A new study finds that counties with more forest and shrub land spend less per person on Medicare than those dominated by agriculture or urban vegetation.

"Counties with more forest and shrub land cover may hold both health and economic benefits for the elderly and disabled," researchers write. (Photo: Caspe Sparsoe/Unsplash)

Evidence that living near green spaces is good for your health has been steadily building over the past few years. Studies have linked access to nature to better heart health, better brain health, and greater all-around longevity.

But for some people, such findings don't fully sink in unless they come with a dollar number attached. New research might hold sway among that group—and among anyone else concerned about health-care costs in an aging society.

A new study finds that spending on Medicare-covered health services is significantly less in counties that are rich with forests and shrubbery.

"Counties with more forest and shrub land cover may hold both health and economic benefits for the elderly and disabled," writes a research team led by Douglas Becker of the University of Illinois–Urbana-Champaign. The group's study is published in the journal Urban Forestry and Urban Greening.

The researchers analyzed data on 3,086 of the 3,103 counties in the United States. They began with the National Land Cover Database, which measures the percentage of each county that consists of five types of vegetation: forest, shrub land, grassland, agriculture, and urban vegetation.

Then, after taking into account a number of factors known to influence health-care spending, such as age, race, and median household income, they compared those figures with Medicare per-capita spending in each county.

They found that each 1 percent of a county's land that was covered in forest was associated with lower Medicare spending of $4.32 per person per year.

"If you multiply that by the number of Medicare fee-for-service users in a county, and by the average forest cover ... it amounts to about $6 billion in reduced Medicare spending every year nationally," Becker said in announcing the findings.

He added that, when we factor in the effect of shrub lands, which are smaller but still significant, it increases the estimated average annual savings to $9 billion.

These effects were not uniform: They were greater in poorer counties, in which residents often have less access to high-quality health care. "Low-income communities are getting the biggest bang for their buck, because they probably have the most to gain," Becker said.

So how exactly do forests enhance human health? The researchers can't say for certain, but they cite several plausible theories.

"Trees may be central components of the stress-relieving natural landscapes in which our species evolved," they note. Besides their inherent restorative qualities, wooded areas "provide shade and more comfortable recreation and relaxation opportunities than other vegetated areas."

So you'll probably spend more time in nature, soaking up its psychological and health benefits, if you're lounging under a towering tree than baking in the mid-day sun.

Medicare, the researchers note, now composes "as much of the federal budget as defense spending." Planting more trees may be a viable way to limit the growth of those costs, even as we combat climate change. You might just spend less time at a hospital's branch office if you spend more time amid actual branches.