Background: Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death worldwide, responsible for 3.5 million deaths in 2021. Effective preventive measures are needed. Forest bathing has been reported to have positive effects on the immune system. In addition, the clean air, mild climate, phytoncides, high oxygen concentration, and other elements of forests are expected to have benefits for respiratory diseases such as COPD. Based on the above background, this study used a randomized crossover design to examine the improving effects of forest bathing on inflammatory markers and subjective symptoms related to COPD.
Methods: Thirty male subjects aged 63.1 ± 7.5 years were recruited after obtaining informed consent. These subjects participated in day trips to a Japanese cypress forest park and to a city area of Nagano Prefecture as a control in June 2024. Blood samples were taken in the afternoon of each day before and after the walks. Concentrations of α1-antitrypsin (α1-AT), C-reactive protein (CRP), fibrinogen, and interleukin 6 (IL-6) in blood were measured. Percutaneous oxygen saturation (SpO2), the profile of mood states (POMS), and questionnaires for subjective fatigue and respiratory symptoms and sleep quality were carried out before and after each trip.
Results: Forest bathing significantly decreased the concentrations of blood CRP, α1-AT, IL-6, and fibrinogen, significantly increased SpO2, reduced subjective fatigue and respiratory symptoms, improved sleep and the scores of positive feelings, and reduced the scores for negative emotions in POMS.
Conclusions: Forest bathing may improve inflammatory markers, SpO2, and subjective symptoms related to COPD.
Keywords: C-reactive protein; COPD; CRP; IL-6; chronic obstructive pulmonary disease; fibrinogen; forest bathing; interleukin 6; α1-antitrypsin.
© The Author(s) 2025. Published by Oxford University Press on behalf of the Japan Society for Occupational Health.