Penn study finds PHS vacant land program reduces assaults and vandalism

By the PlanPhilly staff

The Pennsylvania Horticultural Society program that cleans and greens vacant land results in significant reductions in gun assaults across most of Philadelphia and fewer instances of vandalism in one section of the city, according to findings of a University of Pennsylvania study released online in the American Journal of Epidemiology this week.

Greening vacant land was also associated with residents reporting less stress and engaging in more exercise.

The Penn team was led by senior author Charles C. Branas, PhD, associate professor of epidemiology at the Perelman School of Medicine. The study, funded in part by the U.S. Centers for Disease Control and the National Institutes of Health, involved a decade-long comparison of vacant lots and improved vacant lots.

“Improving the places where people live, work and play holds great promise for changing health and safety,” Branas said. “Greening vacant lots is a low-cost, high-value approach which may prevent certain crimes and encourage healthy activity for more people for longer periods of time than many other approaches.”

“The study by Dr. Branas and his team is fantastic news for the Pennsylvania Horticultural Society, which in partnership with the City of Philadelphia has reclaimed thousands of blighted vacant lots,” said PHS President Drew Becher. “We have known that greening these lots has helped transform neighborhoods in various ways. The Penn findings reveal other significant, direct impacts of this program on the lives of residents.”

PHS began a program to green vacant lots – abandoned open spaces with no buildings – in Philadelphia in 1999. The work involved removing trash and debris, grading the land, planting grass and trees to create a park-like setting, and installing low wooden post-and-rail fences around each lot to show that it was cared for and to deter illegal dumping. Several times a year, PHS returned to each greened lot to coordinate basic maintenance such as mowing the grass, tending the trees and repairing the fences.

Nearly 4,500 vacant lots totaling more than 7.8 million square feet were greened by the PHS from 1999-2008, in coordination with the city’s Office of Housing and Community Development.

“Dr. Branas’ study adds to the growing body of evidence that cleaned and greened lots are important elements in a revitalized community,” said Mayor Michael Nutter. “The city’s partnership with PHS enhances health and safety, in addition to creating jobs and increasing property values. Now we have scientific proof of this collaboration.”

Branas and his team analyzed the impact of this program using a statistical design that considered various health and safety outcomes and numerous other factors occurring on and around vacant lots, before and after they were treated, as compared to vacant lots that were not greened over the same period.

Untreated lots were randomly selected and matched to treated lots by section of the city, within four of the five sections of Philadelphia. The Northeast section was excluded because only a handful of vacant lots were greened there. Vacant lots eligible to serve as matched controls included only those that had never been greened from 1999 to 2008, but that could have been chosen by the PHS for greening.

A master database of over 50,000 vacant lots in Philadelphia from 1999-2008 was assembled from Philadelphia Bureau of Revision of Taxes and Department of Licenses & Inspections records. The database was separated into lots greened by PHS and lots that were not greened.

The Philadelphia Police Department provided the dates and locations for several types of crimes and arrests from 1999 to 2008: aggravated assaults, aggravated assaults with guns, robberies, robberies with guns, narcotics sales and possession, burglaries, thefts, vandalism and criminal mischief, disorderly conduct, public drunkenness, and illegal dumping. The Philadelphia Health Management Corporation provided community-level health data from the Southeastern Pennsylvania Household Health Survey.

“This is one of the first rigorous studies to show that reducing physical decay in neighborhoods -through such efforts as cleaning up vacant lots – reduces public safety crimes, demonstrating that healthier places are safer places,” said co-author John MacDonald, PhD, chair of Penn’s Criminology Department. “Public policies that promote active living can also enhance personal safety.”

Vacant lot greening was associated with significant reductions in gun assaults across all four sections of Philadelphia in the study and significant reductions in vandalism in one section of the city.

Greening was also associated with residents reporting significantly less stress and more exercise in certain sections of Philadelphia.

Because newly greened vacant lots may serve as safe havens, residents may have felt less stress or may have seen greater outdoor opportunities for exercise in a cleaner, more attractive and safer environment, the authors said. Even though these findings pertaining to stress and exercise only applied to certain sections of the city, they have potentially important implications for the future study of urban vacant lot greening as a tool to enhance health.

“Violent crime may have simply been discouraged in the presence of greened and tended vacant lots that signaled someone in the community cared and was watching over the space in question,” Branas said. “The effect of greening may have also been more tangible, especially for gun assaults, where vacant lots may have been a haven, storage ground, or disposal point for illegal guns.

Because the penalty of being caught with an illegal gun is high, criminals may hide their guns in abandoned vacant lots.”

Surprisingly, acts of disorderly conduct – a catch-all category encompassing various violations and nuisances – increased after the greening of vacant lots. A greened lot may serve as a new opportunity for community gatherings, bringing large groups of people together and increasing the opportunity for crowd-based nuisance crimes such as disorderly conduct, the researchers said. Community interest in maintaining a newly greened lot may have also increased calls to police and arrests for disorderly conduct.

“The large number of vacant lots we studied and the design of our analysis make this study some of the strongest evidence to date that greening vacant urban land is a promising approach to improving health and safety,” Branas said. “As with all studies, it’s not the final word, and we are now moving forward with a randomized trial of vacant lot greening to even more thoroughly investigate. Philadelphia, like many cities, still has tens of thousands of vacant and abandoned lots to support such a study.”

Co-authors, all from Penn, are Rose A. Cheney, PhD, Department of Surgery; Vicky W. Tam, Cartographic Modeling Laboratory; Tara D. Jackson, PhD, Cartographic Modeling Laboratory; and Thomas R. Ten Have, PhD, MPH, Department of Biostatistics and Epidemiology.

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