Published: October 2006
Urban Downtime
The City of Light is also a city of green, with a panoply of parks and gardens where Parisians rest and rejuvenate.
By Jennifer Ackerman

That we should find nature rejuvenating is hardly surprising. After all, our tribe arose not in cinderbelt but in wild forests and grasslands. Our ears are made not for the stinging scream of sirens but for the sly scratch of a predator's paws and the whistle of wind that warns of impending weather. Our eyes evolved to tease apart not the monotonous grays of cityscapes but the subtle gold, olive, and burgundy hues that signaled ripe fruit and tender leaves, and our brains to reward our sensory efforts with feelings of deep pleasure.

Could this be why the citizens of Paris work so hard to reinvent dead urban space and neglected squares of hardscape as places of vibrancy and green? Consider Parc des Buttes-Chaumont in the city's crowded 19th arrondissement. Once this patch of land held an old gallows, then a gypsum quarry, then the city dump. Now the big bucolic park of grassy slopes and grottoes is alive with bloom and birdsong and a healthy jumble of people who spill onto its hilly lawns: kickboxers, musicians, university students perusing their notes or memorizing lines for a play, lovers rolling over one another like tumblers, and old men who have settled themselves on the grass to rest.

Parisians in fact will seize just about any spot in their city for park or garden: tiny balcony, abandoned auto plant, bankrupt parking garage, derelict railway, even the giant curved facade of a new museum. They will sacrifice broad boulevards for the sake of bike paths with leafy canopies. They will argue for community gardens over apartments or media centers. They will relinquish a busy city expressway along the Seine for a temporary beach park, and will see in every shabby lot a prospective cathedral of green.

Why are citizens of the City of Light so intent on finding space for parks and gardens, for street trees and nature strips? For that matter, why would any city go to the bother and expense of growing green space in the stone and steel of an urban environment? At a time when half the world's population lives in cities (a proportion expected to grow to 60 percent by 2030) and funds may be scarce for urban housing, schools, social services, fire and police protection, this is no trivial question.

It's true that in Paris, as in many other cities, parks and gardens are a luxury. "But they are also essential," says Martine Petelot, a member of the Jardin Nomade, a small community garden on a vacant lot in the congested 11th arrondissement. "Our garden allows us to work the earth, to watch things grow. People need to scratch about in the soil, breathe in the scent of plants and flowers, let off steam, and meet other people. For many, it's almost like therapy."

If the recent renaissance in urban parks and public spaces is any indication, many city residents and planners share Petelot's perspective. The past five to ten years have seen an explosion of tree planting in cities and the creation of new parks and public gathering spots—a revolution inspired in part by new science. A growing body of research suggests that spaces filled with leafy vegetation filter pollution and trap tiny particles of dirt and soot: Street trees can reduce airborne particulates from car and bus exhaust. Large groves of trees may have an even more profound green-lung effect for cities, cleansing the air of dangerous chemicals. In Chicago, scientists found that each year trees removed some 234 tons (212 metric tons) of particulates, 98 tons (89 metric tons) of nitrogen dioxide, 93 tons (84 metric tons) of sulfur dioxide, and 17 tons (15 metric tons) of carbon monoxide.

Tree leaves block sunlight as well, cooling islands of heat generated by hard city surfaces. The temperature of asphalt or concrete under a shade tree can be as much as 36°F (20°C) cooler than a patch of pavement in full summer sun; the air up under the canopy of mature trees may be five to ten degrees cooler.

Parks and gardens are also essential to human social and psychological well-being. Without access to grass and trees, says Frances Kuo, we humans are very different creatures. For the past decade, Kuo and her colleagues at the Landscape and Human Health Laboratory of the University of Illinois have researched the effects of green space on city dwellers. The team carries out many of its studies in Chicago's public housing neighborhoods, where barren expanses of hardscape reflect the old view that vegetation is an extravagance the city can't afford.

One sequence of studies focused on residents of the Robert Taylor Homes, a cluster of 28 identical high-rise buildings, now mostly torn down, that formed the nation's largest public housing development. Some of the buildings were surrounded by grass and trees, others by concrete and asphalt. Kuo and her team discovered that people living in buildings near green areas had a stronger sense of community and coped better with everyday stress and hardship. They were less aggressive and less violent, they performed better on tests of concentration, they managed their problems more effectively.

They also felt safer—and with good reason. In one of its more startling findings, the team upended the common belief that barren spaces are safer than green ones. A study of violent crime in a housing project of 98 apartment buildings showed that in and around buildings near vegetation that didn't hamper visibility there were only half as many crimes as in areas near no vegetation. The greener the surroundings, says Kuo, the lower the crime rate against people and property. The team also found less litter and graffiti in natural landscapes.

In their most recent research, a national study of 450 children ages five to eighteen, the scientists discovered that children with attention deficit disorders showed reduced symptoms when they were exposed to natural environments. After play in verdant settings, parents reported that the children's ability to concentrate, complete tasks, and follow directions improved dramatically—in all age groups, in all parts of the country.

Why would vegetation influence our mental well-being? For one thing, grass and trees provide a welcoming place for people to gather. In the hectic and crowded cores of cities, people need the little grove of chestnut trees outside their apartments where they can mingle in the shade and hear the hiss of wind in high trees. They need big public lawns where they can play together. They need the tiny sprouting plots of neighborhood gardens, where they can put aside the city's stress on time and the temporary in favor of growth and permanence.

Scientists suspect that green space also has a restorative effect on our voluntary attention, the kind of intense focus required to work or study, to ignore distractions and concentrate on the task at hand. Voluntary attention is like a mental muscle; we exercise it in nearly every aspect of our lives. It dictates how well we think and how we handle ourselves in difficult situations—whether we roll with the punches or fly off the handle. Living in a city with its relentless crush of noise and traffic, conflicts and demands, makes us "crabby and impulsive," Kuo says. Being in nature refreshes us by letting us give voluntary attention a rest and allowing us to surrender to involuntary attention: the effortless and often enjoyable noticing of sensory stimuli in our environment.

Kuo speculates that over the course of human evolution, there was selection for this response to the natural world. Our ancestors who found nature effortlessly engaging had an advantage. "They were the ones more likely to know where the berries could be found and where the critters hung out," she says. "When push came to shove in difficult environmental conditions, they were better able to survive."

In our modern era, with all its pressures, contact with nature in urban settings may be more crucial than ever. A park-rich metropolis helps us stay physically healthy and battle overweight and diabetes. Two big recent studies of people in populated urban centers in the Netherlands and Japan showed that those living in areas with easy access to green spaces where they could walk had significantly better health and lower mortality rates than those without. Health studies suggest that even relatively passive contact with nature lowers blood pressure and anxiety levels.

Politicians and planners may be getting the message. In 2003, the U.S. Conference of Mayors passed an urban forestry resolution to promote the preservation and new growth of trees and forests in city environments. Two years later, 50 city leaders from around the globe signed a Green Cities Declaration at the United Nations World Environment Day in San Francisco. Mayors from Delhi to Dakar, Moscow to Manila, resolved to chart a bold new course for the urban environment, launching efforts to reduce waste and pollution, ease traffic congestion, and—by the year 2015—to ensure an accessible public park or recreational open space within a third of a mile of every city resident.

"Reclaiming space so that a city can 'breathe' is an integral part of the challenges confronting urban civilization today," says Bertrand Delanoë, the popular mayor of Paris. "A modern city needs areas free from density, noise, and the frenzied urban pace. We must re-create the kinds of spaces that lend themselves to talking, walking, discovering, relaxing."

When Delanoë ran for office six years ago, a centerpiece of his campaign was a pledge to find, within city limits, 75 acres (30 hectares) for new parks and public spaces. In a metropolis as densely settled as Paris, this is no easy task. But Mayor Delanoë and his staff are recycling land with characteristic Parisian creativity and verve, rescuing bits and pieces of the city to create new parks.

Among them is Un Tracé de Verdure sur les Maréchaux, a linear greenway to be planted along a tram route in the south of Paris, and the Jardins d'Eole, a soon-to-open informal ten-acre people's park where residents of the working-class neighborhoods of the northern 18th arrondissement can picnic and play on fields that were once train yards. With these and other small parks and public spaces, including some of the 40 or so vibrant community gardens that have cropped up on vacant lots all over the city, Delanoë's promise will likely be fulfilled.

Champions of urban parks hail recent progress in the greening of cities but warn that much remains to be done. Some leaders consider their cities all built up, with no room for more parkland, says Peter Harnik, director of the Center for City Park Excellence at the Trust for Public Land in Washington, D.C. But if a city has space for one more building, Harnik posits, it has room for one more park.

As for footing the bill: Cities have traditionally reserved funds for such requisites as police, sewers, and fire trucks, and considered parks and green space as pleasant amenities—investments for leftover money. But researchers such as Frances Kuo argue that parks in cities represent a minor public investment with a huge payoff. "Parks help people take care of themselves so cities don't have to spend as much on social, medical, and safety services trying to fix their problems," she says.

What then should be the goal of city planners? A park near every doorstep where people can gather and gain a healthy dose of that remedy Henry David Thoreau said we can never have enough of: nature.