Measuring the 3-30-300 rule to help cities meet nature access thresholds.

The 3-30-300 rule offers benchmarks for cities to promote equitable nature access. It dictates that individuals should see three trees from their dwelling, have 30 % tree canopy in their neighborhood, and live within 300 m of a high-quality green space. Implementing this demands thorough measurement, monitoring, and evaluation methods, yet little guidance is currently available to pursue these actions. To overcome this gap, we employed an expert-based consensus approach to review the available ways to measure 3-30-300 as well as each measure's strengths and weaknesses. We described seven relevant data and processes: vegetation indices, street level analyses, tree inventories, questionnaires, window view analyses, land cover maps, and green space maps. Based on the reviewed strengths and weaknesses of each measure, we presented a suitability matrix to link recommended measures with each component of the rule. These recommendations included surveys and window-view analyses for the '3 component', high-resolution land cover maps for the '30 component', and green space maps with network analyses for the '300 component'. These methods, responsive to local situations and resources, not only implement the 3-30-300 rule but foster broader dialogue on local desires and requirements. Consequently, these techniques can guide strategic investments in urban greening for health, equity, biodiversity, and climate adaptation.

Vacant Building Removals Associated with Relative Reductions in Violent and Property Crimes in Baltimore, MD 2014-2019.

Vacant and abandoned buildings are common features in many post-industrial US cities, and are consistent predictors of violence. Demolition programs are regularly employed as an urban land use policy to stabilize housing markets and mitigate public health problems including violence. The objective of this research was to examine the effect of vacant building removals on violent and property crimes in Baltimore, MD from 2014 to 2019. We conducted a difference-in-differences analysis using spatio-temporal Bayesian mixed models on six crime types on block faces with and without building removals, before compared with after removal. There were significant reductions in total, violent crimes (with and without assaults), thefts, and burglaries on block faces with building removals relative to their controls. Total crimes decreased 1.4% per mi2 (CrI: 0.5 - 2.3%), which translates to a relative reduction ~ 2.6 total crimes per mi2 per year. The largest relative decreases in crime were found among assaults (4.9%; CrI: 3.4 - 6.3%) and violent crimes (3.0%; CrI: 1.9 - 4.1%). Building removals were associated with relative reductions in crime in Baltimore City. The relative reductions in crime, at building removals compared to at control vacant lots, were found among assaults and violent crimes, the crimes of greatest public health concern. Building removals provide co-benefits to their communities, and may be considered part of a crime reduction strategy compatible with other approaches. A systematic effort to understand the role of care for remaining vacant lots could further inform our findings, and efforts to further decrease violence and improve community health.