The practice of forest bathing—basically just being in the presence of trees—became part of a national public health program in Japan in 1982 when the forestry ministry coined the phrase shinrin-yoku and promoted topiary as therapy. Nature appreciation—picnicking en masse under the cherry blossoms, for example—is a national pastime in Japan, so forest bathing quickly took.
"Forest air doesn’t just feel fresher and better—inhaling phytoncide seems to actually improve immune system function."
Experiments on forest bathing conducted by the Center for Environment, Health and Field Sciences in Japan’s Chiba University measured its physiological effects on 280 subjects in their early 20s. The team measured the subjects’ salivary cortisol (which increases with stress), blood pressure, pulse rate, and heart rate variability during a day in the city and compared those to the same biometrics taken during a day with a 30-minute forest visit. “Forest environments promote lower concentrations of cortisol, lower pulse rate, lower blood pressure, greater parasympathetic nerve activity, and lower sympathetic nerve activity than do city environments,” the study concluded.