by CC Branas, RA Cheney, JM MacDonald, VW Tam, TD Jackson, TR Ten Have
American Journal of Epidemiology 174(11):1296-13062011
Beginning in 1999, the Pennsylvania Horticultural Society (PHS) began a program to improve vacant lots around Philadelphia with vegetation. Trash was removed, trees and grass were planted, and perimeter boundaries were marked to indicate care. The sites were visited several times a year for mowing and maintenance. This study compared the greened lots with control lots that were left vacant to determine if there were effects on a variety of health and safety outcomes over a period of 10 years. Crime data were collected from the Philadelphia Police Department, health data (stress, high cholesterol, high blood pressure, exercise, overall health) from the Southeastern Pennsylvania Household Health Survey, and demographic information from the US Census Bureau. The results were clearest for gun assaults, which were significantly lower in the areas around greened lots than around control lots. In some areas of the city, there were also reductions in vandalism and criminal mischief as well as reported reductions in stress and increased activity levels. Limitations of the study methodology are presented.