Background: Shinrin-yoku, forest bathing, has been shown to improve the pain experience in arthritis patients and the immune system in normal healthy patients. Yet, a simulated forest immersion therapy (SFIT) experience has not been tested in these two populations and specifically not in cancer patients. If SFIT complementary therapy in these two populations progresses, the intervention environment as designed needs to be tested. The purpose of this paper is to describe the SFIT setting and test the stability of the interventional environment. Methods: To operationalize SFIT, a protocol of dose delivery was designed and measured. Ambient and surface room temperatures, relative humidity, ambient ultrafine particulate matter, and volatile organic compounds, specifically terpenes, were measured prior to terpene dose delivery, every 15 min for 1 h, ending with the conclusion of terpene delivery. Results: There were nearly imperceptible differences within session means for ambient and surface room temperatures, relative humidity, ambient ultrafine particulate matter, and volatile organic compounds showing no practical significance. Room temperature and surface temperature were moderately correlated, as expected. Conclusions: The intervention room environment for the diffusion of terpenes remained stable throughout two studies. The next steps proposal to employ SFIT in the home setting is warranted, with precautions.