Cedar leaf oil vapor in buildings and forests: Health benefits & mechanisms

Abstract

Many people today experience symptoms indicative of chronic stress, which is manifest as persistent or frequent inflammation in one or more parts of the body. These conditions may be the result of current lifestyles, including the buildings that they work or live in, a situation referred to as sick building syndrome (SBS). Relief may be obtained by incorporating cedar leaf oil vapor into ventilation (HVAC) systems, or by spending time in a forest containing cedar-like trees or similar conifers that exude volatile compounds (terpenes) from their leaves, an experience which often leads to an improvement in health parameters. This procedure is referred to as forest bathing, or nature therapy. Many studies recently have confirmed the beneficial effects of these leaf oils and their vapors, according to a variety of laboratory experiments and field trials. Thus the cedar leaf oil terpenes have been shown in various models to inactivate many viruses and microbes directly or indirectly through activation of natural killer cells. Furthermore the terpene mixtures, and some individual tepenes, can interfere in the production of pro-inflammatory cytokines and other inflammatory mediators. This review discusses the evidence and suggests a common mechanism to explain how the leaf oil compounds, the terpenes, could relieve the chronic inflammation and stress, and consequently lead to a restoration of homeostasis.