The Smell of Survival

I can’t begin to count how many times I was on some kind of a trip with my parents and they woke me up at dawn because it was mandatory that I watch the fucking sunrise.


Park Hyun-Soo didn’t look like a man on chemotherapy. Forty-one and with a full head of black hair, he can hike the socks off anyone, but he prefers to take his time. I met him after a basic country lunch of eight kinds of kimchi and a plate of neatly sliced homemade tofu. Eating the tofu was a little like biting into air and earth at the same time, a barely solid cloud of undemanding goodness. The kimchi, on the other hand, had a flavor as subtle as a firecracker. Each slice of cabbage, sesame leaf, radish and mystery veggie had been rubbed and soaked in hot chiles, garlic and anchovy paste. I went light on the kimchi but I’d eaten too much tofu. If Korean food is all about balancing flavors, I was clearly lopsided, as Americans tend to be. We like the easy pale food. I felt the need to walk briskly, but that wasn’t about to happen.

First, there was tea. Not exactly a forest ranger, Park is more of a ranger-slash-shaman. Remarkably, that is pretty much his official job description. He is part of a new breed of Korean Forest Agency employee known as a forest healing instructor. He’d actually gone to graduate school for this, passing rigorous entrance qualifications. He did not always aspire to this profession. He began his career as many South Koreans do, in a competitive corporate job—in his case, general manager of a hospital clinic in a city a few hours south of Seoul. But then, at age thirty-four, he received a diagnosis of chronic myeloid leukemia. He had a wife and three small children. He sought peace and recovery in the nearby woods, and it worked so well he decided to orient his entire life to the cypress trees. Here, in his mountain aerie, he stands at the forefront of South Korea’s project to medicalize nature, beginning with its immediate sensory effects.

Park greeted my translator and me in the visitor center parking lot of Jangseong Healing Forest and ushered us inside. The building was brand-new, constructed of blond woods and redolent of the pleasant, slightly acrid smell of hinoki cypress with its robust notes of turpentine-meets-Christmas tree. Park apologized for the low table in the conference room, asking me if I’d be okay sitting cross-legged on the floor. Of course! I said. Not all Americans are stiff-legged blobs of hopelessness. We drank the tea, made from benzoin tree flowers harvested here in the summer. After twenty minutes I desperately had to shift position, and pined once again for the promised walk. He was telling us that between 2,000 and 3,000 visitors come through here every month, including three to four groups per day specifically geared to some kind of healing, from cancer patients to kids with allergies to prenatal groups and everything in between. Depending on the program, participants may do activities like guided meditation, woodcrafts and tea ceremonies. But the heart of it all is walking in the hinoki forest. Yes, please!

I creaked up from the table and wobbled into the physiology room. Like all the participants, I would capture a snapshot of my stress levels before and after the program, although for me, the agenda would just be a walk, a quick squirt of cypress mist and a few moments of deep breathing. That is because, as usual, I was too busy for full-on relaxation. I had a full schedule of forests and scientists to see on my week around South Korea. Today could be called the mini-jet-lag-and-tofu-recovery program. My translator, Sepial, was even more harried than I as she had to keep track of every exchange while still responding to emails and setting up visits for me later in the week. She’s forty-four, with a teenaged son. She needed a little walk in the woods herself. “I don’t usually exercise, Florence,” she said, looking apprehensive.

We took our blood pressure and then inserted a finger for several minutes into a plastic clamp sensor that is supposed to measure our heart-rate variability. The idea was that the Korean Forest Agency will keep all these records and use them to assemble a large database for research. Individuals will be able to track their own data over time and across different forests and facilities. They should be able to tell if one walk in the woods per week is enough for them to maintain lower blood pressure, or if they better try adding more leaf-and-acorn collages to their regimen. The scope of all this was, true to Korean form, ambitious. In the same way Samsung outmaneuvered Apple and K-Pop intends to dominate Asia with American- derived pop music models, Korea is on a path to out-Japanese the Japanese in forest therapy trails and science. Here, forest bathing is called salim yok.

Although Jangseong is currently one of only three official healing forests in South Korea, thirty-four more are slated to appear in the next two years, meaning most major towns will have access to one. This forest, with its dominant cypress trees, is considered a jewel in the system. Finally, I was able to see it. We headed out to walk, first following a wide dirt road through the woods and then branching off into a narrow, well-maintained foot path. The trail skirts around 2,900-foot Chukryeong Mountain. We passed an interpretive sign claiming the woods have more oxygenated air than a city or a building, although I wondered if this isn’t offset by the gain in altitude to thinner air.

Park wore what looked to be comfy Mao-style pajamas, with a round wooden nameplate attached to his chest. He moved gracefully along while recounting the history of this ground. Like much of Korea after World War II, these mountain flanks were once completely denuded of trees. First the Japanese, who occupied Korea starting in 1910, cut the forests for timber. After the war, people scavenged whatever was left for heating fuel. Times were desperate. At $100 per capita, South Korea then had a GDP lower than that of Ghana. One-third of Koreans were homeless. Without trees to anchor the mountain in place, the mud slid and the streams choked with silt. Replanting began in earnest in the 1960s. The Japanese hinoki cypress was a favorite for its fast growth and uncanny ability to ward off pests. Jangseong is now 88 percent hinoki, and the trees are fully grown.

What makes the tree so unappetizing to insects has vaulted it to the heart of the Korean Forest Agency. It smells great. Walking through Jangseong is like moving through a picturesque vat of VapoRub. Whether or not these woods noticeably increase our oxygen supply, it feels like they do, clearing the sinuses and infusing every cell with an essence of the forest, something healthful and invigorating. Robert Louis Stevenson has a line about “that quality of air, that emanation from old trees that so wonderfully changes and renews a weary spirit.” He had a good nose. So did D. H. Lawrence, who wrote (or rather overwrote): “The piny sweetness is rousing and defiant . . . keen with aeons of sharpness. . . . I am conscious that it helps to change me, vitally. I am even conscious that shivers of energy cross my living plasm, from the tree, and I become a degree more like unto the tree, more bristling and turpentiney. . . .”

Clearly, cypress trees and the love for them are not unique to Asia. They are prized the world over for their rot-resistant wood, warm tones and pleasing scent. In ancient Egypt the tree was used for mummy cases. Cypress wood was even thought to outlast brass, and so it served as a palimpsest for Plato’s code of laws. With its rich amber bark and soaring greenery, Jangseong felt comforting, almost congregational. While I’d walked in forests in Japan, the ones I saw bore a mix of hardwoods, cypress, other native evergreens. Jangseong, though, is practically a mono crop.

In what I understood might be the Asian conception of nature, compromise would do just fine. It doesn’t have to fulfill an Emersonian purity in order to be considered sacred. I asked Park about wildlife, and he admitted there is not much here in the way of large mammals. Most have been hunted or squeezed by poor habitat into the surprisingly biologically rich Demilitarized Zone between North Korea and South Korea. People have been locked out of that 160-mile long, 2.5-mile wide buffer for decades, making it a prime candidate for an international peace park, if only North and South could agree on anything.

What these woods lack in biodiversity they make up in sensory delight and, increasingly, human medical use. “There are two and a half million individual trees here,” said Park. A subtle mist rose from them, made of the very aerosols we were smelling. Atmospherically, these serve a cloud-seeding function, helping forests regulate their moisture levels. But Park, healing instructor that he is, holds a strictly medical appreciation. “The phytoncides are antibacterial,” he said. Citing the Japanese research of Miyazaki, he continued as though he’s recited it many times before: “They reduce stress fifty-three percent and lower blood pressure five to seven percent. The soil is also good for healing. It is antiviral and the geosmin is good for cancer.” Geosmin, I learned, causes the funky-great smell of earth after a rain. Like many of the phytoncides, it is a turpene, a family of aromatic hydrocarbons and a major component of natural resin (incidentally, turpenes are also a big ingredient of hops, giving dark beer its rich flavor and aroma).

Geosmin comes from soil organisms, particularly the streptomyces bacteria that are key to so many antibiotics. According to the Royal Society of Chemistry, we are alert to this rich smell in incredibly small quantities. We can detect the equivalent of seven drops of geosmin in a swimming pool. This sensitivity likely reflects an important evolutionary adaptation because it tipped our thirsty ancestors off to sources of water. That may also explain why its presence helps put us at ease. Camels probably get off on it even more than we do. Keith Chater, the Norwich scientist who sequenced the genome of Streptomyces coelicolor in 2007, believes camels can smell geosmin in oases miles away. In return for their helpful homing service, some spores of the bacterium then hitch a camel ride to the next watering hole. Geosmin is the smell of survival.

It’s no surprise by now that Korea and Japan lead the world in the science of forest smells. There’s the Natural Killer cell work of Japan’s Qing Li, and also that of a young psychologist there named Yuko Tsunetsugo. A senior researcher with the Department of Wood Engineering at the Forestry and Forest Products Research Institute, Tsunetsugo misted fifty-two infants with the major components of hinoki: pinene and limonene. The pinene instantly lowered their heart rates four points, while the limonene and the control did not make a difference.

When I’d been in Japan at the Nippon Medical School lab of Qinq Li (the man who put subjects in hotel rooms for three nights with hinoki oil misting around them), he’d given me a demonstration of the immediate effects of the stuff. I’d put my arm in a blood-pressure cuff. Then he unscrewed the cap off the forest elixir. “This is very toxic!” he’d giggled. “It’s very good but very toxic.” When I inhaled, the oil gave off a nice, pitchy, sharp scent. We put the cap back on and read my blood pressure again. It dropped twelve points.

I’d looked at Li, who nodded delightedly. “This is a very big effect, bigger than people get with pharmaceuticals!”

Meanwhile, here at the government-funded Korea Forest Research Institute, scientists distill essential oils and study them for effects on allergies and their ability to kill staph bacteria. Among the things they’ve found are that coniferous essential oils fight atopic skin diseases (when applied to the skin in low concentrations), mitigate stress by lowering levels of cortisol (when inhaled), and reduce symptoms of asthma (ditto). The major components of hinoki oil are camphor, turpenes, pinenes and humulenes, limonenes and sabinenes, depending on the season and the part of the tree sampled. The sabinenes seem particularly helpful for treating asthma, the terrines for fighting bacterial infections and stress.

I may not have been actively nursing any infections, but after a few minutes of walking I felt more awake than I had all day. We stopped where a wooden boardwalk crosses a small wetland lined with dogwoods and connects two drier parts of the trail. Park pointed out a citronella plant and a Japanese cedar, also prized for anti-infective properties. He asked us to close our eyes and take deep breaths. Then he led us in some gentle stretches. Sepial stashed her notebook into the recesses of her trench coat. We raised our arms over our heads, then down, then back up, all while breathing slowly. The birds chirped. The wind blew gently through the high branches, and the sun mixed with the cool autumn air. He told us to look at the still pond of water just beyond the trail. “Look through the lake, watch the reflections of the trees. This is good for the brain to see. Pretend this is your mind. Take deep breaths. The trees you see there could be real, or they could be fake, just reflections. This is like your mind. When a depressed person sees depression, it could be an illusion. It’s not really there. You can separate the emotion from the mind.”

Maybe it was the translation, but things seemed to be bleeding out of the realm of quantifiable science and into a squigglier place. Was the mysticism biasing the science and making it suspect, or was it more like a portal allowing the scientists a point of entry where Westerners don’t always feel comfortable? Or a little of both? I wasn’t sure.

FOR THREE YEARS, Park had walked mindfully in these woods every single day. “I’m one hundred percent sure it is helping me,” said the ranger, who is in remission. “When I was first diagnosed, I had all kinds of fear and anxiety. I am happy now. I have zero percent anxiety. People learn from nature that they can heal. Now it is my duty to be a bridge between nature and people.” He said he’s grateful to the leukemia for redirecting his life. It’s hard to say, though, what’s really helping Park and the many who flock to these places. Is it the exercise? Park wears a bracelet that measures his steps. He takes 15,000 a day, about 6 miles. He also believes the forest heals him, and the power of belief is hard to overestimate.

It also may be contagious. Park is a compelling teacher who wants to help other people turn away from stress and toward something more meaningful than the punishing grind of work and study. He doesn’t force his kids to attend the pervasive after-school schools—called hagwons—that so many kids slouch off to, forgoing sports, play and just goofing off. His oldest son now attends a “timber school” for high school where he learns about forest management.

Park told me he thinks Korea has entered “Peak Stress.” It’s an interesting idea. Flying out of poverty and through a series of dictatorships to become one of the wealthiest democracies on the planet, the nation now boasts the fourteenth-strongest economy in the world. An incredible 98 percent of South Koreans graduate from junior college or university, the highest rate in the world. But the meteoric success has come at a great cost. South Koreans work 2,193 hours per year on average, the highest figure in the OECD. More than 70 percent report their jobs make them depressed, according to a survey by one of the country’s biggest employers, Samsung.

And the problems aren’t confined to the workforce. Ninety-six percent of high school students reportedly do not get enough sleep. A 2011 survey found 87.9 percent of them feeling stress “in the past week.” Teenagers in Japan, China and the United States report half that level. South Koreans are, according to researchers at Yonsei University, the unhappiest students in any industrialized nation. In a country where mental illness is highly stigmatized, South Koreans have the highest suicide rate in the world.

But now that they’ve achieved some measure of security and material success, some are actively seeking a happier existence. South Koreans are buying into the booming spa and cosmetics cultures, and, increasingly, yearning for the mystical mountains and forests of the deep Korean past. Since it arrived here in the fourth century, Buddhism blended nicely with the peninsula’s ancient animistic shamanism, the idea that natural objects have a spirit. In Korea, one of the most powerful spirits is the sanshin, the mountain spirit. Trees, too, have long been venerated as guardians of people and villages.

By the fourteenth century, though, Korean rulers would find in China-originated Confucianism—with its teachings of regimented status, societal obligations and an uncompromising work ethic—a politically convenient philosophy for growing a nation state. There now exists an uneasy and unequal détente between opposites: a technology-touting, competitive and hierarchical system on the one hand and the nature-affiliated spirits-are-everywhere firmament on the other.

Euny Hong, in her irreverent cultural history of Korea, The Birth of Korean Cool, explains an ancient proverb, “shin to bul ee,” which means “body and soil are one.” Not soul, but soil. “It’s a concept that predates Confucianism or any official organized belief,” she writes, “which is why this idea seems incongruous with what Seoul looks like today—jam-packed skyscrapers with very little open space.”

While most Koreans would be uncomfortable with the idea of psychotherapy, they do nonetheless place great authority on traditional shamanlike healers, called musok-in. By some estimates, up to 80 percent of Koreans loosely adhere to shamanism in some form, often while also identifying as Christians, Buddhists or atheists.

What it means today is that the forest trails are starting to fill up with pale, urban weekend refugees, not so unlike Sepial and me. After about an hour and half of leisurely walking, we circled back to the visitors center. We gamely stuck our extremities back into the machines for a quick physiology check. I clocked a nice little drop in my blood pressure, from 111 over 73 to 107 over 61. So far, chalk one up for Nature. But Sepial’s blood pressure was a few points higher, and my heart-rate variability data didn’t show much improvement after the 90-minute walk. Park sat down with us to go over the charts, which were in Korean, with confounding splashes of dots strewn across an axis. Looking at Sepial’s data, Park told her that because she wasn’t used to exercise, the walk had actually stressed her out physiologically. “You need to exercise more,” he said. It seemed a logical prescription. Don’t health-care practitioners always say that?

As for me, Park said that while my overall stress levels seem healthy, my chart indicated that the balance between my sympathetic nervous system and my parasympathetic nervous system is out of whack. I know how to amp my system up with exercise and activity, but I could use more practice damping it down. In other words, Sepial and I appeared to be opposites. “Meditation could be good for you,” he said. In more bad news, the HRV machine mysteriously gave a read on how thick my blood vessels are. Mine were showing some signs of thickening, and any time the word “thickening” applies to you, it’s not auspicious. Vessels naturally thicken with age, getting stiffer and less flexible. They have a harder time delivering oxygen where it needs to go and making micro adjustments to the nervous system. “You must control your food and diet,” he said. Okay, then: more kimchi for me.

WHAT HAPPENS IF you take someone with a fairly radical notion of happiness and set him loose to make national policy? The answer might look like Bhutan, where the king and his retired-king father ride bicycles up and down mountains with shit-eating grins on their faces and encourage the populace to do the same. Or it might look like Singapore, where the late Lee Kuan Yew, the prime minister for twenty-five years, ordered free schools, decent housing and the planting of over a million trees. Increasingly, it might look like South Korea. The man with the grin on his face is an influential academic named Shin Won-Sop.

To understand just how committed Korea is to better-health-through-forests, I paid a visit to the headquarters of the Korean Forest Agency in the new industrial city of Deajun. There I was pleased to find my old shinrin yoku contact Juyoung Lee, who’d been hired away from his post in Japan to conduct research for South Korea. Lee now works for the agency’s human welfare division. It’s remarkable that any forest agency even has a “human welfare” division. It wasn’t so long ago that the main job of forest agencies the world over was simply to facilitate cutting down forests. When I first met Lee two years earlier, he was swatting mosquitoes and suctioning sensors off my forehead on a Japanese mountainside. Now he wore a stylish suit in a modern high-rise filled with pink cubicles. (Not sure what the significance of the pink was, but I can’t resist reporting that the city of Seoul recently spent $100 million painting special parking spaces pink for women. They are supposed to make women happy, but they are also longer and wider, leading many not to feel happy but to feel insulted by the implied dig on their driving ability.)

Lee escorted me through the maze of pink to the spacious outer office of Dr. Shin, who is the minister of the Korean Forest Agency. Shin greeted me with a handshake and a delicate cup of tea. He is boyish and buoyant, as if he can’t quite believe his good fortune to land the corner office. He did not rise to the top of the agency by the usual route in timber management, but rather because of his psychology research on such topics as “the influence of interaction with the forest on cognitive function” and “the influence of forest experience on self-actualization.” For that paper, which he published while based at the University of Toronto, he studied how participants changed after a five-week wilderness course sponsored by the National Outdoor Leadership School and found the results inspiring. He’d been influenced by Stephen and Rachel Kaplan’s work at the University of Michigan. Shin became a professor of “social forestry” at Chungbuk National University, which offers the world’s only degree program in forest healing. In the early days of research, “we discussed a lot of the issues for how we can objectively measure the benefits and what are the best biomarkers,” he said.

Apparently, the effort paid off. Shin’s ascendancy and the country’s new programs reflect just how seriously South Korea takes the emerging evidence on nature and health. The goal of the current National Forest Plan is “to realize a green welfare state, where the entire nation enjoys well-being.” As Shin pointed out, happiness is now part of the national index. And the results of this campaign are evident: visits to the country’s forests increased from 9.4 million in 2010 to 12.7 million in 2013, or one-sixth of the country’s population (around the same time, visits to national forests in the U.S. dropped by 25 percent). The agency now offers everything from prenatal classes in the woods to forest kindergartens to forest burial options. It’s a cradle-to-grave operation. There is even a “Happy Train” that delivers school bullies to a national forest for two days so they can learn to be nicer. To unwind in the United States, men in groups might hunt and drink Jack Daniels. Here they do downward dog and make floral collages. Earlier in the week at a forest named Saneum, I’d come upon a forest-healing program for firefighters with PTSD, where the men were practicing partner yoga in the woods and massaging lavender oil into each other’s forearms.

The data on the healing power of the forests kept rolling in. Among the things the Korean researchers were finding: immune-boosting killer T cells of women with breast cancer increased after a two-week forest visit and stayed elevated for fourteen days; people who exercised in nature (as opposed to the city) achieved better fitness and were more likely to keep exercising; and unmarried pregnant woman in the forest prenatal classes significantly reduced their symptoms of depression and anxiety.

What’s needed now, Shin told me, is better data on individual diseases and on the specific nature qualities that really deliver. “What are the main factors in the forest that are most responsible for the physiological benefits, and what types of forests are more effective?” he asks. “And the other thing, how do we make the people more interested? And discussing how that forest benefit can be applied in the medical field and the insurance field.” The agency estimates that forest healing reduces medical costs, creates new jobs and benefits local economies.

In addition to designating dozens of official healing forests and constructing facilities there, the Forest Agency is building an ambitious $100 million forest healing complex adjacent to the country’s iconic Sobaeksan National Park, complete with aquatic center, addiction treatment center, “barefoot garden,” herb garden, open-air decks, suspension bridge and 50 kilometers of trails. It’s hard not to think of this as Disney meets summer camp. Because make no mistake: as much as Koreans may yearn for meaning, they are pragmatists. The nature renaissance here is largely about consumerism, albeit a medical consumerism. The forest developments are public-private partnerships, where real estate and resort investments will generate profits, where shops will sell phytoceuticals (hinoki bath oil, anyone?) and where people will be able to return to their schools and offices more productive than when they left.

I glimpsed this hybrid future at a resort called Healience. Upon arriving at the bucolic setting near the Saneum Forest, I was handed a purple jumpsuit to wear during my stay, part Miraval, part Sing Sing. I joined others wearing these suits as we scrambled over barefoot forest-walking trails, waited for massages and bused our cafeteria trays. The lobby shop was a shrine to hinoki, selling atomizing humidifiers and artfully packaged glycerine soaps. I ended up with a tube of phytoncide toothpaste. It tasted like gnashing a holiday wreath between your molars. That’s not what gave me pause about putting it in my mouth. I was having a hard time getting past the fact that phytoncide is basically pesticide. There’s nothing coy about the name. “Cide” means “kill.” I pictured ants crawling up the trees and dying in twisted, tortured poses while sending farewell signals to their loved ones. At the very least it seems like the place could benefit from some rebranding. Do we really want to brush with the stuff and hike on “phytoncide trails?” I was also, to be honest, skeptical of the whole aromatherapy thing because its primary adherents, at least in the United States, also lean toward crystal worship and misshapen footwear.

But the real story with these compounds is both more complicated and more interesting. In the quest to find out what exactly it is about nature that meshes with our minds, smells emerge as an undersung but powerful component. Visuals tend to get all the acclaim, but as Proust knew, nothing hits the brain’s emotional neurons more powerfully than odor. Scents immediately enter the primal brain, where the amygdala is waiting to command a fight-or-flight response. The emotional amygdala is highly wired to the hippocampus, where memories are stored. A keen sense of smell was critical as we sought food and water in scarce environments.

Astonishingly, the human nose can detect 1 trillion odors, including many we don’t even realize we are detecting. It’s well known that women living together in dorm rooms are able to synchronize their menstrual cycles; the reason is they are nasally detecting each other’s pheromones. Women may have a keener sense of smell than men, and it sharpens during pregnancy, when they must be alert to subtle hazards. Diane Ackerman writes in A Natural History of the Senses that mothers can identify their babies by scent alone, but fathers can’t. My sense of smell is my sharpest sense, for better or worse. My nose detects hazards before my husband’s, such as something burning that is not supposed to be burning, and it gets my heart beating very fast, a classic fear response.

We’ve all heard that horses and dogs can smell fear, but it turns out that humans can too. To prove this, researchers collected undershirts of men who went skydiving for the first time. They then presented study subjects with either those shirts or ones worn by men who did nothing scary. The researchers measured elevated stress hormones only in the subjects who smelled the skydiver sweat. They smelled the terror and then caught it too. Fear detection is a handy skill in a social animal.

Sadly, though, our brilliant sense of smell may be on the wane. Svante Pääbo is the Swedish paleogeneticist famous for sequencing the genome of Neanderthals and discovering that they interbred with early Asiatic humans (the result: all modern humans, except Africans). From genetic evidence, he posits we are drastically losing our sense of smell. We have a thousand genes involved in nasal reception, but over half of them have become inactivated due to mutations. In wild apes, only around 30 percent of the smell genes are dysfunctional. Presumably, the mutations persist in humans because losing some smell ability no longer affects our survival. We no longer use our noses to find food, except perhaps Cinnabons in the airport. In fact, we would rather not experience many of the smells of city living. We refrigerate our food, but we don’t refrigerate our garbage. Once proud, this superpower is devolving.

Certainly, we are not the sensory animals we used to be, and neither are the animals we’ve domesticated. Wolves outperform dogs in tests of general intelligence. Domestic cats differ from wild cats in some interesting ways having to do with skull size and foraging smarts. Which raises the provocative question: what about us? Are we self-domesticating? Of course, argues Harvard primatologist Richard Wrangham, who makes a particular case for humans becoming less aggressive as we’ve evolved into larger social groups. Our brain size and musculature peaked during the last ice age. Our teeth have gotten smaller, our long-distance vision worse. Since we settled down in farming communities around 10,000 years ago, we’ve grown weaker, and no doubt in some ways, dumber. The fast-firing sensory neurons we needed to stay alive in dynamic wild environments have, shall we say, relaxed. Of course we’ve gotten good at some things, like negotiating traffic circles and thumb eye coordination for text-messaging. Scientists have shown that the hippocampi of London cabdrivers grow as they learn to map the city. Our individual brains are adapting to handle modern life, even from one year to the next, but that reflects flexibility, not evolution. In the mismatch between our current lives and our current brains, the primary victim is our paleolithic nervous system. No wonder, then, that when something smells really great we get happy. It’s as though we’ve momentarily stepped through the wardrobe.

SMELLS HOLD POWER over us because the nose is a direct pathway to the brain. This is why some drugs are administered nasally. Molecules of a certain size that enter through the nose bypass the blood brain barrier and march right into the gray matter. While this shortcut is convenient for pharmaceutical companies, it’s less helpful in a world filled with pollution. Scientists have known for a long time that particulate matter from sources like diesel shortens life spans by causing cardiovascular and pulmonary problems. Black carbon—the tiny particles spewed out in exhaust and other combustion reactions like fires and cookstoves—are blamed for 2.1 million premature deaths annually around the world. Scientists have long considered the lungs as a primary target of pollution. Only recently have they come to realize the role of the nose as thruway to the brain; the nefarious extent of the nose-brain connection was only illuminated in 2003, when researchers in smog-choked Mexico City found weird brain lesions on stray dogs.

This is unnerving, because particulate pollution is all around us. It’s very likely a strong factor in why going to the woods makes us feel better and more cognitively nimble. In the humid microclimates created by urban forests, leaves soak up particulate pollution. Beneath the trees, organic carbon in the soil can bind to airborne pollutants, and it also helps clean surface water in storms. A 2014 study estimated that trees in the United States remove 17.4 million tons of air pollution per year, providing 6.8 billion dollars in human health benefits.

I was curious about how the dynamics were playing out in my neighborhood. Before I went to Korea, I borrowed a portable aetholometer from Columbia University’s Lamont-Doherty Earth Observatory. The device comes from the Greek word meaning “to blacken with soot.” Velcroed into a twill vest pocket, it sent up a spindly arm sensor that poked out of my collar like a playful pet monkey. I wore it around D.C. for three days of my normal routine of working, walking and driving. Columbia’s Steve Chillrud, codirector of the Observatory’s Exposure Assessment Facility Core, helped me collate the data to a real-time GPS tracker in my phone and analyze the results. Not surprisingly, I measured high readings of 6,000 nanograms per cubic meter while driving on I-495, the Capital Beltway, even during off-peak hours. More shocking, though, I recorded equally high values in my kids’ school parking lots, where cars and buses idle waiting to pick up students gathered outside. Nineteen percent of Americans live near “high-volume” roads, and most cities don’t monitor these corridors for air quality.

Regardless of your income, the closer you live to these roads, the higher your risk of autism, stroke and cognitive decline in aging, although the exact reasons haven’t been teased out. Many scientists suspect it has something to do with fine particles causing tissue inflammation and altering gene expression in the brain’s immune cells. “I hold my breath when I’m behind a diesel bus,” said Michelle Block, a neurobiologist who studies pollution’s effects on microglial cells at Virginia Commonwealth University. It’s all another reason to spend time in the woods.

It makes sense that if some nasally routed molecules are bad for the brain, others might be good. We’ve known for millennia that smells can influence our moods, behaviors and health. Aromatherapy, or using fragrance specifically to help heal the sick, dates back to ancient Egypt. Cleopatra, that clever girl, reportedly used rose petals to lure Marc Antony to her bed. On a less legendary scale, retail stores and consumer product manufacturers know how to exploit the nose-brain connection. In the words of the academics who study such things, pleasant smells trigger “approach behavior.” If a store smells good, we’ll walk in and linger. In one study, participants cleaned their lunch area more assiduously if they smelled citrus. Even Windex changes our behavior. People assigned to a room sprayed with the pungent cleaner expressed a greater willingness to volunteer and donate money to a cause than participants in a neutral- smelling room. The hypothesis is that the smell of “cleanliness” makes us aspirational. Who knew: Windex is the smell of virtue.

When we say we can smell spring, we are really smelling tree aerosols. As the air temperature heats up, so do the biochemical reactions within the wood and leaves. Evergreen forests smell strongest in midsummer, which is also when pests are busiest. The so-called “pinosylvin” in pine trees and the terpinoids of cypress trees both stimulate respiration and act as mild sedatives, relaxing us.

Although aromatherapy is the most popular alternative treatment for anxiety worldwide, it hasn’t been well studied in large, clinical trials. A review of the literature in 2011 found that while most studies showed beneficial effects, it was hard to tease out the power of the placebo effect in most of them. Nonetheless, the authors concluded it’s “a safe and pleasant intervention.” Since then, a large study found that 80 percent of cancer patients in the National Health Service of the U.K. reported significantly less anxiety while using “aromasticks.” That’s bigger than just a placebo effect, but the authors didn’t know how the smells might be working. Other studies have reported that scents like lavender and rosemary cause both drops in subjects’ cortisol levels and increased blood velocity to the heart (a good thing).

If you believe something can make you feel better, it sometimes does. The imagination is a powerful healer. Moreover, what if it’s not necessarily nature that’s helping us, but the absence of something else? Walking around sniffing the fresh hinoki forest, I had to wonder if some of the benefits attributed to these mystical woods are the simple result of not being in the city. If air pollution is so bad for us, getting out of town, even if it means sitting inside an aluminum box on a rural parking lot, might look pretty beneficial by comparison. Regardless of whether people know exactly how polluted their neighborhoods are, their psyches seem to know. In one survey of 400 Londoners, “life satisfaction” fell significantly—half a point on an 11-point scale—for each additional 10 milligrams per square meter of nitrogen dioxide pollution.

If less pollution makes us feel better, the same could be said of a reduction of noise, crowds, unwelcome distractions and, sometimes, technology. The latter is a big deal in Korea, the most wired country in the world. More than 90 percent of homes here have high-speed Internet access. As of 2013, the country had the fastest download speeds in the world, 40 percent faster than the number-two country, Japan, and six times faster than the world average. Video gaming is so big that it’s a spectator sport, filling huge stadiums with fans watching sallow contenders push buttons on consoles.

In 2010 a young South Korean man collapsed and died after playing fifty straight hours of StarCraft, prompting the government to ban some games between midnight and 6 A.M. for anyone under sixteen. According to the National Information Society Agency, 8 percent of Koreans under age forty suffer from gaming addiction, with the figure rising to 14 percent for kids between the ages of nine and twelve. The government earmarked billions of won for counseling and education about the dangers of too much time on screens. These include poor grades, compromised sleep and family strife. Adults, meanwhile, evince slightly different symptoms. A survey of 500 office workers claimed their cellphones caused slouchy posture (32.7 percent), vision deterioration (32.5 percent) and finger pain (18.8 percent). The term “addiction” is controversial, but there are questionnaires to help identify distressing signs. Keeling over dead is a tip-off.

Perhaps it’s inevitable that digital detox would find its way into the country’s parks and forests. Nobody is happier to see it there than Kim Jooyoun. Like Park, she is one of the new healing instructors trained by the Korean Forest Agency. A mother herself, she understands the pressures on young Koreans and their striving families. Some years back, when her own daughter was fourteen, Kim found her literally pulling her hair out from stress. “Ever since then,” she told me, “the child comes first.” On Saturdays, Kim teaches a digital detox program for preteens in one of Seoul’s big parks, Bukhansan. I visited on a glorious fall day, when hundreds of Koreans in smart outdoor attire moved like ants up the park’s hilly trails. By the time I got there, seven boys were lying still like lizards on turquoise yoga mats in a relatively secluded grove. Kim was having them listen to the sounds of nature.

“If you want to play games better, you need to let your eyes rest,” she told them. The boys’ mothers hung about. This was week two of the free ten-week program, and they’d signed them up through the City of Seoul, having attested to their sons’ obsessive behavior either playing video games like League of Legends or texting on their smartphones. I wondered why ten-year-olds even had smartphones, but that horse was clearly out of the barn.

I could see that Kim’s forest program was as much for the stressed-out mothers as it was for the boys. The session included a clever mix of games, sensory interludes and trust exercises. Kim arranged everyone in a circle, each person holding a shoulder-high twig. Then she gave a command and each person lunged to the spot of the person next to him in time to catch their neighbor’s twig before it fell. Then they switched direction. They made the circle bigger and the lunges faster. The boys, who had looked bored when it began, were soon laughing with their moms and stumbling into them. Next, Kim asked the mothers to put on blindfolds and allow their sons to lead them.

“I’m going to give you a chance to care for your mother since she’s always caring for you,” she explained to the boys. “The course where you will take her is not safe. There are lots of rocks and sticks.” They walked carefully around for a while and then they switched places, the blinded sons alongside or just in front of their mothers. “Usually parents drag kids around with their intentions,” said Kim to the moms. “The one who follows has no power at all, even though intentions are good. Don’t talk too much and relax. If there is a tree in front, kids can sense it, so don’t worry too much, and let the kids lead. Give them some space.”

After that, Kim and her assistant led the boys on a slippery hike up a riverbed, one that would challenge them and not patronize them, she told me. It’s not easy to compete with multi-player gaming, but she had the boys’ full attention. The moms brought up the rear, stopping frequently for selfies. If the intention was to demonize smartphone use, they weren’t exactly modeling good behavior. I learned, though, that tech abstention isn’t the goal, any more than a dietary cleanse leads to anorexia. Unplugging isn’t realistic, and seeing the Korean kids made me understand this in a new way. For many of these kids, gaming is the only play they get, and certainly the only play unsupervised by adults.

“They’re not allowed to play outside at school,” one of the moms told me. While there are spectacular parks in Seoul, they tend to be few and far between. Playgrounds are often covered in asphalt, small and claustrophobic. And the kids go to study programs after school, leaving little time for sports. They have it worse than their American counterparts, but I had to acknowledge that many of our kids, ever losing recess, unstructured play and time without adults, are not that much better off. No wonder they’re meeting up in a galaxy far, far away.

Kim wants to help these families find a respectful balance of power between parent and child, an equilibrium between technology and human interaction, and healthier outlets for preteen anxiety, energy and aggression. She believes time outside can offer this. “In nature, they have to use all their muscles and senses. They develop body sense. They get scared but they develop self-confidence. They develop more ability to solve problems themselves.”

The science backs her up. Two South Korean studies looked at eleven- and twelve-year-olds who qualified as borderline technology addicts. After trips to the forest of two days each, researchers found both lowered cortisol levels and significant improvements in measures of self-esteem, and the benefits lasted for two weeks. Time in the forest also led them to report feeling happier, less anxious and more optimistic about their futures, according to the lead study author, Park Bum-Jin, a professor at the Lab of Forest Environment and Human Health at Chungnam National University. A couple of days after Kim’s program, I met him for green tea in the Seoul offices of the Korea Forest Foundation.

“Kids with higher self-esteem are less likely to get addicted,” he told me. Based on this work, he recommends that preteens get out in nature for a half day or so every two weeks. “The philosophy of this research is simple,” he explained. For these kids, “time spent in forest is not more interesting than video games, like fruit is not more delicious than junk food. We cannot make them stop playing games. As we get older, we have a tipping point in judgment that we need more fruits than junk food. As far as some time in forest, they can’t play games during that time. As long as playing in forest is just fun itself, it can make that tipping point come earlier.”

Park applauds the national plan that shepherds citizens into the forests through work and school programs. Koreans have been so intensively urban for long enough now—two or three generations—that they don’t necessarily know what to do with themselves in the woods. In this Confucian culture of master and student, it makes sense to use rangers, guides and demarcated spaces—this hillside is for healing! This one is for plain old recreation! Camp on this platform here! Park pointed out that many Koreans have no hankering whatsoever to get back to the land, so it’s especially important to catch kids early enough that they learn a sense of ease in nature. Interestingly, E. O. Wilson believes that the best window for the conditioned learning of biophilia is before adolescence.

The forest campaign can’t come a moment too soon, Park said. He fears a loss of transmission from one generation to the next. “Children and the younger generation don’t really have experience in nature; so many of them think of the forest as dirty or scary. If we don’t change their mind-set now, there will be no chance.” Park himself, now in his early forties, grew up in the city with little time outdoors. Because of what he’s learned, he takes his two kids hiking regularly. It’s their vegetable, and they’re dutifully consuming it.

Nature, for Park, is in some ways a negative space, a refuge from ills. It is the anticity, even when it’s within a city. “Cities are a human zoo and I think schools are a human zoo too,” Park continued. “We cannot give up those systems, city and schools. The forest is the only exit we have for those humans who live in the human zoo.”

If the Koreans can learn to love nature, maybe anyone can.




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