Matthew Browning , Dexter H Locke , Cecil Konijnendijk, S M Labib, Alessandro Rigolon, Ray Yeager, Mondira Bardhan, Adam Berland, Payam Dadvand, Marco Helbich, Fu Li, Hanson Li, Peter James, Jochem Klompmaker, Aaron Reuben, Lara Roman, Wei-Lun Tsai, Muhammad Mainuddin Patwary , Jarlath O'Neil-Dunne, Alessandro Ossola, Ruoyu Wang, Boyi Yang, Li Yi, Jinguang Zhang, Mark Nieuwenhuijsen

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 meters of a high-quality green space. Implementing this demands thorough measurement, monitoring, and evaluation methods. Seven data and processes exist to assess these components, including vegetation indices, street level analyses, tree inventories, questionnaires, window view analyses, land cover maps, and green space maps. Our panel of expert’s consensus recommends surveys and window-view analyses for the '3', high-resolution land cover maps for the '30', and green space maps with network analyses for the '300'. 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.