New Peer-Reviewed Study Quantifies Urban Green Space as a $374-Per-Citizen Annual Hedge Against Rising Medical Spending
San Francisco, Calif. – November 26, 2025 Urban planners looking for evidence-based ways to slow double-digit healthcare inflation have fresh data to present to city councils this budget season. A longitudinal study published today in Environment International shows that residents living in the city’s leafiest census blocks generated mean annual medical costs that were $374 lower per person than demographically similar residents on the least-green blocks—a difference that, if scaled nationally, implies potential system-wide savings in the billions of dollars each year.
Researchers at Kaiser Permanente Northern California and Clemson University followed 5.1 million health-plan members for up to 13 years, pairing individual claims data with satellite-derived vegetation indices measured at 250 m, 500 m, and 1 km radii around each member’s home address. After adjusting for age, sex, race/ethnicity, income, education, housing density, air quality, and neighborhood socioeconomic status, the inverse relationship between greenery and cost persisted across every cost category except emergency-room spending.
“We approached the data skeptically, thinking socioeconomic advantage might explain the pattern,” said lead author Stephen K. Van Den Eeden, Ph.D., a principal investigator at Kaiser Permanente’s Division of Research. “Even after throwing every covariate we had into the model, the green-space signal remained, suggesting biologic and behavioral pathways—stress reduction, physical activity, and improved air quality—are translating into measurable fiscal relief for integrated health systems like ours.”
A separate 2024 within-person analysis of 129,000 movers—released earlier this year—found that outpatient costs fell by roughly $89 annually when individuals relocated to blocks that jumped from the lowest to the highest decile of greenness, an effect driven primarily by women and adults aged 18-44.
While total spending showed no statistically significant change, the outpatient dip corroborates the earlier $374 cross-sectional figure and hints that preventive primary-care utilization may be the first budget line to benefit from neighborhood greening projects.
Market data underscore why city budget directors are taking notice. U.S. municipal governments shoulder approximately 14 percent of the nation’s $4.5 trillion medical bill through employee coverage, public-hospital subsidies, and uncompensated-care pools. Using the study’s midpoint estimate, a city of 500,000 residents that increases average NDVI greenness by one decile could anticipate annual healthcare savings on the order of $90 million—enough to service roughly $1.2 billion in green-infrastructure bonds at current muni rates, according to back-of-the-envelope calculations by the non-profit Trust for Public Land.
“For decades we marketed parks as quality-of-life amenities; now we can price them as cost-containment tools,” observed Matthew H.E.M. Browning, Ph.D., associate professor at Clemson’s Department of Parks, Recreation and Tourism Management and co-author on both studies. “This evidence base gives finance officers a defensible line item when they integrate tree canopy, trails, and green roofs into capital-improvement plans.”
The findings arrive as Congress debates reauthorization of the Inpatient Prospective Payment System and states scramble to meet their share of the $2.8 billion in federal Urban and Community Forestry grants allocated under last year’s Inflation Reduction Act. City applicants that embed healthcare-cost offsets in their grant narratives—citing peer-reviewed ROI figures—score higher on cost-effectiveness criteria, according to program guidance released by the U.S. Forest Service last month.
About the Company
Kaiser Permanente is America’s largest integrated, nonprofit health system, serving 12.6 million members and operating 39 hospitals and 734 medical offices. The Division of Research conducts federally funded, population-based studies aimed at improving prevention, care delivery, and health equity.
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