A health impact assessment of progress towards urban nature targets in the 96 C40 cities

Authors

Greta K. Martin, The George Washington University Milken Institute School of Public Health, Washington, DC, USA.
David Rojas-Rueda, Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA; Colorado School of Public Health, Colorado State University, Fort Collins, CO, USA.
Kelvin C. Fong, The George Washington University Milken Institute School of Public Health, Washington, DC, USA.
Marcia Pescador Jimenez, Boston University School of Public Health, Boston, MA, USA.
Patrick L. Kinney, Boston University School of Public Health, Boston, MA, USA.
Robert Canales, The George Washington University Milken Institute School of Public Health, Washington, DC, USA.
Susan C. Anenberg, The George Washington University Milken Institute School of Public Health, Washington, DC, USA. Electronic address: sanenberg@gwu.edu.

Document Type

Journal Article

Publication Date

4-1-2025

Journal

The Lancet. Planetary health

Volume

9

Issue

4

DOI

10.1016/S2542-5196(25)00053-1

Abstract

BACKGROUND: Urban greenspaces (eg, parks and trees) and blue spaces (eg, rivers and coasts) improve climate regulation and human health. In 2021, the mayors of 31 cities in the C40 Climate Leadership Group set 2030 targets for the percentage of urban greenspace and population with nearby natural (green or blue) space. We quantified annual all-cause mortality reductions from progress towards these targets for C40's 96 member cities. METHODS: We conducted a quantitative health impact assessment, testing three illustrative scenarios to increase urban greenspace: uniformly across space, in areas with the least nature, and in the most populated areas. We converted one percentage point progress towards each target in terms of the Normalized Difference Vegetation Index (NDVI) using previously published associations. We used mortality rate estimates from The Global Burden of Diseases, Injuries, and Risk Factors Study, population data from WorldPop, and a pooled hazard ratio of NDVI and all-cause mortality from an epidemiological meta-analysis. FINDINGS: Uniformly increasing greenspace by 1% yielded an estimated 96-city median of 1·77 (range 0·65-3·52, IQR 1·46-2·19) fewer annual premature deaths per 100 000 population; increasing the population percentage with nearby natural space yielded an estimated median of 0·56 (range 0·11-1·70, IQR 0·44-0·69) fewer annual premature deaths per 100 000 population. On average, compared with uniform increases, adding greenspace in the least natural areas provided 1·4-1·7 times (depending on the target) the health benefits, and adding greenspace in the most populated areas provided 2·7 times the health benefits. INTERPRETATION: The geographical distribution of greenspace expansion influences the magnitude of associated health benefits across varied urban contexts. Health benefits are largest when greenspace is added near population centres. FUNDING: Wellcome Trust, NASA, and The George Washington University.

APA Citation

Martin, Greta K.; Rojas-Rueda, David; Fong, Kelvin C.; Jimenez, Marcia Pescador; Kinney, Patrick L.; Canales, Robert; and Anenberg, Susan C., "A health impact assessment of progress towards urban nature targets in the 96 C40 cities" (2025). GW Authored Works. Paper 7114.
https://hsrc.himmelfarb.gwu.edu/gwhpubs/7114

Department

Environmental and Occupational Health