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. 2021 Feb 3;18(4):1416.
doi: 10.3390/ijerph18041416.

Nature Exposure and Its Effects on Immune System Functioning: A Systematic Review

Liisa Andersen  1 , Sus Sola Sola Corazon  1 , Ulrika Karlsson Karlsson Stigsdotter  1
Affiliations

Nature Exposure and Its Effects on Immune System Functioning: A Systematic Review

Liisa Andersen et al. Int J Environ Res Public Health. .

Abstract

Given the drastic changes in our lifestyles and ecosystems worldwide, the potential health effects of natural environments have grown into a highly pervasive topic. Recent scientific findings suggest beneficial effects from nature exposure on human immune responses. This review aims at providing a comprehensive overview of literature published on immunomodulatory effects of nature exposure by inhalation of natural substances. A systematic database search was performed in SCOPUS and PubMed. The quality and potential bias of included studies (n = 33) were assessed by applying the EPHPP (Effective Public Health Practice Project) tool for human studies and the ARRIVE (Animal Research: Reporting of In Vivo Experiments) and SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation) tools for animal studies. The synthesis of reviewed studies points to positive effects of nature exposure on immunological health parameters; such as anti-inflammatory, anti-allergic, anti-asthmatic effects or increased NK (natural killer) cell activity. Decreased expression of pro-inflammatory molecules, infiltration of leukocytes and release of cytotoxic mediators are outcomes that may serve as a baseline for further studies. However, partially weak study designs evoked uncertainties about outcome reproducibility and key questions remain open concerning effect sizes, duration of exposure and contributions of specific vegetation or ecosystem types.

Keywords: BVOCs; NK cells; forest bathing; green-blue space; human health; immune system; inflammation; inhalation; natural environments; terpenes.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Flowchart of study selection process (following PRISMA guidelines).
Figure 2
Figure 2
Overview of outcomes from human studies.
Figure 3
Figure 3
Overview of outcomes from animal studies.
See this image and copyright information in PMC

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