Vacant lot remediation and firearm violence – A meta-analysis and benefit-to-cost evaluation

Abstract

Our objectives were to synthesize the early evidence regarding the effect of city-wide vacant-lot remediation programs on firearm violence and to determine what proportion of remediation costs are recovered from reducing firearm violence. Building on our scoping review, we conducted a meta-analysis of before-and-after studies with control groups. We then assumed three hypothetical cities of small, medium, and large populations and performed a probabilistic benefit-to-cost analysis over 30 years.Eight studies met our eligibility criteria. Interventions included mowing (n = 3), greening (n = 5), and gardening (n = 2), with two studies examining two different interventions. The pooled effect size did not show reduction in firearm violence by mowing vacant lots. However, greening and gardening interventions reduced firearm violence by 5.84% (95% CI: 7.89–3.79%) and 5.34% (95% CI: 7.74–2.93%) respectively. Greening programs were the most cost-effective intervention and cost savings from reducing firearm violence can recover an estimated 8.17% (95% CI: 8.11–8.23%), 10.20% (95% CI: 10.12–10.28%), and 21.06% (95% CI: 20.90–21.23%) of intervention expenses, equating to the net annual per capita costs of $64.53 (95% CI: $64.09–$64.96), $51.88 (95% CI: $51.53–$52.25), and $30.97 (95% CI: $30.73–$31.22) in the small, medium, and large cities respectively.While vacant lot remediation programs can play a robust role in controlling firearm violence at lower per capita costs than law enforcement polices, cost savings from reducing firearm crimes by itself does not recover all program costs. However, health and environmental benefits of such programs can offset the greening and maintenance costs.