The associations between multiple indicators of campus green space exposure and college students' mental health before, during, and after the COVID-19 pandemic.

Campus green space (CGS) is the primary natural environment that college students are exposed to. The health benefits from CGS exposure have received widespread attention. However, few studies have compared the mental health benefits brought by different measures of CGS exposure, or investigated temporal disparities in these associations. This study assessed CGS exposure (March 2022-April 2023) through behavioral trajectories, activity logs, and questionnaires, using the Kessler Psychological Distress Scale (K6) to quantify mental health. We analyzed 264 pre-pandemic, 119 during-pandemic, and 82 post-pandemic participants from Shanghai Jiao Tong University. Our results demonstrated that the indicator of CGS exposure based on activity logs during the pandemic was significantly associated with better mental health (β = -0.300,  = 0.007), with a stronger association than family harmony (β = 0.181) and residential satisfaction(β = -0.177). Indoor plant quantity was also positively correlated with pandemic-era mental health (β = -0.223,  = 0.031). Notably, 17 participants provided longitudinal data across all phases. Based on the results, we have proposed an optimization planning scheme and recommendations for campus greening to improve college students' mental health. This study delivers strategic insights for the health-centric planning and design of campus.