Forest Schools in Finland Boost Children's Immunity and Resilience

In Helsinki, on three mornings a week, twenty-one children between three and five years old lace up their boots and walk into the forest. They will spend the next seven hours there—all of it outdoors, regardless of weather. Rain, snow, wind below freezing: none of it matters. This is the Samoojat group at the Hopealaakso daycare, named after an old Finnish word meaning "people who feed themselves from the forest." For Juho Pietarila, whose four-year-old son Kauko joined the program recently, the change has been striking. Where mornings once meant tantrums and resistance, now his son grabs his backpack and says simply, "OK, let's go." The boy has learned something his father had to teach him: that there is no such thing as bad weather, only bad clothing.

The forest school model is not new to Scandinavia, but it is spreading. Every Monday, Wednesday, and Friday, the Samoojat children walk up to forty minutes through the woods to reach their camp. They eat lunch in an open-sided shelter, nap in a tent, and spend the rest of their time exploring—building bridges from branches, climbing trees, collecting berries, watching the shoreline. Three teachers in bright orange jackets supervise, but the children roam with a freedom that would alarm many parents in other countries. On Thursdays they venture to nearby sites around Helsinki. Fridays they stay at the daycare, mostly in the garden. Even in the depths of winter, when the ground freezes from November through March, these children spend five to six hours daily in the cold, moving constantly to stay warm.

What makes this routine remarkable is not just the commitment to outdoor time, but what science is discovering about what that time does to a child's body. A study conducted in Finland found that children who played regularly in grass and low vegetation for just twenty-eight days showed measurable changes in their immune systems. Researchers discovered increased microbial diversity on their skin and in their intestines—a sign of a healthier immune response. The children developed more T-lymphocytes, the white blood cells crucial to fighting infection. Their blood plasma showed higher levels of anti-inflammatory molecules. The lead researcher, Aki Sinkkonen of Finland's Natural Resources Institute, concluded that regular nature contact prevents immune disorders like allergies and autoimmune diseases. Forests, it turns out, harbor far greater microbial diversity than urban environments. Exposure to that diversity, early and often, trains a child's immune system to function more robustly.

Samuli Rabinowitsch, who leads the Samoojat group, has observed this firsthand. The children in his care get dirt in their mouths constantly and rarely catch colds. A local school nurse noticed something else: some of the Samoojat children had lung capacity, motor coordination, and overall physical fitness well above average. She called Rabinowitsch to ask what he was doing with them. But the immune benefits are only part of the story. Researchers have documented that outdoor education builds psychological resilience, improves behavior and social skills, and increases self-control. On the day a visitor observed the group, a five-year-old named Ronja led the children through rocky terrain to the camp. She counted heads to ensure no one was missing, then organized a singing session and posed simple questions about the season, sunrise, and weather. The other children raised their hands eagerly, waiting to be called on. It was a small demonstration of leadership, but it revealed something larger: these children solve problems together, help one another when they fall, and encourage each other even when tired. "These children can do anything," Rabinowitsch says.

Keeping children safe in extreme cold requires more than enthusiasm. It requires knowledge. Children are more vulnerable to cold than adults because their skin surface is proportionally larger relative to body weight, they have less subcutaneous fat for insulation, and their muscles produce heat less efficiently when they shiver. Tiina Ikäheimo, a professor at the University of the Arctic in Norway, explains that proper clothing is essential—thermal layers, warm coats, waterproof shells, snow gear. But clothing alone is not enough. Children must be supervised constantly, their extremities checked regularly, and wet clothing changed immediately. They must keep moving; exercise generates body heat. And they must be fed adequately and given warm liquids. Yet there is an advantage children possess: they are naturally more active than adults. When children are engaged in play, in adventure with friends in a beautiful place, they become especially resistant to cold. Moreover, bodies adapt to repeated cold exposure. The stress diminishes. The sensation of cold lessens. As Mike Tipton, a professor of human physiology at the University of Portsmouth, notes, there are actually more cold-related injuries in places like Italy, where people are unaccustomed to winter, than in Finland, where children learn from infancy how to behave in cold and dress appropriately.

The question that follows is practical: what about children who live in cities, in concrete jungles where forest schools are not available? Fifty-six percent of the world's population now lives in densely populated urban areas. Annina Kuusisto, an early childhood education professor at the University of Helsinki, argues that the benefits of nature contact do not require wilderness. Caring for plants, feeding pets, observing insects in a park—these activities develop respect for the environment and help children understand that living things need care to survive. She conducted a study in which she gave forty-five children an iPad for a week and asked them to photograph or film the most meaningful part of their day. Nature appeared first, every single day, mentioned by every child. Carol Murdoch, a consultant who helps British teachers offer outdoor education, has taken children to libraries, supermarkets, and playgrounds with concrete floors. She once organized a visit where primary school students who had studied marine animals went to a small town near Glasgow and measured out the length of a whale in chalk on a playground. They could finally grasp its true size. The lesson is that outdoor education is not confined to forests. It lives in any space where a child can observe, measure, touch, and wonder.

Back at Hopealaakso, Rabinowitsch describes the Samoojat children with visible pride. They remove their own shoes and peel off layers before napping. They serve themselves at lunch with large utensils, handling fish, potatoes, and salad with competence. They pack their own backpacks—four to six kilograms each—without complaint. They assemble and disassemble tents with minimal instruction. Their eyes light up when morning comes and they head to the forest. In the afternoon, when their parents pick them up, the children do not ask to go to the playground. They ask to go back to the forest. "They are forest children," Rabinowitsch says, and in that simple phrase lies the entire point: that a child who spends her days in nature becomes something different—more capable, more resilient, more connected to the world around her, and more likely to protect it.