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Community Forests and Public Health: A Research Agenda
The natural environment is integral to supporting healthy and resilient communities. Community forests (CFs) are forested parcels, typically in rural areas, where community members have access, share governance, and receive various benefits. While considerable research demonstrates that urban parks and forests are important for human health, similar assessments are less available for CFs specifically. Although CFs exist in multiple countries, their policy, ecological, ownership, and governance contexts differ significantly. This review focuses on CFs in the United States. The goals of this project were to systematically review current evidence on the relationship between CFs and human health, identify knowledge gaps in the existing research, and propose a scientific research agenda that identifies critical questions related to CFs and public health in the U.S., with application in other contexts. We conducted a systematic review of the literature, screening 351 studies and assessing twenty-four full-text articles, only one of which met inclusion criteria. This mixed-methods study characterized 70 CFs in the Eastern U.S. and featured four case studies. The majority of CFs (93%) and all case studies identified recreational use as their most common purpose. The evidence base on the health implications of CFs is very thin. Targeted research on CFs and their impact on health could provide evidence to inform CF processes and help optimize their health outcomes. We propose a research agenda on CFs in the U.S. based on several pathways of public health promotion: nature contact, climate mitigation/adaptation, economic opportunities, community cohesion, and equity.
Read moreForest Terpenes and Stress: Examining the Associations of Filtered vs. Non-filtered Air in a Real-Life Natural Environment
Human health may benefit from exposure to a class of biogenic volatile organic compounds (BVOCs) consisting of isoprene units, known as terpenes. In this double-blind, randomized crossover trial, participants sat in a forest for two 60-min sessions, one in which terpenes were filtered out of the ambient air they breathed, and another in which they were not, separated by a minimum of an eight-day washout period. The primary outcome was the high frequency (HF) component of heart rate variability (HRV; measured continuously). Secondary outcomes included skin conductance levels (SCL) (measured continuously), self-reported stress and affect (measured every 20 min), blood pressure, heart rate, cortisol and inflammatory cytokines (measured before and after sessions). Serum concentrations of terpenes (measured before and after sessions) were also assessed to investigate the association of absorbed dose with these outcomes. We did not observe a significant association of filter condition with most outcomes; although the trends for affect, systolic blood pressure, cortisol, TNF-α, and CRP were all in the hypothesized direction. We did observe a significant association with interleukin-6, which was −0.19 pg/mL lower in the terpenes-on vs. terpenes-off condition, adjusted for baseline (95 % CI: −0.35, −0.03); and SCL over the session as a whole. A sensitivity analysis of the subset of data from participants who completed both conditions supports these findings and revealed additional significant associations with SCL (95 % CI: −1.87, −0.05); and TNF-α (95 % CI: −2.63, −0.10). To our knowledge, this is the first RCT to filter terpenes from ambient air during forest contact. Highlights Powered Air Purifying Respirator (PAPR) helmets filtered terpenes from forest air. Psychophysiological and immunological correlates of stress were assessed. IL-6 serum levels lower after sessions with terpenes-on vs. terpenes-off filter. Skin conductance levels (SCL) lower across time with terpenes-on vs. terpenes-off. All other outcomes not significant, but many trended in the hypothesized directions. Keywords Terpenes; Forest; Nature; Health; Stress
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