin the relationship between blue spaces and health. Several studies have observed an association between living close to the coast and better general and mental health and enhanced psychological restoration (feeling calm, relaxed, revitalised and refreshed). It has also been found that short 20-30 minute walks in environments close to water can have benefits for both mood and well-being. It has also been shown that outdoor physical activity, in particular walking, explains only part of the health and welfare benefits associated with living near the coast. More research is needed to explore what other mechanisms might explain those benefits. A clear correlation has been found between proximity to water and improvement in indicators of physical and psychological health. Spending time near water promotes physical activity, reducing the incidence of diabetes and other diseases associated with obesity.
To counteract the unstoppable rise in temperatures during increasingly earlier and more intense heat waves, cities have implemented different strategies for using water to refresh urban spaces: artificial lakes, more drinking fountains, water features designed to facilitate bathing and spraying, and water-themed recreation or play areas with splash pads. Splash pads have been shown to contribute to a change in the play habits of children and the community, creating a refreshing, inclusive, stimulating and safe environment where everyone can come to cool off during the hottest times of the year. Fountains can reduce the temperature of the surrounding air by as much as 3 °C and the cooling effect is noticeable up to 35 metres away. Water bodies also influence the microclimate around them, cooling through evaporation and mitigating the urban heat island effect. In contrast to large urban masses, prone to considerable heat absorption, fountains are an effective strategy for generating microclimates in relatively small areas, such as school yards.
Ildigo / Pixabay
To maximise cooling, water features should be active, mixing air and water to promote evaporation and cooling. A fountain that creates a mist by spraying water into the air cools more effectively. This cooling generates a refreshing, tranquil and aesthetically pleasing environment that can help to enhance physical and mental well-being while improving creativity, increasing physical activity and favouring better sleep quality. Another advantage of active water features is the sound they make, which can relieve stress and relax the listener as well as providing an aesthetic experience that generates a pleasant environment. Water in movement cools the air, reduces noise and makes for a pleasant and attractive space. The sound of running water has been shown to be effective in reducing epinephrine and cortisol, two stress hormones associated with many health conditions when levels are high.
Running water also generates negative ions, which purify the air and can have beneficial health effects. Air conditioners and other electronic devices deplete the negative ions in air, while water fountains and waterfalls introduce ions into the air. It is thought that negative ions increase levels of certain neurotransmitters, such as serotonin, which enhance mood and favour a sense of calm as well as increasing energy and improving alertness, and concentration. Water fountains also have social effects: children play in the water and adults enjoy fountains in parks and squares, which become meeting places for the community. Research has shown that increasing school-time exposure to blue spaces, either through recreational activities or simply due to the proximity of blue spaces, can play a significant role in promoting equitable health and also benefits social interaction.
Conclusions
In light of the growing weight of urban environments in recent decades and the health risks associated with this trend, we need to rethink the urban model and begin to prioritise renaturalisation and sustainability.
In light of the growing weight of urban environments in recent decades and the health risks associated with this trend, we need to rethink the urban model and begin to prioritise renaturalisation and sustainability
Our aim should be to recover public spaces for people. To do this, we must put a high priority on making our cities greener, minimising traffic, promoting more active modes of transport, and reducing noise and pollution levels. We must design our city models to promote health and well-being by providing better air quality, favouring psychological restoration and stress reduction, and encouraging higher levels of physical activity. We also need to increase social interaction and stimulate play among children. We must demand changes in mobility patterns, which currently depend mainly on the widespread use of private motor vehicles. This change is essential to protect the health of the whole population, and especially that of the most vulnerable groups in our society, such as children.
