Philadelphia has invested in dozens of urban greening projects to prevent stormwater runoff. Now a team of mapmakers and data analysts is tracking those improvements to figure out if they influence public health.

"There's this idea out there, that green space is good for us, it's healthy for us. It helps our mental health, it helps our physical health, our ability to concentrate, that it may bring our stress levels down, that it is a preventer of crime or our fear of crime. So we have this idea but it has largely been unproven," said research scientist Michelle Kondo with the USDA Forest Service. 

While the city is working to upgrade its aging sewer system, there have also been dozens of "green" projects to help deal with flooding and polluted-water problems.

The city's "gray infrastructure" includes the underground pipes and huge storage tanks that no one ever sees. "Green infrastructure" includes landscape design, parks, rooftop gardens and trees that help slow down and sop up excess water before it becomes a problem. There are now dozens of "green" storm water management projects across Philadelphia.

Kondo says when you run water in the sink, or flush a toilet or when it rains in Philadelphia, all that water flows to the same set of pipes.

"That's all fine unless it's raining really hard," Kondo said. Untreated water backs up in people's basements and overflows into the street.

"Before we had cities, and all this pavement and concrete, the earth was pretty good at managing storm water, right, the rain fell and it was routed underground or into rivers," Kondo said. "People have sort of fouled up the system."

Monitoring health and crime through maps 

Kondo studies public health and urban environmental health from her field station in downtown Philadelphia.

Mapping is among her tools to greatly simplify the work: Kondo draws a circle around each site, then adds data on the health of the people who live nearby. From surveys, she can tell which areas have elevated rates of high blood pressure or cholesterol problems, for example. She also maps crime statistics near each area, including assaults, burglaries and drug possession.

"I'm looking at how many crimes were there in Year 1 and Year 2, Year 3, Year 4, and then the project was built in Year 4--so then--how many were there in Year 5, Year 6 and Year 7 and so on," Kondo said.

As green sites get built, you can watch on a movie map (at the bottom of this article) as red "hot spots" of narcotics crimes shift. At different geographic distances from the project—there is as much as 27 percent fewer narcotics-possessions near green projects, compared to control sites that received no improvements.

"People always ask, couldn't it just be gentrification that's causing these improvements?" Kondo said.

"I used maps to make sure I was comparing "apples to apples" that it wasn't something like demographics, gentrification, or even other greening projects that was causing the change in health/crime outcome," Kondo said.

Maps also helped the researchers understand if crimes were being "displaced"—simply pushed away from green projects to other parts of the neighborhood.

Kondo, said for her, an increase in public safety counts as public health.

A bump in health or a drop in crime at just one site doesn't mean much, but Kondo says when you track 52 sites over more than a decade, a picture emerges that green projects offer an add-on public health benefit.

Kondo did not find strong evidence that urban green projects reduce people's stress or drive down high blood pressure, but she says green improvements signal that the community cares about a place.

"Criminal activity will not be tolerated in these spaces," she said.

Even if you're not convinced that reducing crime counts as improving health, federal health officials seem invested. The mapping project is partly funded by the National Institutes of Health.

Before and after the "green" treatment 

Paine's Park, near the Art Museum, is one of places that has gotten Philly's "green" treatment.

Before it was transformed, there was lots of bare earth and construction debris piled up. Now there is porous pavement and lots of vegetation planted throughout the site.

One 25-foot trench called a bioswale is sloped-to let rainwater slowly soak into the ground. Trees and shrubs are planted at the bottom of the trench so their leaves and roots can intercept rainwater.

Kondo presented her work this week at a gathering for the Meetup group GeoPhilly. The group includes almost 400 map enthusiasts—including academics, students and programmers.

Hoping to reach the hands of policymakers 

Organizer Sarah Cordivano said she and others want to use geographic data to hack civic problems.

"The open data movement, which is a movement that encourages cities to release a lot of their data sets, gives researchers, citizens--data geeks like myself--the opportunity to dig into these data sets," Cordivano said. "It can be a fun and easy way to try to put the pieces together to solve problems."

The members have all sorts of interests, but Tuesday they got together for pizza and to talk about public health.

For one project in Philadelphia, Cordivano helped map the cost and time it takes to navigate the city when you've just had a baby--but don't have a car.

So who would use a map like that? "Well, hopefully policymakers," Cordivano said.

"There's a lot of appointments that women need to go to after they give birth, and if they already have a few kids, and don't have child care, it is very prohibitive for them to attend all those appointments, so it's easy for them to skip the appointments, which certainly has negative effects on the wellbeing of their baby," she said.

Maps might help city officials decide where to open a new health clinic—or suggest that the local food-stamp office should be located under the same roof as the neighborhood day care center.

Civic hackers try to get their maps into the hands of decision makers. Or often they're a tool to lobby for health resources in one community or another.

Lots of maps lump us all together with everyone else in our home zip code or census tract, but that thinking is evolving.

Now when mapmakers think about health, Cordivano says they try to consider all the places people spend time.

"Throughout the day, you might take a SEPTA bus to work, you might walk to the grocery store, or drive to the pharmacy, and all of those experiences effect you. And it's a little bit more complex than simply saying I live in this area or I live in this neighborhood," she said.