Impact of green infrastructure installation on surrounding health and safety

Context: In 2007, the U.S. EPA implemented regulations encouraging municipal use of green stormwater infrastructure (GSI) to meet federal water quality standards. GSI has been promoted as having economic and health benefits in addition to environmental benefits. However, limited evidence exists in support of GSI health and safety impacts.

Methods: We conducted a difference-in-differences analysis of the effects of green infrastructure installments on health and safety outcomes from 2000 to 2011 in Philadelphia, PA. We used mixed-effects regression models to compare differences in pre- and post-treatment measures of outcomes for randomly matched treatment sites (n=52) and control sites (n=186) within multiple geographic extents surrounding GSI sites. Safety outcomes included counts of homicides, aggravated assaults, thefts, burglaries, disorderly conduct, illegal dumping, public drunkenness, robberies, vandalism, and narcotics trafficking. Health outcomes included high blood pressure, cholesterol and stress levels.

Results: Regression-adjusted models showed consistent and statistically significant reductions in narcotics-possession (18-27% less) within one-sixteenth, one-quarter, half-mile (<0.001) and one-eighth mile (<0.01) distances from treatment sites as well as at the Census tract level (<0.01). Narcotics-manufacture was also significantly reduced at one-quarter (<0.001), and half-mile (<0.01) distances. Non-significant reductions in homicides, assaults, burglaries, thefts, public drunkenness and narcotics sales were associated with GSI installation in at least one geographic extent analyzed.

Conclusions: Health and safety considerations, such as reductions in certain crimes, should be included in future assessments of green infrastructure programs. Subsequent studies are warranted to assess for mechanisms of this association.