A new study has been released on the association between residential green cover and healthcare costs. Published in Environment International March of 2022, the study analyzed health care costs of over 5 million members of Kaiser Permanente Northern California from 2003 to 2015.
The researchers observed a significant inverse association between higher levels of green cover and lower direct healthcare costs, including the finding that individuals living near the most green space had adjusted health care costs of $374 per person per year less than those living near the least green space. Those in the highest decile of residential green cover were more likely to be white, older, male, and have higher education and income levels. Even after adjusting for sociodemographic and socioeconomic factors, the findings were robust.
To quantify the green space, the researchers utilized the Normalized Differentiation Vegetation Index (NDVI) satellite data. NDVI data “reflects the greenness found in satellite images of land cover and has been commonly used in the geospatial assessment of vegetation presence and viability as well as in the study of green space and human health.” Healthcare costs were obtained from the internal Cost Management Information System which compiles data from health service centers (hospitals, labs, etc.).
One key strength of this study is the size and diversity of the population where everyone shares the same health care system. Differentiations in health care access are greatly mitigated as all members of the Kaiser Permanente Northern California system have virtually equal access. Another strength is the variety of land use types and topographies over the large area (25,000 sq miles) covered. The green cover-cost relationship observed is not constrained to specific landscapes or geographic settings.
These findings support several previous studies on the health implications of green space and they exemplify not only the health benefit but also the economic impact of living near more green space. Researchers noted the existing body of literature that ties living near more green spaces to short and long term health benefits. High levels of green cover have been associated with better mental health, maternal-fetal outcomes, and fewer occurrences of cardiovascular disease, respiratory conditions, and mortality. This study supports nationwide efforts to incorporate green spaces into residential neighborhoods and urban greening.