A Difference-In-Differences Study of the Effects of a New Abandoned Building Remediation Strategy on Safety.

Vacant and abandoned buildings pose significant challenges to the health and safety of communities. In 2011 the City of Philadelphia began enforcing a Doors and Windows Ordinance that required property owners of abandoned buildings to install working doors and windows in all structural openings or face significant fines. We tested the effects of the new ordinance on the occurrence of crime surrounding abandoned buildings from January 2011 to April 2013 using a difference-in-differences approach. We used Poisson regression models to compare differences in pre- and post-treatment measures of crime for buildings that were remediated as a result of the ordinance (n = 676) or permitted for renovation (n = 241), and randomly-matched control buildings that were not remediated (n = 676) or permitted for renovation (n = 964), while also controlling for sociodemographic and other confounders measured around each building. Building remediations were significantly associated with citywide reductions in overall crimes, total assaults, gun assaults and nuisance crimes (p < 0.001). Building remediations were also significantly associated with reductions in violent gun crimes in one city section (p < 0.01). At the same time, some significant increases were seen in narcotics sales and possession and property crimes around remediated buildings (p < 0.001). Building renovation permits were significantly associated with reductions in all crime classifications across multiple city sections (p < 0.001). We found no significant spatial displacement effects. Doors and windows remediation offers a relatively low-cost method of reducing certain crimes in and around abandoned buildings. Cities with an abundance of decaying and abandoned housing stock might consider some form of this structural change to their built environments as one strategy to enhance public safety.