Evidence map›Paper›PMID 40147520›Full record

Trial reportEnvironmental research2025

Forest terpenes and stress: Examining the associations of filtered vs. non-filtered air in a real-life natural environment.

Chaja M Levy, Anne M Riederer, Christopher D Simpson, Amanda J Gassett, Abigail J Gilbert, Michael H Paulsen, Lalith K Silva, Deepak Bhandari, Cody A Newman, Benjamin C Blount and 2 more

Abstract readRandomized Controlled Trial
PubMed Full text at PMC Publisher
In one paragraph

Trial report in Environmental research, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.

0numbers the graph read from it
0cells of the map it votes in
1citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

1 citing paper in PubMed.

  1. Review
4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

12 authors.

Chaja M LevySchool of Environmental and Forest Sciences, University of Washington, USA.
Anne M RiedererDepartment of Environmental and Occupational Health Sciences, University of Washington, USA.
Christopher D SimpsonDepartment of Environmental and Occupational Health Sciences, University of Washington, USA.
Amanda J GassettDepartment of Environmental and Occupational Health Sciences, University of Washington, USA.
Abigail J GilbertDepartment of Environmental and Occupational Health Sciences, University of Washington, USA.
Michael H PaulsenDepartment of Environmental and Occupational Health Sciences, University of Washington, USA.
Lalith K SilvaDivision of Laboratory Sciences, National Center for Environmental Health, U.S. Centers for Disease Control and Prevention, USA.
Deepak BhandariDivision of Laboratory Sciences, National Center for Environmental Health, U.S. Centers for Disease Control and Prevention, USA.
Cody A NewmanDivision of Laboratory Sciences, National Center for Environmental Health, U.S. Centers for Disease Control and Prevention, USA.
Benjamin C BlountDivision of Laboratory Sciences, National Center for Environmental Health, U.S. Centers for Disease Control and Prevention, USA.
Peter H KahnSchool of Environmental and Forest Sciences, University of Washington, USA; Department of Psychology, University of Washington, USA.
Gregory N BratmanSchool of Environmental and Forest Sciences, University of Washington, USA; Department of Environmental and Occupational Health Sciences, University of Washington, USA; Department of Psychology, University of Washington, USA. Electronic address: bratman@uw.edu.

Funding

XENOBIOTIC BIOTRANSFORMATION AND DISPOSITIONP30ES007033 · NIEHS · UNIVERSITY OF WASHINGTON · PI Nicole Ann Errett · 1995 to 2026
$42.5M
Methods and Data CoreR24HD042828 · NICHD · UNIVERSITY OF WASHINGTON · PI ELLIS, JOHN MARK · 2002 to 2016
$9.3M
Scientific/Technical CoreP2CHD042828 · NICHD · UNIVERSITY OF WASHINGTON · PI SARA R. CURRAN · 2017 to 2026
$6.3M
Do terpenes play a role in the stress-reducing effects of a forest bathing intervention?R21AT011242 · NCCIH · UNIVERSITY OF WASHINGTON · PI BRATMAN, GREGORY · 2021 to 2022
$412k
NCCIH NIH HHS R21 AT011242NICHD NIH HHS P2C HD042828NICHD NIH HHS R24 HD042828NIEHS NIH HHS P30 ES007033
6 · The paper itself

Abstract

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.

Indexed as

Air PollutantsForestsStress, PhysiologicalStress, PsychologicalTerpenesAdultAir FiltersBlood PressureCross-Over StudiesDouble-Blind MethodFemaleHeart RateHumansMaleMiddle AgedYoung AdultAir PollutantsTerpenesForestHealthNatureStressTerpenes

Identifiers

PMID40147520
PMCPMC12103269

What Socratic holds

Textmetadata
LicenceCC BY
Read underepoch 390

Registered trials

None linked

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the Socratic graph.