Paris Does Green Space (And Finds Great Success)

Paris green space articleWhy 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.
Green space in Paris. (Click to enlarge)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.

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.

Over the past decade, Frances 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.

[Read the full article from National Geographic here.]

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