Public space in cities – “lungs of the city”, indicators, and science on benefits

Mexico City’s Chapultapec Park provides residents a place to relax, play and interact with nature. Photo by Ben Welle/Flickr.

The famed American landscape architect and Central Park designer Fredrick Law Olmsted said that parks are the “lungs of the city.” However, many cities around the world—from growing Addis Ababa to sprawling Mumbai and dense Sao Paulo—currently lack adequate public space and find it difficult to breath.  Even Pope Francis devoted considerable space in his encyclical to writing about the importance of green public space and access to such space.

Indeed, public green spaces—from parks and plazas to natural areas, recreation areas, playgrounds, greenways or traditional squares—provide critical space for residents to breath and be active. Studies have shown they can improve air quality and reduce storm water runoff to provide ecosystem services and help raise property values. They also contain routes for walkers and cyclists and, along with other active uses, have been linked to greater physical activity and more active cities.

The new Sustainable Development Goals (SDGs) acknowledge the value of public space in creating sustainable cities, but the challenge now is to figure out how to define and measure public space—as well as access to it. By looking at existing methodologies and considering additional indicators on accessibility, cities may find an effective path for meeting their goals.

Public Space as a Development Goal

Target 11.7 of the SDG on cities is to “provide universal access to safe, inclusive and accessible, green and public spaces, particularly for women and children, older persons and persons with disabilities.” In February 2016, the Sustainable Development Goal Network proposed an indicator for this target as “the average share of the built-up area of cities that is open space for public use for all, disaggregated by age group, sex and persons with disabilities.”

So how would this get measured? The proposed indicator refers to “open space for public use” and not necessarily public green space, streets or privately-owned space. This makes the indicator difficult to track given the lack of a proper inventory, or a clear definition for what makes a private space open for public use. If a parking lot available to the public is “open space for public use for all,” does it count? “Open space” is actually a term used very generally, such as by architects for anything that is not built up. One option would be to change the indicator to “public space,” as this is the actual purpose of the target. In any case, on a practical level cities will need to determine what is public, or “public use” and what is not. Furthermore, it would be difficult to disaggregate this by age and sex, given that the indicator is about land, not people.

Most public space is actually a city’s streets, which UN-HABITAT has documented nicely in a report on streets as public spaces. The rest is public green space: natural areas, parks, plazas and playgrounds. Public green spaces are hard to measure because they fall under the jurisdiction of numerous government entities—or as the proposed indicators’ “open space,” any kind of publicly-available open area.

This is why a common methodology for measuring public space will be necessary. Today, most cities lack a clear protocol or standard guide for how they might measure these spaces, let alone an existing inventory or understanding of the public agencies involved in public space (e.g. cities can have both city-owned parks and national parks). Google maps might have a better inventory of a city’s public space than the city itself.

Looking to Existing Standards

One model can be found in the United States, where information about public space has been extensively developed and improved over the years through the Trust for Public Land’s Center for City Park Excellence yearly survey of park systems. The survey includes all types of public spaces in over 75 of the country’s largest cities, from natural areas to traditional city parks and plazas. The Global City Indicators Facility also uses a similar classification, calling these spaces “green areas.”

While simply applying these existing methodologies to an entire globe of different cities may not be appropriate, there are some basic principles that cities can use to measure public space. Cities can inventory the spectrum of spaces, from natural areas to small neighborhood parks owned by different government entities. For example, in some cities, cemeteries are publicly available spaces run by the city park and recreation department. A basic guide is needed that can build on these methodologies, define and inventory spaces and be potentially used in a first round of selected indicator cities.

Another Complication: the Question of Genuine Access to Public Space

Cities vary considerably in size, history, development patterns and attitudes towards public space. Measuring how much public space a city has is only one part of measuring whether residents actually benefit from the space. For this reason, an additional indicator may be helpful on the accessibility of public green spaces. This could serve as a component of a greater indicator for cities (as the World Bank has suggested) on accessibility to destinations, including access jobs, goods and services.

For example, Sao Paulo, Brazil has approximately 12.4 square meters per resident of public green space, yet this space is not distributed equitably across the city. To remedy this, the city’s new Plano Direto seeks to create 167 new parks to get parks closer to people. Minneapolis, often considered the city with the best park system in the United States, has 14.9 percent of its land area dedicated to public green space, but is recognized for its connectivity and accessibility, as 94 percent of residents are within a ten-minute walk of a park. A simple indicator measuring the amount of public space does not capture this. Adding access to public spaces is the next step for the indicator.

Next month, officials and experts will gather in Barcelona to discuss the role of public space in the New Urban Agenda for the United Nations and UN-HABITAT. This will also coincide with further discussion on the SDG indicators late March in Mexico City. Creating good measures for public space will ensure that public space genuinely counts when it comes to residents’ quality of life.

Scientists are beginning to find evidence that being in nature has a profound impact on our brains and our behavior, helping us to reduce anxiety, brooding, and stress, and to increase our attention capacity, creativity, and ability to connect with other people.

“People have been discussing their profound experiences in nature for the last several hundred years—from Thoreau to John Muir to many other writers,” says researcher David Strayer, of the University of Utah. “Now we are seeing changes in the brain and changes in the body that suggest we are physically and mentally more healthy when we are interacting with nature.”

While he and other scientists may believe nature benefits our well-being, we live in a society where people spend more and more time indoors and online—especially children. Findings on how nature improves our brains bring added legitimacy to the call for preserving natural spaces—both urban and wild—and for spending more time in nature in order to lead healthier, happier, and more creative lives.

Here are some of the ways that science is showing how being in nature affects our brains and bodies.

1. Being in nature decreases stress

It’s clear that hiking—and any physical activity—can reduce stress and anxiety. But, there’s something about being in nature that may augment those impacts.

In one recent experiment conducted in Japan, participants were assigned to walk either in a forest or in an urban center (taking walks of equal length and difficulty) while having their heart rate variability, heart rate, and blood pressure measured. The participants also filled out questionnaires about their moods, stress levels, and other psychological measures.

Results showed that those who walked in forests had significantly lower heart rates and higher heart rate variability (indicating more relaxation and less stress) and reported better moods and less anxiety than those who walked in urban settings. The researchers concluded that there’s something about being in nature that had a beneficial effect on stress reduction, above and beyond what exercise alone might have produced.

We evolved to be more relaxed in natural spaces.

In another study, researchers in Finland found that urban dwellers who strolled for as little as 20 minutes through an urban park or woodland reported significantly more stress relief than those who strolled in a city center.

The reasons for this effect are unclear, but scientists believe that we evolved to be more relaxed in natural spaces. In a now-classic laboratory experiment by Roger Ulrich of Texas A&M University and colleagues, participants who first viewed a stress-inducing movie and were then exposed to color/sound videotapes depicting natural scenes showed much quicker, more complete recovery from stress than those who’d been exposed to videos of urban settings.

These studies and others provide evidence that being in natural spaces—or even just looking out of a window onto a natural scene—somehow soothes us and relieves stress.

2. Nature makes you happier and less brooding

I’ve always found that hiking in nature makes me feel happier, and of course decreased stress may be a big part of the reason why. But, Gregory Bratman, of Stanford University, has found evidence that nature may impact our mood in other ways, too.

In one 2015 study, he and his colleagues randomly assigned 60 participants to a 50-minute walk in either a natural setting (oak woodlands) or an urban setting (along a four-lane road). Before and after the walk, the participants were assessed on their emotional state and on cognitive measures, such as how well they could perform tasks requiring short-term memory. Results showed that those who walked in nature experienced less anxiety, rumination (focused attention on negative aspects of oneself), and negative affect, as well as more positive emotions, in comparison to the urban walkers. They also improved their performance on the memory tasks.

Nature may have important impacts on mood.

In another study, he and his colleaguesextended these findings by zeroing in on how walking in nature affects rumination—which has been associated with the onset of depression and anxiety—while also using fMRI technology to look at brain activity. Participants who took a 90-minute walk in either a natural setting or an urban setting had their brains scanned before and after their walks and were surveyed on self-reported rumination levels (as well as other psychological markers). The researchers controlled for many potential factors that might influence rumination or brain activity—for example, physical exertion levels as measured by heart rates and pulmonary functions.

Participants who walked in a natural setting versus an urban setting reported decreased rumination after the walk, and they showed increased activity in the subgenual prefrontal cortex, an area of the brain whose deactivation is affiliated with depression and anxiety—a finding that suggests nature may have important impacts on mood.

Bratman believes results like these need to reach city planners and others whose policies impact our natural spaces. “Ecosystem services are being incorporated into decision making at all levels of public policy, land use planning, and urban design, and it’s very important to be sure to incorporate empirical findings from psychology into these decisions,” he says.

3. Nature relieves attention fatigue and increases creativity

Today, we live with ubiquitous technology designed to constantly pull at our attention. But many scientists believe our brains were not made for this kind of information bombardment, and that it can lead to mental fatigue, overwhelm, and burnout, requiring “attention restoration” to get back to a normal, healthy state.

Strayer is one of those researchers. He believes that being in nature restores depleted attention circuits, which can then help us be more open to creativity and problem-solving.

“When you use your cell phone to talk, text, shoot photos, or whatever else you can do with your cell phone, you’re tapping the prefrontal cortex and causing reductions in cognitive resources,” he says.

In a 2012 study, he and his colleagues showed that hikers on a four-day backpacking trip could solve significantly more puzzles requiring creativity when compared to a control group of people waiting to take the same hike—in fact, 47 percent more. Although other factors may account for his results—for example, the exercise or the camaraderie of being out together—prior studies have suggested that nature itself may play an important role. One in Psychological Science found that the impact of nature on attention restoration is what accounted for improved scores on cognitive tests for the study participants.

This phenomenon may be due to differences in brain activation when viewing natural scenes versus more built-up scenes—even for those who normally live in an urban environment. In a recent study conducted by Peter Aspinall at Heriot-Watt University, Edinburgh, and colleagues, participants who had their brains monitored continuously using mobile electroencephalogram (EEG) while they walked through an urban green space had EEG readings indicating lower frustration, engagement, and arousal, and higher meditation levels while in the green area, and higher engagement levels when moving out of the green area. This lower engagement and arousal may be what allows for attention restoration, encouraging a more open, meditative mindset.

Being in nature restores depleted attention circuits.

It’s this kind of brain activity—sometimes referred to as “the brain default network”—that is tied to creative thinking, says Strayer. He is currently repeating his earlier 2012 study with a new group of hikers and recording their EEG activity and salivary cortisol levels before, during, and after a three-day hike. Early analyses of EEG readings support the theory that hiking in nature seems to rest people’s attention networks and to engage their default networks.

Strayer and colleagues are also specifically looking at the effects of technology by monitoring people’s EEG readings while they walk in an arboretum, either while talking on their cell phone or not. So far, they’ve found that participants with cell phones appear to have EEG readings consistent with attention overload, and can recall only half as many details of the arboretum they just passed through, compared to those who were not on a cell phone.

Though Strayer’s findings are preliminary, they are consistent with other people’s findings on the importance of nature to attention restoration and creativity.

“If you’ve been using your brain to multitask—as most of us do most of the day—and then you set that aside and go on a walk, without all of the gadgets, you’ve let the prefrontal cortex recover,” says Strayer. “And that’s when we see these bursts in creativity, problem-solving, and feelings of well-being.”

4. Nature may help you to be kind and generous

Whenever I go to places like Yosemite or Big Sur, on the coast of California, I seem to return to my home life ready to be more kind and generous to those around me—just ask my husband and kids! Now some new studies may shed light on why that is.

In a series of experiments published in 2014, Juyoung Lee, GGSC director Dacher Keltner, and other researchers at the University of California, Berkeley, studied the potential impact of nature on the willingness to be generous, trusting, and helpful toward others, while considering what factors might influence that relationship.

As part of their study, the researchers exposed participants to more or less subjectively beautiful nature scenes (whose beauty levels were rated independently) and then observed how participants behaved playing two economics games—the Dictator Game and the Trust Game—that measure generosity and trust, respectively. After being exposed to the more beautiful nature scenes, participants acted more generously and with more trust in the games than those who saw less beautiful scenes, and the effects appeared to be due to corresponding increases in positive emotion.

I seem to return to my home life ready to be more kind and generous.

In another part of the study, the researchers asked people to fill out a survey about their emotions while sitting at a table where more or less beautiful plants were placed. Afterwards, the participants were told that the experiment was over and they could leave, but that if they wanted to they could volunteer to make paper cranes for a relief effort program in Japan. The number of cranes they made (or didn’t make) was used as a measure of their “prosociality” or willingness to help.

Results showed that the presence of more beautiful plants significantly increased the number of cranes made by participants, and that this increase was, again, mediated by positive emotion elicited by natural beauty. The researchers concluded that experiencing the beauty of nature increases positive emotion—perhaps by inspiring awe, a feeling akin to wonder, with the sense of being part of something bigger than oneself—which then leads to prosocial behaviors.

Support for this theory comes from an experiment conducted by Paul Piff of the University of California, Irvine, and colleagues, in which participants staring up at a grove of very tall trees for as little as one minute experienced measurable increases in awe, and demonstrated more helpful behavior and approached moral dilemmas more ethically, than participants who spent the same amount of time looking up at a high building.

5. Nature makes you “feel more alive”

With all of these benefits to being out in nature, it’s probably no surprise that something about nature makes us feel more alive and vital. Being outdoors gives us energy, makes us happier, helps us to relieve the everyday stresses of our overscheduled lives, opens the door to creativity, and helps us to be kind to others.

No one knows if there is an ideal amount of nature exposure, though Strayer says that longtime backpackers suggest a minimum of three days to really unplug from our everyday lives. Nor can anyone say for sure how nature compares to other forms of stress relief or attention restoration, such as sleep or meditation. Both Strayer and Bratman say we need a lot more careful research to tease out these effects before we come to any definitive conclusions.

Still, the research does suggest there’s something about nature that keeps us psychologically healthy, and that’s good to know … especially since nature is a resource that’s free and that many of us can access by just walking outside the door. Results like these should encourage us as a society to consider more carefully how we preserve our wilderness spaces and our urban parks.

Something about nature makes us feel more alive and vital.

And while the research may not be conclusive, Strayer is optimistic that science will eventually catch up to what people like me have intuited all along—that there’s something about nature that renews us, allowing us to feel better, to think better, and to deepen our understanding of ourselves and others.

“You can’t have centuries of people writing about this and not have something going on,” says Strayer. “If you are constantly on a device or in front of a screen, you’re missing out on something that’s pretty spectacular: the real world.”

How Public Spaces Make Cities More People-Oriented

Picnic Mexico City Public Space

Picnickers in Mexico City reclaim a freeway median as public space. Photo by Ben Welle/Flickr.

Nossa Cidade (“Our City”), from TheCityFix Brasil, explores critical questions for building more sustainable cities. Every month features a new theme. Leaning on the expertise of researchers and specialists in WRI’s sustainable urban mobility team in Brazil, the series will feature in depth articles on urban planning, sustainable mobility, gender, resilience, and other key themes for sparking more sustainable development in our cities.


In the late 19th century, the car emerged as a promise of freedom and independence. Could anyone have imagined at the time that after more than a century of development, that we would now be moving the opposite direction, returning streets to their main function—as public spaces for people?

Many public areas have been gradually forgotten—no longer safe living spaces that move people. In order for cities to be vibrant and safe places, we need to think of them as systems of interdependent parts and complex connections, as interactive and social spaces. Reclaiming urban spaces for people is part of how we can humanize our cities and make our streets more communal. Public spaces are often more than anonymous places that can be replaced with one another: the meetings and exchanges that occur here affect our relationships with each other, giving meaning to our communities and urban landscapes.

Previously in our series, we talked about the role that public spaces play in cities as vibrant centers of social interaction, economic activity, and urban greenery. Now, we’re taking a look at some examples of these spaces and how they’ve become vital to the communities they serve. These initiatives have changed their local communities, returning the streets to whom they rightfully belong: people.

The High Line, New York City

Green spaces in cities, such as New York's High Line, promote an active, sustainable lifestyle for city residents. Photo by David Berkowitz/Flickr.

Green spaces in cities, such as New York’s High Line, promote an active, sustainable lifestyle for city residents. Photo by David Berkowitz/Flickr.

The High Line in New York is often considered one of the greatest examples in the world of how idle urban space was revitalized. Built on an unused railway, the elevated park has turned an area of New York once full of violence and crime into one of the liveliest public areas of the city. The initial proposal was to demolish the old railway. However, Friends of the High Line was founded to advocate for preserving the railway. With plenty of greenery and pedestrian infrastructure, the park stretches over 2.3 km in one of the busiest areas of New York—on the west side of Manhattan—and attracts millions of visitors every year. The High Line is an iconic example of how people can reuse neglected parts of the city to improve quality of life for local residents.

Banks of the Seine, Paris

Reinventing waterfronts, like the Seine River in Paris, is one way that cities are revitalizing urban spaces for public use. Photo courtesy of the Paris Mayor’s Office.

Revitalization of the Seine River waterfront in Paris, Berges de la Seine, began in 2010 with a series of public consultations and a goal of returning the river to residents. A stretch of land about 2.5 kilometers long between the Pont Royal and the Pont de l’Alma was closed to cars and re-oriented toward people. The project has radically changed the waterfront by implementing sports facilities, art installations, space of musical performances, restaurants, and open space for leisure. Furthermore, the Jardin Flottant floating garden of 1,800 square meters connects five islands to each other. Each of these man-made islands has a different identity and varying vegetation, representing the Seine’s natural species. Blogger and journalist Renata Rocha Inforzato maintains an online guided tour of the waterfront, documenting how this space contributes to the vibrant center of the French capital.

People St, Los Angeles 

PeopleSt in Los Angeles

PeopleSt in Los Angeles is one example of residents using tactical urbanism to reclaim public space and make their streets more human-centered. Photo by LA DOT/Flickr.

People St is a program created by the Los Angeles Department of Transportation that allows residents—through partnerships and community centers—to request parkletsplazas, and bicycle corrals in their communities. By providing pre-approved models, People St cuts out the bureaucracy that typically stalls these projects. Plaza projects account for the largest share of their programs, and two successful case studies have emerged since the launch of the initiative: the Sunset Triangle Plaza, created in 2012 in Silver Lake, and the NoHo Plaza in North Hollywood. These projects often involve closing the street to cars, completely transforming streets into people-oriented gathering spots with tables, chairs, umbrellas, greenery, and more.

Tactical Urbanism

Tactical urbanism in Antofagasta, Chile

Two men sit at a makeshift concrete table in Antofagasta, Chile, where tactical urbanism is a growing trend. Photo by Pablo Guerra/Flickr.

Tactical urbanism brings several possibilities under one umbrella term. The movement encourages residents to make small interventions to city spaces to improve public spaces. These often low-cost projects are designed to transform empty spaces, and initiatives may range from something relatively simple like revamping a space in disuse, to constructing a Parklet. However, the goal is the same: to return street space to people .

One example is the Better Block, which began in Dallas five years ago. Using cheap and recycled materials, the group turned one block in the Oak Cliff neighborhood into a pleasant and attractive environment. Musicians, artists and local merchants were invited to join the initiative, which installed bike paths, street furniture, vegetation and temporary kiosks, increasing space for people and decreasing space for cars. The initiative has changed the face of the neighborhood, from empty and seldom used to cheerful and vibrant.

Facilitating simple changes, tactical urbanism encourages people to take ownership of their communities and rethink how their meetings and exchanges enable vibrant public spaces. In Brazil, two examples are Passanela and Oficina de Mobilario, a furniture workshop organized by Cidade Ativa. Passanela produced a skywalk over Rebouças Avenue in São Paulo, in order to increase pedestrian accessibility. The Cidade Ativa workshop did the same with the Steps of Alves Guimarães, adding street furniture to areas around the stairs, creating a space where people can stop to rest and chat.

Brazil Tactical Urbanism Passanela

Photos by the Passanela Project and Cidade Ativa.

Streets as Public Spaces

Long-term planning as well as rapid and inexpensive transformation strategies can be powerful tools to encourage public participation and improve quality of life. When it comes to public spaces, we think of parks, squares and green areas, often forgetting streets, which collectively are usually the largest public space in cities. The way in which streets are used, for the movement of people or vehicles, will define the environment around them. The first step in making cities safer and more pleasant places to live is to get residents to view their streets as public spaces.

This article was originally published in Portuguese on TheCityFix Brasil.

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