Quantifying nature exposure for the dose-response of green space and mental health: a scoping review

The growing awareness of urban green spaces’ role in promoting mental health necessitates a comprehensive understanding of the dose-response relationship between exposure to green spaces and mental health outcomes. To date, numerous reviews have explored this connection, often focusing on particular health outcomes, while the quantification of nature exposure variables is not assessed in detail. This systematic scoping review aims to fill this knowledge gap by implementing a search strategy focused on the exposure or dose side of the relationship. 140 studies were identified from two major databases following the PRISMA guideline. The specific indicators and methodological approaches for quantifying nature exposure were systematically extracted. Exposure variables were categorized into three dimensions: individual exposure (green space usage behavior, e.g., frequency or duration), objective green space-level exposure (physical characteristics of green spaces, e.g., vegetation cover, facilities), and subjective green space-level exposure (quality characteristics of green spaces through perception, evaluation and attitudes of users). The review highlights that many studies are restricted to basic exposure variables, including frequency and duration of use. Quality characteristics of green spaces as well as individual perception and attitudes are increasingly being applied in addition. Various indicators are used to quantify such quality characteristics, including subjective rating scales and objective evaluation tools. Our results emphasize the importance of considering both individual and contextual factors of nature exposure to allow more precise assessments of dose-response effects. Particularly small-scale differences in green space design only become evident when such details are considered. These insights are fundamental to develop guidelines for urban green spaces to promote mental health and to encourage specific patterns of use.

Key messages

• Urban green space research should go beyond simple exposure metrics like frequency and duration, integrating quality, perception, and preferences to better understand mental health impacts.

• Considering both individual behavior and detailed environmental characteristics enables more precise dose-response insights, supporting targeted urban planning for mental well-being.