Renovating abandoned homes reduces rates of gun violence, Penn study finds

Hammers and screwdrivers can be effective tools in preventing gun violence.

That’s the conclusion of a new study by researchers at the University of Pennsylvania, who measured crime rates near clusters of abandoned Philadelphia homes with new doors, windows and other upgrades.

Previous research has shown that crime decreases when vacant homes are repaired, but it was unclear whether the connection between these two things was more than a coincidence. To determine whether home repairs actually prevent crime, Penn’s team approached the question with the same rigorous approach doctors use to study a new drug: with a randomized controlled trial.

The findings leave little doubt, said lead author Eugenia C. South, assistant professor of emergency medicine at Penn’s Perelman School of Medicine.

Gun crime increased across the city over the study period, but there was less of an increase in neighborhood blocks surrounding renovated homes, compared to those where abandoned homes were left alone, South and his co-authors reported in JAMA Internal Medicine.

The repairs likely helped in two ways, she said: by healing the social fabric of the neighborhood and by eliminating possible hiding places for guns.

“The magnified view of this is simply that the places and spaces around us are important to our health and well-being,” she said.

The findings come amid an ongoing wave of gun violence in America’s poorest major city, where officials have spent millions on anti-violence programs, in some cases with limited evidence of their effectiveness .

But in at least one case, a city-funded effort has proven effective in deterring crime at relatively low cost: an ongoing program to clean up and replant vacant lots. Similarly, in the new Penn study, home repairs required a modest outlay, averaging $5,900 per property.

The real-world experiment involved 63 clusters of randomly selected abandoned houses across the city, each consisting of one “index” house and two to four others within a ⅛ mile radius. Housing the clusters were then divided into three groups: one to receive repairs, weeding and garbage cleaning; another for weeding and garbage collection only; and a third to be left alone.

Repairs included the installation of new doors and windows in the front and sides of each house, in some cases also the repair of a deteriorated facade. Workers performed follow-up maintenance on each property every 2.5 months, and in 10 cases they reinstalled windows and doors that had been stolen.

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The researchers then compared crime rates in the 18 months before and after the treatments, starting in January 2017. While crime rates increased in areas surrounding the three types of clusters, they increased less near homes repaired — in fact, that’s a real reduction in crime, said Columbia University epidemiology professor Charles C. Branas, who worked with Penn’s team.

In the areas immediately surrounding the repaired homes, weapons violations were 8.4% lower than they would have been without the repairs, and gun assaults were 13.1% lower. That amounted to roughly a reduction of one or two gun crimes per square mile each month, said Penn criminology professor John MacDonald, another study author.

Home repairs were also associated with fewer shootings, although the statistical weight of this finding is less clear. (In clusters that only got weeding and garbage collection, no significant change in crime rates occurred.)

The research clearly demonstrates the impact of reparations on crime rates, however limited, Branas said.

Had the authors simply tracked crime rates near homes that were already in need of repair, they could not have ruled out that any drop in crime rates was the result of other factors – say, a vigilant block captain or a neighboring store owner who hired a security guard.

Instead, by randomly selecting clusters of homes that received the treatment, the authors were confident that any impact on crime was occurring as a direct result, Branas said.

“It allowed us to really know whether it was working or not,” he said.

Exactly how reparations helped is less clear, but one likely reason is that criminals had fewer places to conduct illicit activity, he said. Usually the broken doors and windows of abandoned houses are covered with plywood, which can easily be peeled off, especially once softened by the rain.

“You can pick it up pretty quietly and get behind it,” he said.

Another key is that physical repairs enable healthy social interaction, said South, faculty director at Penn’s Urban Health Lab. When dilapidated homes are sealed up and remediated, neighbors are more likely to come out and connect with each other, potentially working together to stay out of trouble, previous research has found.

“Then they can get together with their neighbors to work out issues like the trash isn’t being picked up or the local kid stayed out too late,” she said. “Some behaviors just aren’t tolerated in some places.”

The researchers also checked whether the repairs simply caused the criminals to remove their business from a block or two, and found no such pattern. The treatment seemed to have a net positive effect.

Although the impact of the repairs was modest, the results were encouraging, said Thomas Abt, a criminology researcher at the University of Maryland College Park who was not involved in the project.

“I think we now know it works, but we also know it doesn’t work well enough to be the only strategy,” he said. “The bottom line is that paying attention to the physical environment in which crime occurs is an important piece of the overall puzzle.”

The repair work was done by the Philadelphia Redevelopment Authority, funded by a grant from the National Institutes of Health.

Asked about the possibility of renovating more abandoned houses, Mayor Jim Kenney’s office noted that the city is already spending heavily on such projects. In the fiscal year that ended June 30, the city spent $5.9 million to clean up and seal 159 abandoned homes; demolish 43 others; and servicing thousands of vacant lots, spokeswoman Sarah Peterson said.

“We are grateful for the additional understanding of the benefits of these programs,” she said.

Should the program be expanded, there are plenty of additional candidates to fix – with an estimated 10,000 abandoned homes in Philadelphia, and even more vacant lots.