Here is the citation:

Edwards, A., Woods, V., 2018. Forest-based Therapy: Research Letter of a Novel Regime for improved Respiratory Health. Integrative Medicine: A Clinician’s Journal.  Vol. 17, No. 1, February 2018 pages 58 – 60

and a link:
http://imjournal.com/abstracts/forest-based_therapy_research_letter_of_a_novel_regime_for_improved_respiratory_health.html