City nature counts: forest bathing without the forest

Most of the people I talk to in New York assume nature means leaving the city. The research says otherwise, and it says it in numbers. The green between buildings, a leafy block, a small park, a river path, shows up in the body.

The studies below were run in Copenhagen, in a lab in Illinois, in three English towns, and across five million Californians. None of them involved a wilderness. They involved the kind of green that exists between buildings.

The short version

• Cities restore too. In Copenhagen, a historic downtown calmed the body about as well as a forest did. Only the forest lifted mood.
• Street tree cover helped men recover from stress, most of all up to about a quarter of the street in canopy. A fifth of a neighborhood under vegetation is a threshold.
• Greener addresses went with lower healthcare costs across five million Californians.

What the research says

Start with the study whose title says it all: "It is not all bad for the grey city." A team at the University of Copenhagen took 51 female students to a forest and to a historic downtown on separate days and measured heart rate, blood pressure and mood. Both settings calmed the body more than the office did, but only the forest walk improved mood. The city walk left mood where it was, and the forest was rated the more restful place. What surprised the authors, enough to put it in the title, was how well the city did on the body measures.

Street trees seem to work in doses. At the University of Illinois, 160 people were stressed with a public-speaking task, then shown a 3D video of a residential street with anywhere between 2 and 62 percent tree cover. For men, recovery improved as tree cover rose to about a quarter of the street, flattened between a quarter and a third, and was slower again above that. For women, the line was flat, which the authors could not fully explain. The takeaway is that the canopy on an ordinary street shows up in the body, and that more is not always better.

Neighborhood green has thresholds too. In three English towns, living in a neighborhood with more than roughly a fifth to a third of its area under vegetation went with lower depression, anxiety and stress. Afternoon bird numbers had a similar link.

The effect even shows up in healthcare spending. Researchers at Kaiser Permanente looked at five million members of their California health system alongside the green cover around each home. People in the greenest areas had lower direct healthcare costs than those in the least green, by several hundred dollars per person per year, after allowing for income, age and other factors. Green cover was measured at the neighborhood scale, the kind visible from a window.

Ask people what green space does for them and the answers line up. A 2023 synthesis of interview studies found the recurring themes were escape from demands, a sense of connection, calm, and a place to think. Nobody was describing wilderness. Most were describing a local park.

And it works on an ordinary Tuesday. When the University of Michigan let 36 city dwellers choose their own natural spot for at least 10 minutes, three times a week, the stress hormone cortisol in their saliva fell, with the best return per minute between 20 and 30 minutes. The spots were whatever felt natural to each person within their city: a park, a yard, a tree-lined block.

How to try it in New York

• Use the streets you already walk. A block with mature trees is a dose. Route your commute through the greener one.
• Find the parks that feel like forest. Inwood Hill Park holds Manhattan's last natural forest. The North Woods and the Ramble in Central Park were designed to feel remote. Prospect Park's Ravine does the same in Brooklyn.
• Add water when you can. The Hudson, the East River, the Reservoir. Several studies find water adds to the effect.
• Look for birds. The afternoon bird count in the English study predicted lower stress on its own. Morning is easier for hearing them.

If you don't walk

The Copenhagen and Michigan results came from people out in the green, and a walk is what takes you to the better parts of it. If walking is out, two of the studies above measured where people live and nothing about what they did. A window that looks onto trees, a fire escape with plants, a bench on a leafy block: each is the kind of exposure the healthcare-cost and neighborhood studies counted. It is a smaller dose, and it still counts.

Questions people ask

Does a small park work as well as a big one?

Size mattered less than greenness and visit length in the studies above. A small park you visit for 30 minutes beats a large one you never reach.

What about noise and traffic?

Traffic noise likely cuts the benefit, which is one reason I expect the interior of a large park to beat its edge. Choose the path furthest from the road.

Is the benefit only for people who like nature?

The cortisol and street-tree studies did not screen for nature preference. The cortisol drop appeared across the group; in the street-tree study the effect showed only in men.

Manhattan's Last Forest is a 70-minute walk through Inwood Hill Park, the one place on the island where the trees predate the grid.

On the science: every study here is real. The underlined phrases link straight to the papers, and the full list is below. The summaries and takeaways are my own reading, simplified to be useful rather than complete.