The way Duke University biologist Will Wilson sees it, there's more to in-town open space than making a place look nice. There are practical factors, too, and he's got the numbers to show it.

Now if City Hall will just get the message.

"It's sort of frustrating," he said last week.

Wilson's frustration is felt as an advisor on the City-County Planning Department's "Urban Open Space" project. The project, as phrased on the department's web site, is intended for "preservation and enhancement of open space in Durham's urban core."

Wilson, who gives "urban ecology" as one of his research interests, said he went into the planning with "high hopes," but as time went by found it was lacking in definite goals.

That may be about to change. The Planning Department called off a meeting on urban open space last week.

According to Senior Planner Helen Youngblood, the staff needs time "to properly assess where the plan is heading and thoroughly consider what the planning goals are."

Wilson has some ideas. In fact, he wrote the book about them: "Constructed Climates: A Primer On Urban Environments."

The University of Chicago brought it out earlier this year, a textbook full of charts and statistics on how city-center vegetation, or lack thereof, affects temperature, air quality, water quality and citizens' well being.

Satellite images in the book show an inverse correlation between heat and tree coverage in Durham County.

The city shows up as a "heat island," with temperatures as much as 10 degrees higher in town than in the country.

Higher temperatures correlate with air pollution, which correlates with increased intances of asthma, influenza and heart trouble.

Urban Durham provides examples of both healthy and unhealthy open spaces, Wilson said.

In the courtyard of Brightleaf Square, trees are planted between brick walls. The walls and pavement absorb heat and radiate it into the air, where the trees intercept it and release it to be carried away by the wind, he said.

"That's a way of getting urban heat out of the city."

On the other hand, in a treeless block of Market Street, "that radiation just sort of bounces between the trees and the road and ... it doesn't go away. That's how it causes these urban heat islands," Wilson said.

Vegetated open space also slows stormwater runoff and filters out some pollutants before they get into water supplies.

"We think it's really important," in terms of stormwater and the urban heat island, said Melissa Muir, special project director at Downtown Durham Inc. and another member of the Urban Open Space advisory committee.

DDI, she said, has some projects of its own to encourage measures such as "green roofs" on downtown buildings and other environmental protections.

City-County Sustainability Manager Tobin Freid is not involved in the urban open space planning, but said that, properly done, it "benefits both the environment and society as a whole."

Cooling and cleaning the air, she said, "enhances human, animal and plant life in a variety of ways, [and] studies have shown the psychological benefits."

Wilson also points out that trees are more common in affluent urban areas than in poor neighborhoods, suggesting that "preservation and enhancement of open space" in the inner city is a matter of social justice as well as public health and an improved environment.

So far, though, in Durham's planning, "those major goals sort of haven't been brought forward," Wilson said. "It's more like they're planning it like prettying up Durham, having more trees and shrubs but no real goals in mind."

Wilson has asked the InterNeighborhood Council to endorse "reduction of downtown temperatures, improvement of air quality, and rectifying issues related to environmental health and socioeconomic equity" in whatever plans are made.

"Why should taxpayers be spending money on open space downtown?" he said. "We should get something from it."