Americans tend to be indoor people. A scientific study found that on average Americans spend 87 percent of their time inside their homes, and another 6 percent of their time inside their cars. That only leaves 7 percent of time spent in any kind of contact with nature, often at a sporting event, or maybe on a jogging trail, or just walking from mall to car and back.  Germans, Poles, and Japanese spend even more time indoors than Americans.
Air pollution outdoors is a problem in many parts of the world, but indoor air quality is even worse. It's certainly not a problem you can solve with air freshener. Air fresheners release microscopic particles that can injure your lungs. The remodeling of your lungs in ways that can cause COPD may not be detected for many years .
Indoor air pollution also isn't a problem you can solve with houseplants. They break down some of the toxic chemicals that get into room air from household products . They certainly make people feel better .But even a house full of plants fails to have even 1 percent more oxygen than a house without them. There is simply too much CO2 for plants to process with photosynthesis. Indoor CO2 levels are often five times higher than CO2 levels outdoors . Schools can be even worse .
It's no wonder that hundreds of millions of people around the world seek shortness of breath treatment. There's just no substitute for getting outdoors for better air quality. And there is no better air quality to be found anywhere than in an old-growth forest.
What Is Shinrin-Yoku?
The healing power of therapeutic landscapes has been recognized for centuries in Japan. Gardens are traditionally places of harmony, beauty, and peace. Simply looking at a Japanese garden is clinically proven to improve mood and cardiovascular health  Walking through a garden or through the forest can do much more. In 1982, the Japanese Ministry of Agriculture, Forestry and Fisheries coined the term "shinrin yoku," literally "forest desire," to describe the practice of walking through the woods for health.
I tried to use the term in a book on Japanese medicine in 1997, and my publisher replied that "nobody would ever be interested in that." However, in 2017, "shinrin yoku" is regarded in the United States as the "new yoga," a gentle exercise that has real and lasting health benefits.
What Kinds of Health Benefits Are Associated with Shinrin Yoku?
There have been at least 60 clinical studies of shinrin yoku as a kind of nature therapy — the forest therapy . Experts define nature therapy as “a set of practices aimed at achieving ‘preventive medical effects’ through exposure to natural stimuli that render a state of physiological relaxation and boost the weakened immune functions to prevent diseases”  Japanese scientists have investigated the effects of the smell of the forest. One research team found that the scent of the Hinoki cypress reduced oxygen flow to the right frontal cortex of the brain and increased activity in the parasympathetic nervous system. In other words, they confirmed in an objective way that the scent of cypress is relaxing . Researchers also found this physiological effect from stopping to smell the roses , that is, literal, physical roses. Another research team in Japan found that a few days of walking in the woods left people more enthusiastic about getting up in the morning .
Other studies confirm that shinrin yoku lowers the production of the stress hormone cortisol, slows the pulse, lowers blood pressure, and increases the variability of heart rate in response to stress in healthy ways [12, 13, 14]. Shinrin yoku also:
- Lowers blood sugar levels in diabetics .
- Lowers blood pressure .
- Reduces the "fight or flight responses" that can undo the effects of natural ways to treat dyspnea (shortness of breath).
What Kinds of Breathing Problems Respond Best to Shinrin Yoku?
Walking in the woods is wilderness, forest therapy without the drawbacks of isolation in the wild. It is most helpful for breathing problems that are aggravated by rumination, getting hung up in your own problems so much that anxiety results . It helps people breathe more easily when they are even anxious about being anxious . The benefits of "bathing" in the forest air can be undone by taking your walk when the trees are pollinating, but in every forest there are some times in the year when allergens are minimal and relaxation is optimal.
The benefits of shinrin yoku tend to last for several weeks after the walk. Even if you can only get away to relax in the forest once a month, a walk in the woods will leave you feeling more relaxed, calmer, and better equipped to meet life's challenges. Shinrin yoku won't cure asthma, chronic bronchitis, or COPD, but it usually helps. And if you can't muster the energy to walk through the woods, simply sitting in the woods and taking in the scents has many of the same benefits.