Tranquillity as a Determinant of Health: A Synthesis of Exposure Surrogates and Operationalization for Environmental...

Tranquillity has historically been regarded as a subjective experience of peace and harmony with nature, yet it is increasingly recognized as a measurable environmental characteristic with potential implications for population health and urban planning. This review synthesizes common tranquillity concepts, their environmental surrogates, and links to health outcomes.

This narrative, conceptual review synthesizes literature identified via iterative PubMed searches (up to May 2025) focused on two domains: environmental exposure surrogates used in epidemiological studies (e.g., green space, natural sound), and indices and modeling approaches developed to spatially map tranquillity. Literature selection was based on conceptual relevance rather than exhaustive coverage.

Tranquillity is a complex construct characterized by the presence of natural elements and low noise exposure. Evidence consistently links green space to reduced stress, improved mental wellbeing, and lower cardiovascular risk, while natural sounds such as birdsong and flowing water have been shown to promote psychological restoration and mitigate noise-related annoyance. The health relevance of tranquillity, however, is not only shaped by individual environmental inputs but also by their interactions: studies suggest that congruent visual and auditory natural elements elicit stronger restorative effects than either input alone.

Despite these insights, existing surrogates and health impact assessments often focus on single exposures, overlooking multisensory dynamics, qualitative aspects such as biodiversity and accessibility, and population-level disparities. Advancing this field requires more integrated and context-sensitive approaches, including longitudinal and multisensory studies, to better quantify the health-promoting potential of tranquillity and inform equitable urban design and policy.