A difference-in-differences analysis of health, safety, and greening vacant urban space.

TitleA difference-in-differences analysis of health, safety, and greening vacant urban space.
Publication TypeJournal Article
Year of Publication2011
AuthorsBranas CC, Cheney RA, MacDonald JM, Tam VW, Jackson TD, Ten Have TR
JournalAm J Epidemiol
Volume174
Issue11
Pagination1296-306
Date Published2011 Dec 1
ISSN1476-6256
KeywordsCities, Crime, Exercise, Health Status, Humans, Hypercholesterolemia, Hypertension, Linear Models, Philadelphia, Public Health, Stress, Psychological
Abstract

Greening of vacant urban land may affect health and safety. The authors conducted a decade-long difference-in-differences analysis of the impact of a vacant lot greening program in Philadelphia, Pennsylvania, on health and safety outcomes. "Before" and "after" outcome differences among treated vacant lots were compared with matched groups of control vacant lots that were eligible but did not receive treatment. Control lots from 2 eligibility pools were randomly selected and matched to treated lots at a 3:1 ratio by city section. Random-effects regression models were fitted, along with alternative models and robustness checks. Across 4 sections of Philadelphia, 4,436 vacant lots totaling over 7.8 million square feet (about 725,000 m(2)) were greened from 1999 to 2008. Regression-adjusted estimates showed that vacant lot greening was associated with consistent reductions in gun assaults across all 4 sections of the city (P < 0.001) and consistent reductions in vandalism in 1 section of the city (P < 0.001). Regression-adjusted estimates also showed that vacant lot greening was associated with residents' reporting less stress and more exercise in select sections of the city (P < 0.01). Once greened, vacant lots may reduce certain crimes and promote some aspects of health. Limitations of the current study are discussed. Community-based trials are warranted to further test these findings.

DOI10.1093/aje/kwr273
Alternate JournalAm. J. Epidemiol.
PubMed ID22079788