SignificanceBlighted and vacant urban land is a widespread and potentially risky environmental condition encountered by millions of people every day. About 15% of the land in US cities is deemed vacant or abandoned, translating into an area roughly the size of Switzerland: over 3 million hectares of otherwise beneficial spaces remain neglected. Urban residents, especially in low-income neighborhoods, point to these spaces as primary threats to their health and safety. Cities continue to seek meaningful, evidence-based interventions for remediating vacant land. Standardized processes for the restoration of vacant urban land were experimentally tested on a citywide scale and found to significantly reduce gun violence, crime, and fear.

Key Points Question Does the greening of vacant urban land reduce self-reported poor mental health in community-dwelling adults? Findings In this cluster randomized trial of urban greening and mental health, 110 randomly sampled vacant lot clusters were randomly assigned to 3 study groups. Among 342 participants included in the analysis, feeling depressed significantly decreased by 41.5% and self-reported poor mental health showed a reduction of 62.8% for those living near greened vacant lots compared with control participants. Meaning The remediation of vacant and dilapidated physical environments, particularly in resource-limited urban settings, can be an important tool for communities to address mental health problems, alongside other patient-level treatments.

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Objectives. To determine if blight remediation of abandoned buildings and vacant lots can be a cost-beneficial solution to firearm violence in US cities.Methods. We performed quasi-experimental analyses of the impacts and economic returns on investment of urban blight remediation programs involving 5112 abandoned buildings and vacant lots on the occurrence of firearm and nonfirearm violence in Philadelphia, Pennsylvania, from 1999 to 2013. We adjusted before-after percent changes and returns on investment in treated versus control groups for sociodemographic factors.Results. Abandoned building remediation significantly reduced firearm violence -39% (95% confidence interval [CI] = -28%, -50%; P < .05) as did vacant lot remediation (-4.6%; 95% CI = -4.2%, -5.0%; P < .001). Neither program significantly affected nonfirearm violence. Respectively, taxpayer and societal returns on investment for the prevention of firearm violence were $5 and $79 for every dollar spent on abandoned building remediation and $26 and $333 for every dollar spent on vacant lot remediation.Conclusions. Only a modicum of attention has been paid to intervening upon the context within which firearm violence occurs and the urban environments in which it thrives. It is now commonly accepted that changing the context within which health problems occur is a leading opportunity for high-impact change, often better than focusing on individuals and lifestyles. [13][14][15][16][17] This may also apply to firearm violence-individuals who are simply instructed to adhere to safety practices are unlikely to be successful if the unsafe context within which they find themselves day after day does not permit it. Directly changing the contexts and environments that promote firearm violence is a potentially potent solution to explore in reducing the persistent problem of firearm violence in the United States. Such contextual changes may take the form of actual, in-situ changes to the environments themselves, an approach that may be more politically feasible, economically viable, and have a greater probability of widespread implementation. 13,18 Cities in the United States experience a heavily disproportionate burden of the nation's interpersonal firearm violence. 19Urban shootings are concentrated in neighborhoods stricken by poverty and neglect, and a growing body of scientific evidence suggests that blighted neighborhood environments are strongly tied to firearm violence in US cities. 9,[20][21][22][23][24][25] It is very possible that directly treating aspects of these blighted environments in inexpensive ways could produce lasting reductions in urban firearm violence. However, to our knowledge, no research has yet investigated the cost benefits, Medicine, Philadelphia, PA 19104-6021 (e-mail: cbranas@upenn.edu). Reprints can be ordered at http://www.ajph.org by clicking the "Reprints" link.