Deliver Benefits to the Public

New research shows power of cleaning/greening neighborhoods in reducing depression

Graphic: Map showing dots representative of lots studied. Three colors of dots representing greening intervention, trash clean-up intervention, and no intervention.
This map shows the distribution of randomly selected study vacant lots across 3 groups of the trial: the greening intervention, the trash cleanup intervention, and no intervention. The distribution of vacant lots shown is representative of those in the study, although for the purposes of confidentiality are not the locations of actual study lots. Graphic courtesy "Effect of Greening Vacant Land on Mental Health of Community-Dwelling Adults" study.


—Michelle Kondo, a research social scientist with the Northern Research Station’s Philadelphia Field Station, is a co-author of a new study that is the first citywide cluster randomized trial that tests the effects of inexpensive, standardized and reproducible vacant land remediation interventions—namely greening and trash cleanup—on health and safety. The study, “Effect of Greening Vacant Land on Mental Health of Community-Dwelling Adults,” is available online.

The findings have implications for cities throughout the United States, where 15 percent of land is deemed vacant. Previous studies have demonstrated a correlation between neighborhood conditions such as vacant property, uncollected trash, and lack of sidewalks and parks with depression. This study, however, is the first where a research team studied the problem as they would a new drug—with a randomized controlled trial that measured the mental health of residents before and after any work was done.

Scientists assigned 110 vacant lot clusters in Philadelphia, Penn., for a total of 541 vacant lots, to one of three study groups: the greening intervention clusters, the trash cleanup intervention, or the control group, where no intervention occurred. Eighteen months after greening projects began, 342 residents in neighborhoods that were at or below-poverty reported improvement. Of those living within a quarter-mile of an intervention area, 41 percent of the people included in the study reported feeling significantly less depressed, and self-reported poor mental health showed a reduction of nearly 63 percent.

Photo series: photos show vacant, trash-filled lots, then work being done with wheelbarrows, then final, green, fenced lot.
Images show blighted pre-period conditions and remediated post-period restorations. A, The image shows the grass seeding method used to rapidly complete the treatment process. B, The after image shows the low wooden perimeter fence. Vacant lots shown here are representative of those in the study, although for purposes of confidentiality are not actual study lots. Photos courtesy "Effect of Greening Vacant Land on Mental Health of Community-Dwelling Adults" study.

The study was recently published in the journal JAMA Network Open. Kondo and her co-authors, including lead author Eugenia C. South of the University of Pennsylvania’s Perelman School of Medicine, have contributed to a growing body of research demonstrating the mental health benefits of urban green space. Cleaning up vacant and dilapidated areas can be an effective and comparatively low-cost tool in improving mental health, costing about $1,600 per vacant lot restoration and just $180 per year to maintain.